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Sample records for sintered permanent magnets

  1. Ce-didymium-Fe-B sintered permanent magnets

    International Nuclear Information System (INIS)

    Homma, M.; Okada, M.; Sugimoto, S.

    1985-01-01

    Present works report the development of the low cost R-Fe-B permanent magnets. The best magnetic properties obtained in this studies are Br=13.5 kG, iHc=10.2 kOe and (BH)max=40 MGOe with an Fe-33.5wt%(5Ce-Didymium)-1wt% B alloy. Topics considered in this paper include cerium alloys, boron alloys, fabrication, capitalized cost, iron alloys, permanent magnets, and magnetic properties

  2. Effects of sintering temperature on the mechanical properties of sintered NdFeB permanent magnets prepared by spark plasma sintering

    International Nuclear Information System (INIS)

    Wang, G.P.; Liu, W.Q.; Huang, Y.L.; Ma, S.C.; Zhong, Z.C.

    2014-01-01

    Sintered NdFeB-based permanent magnets were fabricated by spark plasma sintering (SPS) and a conventional method to investigate the mechanical and magnetic properties. The experimental results showed that sintered NdFeB magnet prepared by the spark plasma sintering (SPS NdFeB) possesses a better mechanical properties compared to the conventionally sintered one, of which the maximum value of bending strength and Vickers hardness was 402.3 MPa and 778.1 MPa, respectively. The effects of sintering temperature on bending strength and Vickers hardness were investigated. It was shown that the bending strength firstly increases to the maximum value and then decreases with the increase of sintering temperature in a certain range. The investigations of microstructures and mechanical properties indicated that the unique sintering mechanism in the SPS process is responsible for the improvement of mechanical properties of SPS NdFeB. Furthermore, the relations between the mechanical properties and relevant microstructure have been analyzed based on the experimental fact. - Highlights: • Studied the sintering temperature effect on strengthening mechanism of NdFeB magnet firstly. • It showed that sintering temperature may effectively affect the mechanical properties. • The maximum bending strength and Vickers hardness was 402.3 MPa and 778.1 MPa, respectively

  3. Effects of sintering temperature on the mechanical properties of sintered NdFeB permanent magnets prepared by spark plasma sintering

    Energy Technology Data Exchange (ETDEWEB)

    Wang, G.P., E-mail: wgp@jxnu.edu.cn [College of Physics and Communication Electronics, Jiangxi Normal University, Nanchang 330022 (China); Liu, W.Q. [Key Laboratory of Advanced Functional Materials Science and Engineering, Ministry of Education, Beijing University of Technology, Beijing 100022 (China); Huang, Y.L.; Ma, S.C.; Zhong, Z.C. [School of Materials Science and Engineering, Nanchang Hangkong University, Nanchang 330063 (China)

    2014-01-15

    Sintered NdFeB-based permanent magnets were fabricated by spark plasma sintering (SPS) and a conventional method to investigate the mechanical and magnetic properties. The experimental results showed that sintered NdFeB magnet prepared by the spark plasma sintering (SPS NdFeB) possesses a better mechanical properties compared to the conventionally sintered one, of which the maximum value of bending strength and Vickers hardness was 402.3 MPa and 778.1 MPa, respectively. The effects of sintering temperature on bending strength and Vickers hardness were investigated. It was shown that the bending strength firstly increases to the maximum value and then decreases with the increase of sintering temperature in a certain range. The investigations of microstructures and mechanical properties indicated that the unique sintering mechanism in the SPS process is responsible for the improvement of mechanical properties of SPS NdFeB. Furthermore, the relations between the mechanical properties and relevant microstructure have been analyzed based on the experimental fact. - Highlights: • Studied the sintering temperature effect on strengthening mechanism of NdFeB magnet firstly. • It showed that sintering temperature may effectively affect the mechanical properties. • The maximum bending strength and Vickers hardness was 402.3 MPa and 778.1 MPa, respectively.

  4. The Effect of Nano-TiC Addition on Sintered Nd-Fe-B Permanent Magnets

    DEFF Research Database (Denmark)

    Mural, Zorjana; Kollo, Lauri; Xia, Manlong

    2017-01-01

    This paper addresses the effect of nano-TiC addition on sintered Nd-Fe-B permanent magnets. TiC nanoparticles were added to sintered Nd-Fe-B magnets with a specific aim to improve the Curie temperature and thermal stability. A standard powder metallurgy route was adopted to prepare the magnets....... It was found that introducing nano-TiC prior to jet milling was effective as the nanoparticles dispersed in the final alloy, concentcalcrating in the neodymium-rich phase of the magnets. Magnets with optimal properties were obtained with the addition of 1 wt% TiC nanoparticles. The hysteresis loop...

  5. Coercivity degradation caused by inhomogeneous grain boundaries in sintered Nd-Fe-B permanent magnets

    Science.gov (United States)

    Chen, Hansheng; Yun, Fan; Qu, Jiangtao; Li, Yingfei; Cheng, Zhenxiang; Fang, Ruhao; Ye, Zhixiao; Ringer, Simon P.; Zheng, Rongkun

    2018-05-01

    Quantitative correlation between intrinsic coercivity and grain boundaries in three dimensions is critical to further improve the performance of sintered Nd-Fe-B permanent magnets. Here, we quantitatively reveal the local composition variation across and especially along grain boundaries using the powerful atomic-scale analysis technique known as atom probe tomography. We also estimate the saturation magnetization, magnetocrystalline anisotropy constant, and exchange stiffness of the grain boundaries on the basis of the experimentally determined structure and composition. Finally, using micromagnetic simulations, we quantify the intrinsic coercivity degradation caused by inhomogeneous grain boundaries. This approach can be applied to other magnetic materials for the analysis and optimization of magnetic properties.

  6. The effect of nano-TiC addition on sintered Nd-Fe-B permanent magnets

    International Nuclear Information System (INIS)

    Mural, Zorjana; Kollo, Lauri; Xia, Manlong; Bahl, Christian R.H.; Abrahamsen, Asger Bech; Bez, Henrique Neves; Link, Joosep; Veinthal, Renno

    2017-01-01

    This paper addresses the effect of nano-TiC addition on sintered Nd-Fe-B permanent magnets. TiC nanoparticles were added to sintered Nd-Fe-B magnets with a specific aim to improve the Curie temperature and thermal stability. A standard powder metallurgy route was adopted to prepare the magnets. It was found that introducing nano-TiC prior to jet milling was effective as the nanoparticles dispersed in the final alloy, concentcalcrating in the neodymium-rich phase of the magnets. Magnets with optimal properties were obtained with the addition of 1 wt% TiC nanoparticles. The hysteresis loop for such magnets showed an improved shape and VSM analysis a coercivity value of 1188 kA/m, a remanence value of 0.96 T and a maximum energy product of 132 kJ/m 3 . The maximum working point and the Curie temperature of the developed magnets were 373 K and 623 K respectively. - Highlights: • Improvement of thermal stability of Nd-Fe-B magnets by introducing nano-TiC prior sintering is proposed. • The mechanism relies on nano-TiC particles behaving as grain growth inhibitors between thin RE-rich phase regions. • The concentration of up to 1 wt% of nano-TiC appears to increase coercivity without a significant decrease in remanence. • The maximum working point and the Curie temperature of the developed magnets are 373 K and 623 K respectively.

  7. The effect of nano-TiC addition on sintered Nd-Fe-B permanent magnets

    Energy Technology Data Exchange (ETDEWEB)

    Mural, Zorjana, E-mail: zorjana.mural@ttu.ee [Department of Materials Engineering, Tallinn University of Technology, Ehitajate tee 5, 19086 Tallinn (Estonia); Kollo, Lauri [Department of Materials Engineering, Tallinn University of Technology, Ehitajate tee 5, 19086 Tallinn (Estonia); Xia, Manlong; Bahl, Christian R.H. [Department of Energy Conversion and Storage, Technical University of Denmark, Frederiksborgvej 399, 4000 Roskilde (Denmark); Abrahamsen, Asger Bech [Department of Wind Energy, Technical University of Denmark, Frederiksborgvej 399, 4000 Roskilde (Denmark); Bez, Henrique Neves [Department of Energy Conversion and Storage, Technical University of Denmark, Frederiksborgvej 399, 4000 Roskilde (Denmark); Link, Joosep [National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, 12618 Tallinn (Estonia); Veinthal, Renno [Department of Materials Engineering, Tallinn University of Technology, Ehitajate tee 5, 19086 Tallinn (Estonia)

    2017-05-01

    This paper addresses the effect of nano-TiC addition on sintered Nd-Fe-B permanent magnets. TiC nanoparticles were added to sintered Nd-Fe-B magnets with a specific aim to improve the Curie temperature and thermal stability. A standard powder metallurgy route was adopted to prepare the magnets. It was found that introducing nano-TiC prior to jet milling was effective as the nanoparticles dispersed in the final alloy, concentcalcrating in the neodymium-rich phase of the magnets. Magnets with optimal properties were obtained with the addition of 1 wt% TiC nanoparticles. The hysteresis loop for such magnets showed an improved shape and VSM analysis a coercivity value of 1188 kA/m, a remanence value of 0.96 T and a maximum energy product of 132 kJ/m{sup 3}. The maximum working point and the Curie temperature of the developed magnets were 373 K and 623 K respectively. - Highlights: • Improvement of thermal stability of Nd-Fe-B magnets by introducing nano-TiC prior sintering is proposed. • The mechanism relies on nano-TiC particles behaving as grain growth inhibitors between thin RE-rich phase regions. • The concentration of up to 1 wt% of nano-TiC appears to increase coercivity without a significant decrease in remanence. • The maximum working point and the Curie temperature of the developed magnets are 373 K and 623 K respectively.

  8. Coercivity enhancement in Nd-Fe-B sintered permanent magnet by Dy nanoparticles doping

    Energy Technology Data Exchange (ETDEWEB)

    Liu, W.Q., E-mail: liuweiqiang77@hotmail.co [College of Materials Science and Engineering, Beijing University of Technology, Beijing 100124 (China); Sun, H. [College of Materials Science and Engineering, Beijing University of Technology, Beijing 100124 (China); Yi, X.F. [Anhui Earth-panda Advance Magnetic Material Co., Ltd., Anhui 231500 (China); Liu, X.C.; Zhang, D.T. [College of Materials Science and Engineering, Beijing University of Technology, Beijing 100124 (China); Yue, M., E-mail: yueming@bjut.edu.c [College of Materials Science and Engineering, Beijing University of Technology, Beijing 100124 (China); Zhang, J.X. [College of Materials Science and Engineering, Beijing University of Technology, Beijing 100124 (China)

    2010-07-02

    Nd-Fe-B permanent magnets with a small amount of Dysprosium (Dy) nanoparticles doping were prepared by conventional sintered method, and the microstructure and magnetic properties of the magnets were studied. Investigation shows that the coercivity rises gradually, while the remanence decreases simultaneously with increased Dy doping amount. As a result, the magnet with 1.5 wt.% Dy exhibits optimal magnetic properties. Further investigation presumed that Dy is enriched as (Nd, Dy){sub 2}Fe{sub 14}B phase in the surface region of the Nd{sub 2}Fe{sub 14}B matrix grains indicated by the enhancement of the magneto-crystalline anisotropy field of the Nd{sub 2}Fe{sub 14}B phase. As a result, the magnet doped with a small amount of Dy nanoparticles possesses remarkably enhanced coercivity without sacrificing its magnetization noticeably.

  9. Compression Molding and Novel Sintering Treatments for Alnico Type-8 Permanent Magnets in Near-Final Shape with Preferred Orientation

    Science.gov (United States)

    Kassen, Aaron G.; White, Emma M. H.; Tang, Wei; Hu, Liangfa; Palasyuk, Andriy; Zhou, Lin; Anderson, Iver E.

    2017-09-01

    Economic uncertainty in the rare earth (RE) permanent magnet marketplace, as well as in an expanding electric drive vehicle market that favors permanent magnet alternating current synchronous drive motors, motivated renewed research in RE-free permanent magnets like "alnico," an Al-Ni-Co-Fe alloy. Thus, high-pressure, gas-atomized isotropic type-8H pre-alloyed alnico powder was compression molded with a clean burn- out binder to near-final shape and sintered to density >99% of cast alnico 8 (full density of 7.3 g/cm3). To produce aligned sintered alnico magnets for improved energy product and magnetic remanence, uniaxial stress was attempted to promote controlled grain growth, avoiding directional solidification that provides alignment in alnico 9. Successful development of solid-state powder processing may enable anisotropically aligned alnico magnets with enhanced energy density to be mass-produced.

  10. On the role of the grain size in the magnetic behavior of sintered permanent magnets

    Science.gov (United States)

    Efthimiadis, K. G.; Ntallis, N.

    2018-02-01

    In this work the finite elements method is used to simulate, by micromagnetic modeling, the magnetic behavior of sintered anisotropic magnets. Hysteresis loops were simulated for different grain sizes in an oriented multigrain sample. By keeping out other parameters that contribute to the magnetic microstructure, such as the sample size, the grain morphology and the grain boundaries mismatch, it has been found that the grain size affects the magnetic properties only if the grains are exchange-decoupled. In this case, as the grain size decreases, a decrease in the nucleation field of a reverse magnetic domain is observed and an increase in the coercive field due to the pinning of the magnetic domain walls at the grain boundaries.

  11. The effect of surface grain reversal on the AC losses of sintered Nd–Fe–B permanent magnets

    Energy Technology Data Exchange (ETDEWEB)

    Moore, Martina, E-mail: m.moore@ifw-dresden.de [Leibniz Institute for Solid State and Materials Research (IFW) Dresden, 01171 Dresden (Germany); Roth, Stefan; Gebert, Annett [Leibniz Institute for Solid State and Materials Research (IFW) Dresden, 01171 Dresden (Germany); Schultz, Ludwig [Leibniz Institute for Solid State and Materials Research (IFW) Dresden, 01171 Dresden (Germany); TU Dresden, Institute for Materials Science, 01062 Dresden (Germany); Gutfleisch, Oliver [TU Darmstadt, Department of Materials Science, Alarich-Weiß-Str. 16, 64287 Darmstadt (Germany); Fraunhofer Project Group for Materials Recycling and Resource Strategies IWKS, 63457 Hanau (Germany)

    2015-02-01

    Sintered Nd–Fe–B magnets are exposed to AC magnetic fields in many applications, e.g. in permanent magnet electric motors. We have measured the AC losses of sintered Nd–Fe–B magnets in a closed circuit arrangement using AC fields with root mean square-values up to 80 mT (peak amplitude 113 mT) over the frequency range 50 to 1000 Hz. Two magnet grades with different dysprosium content were investigated. Around the remanence point the low grade material (1.7 wt% Dy) showed significant hysteresis losses; whereas the losses in the high grade material (8.9 wt% Dy) were dominated by classical eddy currents. Kerr microscopy images revealed that the hysteresis losses measured for the low grade magnet can be mainly ascribed to grains at the sample surface with multiple domains. This was further confirmed when the high grade material was subsequently exposed to DC and AC magnetic fields. Here a larger number of surface grains with multiple domains are also present once the step in the demagnetization curve attributed to the surface grain reversal is reached and a rise in the measured hysteresis losses is evident. If in the low grade material the operating point is slightly offset from the remanence point, such that zero field is not bypassed, its AC losses can also be fairly well described with classical eddy current theory. - Highlights: • The eddy current losses of sintered Nd–Fe–B magnets were measured. • Field amplitudes up to 113 mT over the frequency range 50 to 1000 Hz were applied. • The Nd–Fe–B magnets showed significant hysteresis losses at low amplitudes (∼100 mT). • The source of such hysteresis losses in sintered Nd–Fe–B magnets was identified. • Two magnet grades with different dysprosium content were investigated.

  12. The effect of surface grain reversal on the AC losses of sintered Nd–Fe–B permanent magnets

    International Nuclear Information System (INIS)

    Moore, Martina; Roth, Stefan; Gebert, Annett; Schultz, Ludwig; Gutfleisch, Oliver

    2015-01-01

    Sintered Nd–Fe–B magnets are exposed to AC magnetic fields in many applications, e.g. in permanent magnet electric motors. We have measured the AC losses of sintered Nd–Fe–B magnets in a closed circuit arrangement using AC fields with root mean square-values up to 80 mT (peak amplitude 113 mT) over the frequency range 50 to 1000 Hz. Two magnet grades with different dysprosium content were investigated. Around the remanence point the low grade material (1.7 wt% Dy) showed significant hysteresis losses; whereas the losses in the high grade material (8.9 wt% Dy) were dominated by classical eddy currents. Kerr microscopy images revealed that the hysteresis losses measured for the low grade magnet can be mainly ascribed to grains at the sample surface with multiple domains. This was further confirmed when the high grade material was subsequently exposed to DC and AC magnetic fields. Here a larger number of surface grains with multiple domains are also present once the step in the demagnetization curve attributed to the surface grain reversal is reached and a rise in the measured hysteresis losses is evident. If in the low grade material the operating point is slightly offset from the remanence point, such that zero field is not bypassed, its AC losses can also be fairly well described with classical eddy current theory. - Highlights: • The eddy current losses of sintered Nd–Fe–B magnets were measured. • Field amplitudes up to 113 mT over the frequency range 50 to 1000 Hz were applied. • The Nd–Fe–B magnets showed significant hysteresis losses at low amplitudes (∼100 mT). • The source of such hysteresis losses in sintered Nd–Fe–B magnets was identified. • Two magnet grades with different dysprosium content were investigated

  13. Multi-layered electroless Ni-P coatings on powder-sintered Nd-Fe-B permanent magnet

    International Nuclear Information System (INIS)

    Chen Zhong; Ng, Alice; Yi Jianzhang; Chen Xingfu

    2006-01-01

    This paper has shown a successful protective coating scheme for powder-sintered Nd-Fe-B permanent magnet using multi-layered electroless nickel (EN) deposition. A low-phosphorus nickel layer is plated with an alkaline EN solution first, followed by a high-phosphorus nickel layer plated with an acidic solution. An additional topcoat by medium-phosphorus nickel on the high-phosphorus coating is also explored. It is shown that the high-phosphorus nickel layer coated in acidic solution provides the best corrosion protection because of its dense amorphous structure. The medium phosphorus topcoat is also dense and is able to provide reasonable corrosion resistance. The low-phosphorus layer itself does not have enough corrosion resistance; its main role is to provide an intermediate coating on the powder-sintered magnet. X-ray diffraction measurement shows that the low-phosphorus coating consists of nano-crystallines, and the high- and the medium-phosphorus coatings are dominated by amorphous structure. Microscopic observation and scratch test on these composite coatings demonstrate good adhesion between the magnet and the coatings. Remanence and coercivity of the plated magnet decrease with the applied coatings, but measured values are still very attractive for practical applications among known hard magnets

  14. Grain boundary engineering in sintered Nd-Fe-B permanent magnets for efficient utilization of heavy rare earth elements

    Energy Technology Data Exchange (ETDEWEB)

    Loewe, Konrad

    2016-10-18

    The first part of the thesis investigates the diffusion of rare-earth (RE) elements in commercial sintered Nd-Fe-B based permanent magnets. A strong temperature dependence of the diffusion distance and resulting change in magnetic properties were found. A maximum increase in coercivity of ∼+350 kA/m using a Dy diffusion source occurred at the optimum annealing temperature of 900 C. After annealing for 6 h at this temperature, a Dy diffusion distance of about 4 mm has been observed with a scanning Hall probe. Consequently, the maximum thickness of grain boundary diffusion processed magnets with homogeneous properties is also only a few mm. The microstructural changes in the magnets after diffusion were investigated by electron microscopy coupled with electron probe microanalysis. It was found that the diffusion of Dy into sintered Nd-Fe-B permanent magnets occurs along the grain boundary phases, which is in accordance with previous studies. A partial melting of the Nd-Fe-B grains during the annealing process lead to the formation of so - called (Nd,Dy)-Fe-B shells at the outer part of the grains. These shells are μm thick at the immediate surface of the magnet and become thinner with increasing diffusion distance towards the center of the bulk. With scanning transmission electron microscopy coupled with electron probe analysis a Dy content of about 1 at.% was found in a shell located about 1.5 mm away from the surface of the magnet. The evaluation of diffusion speeds of Dy and other RE (Tb, Ce, Gd) in Nd-Fe-B magnets showed that Tb diffuses significantly faster than Dy, and Ce slightly slower than Dy, which is attributed to differences in the respective phase diagrams. The addition of Gd to the grain boundaries has an adverse effect on coercivity. Exemplary of the heavy rare earth element Tb, the nano - scale elemental distribution around the grain boundaries after the diffusion process was visualized with high resolution scanning transmission electron microscopy

  15. Effect of sintering in a hydrogen atmosphere on the density and coercivity of (Sm,Zr)(Co,Cu,Fe)Z permanent magnets

    Science.gov (United States)

    Burkhanov, G. S.; Dormidontov, N. A.; Kolchugina, N. B.; Dormidontov, A. G.

    2018-04-01

    The effect of heat treatments in manufacturing (Sm,Zr)(Co,Cu,Fe)Z-based permanent magnets sintered in a hydrogen atmosphere on their properties has been studied. It was shown that the dynamics of the magnetic hardening of the studied magnets during heat treatments, in whole, corresponds to available concepts of phase transformations in five-component precipitation-hardened SmCo-based alloys. Peculiarities of the studied compositions consist in the fact that the coercive force magnitude of magnets quenched from the isothermal aging temperature is higher by an order of magnitude than those available in the literature. It was noted that, in using the selected manufacturing procedure, the increase in the density of samples does not finish at the sintering stage but continues in the course of solid-solution heat treatment.

  16. Study of the magnetic microstructure of high-coercivity sintered SmCo5 permanent magnets with the conventional Bitter pattern technique and the colloid-SEM method

    International Nuclear Information System (INIS)

    Szmaja, Witold

    2007-01-01

    The magnetic microstructure of high-coercivity sintered SmCo 5 permanent magnets was studied with the conventional Bitter pattern technique, and also for the first time with the colloid-scanning electron microscopy (colloid-SEM) method. Both techniques were supported by digital image acquisition, enhancement and analysis. Thanks to this, it was possible to obtain high-contrast and clear images of the magnetic microstructure and to analyze them in detail, and consequently also to achieve improvements over earlier results. In the thermally demagnetized state the grains were composed of magnetic domains. On the surface perpendicular to the alignment axis, the main domains forming a maze pattern and surface reverse spikes were observed. Investigations on the surface parallel to the alignment axis, especially by the colloid-SEM technique, provided a detailed insight into the orientation of grains. The alignment of grains was good, but certainly not perfect; there were also strongly misaligned grains, although generally very rare. In most cases the domain structures within grains were independent of their neighbors, but in some cases (not so rare) the domain walls were observed to continue through the grain boundaries, indicating significant magnetostatic interaction between neighboring grains. Studies of the behavior of the magnetic microstructure under the influence of an external magnetic field, performed for the first time on the surface parallel to the alignment axis (with the conventional Bitter pattern method), showed that the domain walls move easily within the grains and that the magnetization reversal mechanism is mainly related to the nucleation and growth of reverse domains, i.e. that sintered SmCo 5 magnets are nucleation-dominated systems. Groupwise magnetization reversal of adjacent magnetically coupled grains was observed, an unfavorable effect for high-coercivity magnets. Images obtained by the colloid-SEM technique and the conventional Bitter pattern

  17. Microstructural and electrochemical characterization of Ni/Ti/sub 2/N composite coating for sintered NdFeB permanent magnets

    International Nuclear Information System (INIS)

    Ali, A.; Ahmad, A.; Deen, K.M.; Ahmad, R.

    2009-01-01

    Sintered NdFeB magnets have complex microstructure that makes them susceptible to corrosion in humid or moist environments. The paper presents the anticorrosion characteristics of a novel Ni/Ti/sub 2/N composite coating applied through electrodeposition and cathodic arc physical vapour deposition (CAPVD) to sintered NdFeB permanent magnets. The performance of composite coating was evaluated in simulated marine environment with the help of dc polarization techniques. The rate of coating degradation was also determined by employing ac electrochemical impedance spectroscopy (EIS). The coating morphology and surface chemistry were studied with scanning electron microscope (SEM). X-ray diffraction (XRD) was used for identification of component phases in the coating-substrate system. The results showed that the composite coating provided an adequately improved corrosion protection to the sintered NdFeB magnets in the simulated marine environment compared to the earlier reported ceramic and metallic coatings. The composite coating did not damage the magnetic properties of coating-substrate system that remained at par with the ceramic and nickel coating having copper interlayer. (author)

  18. Effect of Stabilization Heat Treatment on Time-Dependent Polarization Losses in Sintered Nd-Fe-B Permanent Magnets

    Directory of Open Access Journals (Sweden)

    Tuominen S.

    2013-01-01

    Full Text Available Some companies in the motor and generator industry utilizing sintered NdFeB magnets have adopted pre-ageing heat treatment in order to improve the stability of the magnets. The parameters of this stabilization heat treatment are based mainly on assumptions rather than on any published research results. In this work, the effects of pre-ageing treatment on the time-dependent polarization losses of two different types of commercial sintered NdFeB magnets were studied. The material showing the squarer J(H curve did not benefit from the pre-ageing treatment, since it seems to be stable under a certain critical temperature. In contrast, a stabilizing effect was observed in the material showing rounder J(H curve. After the stabilization heat treatment, the polarization of the magnets was found to be at lower level, but unchanged over a certain period of time. The length of this period depends on the temperature and the duration of the pre-ageing treatment. In addition, our analysis reveals that the stabilization heat treatment performed in an open circuit condition does not stabilize the magnet uniformly.

  19. Effect of titania particles on the microstructure and properties of the epoxy resin coatings on sintered NdFeB permanent magnets

    International Nuclear Information System (INIS)

    Xu, J.L.; Huang, Z.X.; Luo, J.M.; Zhong, Z.C.

    2014-01-01

    The nanometer titania particles enhanced epoxy resin composite coatings were prepared on the sintered NdFeB permanent magnets by cathodic electrophoretic deposition. The effects of titania particle concentrations on the microstructure and properties of the epoxy coatings were investigated by surface and cross-sectional morphologies observation, surface roughness and microhardness measurement, H 2 SO 4 solution immersion test, neutral salt spray test and magnetic properties measurement. The results showed that the thickness of epoxy coatings with and without the titania particles addition was about 40 μm. The titania particles could be uniformly dispersed and embedded in the epoxy matrix if the titania particles concentration was lower than 40 g/l. With increasing titania particle concentrations, the number of the particles embedded in the epoxy matrix increased and the surface roughness and microhardness of the composite coatings increased. At the same time, the weight loss of the coated samples immersed in H 2 SO 4 solution decreased and the neutral salt spray time of the coated samples prolonged. It could be concluded that the titania particles did not change the thickness of the epoxy coatings and did not deteriorate the magnetic properties of NdFeB substrates, but could greatly improve the microhardness and corrosion resistance of the epoxy coatings. - Highlights: • The titania particles enhanced epoxy resin coatings were prepared on sintered NdFeB by cathodic electrophoretic deposition. • The titania particles could be uniformly dispersed and embedded in the epoxy resin matrix. • With increasing titania concentrations, the surface roughness and the microhardness of composite coatings increased. • The addition of titania particles greatly improved the corrosion resistance of the epoxy coatings. • The composition coatings did not deteriorate the magnetic properties of NdFeB substrates

  20. Effect of titania particles on the microstructure and properties of the epoxy resin coatings on sintered NdFeB permanent magnets

    Energy Technology Data Exchange (ETDEWEB)

    Xu, J.L., E-mail: jlxu@nchu.edu.cn; Huang, Z.X.; Luo, J.M.; Zhong, Z.C., E-mail: zzhong.2006@yahoo.com.cn

    2014-04-15

    The nanometer titania particles enhanced epoxy resin composite coatings were prepared on the sintered NdFeB permanent magnets by cathodic electrophoretic deposition. The effects of titania particle concentrations on the microstructure and properties of the epoxy coatings were investigated by surface and cross-sectional morphologies observation, surface roughness and microhardness measurement, H{sub 2}SO{sub 4} solution immersion test, neutral salt spray test and magnetic properties measurement. The results showed that the thickness of epoxy coatings with and without the titania particles addition was about 40 μm. The titania particles could be uniformly dispersed and embedded in the epoxy matrix if the titania particles concentration was lower than 40 g/l. With increasing titania particle concentrations, the number of the particles embedded in the epoxy matrix increased and the surface roughness and microhardness of the composite coatings increased. At the same time, the weight loss of the coated samples immersed in H{sub 2}SO{sub 4} solution decreased and the neutral salt spray time of the coated samples prolonged. It could be concluded that the titania particles did not change the thickness of the epoxy coatings and did not deteriorate the magnetic properties of NdFeB substrates, but could greatly improve the microhardness and corrosion resistance of the epoxy coatings. - Highlights: • The titania particles enhanced epoxy resin coatings were prepared on sintered NdFeB by cathodic electrophoretic deposition. • The titania particles could be uniformly dispersed and embedded in the epoxy resin matrix. • With increasing titania concentrations, the surface roughness and the microhardness of composite coatings increased. • The addition of titania particles greatly improved the corrosion resistance of the epoxy coatings. • The composition coatings did not deteriorate the magnetic properties of NdFeB substrates.

  1. Permanent quadrupole magnets

    International Nuclear Information System (INIS)

    Bush, E.D. Jr.

    1976-01-01

    A family of quadrupole magnets using a soft iron return yoke and circular cross-section permanent magnet poles were fabricated to investigate the feasibility for use in ion or electron beam focusing applications in accelerators and transport lines. Magnetic field measurements yielded promising results. In fixed-field applications, permanent magnets with sufficient gradients would be a low cost substitute for conventional electromagnets, eliminating the need for power supplies, associated wiring, and cooling. (author)

  2. Introduction to permanent magnets

    International Nuclear Information System (INIS)

    Zijlstra, H.

    1985-01-01

    Some general considerations concerning the application of permanent magnets are developed. The relevant magnet properties are discussed, with particular reference to Nd-Fe-B alloy. The author comes to the following conclusions; the air gap field B should be high, for high electrical efficiency; the magnet should face the air gap, for efficient use of the magnet material; the magnet material should therefore have a high remanence; and the new Nd-Fe-B magnet fits in nicely, having (potentially) the highest remanence ever reported in permanent magnets, combined with sufficient coercivity to sustain it

  3. Permanent quadrupole magnets

    International Nuclear Information System (INIS)

    Bush, E.D. Jr.

    1976-01-01

    A family of quadrupole magnets using a soft iron return yoke and circular cross-section permanent magnet poles were fabricated to investigate the feasibility for use in ion or electron beam focusing applications in accelerators and transport lines. Magnetic field measurements yielded promising results. In fixed-field applications, permanent magnets with sufficient gradients would be a low cost substitute for conventional electromagnets, eliminating the need for power supplies, associated wiring, and cooling. Based on preliminary tests, it was seen that permanent quadrupole magnets can offer a low cost, reliable solution in applications requiring small, fixed-field focusing devices for use in ion or electron-beam transport systems. Permanent magnets do require special considerations in design, fabrication, handling, and service that are different than encountered in conventional quadrupole magnets. If these basic conditions are satisfied, the resulting beam-focusing device would be stable, maintenance free, with virtually an indefinite lifetime

  4. The coercivity mechanism of sintered SM(Co_b_a_lFe_0_._2_4_5Cu_0_._0_7Zr_0_._0_2)_7_._8 permanent magnets with different isothermal annealing time

    International Nuclear Information System (INIS)

    Sun, Wei; Zhu, Minggang; Guo, Zhaohui; Fang, Yikun; Li, Wei

    2015-01-01

    Precipitation-hardened 2:17-type SmCo permanent magnet has attracted much attention due to its high Curie temperature and excellent magnetic properties. Sm(Co_b_a_lFe_0_._2_4_5Cu_0_._0_7Zr_0_._0_2)_7_._8 (at%) sintered magnets with high remanence (B_r ~1.15 T) were prepared using a traditional powder metallurgy method. The intrinsic coercivity H_c_j of the magnets was increased from 429 to 994 kA m"−"1 with isothermal annealing time increasing from 10 to 40 h, which is different from the phenomenon that increasing aging time leads to a reduced coercivity mentioned in the Ref. [16]. In consideration of rarely report about the microstructure of the final magnet isothermally annealed for 40 h, we have tried to originally analyze the relationship between the microstructure and the magnetic properties. Besides, the lattice constants of sintered Sm(Co_b_a_lFe_0_._2_4_5Cu_0_._0_7Zr_0_._0_2)_7_._8 permanent magnet isothermally annealed for 40 h have been given by indexing the HRTEM results including the selected area electron diffraction (SAED) and HRTEM images.

  5. Progress of sintered NdFeB permanent magnets by the diffusion of non-rare earth elements and their alloy compounds

    Directory of Open Access Journals (Sweden)

    Lyu Meng

    2017-12-01

    Full Text Available It has been found that the coercivity (HC and corrosivity of sintered NdFeB magnets are closely related to the components and microstructure of their intergranular phase.The traditional smelting NdFeB magnets with adding heavy rare earth elements can modify intergranular phase to improve the HC and corrosion resistance of magnets.However,it makes the additives be homogenously distributed on the main phase,and causes magnetic decrease and cost increase.With the addition of non-rare earth materials into grain boundary,the microstructure of intergranular phase as well as its electrochemical potential and wettability can be optimized.As a result,the amount of heavy rare earth elements and cost of magnets could be reduced whilst the HC and corrosion resistance of magnets can be improved.This paper summarized the research on regulating the components and the microstructure of intergranular phase in sintered NdFeB magnets by non-rare earth metals and compounds,and its influence on coercivity and corrosion resistance.

  6. Impulse Magnetization of Nd-Fe-B Sintered Magnets for Sensors

    Directory of Open Access Journals (Sweden)

    Marek Przybylski

    2016-04-01

    Full Text Available Magnetization of large Nd-Fe-B sintered permanent magnets is still challenging. This type of permanent magnet is electrically conductive, so impulse magnetization causes a flow of eddy currents which prevent magnetization of the whole volume of the magnet. The paper deals with the impulse magnetization of sintered Nd-Fe-B permanent magnets and shows a method for the determination of suitable parameters for the supply system. The necessary magnetic field strength for magnetization of the magnet to saturation was determined. The optimal magnetizing fixture supply voltage for magnetization to saturation was determined from simulations in PSpice software, finite element analyses in Maxwell 15 and measurements. Measurements of magnetic induction on the surface of the Nd-Fe-B magnet are also presented to ensure that a magnet with 70 mm diameter and 20 mm in height is fully saturated.

  7. New permanent magnets

    Science.gov (United States)

    Müller, K.-H.; Krabbes, G.; Fink, J.; Gruß, S.; Kirchner, A.; Fuchs, G.; Schultz, L.

    2001-05-01

    Permanent magnets play an important role and are widely spread in daily-life applications. Due to their very low costs, large availability of the row materials and their high chemical stability, hard ferrites are still dominant in the permanent magnet market although their relatively poor magnetic properties are a distinct disadvantage. Today's high-performance magnets are mostly made from Nd 2Fe 14B. The aim of research is to combine the large spontaneous magnetization of 3d metals with strong anisotropy fields known from rare-earth transition-metal compounds and, at the same time, to maintain a high value of the Curie temperature. However, the number of iron-rich rare-earth intermetallics is very limited and, consequently, not much success can be noted in this field for the last 10 years. One alternative concept is to use magnetic fields trapped in type II superconductors where much higher fields can be achieved compared to conventional rare-earth magnets. Very recently, we obtained a trapped field as high as 14.4 T in a melt-textured YBCO bulk sample of a few centimeters in diameter. This is the highest value ever achieved in a bulk superconductor. The trapped field of a superconductor is not governed by the Laplace equation and, therefore, levitation works without any additional (active) stabilization. The disadvantage of these magnets is their low working temperature (of liquid nitrogen and below).

  8. Variable Permanent Magnet Quadrupole

    International Nuclear Information System (INIS)

    Mihara, T.; Iwashita, Y.; Kyoto U.; Kumada, M.; NIRS, Chiba; Spencer, C.M.; SLAC

    2007-01-01

    A permanent magnet quadrupole (PMQ) is one of the candidates for the final focus lens in a linear collider. An over 120 T/m strong variable permanent magnet quadrupole is achieved by the introduction of saturated iron and a 'double ring structure'. A fabricated PMQ achieved 24 T integrated gradient with 20 mm bore diameter, 100 mm magnet diameter and 20 cm pole length. The strength of the PMQ is adjustable in 1.4 T steps, due to its 'double ring structure': the PMQ is split into two nested rings; the outer ring is sliced along the beam line into four parts and is rotated to change the strength. This paper describes the variable PMQ from fabrication to recent adjustments

  9. Hydrogen stability of SmCo5 permanent magnet

    International Nuclear Information System (INIS)

    Lukin, A.; Rabinovich, Y.; Bala, H.

    2001-01-01

    The present work has been performed with purpose to determine the level of hydrogen stability of sintered SmCo 5 permanent magnets by means of accelerated tests, to study the effect of hydrogen on the magnetic and mechanical properties of the permanent magnets and to establish the criteria of hydrogenation level and the activation energy of this process. In addition, the effect of hydrogen on the properties of sintered SmCo 5 permanent magnets in specific conditions of exploitation and storage durability of instruments was studied

  10. Preparation and characterization of amorphous SiO2 coatings deposited by mirco-arc oxidation on sintered NdFeB permanent magnets

    International Nuclear Information System (INIS)

    Xu, J.L.; Xiao, Q.F.; Mei, D.D.; Zhong, Z.C.; Tong, Y.X.; Zheng, Y.F.; Li, L.

    2017-01-01

    Amorphous SiO 2 coatings were prepared on sintered NdFeB magnets by micro-arc oxidation (MAO) in silicate solution. The surface and cross-sectional morphologies, element and phase composition, corrosion resistance and magnetic properties of the coatings were investigated by scanning electron microscopy (SEM), energy dispersive X-ray spectrometer (EDS), X-ray photoelectron spectroscopy (XPS), potentiodynamic polarization test and physical properties measurements system (PPMS). The results showed that the surface morphologies of the coatings exhibited the “coral reef” like structure, different from the typical MAO porous structure. With increasing the voltages, the thickness of the coatings increased from 12.72 to 19.90 µm, the content of Si element increased, while the contents of Fe, Nd and P elements decreased. The coatings were mainly composed of amorphous SiO 2 and a few amorphous Fe 2 O 3 and Nd 2 O 3 . The amorphous SiO 2 coatings presented excellent thermal shock resistance, while the thermal shock resistance decreased with increasing the voltages. The corrosion resistance of the coatings increased with increasing the voltages, and it could be enhanced by one order of magnitude compared to the uncoated NdFeB magnets. The MAO coatings slightly decreased the magnetic properties of the NdFeB samples in different degrees. - Highlights: • Amorphous SiO 2 coatings were prepared on sintered NdFeB magnets by micro-arc oxidation. • The coatings presented excellent thermal shock resistance. • The corrosion resistance could be enhanced by one order of magnitude. • The MAO coatings slightly decreased the magnetic properties of the NdFeB samples.

  11. Preparation and characterization of amorphous SiO{sub 2} coatings deposited by mirco-arc oxidation on sintered NdFeB permanent magnets

    Energy Technology Data Exchange (ETDEWEB)

    Xu, J.L., E-mail: jlxu@nchu.edu.cn [Center for Biomedical Materials and Engineering, Harbin Engineering University, Harbin 150001 (China); School of Materials Science and Engineering, Nanchang Hangkong University, Nanchang 330063 (China); Xiao, Q.F.; Mei, D.D. [School of Materials Science and Engineering, Nanchang Hangkong University, Nanchang 330063 (China); Zhong, Z.C., E-mail: zzhong2014@sina.com [The Institute for Rare Earth Magnetic Materials and Devices, Jiangxi University of Science and Technology, Ganzhou 341000 (China); Tong, Y.X. [Center for Biomedical Materials and Engineering, Harbin Engineering University, Harbin 150001 (China); Zheng, Y.F., E-mail: yfzheng@pku.edu.cn [Center for Biomedical Materials and Engineering, Harbin Engineering University, Harbin 150001 (China); Li, L. [Center for Biomedical Materials and Engineering, Harbin Engineering University, Harbin 150001 (China)

    2017-03-15

    Amorphous SiO{sub 2} coatings were prepared on sintered NdFeB magnets by micro-arc oxidation (MAO) in silicate solution. The surface and cross-sectional morphologies, element and phase composition, corrosion resistance and magnetic properties of the coatings were investigated by scanning electron microscopy (SEM), energy dispersive X-ray spectrometer (EDS), X-ray photoelectron spectroscopy (XPS), potentiodynamic polarization test and physical properties measurements system (PPMS). The results showed that the surface morphologies of the coatings exhibited the “coral reef” like structure, different from the typical MAO porous structure. With increasing the voltages, the thickness of the coatings increased from 12.72 to 19.90 µm, the content of Si element increased, while the contents of Fe, Nd and P elements decreased. The coatings were mainly composed of amorphous SiO{sub 2} and a few amorphous Fe{sub 2}O{sub 3} and Nd{sub 2}O{sub 3}. The amorphous SiO{sub 2} coatings presented excellent thermal shock resistance, while the thermal shock resistance decreased with increasing the voltages. The corrosion resistance of the coatings increased with increasing the voltages, and it could be enhanced by one order of magnitude compared to the uncoated NdFeB magnets. The MAO coatings slightly decreased the magnetic properties of the NdFeB samples in different degrees. - Highlights: • Amorphous SiO{sub 2} coatings were prepared on sintered NdFeB magnets by micro-arc oxidation. • The coatings presented excellent thermal shock resistance. • The corrosion resistance could be enhanced by one order of magnitude. • The MAO coatings slightly decreased the magnetic properties of the NdFeB samples.

  12. Cryogenic Permanent Magnet Undulators

    International Nuclear Information System (INIS)

    Chavanne, J.; Lebec, G.; Penel, C.; Revol, F.; Kitegi, C.

    2010-01-01

    For an in-vacuum undulator operated at small gaps the permanent magnet material needs to be highly resistant to possible electron beam exposure. At room temperature, one generally uses Sm 2 Co 17 or high coercivity NdFeB magnets at the expense of a limited field performance. In a cryogenic permanent magnet undulator (CPMU), at a temperature of around 150 K, any NdFeB grade reveals a coercivity large enough to be radiation resistant. In particular, very high remanence NdFeB material can be used to build undulators with enhanced field and X-ray brilliance at high photon energy provided that the pre-baking of the undulator above 100 deg. C can be eliminated. The ESRF has developed a full scale 2 m long CPMU with a period of 18 mm. This prototype has been in operation on the ID6 test beamline since January 2008. A significant effort was put into the characterization of NdFeB material at low temperature, the development of dedicated magnetic measurement systems and cooling methods. The measured heat budget with beam is found to be larger than expected without compromising the smooth operation of the device. Leading on from this first experience, new CPMUs are currently being considered for the upgrade of the ESRF.

  13. Superconducting permanent magnets

    International Nuclear Information System (INIS)

    Wipf, S.L.; Laquer, H.L.

    1989-01-01

    The concept of superconducting permanent magnets with fields trapped in shells or cylinders of Type II superconductors is an old one. Unfortunately, the low values of 0.5 to 1T for the first flux jump field, which is independent of the actual current density, have frustrated its implementation with classical Type II superconductors. The fact that the flux jump fields for high temperature superconductors should be an order of magnitude larger at liquid nitrogen temperatures allows us to reconsider these options. Analysis of the hysteresis patterns, based on the critical state model, shows that, if the dimensions are chosen so that the sample is penetrated at a field B/sub p/, which is equal to or just less than the first flux jump field, B/sub fj/, a temporarily applied field of 2B/sub fj/ will trap 0.5 B/sub fj/. Thus for a 90 K superconductor with a B/sub fj/ of 6T, a permanent field of 3 T should be trapped, with an energy product of 1.8 MJ/m/sup 3/ (225 MG . Oe). This is five times as large as for the best permanent magnet materials. The authors discuss means to verify the analysis and the limitations imposed by the low critical current densities in presently available high temperature superconductors

  14. Preparation and characterization of amorphous SiO2 coatings deposited by mirco-arc oxidation on sintered NdFeB permanent magnets

    Science.gov (United States)

    Xu, J. L.; Xiao, Q. F.; Mei, D. D.; Zhong, Z. C.; Tong, Y. X.; Zheng, Y. F.; Li, L.

    2017-03-01

    Amorphous SiO2 coatings were prepared on sintered NdFeB magnets by micro-arc oxidation (MAO) in silicate solution. The surface and cross-sectional morphologies, element and phase composition, corrosion resistance and magnetic properties of the coatings were investigated by scanning electron microscopy (SEM), energy dispersive X-ray spectrometer (EDS), X-ray photoelectron spectroscopy (XPS), potentiodynamic polarization test and physical properties measurements system (PPMS). The results showed that the surface morphologies of the coatings exhibited the "coral reef" like structure, different from the typical MAO porous structure. With increasing the voltages, the thickness of the coatings increased from 12.72 to 19.90 μm, the content of Si element increased, while the contents of Fe, Nd and P elements decreased. The coatings were mainly composed of amorphous SiO2 and a few amorphous Fe2O3 and Nd2O3. The amorphous SiO2 coatings presented excellent thermal shock resistance, while the thermal shock resistance decreased with increasing the voltages. The corrosion resistance of the coatings increased with increasing the voltages, and it could be enhanced by one order of magnitude compared to the uncoated NdFeB magnets. The MAO coatings slightly decreased the magnetic properties of the NdFeB samples in different degrees.

  15. Investigation of Anisotropic Bonded Magnets in Permanent Magnet Machine Applications

    Science.gov (United States)

    Khazdozian, H. A.; McCall, S. K.; Kramer, M. J.; Paranthaman, M. P.; Nlebedim, I. C.

    Rare earth elements (REE) provide the high energy product necessary for permanent magnets, such as sintered Nd2Fe14B, in many applications like wind energy generators. However, REEs are considered critical materials due to risk in their supply. To reduce the use of critical materials in permanent magnet machines, the performance of anisotropic bonded NdFeB magnets, aligned under varying magnetic field strength, was simulated using 3D finite element analysis in a 3MW direct-drive permanent magnet generator (DDPMG), with sintered N42 magnets used as a baseline for comparison. For direct substitution of the anisotropic bonded magnets, approximately 85% of the efficiency of the baseline model was achieved, irrespective of the alignment field. The torque and power generation of the DDPMG was not found to vary significantly with increase in the alignment field. Finally, design changes were studied to allow for the achievement of rated torque and power with the use of anisotropic bonded magnets, demonstrating the potential for reduction of critical materials in permanent magnets for renewable energy applications. This work was supported by the Critical Materials Institute, an Energy Innovation Hub funded by the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Advanced Manufacturing Office.

  16. Rare earth elements and permanent magnets (invited)

    Science.gov (United States)

    Dent, Peter C.

    2012-04-01

    Rare earth (RE) magnets have become virtually indispensible in a wide variety of industries such as aerospace, automotive, electronics, medical, and military. RE elements are essential ingredients in these high performance magnets based on intermetallic compounds RECo5, RE2TM17 (TM: transition metal), and RE2TM14B. Rare earth magnets are known for their superior magnetic properties—high induction, and coercive force. These properties arise due to the extremely high magnetocrystalline anisotropy made possible by unique 3d-4f interactions between transition metals and rare earths. For more than 40 years, these magnets remain the number one choice in applications that require high magnetic fields in extreme operating conditions—high demagnetization forces and high temperature. EEC produces and specializes in RECo5 and RE2TM17 type sintered magnets. Samarium and gadolinium are key RE ingredients in the powder metallurgical magnet production processes which include melting, crushing, jet milling, pressing, sintering, and heat treating. The magnetic properties and applications of these magnets will be discussed. We will also briefly discuss the past, current, and future of the permanent magnet business. Currently, over 95% of all pure rare earth oxides are sourced from China, which currently controls the market. We will provide insights regarding current and potential new magnet technologies and designer choices, which may mitigate rare earth supply chain issues now and into the future.

  17. Magnetic spring based on two permanent magnets

    International Nuclear Information System (INIS)

    Tsivilitsin, V.Yu.; Mil'man, Yu.V.; Goncharuk, V.A.; Bondar, I.B.

    2011-01-01

    A new type of the magnetic spring construction 'two permanent magnets' has been considered. A mathematical expression for the estimation of a pulling-in force has been offered. This expression is verified experimentally on the produced operating magnetic spring. The theoretical and experimental data are in good accordance. A number of advantages of the magnetic spring over the construction 'permanent magnet - magnetic circuit' such as an insignificant friction force between two magnets and a higher pulling force are discussed.

  18. Permanent magnets and its production by powder metallurgy

    Directory of Open Access Journals (Sweden)

    Enrique Herraiz Lalana

    2018-06-01

    Full Text Available In this work, the historical relationship between permanent magnets and powder metallurgy is reviewed. Powder metallurgy is a manufacturing technique based on the compaction of powders that are sintered to create a solid product. This technique was used in the production of permanent magnets for the first time in the 18th century and, nowadays, most permanent magnetic materials are manufacturing by this mean. Magnetic properties are highly dependent on the microstructure of the final product, the magnetic alignment of domains and presence of porosity, to mention a few, and powder metallurgy enables fine control of these factors.

  19. High performance permanent magnet materials

    International Nuclear Information System (INIS)

    Sankar, S.G.; Herbst, J.F.; Koon, N.C.

    1987-01-01

    This book contains 25 selections. Some of the titles are: Initial magnetization behavior of rapidly quenched neodymium-iron-boron magnets; Optimization of liquid dynamic compaction for Fe-Nd-B magnet alloys; Misch-metal and/or aluminum substitutions in Nd-Fe-B permanent magnets; and NdFeB magnets with improved temperature characteristics

  20. Topology optimized permanent magnet systems

    Science.gov (United States)

    Bjørk, R.; Bahl, C. R. H.; Insinga, A. R.

    2017-09-01

    Topology optimization of permanent magnet systems consisting of permanent magnets, high permeability iron and air is presented. An implementation of topology optimization for magnetostatics is discussed and three examples are considered. The Halbach cylinder is topology optimized with iron and an increase of 15% in magnetic efficiency is shown. A topology optimized structure to concentrate a homogeneous field is shown to increase the magnitude of the field by 111%. Finally, a permanent magnet with alternating high and low field regions is topology optimized and a Λcool figure of merit of 0.472 is reached, which is an increase of 100% compared to a previous optimized design.

  1. Topology optimized permanent magnet systems

    DEFF Research Database (Denmark)

    Bjørk, Rasmus; Bahl, Christian; Insinga, Andrea Roberto

    2017-01-01

    Topology optimization of permanent magnet systems consisting of permanent magnets, high permeability iron and air is presented. An implementation of topology optimization for magnetostatics is discussed and three examples are considered. The Halbach cylinder is topology optimized with iron...... and an increase of 15% in magnetic efficiency is shown. A topology optimized structure to concentrate a homogeneous field is shown to increase the magnitude of the field by 111%. Finally, a permanent magnet with alternating high and low field regions is topology optimized and a ΛcoolΛcool figure of merit of 0...

  2. Magnetic properties of sintered high energy sm-co and nd-fe-b magnets

    Directory of Open Access Journals (Sweden)

    Talijan Nadežda M.

    2006-01-01

    Full Text Available Magnetic properties of permanent magnetic materials based on intermetallic compounds of Sm-Co and Nd-Fe-B are in direct dependence on the microstructure. In the first part of this paper, having in mind the importance of the regime of sintering and heat treatment to obtain the optimal magnetic structure, yet another approach in defining the most adequate technological parameters of the sintering process for applied heat treatment conditions was made. The goal of these investigations was to use the correlation that exists between sintering conditions (temperature and time and intensity of the diffraction peak of the (111 plane of the SmCo5 phase to optimize. In the second part a brief overview of high energy magnetic materials based on Nd-Fe-B is presented with special emphasis to the current research and development of high remanent nanocomposite magnetic materials based on Nd-Fe-B alloys with a reduced Nd content. Part of experimental results gained during research of the sintering process of SmCo5 magnetic materials were realized and published earlier. The scientific meeting devoted to the 60th anniversary of Frankel’s theory of sintering was an opportunity to show once more the importance and role of sintering in optimization of the magnetic microstructure of sintered Sm Co5 magnetic materials.

  3. Periodic permanent magnet focused klystron

    Science.gov (United States)

    Ferguson, Patrick; Read, Michael; Ives, R Lawrence

    2015-04-21

    A periodic permanent magnet (PPM) klystron has beam transport structures and RF cavity structures, each of which has permanent magnets placed substantially equidistant from a beam tunnel formed about the central axis, and which are also outside the extent of a cooling chamber. The RF cavity sections also have permanent magnets which are placed substantially equidistant from the beam tunnel, but which include an RF cavity coupling to the beam tunnel for enhancement of RF carried by an electron beam in the beam tunnel.

  4. Study of the polymer permanent magnets properties - rare earths

    International Nuclear Information System (INIS)

    Takiishi, H.; Benini, H.R.; Lima, L.F.C.P.; Faria, R.N.

    1996-01-01

    An alternative method for permanent magnet production without the sintering step is polymer bonded magnets. In this work magnets were prepared from magnetic Sm Co 5 or Nd 15 Fe 77 B 8 alloys bonded with 10% wt of resin. For the Nd 15 Fe 77 B 8 alloy the hydrogenation - decomposition - desorption - recombination (HDDR) process have been employed in the preparation of the magnets. Results from the magnetic properties showed that no milling is necessary for the production of polymer bonded Nd-Fe-B magnets. The magnets showed good magnetic properties. (author)

  5. Rare earth permanent magnet with easy magnetization

    International Nuclear Information System (INIS)

    Kim, A.S.; Camp, F.E.

    1998-01-01

    Rare earth permanent magnets have high energy products and coercivities, and thus the volume miniaturization of magnetic devices has been possible with improved magnetic performance. Although the high energy products of these rare earth permanent magnets provide substantial advantages for magnetic design and application, the strong magnetic force of the magnetized magnets makes assembly difficult. Therefore, a special device is needed to assemble the magnetized magnets. On the other hand, unmagnetized magnets are assembled and then they are magnetized. The assembled magnets are generally more difficult to magnetize than unassembled magnets because a much less effective magnetic field may be applied to them. This is particularly true for the rare earth permanent magnets because they usually need a much higher magnetic field to be fully magnetized than alnico or ferrite magnets. To obtain optimum magnetic properties, the required minimum magnetizing fields for SmCo 5 , Sm 2 TM 17 and Nd 2 Fe 14 B magnets were reported as 25-30 kOe, 45-60 kOe and 25-30 kOe, respectively. If the required magnetizing field for full saturation could be lowered, the effective utilization of magnetic properties would be maximized and the magnetic design option could be expanded with reduced restrictions. To meet this demand, we have sought to lower the field required for full magnetic saturation, and found that an increase in Dy content in R-(Fe,Co,Cu)-B type magnets lowers the field required for full saturation as well as improves the temperature stability. By increasing the H ci with Dy addition from 14 kOe to 24 and 34 kOe, the field required for full magnetic saturation decreases from about 20 to 15 and 10 kOe, respectively. This dual benefit will open up new application areas with more freedom for magnet design options. The mechanism for the lower magnetizing fields will be discussed. (orig.)

  6. Magnetic guns with cylindrical permanent magnets

    DEFF Research Database (Denmark)

    Vokoun, David; Beleggia, Marco; Heller, Luděk

    2012-01-01

    The motion of a cylindrical permanent magnet (projectile) inside a tubular permanent magnet, with both magnets magnetized axially, illustrates nicely the physical principles behind the operation of magnetic guns. The force acting upon the projectile is expressed semi-analytically as derivative...... of the magnetostatic interaction energy. For comparison, the forces involved are also calculated numerically using finite elements methods. Based on the conservation of the magnetostatic and kinetic energies, the exit and asymptotic velocities are determined. The derived formulas can be used to optimize the generated...... forces and motion of the inner cylindrical magnet....

  7. Rare earth permanent magnets

    International Nuclear Information System (INIS)

    Higuchi, Akira

    1992-01-01

    This paper is a review of the new technologies for Nd-Fe-B magnets, their markets and future perspectives. This type of magnet is a product approaching the ideal magnet, and is based upon the development history of two previous generations of Sm-Co alloy systems and the recent progress on physical and metallurgical research. (orig.)

  8. Optimally segmented permanent magnet structures

    DEFF Research Database (Denmark)

    Insinga, Andrea Roberto; Bjørk, Rasmus; Smith, Anders

    2016-01-01

    We present an optimization approach which can be employed to calculate the globally optimal segmentation of a two-dimensional magnetic system into uniformly magnetized pieces. For each segment the algorithm calculates the optimal shape and the optimal direction of the remanent flux density vector......, with respect to a linear objective functional. We illustrate the approach with results for magnet design problems from different areas, such as a permanent magnet electric motor, a beam focusing quadrupole magnet for particle accelerators and a rotary device for magnetic refrigeration....

  9. The cycloid Permanent Magnetic Gear

    DEFF Research Database (Denmark)

    Rasmussen, Peter Omand; Andersen, Torben Ole; Jørgensen, Frank T.

    2008-01-01

    This paper presents a new permanent-magnet gear based on the cycloid gearing principle. which normally is characterized by an extreme torque density and a very high gearing ratio. An initial design of the proposed magnetic gear was designed, analyzed, and optimized with an analytical model...... regarding torque density. The results were promising as compared to other high-performance magnetic-gear designs. A test model was constructed to verify the analytical model....

  10. Laced permanent magnet quadrupole drift tube magnets

    International Nuclear Information System (INIS)

    Feinberg, B.; Behrsing, G.U.; Halbach, K.; Marks, J.S.; Morrison, M.E.; Nelson, D.H.

    1988-10-01

    A laced permanent magnet quadrupole drift tube magnet has been constructed for a proof-of-principle test. The magnet is a conventional tape-wound quadrupole electromagnet, using iron pole- pieces, with the addition of permanent magnet material (neodymium iron) between the poles to reduce the effects of saturation. The iron is preloaded with magnetic flux generated by the permanent magnet material, resulting in an asymmetrical saturation curve. Since the polarity of the quadrupole magnets in a drift tube linac is not reversed we can take advantage of this asymmetrical saturation to provide greater focusing strength. The magnet configuration has been optimized and the vanadium permendur poles needed in a conventional quadrupole have been replaced with iron poles. The use of permanent magnet material has allowed us to increase the focusing strength of the magnet by about 20% over that of a conventional tape-wound quadrupole. Comparisons will be made between this magnet and the conventional tape-wound quadrupole. 3 refs., 5 figs

  11. Balancing permanent magnet arrays

    NARCIS (Netherlands)

    Krechting, P.T.; Lomonova, E.; Jansen, J.W.

    2009-01-01

    High resolution electron beam imaging (E-beam) has found wide usage in industry in photolithography and semiconductor inspection systems. E-beam inspection, which takes place in vacuum, is very sensitive to magnetic fields, and requires highly dynamic and accurate actuators Piezo "walking" motors

  12. Magnetic guns with cylindrical permanent magnets

    Czech Academy of Sciences Publication Activity Database

    Vokoun, David; Beleggia, M.; Heller, Luděk

    2012-01-01

    Roč. 324, č. 9 (2012), s. 1715-1719 ISSN 0304-8853 R&D Projects: GA ČR(CZ) GAP107/11/0391; GA AV ČR IAA100100920 Institutional research plan: CEZ:AV0Z10100520 Keywords : permanent magnet * cylindrical magnet * Earnshaw's theorem * magnetic gun * magnetostatic interaction Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.826, year: 2012 http://www.sciencedirect.com/science/article/pii/S0304885311008997

  13. Temperature dependence of domain structure of sintered SmCo5 and Smsub(0,5)Prsub(0,5)Co5 permanent magnets

    International Nuclear Information System (INIS)

    Puzanova, T.Z.; Shur, Ya.S.

    1977-01-01

    The Kerr magneto-optical effect has been used to study the domain structure morphology changes in caked SmCo 5 and Smsub(0,5)Prsub(o,5)So 5 alloy magnets at elevated temperatures in the range from 20 to 180 deg C and after protracted air annealing at temperatures from 130 to 180 deg C. The relation between the domain structure behaviour and temperature-dependent variations of magnetic properties is discussed

  14. Technological parameter effect on properties of sintered hard-magnetic type Nd-Fe-B materials

    International Nuclear Information System (INIS)

    Rastegaev, V.S.; Stepanova, G.I.; Gudim, Z.Yu.

    1989-01-01

    The effect of each technological operation on manufacturing hard magnets from Nd-Fe-B alloys on properties of sintered permanent magnets is studied. It is noted that violation of the metting regime can result in burn-up of boron and rare earths, and violation of the grinding mode-formation of nonmagnetic powder fractions, etc. Special attention is paid to material protection against oxidation by introducing passivating additions and creating of particular conditions for alloy sintering and heat treatment

  15. 21 CFR 886.4445 - Permanent magnet.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Permanent magnet. 886.4445 Section 886.4445 Food... DEVICES OPHTHALMIC DEVICES Surgical Devices § 886.4445 Permanent magnet. (a) Identification. A permanent magnet is a nonelectric device that generates a magnetic field intended to find and remove metallic...

  16. Improvement of the microstructure and magnetic properties of sintered NdFeB permant magnets

    International Nuclear Information System (INIS)

    Vial, F.; Rozendaal, E.; Sagawa, M.

    1998-01-01

    A correlation between sintered NdFeB process, microstructure of the products at each step of the process and magnetic properties has been established. To increase (BH) max of sintered NdFeB magnets, the total rare-earth content in the alloy has to be decreased and to keep coercivity as high as possible, the unavoidable oxygen pick-up has to be substantially reduced. The composition improvements tend to create a high sensitivity to form abnormal grain growth which can potentially occur during the sintering operation. Special attention has been given to characterising, understanding the mechanisms and solving this defect which could affect the magnetic properties. In addition, the composition and each step of the process have been optimised to improve magnetic properties, thermal stability and corrosion resistance of the NdFeB permanent magnets. These collaborative studies have resulted in a significant improvement of both remanence and coercivity of the sintered NdFeB permanent magnets, covering a wide coercivity range from 800 to 2500 kA/m (10 to 35 kOe) with respective associated energy products of 400 to 270 kJ/m3 (52 to 35 MGOe). (orig.)

  17. Permanent magnets including undulators and wigglers

    CERN Document Server

    Bahrdt, J

    2010-01-01

    After a few historic remarks on magnetic materials we introduce the basic definitions related to permanent magnets. The magnetic properties of the most common materials are reviewed and the production processes are described. Measurement techniques for the characterization of macroscopic and microscopic properties of permanent magnets are presented. Field simulation techniques for permanent magnet devices are discussed. Today, permanent magnets are used in many fields. This article concentrates on the applications of permanent magnets in accelerators starting from dipoles and quadrupoles on to wigglers and undulators.

  18. Study of high-coercivity sintered NdFeB magnets

    Energy Technology Data Exchange (ETDEWEB)

    Bai, G. [School of Physics and Microelectronics, Shandong University, Jinan, 250100 (China); Department of Mathematics and Physics, Xi' an Institute of Technology, Xi' an, 710032 (China); Gao, R.W. [School of Physics and Microelectronics, Shandong University, Jinan, 250100 (China)]. E-mail: gaorwbox@sdu.edu.cn; Sun, Y. [School of Physics and Microelectronics, Shandong University, Jinan, 250100 (China); Han, G.B. [School of Physics and Microelectronics, Shandong University, Jinan, 250100 (China); Wang, B. [School of Physics and Microelectronics, Shandong University, Jinan, 250100 (China); Baotou Rare Earth Research Institute, Batou 014030 (China)

    2007-01-15

    Magnetic powders for sintered NdFeB magnets have been prepared by using an advanced processing method including strip casting, hydrogen decrepitation, jet milling and rubber isotropic press. The effects of Dy, Ga and Co addition on the microstructure and magnetic properties of sintered magnets have been investigated. By adopting a suitable component ratio and adjusting proper technological parameters, we have prepared high-coercivity sintered NdFeB magnets with hard magnetic properties of {sub j} H {sub c}=25.6 kOe, B {sub r}=13.2 kG and (BH){sub max}=39.9 MGOe. The temperature coefficient of coercivity of the magnets (between 20 and 150 deg. C) is -0.53% deg. C. The magnetic properties at high temperature satisfy the needs of permanent magnet motors.

  19. Study of high-coercivity sintered NdFeB magnets

    International Nuclear Information System (INIS)

    Bai, G.; Gao, R.W.; Sun, Y.; Han, G.B.; Wang, B.

    2007-01-01

    Magnetic powders for sintered NdFeB magnets have been prepared by using an advanced processing method including strip casting, hydrogen decrepitation, jet milling and rubber isotropic press. The effects of Dy, Ga and Co addition on the microstructure and magnetic properties of sintered magnets have been investigated. By adopting a suitable component ratio and adjusting proper technological parameters, we have prepared high-coercivity sintered NdFeB magnets with hard magnetic properties of j H c =25.6 kOe, B r =13.2 kG and (BH) max =39.9 MGOe. The temperature coefficient of coercivity of the magnets (between 20 and 150 deg. C) is -0.53% deg. C. The magnetic properties at high temperature satisfy the needs of permanent magnet motors

  20. System Cost Analysis for an Interior Permanent Magnet Motor

    Energy Technology Data Exchange (ETDEWEB)

    Peter Campbell

    2008-08-01

    The objective of this program is to provide an assessment of the cost structure for an interior permanent magnet ('IPM') motor which is designed to meet the 2010 FreedomCAR specification. The program is to evaluate the range of viable permanent magnet materials for an IPM motor, including sintered and bonded grades of rare earth magnets. The study considers the benefits of key processing steps, alternative magnet shapes and their assembly methods into the rotor (including magnetization), and any mechanical stress or temperature limits. The motor's costs are estimated for an annual production quantity of 200,000 units, and are broken out into such major components as magnetic raw materials, processing and manufacturing. But this is essentially a feasibility study of the motor's electromagnetic design, and is not intended to include mechanical or thermal studies as would be done to work up a selected design for production.

  1. Permanent magnet-based MRI

    Science.gov (United States)

    Cole, David Mitchell

    1997-10-01

    The principal goal of this project is to design and build a low-cost, imaging quality permanent magnet, together with the requisite shim, gradient, and radiofrequency coils, and to integrate the magnet with an existing imaging station. There are commercial products presently available that are very similar to this imager, but information about these products is proprietary. We present here all of the details concerning the design and the manufacturing process for constructing the permanent magnet, and include suggestions for improvement. Specifically, the prototype has a mass of about 150 kilograms and is therefore portable. It's C-type geometry allows maximum access to the imaging region, which is an oblate sphere about 0.5 inches in diameter centered in a 4.7 inch air gap between two seven-inch diameter polefaces. It is hoped that this imaging magnet will serve as the prototype for a series of larger versions that will be clinically useful and affordable to physicians in developing nations. To this end, scientists in the United States and Mexico have begun to collaborate with the intention to create an MRI institute in Mexico that will train new students in this discipline, and fabricate improved imagers. The prototype resulting from this work will seed the creation of this institute, and is intended to entice students into the study of MRI by enabling hands-on interaction with an otherwise prohibitively expensive instrument.

  2. Generation of magnetic fields for accelerators with permanent magnets

    International Nuclear Information System (INIS)

    Meinander, T.

    1994-01-01

    Commercially available permanent magnet materials and their properties are reviewed. Advantages and disadvantages of using permanent magnets as compared to electromagnets for the generation of specific magnetic fields are discussed. Basic permanent magnet configurations in multipole magnets and insertion devices are presented. (orig.)

  3. Modern permanent magnetic materials - preparation and properties

    International Nuclear Information System (INIS)

    Rodewald, W.

    1989-01-01

    First of all, the basic properties of the classical (steel, AlNiCo) permanent magnetic materials and the modern rare-earth (RE) permanent magnetic materials are compared. Since the properties of RE permanent magnets depend on the particular production process, the fundamentals of the main industrial processes (powder metallurgy, rapid-solidification technique) are described and the typical properties are explained. Furthermore the production processes in development such as mechanical alloying, melt spinning technique and extrusion upsetting are briefly outlined. For applying the permanent magnets, they have to be completely magnetized. The magnetization behaviour of the various RE permanent magnets is discussed by means of the internal demagnetization curve. Finally the various influences on the temperature stability of RE permanent magnets are compiled. (orig./MM) [de

  4. Permanent magnet based dipole magnets for next generation light sources

    Directory of Open Access Journals (Sweden)

    Takahiro Watanabe

    2017-07-01

    Full Text Available We have developed permanent magnet based dipole magnets for the next generation light sources. Permanent magnets are advantageous over electromagnets in that they consume less power, are physically more compact, and there is a less risk of power supply failure. However, experience with electromagnets and permanent magnets in the field of accelerators shows that there are still challenges to replacing main magnets of accelerators for light sources with permanent magnets. These include the adjustability of the magnetic field, the temperature dependence of permanent magnets, and the issue of demagnetization. In this paper, we present a design for magnets for future light sources, supported by experimental and numerical results.

  5. A superconducting solenoid and press for permanent magnet fabrication

    International Nuclear Information System (INIS)

    Mulcahy, T. M.; Hull, J. R.

    2002-01-01

    For the first time, a superconducting solenoid (SCM) was used to increase the remnant magnetization of sintered NdFeB permanent magnets (PMs). In particular, improved magnetic alignment of commercial-grade PM powder was achieved, as it was axial die pressed into 12.7-mm diameter cylindrical compacts in the 76.2-mm warm bore of a 9-T SCM. The press used to compact the powder is unique and was specifically designed for use with the SCM. Although the press was operated in the batch mode for this proof of concept study, its design is intended to enable automated production. In operation, a simple die and punch set made of nonmagnetic materials was filled with powder and loaded into a nonmagnetic press tube. The cantilevered press tube was inserted horizontally, on a carrier manually advanced along a track, into the SCM. The robustness of the mechanical components and the SCM, in its liquid helium dewar, were specifically designed to allow for insertion and extraction of the magnetic powder and compacts, while operating at 9 T. Compaction was achieved by pressing the punches between the closed end of the press tube and the hydraulic cylinder mounted on the opposite end. Improvements up to 10% in magnetization and 20% in energy products of the permanent magnets were obtained, as the alignment fields were increased above the 2-T maximum field of the electromagnets used in industry. Increases in magnetization of 3% are significant in the mature sintered magnet industry

  6. Corrosion behaviour of Nd-Fe-B permanent magnets

    International Nuclear Information System (INIS)

    Mummert, K.; El-Aziz, A.M.; Barkleit, G.; Schultz, L.; Rodewald, W.

    2000-01-01

    The corrosion behaviour of Nd-Fe-B permanent magnetic alloys as well as of single phases of these alloys have been investigated in sulphuric acid at room temperature and humid air at 150 C using mass loss and electrochemical techniques. Scanning electron microscopy and scanning probe microscopy were used to study the surface topography. The electrostatic surface potential was examined by scanning probe microscopy using tapping mode. A correlation between the electrostatic surface potential and the corrosion rate of these alloys was found. The higher the value of the electrostatic surface potential of the intergranular phases the higher is the corrosion sensitivity. The strength of the corrosion attack on the phases of sintered permanent magnetic alloys is as follows: Ferromagnetic phase < B-rich phase < Nd-rich phase. The differences in the chemical composition as well as in the preparation of these magnetic alloys have distinct influence on the corrosion resistance of the magnetic Nd-Fe-B alloys. (orig.)

  7. Permanent Magnet Dipole for DIRAC Design Report

    CERN Document Server

    Vorozhtsov, Alexey

    2012-01-01

    Two dipole magnets including one spare unit are needed for the for the DIRAC experiment. The proposed design is a permanent magnet dipole. The design based on Sm2Co17 blocks assembled together with soft ferromagnetic pole tips. The magnet provides integrated field strength of 24.6 10-3 T×m inside the aperture of 60 mm. This Design Report summarizes the main magnetic and mechanic design parameters of the permanent dipole magnets.

  8. 3-D analysis of eddy current in permanent magnet of interior permanent magnet motors

    International Nuclear Information System (INIS)

    Kawase, Yoshihiro; Yamaguchi, Tadashi; Fukanaga, Hiromu; Ito, Shokichi

    2002-01-01

    Interior permanent magnet motors are widely used in various fields. However, in high-speed operations, it is important to decrease the eddy current loss in the permanent magnet. In order to decrease the eddy current loss, we propose to divide the permanent magnet. In this paper, we clarified the effect of division of permanent magnet on the eddy current loss using the 3-D finite element method. (Author)

  9. Influences of Laser Spot Welding on Magnetic Property of a Sintered NdFeB Magnet

    Directory of Open Access Journals (Sweden)

    Baohua Chang

    2016-08-01

    Full Text Available Laser welding has been considered as a promising method to join sintered NdFeB permanent magnets thanks to its high precision and productivity. However, the influences of laser welding on the magnetic property of NdFeB are still not clear. In the present paper, the effects of laser power on the remanence (Br were experimentally investigated in laser spot welding of a NdFeB magnet (N48H. Results show that the Br decreased with the increase of laser power. For the same welding parameters, the Br of magnets, that were magnetized before welding, were much lower than that of magnets that were magnetized after welding. The decrease in Br of magnets after laser welding resulted from the changes in microstructures and, in turn, the deterioration of magnetic properties in the nugget and the heat affected zone (HAZ in a laser weld. It is recommended that the dimensions of nuggets and HAZ in laser welds of a NdFeB permanent magnet should be as small as possible, and the magnets should be welded before being magnetized in order to achieve a better magnetic performance in practical engineering applications.

  10. Macroscopic simulation of isotropic permanent magnets

    International Nuclear Information System (INIS)

    Bruckner, Florian; Abert, Claas; Vogler, Christoph; Heinrichs, Frank; Satz, Armin; Ausserlechner, Udo; Binder, Gernot; Koeck, Helmut; Suess, Dieter

    2016-01-01

    Accurate simulations of isotropic permanent magnets require to take the magnetization process into account and consider the anisotropic, nonlinear, and hysteretic material behaviour near the saturation configuration. An efficient method for the solution of the magnetostatic Maxwell equations including the description of isotropic permanent magnets is presented. The algorithm can easily be implemented on top of existing finite element methods and does not require a full characterization of the hysteresis of the magnetic material. Strayfield measurements of an isotropic permanent magnet and simulation results are in good agreement and highlight the importance of a proper description of the isotropic material. - Highlights: • Simulations of isotropic permanent magnets. • Accurate calculation of remanence magnetization and strayfield. • Comparison with strayfield measurements and anisotropic magnet simulations. • Efficient 3D FEM–BEM coupling for solution of Maxwell equations.

  11. Nanocrystalline permanent magnets with enhanced properties

    International Nuclear Information System (INIS)

    Leonowicz, M.

    2002-01-01

    Parameters of permanent magnets result from the combination of intrinsic properties such as saturation magnetization, magnetic exchange, and magnetocrystalline energy, as well as microstructural parameters such as phase structure, grain size, and orientation. Reduction of grain size into nanocrystalline regime (∼ 50 nm) leads to the enhanced remanence which derives from ferromagnetic exchange coupling between highly refined grains. In this study the fundamental phenomena, quantities, and structure parameters, which define nanophase permanent magnets are presented and discussed. The theoretical considerations are confronted with experimental data for nanocrystalline Sm-Fe-N type permanent magnets. (author)

  12. Nonuniform radiation damage in permanent magnet quadrupoles.

    Science.gov (United States)

    Danly, C R; Merrill, F E; Barlow, D; Mariam, F G

    2014-08-01

    We present data that indicate nonuniform magnetization loss due to radiation damage in neodymium-iron-boron Halbach-style permanent magnet quadrupoles. The proton radiography (pRad) facility at Los Alamos uses permanent-magnet quadrupoles for magnifying lenses, and a system recently commissioned at GSI-Darmsdadt uses permanent magnets for its primary lenses. Large fluences of spallation neutrons can be produced in close proximity to these magnets when the proton beam is, intentionally or unintentionally, directed into the tungsten beam collimators; imaging experiments at LANL's pRad have shown image degradation with these magnetic lenses at proton beam doses lower than those expected to cause damage through radiation-induced reduction of the quadrupole strength alone. We have observed preferential degradation in portions of the permanent magnet quadrupole where the field intensity is highest, resulting in increased high-order multipole components.

  13. Nonuniform radiation damage in permanent magnet quadrupoles

    International Nuclear Information System (INIS)

    Danly, C. R.; Merrill, F. E.; Barlow, D.; Mariam, F. G.

    2014-01-01

    We present data that indicate nonuniform magnetization loss due to radiation damage in neodymium-iron-boron Halbach-style permanent magnet quadrupoles. The proton radiography (pRad) facility at Los Alamos uses permanent-magnet quadrupoles for magnifying lenses, and a system recently commissioned at GSI-Darmsdadt uses permanent magnets for its primary lenses. Large fluences of spallation neutrons can be produced in close proximity to these magnets when the proton beam is, intentionally or unintentionally, directed into the tungsten beam collimators; imaging experiments at LANL’s pRad have shown image degradation with these magnetic lenses at proton beam doses lower than those expected to cause damage through radiation-induced reduction of the quadrupole strength alone. We have observed preferential degradation in portions of the permanent magnet quadrupole where the field intensity is highest, resulting in increased high-order multipole components

  14. Nonuniform radiation damage in permanent magnet quadrupoles

    Energy Technology Data Exchange (ETDEWEB)

    Danly, C. R.; Merrill, F. E.; Barlow, D.; Mariam, F. G. [Los Alamos National Laboratory, Los Alamos, New Mexico 87544 (United States)

    2014-08-15

    We present data that indicate nonuniform magnetization loss due to radiation damage in neodymium-iron-boron Halbach-style permanent magnet quadrupoles. The proton radiography (pRad) facility at Los Alamos uses permanent-magnet quadrupoles for magnifying lenses, and a system recently commissioned at GSI-Darmsdadt uses permanent magnets for its primary lenses. Large fluences of spallation neutrons can be produced in close proximity to these magnets when the proton beam is, intentionally or unintentionally, directed into the tungsten beam collimators; imaging experiments at LANL’s pRad have shown image degradation with these magnetic lenses at proton beam doses lower than those expected to cause damage through radiation-induced reduction of the quadrupole strength alone. We have observed preferential degradation in portions of the permanent magnet quadrupole where the field intensity is highest, resulting in increased high-order multipole components.

  15. Permanent multipole magnets with adjustable strength

    International Nuclear Information System (INIS)

    Halbach, K.

    1983-01-01

    Preceded by a short discussion of the motives for using permanent magnets in accelerators, a new type of permanent magnet for use in accelerators is presented. The basic design and most important properties of a quadrople will be described that uses both steel and permanent magnet material. The field gradient produced by this magnet can be adjusted without changing any other aspect of the field produced by this quadrupole. The generalization of this concept to produce other multipole fields, or combination of multipole fields, will also be presented

  16. Permanent multipole magnets with adjustable strength

    International Nuclear Information System (INIS)

    Halbach, K.

    1983-03-01

    Preceded by a short discussion of the motives for using permanent magnets in accelerators, a new type of permanent magnet for use in accelerators is presented. The basic design and most important properties of a quadrupole will be described that uses both steel and permanent magnet material. The field gradient produced by this magnet can be adjusted without changing any other aspect of the field produced by this quadrupole. The generalization of this concept to produce other multipole fields, or combination of multipole fields, will also be presented

  17. New developments in NdFeB-based permanent magnets

    International Nuclear Information System (INIS)

    Liu, Z.W.

    2011-01-01

    NdFeB based alloys have been used as permanent magnets for almost thirty years. The recent researches aim at optimizing the composition, microstructure and properties, reducing cost, and developing new processes. The demand for sintered magnet is increasing. Efforts are directed towards improving properties by controlling grain boundary diffusion, minimizing the rare earth (RE) content and also improving production yield. As for bonded magnets, to enhance remanence and energy product, nanocrystalline powders are employed. High thermal stability has been realized by mixing NdFeB with hard ferrite powders. For nanocrystalline and nano composite NdFeB based alloys, both compositional modification and microstructural optimization have been carried out. New approaches have also been proposed to prepare NdFeB magnets with idea structure. Surfactant assisted ball milling is a good top-down method to obtain nano sized hard magnetic particles and anisotropic nano flakes. Synthesis of NdFeB nanoparticles and NdFeB/Fe (Co) nano composite powders by bottom-up techniques, such as chemical reduction process and co-precipitation, has been successful very recently. To assemble nanocrystalline NdFeB powders or nanoparticles into bulk magnets, various novel consolidation processes including spark plasma sintering and high velocity press have been employed. Hot deformation can be selected as the process to achieve anisotropy in nanocrystalline magnets. (author)

  18. Permanent magnet materials and their application

    International Nuclear Information System (INIS)

    Campbell, P.

    1994-01-01

    Permanent magnets are of great industrial importance in industrial drives, consumer products, computers, and automobiles. Since 1970, new classes of magnet materials have been developed. This book reviews the older and newer materials and is presented as a comprehensive design text for permanent magnets and their applications. After an initial chapter on the fundamentals of magnetism, the author discusses magnetic physics considerations specific to permanent magnets and describes the fabrications and characteristics of commercial materials: alnico, samarium-cobalt, ferrite, and neodymium-iron-boron. Thermal stability, magnet design procedures, magnetic field analysis methods, and measurement methods are discussed in subsequent chapters, followed by a concluding chapter reviewing commercial and industrial products that use permanent magnets. The chapter on thermal properties of magnet materials is of particular interest, bringing together information not readily found elsewhere. The review of applications is also deserving of attention, specifically the sections on motors and actuators. Although particle accelerator applications are discussed, the use of permanent magnet sextuples in modern ECR ion sources is not mentioned

  19. Magnetizing of permanent magnet using HTS bulk magnet

    International Nuclear Information System (INIS)

    Oka, Tetsuo; Muraya, Tomoki; Kawasaki, Nobutaka; Fukui, Satoshi; Ogawa, Jun; Sato, Takao; Terasawa, Toshihisa

    2011-01-01

    A demagnetized Nd-Fe-B permanent magnet was scanned just above the magnetic pole containing the HTS bulk magnet, generating a magnetic field of 3.27 T. The magnet sample was subsequently found to be fully magnetized in the open space of the static magnetic fields. We examined the magnetic field distributions when the magnetic poles were scanned twice to activate the magnetic plates inversely with various overlap distances between the tracks of the HTS bulk magnet. The magnetic field of the 'rewritten' magnet reached the values of the magnetically saturated region of the material, showing steep gradients at the border of each magnetic pole. As a replacement for conventional pulse field magnetizing methods, this technique is proposed to expand the degree of freedom in the design of electromagnetic devices, and is proposed as a novel practical method for magnetizing rare-earth magnets, which have excellent magnetic performance and require intense fields of more than 3 T to be activated. (author)

  20. Static devices with new permanent magnets

    International Nuclear Information System (INIS)

    Chavanne, J.; Laforest, J.; Pauthenet, R.

    1987-01-01

    The high remanence and coercivity of the new permanent magnet materials are of special interest in the static applications. High ordering temperature and are uniaxial anisotropy at the origin of their good permanent magnet properties are obtained in rare earth-transition metal compounds. Binary SmCo/sub 5/ and Sm/sub 2/Co/sub 17/ and ternary Nd/sub 2/Fe/sub 14/B compounds are the basis materials of the best permanent magnets. new concepts of calculations of static devices with these magnets can be applied: the magnetization can be considered as ridig, the density of the surface Amperian current is constant, the relative permeability is approximately 1 and the induction calculations are linear. Examples of hexapoles with Sm-Co and NdFeB magnets are described and the performances are compared. The problems of temperature behavior and corrosion resistance are underlined

  1. Cylindrical Hall Thrusters with Permanent Magnets

    International Nuclear Information System (INIS)

    Raitses, Yevgeny; Merino, Enrique; Fisch, Nathaniel J.

    2010-01-01

    The use of permanent magnets instead of electromagnet coils for low power Hall thrusters can offer a significant reduction of both the total electric power consumption and the thruster mass. Two permanent magnet versions of the miniaturized cylindrical Hall thruster (CHT) of different overall dimensions were operated in the power range of 50W-300 W. The discharge and plasma plume measurements revealed that the CHT thrusters with permanent magnets and electromagnet coils operate rather differently. In particular, the angular ion current density distribution from the permanent magnet thrusters has an unusual halo shape, with a majority of high energy ions flowing at large angles with respect to the thruster centerline. Differences in the magnetic field topology outside the thruster channel and in the vicinity of the channel exit are likely responsible for the differences in the plume characteristics measured for the CHTs with electromagnets and permanent magnets. It is shown that the presence of the reversing-direction or cusp-type magnetic field configuration inside the thruster channel without a strong axial magnetic field outside the thruster channel does not lead to the halo plasma plume from the CHT.

  2. Micro magnetic modeling of magnetization reversal in permanent magnets

    International Nuclear Information System (INIS)

    Toussaint, J.C.; Kevorkian, B.; Givord, D.; Rossignol, M.F.

    1996-01-01

    Micro magnetic numerical 3 D calculation is presented in this paper to investigate the effect of a soft magnetic heterogeneity on the magnetization reversal of a single hard magnetic grain. Both equilibrium and transient magnetization configurations are obtained by solving the dynamic Landau-Lifshitz-Gilbert (L.L.G.) equation. A modified forward difference method is used to integrate the time dependent L.L.G. equation without conflicting with the constraint of constant magnetic moment. A continuum view of the material medium is adopted and the spatial finite difference method is used to describe the system as a set of cubic elements. In each element the magnetization is interpolated with quadratic polynomial functions and constrained to follow the Brown condition at the surface. A multigrid approach is developed to calculate the magnetic potential and the resulting stray field associated with a given microstructure. The calculated properties are compared to actual properties of Nd Fe B sintered magnets. Assuming a soft nucleus of 160 angstrom diameter and 80 angstrom depth, the calculated coercive field is about 1.45 T, close to experimental values and the calculated angular dependence of H c resembles experimental behaviours. (author)

  3. The history of permanent magnet materials

    International Nuclear Information System (INIS)

    Livingston, J.D.

    1990-01-01

    Permanent-magnet materials play a large and growing, but largely unseen, role in today's technology. Many common devices in the home and elsewhere, including appliances, computers and printers, contain permanent-magnet motors and actuators. The growth of applications for permanent magnets results in large part from the improvements in magnetic properties, which allow the engineer to design smaller, lighter and more efficient devices. The properties of the greatest technological interest are remanence, coercivity and maximum energy product. All are non-equilibrium and high structure-sensitive. Coercivity is particularly sensitive to microstructure, while remanence is sensitive to texture (crystallographic alignment). The energy product depends on both coercivity and remanence. The more than one hundredfold increase in the available energy product in this century, and the corresponding amount of magnet required for a specific application, are shown

  4. Characterizing permanent magnet blocks with Helmholtz coils

    Science.gov (United States)

    Carnegie, D. W.; Timpf, J.

    1992-08-01

    Most of the insertion devices to be installed at the Advanced Photon Source will utilize permanent magnets in their magnetic structures. The quality of the spectral output is sensitive to the errors in the field of the device which are related to variations in the magnetic properties of the individual blocks. The Advanced Photon Source will have a measurement facility to map the field in the completed insertion devices and equipment to test and modify the magnetic strength of the individual magnet blocks. One component of the facility, the Helmholtz coil permanent magnet block measurement system, has been assembled and tested. This system measures the total magnetic moment vector of a block with a precision better than 0.01% and a directional resolution of about 0.05°. The design and performance of the system will be presented.

  5. Dovetail spoke internal permanent magnet machine

    Science.gov (United States)

    Alexander, James Pellegrino [Ballston Lake, NY; EL-Refaie, Ayman Mohamed Fawzi [Niskayuna, NY; Lokhandwalla, Murtuza [Clifton Park, NY; Shah, Manoj Ramprasad [Latham, NY; VanDam, Jeremy Daniel [West Coxsackie, NY

    2011-08-23

    An internal permanent magnet (IPM) machine is provided. The IPM machine includes a stator assembly and a stator core. The stator core also includes multiple stator teeth. The stator assembly is further configured with stator windings to generate a stator magnetic field when excited with alternating currents and extends along a longitudinal axis with an inner surface defining a cavity. The IPM machine also includes a rotor assembly and a rotor core. The rotor core is disposed inside the cavity and configured to rotate about the longitudinal axis. The rotor assembly further includes a shaft. The shaft further includes multiple protrusions alternately arranged relative to multiple bottom structures provided on the shaft. The rotor assembly also includes multiple stacks of laminations disposed on the protrusions and dovetailed circumferentially around the shaft. The rotor assembly further includes multiple pair of permanent magnets for generating a magnetic field, which magnetic field interacts with the stator magnetic field to produce a torque. The multiple pair of permanent magnets are disposed between the stacks. The rotor assembly also includes multiple middle wedges mounted between each pair of the multiple permanent magnets.

  6. Analysis of a spherical permanent magnet actuator

    International Nuclear Information System (INIS)

    Wang, J.; Jewell, G.W.; Howe, D.

    1997-01-01

    This paper describes a new form of actuator with a spherical permanent magnet rotor and a simple winding arrangement, which is capable of a high specific torque by utilizing a rare-earth permanent magnet. The magnetic-field distribution is established using an analytical technique formulated in spherical coordinates, and the results are validated by finite element analysis. The analytical field solution allows the prediction of the actuator torque and back emf in closed forms. In turn, these facilitate the characterization of the actuator and provide a firm basis for design optimization, system dynamic modeling, and closed-loop control law development. copyright 1997 American Institute of Physics

  7. Comparing superconducting and permanent magnets for magnetic refrigeration

    DEFF Research Database (Denmark)

    Bjørk, Rasmus; Nielsen, Kaspar Kirstein; Bahl, C. R. H.

    2016-01-01

    We compare the cost of a high temperature superconducting (SC) tape-based solenoidwith a permanent magnet (PM) Halbach cylinder for magnetic refrigeration.Assuming a five liter active magnetic regenerator volume, the price of each type ofmagnet is determined as a function of aspect ratio...... of the regenerator and desiredinternal magnetic field. It is shown that to produce a 1 T internal field in theregenerator a permanent magnet of hundreds of kilograms is needed or an area ofsuperconducting tape of tens of square meters. The cost of cooling the SC solenoidis shown to be a small fraction of the cost...... of the SC tape. Assuming a cost ofthe SC tape of 6000 $/m2 and a price of the permanent magnet of 100 $/kg, thesuperconducting solenoid is shown to be a factor of 0.3-3 times more expensive thanthe permanent magnet, for a desired field from 0.5-1.75 T and the geometrical aspectratio of the regenerator...

  8. Design and construction of permanent magnetic gears

    DEFF Research Database (Denmark)

    Jørgensen, Frank Thorleif

    /l]. Measurement from this gear has resulted in a measured total torque density of 23 [Nm/l]. Mechanical versions of this gear type are found with total torque density in the 16 to 31 [Nm/l] range. The third and last gear technology that is investigated is a gear that reminds of a planetary gear. Research shows......This thesis deals with design and development of permanent magnetic gears. The goal of this thesis is to develop knowledge and calculation software for magnetic gears. They use strong NdFeB permanent magnets and a new magnetic gear technology, which will be a serious alternative to classical...... mechanical gears. The new magnetic gear will have a high torque density1 relationship –high efficiency and are maintenance free. In this project was manufactured two test gears which is tested and verified with models developed in this project. Present technological status for magnetic gears is introduced...

  9. High-field permanent-magnet structures

    International Nuclear Information System (INIS)

    Leupoid, H.A.

    1989-01-01

    This patent describes a permanent magnet structure. It comprises an azimuthally circumscribed section of a hollow hemispherical magnetic flux source, the magnetic orientation in the section with respect to the polar axis being substantially equal to twice the polar angle, a superconducting planar sheet abutting one flat face of the section along a longitudinal meridian, and at least one other planar sheet of selected material abutting another flat face of the section and perpendicular to the first-mentioned sheet

  10. Superconducting permanent magnets and their application in magnetic levitation

    International Nuclear Information System (INIS)

    Schultz, L.; Krabbes, G.; Fuchs, G.; Pfeiffer, W.; Mueller, K.H.

    2002-01-01

    Superconducting permanent magnets form a completely new class of permanent magnets. Of course, they must be cooled to 77 K or below. At very low temperatures (24 K) their magnetization can be a factor of 10 higher than that of the best conventional magnets, providing magnetic forces and energies which are up to two orders of magnitude higher. These new supermagnets became only recently available by the extreme improvement of the quality of melt-textured massive YBa 2 Cu 3 O x samples. Besides having a high magnetization, these superconducting permanent magnets can freeze in any given magnetic field configuration allowing completely new applications like superconducting transport systems or superconducting magnetic bearings. (orig.)

  11. Magnetic shielding for coreless linear permanent magnet motors

    NARCIS (Netherlands)

    Pluk, K.J.W.; Jansen, J.W.; Lomonova, E.

    2013-01-01

    This paper concerns the local reduction of the magnetic flux density by means of magnetic shielding. Using a spatial frequency description, a 2-D semi-analytical periodic model is obtained for a coreless single-sided linear permanent magnet motor. The magnetic shield is included in the modeling

  12. Dysprosium-free melt-spun permanent magnets

    International Nuclear Information System (INIS)

    Brown, D N; Wu, Z; He, F; Miller, D J; Herchenroeder, J W

    2014-01-01

    Melt-spun NdFeB powders can be formed into a number of different types of permanent magnet for a variety of applications in electronics, automotive and clean technology industries. The melt-spinning process produces flake powder with a fine uniform array of nanoscale Nd 2 Fe 14 B grains. These powders can be net-shape formed into isotropic polymer-bonded magnets or hot formed into fully dense magnets. This paper discusses the influence of heavy rare earth elements and microstructure on the magnetic performance, thermal stability and material cost of NdFeB magnets. Evidence indicates that melt-spun nanocrystalline NdFeB magnets are less dependent on heavy rare earth elements for high-temperature performance than the alternative coarser-grained sintered NdFeB magnets. In particular, hot-pressed melt-spun magnets are an attractive low-cost solution for applications that require thermal stability up to 175–200 °C. (paper)

  13. Dysprosium-free melt-spun permanent magnets.

    Science.gov (United States)

    Brown, D N; Wu, Z; He, F; Miller, D J; Herchenroeder, J W

    2014-02-12

    Melt-spun NdFeB powders can be formed into a number of different types of permanent magnet for a variety of applications in electronics, automotive and clean technology industries. The melt-spinning process produces flake powder with a fine uniform array of nanoscale Nd2Fe14B grains. These powders can be net-shape formed into isotropic polymer-bonded magnets or hot formed into fully dense magnets. This paper discusses the influence of heavy rare earth elements and microstructure on the magnetic performance, thermal stability and material cost of NdFeB magnets. Evidence indicates that melt-spun nanocrystalline NdFeB magnets are less dependent on heavy rare earth elements for high-temperature performance than the alternative coarser-grained sintered NdFeB magnets. In particular, hot-pressed melt-spun magnets are an attractive low-cost solution for applications that require thermal stability up to 175-200 °C.

  14. Development of cryogenic permanent magnet undulator

    International Nuclear Information System (INIS)

    Hara, Toru; Tanaka, Takashi; Shirasawa, Katsutoshi; Kitamura, Hideo; Bizen, Teruhiko; Seike, Takamitsu; Marechal, Xavier; Tsuru, Rieko; Iwaki, Daisuke

    2005-01-01

    A short period undulator increases not only the photon energy of undulator radiation, but also the brilliance due to its increased number of undulator periods. As a result, brilliant undulator radiation becomes available in the photon energy range, which is currently covered by wigglers. In order to develop a short period undulator, high performance magnets are indispensable and superconductive undulators have been actively investigated in recent years. In this paper, however, we propose a new approach, so called a cryogenic permanent magnet undulator using NdFeB magnets at the temperatures around 150 K. The current status of this cryogenic permanent magnet undulator development at SPring-8 is presented including the results of the magnetic field measurements on a prototype undulator. (author)

  15. Regulation of fields excited by permanent magnets

    International Nuclear Information System (INIS)

    Savchenko, I.S.

    1989-01-01

    Two methods of fast regulation of fields excited by permanent magnets in salient-pole electron-optical lenses are described: 1)the hybrid method realized using the additional electromagnet introduced to a magnetic chain sequentially its field being composed or substracted with magnetosolid exciter field; 2)the method with saturation of a part of a magnetic circuit, with saturation being achievable at the begining or in the end of a regulation cycle. In the second method it is proposed to direct orthogonally the main flux excited by permanent magnets and the flux in the saturated part of the magnetic circuit excited using an electromagnet. It is shown that the second method allows one to reduce the required ampere-coils by more than an order as compared to the first method at one and the same regulation range and other equal conditions. The frequency of field regulation in the experimental mock-up was 10 kHz. 3 refs.; 2 figs

  16. Analysis of Hall Probe Precise Positioning with Cylindrical Permanent Magnet

    International Nuclear Information System (INIS)

    Belicev, P.; Vorozhtsov, A.S.; Vorozhtsov, S.B.

    2007-01-01

    Precise positioning of a Hall probe for cyclotron magnetic field mapping, using cylindrical permanent magnets, was analyzed. The necessary permanent magnet parameters in order to achieve ±20 μm position precision, were determined. (author)

  17. Tuning permanent magnets with adjustable field clamps

    International Nuclear Information System (INIS)

    Schermer, R.I.

    1987-01-01

    The effective length of a permanent-magnet assembly can be varied by adjusting the geometrical parameters of a field clamp. This paper presents measurements on a representative dipole and quadrupole as the field clamp is withdrawn axially or radially. The detailed behavior depends upon the magnet multipolarity and geometry. As a rule-of-thumb, a 3-mm-thick iron plate placed at one end plane of the magnet will shorten the length by one-third of the magnet bore radius

  18. Tubular permanent magnet actuators: cogging forces characterization

    NARCIS (Netherlands)

    Paulides, J.J.H.; Janssen, J.L.G.; Encica, L.; Lomonova, E.A.

    2009-01-01

    Tubular permanent magnet actuators are evermore used in demanding industrial and automotive applications. However, these actuators can suffer from large cogging forces, which have a destabilizing effect on the servo control system and compromise position and speed control accuracy. This paper

  19. resonant inverter supplied interior permanent magnet (ipm)

    African Journals Online (AJOL)

    user

    [5] Zhenyue Hong, “DC-voltage link resonant inverters”, Department of Electrical and. Electronic Engineering University of. Canterbury, New Zealand. [6] Kalyan Kumar Halder, Naruttam Kumar Roy and B.C. Ghosh, “Position Sensorless. Control for an Interior Permanent Magnet. Synchronous Motor SVM Drive with ANN.

  20. Permanent magnet motor technology design and applications

    CERN Document Server

    Gieras, Jacek F

    2009-01-01

    Demonstrates the construction of permanent magnet (PM) motor drives and supplies ready-to-implement solutions to common roadblocks along the way. This book also supplies fundamental equations and calculations for determining and evaluating system performance, efficiency, reliability, and cost. It explores modern computer-aided design of PM motors.

  1. Constant force linear permanent magnet actuators

    NARCIS (Netherlands)

    Paulides, J.J.H.; Encica, L.; Meessen, K.J.; Lomonova, E.A.

    2009-01-01

    In applications, such as vibration isolation, gravity compensation, pick-and-place machines, etc., there is a need for (long-stroke) passive constant force actuators combined with tubular permanent magnet actuators to minimize the power consumption, hence, passively counteract the gravitational

  2. Forces Between a Permanent Magnet and a Soft Magnetic Plate

    DEFF Research Database (Denmark)

    Beleggia, Marco; Vokoun, David; De Graef, Marc

    2012-01-01

    Forces between a hard/permanent magnet of arbitrary shape and an ideally soft magnetic plate in close proximity are derived analytically from the image method applied to magnetostatics. We found that the contact force, defined as the force required to detach the hard magnet from the plate, coinci...

  3. Magnetic forces between arrays of cylindrical permanent magnets

    Czech Academy of Sciences Publication Activity Database

    Vokoun, David; Tomassetti, G.; Beleggia, M.; Stachiv, Ivo

    2011-01-01

    Roč. 323, č. 1 (2011), s. 55-60 ISSN 0304-8853 R&D Projects: GA ČR(CZ) GA101/09/0702 Institutional research plan: CEZ:AV0Z10100520 Keywords : magnetism * permanent magnets Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.780, year: 2011

  4. Permanent Magnet Eddy Current Loss Analysis of a Novel Motor Integrated Permanent Magnet Gear

    DEFF Research Database (Denmark)

    Zhang, Yuqiu; Lu, Kaiyuan; Ye, Yunyue

    2012-01-01

    In this paper, a new motor integrated permanent magnet gear (MIPMG) is discussed. The focus is on eddy current loss analysis associated to permanent magnets (PMs). A convenient model of MIPMG is provided based on 2-D field-motion coupled time-stepping finite element method for transient eddy...... current analysis. The model takes the eddy current effect of PMs into account in determination of the magnetic field in the air-gap and in the magnet regions. The eddy current losses generated in the magnets are properly interpreted. Design improvements for reducing the eddy current losses are suggested...

  5. A Review of Permanent Magnet Stirring During Metal Solidification

    Science.gov (United States)

    Zeng, Jie; Chen, Weiqing; Yang, Yindong; Mclean, Alexander

    2017-12-01

    Rather than using conventional electromagnetic stirring (EMS) with three-phase alternating current, permanent magnet stirring (PMS), based on the use of sintered NdFeB material which has excellent magnetic characteristics, can be employed to generate a magnetic field for the stirring of liquid metal during solidification. Recent experience with steel casting indicates that PMS requires less than 20 pct of the total energy compared with EMS. Despite the excellent magnetic density properties and low power consumption, this relatively new technology has received comparatively little attention by the metal casting community. This paper reviews simulation modeling, experimental studies, and industrial trials of PMS conducted during recent years. With the development of magnetic simulation software, the magnetic field and associated flow patterns generated by PMS have been evaluated. Based on the results obtained from laboratory experiments, the effects of PMS on metal solidification structures and typical defects such as surface pinholes and center cavities are summarized. The significance of findings obtained from trials of PMS within the metals processing sector, including the continuous casting of steel, are discussed with the aim of providing an overview of the relevant parameters that are of importance for further development and industrial application of this innovative technology.

  6. A permanent magnet system for Kibble balances

    Science.gov (United States)

    Li, Shisong; Bielsa, Franck; Stock, Michael; Kiss, Adrien; Fang, Hao

    2017-10-01

    The magnet is one of the fundamental elements in Kibble balances. The Kibble balance group at the Bureau International des Poids et Mesures (BIPM) proposed a permanent magnet with a radial field, which has been widely employed in other Kibble balance experiments. In this paper, we discuss a different method of operation for the BIPM-type magnet, i.e. only the lower half of the magnetic circuit is closed. The merit of such a magnet is its convenience for opening the air gap and adjusting the coil. A disadvantage is that it can yield a lower and sloped magnetic field profile with less shielding. In the approach described, high permeability yokes are used to flatten the magnetic profile, which has proven to be a novel and convenient approach for removing the nonuniformity of the magnetic profile due to magnet magnetization asymmetries. The performance of the half-closed BIPM magnet is evaluated using experimental measurements. The results show that the half-closed magnetic circuit retains most of the main features of the fully-closed magnet and is a good option for the early stages of Kibble balance operations. In addition, the profile change due to the coil current is predicted and experimentally verified with a bifilar coil. Related systematic effects are discussed for the Planck constant measurement.

  7. Application of permanent magnets made from NdFeB powder and from mixtures of powders in DC motors

    International Nuclear Information System (INIS)

    Slusarek, B.; Dudzikowski, I.

    2002-01-01

    The paper presents the influence of magnetic properties of applied permanent magnets on the characteristics of DC motors excited with these magnets. In the factory-produced DC motors, excited with sintered ferrite magnets, authors replaced ferrite magnets with the dielectromagnets from NdFeB powder and from different mixtures of NdFeB and ferrite powders. The paper shows the increase of the power of the resultant DC motors according to the powders' content

  8. Permanent magnet design for high-speed superconducting bearings

    Science.gov (United States)

    Hull, John R.; Uherka, Kenneth L.; Abdoud, Robert G.

    1996-01-01

    A high temperature superconducting bearing including a permanent magnet rotor levitated by a high temperature superconducting structure. The rotor preferably includes one or more concentric permanent magnet rings coupled to permanent magnet ring structures having substantially triangular and quadrangular cross-sections. Both alternating and single direction polarity magnet structures can be used in the bearing.

  9. Permanent magnet design for high-speed superconducting bearings

    International Nuclear Information System (INIS)

    Hull, J.R.; Uherka, K.L.; Abdoud, R.G.

    1996-01-01

    A high temperature superconducting bearing including a permanent magnet rotor levitated by a high temperature superconducting structure is disclosed. The rotor preferably includes one or more concentric permanent magnet rings coupled to permanent magnet ring structures having substantially triangular and quadrangular cross-sections. Both alternating and single direction polarity magnet structures can be used in the bearing. 9 figs

  10. Current status and future outlook for bonded neodymium permanent magnets (invited)

    International Nuclear Information System (INIS)

    Croat, J.J.

    1997-01-01

    Bonded neodymium magnets can provide significant size and weight reduction and/or performance enhancement over sintered and, particularly, bonded ferrite permanent magnets and, moreover, provide these benefits at reasonable cost. Primarily for these reasons, these bonded magnets are now used in a wide and growing range of computer peripheral, office automation, and consumer electronic applications and now constitute the fastest growing segment of the permanent magnet market. The current status of these materials will be reviewed. Included is a brief overview of the manufacture of these magnetically isotropic magnets and a discussion of their unique properties and features from the perspective of both bonded magnet producer and user. Major applications are discussed as are some of the factors that will drive the market for these materials in the future. New technical developments, including the status and outlook for anisotropic bonded materials, high remanance isotropic materials and high temperature bonded magnets will also be discussed. copyright 1997 American Institute of Physics

  11. Sensorless Control of Permanent Magnet Synchronous Machines

    DEFF Research Database (Denmark)

    Matzen, Torben N.

    Permanent magnet machines, with either surface mounted or embedded magnets on the rotor, are becoming more common due to the key advantages of higher energy conversion efficiency and higher torque density compared to the classical induction machine. Besides energy efficiency the permanent magnet...... the synchronous machine requires knowledge of the rotor shaft position due to the synchronous and undamped nature of the machine. The rotor position may be measured using a mechanical sensor, but the sensor reduces reliability and adds cost to the system and for this reason sensorless control methods started...... are dependent on the phase currents and rotor position. Based on the flux linkages the differential inductances are determined and used to establish the inductance saliency in terms of ratio and orientation. The orientation and its dependence on the current and rotor position are used to analyse the behaviour...

  12. Tunable high-gradient permanent magnet quadrupoles

    CERN Document Server

    Shepherd, B J A; Marks, N; Collomb, N A; Stokes, D G; Modena, M; Struik, M; Bartalesi, A

    2014-01-01

    A novel type of highly tunable permanent magnet (PM) based quadrupole has been designed by the ZEPTO collaboration. A prototype of the design (ZEPTO-Q1), intended to match the specification for the CLIC Drive Beam Decelerator, was built and magnetically measured at Daresbury Laboratory and CERN. The prototype utilises two pairs of PMs which move in opposite directions along a single vertical axis to produce a quadrupole gradient variable between 15 and 60 T/m. The prototype meets CLIC's challenging specification in terms of the strength and tunability of the magnet.

  13. Permanent-magnet-less synchronous reluctance system

    Science.gov (United States)

    Hsu, John S

    2012-09-11

    A permanent magnet-less synchronous system includes a stator that generates a magnetic revolving field when sourced by an alternating current. An uncluttered rotor is disposed within the magnetic revolving field and spaced apart from the stator to form an air gap relative to an axis of rotation. The rotor includes a plurality of rotor pole stacks having an inner periphery biased by single polarity of a north-pole field and a south-pole field, respectively. The outer periphery of each of the rotor pole stacks are biased by an alternating polarity.

  14. Magnetic properties of high temperature superconductors and their interaction with high energy permanent magnets

    International Nuclear Information System (INIS)

    Agarwala, A.K.

    1990-01-01

    Magnetic properties of sintered samples of YBCO ceramic superconductors at various temperatures were measured using a vibrating sample magnetometer (VSM). Also, measurements of forces experienced by a well characterized rare earth-transition metal (RE-TM) permanent magnet (PM) interacting with the superconducting YBCO sample cooled in liquid nitrogen, were performed. Based upon the observed hysteretic magnetization properties of these high temperature superconductors (HTS), the HTS-PM interaction force at liquid nitrogen temperature was calculated from first principle, and finally correlated to the force measurement results. With this analysis, magnetic forces between the same HTS and PM system including the levitation as well as suspension effects at liquid-helium temperature are predicted

  15. Variable high gradient permanent magnet quadrupole (QUAPEVA)

    Science.gov (United States)

    Marteau, F.; Ghaith, A.; N'Gotta, P.; Benabderrahmane, C.; Valléau, M.; Kitegi, C.; Loulergue, A.; Vétéran, J.; Sebdaoui, M.; André, T.; Le Bec, G.; Chavanne, J.; Vallerand, C.; Oumbarek, D.; Cosson, O.; Forest, F.; Jivkov, P.; Lancelot, J. L.; Couprie, M. E.

    2017-12-01

    Different applications such as laser plasma acceleration, colliders, and diffraction limited light sources require high gradient quadrupoles, with strength that can reach up to 200 T/m for a typical 10 mm bore diameter. We present here a permanent magnet based quadrupole (so-called QUAPEVA) composed of a Halbach ring and surrounded by four permanent magnet cylinders. Its design including magnetic simulation modeling enabling us to reach 201 T/m with a gradient variability of 45% and mechanical issues are reported. Magnetic measurements of seven systems of different lengths are presented and confirmed the theoretical expectations. The variation of the magnetic center while changing the gradient strength is ±10 μm. A triplet of QUAPEVA magnets is used to efficiently focus a beam with large energy spread and high divergence that is generated by a Laser Plasma Acceleration source for a free electron laser demonstration and has enabled us to perform beam based alignment and control the dispersion of the beam.

  16. Robotized Surface Mounting of Permanent Magnets

    Directory of Open Access Journals (Sweden)

    Erik Hultman

    2014-10-01

    Full Text Available Using permanent magnets on a rotor can both simplify the design and increase the efficiency of electric machines compared to using electromagnets. A drawback, however, is the lack of existing automated assembly methods for large machines. This paper presents and motivates a method for robotized surface mounting of permanent magnets on electric machine rotors. The translator of the Uppsala University Wave Energy Converter generator is used as an example of a rotor. The robot cell layout, equipment design and assembly process are presented and validated through computer simulations and experiments with prototype equipment. A comparison with manual assembly indicates substantial cost savings and an improved work environment. By using the flexibility of industrial robots and a scalable equipment design, it is possible for this assembly method to be adjusted for other rotor geometries and sizes. Finally, there is a discussion on the work that remains to be done on improving and integrating the robot cell into a production line.

  17. Permanent-magnet switched-flux machine

    Science.gov (United States)

    Trzynadlowski, Andrzej M.; Qin, Ling

    2010-01-12

    A permanent-magnet switched-flux (PMSF) device has a ferromagnetic outer stator mounted to a shaft about a central axis extending axially through the PMSF device. Pluralities of top and bottom stator poles are respectively mounted in first and second circles, radially outwardly in first and second transverse planes extending from first and second sections of the central axis adjacent to an inner surface of the ferromagnetic outer stator. A ferromagnetic inner rotor is coupled to the shaft and has i) a rotor core having a core axis co-axial with the central axis; and ii) first and second discs having respective outer edges with first and second pluralities of permanent magnets (PMs) mounted in first and second circles, radially outwardly from the rotor core axis in the first and second transverse planes. The first and second pluralities of PMs each include PMs of alternating polarity.

  18. Didactic Considerations on Magnetic Circuits Excited by Permanent Magnets

    Science.gov (United States)

    Barmada, S.; Rizzo, R.; Sani, L.

    2009-01-01

    In this paper, the authors focus their attention on the way magnetic circuits and permanent magnets are usually treated in most textbooks and electrical engineering courses. This paper demonstrates how this important topic is too often presented simplistically. This simplistic treatment does not allow the students to develop a complete…

  19. Comparing superconducting and permanent magnets for magnetic refrigeration

    Directory of Open Access Journals (Sweden)

    R. Bjørk

    2016-05-01

    Full Text Available We compare the cost of a high temperature superconducting (SC tape-based solenoid with a permanent magnet (PM Halbach cylinder for magnetic refrigeration. Assuming a five liter active magnetic regenerator volume, the price of each type of magnet is determined as a function of aspect ratio of the regenerator and desired internal magnetic field. It is shown that to produce a 1 T internal field in the regenerator a permanent magnet of hundreds of kilograms is needed or an area of superconducting tape of tens of square meters. The cost of cooling the SC solenoid is shown to be a small fraction of the cost of the SC tape. Assuming a cost of the SC tape of 6000 $/m2 and a price of the permanent magnet of 100 $/kg, the superconducting solenoid is shown to be a factor of 0.3-3 times more expensive than the permanent magnet, for a desired field from 0.5-1.75 T and the geometrical aspect ratio of the regenerator. This factor decreases for increasing field strength, indicating that the superconducting solenoid could be suitable for high field, large cooling power applications.

  20. Magnetic forces between arrays of cylindrical permanent magnets

    DEFF Research Database (Denmark)

    Vokoun, D.; Tomassetti, G.; Beleggia, Marco

    2011-01-01

    procedures. Here, we introduce analytical expressions for calculating the attraction force between two arrays of cylindrical permanent magnets and compare the predictions with experimental data obtained from force measurements with NdFeB magnets. We show that the difference between predicted and measured...

  1. Axial flux permanent magnet brushless machines

    CERN Document Server

    Gieras, Jacek F; Kamper, Maarten J

    2008-01-01

    Axial Flux Permanent Magnet (AFPM) brushless machines are modern electrical machines with a lot of advantages over their conventional counterparts. They are being increasingly used in consumer electronics, public life, instrumentation and automation system, clinical engineering, industrial electromechanical drives, automobile manufacturing industry, electric and hybrid electric vehicles, marine vessels and toys. They are also used in more electric aircrafts and many other applications on larger scale. New applications have also emerged in distributed generation systems (wind turbine generators

  2. Plasma sprayed samarium--cobalt permanent magnets

    International Nuclear Information System (INIS)

    Willson, M.C.; Janowiecki, R.J.

    1975-01-01

    Samarium--cobalt permanent magnets were fabricated by arc plasma spraying. This process involves the injection of relatively coarse powder particles into a high-temperature gas for melting and spraying onto a substrate. The technique is being investigated as an economical method for fabricating cobalt--rare earth magnets for advanced traveling wave tubes and cross-field amplifiers. Plasma spraying permits deposition of material at high rates over large areas with optional direct bonding to the substrate, and offers the ability to fabricate magnets in a variety of shapes and sizes. Isotropic magnets were produced with high coercivity and good reproducibility in magnetic properties. Post-spray thermal treatments were used to enhance the magnetic properties of sprayed deposits. Samarium--cobalt magnets, sprayed from samarium-rich powder and subjected to post-spray heat treatment, displayed energy products in excess of 9 million gauss-oersteds and coercive forces of approximately 6000 oersteds. Bar magnet arrays were constructed by depositing magnets on ceramic substrates. (auth)

  3. Plasma sprayed samarium--cobalt permanent magnets

    International Nuclear Information System (INIS)

    Willson, M.C.; Janowiecki, R.J.

    1975-01-01

    Samarium--Co permanent magnets were fabricated by arc plasma spraying. This process involves the injection of relatively coarse powder particles into a high temperature gas for melting and spraying onto a substrate. The technique is being investigated as an economical method for fabricating Co--rare earth magnets for advanced traveling wave tubes and cross-field amplifiers. Plasma spraying permits deposition of material at high rates over large areas with optional direct bonding to the substrate, and offers the ability to fabricate magnets in a variety of shapes and sizes. Isotropic magnets were produced with high coercivity and good reproducibility in magnetic properties. Post-spray thermal treatments were used to enhance the magnetic properties of sprayed deposits. Samarium--Co magnets, sprayed from Sm-rich powder and subjected to post-spray heat treatment, displayed energy products in excess of 9 million G-Oe and coercive forces of approximately 6000 Oe. Bar magnet arrays were constructed by depositing magnets on ceramic substrates

  4. Finite element analysis of permanent magnet motors

    International Nuclear Information System (INIS)

    Boglietti, A.; Chiampi, M.; Tartaglia, M.; Chiarabaglio, D.

    1989-01-01

    The analysis of permanent magnet D.C. brushless motors, supplied by current control inverters, is developed employing a finite element package tailored for such devices. The study is devoted to predicting the performance of a set of four poles machines, under different operating conditions (no-load, rated load). The over-load conditions are also considered including the saturation effect. Moreover the influence of such design parameters, as the tooth shape and the number of magnet segments, is investigated. Computed results are found in satisfactory agreement with experimental ones

  5. Automatic design of permanent magnet coupling

    International Nuclear Information System (INIS)

    Yonnet, J.-P.; Pandele, P.; Coutel, C.; Wurtz, F.

    1998-01-01

    Up to now, two main methods have been used to design permanent magnet couplings : finite element calculation, and analytical expressions of the forces between the magnets. The two methods use the same starting point, the permanent magnet coupling dimensions. The calculated parameters are the forces and the torques. The optimization of the couplings shape is generally done by using different curves describing torque variations as a function of the different geometrical parameters. We have developed a very new approach solving the reverse problem. Choosing the value of the torque, the airgap and an optimization criterium, the new method automatically calculates the size of the magnets and the ideal number of poles. It is based on a software, PASCOSMA, using an analytical model of the coupling which can be eventually corrected by a finite element method like FLUX2D. The coupling optimization is automatically made, keeping the parameters between predefined values. For a given application, it is very easy to obtain the best design, for example with the minimum magnet volume. (orig.)

  6. Forces between permanent magnets: experiments and model

    International Nuclear Information System (INIS)

    González, Manuel I

    2017-01-01

    This work describes a very simple, low-cost experimental setup designed for measuring the force between permanent magnets. The experiment consists of placing one of the magnets on a balance, attaching the other magnet to a vertical height gauge, aligning carefully both magnets and measuring the load on the balance as a function of the gauge reading. A theoretical model is proposed to compute the force, assuming uniform magnetisation and based on laws and techniques accessible to undergraduate students. A comparison between the model and the experimental results is made, and good agreement is found at all distances investigated. In particular, it is also found that the force behaves as r −4 at large distances, as expected. (paper)

  7. Experience with the SLC permanent magnet multipoles

    International Nuclear Information System (INIS)

    Gross, G.; Spencer, J.

    1994-06-01

    Permanent magnets have been used in the SLC Damping Rings and their injection and extraction lines since 1985. Recent upgrades of the DR vacuum chambers provided an opportunity to check DR magnets prior to higher beam current operation. Several PM sextupoles downstream of the injection kickers in the electron ring had exceeded their thermal stabilization values of 80 degrees C and some showed serious mechanical deformations and radiation >1 R at contact. We discuss our observations, measurements and a few inexpensive modifications that should improve these magnets under such conditions. A new, block matching algorithm allowed us to use magnet blocks that had been considered unusable because of very different remament field strengths and easy axis errors

  8. Magnetic microstructure and magnetic properties of spark plasma sintered NdFeB magnets

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Y.L., E-mail: hyl1019_lin@163.com [School of Materials Science and Engineering, Nanchang Hangkong University, Nanchang 330063 (China); Wang, Y.; Hou, Y.H.; Wang, Y.L.; Wu, Y.; Ma, S.C. [School of Materials Science and Engineering, Nanchang Hangkong University, Nanchang 330063 (China); Liu, Z.W.; Zeng, D.C. [School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640 (China); Tian, Y.; Xia, W.X. [Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Material Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); Zhong, Z.C., E-mail: zzhong2014@sina.com [School of Materials Science and Engineering, Nanchang Hangkong University, Nanchang 330063 (China)

    2016-02-01

    Nanocrystalline NdFeB magnets were prepared by spark plasma sintering (SPS) technique using melt-spun ribbons as starting materials. A distinct two-zone structure with coarse grain zone and fine grain zone was formed in the SPSed magnets. Multi-domain particle in coarse grain zone and exchange interaction domain for fine grain zone were observed. Intergranular non-magnetic phase was favorable to improve the coercivity due to the enhancement of domain wall pinning effects and increased exchange-decouple. The remanent polarization of 0.83 T, coercivity of 1516 kA/m, and maximum energy product of 118 kJ/m{sup 3} are obtained for an isotropic magnet. - Highlights: • Nanocrystalline NdFeB magnets were prepared by spark plasma sintering technique. • Multi-domain particle and exchange interaction domain were observed. • Magnetic microstructure and their relation to the properties were investigated.

  9. Discussions on performance of two types of permanent multipole magnets

    International Nuclear Information System (INIS)

    Xu Jianming; Xu Qing; Yin Zhaosheng

    1987-01-01

    The field distributions of MMD type and MW type multipole permanent magnets are calculated by means of programme POISCR and the results are summarized and discussed in this paper. The resutls show that, considering the nonlinearity of the real demagnetization curve of permanent magnet material, the field distributions of both types of permanent magnets with the same aperature are about the same but the field strength of MW type magnet with soft iron shield is higher than that of MMD type magnet

  10. A rotary permanent magnet magnetic refrigerator based on AMR cycle

    International Nuclear Information System (INIS)

    Aprea, C.; Cardillo, G.; Greco, A.; Maiorino, A.; Masselli, C.

    2016-01-01

    Magnetic refrigeration is an emerging, environment-friendly technology based on a magnetic solid that acts as a refrigerant by magneto-caloric effect (MCE). The reference cycle for magnetic refrigeration is AMR (Active Magnetic Regenerative refrigeration). In order to demonstrate the potential of magnetic refrigeration to provide useful cooling in the near room temperature range, a novel Rotary Permanent Magnet Magnetic Refrigerator (RPMMR) is described in this paper. Gadolinium has been selected as magnetic refrigerant and demineralized water has been employed as regenerating fluid. The total mass of gadolinium (1.20 kg), shaped as packed bed spheres, is housed in 8 regenerators. A magnetic system, based on a double U configuration of permanent magnets, provides a magnetic flux density of 1.25 T with an air gap of 43 mm. A rotary vane pump forces the regenerating fluid through the regenerators. The operational principle of the magnetic refrigerator and initial experimental results are reported and analyzed.

  11. Effect of {gamma}-ray irradiation on the magnetic properties of NdFeB and Fe-Cr-Co permanent magnets

    Energy Technology Data Exchange (ETDEWEB)

    Gao, R.S. [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Zhen, L. [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China)]. E-mail: zhenl@hit.edu.cn; Li, G.A. [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Xu, C.Y. [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Shao, W.Z. [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China)

    2006-07-15

    The effect of {gamma}-ray irradiation on the magnetic properties of NdFeB and Fe-Cr-Co permanent magnets has been investigated. The magnetic flux loss of two kinds of magnets before and after irradiation was measured. Results show that the effect of {gamma}-ray irradiation on the magnetic properties of sintered NdFeB is not so obvious as that on Fe-Cr-Co magnet. Irradiation-induced damage from {gamma}-ray for the Fe-Cr-Co magnets was characterized for the first time. The decline of permanent magnetic properties of Fe-Cr-Co magnet induced by {gamma}-ray irradiation is reversible except for the maximum energy product (BH){sub max}. The difference of coercivity mechanism between these two kinds of permanent magnets is responsible for the different dependence of magnetic properties loss induced by {gamma}-ray irradiation.

  12. Improved magnetic properties and thermal stabilities of Pr-Nd-Fe-B sintered magnets by Hf addition

    Science.gov (United States)

    Jiang, Qingzheng; Lei, Weikai; Zeng, Qingwen; Quan, Qichen; Zhang, Lili; Liu, Renhui; Hu, Xianjun; He, Lunke; Qi, Zhiqi; Ju, Zhihua; Zhong, Minglong; Ma, Shengcan; Zhong, Zhenchen

    2018-05-01

    Nd2Fe14B-type permanent magnets have been widely applied in various fields such as wind power, voice coil motors, and medical instruments. The large temperature dependence of coercivity, however, limits their further applications. We have systematically investigated the magnetic properties, thermal stabilities and coercivity mechanisms of the (Pr0.2Nd0.8)13Fe81-xB6Hfx (x=0, 0.5) nanocrystalline magnets fabricated by a spark plasma sintering (SPS) technique. The results indicate that the influence of Hf addition is significant on magnetic properties and thermal stabilities of the (PrNd)2Fe14B-type sintered magnets. It is shown that the sample with x = 0.5 at 300 K has much higher coercivity and remanent magnetization than those counterparts without Hf. The temperature coefficients of remanence (α) and coercivity (β) of the (Pr0.2Nd0.8)13Fe81-xB6Hfx magnets are improved significantly from -0.23 %/K, -0.57 %/K for the sample at x = 0 to -0.17 %/K, -0.49 %/K for the sample at x = 0.5 in the temperature range of 300-400 K. Furthermore, it is found out that the domain wall pinning mechanism is more likely responsible for enhancing the coercivity of the (Pr0.2Nd0.8)13Fe81-xB6Hfx magnets.

  13. Three-dimensional quadrupole lenses made with permanent magnets

    International Nuclear Information System (INIS)

    Ivanov, A.S.

    1984-01-01

    The performance of accelerator systems with quadrupole magnets can be improved by using permanent magnets in quadrupole lenses. This requires better methods for treating the three-dimensional nature of the magnetic fields and the nonlinear characteristics of the magnets. A numerical method is described for simulating three-dimensional magnetic fields and used to analyze quadrupole lenses and doublets with permanent magnets. The results, which are confirmed experimentally, indicate that both the quadrupole magnetic gradient and the effective field length are changed in permanent-magnet quadrupole lenses when the pole lengths and the gap between the lenses are varied while the other characteristics of the magnets remain unchanged

  14. Developments in the processing and properties of NdFeb-type permanent magnets

    International Nuclear Information System (INIS)

    Brown, David; Ma, B.-M.; Chen Zhongmin

    2002-01-01

    The composition, microstructure and processing of NdFeB-type permanent magnets are all critical factors for the successful production of high performance magnet components. Three common fabrication routes can be used to categorize these NdFeB-based bulk magnets: sintering, polymer bonding and hot deformation. Generally, the former type of magnet has a high-energy product (30-50 MGOe), full density and a relatively simple shape. Bonded magnets have intermediate energy products (10-18 MGOe), lower density and can be formed into intricate net-shapes. Hot deformed magnets possess full density, intermediate to high-energy products (15-46 MGOe), isotropic or anisotropic properties and have the potential to be formed into net shapes. This article discusses the critical issues of improved magnetic performance, environmental stability, net-shape formability and magnetization behavior for the main categories of NdFeB magnets

  15. Design of permanent magnetic solenoids for REGAE

    Energy Technology Data Exchange (ETDEWEB)

    Gehrke, Tim

    2013-10-15

    The Relativistic Electron Gun for Atomic Exploration (REGAE) is a small linear accelerator at DESY in Hamburg, which produces short, low emittance electron bunches. It is originally designed and built for ultrafast electron diffraction (UED) within the framework of the Center for Free-Electron Laser Science (CFEL). Additionally, two future experiments are planned at REGAE. First, an external injection experiment for Laser Wakefield Acceleration (LWA) will be performed in the framework of the LAOLA collaboration (LAboratory fOr Laser- and beam-driven plasma Acceleration). This experiment will provide a method for the reconstruction of the electric field distribution within a linear plasma wakefield. Second, a time resolving high energy Transmission Electron Microscope (TEM) will be implemented. Among others it is designed to allow for living cell imaging. Both experiments require strong focusing magnets inside the new target chamber at REGAE. Permanent magnetic solenoids (PMSs) can provide the needed focusing strength due to their enormous surface current density, while having compact dimensions at the same time. The present thesis deals with the design of such strong focusing PMSs. Since short and strong solenoids, as required for REGAE, exhibit a distinct non-linearity, the induced emittance growth is relatively large. This emittance growth is investigated and minimized for different set-ups with axially and radially magnetized annular magnets. Furthermore a magnetic shielding is developed. Together with a mechanical lifting system it assures that magnetic leakage fields do not disturb experiments, where the PMSs are removed from the beamline.

  16. Design of permanent magnetic solenoids for REGAE

    International Nuclear Information System (INIS)

    Gehrke, Tim

    2013-10-01

    The Relativistic Electron Gun for Atomic Exploration (REGAE) is a small linear accelerator at DESY in Hamburg, which produces short, low emittance electron bunches. It is originally designed and built for ultrafast electron diffraction (UED) within the framework of the Center for Free-Electron Laser Science (CFEL). Additionally, two future experiments are planned at REGAE. First, an external injection experiment for Laser Wakefield Acceleration (LWA) will be performed in the framework of the LAOLA collaboration (LAboratory fOr Laser- and beam-driven plasma Acceleration). This experiment will provide a method for the reconstruction of the electric field distribution within a linear plasma wakefield. Second, a time resolving high energy Transmission Electron Microscope (TEM) will be implemented. Among others it is designed to allow for living cell imaging. Both experiments require strong focusing magnets inside the new target chamber at REGAE. Permanent magnetic solenoids (PMSs) can provide the needed focusing strength due to their enormous surface current density, while having compact dimensions at the same time. The present thesis deals with the design of such strong focusing PMSs. Since short and strong solenoids, as required for REGAE, exhibit a distinct non-linearity, the induced emittance growth is relatively large. This emittance growth is investigated and minimized for different set-ups with axially and radially magnetized annular magnets. Furthermore a magnetic shielding is developed. Together with a mechanical lifting system it assures that magnetic leakage fields do not disturb experiments, where the PMSs are removed from the beamline.

  17. Magnetic resonance elastometry using a single-sided permanent magnet

    International Nuclear Information System (INIS)

    Tan, Carl S; Marble, Andrew E; Ono, Yuu

    2012-01-01

    In this paper, we describe a magnetic resonance method of measuring material elasticity using a single-sided magnet with a permanent static field gradient. This method encodes sample velocity in a reciprocal space using Hahn spin-echoes with variable timing. The experimental results show a strong correlation between magnetic resonance signal attenuation and elasticity when an oscillating force is applied on the sample. This relationship in turn provides us with information about the displacement velocity experienced by the sample, which is inversely proportional to Young's modulus. The proposed method shows promise in offering a portable and cost-effective magnetic resonance elastography system. (paper)

  18. Planar permanent magnet multipoles: Measurements and configurations

    International Nuclear Information System (INIS)

    Cremer, T.; Tatchyn, R.

    1995-05-01

    Biplanar arrays of N rectangular permanent magnet (PM) blocks can be used to generate high quality N-pole fields in close proximity to the array axis. In applications featuring small-diameter charged particle beams, N-poles of adequate quality can be realized at relatively low cost using small volumes of PM material. In this paper we report on recent measurements performed on planar PM multipoles, and discuss techniques for improving the field quality of such devices at distances appreciably far away from the axis. Applications to hybrid/PM insertion device designs for linac-driven Free Electron Laser (FEL) operation in the x-ray range are described

  19. Comparison of torque capability of three-phase permanent magnet synchronous motors with different permanent magnet arrangement

    International Nuclear Information System (INIS)

    Stumberger, Bojan; Stumberger, Gorazd; Hadziselimovic, Miralem; Hamler, Anton; Gorican, Viktor; Jesenik, Marko; Trlep, Mladen

    2007-01-01

    The paper presents a comparison of torque capability of three-phase permanent magnet synchronous motors with different permanent magnet arrangement. Motors with the following permanent magnet topologies were accounted for in the comparison: the surface-mounted permanent magnet synchronous motor (SMPMSM), the interior permanent magnet synchronous motor (IPMSM), the permanent magnet-assisted synchronous reluctance motor (PMASRM) and the flux reversal permanent magnet motor (FRPMM). Finite element method analysis is employed to determine the performance of each motor. Calculated performance of four-pole IPMSM determined by finite element method calculation is confirmed with the measurements at nearly constant nominal output power in the range of speed 3000-10,000 rpm

  20. Design of permanent magnet synchronous motor within minimum cost

    OpenAIRE

    Півняк, Геннадій Григорович; Бешта, Олександр Степанович; Фурса, Сергій Григорійович; Neuberger, Nikolaus; Nolle, N.

    2010-01-01

    The article describes design and simulation experience of permanent magnet synchronous motor (PMSM). The design goal is to develop PMSM of the least possible cost. For that purpose the standard induction motor stator was applied as a basic solution and permanent magnets were installed in rotor. Simulation results are presented, the dependence of efficiency and total loss on magnet material mass are obtained. The optimal value of permanent magnets is estimated for the given electric motor frame.

  1. sizing of wind powered axial flux permanent magnet alternator using

    African Journals Online (AJOL)

    user

    2016-10-04

    Oct 4, 2016 ... Keywords: Wind-Power, Axial flux, Axial Flux Permanent Machines (AFPM), Axial Flux Permanent Magnet ... energy for power generation, a high constraint is the .... arrangements as Single-Rotor Single-Stator Structure.

  2. Introduction to the permanent magnet motor market

    Energy Technology Data Exchange (ETDEWEB)

    Sawa, Toshihiro; Hamada, Kaneyuki [Yaskawa Electric Corp. (Japan)

    2000-07-01

    According to the Kyoto summit on global warming (COP3) in December 1997, the green-house gas emission level has to be reduced to 92-94% of the 1990 green-house gas level by the year 2014-2018. This would require conserving energy. An efficient means of achieving this voluntary goal is by employing high-efficiency drives, since motors consume 70% of all electricity for industrial use in Japan. As adjustable speed drives become popular, interior permanent magnet (IPM) motors, lately, have been recognized for high-efficiency performance. Due to the progress in permanent magnet technology combined with modern control methods, especially vector control with and without speed-sensors, the IPM motor is gaining in popularity. Compact size and high-efficiency performance is furthering the IPM motor as the preferred motor in many applications. This paper describes the principle and operation of IPM motors and compares its performance with that of an induction motor. Important features and practical control methods for IPM motors are presented. Various application examples highlighting the advantages of employing an IPM motor system are discussed. The applications include, but are not limited to, machine tools, fans, pumps, elevators, cranes, etc. (orig.)

  3. In-situ magnetization of NdFeB magnets for permanent magnet machines

    International Nuclear Information System (INIS)

    Chang, L.; Eastham, T.R.; Dawson, G.E.

    1991-01-01

    In-situ magnetizers are needed to facilitate the assembly of permanent magnet machines and to remagnetize the magnets after weakening due to a fault condition. The air-core magnetizer in association with the silicon steel lamination structure of the rotor has advantages over its iron-core counterpart. This novel method has been used to magnetize the NdFeB magnets in a 30-hp permanent magnet synchronous motor. The magnetizing capability for different magnetizer geometries was investigated for the magnetization of NdFeB material. The design, testing, and operation of this magnetizer are reported in this paper

  4. Magnetically nonlinear dynamic model of synchronous motor with permanent magnets

    International Nuclear Information System (INIS)

    Hadziselimovic, Miralem; Stumberger, Gorazd; Stumberger, Bojan; Zagradisnik, Ivan

    2007-01-01

    This paper deals with a magnetically nonlinear two-axis dynamic model of a permanent magnet synchronous motor (PMSM). The geometrical and material properties of iron core and permanent magnets, the effects of winding distribution, saturation, cross-saturation and slotting effects are, for the first time, simultaneously accounted for in a single two-axis dynamic model of a three-phase PMSM. They are accounted for by current- and position-dependent characteristics of flux linkages. These characteristics can be determined either experimentally or by the finite element (FE) computations. The results obtained by the proposed dynamic model show a very good agreement with the measured ones and those obtained by the FE computation

  5. Magnetic Performance of a Nanocomposite Permanent Material

    International Nuclear Information System (INIS)

    Liu Min; Han Guang-Bing; Gao Ru-Wei

    2011-01-01

    We build a sandwiched structure model in which the intergranular phase (IP) is homogeneously distributed between soft and hard magnetic grains, and gives a continuously anisotropic expression of the coupling part under the assumption that the IP weakens the intergrain exchange-coupling interaction. Based on the idea that the hardening mechanism is of the pinning type, we calculate the effect of the IP's thickness d and its anisotropy constant K 1 (0) on the intrinsic coercivity of a nanocomposite permanent material. The calculated results indicate that the domain wall goes twice through irreversible domain wall displacement during the process of moving from soft to hard magnetic grains, and the intrinsic coercivity increases with increasing d, but decreases with increasing K 1 (0). When d and K 1 (0) take 2 nm and 0.7K h , respectively, with K h being the anisotropy constant in the inner part of the hard magnetic grain, the calculated intrinsic coercivity is in good agreement with the experimental data. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  6. Some economic aspects of rare-earth permanent magnets

    International Nuclear Information System (INIS)

    Zijlstra, H.

    1978-01-01

    The commercial feasibility of RE permanent magnets is analyzed in terms of price per unit of magnetostatic energy. The availability of the raw materials is also taken into consideration. The conclusion is that RE magnets are and remain relatively expensive as compared with other permanent magnets, and will find only limited application. (author)

  7. Modeling demagnetization effects in permanent magnet synchronous machines

    NARCIS (Netherlands)

    Kral, C.; Sprangers, R.L.J.; Waarma, J.; Haumer, A.; Winter, O.; Lomonova, E.

    2010-01-01

    This paper presents a permanent magnet model which takes temperature dependencies and demagnetization effects into account. The proposed model is integrated into a magnetic fundamental wave machine model using the model- ing language Modelica. For different rotor types permanent magnet models are

  8. Multiple recycling of NdFeB-type sintered magnets

    Energy Technology Data Exchange (ETDEWEB)

    Zakotnik, M. [Department of Metallurgy and Materials, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom)], E-mail: miha.zakotnik@gmail.com; Harris, I.R.; Williams, A.J. [Department of Metallurgy and Materials, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom)

    2009-02-05

    Some fully dense, sintered NdFeB-type magnets (employed in VCM disc drives) have been subjected to a recycling process using the hydrogen decrepitation (HD) process. After a brief milling treatment, the powder was aligned, pressed and re-sintered and this procedure was repeated four times with a progressive fall in the density and in the magnetic properties. The chemical analysis indicated that this was due to the progressive oxidation of the Nd-rich material and to some Nd loss by evaporation. The procedure was then repeated but with the addition (blending) of a fine powder of neodymium hydride after the first cycle. It was found that the addition of 1 at.% of neodymium at each stage was sufficient to maintain the density and the magnetic properties of the recycled magnets up to and including the 4th cycle. Inductively coupled plasma (ICP) and metallographic analysis indicated that the neodymium hydride additions compensated for the neodymium loss due to evaporation and to oxidation so that the proportion of Nd-rich material remained approximately constant. The additional amount of Nd{sub 2}O{sub 3} in the blended recycled magnets appeared to inhibit grain growth on the 3rd and 4th cycles when compared to that of the unblended magnets. The next challenge is to see if the process can be scaled-up to an industrial scale.

  9. The dynamic behavior of magnetic fluid adsorbed to small permanent magnet in alternating magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Sudo, Seiichi, E-mail: sudo@akita-pu.ac.j [Faculty of Systems Science and Technology, Akita Prefectural University, Ebinokuchi 84-4, Yurihonjo 015-0055 (Japan); Asano, Daisaku [Faculty of Systems Science and Technology, Akita Prefectural University, Ebinokuchi 84-4, Yurihonjo 015-0055 (Japan); Takana, Hidemasa; Nishiyama, Hideya [Institute of Fluid Science, Tohoku University, Katahira 2-1-1, Aobaku, Sendai 980-8577 (Japan)

    2011-05-15

    The dynamic behavior of a magnetic fluid adsorbed to a small NdFeB permanent magnet subjected to an alternating magnetic field was studied with a high speed video camera system. The directions of alternating magnetic field are parallel and opposite to that of the permanent magnet. It was found that the surface of magnetic fluid responds to the external alternating magnetic field in elongation and contraction with a lot of spikes. Generation of a capillary magnetic fluid jet was observed in the neighbourhood of a specific frequency of alternating field. The effect of gravitational force on surface phenomena of magnetic fluid adsorbed to the permanent magnet was revealed. - Research Highlights: Magnetic fluid of the system responds to alternating magnetic field with higher frequencies. Large-amplitude surface motions of magnetic fluid occur at the specific frequencies of the external field. Capillary jets of magnetic fluid are generated at the natural frequency of the system.

  10. Hard magnetic property and δM(H) plot for sintered NdFeB magnet

    International Nuclear Information System (INIS)

    Gao, R.W.; Zhang, D.H.; Li, W.; Li, X.M.; Zhang, J.C.

    2000-01-01

    The hard magnetic properties and the interactions between the grains for sintered Nd 16 Fe 73 Co 5 B 6 magnets are investigated by using δM(H) plot technique. The results show that the δM(H) plot of NdFeB sintered magnet can explain the effects of the microstructure (size, shape and orientation of the grains) and the intergrain interactions on the hard magnetic properties of the magnet. However, the value of δM(H) is positive when the applied field is not strong enough, which means that the common δM(H) plot theory is not completely consistent with the sintered NdFeB magnet

  11. Adjustable permanent magnet assembly for NMR and MRI

    Science.gov (United States)

    Pines, Alexander; Paulsen, Jeffrey; Bouchard, Louis S; Blumich, Bernhard

    2013-10-29

    System and methods for designing and using single-sided magnet assemblies for magnetic resonance imaging (MRI) are disclosed. The single-sided magnet assemblies can include an array of permanent magnets disposed at selected positions. At least one of the permanent magnets can be configured to rotate about an axis of rotation in the range of at least +/-10 degrees and can include a magnetization having a vector component perpendicular to the axis of rotation. The single-sided magnet assemblies can further include a magnet frame that is configured to hold the permanent magnets in place while allowing the at least one of the permanent magnets to rotate about the axis of rotation.

  12. Advanced optimization of permanent magnet wigglers using a genetic algorithm

    Energy Technology Data Exchange (ETDEWEB)

    Hajima, Ryoichi [Univ. of Tokyo (Japan)

    1995-12-31

    In permanent magnet wigglers, magnetic imperfection of each magnet piece causes field error. This field error can be reduced or compensated by sorting magnet pieces in proper order. We showed a genetic algorithm has good property for this sorting scheme. In this paper, this optimization scheme is applied to the case of permanent magnets which have errors in the direction of field. The result shows the genetic algorithm is superior to other algorithms.

  13. Advanced optimization of permanent magnet wigglers using a genetic algorithm

    International Nuclear Information System (INIS)

    Hajima, Ryoichi

    1995-01-01

    In permanent magnet wigglers, magnetic imperfection of each magnet piece causes field error. This field error can be reduced or compensated by sorting magnet pieces in proper order. We showed a genetic algorithm has good property for this sorting scheme. In this paper, this optimization scheme is applied to the case of permanent magnets which have errors in the direction of field. The result shows the genetic algorithm is superior to other algorithms

  14. Magnetostatic interactions and forces between cylindrical permanent magnets

    International Nuclear Information System (INIS)

    Vokoun, David; Beleggia, Marco; Heller, Ludek; Sittner, Petr

    2009-01-01

    Permanent magnets of various shapes are often utilized in magnetic actuators, sensors or releasable magnetic fasteners. Knowledge of the magnetic force is required to control devices reliably. Here, we introduce an analytical expression for calculating the attraction force between two cylindrical permanent magnets on the assumption of uniform magnetization. Although the assumption is not fulfilled exactly in cylindrical magnets, we obtain a very good agreement between the calculated and measured forces between two identical cylindrical magnets and within an array of NdFeB cylindrical magnets.

  15. Control of permanent magnet synchronous motors

    CERN Document Server

    Vaez-Zadeh, Sadegh

    2018-01-01

    This is the first comprehensive, coherent, and up-to-date book devoted solely to the control of permanent magnet synchronous (PMS) motors, as the fastest growing AC motor. It covers a deep and detailed presentation of major PMS motor modeling and control methods. The readers can find rich materials on the fundamentals of PMS motor control in addition to new motor control methods, which have mainly been developed in the last two decades, including recent advancements in the field in a systematic manner. These include extensive modeling of PMS motors and a full range of vector control and direct torque control schemes, in addition to predictive control, deadbeat control, and combined control methods. All major sensorless control and parameter estimation methods are also studied. The book covers about 10 machine models in various reference frames and 70 control and estimation schemes with sufficient analytical and implementation details including about 200 original figures. A great emphasis is placed on energy-s...

  16. Distributed generation induction and permanent magnet generators

    CERN Document Server

    Lai, L

    2007-01-01

    Distributed power generation is a technology that could help to enable efficient, renewable energy production both in the developed and developing world. It includes all use of small electric power generators, whether located on the utility system, at the site of a utility customer, or at an isolated site not connected to the power grid. Induction generators (IGs) are the cheapest and most commonly used technology, compatible with renewable energy resources. Permanent magnet (PM) generators have traditionally been avoided due to high fabrication costs; however, compared with IGs they are more reliable and productive. Distributed Generation thoroughly examines the principles, possibilities and limitations of creating energy with both IGs and PM generators. It takes an electrical engineering approach in the analysis and testing of these generators, and includes diagrams and extensive case study examples o better demonstrate how the integration of energy sources can be accomplished. The book also provides the ...

  17. Magnetic losses versus sintering treatment in Mn-Zn ferrites

    Energy Technology Data Exchange (ETDEWEB)

    Beatrice, Cinzia, E-mail: c.beatrice@inrim.it [Istituto Nazionale di Ricerca Metrologica, Nanoscience and Materials Division, Torino (Italy); Tsakaloudi, Vasiliki [Laboratory of Inorganic Materials, CERTH, Thermi-Thessaloniki (Greece); Dobák, Samuel [Institute of Physics, P.J. Šafárik University, Košice (Slovakia); Zaspalis, Vassilios [Department of Chemical Engineering Aristotle University of Thessaloniki, Thessaloniki (Greece); Fiorillo, Fausto [Istituto Nazionale di Ricerca Metrologica, Nanoscience and Materials Division, Torino (Italy)

    2017-05-01

    Mn-Zn ferrites prepared by different sintering schedules at 1325 °C, 1340 °C, and 1360 °C, have been characterized from the structural, electrical, and magnetic viewpoint. Magnetic losses and complex permeability have been, in particular, measured and analyzed from quasi-static excitation up to 1 GHz. It is observed that lower sintering temperatures and shorter treatment times lead to more homogeneous grain structure and better soft magnetic response at all frequencies. It is shown, however, that, once the contribution by eddy currents is singled out, the energy losses tend to coincide beyond a few MHz in the differently treated samples. The interpretative approach consists in separating the contributions by the domain wall displacements and the magnetization rotations to complex permeability and losses as a function of frequency. This can be accomplished in a relatively simple way in the low induction region described by the Rayleigh law, where these quantities can be quantitatively related and the linear Landau-Lifshitz-Gilbert equation applies, account being taken of the distribution in amplitude and orientation of the local anisotropy fields. - Highlights: • DC-1 GHz magnetic losses and complex permeability of Mn-Zn ferrites are analyzed. • Contributions by domain wall displacements and rotations are separately obtained. • Energy losses caused by eddy currents and spin damping are separately identified. • Microstructure is shown to chiefly affect the domain wall processes. • Rotational permeability and loss are predicted through Landau-Lifshitz equation.

  18. Structure and magnetic field of periodic permanent magnetic focusing system with open magnetic rings

    International Nuclear Information System (INIS)

    Peng Long; Li Lezhong; Yang Dingyu; Zhu Xinghua; Li Yuanxun

    2011-01-01

    The magnetic field along the central axis for an axially magnetized permanent magnetic ring was investigated by analytical and finite element methods. For open magnetic rings, both calculated and measured results show that the existence of the radial magnetic field creates a remarkable cosine distribution field along the central axis. A new structure of periodic permanent magnet focusing system with open magnetic rings is proposed. The structure provides a satisfactory magnetic field with a stable peak value of 120 mT for a traveling wave tube system. - Research highlights: → For open magnetic rings, both calculated and measured results show that the existence of the radial magnetic field creates a remarkable cosine distribution field along the central axis. → A new structure of periodic permanent magnet (PPM) focusing system with open magnetic rings is proposed. → The new PPM focusing system with open magnetic rings meets the requirements for TWT system.

  19. Rotor for a line start permanent magnet machine

    Science.gov (United States)

    Melfi, Mike; Schiferl, Rich; Umans, Stephen

    2017-07-11

    A rotor comprises laminations with a plurality of rotor bar slots with an asymmetric arrangement about the rotor. The laminations also have magnet slots equiangularly spaced about the rotor. The magnet slots extend near to the rotor outer diameter and have permanent magnets disposed in the magnet slots creating magnetic poles. The magnet slots may be formed longer than the permanent magnets disposed in the magnets slots and define one or more magnet slot apertures. The permanent magnets define a number of poles and a pole pitch. The rotor bar slots are spaced from adjacent magnet slots by a distance that is at least 4% of the pole pitch. Conductive material is disposed in the rotor bar slots, and in some embodiments, may be disposed in the magnet slot apertures.

  20. Permanent magnet system to guide superparamagnetic particles

    Science.gov (United States)

    Baun, Olga; Blümler, Peter

    2017-10-01

    A new concept of using permanent magnet systems for guiding superparamagnetic nano-particles on arbitrary trajectories over a large volume is proposed. The basic idea is to use one magnet system which provides a strong, homogeneous, dipolar magnetic field to magnetize and orient the particles, and a second constantly graded, quadrupolar field, superimposed on the first, to generate a force on the oriented particles. In this configuration the motion of the particles is driven predominantly by the component of the gradient field which is parallel to the direction of the homogeneous field. As a result, particles are guided with constant force and in a single direction over the entire volume. The direction is simply adjusted by varying the angle between quadrupole and dipole. Since a single gradient is impossible due to Gauß' law, the other gradient component of the quadrupole determines the angular deviation of the force. However, the latter can be neglected if the homogeneous field is stronger than the local contribution of the quadrupole field. A possible realization of this idea is a coaxial arrangement of two Halbach cylinders. A dipole to evenly magnetize and orient the particles, and a quadrupole to generate the force. The local force was calculated analytically for this particular geometry and the directional limits were analyzed and discussed. A simple prototype was constructed to demonstrate the principle in two dimensions on several nano-particles of different size, which were moved along a rough square by manual adjustment of the force angle. The observed velocities of superparamagnetic particles in this prototype were always several orders of magnitude higher than the theoretically expected value. This discrepancy is attributed to the observed formation of long particle chains as a result of their polarization by the homogeneous field. The magnetic moment of such a chain is then the combination of that of its constituents, while its hydrodynamic radius

  1. Relations microstructure - magnetic properties - squareness factor of PrFeB and NdFeB sintered magnets prepared with hydrogen

    International Nuclear Information System (INIS)

    Perigo, Elio Alberto

    2009-01-01

    In this work, it has firstly been evaluated the preparation of Pr 16 Fe 76 B 8 sintered permanent magnets (% at.) by means of high-energy milling using a planetary ball mill. The influence of both milling speed and time has been verified. The best magnetic properties [J R = (1.02 ± 0.02) T, μ 0J H c = (1.42 ± 0.03) T and (BH) max = (200 ± 4) kJm -3 ] have been found for a permanent magnet prepared with the magnetic alloy milled during 75 minutes using a rotational milling speed of 200 rpm. In order to improve the remanence, the hydrogen decrepitation process time has been reduced from 60 minutes to 2 minutes. In this case, it has been obtained a sintered magnet with J R = (1.14 ± 0.02) T, μ 0J H c = (1.44 ± 0.03) T and (BH) max = (250 ± 5) kJm -3 due to the improvement of crystallographic alignment of the hard magnetic phase. During such investigation, a new methodology to quantify the parameter has been developed. Subsequently, for the first time, a quantitative correlation between the microstructure and the squareness factor in anisotropic sintered RE 16 Fe 76 B 8 (RE = Nd or Pr) magnets has been proposed. The presented expression utilizes the mean size, the mean elongation and the mean roundness of the hard magnetic grains as well as their respective standard deviations. The squareness factor can be improved with a microstructure with rounder grains and with a sharp grain size distribution. The grain size homogeneity is more important to enhance the squareness factor compared to grain shape homogeneity. Furthermore, it has also been verified that the annealing after sintering improves the grain shape homogeneity and the milling enhances the grain size homogeneity. Moreover, the effect of the temperature on the squareness factor of anisotropic sintered magnets has also been evaluated. Such parameter is mainly controlled by the sample's microstructure, in agreement with the proposed expression. Furthermore, a quantitative correlation between the maximum

  2. Preparation of Nd–Fe–B sintered magnets from HDDR-processed powder

    Energy Technology Data Exchange (ETDEWEB)

    Takagi, Kenta, E-mail: k-takagi@aist.go.jp [Green Innovative Magnetic Materials Research Center, National Institute of Advanced Industrial Science and Technology (AIST), Nagoya 463-8560 (Japan); Akada, Misaho [Magnetic Materials R& D Center, Research Associations of Magnetic Materials for High-Efficiency Motors (MagHEM), Nagoya 463-8560 (Japan); Soda, Rikio; Ozaki, Kimihiro [Green Innovative Magnetic Materials Research Center, National Institute of Advanced Industrial Science and Technology (AIST), Nagoya 463-8560 (Japan)

    2015-11-01

    The electric-current sintering technique was used to fully densify hydrogenation–disproportionation–desorption–recombination (HDDR)-processed Nd–Fe–B powder at temperatures below the grain growth temperature in order to produce high-coercive bulk magnets. However, the sintered magnets exhibited anomalous coercivity reduction that depended on sintered density. Reheating examination of the sintered magnets revealed that the reduced coercivity was increased in proportion to the heating temperature, resulting in complete recovery of coercivity. As a result, the combination of electric-current sintering and post-annealing produced sintered magnets with a coercivity of 15 kOe. Scanning and transmission electron microscopy revealed no evidence that associated the anomalous coercivity reduction and recovery with grain boundary morphology. On the other hand, various HDDR powders with different particle sizes were sintered, and finer powders yielded lower coercivity after sintering, implying that the anomalous coercivity reduction was associated with particle surface oxides of the raw powder. - Highlights: • We conduct a sintering of HDDR-processed Nd–Fe–B powder without coercivity reduction. • Rapid current sintering allows densification of this powder without grain growth. • However, the sintered magnets show an anomalous coercivity reduction phenomenon. • It is found that post-annealing completely recovers the reduced coercivity. • The anomalous coercivity reduction would be due to surface oxide of the raw powder.

  3. Magnetic viscosity and coercivity mechanisms in sintered and melt spun NdFeB

    International Nuclear Information System (INIS)

    Street, R.; Bingham, D.; Day, R.K.; Dunlop, J.B.

    1988-01-01

    Magnetic viscosity parameters kT/q(=Sv) of sintered and melt spun NdFeB vary with internal field. During initial magnetization of thermally demagnetized specimens signifiant viscosity occurs with melt spun NdFeB but is negligible with sintered NdFeB. Differences in mechanisms of magnetization account for this behaviour

  4. Permanent magnet quadrupoles for the CLIC Drive Beam decelerator

    CERN Document Server

    Shepherd, Ben; Collomb, Norbert

    2012-01-01

    STFC in collaboration with CERN has developed a new type of adjustable permanent magnet based quadrupole for the CLIC Drive Beam Decelerator. It uses vertical movement of the permanent magnets to achieve an integrated gradient range of 3.6-14.6T, which will allow it to be used for the first 60% of the decelerator line. Construction of a prototype of this magnet has begun; following this, it will be measured magnetically at CERN and Daresbury Laboratory.

  5. Modeling of ironless permanent magnet planar motor structures

    NARCIS (Netherlands)

    Boeij, de J.; Lomonova, E.A.; Vandenput, A.J.A.

    2006-01-01

    This paper describes an analytical model that includes end effects for ironless synchronous permanent-magnet planar actuators. Because of its flexibility, the model can be used to predict the performance of various permanent-magnet array and coil array topologies and commutation schemes. Moreover,

  6. Method and apparatus for assembling a permanent magnet pole assembly

    Science.gov (United States)

    Carl, Jr., Ralph James; Bagepalli, Bharat Sampathkumaran [Niskayuna, NY; Jansen, Patrick Lee [Scotia, NY; Dawson, Richard Nils [Voorheesville, NY; Qu, Ronghai [Clifton Park, NY; Avanesov, Mikhail Avramovich [Moscow, RU

    2009-08-11

    A pole assembly for a rotor, the pole assembly includes a permanent magnet pole including at least one permanent magnet block, a plurality of laminations including a pole cap mechanically coupled to the pole, and a plurality of laminations including a base plate mechanically coupled to the pole.

  7. Sensorless V/f Control of Permanent Magnet Synchronous Motors

    OpenAIRE

    Montesinos-Miracle, Daniel; Perera, P. D. Chandana; Galceran-Arellano, Samuel; Blaabjerg, Frede

    2010-01-01

    V/f control strategy for permanent magnet synchronous motors can be useful for HVAC applications, where not high performance is required. Permanent magnet synchronous motors have efficiency advantages over the induction motor. But open loop V/f control is not stable in the whole frequency range. As demonstrated, the V/f control strategy becomes

  8. Isotropic and anisotropic nanocrystalline NdFeB-based magnets prepared by spark plasma sintering and hot deformation

    International Nuclear Information System (INIS)

    Liu, Z.W.; Huang, Y.L.; Huang, H.Y.; Zhong, X.C.; Yu, Y.H.; Zeng, D.C.

    2011-01-01

    Isotropic and anisotropic NdFeB permanent magnets were prepared by Spark Plasma Sintering (SPS) and SPS followed hot deformation (HD), respectively, using melt spun NdFeB ribbons with various compositions as starting materials. It is found that, based on RE-rich composition, SPSed magnets sintered at low temperatures (<700 C) almost maintained the uniform fine grain structure inherited from rapid quenching. At higher temperatures, a distinct two-zone (coarse grain and fine grain zones) structure was formed in the SPSed magnets. The SPS temperature and pressure have important effects on the grain structure, which led to the variations in the magnetic properties. By employing low SPS temperature and high pressure, high-density magnets with negligible coarse grain zone and an excellent combination of magnetic properties can be obtained. For single phase NdFeB alloy, because of the deficiency of Nd-rich phases, it is relatively difficult to consolidate micro-sized melt spun powders into high density bulk magnet, but generally a larger particle size is beneficial to achieve better magnetic properties. Anisotropic magnets with a maximum energy product of approx. equal to 38 MGOe were produced by the SPS+HD process. HD did not lead to obvious grain growth and the two-zone structure still existed in the hot deformed magnets. The results indicated that nanocrystalline NdFeB magnets without significant grain growth and with excellent properties could be obtained by SPS and HD processes. (author)

  9. Open H-shaped permanent magnet structure for NMR imaging

    International Nuclear Information System (INIS)

    Nguyen, V.; Delamare, J.; Yonnet, J.P.

    1996-01-01

    Since NMR imaging at low field is now technically possible, permanent magnets can replace resistive coils or superconducting magnets. This paper reviews most of NMR structures that provide an uniform field using only permanent magnets. We propose a new open H-shaped structure that is simple to manufacture. This structure has been calculated thanks to an optimization program and a calculation method we presente here. It enables to determine with a good accuracy the field created by passive systems composed by permanent magnets and ferromagnetic materials. (author)

  10. Globally Optimal Segmentation of Permanent-Magnet Systems

    DEFF Research Database (Denmark)

    Insinga, Andrea Roberto; Bjørk, Rasmus; Smith, Anders

    2016-01-01

    Permanent-magnet systems are widely used for generation of magnetic fields with specific properties. The reciprocity theorem, an energy-equivalence principle in magnetostatics, can be employed to calculate the optimal remanent flux density of the permanent-magnet system, given any objective...... remains unsolved. We show that the problem of optimal segmentation of a two-dimensional permanent-magnet assembly with respect to a linear objective functional can be reduced to the problem of piecewise linear approximation of a plane curve by perimeter maximization. Once the problem has been cast...

  11. Application of permanent magnets in accelerators and electron storage rings

    International Nuclear Information System (INIS)

    Halbach, K.

    1984-09-01

    After an explanation of the general circumstances in which the use of permanent magnets in accelerators is desirable, a number of specific magnets will be discussed. That discussion includes magnets needed for the operation of accelerators as well as magnets that are employed for the utilization of charged particle beams, such as the production of synchrotron radiation. 15 references, 8 figures

  12. Permanent magnets in accelerators can save energy, space and cost

    DEFF Research Database (Denmark)

    Bødker, F.; Baandrup, L.O.; Hauge, N.

    2013-01-01

    coils permit fine tuning of the magnetic field. Magnetic field measurements and thermal stability tests show that the Green Magnet fully meets the magnetic requirements of the previously used electromagnet. A permanent 30° bending dipole is currently being development to demonstrate the use of Green...

  13. Dovetail Rotor Construction For Permanent-Magnet Motors

    Science.gov (United States)

    Kintz, Lawrence J., Jr.; Puskas, William J.

    1988-01-01

    New way of mounting magnets in permanent-magnet, electronically commutated, brushless dc motors. Magnets wedge shaped, tapering toward center of rotor. Oppositely tapered pole pieces, electron-beam welded to rotor hub, retain magnets against centrifugal force generated by spinning rotor. To avoid excessively long electron-beam welds, pole pieces assembled in segments rather than single long bars.

  14. A Novel Permanent Magnetic Angular Acceleration Sensor

    Directory of Open Access Journals (Sweden)

    Hao Zhao

    2015-07-01

    Full Text Available Angular acceleration is an important parameter for status monitoring and fault diagnosis of rotary machinery. Therefore, we developed a novel permanent magnetic angular acceleration sensor, which is without rotation angle limitations and could directly measure the instantaneous angular acceleration of the rotating system. The sensor rotor only needs to be coaxially connected with the rotating system, which enables convenient sensor installation. For the cup structure of the sensor rotor, it has a relatively small rotational inertia. Due to the unique mechanical structure of the sensor, the output signal of the sensor can be directed without a slip ring, which avoids signal weakening effect. In this paper, the operating principle of the sensor is described, and simulated using finite element method. The sensitivity of the sensor is calibrated by torsional pendulum and angle sensor, yielding an experimental result of about 0.88 mV/(rad·s−2. Finally, the angular acceleration of the actual rotating system has been tested, using both a single-phase asynchronous motor and a step motor. Experimental result confirms the operating principle of the sensor and indicates that the sensor has good practicability.

  15. Role of aging time on the magnetic properties of Sm2Co17 permanent magnets processed through cold isostatic pressing

    Science.gov (United States)

    Ramudu, M.; Rajkumar, D. M.

    2018-04-01

    The effect of aging time on the magnetic properties of Sm2Co17 permanent magnets processed through a novel method of cold isostatic pressing was investigated. Sintered Sm2Co17 samples were subjected to different aging times in the range of 10-30 h and their respective microstructures were correlated with the magnetic properties obtained. The values of remanant magnetization (Br) were observed to be constant in samples aged from 10-20 h beyond which a gradual decrease in Br values was observed. The values of coercivity (Hc) displayed a sharp increase in samples aged from 10 to 20 h beyond which the coercivity values showed marginal improvement. Hence a good combination of magnetic properties could be achieved in samples aged for 20 h. A maximum energy product of 27 MGOe was achieved in the 20 h aged sample processed through a novel route.

  16. 1998 Annual Study Report. Research and development of power storage by high-temperature superconducting flywheels (research and development of permanent magnet); 1998 nendo seika hokokusho. Koon chodendo flywheel denryoku chozo kenkyu kaihatsu (eikyu jishaku no kenkyu kaihatsu)

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-05-01

    The permanent magnets have been investigated and developed, for eventual commercialization of a 10 MWh power storage system by high-temperature superconducting flywheel. The permanent magnet rotors have been already developed in the previous years using a praseodymium-based magnet (Pr magnet) and neodymium-based sintered magnet (Nd sintered magnet), and the target rotational speed of 30,000 rpm has been attained. For development of the magnetic circuit to produce a stronger and smoother magnetic field, magnetic flux density of the Nd sintered magnet is measured. It shows a lower magnetic flux irregularity than the Pd magnet, but there is still room for further improvement. For development of large-size permanent magnet fabrication techniques, it is confirmed that the large-size Nd sintered magnet can be easily magnetized by partial magnetizing, as is the case with the Pr magnet. In this year, the irregular magnetic flux is three-dimensionally simulated, based on the results obtained in the previous years, to find that the simulated results are in good agreement with the observed ones. The measures to solve the problems are also investigated. It is also confirmed that the large-size ring magnet can be easily magnetized by partial magnetization. (NEDO)

  17. Iron free permanent magnet systems for charged particle beam optics

    International Nuclear Information System (INIS)

    Lund, S.M.; Halbach, K.

    1995-01-01

    The strength and astounding simplicity of certain permanent magnet materials allow a wide variety of simple, compact configurations of high field strength and quality multipole magnets. Here we analyze the important class of iron-free permanent magnet systems for charged particle beam optics. The theory of conventional segmented multipole magnets formed from uniformly magnetized block magnets placed in regular arrays about a circular magnet aperture is reviewed. Practical multipole configurations resulting are presented that are capable of high and intermediate aperture field strengths. A new class of elliptical aperture magnets is presented within a model with continuously varying magnetization angle. Segmented versions of these magnets promise practical high field dipole and quadrupole magnets with an increased range of applicability

  18. Method and apparatus for assembling permanent magnet rotors

    Science.gov (United States)

    Hsu, J.S.; Adams, D.J.

    1999-06-22

    A permanent magnet assembly for assembly in large permanent magnet motors and generators includes a two-piece carrier that can be slid into a slot in the rotor and then secured in place using a set screw. The invention also provides an auxiliary carrier device with guide rails that line up with the teeth of the rotor, so that a permanent magnet assembly can be pushed first into a slot, and then down the slot to its proper location. An auxiliary tool is provided to move the permanent magnet assembly into position in the slot before it is secured in place. Methods of assembling and disassembling the magnet assemblies in the rotor are also disclosed. 2 figs.

  19. Design and control of a superconducting permanent magnet synchronous motor

    International Nuclear Information System (INIS)

    Jiang, Y; Pei, R; Hong, Z; Song, J; Fang, F; Coombs, T A

    2007-01-01

    This paper gives a detailed description of the design of a superconducting permanent magnet synchronous motor. The parameters of the motor have been identified, and the torque equation has been stated. A direct torque control algorithm is introduced and applied to a traditional permanent magnet synchronous motor and the superconducting permanent magnet synchronous motor described in this paper. The motor performance shows that the direct torque control algorithm provides excellent control to the superconducting motor, and guarantees that the magnitude of the operational armature currents is smaller than the value of the critical current of the superconducting tape used for stator winding

  20. Design and control of a superconducting permanent magnet synchronous motor

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Y [Cambridge University Engineering Department, Trumpington Street, Cambridge CB2 1PZ (United Kingdom); Pei, R [Cambridge University Engineering Department, Trumpington Street, Cambridge CB2 1PZ (United Kingdom); Hong, Z [Cambridge University Engineering Department, Trumpington Street, Cambridge CB2 1PZ (United Kingdom); Song, J [Huazhong University of Science of Technology, Wuhan 430074 (China); Fang, F [Huazhong University of Science of Technology, Wuhan 430074 (China); Coombs, T A [Cambridge University Engineering Department, Trumpington Street, Cambridge CB2 1PZ (United Kingdom)

    2007-07-15

    This paper gives a detailed description of the design of a superconducting permanent magnet synchronous motor. The parameters of the motor have been identified, and the torque equation has been stated. A direct torque control algorithm is introduced and applied to a traditional permanent magnet synchronous motor and the superconducting permanent magnet synchronous motor described in this paper. The motor performance shows that the direct torque control algorithm provides excellent control to the superconducting motor, and guarantees that the magnitude of the operational armature currents is smaller than the value of the critical current of the superconducting tape used for stator winding.

  1. 77 FR 51046 - Certain Sintered Rare Earth Magnets, Methods of Making Same and Products Containing Same; Notice...

    Science.gov (United States)

    2012-08-23

    ... INTERNATIONAL TRADE COMMISSION [Docket No. 2908] Certain Sintered Rare Earth Magnets, Methods of... Certain Sintered Rare Earth Magnets, Methods of Making Same and Products Containing Same, DN 2908; the..., methods of making same and products [[Page 51047

  2. Samarium-cobalt type rare earth permanent magnets

    International Nuclear Information System (INIS)

    Kamat, S.V.

    2014-01-01

    Permanent magnets are one of the oldest and largest applications of magnetic materials and form an integral part of our modern industrial society. They belong to a special class of functional materials and are characterized for remanence (flux output from the magnet), coercivity (resistance to demagnetization) and energy product (material energy density) from the second quadrant of the magnetic hysteresis loop. The reliability, stability, size, weight, cost and performance of many electro-technical devices depend mainly on the properties of permanent magnets used in them. There are three important families of permanent magnets viz., Ferrites, Alnicos and Rare Earth Permanent Magnets (REPMs) with energy product values ranging from 3 to 50 MGOe and among the front ranking high performance REPMs, SmCo 5 , Sm 2 Co 17 type and NdFeB alloys are technologically the most important materials. They are used in a wide range of applications ranging from consumer products to very specialized areas of tele-communications, microelectronics, defence, space, avionics etc. While NdFeB has the highest energy product, Sm-Co based magnets are preferred for most critical applications where temperature stability of magnetic properties is essential because of their significantly higher Curie temperatures. In this presentation some of the key challenges associated with these Sm-Co based rare earth permanent magnets will be highlighted. (author)

  3. Multipactor Mitigation in Coaxial Lines by Means of Permanent Magnets

    CERN Document Server

    Gonzalez-Iglesias, D; Anza, S; Vague, J; Gimeno, B; Boria, V E; Raboso, D; Vicente, C; Gil, J; Caspers, F; Conde, L

    2014-01-01

    The main aim of this paper is the analysis of the feasibility of employing permanent magnets for the multipactor mitigation in a coaxial waveguide. First, the study of a coaxial line immersed in a uniform axial magnetic field shows that multipactor can be suppressed at any RF frequency if the external magnetic field is strong enough. Both theoretical simulations and experimental tests validate this statement. Next, multipactor breakdown of a coaxial line immersed in a hollow cylindrical permanent magnet is analyzed. Numerical simulations show that multipactor can be suppressed in a certain RF frequency range. The performed experimental test campaign demonstrates the capability of the magnet to avoid the multipactor electron multiplication process.

  4. A new type of permanent magnet ondulator and wiggler

    International Nuclear Information System (INIS)

    Jianming, X.; Maosan, L.; Qing, X.

    1987-01-01

    A new type of permanent magnet ondulator and wiggler is discussed. In this new design the magnet is composed of permanent magnet segments with modulated thickness. The magnetization directions of the segments are all perpendicular to the symmetrical plane of the magnet gap. By modulating the thicknesses of the segments, the field distribution is a pure sinusoidal curve in the ideal 2-dimensional case. The spatial expressions of the magnet field in the ideal case and in the real case are given. The methods for reducing the undesirable harmonics in the magnet field in the real case are discussed. Because of the arrangement of the magnetization directions of the magnet segments, soft iron shield can be used to strenghten the magnet field. In some cases, the stregnthening factor is more than two. The strenghtening effect of the soft iron shield is analysed also

  5. Wide gap, permanent magnet biased magnetic bearing system

    Science.gov (United States)

    Boden, Karl

    1992-01-01

    The unique features and applications of the presented electrical permanent magnetic bearing system essentially result from three facts: (1) the only bearing rotor components are nonlaminated ferromagnetic steel collars or cylinders; (2) all radial and axial forces are transmitted via radial gaps; and (3) large radial bearing gaps can be provided with minimum electric power consumption. The large gaps allow for effective encapsulation and shielding of the rotors at elevated or low temperatures, corrosive or ultra clean atmosphere or vacuum or high pressure environment. Two significant applications are described: (1) a magnetically suspended x ray rotary anode was operated under high vacuum conditions at 100 KV anode potential, 600 C temperature at the rotor collars and speed 18000 rpm with 13 mm radial bearing gap; and (2) an improved Czochralski type crystal growth apparatus using the hot wall method for pulling GaAs single crystals of low dislocation density. Both crystal and crucible are carried and transported by magnetically suspended shafts inside a hermetically sealed housing at 800 C shaft and wall temperature. The radial magnetic bearing gap measures 24 mm.

  6. Superstrong Adjustable Permanent Magnet for a Linear Collider Final Focus

    CERN Document Server

    Iwashita, Y

    2004-01-01

    Super-strong permanent magnets are being considered as one of the candidates for the final focus quadrupole magnets in a linear collider. A short prototype with temperature compensation included and variable strength capability has been designed and fabricated. Fabrication details and some magnetic measurement results will be presented.

  7. On the Motion of the Field of a Permanent Magnet

    Science.gov (United States)

    Leus, Vladimir; Taylor, Stephen

    2011-01-01

    A description is given of a series of recent experiments using a rotating magnetic circuit comprising a permanent magnet ring and yoke, and a stationary conductor in the air gap between the ring and yoke. The EMF induced in this case cannot be described by a simple application of Faraday's flux law. This is because the magnetic flux in the air gap…

  8. Anisotropic powder from sintered NdFeB magnets by the HDDR processing route

    Energy Technology Data Exchange (ETDEWEB)

    Sheridan, R.S.; Sillitoe, R.; Zakotnik, M.; Harris, I.R. [School of Metallurgy and Materials, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom); Williams, A.J., E-mail: a.j.williams@bham.ac.uk [School of Metallurgy and Materials, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom)

    2012-01-15

    Sintered NdFeB-based scrap magnets were recovered and processed using the HD and HDDR routes. The effects of varying the HDDR processing temperature were investigated (over the range 835-930 deg. C). The disproportion was carried out with a pressure ramp to a maximum of 1000 mbar hydrogen pressure with a 1 h hold time at each step and the optimum recombination conditions were set at 100 mbar with a 20 min hold time. Anisotropic NdFeB powder was produced in all cases with the best magnetic properties achieved at a processing temperature of 880 deg. C, producing powder with a remanence of 1.10({+-}0.02) T and an intrinsic coercivity of 800 ({+-}16) kA m{sup -1} and giving a (BH){sub max} of 129({+-}2.5) kJ m{sup -3}. - Highlights: > Production of anisotropic permanent magnet powder from scrap NdFeB magnets by HDDR. > Reaction pressure increases with increasing processing temperature. > Best magnetic properties achieved by processing at 880 deg. C.

  9. Anisotropic powder from sintered NdFeB magnets by the HDDR processing route

    International Nuclear Information System (INIS)

    Sheridan, R.S.; Sillitoe, R.; Zakotnik, M.; Harris, I.R.; Williams, A.J.

    2012-01-01

    Sintered NdFeB-based scrap magnets were recovered and processed using the HD and HDDR routes. The effects of varying the HDDR processing temperature were investigated (over the range 835-930 deg. C). The disproportion was carried out with a pressure ramp to a maximum of 1000 mbar hydrogen pressure with a 1 h hold time at each step and the optimum recombination conditions were set at 100 mbar with a 20 min hold time. Anisotropic NdFeB powder was produced in all cases with the best magnetic properties achieved at a processing temperature of 880 deg. C, producing powder with a remanence of 1.10(±0.02) T and an intrinsic coercivity of 800 (±16) kA m -1 and giving a (BH) max of 129(±2.5) kJ m -3 . - Highlights: → Production of anisotropic permanent magnet powder from scrap NdFeB magnets by HDDR. → Reaction pressure increases with increasing processing temperature. → Best magnetic properties achieved by processing at 880 deg. C.

  10. The influence of carbon and oxygen on the magnetic characteristics of press-less sintered NdFeB magnets

    DEFF Research Database (Denmark)

    Xia, Manlong; Abrahamsen, Asger Bech; Bahl, Christian

    2017-01-01

    The Pressless Process (PLP) was adopted to manufacture NdFeB sintered magnets, where the investigations on carbon and oxygen residues from heptane milling liquid media and graphite crucibles used for sintering were quantified to evaluate the influence on the magnetic characteristics. The carbon...

  11. Design, analysis and fabrication of a linear permanent magnet ...

    Indian Academy of Sciences (India)

    MONOJIT SEAL

    Linear permanent magnet synchronous machine; LPMSM—fabrication; design optimisation; finite-element ... induction motor (LIM) prototype was patented in 1890 [1]. Since then, linear ..... Also, for manual winding, more slot area is allotted to ...

  12. Self-suspended permanent magnetic FePt ferrofluids

    KAUST Repository

    Dallas, Panagiotis; Kelarakis, Antonios; Sahore, Ritu; DiSalvo, Francis J.; Livi, Sebastien; Giannelis, Emmanuel P.

    2013-01-01

    on the surface of L10 FePt nanoparticles. In contrast, all types of ferrofluids previously reported employ either volatile solvents as the suspending media or superparamagnetic iron oxide nanoparticles (that lacks permanent magnetization) as the inorganic

  13. Micromagnetics of rare-earth efficient permanent magnets

    Science.gov (United States)

    Fischbacher, Johann; Kovacs, Alexander; Gusenbauer, Markus; Oezelt, Harald; Exl, Lukas; Bance, Simon; Schrefl, Thomas

    2018-05-01

    The development of permanent magnets containing less or no rare-earth elements is linked to profound knowledge of the coercivity mechanism. Prerequisites for a promising permanent magnet material are a high spontaneous magnetization and a sufficiently high magnetic anisotropy. In addition to the intrinsic magnetic properties the microstructure of the magnet plays a significant role in establishing coercivity. The influence of the microstructure on coercivity, remanence, and energy density product can be understood by using micromagnetic simulations. With advances in computer hardware and numerical methods, hysteresis curves of magnets can be computed quickly so that the simulations can readily provide guidance for the development of permanent magnets. The potential of rare-earth reduced and rare-earth free permanent magnets is investigated using micromagnetic simulations. The results show excellent hard magnetic properties can be achieved in grain boundary engineered NdFeB, rare-earth magnets with a ThMn12 structure, Co-based nano-wires, and L10-FeNi provided that the magnet’s microstructure is optimized.

  14. Use of permanent magnets in accelerator technology: Present and future

    International Nuclear Information System (INIS)

    Halbach, K.

    1987-01-01

    Permanent magnet systems have some generic properties that, under some circumstances, make them not only mildy preferable over electromagnets, but make it possible to do things that can not be done with any other technology. After a general discussion of these generic advantages, some specific permanent magnet systems will be described. Special emphasis will be placed on systems that have now, or are likely to have in the future, a significant impact on how some materials research is conducted

  15. Permanent magnet material and process for producing the same

    International Nuclear Information System (INIS)

    Yoneyama, T.; Hori, T.; Ohima, T.

    1978-01-01

    This invention relates to an improvement of a permanent magnet material consisting, apart from impurities, of intermetallic compounds of the general formula of R 2 Co 17 , wherein the R component is at least one rare earth metal excluding radioactive elements and the Co component is cobalt. A suitable process to produce the permanent magnet material according to the invention is described. (U.K.)

  16. Implementation of Permanent Magnet Motors in Electric Vehicles

    OpenAIRE

    Elvestad, Eirik

    2008-01-01

    This thesis has studied permanent magnet motors in electric vehicles (EVs) under the assumption that they are tractable due to a low weight and high compactness. The implementation has been investigated through a case study, which resulted in an EV simulation model. The model contains a maximal torque per ampere and a closed-loop field weakening controller. Abstract Faults are a special concern in permanent magnet motors. Fault sources and faulted behavior are addressed separately. The EV mo...

  17. A tubular flux-switching permanent magnet machine

    Science.gov (United States)

    Wang, J.; Wang, W.; Clark, R.; Atallah, K.; Howe, D.

    2008-04-01

    The paper describes a novel tubular, three-phase permanent magnet brushless machine, which combines salient features from both switched reluctance and permanent magnet machine technologies. It has no end windings and zero net radial force and offers a high power density and peak force capability, as well as the potential for low manufacturing cost. It is, therefore, eminently suitable for a variety of applications, ranging from free-piston energy converters to active vehicle suspensions.

  18. Summary on Sensorless permanent magnet Brushless DC Motor Control Strategies

    Directory of Open Access Journals (Sweden)

    Li Hai Xia

    2016-01-01

    Full Text Available This paper aims at discussing the development process and application of permanent magnet brushless DC motor. By referring to the related literatures, this thesis gives an overview of several common non-position sensor detection technologies, analyzing their strengths and weaknesses as well as a number of new and improved methods in practical applications. Besides, The application situation of the electric door with sensorless permanent magnet brushless DC motor was illustrated.

  19. Exterior rotor permanent magnet generator in variable speed applications

    OpenAIRE

    Sattar, Rauf

    2016-01-01

    This thesis explores approaches for converting rotational mechanical power from diesel engines into electrical power of fixed frequency and voltage. Advances in high energy permanent magnets and power electronics are enabling technologies that provide opportunities for electrical machines with increased efficiency and compact size for variable speed power generation. The overall objective was to design a permanent magnet machine with concentrated winding that could be used in variable spe...

  20. Development of controlled solid-state alignment for alnico permanent magnets in near-final shape

    Directory of Open Access Journals (Sweden)

    Iver E. Anderson

    2017-05-01

    Full Text Available The 2011 price shock in the rare earth (RE permanent magnet (PM marketplace precipitated realization of extremely poor RE supply diversity and drove renewed research in RE-free permanent magnets such as “alnico.” Essentially, alnico is an Al-Ni-Co-Fe alloy with high magnetic saturation and TC, but low coercivity. It also was last researched extensively in the 1970’s. Currently alnico “9” magnets with the highest energy product (10MGOe are manufactured by directional solidification to make highly aligned anisotropic magnets. This work developed novel powder processing techniques to improve on unaligned anisotropic alnico “8H” with elevated coercivity. Gas atomization was used to produce pre-alloyed powder for binder-assisted compression molding of near-final shape magnets that were vacuum sintered to full density (250g showed reduced overall loop squareness compared to unaligned (equiaxed 8H due to grain rotation-induced misalignment, while low stresses improved squareness and greatly improved alignment compared to equiaxed magnets, with squareness approaching 0.30 and remanence ratio as high as 0.79.

  1. The magnetic properties of mill scale-derived permanent magnet

    International Nuclear Information System (INIS)

    Woon, H.S.; Hashim, M.M.; Yahya, N.; Zakaria, A.; Lim, K.P.

    2005-01-01

    In the permanent magnet SrO-FeO-Fe 2 O 3 system, there exist several magnetically ordered compounds with a stable phase at room temperature. The most important are the M(SrFe 12 O 19 ), X(SrFe 15 O 23 ) and W(SrFe 18 O 27 ) phases with hexagonal close packed structure. In this project, M(SrFe 12 O 19 ) was prepared using mill scale, a steel-maker byproduct, as raw material. The Malaysia steel industry generates approximately 30,000 metric tons of waste products such as mill scale every year. Transportation and disposal of the byproducts are costly and the environmental regulations are becoming stricter. Hence, local steel mills are to find new ways to recycle the waste as a feedstock for the steel-making process or as a saleable product. The M(SrFe 12 O 19 ) was synthesized using the conventional ceramic process. The formation of the SrFe 12 O 19 was confirmed by X-ray diffraction. The magnetic properties such as the energy product (BH)max, coercive force (iHc) and remanence (Br) were also reported in this paper. (Author)

  2. Design and simulation of permanent magnet synchronous motor control system

    Science.gov (United States)

    Li, Li; Liu, Yongqiu

    2018-06-01

    In recent years, with the development of power electronics, microelectronics, new motor control theory and rare earth permanent magnet materials, permanent magnet synchronous motors have been rapidly applied. Permanent magnet synchronous motors have the advantages of small size, low loss and high efficiency. Today, energy conservation and environmental protection are increasingly valued. It is very necessary to study them. Permanent magnet synchronous motor control system has a wide range of application prospects in the fields of electric vehicles, ships and other transportation. Using the simulation function of MATLAB/SIMULINK, a modular design structure was used to simulate the whole system model of speed loop adjustment, current PI modulation, SVPWM (Space Vector Pulse Width Module) wave generation and double closed loop. The results show that this control method has good robustness, and this method can improve the design efficiency and shorten the system design time. In this article, the analysis of the control principle of modern permanent magnet synchronous motor and the various processes of MATLAB simulation application will be analyzed in detail. The basic theory, basic method and application technology of the permanent magnet synchronous motor control system are systematically introduced.

  3. Permanent magnet with MgB{sub 2} bulk superconductor

    Energy Technology Data Exchange (ETDEWEB)

    Yamamoto, Akiyasu, E-mail: yamamoto@appchem.t.u-tokyo.ac.jp [The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656 (Japan); JST-PRESTO, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012 (Japan); Ishihara, Atsushi; Tomita, Masaru [Railway Technical Research Institute, 2-8-38 Hikari, Kokubunji, Tokyo 185-8540 (Japan); Kishio, Kohji [The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656 (Japan)

    2014-07-21

    Superconductors with persistent zero-resistance currents serve as permanent magnets for high-field applications requiring a strong and stable magnetic field, such as magnetic resonance imaging. The recent global helium shortage has quickened research into high-temperature superconductors (HTSs)—materials that can be used without conventional liquid-helium cooling to 4.2 K. Herein, we demonstrate that 40-K-class metallic HTS magnesium diboride (MgB{sub 2}) makes an excellent permanent bulk magnet, maintaining 3 T at 20 K for 1 week with an extremely high stability (<0.1 ppm/h). The magnetic field trapped in this magnet is uniformly distributed, as for single-crystalline neodymium-iron-boron. Magnetic hysteresis loop of the MgB{sub 2} permanent bulk magnet was determined. Because MgB{sub 2} is a simple-binary-line compound that does not contain rare-earth metals, polycrystalline bulk material can be industrially fabricated at low cost and with high yield to serve as strong magnets that are compatible with conventional compact cryocoolers, making MgB{sub 2} bulks promising for the next generation of Tesla-class permanent-magnet applications.

  4. High energy permanent magnets - Solutions to high performance devices

    International Nuclear Information System (INIS)

    Ma, B.M.; Willman, C.J.

    1986-01-01

    Neodymium iron boron magnets are a special class of magnets providing the highest level of performance with the least amount of material. Crucible Research Center produced the highest energy product magnet of 45 MGOe - a world record. Commercialization of this development has already taken place. Crucible Magnetics Division, located in Elizabethtown, Kentucky, is currently manufacturing and marketing six different grades of NdFeB magnets. Permanent magnets find application in motors, speakers, electron beam focusing devices for military and Star Wars. The new NdFeB magnets are of considerable interest for a wide range of applications

  5. Two cylinder permanent magnet stirrer for liquid metals

    Science.gov (United States)

    Bojarevičs, A.; Baranovskis, R.; Kaldre, I.; Milgrāvis, M.; Beinerts, T.

    2017-07-01

    To achieve a uniform liquid metal composition and temperature distribution, stirring is often necessary for industrial processes. Here, a novel permanent magnet system for liquid melt stirring is proposed. It promises very low energy consumption and options for multiple different flow types compared to traditional travelling magnetic field inductors or mechanical stirrers. The proposed system has a simple design: it consists of two rotating permanent magnet cylinders, which are magnetized transversely to the axis of the cylinders. The experimental device was developed and tested under various regimes using GaInSn alloy in a cylindrical crucible. Aluminum stirring by permanent magnets in laboratory scale is tested, and stirring impact on directional solidification of metallic alloys is experimentally investigated.

  6. Permanent-magnet-less machine having an enclosed air gap

    Science.gov (United States)

    Hsu, John S [Oak Ridge, TN

    2012-02-07

    A permanent magnet-less, brushless synchronous system includes a stator that generates a magnetic rotating field when sourced by an alternating current. An uncluttered rotor disposed within the magnetic rotating field is spaced apart from the stator to form an air gap relative to an axis of rotation. A stationary excitation core spaced apart from the uncluttered rotor by an axial air gap and a radial air gap substantially encloses the stationary excitation core. Some permanent magnet-less, brushless synchronous systems include stator core gaps to reduce axial flux flow. Some permanent magnet-less, brushless synchronous systems include an uncluttered rotor coupled to outer laminations. The quadrature-axis inductance may be increased in some synchronous systems. Some synchronous systems convert energy such as mechanical energy into electrical energy (e.g., a generator); other synchronous systems may convert any form of energy into mechanical energy (e.g., a motor).

  7. Nanostructured silicon ferromagnet collected by a permanent neodymium magnet.

    Science.gov (United States)

    Okuno, Takahisa; Thürmer, Stephan; Kanoh, Hirofumi

    2017-11-30

    Nanostructured silicon (N-Si) was prepared by anodic electroetching of p-type silicon wafers. The obtained magnetic particles were separated by a permanent neodymium magnet as a magnetic nanostructured silicon (mN-Si). The N-Si and mN-Si exhibited different magnetic properties: the N-Si exhibited ferromagnetic-like behaviour, whereas the mN-Si exhibited superparamagnetic-like behaviour.

  8. Theoretical validation for changing magnetic fields of systems of permanent magnets of drum separators

    Science.gov (United States)

    Lozovaya, S. Y.; Lozovoy, N. M.; Okunev, A. N.

    2018-03-01

    This article is devoted to the theoretical validation of the change in magnetic fields created by the permanent magnet systems of the drum separators. In the article, using the example of a magnetic separator for enrichment of highly magnetic ores, the method of analytical calculation of the magnetic fields of systems of permanent magnets based on the Biot-Savart-Laplace law, the equivalent solenoid method, and the superposition principle of fields is considered.

  9. Analysis of thermal demagnetization behavior of Nd–Fe–B sintered magnets using magnetic domain observation

    International Nuclear Information System (INIS)

    Takezawa, Masaaki; Ikeda, Soichiro; Morimoto, Yuji; Kabashima, Hisayuki

    2016-01-01

    We used magnetic domain observation to statistically observe the thermal demagnetization behavior of Nd–Fe–B sintered magnets at elevated temperatures up to 150 °C. Simultaneous magnetization reversal in a hundred adjacent grains occurred at 90 °C because of the magnetic interaction among the grains beyond grain boundaries in the Dysprosium (Dy)-free low-coercivity magnet. Conversely, simultaneous magnetization reversal in a hundred grains did not occur in the Dy-added high-coercivity magnets, and the demagnetizing ratio steadily increased with temperature. Furthermore, the addition of Dy induced high thermal stability by eliminating the simultaneous thermal demagnetization, which was caused by the magnetic interaction among the grains.

  10. Analysis of thermal demagnetization behavior of Nd–Fe–B sintered magnets using magnetic domain observation

    Energy Technology Data Exchange (ETDEWEB)

    Takezawa, Masaaki, E-mail: take@ele.kyutech.ac.jp; Ikeda, Soichiro; Morimoto, Yuji [Department of Applied Science for Integrated System Engineering, Faculty of Engineering, Kyushu Institute of Technology, 1-1 Sensui-cho, Tobata-ku, Kitakyushu, Fukuoka 804-8550 (Japan); Kabashima, Hisayuki [Mazda Motor Corporation,3-1, Shinchi, Fuchu-cho, Aki-gun Hiroshima 730-8670 (Japan)

    2016-05-15

    We used magnetic domain observation to statistically observe the thermal demagnetization behavior of Nd–Fe–B sintered magnets at elevated temperatures up to 150 °C. Simultaneous magnetization reversal in a hundred adjacent grains occurred at 90 °C because of the magnetic interaction among the grains beyond grain boundaries in the Dysprosium (Dy)-free low-coercivity magnet. Conversely, simultaneous magnetization reversal in a hundred grains did not occur in the Dy-added high-coercivity magnets, and the demagnetizing ratio steadily increased with temperature. Furthermore, the addition of Dy induced high thermal stability by eliminating the simultaneous thermal demagnetization, which was caused by the magnetic interaction among the grains.

  11. Effect of sintering temperature on magnetization and Mössbauer parameters of cobalt ferrite nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Chandra, Grish, E-mail: grishphysics@gmail.com [Department of Physics, DSB Campus Kumaun University, Nainital 263002, Uttarakhand (India); Srivastava, R.C. [Department of Physics, GB Pant University of Agriculture and Technology, Pantnagar, Uttarakhand (India); Reddy, V.R. [UGC-DAE CSR, Khandwa Road, DAVV Campus, Indore 452017, Madhya Pradesh (India); Agrawal, H.M. [Department of Physics, GB Pant University of Agriculture and Technology, Pantnagar, Uttarakhand (India)

    2017-04-01

    Nanoparticles of cobalt ferrite of different particle size were prepared using sol-gel method. Powder X-ray diffraction (XRD), transmission electron microscopy (TEM), vibrating sample magnetometer (VSM) and Mössbauer spectroscopy techniques were employed for characterization of nanoparticles for structural and magnetic properties. The particle size and saturation magnetization increase with the increase of sintering temperature. The saturation magnetization increases from 53 to 85 emu/g as the sintering temperature increases from 300 to 900 °C. The remanence increases while the coercivity decreases slightly with the increase of sintering temperature. Mössbauer spectra show the ferrimagnetic nature of all the samples and the cation distribution strictly depends on the sintering temperature. The stoichiometry of the cobalt ferrite formed was estimated to be (Co{sup 2+}{sub x}Fe{sup 3+}{sub 1−x})[Co{sup 2+}{sub 1−x}Fe{sup 3+}{sub 1+x}]O{sub 4}, based on our Mössbauer analysis. The inverse spinel structure gradually transforms towards the normal spinel structure as the sintering temperature increases. - Highlights: • After 500 °C sintering the cobalt ferrite shows complete crystallization. • An inversion sintering temperature between 900 °C and 1200 °C is proposed where the Fe{sup +3} again starts migration from B site to A site. • Sintering temperature is one of the prime factors which effect the magnetization and cation distribution between two sites A and B.

  12. Large permanent magnet quadrupoles for an electron storage ring

    International Nuclear Information System (INIS)

    Herb, S.W.

    1987-01-01

    We have built large high quality permanent magnet quadrupoles for use as interaction region quadrupoles in the Cornell Electron Storage Ring where they must operate in the 10 kG axial field of the CLEO experimental detector. We describe the construction and the magnetic measurement and tuning procedures used to achieve the required field quality and stability. (orig.)

  13. Magnetostatic interactions and forces between cylindrical permanent magnets

    Czech Academy of Sciences Publication Activity Database

    Vokoun, David; Beleggia, M.; Heller, Luděk; Šittner, Petr

    2009-01-01

    Roč. 321, č. 22 (2009), s. 3758-3763 ISSN 0304-8853 EU Projects: European Commission(XE) 46559 - CERINKA Institutional research plan: CEZ:AV0Z10100520 Keywords : cylinder * force measurement * magnetostatic * permanent magnet Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.204, year: 2009

  14. Mechanical design and fabrication of pure-permanent magnet undulator

    International Nuclear Information System (INIS)

    Chouksey, Sanjay; Vinit Kumar; Abhay Kumar; Krishnagopal, Srinivas

    2003-01-01

    A 50 mm period, 2.5 m long (50 periods), pure permanent magnet, variable gap undulator using NdFeB magnets is being built in two sections, each 1.25 m long. We present details of the mechanical design, fabrication experience, assembly and inspection of the undulator. (author)

  15. Periodic permanent magnet focusing system with high peak field

    International Nuclear Information System (INIS)

    Zhang Hong; Liu Weiwei; Bai Shuxin; Chen Ke

    2008-01-01

    In this study, hybrid periodic permanent magnet (PPM) system is studied, which has high axial magnetic field and low magnetic leakage. By simulation computation, some laws of magnetic field distribution vs. structure dimensions were obtained. A hybrid PPM is designed and constructed whose peak field reaches 0.6 T. The factors inducing discrepancies between computational results and practical measurements are analyzed. The magnetic field distribution is very sensitive to the variations of constructional parameters. Construction accuracy greatly influences the magnetic field distribution. Research results obtained here are potentially valuable for future work

  16. Use of permanent magnets in accelerator technology: Present and future

    International Nuclear Information System (INIS)

    Halbach, K.

    1987-05-01

    This report is a collection of viewgraphs discussing accelerator magnets. Permanent magnet systems have some generic properties that, under some circumstances, make them not only mildly preferable over electromagnets, but make it possible to do things that can not be done with any other technology. After a general discussion of these generic advantages, some specific permanent magnet systems will be described. Special emphasis will be placed on systems that have now, or are likely to have in the future, a significant impact on how some materials research is conducted. 4 refs., 33 figs

  17. Permanent-magnet material applications in particle accelerators

    International Nuclear Information System (INIS)

    Kraus, R.H. Jr.

    1992-01-01

    The modern charged particle accelerator has found application in a wide range of scientific research, industrial, medical, and defense fields. Researchers began to use permanent-magnet materials in particle accelerators soon after the invention of the alternating gradient principle, which showed that magnetic field could be used to control the transverse envelope of charged particle beams. The history of permanent-magnet use in accelerator physics and technology is outlined, current design methods and material properties of concern for particle accelerator applications are reviewed

  18. Comparison of adjustable permanent magnetic field sources

    DEFF Research Database (Denmark)

    Bjørk, Rasmus; Bahl, Christian Robert Haffenden; Smith, Anders

    2010-01-01

    be altered are analyzed using numerical simulations, and compared based on the generated magnetic flux density in a sample volume and the amount of magnet material used. The designs are the concentric Halbach cylinder, the two half Halbach cylinders, the two linear Halbach arrays and the four and six rod...... and the direction of the magnetic field are measured and compared with numerical simulation and a good agrement is found....

  19. Estimation of parameters of interior permanent magnet synchronous motors

    International Nuclear Information System (INIS)

    Hwang, C.C.; Chang, S.M.; Pan, C.T.; Chang, T.Y.

    2002-01-01

    This paper presents a magnetic circuit model to the estimation of machine parameters of an interior permanent magnet synchronous machine. It extends the earlier work of Hwang and Cho that focused mainly on the magnetic aspects of motor design. The proposed model used to calculate EMF, d- and q-axis reactances. These calculations are compared to those from finite element analysis and measurement with good agreement

  20. NdFeB permanent magnets with various Nd content

    Czech Academy of Sciences Publication Activity Database

    Žák, Tomáš; Talijan, N.; Ćosović, V.; Grujić, A.

    2008-01-01

    Roč. 113, č. 1 (2008), s. 279-282 ISSN 0587-4246. [Czech and Slovak Conference on Magnetism /13./ (CSMAG'07). Košice, 09.08.2007-12.08.2007] R&D Projects: GA MŠk 1M0512 Institutional research plan: CEZ:AV0Z20410507 Keywords : NdFeB permanent magnets * Mossbauer effect * X-ray Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.321, year: 2008

  1. Estimation of parameters of interior permanent magnet synchronous motors

    CERN Document Server

    Hwang, C C; Pan, C T; Chang, T Y

    2002-01-01

    This paper presents a magnetic circuit model to the estimation of machine parameters of an interior permanent magnet synchronous machine. It extends the earlier work of Hwang and Cho that focused mainly on the magnetic aspects of motor design. The proposed model used to calculate EMF, d- and q-axis reactances. These calculations are compared to those from finite element analysis and measurement with good agreement.

  2. Streaming flows produced by oscillating interface of magnetic fluid adsorbed on a permanent magnet in alternating magnetic field

    Science.gov (United States)

    Sudo, S.; Ito, M.; Ishimoto, Y.; Nix, S.

    2017-04-01

    This paper describes microstreaming flows generated by oscillating interface of magnetic fluid adsorbed on a circular cylindrical permanent magnet in alternating magnetic field. The interface of magnetic fluid adsorbed on the NdFeB magnet responds to the external alternating magnetic flied as harmonic oscillation. The directions of alternating magnetic field are parallel and antiparallel to the magnetic field of permanent magnet. The oscillation of magnetic fluid interface generates streaming flow around the magnet-magnetic fluid element in water. Microstreaming flows are observed with a high-speed video camera analysis system. The flow pattern generated by magnetic fluid motion depends on the Keulegan-Carpenter number and the Reynolds number.

  3. Large batch recycling of waste Nd–Fe–B magnets to manufacture sintered magnets with improved magnetic properties

    International Nuclear Information System (INIS)

    Li, X.T.; Yue, M.; Liu, W.Q.; Li, X.L.; Yi, X.F.; Huang, X.L.; Zhang, D.T.; Chen, J.W.

    2015-01-01

    The waste Nd–Fe–B sintered magnets up to 500 kg per batch were recycled to manufacture anisotropic sintered magnets by combination of hydrogen decrepitation (HD) and alloying technique. Magnetic properties and thermal stability of both the waste magnets and recycled magnets were investigated. The recycled magnet exhibits magnetic properties with remanence (B r ) of 12.38 kGs, coercivity (H ci ) of 24.89 kOe, and maximum energy product [(BH) max ] of 36.51 MGOe, respectively, which restores 99.20% of B r , 105.65% of H ci , and 98.65% of (BH) max of the waste magnets, respectively. The volume fraction of Nd-rich phase in the recycled magnets is about 10.1 vol.%, which is bigger than that of the waste magnets due to the additive of Nd 3 PrFe 14 B alloy containing more rare earth. The remanence temperature coefficient (α) and coercivity temperature coefficient (β) of the recycled magnets are −0.1155%/K and −0.5099%/K in the range of 288–423 K, respectively, which are comparative to those of the waste magnets. - Highlights: • Large batch recycling of waste Nd–Fe–B sintered magnets were performed. • The recycled magnet restores 99.20% of B r , 105.65% of H ci and 98.65% of (BH) max of the magnet. • The recycled magnets bears bigger volume fraction and better distribution of Nd-rich phase. • The recycled magnets exhibit similar temperature coefficients and maximum working temperature

  4. Design, manufacture and measurements of permanent dipole magnets for DIRAC

    CERN Document Server

    Vorozhtsov, A; Kasaei, S; Solodko, E; Thonet, P A; Tommasini, D

    2013-01-01

    The one of the aim of the DIRAC experiment is the observation of the long-lived π+π- atoms, using the proton beam of the CERN Proton Synchrotron [1]. Two dipole magnets are needed for the for the DIRAC experiment as high resolution spectrometers. The dipole magnet will be used to identify the long-lived atoms on the high level background of π+π- pairs produced simultaneously with π+π- atoms. The proposed design is a permanent magnet dipole with a mechanical aperture of 60 mm. The magnet, of a total physical length of 66 mm, is based on Sm2Co17 blocks and provides an integrated field strength of 24·10-3 T×m. The Sm2Co17 was chosen as a material for the permanent magnet blocks due to its radiation hardness and weaker temperature dependence. The magnetic field quality is determined by 2 ferromagnetic poles, aligned together with the permanent magnets blocks. The paper describes the design, manufacture and magnetic measurements of the magnets.

  5. Design and characterization of permanent magnetic solenoids for REGAE

    International Nuclear Information System (INIS)

    Hachmann, M.; Flöttmann, K.; Gehrke, T.; Mayet, F.

    2016-01-01

    REGAE is a small electron linear accelerator at DESY. In order to focus short and low charged electron bunches down to a few μm permanent magnetic solenoids were designed, assembled and field measurements were done. Due to a shortage of space close to the operation area an in-vacuum solution has been chosen. Furthermore a two-ring design made of wedges has been preferred in terms of beam dynamic issues. To keep the field quality of a piecewise built magnet still high a sorting algorithm for the wedge arrangement including a simple magnetic field model has been developed and used for the construction of the magnets. The magnetic field of these solenoids has been measured with high precision and compared to simulations. - Highlights: • presenting a two-ring radially magnetized permanent magnetic solenoid design. • development of a analytical field description and field quality factor. • development of a sorting algorithm for permanent magnetic pieces to form a magnet. • performing a high-precision field measurement of a high gradient field.

  6. The interaction between the permanent magnet and ceramic superconductor with organic filler

    International Nuclear Information System (INIS)

    Woźny, L; Kisiel, A; Garbera, A

    2016-01-01

    The aim of the study was to examine the phenomenon of magnetic levitation for YBaCuO superconducting samples in pure form and with epoxy resin content of 40%. Samples of superconductors were prepared by the standard reaction in the solid state. The forces of interaction between the superconductor and neodymium permanent magnet were measured. Samples with epoxy resin fillers had significantly smaller levitation force than the sample of the sintered superconductors. This is due to a much lower content of pure superconducting material in the sample volume (about 60% of the YBaCuO). However, the obvious advantage of such samples is the possibility of preparation superconductors with complicated shapes, eg. for use in a superconducting bearings or other devices. (paper)

  7. Asynchronous slip-ring motor synchronized with permanent magnets

    Directory of Open Access Journals (Sweden)

    Glinka Tadeusz

    2017-03-01

    Full Text Available The electric LSPMSM motor presented in the paper differs from standard induction motor by rotor design. The insulated start-up winding is located in slots along the rotor circumference. The winding ends are connected to the slip-rings. The rotor core contains permanent magnets. The electromechanical characteristics for synchronous operation were calculated, as were the start-up characteristics for operation with a short-circuited rotor winding. Two model motors were used for the calculations, the V-shaped Permanent Magnet (VPM – Fig. 3, and the Linear Permanent Magnet (IPM – Fig. 4, both rated at 14.5 kW. The advantages of the investigated motor are demonstrated in the conclusions.

  8. Dynamic Analysis of Permanent Magnet Synchronous Generator with Power Electronics

    Directory of Open Access Journals (Sweden)

    OZCIRA, S.

    2010-05-01

    Full Text Available Permanent magnet DC motor-generators (PMDC, PMSG have been widely used in industrial and energy sectors recently. Power control of these systems can be achieved by controlling the output voltage. In this study, PMDC-PMSG systems are mathematically modeled and simulated in MATLAB and Simulink software. Then the results are discussed. A low power permanent magnet synchronous generator is driven by a permanent magnet DC motor and the output voltage is controlled by a frequency cycle-converter. The output of a half-wave uncontrolled rectifier is applied to an SPWM inverter and the power is supplied to a 300V, 50Hz load. The load which is connected to an LC filter is modeled by state-space equations. LC filter is utilized in order to suppress the voltage oscillations at the inverter output.

  9. Novel ocean energy permanent magnet linear generator buoy

    Energy Technology Data Exchange (ETDEWEB)

    Rhinefrank, K.; Agamloh, E.B.; Jouanne, A. von; Wallace, A.K.; Prudell, J.; Kimble, K.; Aills, J.; Schmidt, E.; Schacher, A. [School of Electrical Engineering and Computer Science, Oregon State University, Corvallis, OR 97331-3211 (United States); Chan, P.; Sweeny, B. [Department of Mechanical Engineering, Oregon State University, Corvallis, OR 97331-3211 (United States)

    2006-07-15

    This paper describes the research, design, construction and prototype testing process of a novel ocean energy direct drive permanent magnet linear generator buoy. The buoy employs the vertical component of the motion of ocean waves to power a linear generator. The generator consists of a permanent magnet field system (mounted on the central translator shaft) and an armature, in which the power is generated (mounted on the buoy). The translator shaft is anchored to the sea floor, and the buoy/floater moves armature coils relative to the permanent magnet translator to induce voltages. The electrical and mechanical structures of the buoy generator are provided, along with performance characteristics, including voltage, current and developed power. (author)

  10. Special-Purpose High-Torque Permanent-Magnet Motors

    Science.gov (United States)

    Doane, George B., III

    1995-01-01

    Permanent-magnet brushless motors that must provide high commanded torques and satisfy unusual heat-removal requirement are developed. Intended for use as thrust-vector-control actuators in large rocket engines. Techniques and concepts used to design improved motors for special terrestrial applications. Conceptual motor design calls for use of rotor containing latest high-energy-product rare-earth permanent magnets so that motor produces required torque while drawing smallest possible currents from power supply. Torque generated by electromagnetic interaction between stator and permanent magnets in rotor when associated electronic circuits applied appropriately temporally and spatially phased currents to stator windings. Phase relationships needed to produce commanded torque computed in response to torque command and to electronically sensed angular position of rotor relative to stator.

  11. Permanent Magnetic System Design for the Wall-Climbing Robot

    Directory of Open Access Journals (Sweden)

    W. Shen

    2006-01-01

    Full Text Available This paper presents the design and analysis of the permanent magnetic system for a wall-climbing robot with permanent magnetic tracks. Based on the behaviour of gecko lizards, the architecture of the robot was designed and built, including the structure of the adhesion mechanism, the mechanical architecture and the anti-toppling mechanism. The permanent magnetic adhesion mechanism and the tracked locomotion mechanism were employed in this kind of wall-climbing robot. Through static and dynamic force analysis of the robot under different situations, design requirements for the adhesion mechanism were derived. Two different types of structures were put forward for the permanent magnetic units and are further discussed in this paper. These two types of structures are also analysed in detail. In addition, a finite-element method was used to verify the results of magnetic units. Finally, two wall-climbing robots, equipped with different magnetic systems described previously, are explained and their applications are discussed in this paper.

  12. The mechanism of Tc performance for Zn doped MgB2 sintered in magnetic field

    International Nuclear Information System (INIS)

    Li, W.X.; Li, Y.; Chen, R.H.; Zeng, R.; Dou, S.X.

    2010-01-01

    The mechanism of magnetic field sintering on the critical transition temperature, T c , for the Zn doped MgB 2 superconductor was investigated with the observation of Raman scattering measurement and the Raman spectra fit analysis. The broadened E 2g mode in Raman spectra shows the strengthening of the electron-phonon coupling (EPC) for the sample sintered in magnetic field. A synchronous fluctuation is observed between the Raman characters of the E 2g mode and the T c .

  13. Effect of sintering conditions on the magnetic disaccommodation in barium M-type hexaferrites

    International Nuclear Information System (INIS)

    Hernandez-Gomez, Pablo; Torres, Carlos; Francisco, Carlos de; Munoz, Jose Maria; Alejos, Oscar; Iniguez, Jose Ignacio; Raposo, Victor; Montero, Oscar

    2006-01-01

    The relaxation of the initial magnetic permeability has been measured in polycrystalline hexaferrites with nominal composition BaO.6Fe 2 O 3 (i.e. M-type). The samples have been sintered at different temperatures in CO 2 atmosphere and with different manufacturing conditions. In temperature range between 80 and 500 K, the magnetic disaccommodation shows presence of different relaxation processes, depending on both the sintering temperature and sintering time. The analogies and differences between the results obtained are discussed in terms of similar phase formation and different crystallite size

  14. Experiences with permanent magnets at the Fermilab recycler ring

    International Nuclear Information System (INIS)

    Volk, James T

    2011-01-01

    In order to achieve higher luminosities in Run II a separate antiproton storage ring was built in the Main Injector tunnel. To reduce both construction and operations costs permanent magnets were used. This paper discusses the design criterion and specifications, including temperature dependence, longitudinal uniformity, and adjusting of the higher harmonics of the magnets. The design tolerances for a storage ring are more stringent than for a single pass beam line. The difference between the measured and ideal central field for each magnet was held to better than 0.1%. The temperature stability for all magnets was set to better than 0.01% per degree Celsius. Higher order harmonics relative to the central field were set to less than 0.01%. This was done for all 484 permanent magnet that were built.

  15. Variable-field permanent-magnet quadrupole for the SSC

    International Nuclear Information System (INIS)

    Barlow, D.B.; Kraus, R.H. Jr.; Martinez, R.P.; Meyer, R.E.

    1994-01-01

    A set of compact variable-field permanent-magnet quadrupoles have been designed, fabricated, and tested for use in the SSC linac matching section. The quadrupoles have 24 mm-diameter apertures and 40 mm-long poles. The hybrid (permanent-magnet and iron) design, uses a fixed core of magnet material (NdFeB) and iron (C-1006) surrounded by a rotating ring of the same magnet material and iron. The quadrupole gradient-length product can be smoothly varied from a minimum of 0.7 T up to a maximum of 4.3 T by a 90 degree rotation of the outer ring of iron and magnet material

  16. Hybrid-secondary uncluttered permanent magnet machine and method

    Science.gov (United States)

    Hsu, John S.

    2005-12-20

    An electric machine (40) has a stator (43), a permanent magnet rotor (38) with permanent magnets (39) and a magnetic coupling uncluttered rotor (46) for inducing a slip energy current in secondary coils (47). A dc flux can be produced in the uncluttered rotor when the secondary coils are fed with dc currents. The magnetic coupling uncluttered rotor (46) has magnetic brushes (A, B, C, D) which couple flux in through the rotor (46) to the secondary coils (47c, 47d) without inducing a current in the rotor (46) and without coupling a stator rotational energy component to the secondary coils (47c, 47d). The machine can be operated as a motor or a generator in multi-phase or single-phase embodiments and is applicable to the hybrid electric vehicle. A method of providing a slip energy controller is also disclosed.

  17. A novel permanent magnetic rail for HTS levitation propulsion system

    International Nuclear Information System (INIS)

    Guo, F.; Tang, Y.; Ren, L.; Li, J.

    2009-01-01

    The Halbach Array has a characteristic advantage that the spatial fundamental field is canceled on one side of the array while the field intensity on the other side is enhanced. So this array could be used in the design of high temperature superconducting permanent magnetic levitation rail to improve the surface magnetic field and levitation force. This paper compared the surface magnetic field of the Halbach Array rail and two conventional levitation rails at first. Then proposed the potential advantages of Halbach Array applied in permanent magnetic rail system. But the Halbach Array rail is mechanical instability. An novel improved Halbach Array rail is proposed in this paper. The new structure combined the advantages of traditional structure and Halbach Array structure, solved the problem of mechanical instability, and carried on the advantage of Halbach Array on the magnetic field distribution at the same time.

  18. A variable-field permanent-magnet dipole for accelerators

    International Nuclear Information System (INIS)

    Kraus, R.H. Jr.; Barlow, D.B.; Meyer, R.

    1992-01-01

    A new concept for a variable-field permanent-magnet dipole has been developed and fabricated at Los Alamos. The application requires an extremely uniform dipole field in the magnet aperture and precision variability over a large operating range. An iron-core permanent- magnet design using a shunt that was specially shaped to vary the field in a precise and reproducible fashion with shunt position. The key to this design is in the shape of the shunt. The field as a function of shunt position is very linear from 90% of the maximum field to 20% of the minimum field. The shaped shunt also results in a small maximum magnetic force attracting the shunt to the yoke allowing a simple mechanical design. Calculated and measured results agree well for the magnet

  19. Variable-field permanent magnet quadrupole for the SSC

    International Nuclear Information System (INIS)

    Barlow, D.B.; Kraus, R.H. Jr.; Martinez, R.P.; Meyer, R.E.

    1993-01-01

    A set of compact variable-field permanent-magnet quadrupoles have been designed, fabricated, and tested for use In the SSC linac matching section. The quadrupoles have 24 mm-diameter apertures and 40 mm-long poles. The hybrid (permanent-magnet and iron) design, uses a fixed core of magnet material (NdFeB) and iron (C-1006) surrounded by a rotating ring of the same magnet material and iron. The quadrupole gradient-length product can be smoothly varied from a minimum of 0.7 T up to a maximum, of 4.3 T by a 90 degrees rotation of the outer ring of iron and magnet material

  20. Nd-Fe-B sintered magnets fabrication by using atomized powders

    International Nuclear Information System (INIS)

    Goto, R; Sugimoto, S; Matsuura, M; Tezuka, N; Une, Y; Sagawa, M

    2011-01-01

    Nd-Fe-B sintered magnets are required to achieve high coercivity for improvement of their thermal stability. Dy is added to increase coercivity, however, this element decrease magnetization and energy products. Therefore, Dy-lean Nd-Fe-B sintered magnets with high coercivity are strongly demanded. To increase coercivity, it is necessary that microstructure of sintered magnets is consisted of both fine main phase particles and homogeneously distributed Nd-rich phases around the main phase. To meet those requirements, Nd-Fe-B atomized powders were applied to the fabrication process of sintered magnets. Comparing with the case of using strip casting (SC) alloys, jet-milled powders from atomized powders show homogeneous distribution of Nd-rich phase. After optimized thermal treatment, coercivities of sintered magnets from atomized powders and SC alloys reach 1050 kA·m-1 and 1220 kA·m-1, respectively. This difference in coercivity was due to initial oxygen concentration of starting materials. Consequently, Nd-rich phases became oxides with high melting points, and did not melt and spread during sintering and annealing.

  1. Permanent magnets composed of high temperature superconductors

    Science.gov (United States)

    Weinstein, Roy; Chen, In-Gann; Liu, Jay; Lau, Kwong

    1991-01-01

    A study of persistent, trapped magnetic field has been pursued with high-temperature superconducting (HTS) materials. The main effort is to study the feasibility of utilization of HTS to fabricate magnets for various devices. The trapped field, when not in saturation, is proportional to the applied field. Thus, it should be possible to replicate complicated field configurations with melt-textured YBa2Cu3O7 (MT-Y123) material, bypassing the need for HTS wires. Presently, materials have been developed from which magnets of 1.5 T, at 77 K, can be fabricated. Much higher field is available at lower operating temperature. Stability of a few percent per year is readily attainable. Results of studies on prototype motors and minimagnets are reported.

  2. Controlling chaos in the permanent magnet synchronous motor

    International Nuclear Information System (INIS)

    Zribi, Mohamed; Oteafy, Ahmed; Smaoui, Nejib

    2009-01-01

    The Permanent Magnet Synchronous Motor (PMSM) is known to exhibit chaotic behavior under certain conditions. This paper proposes to use an instantaneous Lyapunov exponent control algorithm to control the PMSM. One of the objectives of the control approach is to bring order to the PMSM and to drive it to any user-defined desired state. Simulation results under different operating conditions indicate that the proposed control scheme works well. Moreover, the proposed Lyapunov exponent control scheme is able to induce chaos on the permanent magnet synchronous motor. Simulation results show the effectiveness of the proposed control scheme in chaotifing the response of the motor.

  3. Tests of planar permanent magnet multipole focusing elements

    International Nuclear Information System (INIS)

    Cobb, J.; Tatchyn, R.

    1993-08-01

    In recent work, planar configurations of permanent magnets were proposed as substitutes for conventional current-driven iron quadrupoles in applications limited by small aperture sizes and featuring small beam occupation diameters. Important examples include the configuring of focusing lattices in small-gap insertion devices, and the implementation of compact mini-beta sections on linear or circular machines. In subsequent analysis, this approach was extended to sextupoles and higher-order multipoles. In this paper we report on initial measurements conducted at the Stanford Linear Accelerator Center on recently fabricated planar permanent magnet quadrupoles and sextupoles configured out of SmCo and NdFe/B

  4. Miniature high speed compressor having embedded permanent magnet motor

    Science.gov (United States)

    Zhou, Lei (Inventor); Zheng, Liping (Inventor); Chow, Louis (Inventor); Kapat, Jayanta S. (Inventor); Wu, Thomas X. (Inventor); Kota, Krishna M. (Inventor); Li, Xiaoyi (Inventor); Acharya, Dipjyoti (Inventor)

    2011-01-01

    A high speed centrifugal compressor for compressing fluids includes a permanent magnet synchronous motor (PMSM) having a hollow shaft, the being supported on its ends by ball bearing supports. A permanent magnet core is embedded inside the shaft. A stator with a winding is located radially outward of the shaft. The PMSM includes a rotor including at least one impeller secured to the shaft or integrated with the shaft as a single piece. The rotor is a high rigidity rotor providing a bending mode speed of at least 100,000 RPM which advantageously permits implementation of relatively low-cost ball bearing supports.

  5. Design Considerations of Permanent Magnet Transverse Flux Machines

    DEFF Research Database (Denmark)

    Lu, Kaiyuan; Rasmussen, Peter Omand; Ritchie, Ewen

    2011-01-01

    electrical machines. This paper addresses two important design considerations for PMTFM—the influence of permanent magnet leakage flux, which plays an important role in the determination of machine output torque, and the leakage inductance. A new simple method to provide a quick estimation of the armature......Permanent magnet transverse flux machine (PMTFM) is well known for its high torque density and is interested in various direct-drive applications. Due to its complicated 3-D flux components, design and design optimization of a PMTFM is more difficult and time consuming than for radial flux...

  6. Investigation of the magnetic field of the permanent magnet applied in the DIRAC experiment

    CERN Document Server

    Batyuk, P; Yazkov, V

    2012-01-01

    An analysis of the experimental data obtained during the run of 2011 has revealed the effect of degradation of the permanent magnet used. This effect is investigated, and average magnetic field is estimated for each day of the run.

  7. Design and analysis of tubular permanent magnet linear wave generator.

    Science.gov (United States)

    Si, Jikai; Feng, Haichao; Su, Peng; Zhang, Lufeng

    2014-01-01

    Due to the lack of mature design program for the tubular permanent magnet linear wave generator (TPMLWG) and poor sinusoidal characteristics of the air gap flux density for the traditional surface-mounted TPMLWG, a design method and a new secondary structure of TPMLWG are proposed. An equivalent mathematical model of TPMLWG is established to adopt the transformation relationship between the linear velocity of permanent magnet rotary generator and the operating speed of TPMLWG, to determine the structure parameters of the TPMLWG. The new secondary structure of the TPMLWG contains surface-mounted permanent magnets and the interior permanent magnets, which form a series-parallel hybrid magnetic circuit, and their reasonable structure parameters are designed to get the optimum pole-arc coefficient. The electromagnetic field and temperature field of TPMLWG are analyzed using finite element method. It can be included that the sinusoidal characteristics of air gap flux density of the new secondary structure TPMLWG are improved, the cogging force as well as mechanical vibration is reduced in the process of operation, and the stable temperature rise of generator meets the design requirements when adopting the new secondary structure of the TPMLWG.

  8. Design and Analysis of Tubular Permanent Magnet Linear Wave Generator

    Directory of Open Access Journals (Sweden)

    Jikai Si

    2014-01-01

    Full Text Available Due to the lack of mature design program for the tubular permanent magnet linear wave generator (TPMLWG and poor sinusoidal characteristics of the air gap flux density for the traditional surface-mounted TPMLWG, a design method and a new secondary structure of TPMLWG are proposed. An equivalent mathematical model of TPMLWG is established to adopt the transformation relationship between the linear velocity of permanent magnet rotary generator and the operating speed of TPMLWG, to determine the structure parameters of the TPMLWG. The new secondary structure of the TPMLWG contains surface-mounted permanent magnets and the interior permanent magnets, which form a series-parallel hybrid magnetic circuit, and their reasonable structure parameters are designed to get the optimum pole-arc coefficient. The electromagnetic field and temperature field of TPMLWG are analyzed using finite element method. It can be included that the sinusoidal characteristics of air gap flux density of the new secondary structure TPMLWG are improved, the cogging force as well as mechanical vibration is reduced in the process of operation, and the stable temperature rise of generator meets the design requirements when adopting the new secondary structure of the TPMLWG.

  9. Design and Analysis of Tubular Permanent Magnet Linear Wave Generator

    Science.gov (United States)

    Si, Jikai; Feng, Haichao; Su, Peng; Zhang, Lufeng

    2014-01-01

    Due to the lack of mature design program for the tubular permanent magnet linear wave generator (TPMLWG) and poor sinusoidal characteristics of the air gap flux density for the traditional surface-mounted TPMLWG, a design method and a new secondary structure of TPMLWG are proposed. An equivalent mathematical model of TPMLWG is established to adopt the transformation relationship between the linear velocity of permanent magnet rotary generator and the operating speed of TPMLWG, to determine the structure parameters of the TPMLWG. The new secondary structure of the TPMLWG contains surface-mounted permanent magnets and the interior permanent magnets, which form a series-parallel hybrid magnetic circuit, and their reasonable structure parameters are designed to get the optimum pole-arc coefficient. The electromagnetic field and temperature field of TPMLWG are analyzed using finite element method. It can be included that the sinusoidal characteristics of air gap flux density of the new secondary structure TPMLWG are improved, the cogging force as well as mechanical vibration is reduced in the process of operation, and the stable temperature rise of generator meets the design requirements when adopting the new secondary structure of the TPMLWG. PMID:25050388

  10. Synchronous motor with hybrid permanent magnets on the rotor.

    Science.gov (United States)

    Slusarek, Barbara; Kapelski, Dariusz; Antal, Ludwik; Zalas, Pawel; Gwoździewicz, Maciej

    2014-07-10

    Powder metallurgy allows designers of electric motors to implement new magnetic circuit structures. A relatively new concept is the use of a magnet system consisting of various types of magnets on one rotor, for example sintered and bonded magnets. This concept has been applied to the design and manufacture of the four-pole rotor of a synchronous motor with 400 W power and a rotational speed of 1500 rpm. In this motor, the stator of an asynchronous motor type Sh 71-4B is applied. The application of the new construction of the rotor resulted in an increase in motor efficiency and power factor compared to an asynchronous motor with the same volume.

  11. Synchronous Motor with Hybrid Permanent Magnets on the Rotor

    Directory of Open Access Journals (Sweden)

    Barbara Slusarek

    2014-07-01

    Full Text Available Powder metallurgy allows designers of electric motors to implement new magnetic circuit structures. A relatively new concept is the use of a magnet system consisting of various types of magnets on one rotor, for example sintered and bonded magnets. This concept has been applied to the design and manufacture of the four-pole rotor of a synchronous motor with 400 W power and a rotational speed of 1500 rpm. In this motor, the stator of an asynchronous motor type Sh 71-4B is applied. The application of the new construction of the rotor resulted in an increase in motor efficiency and power factor compared to an asynchronous motor with the same volume.

  12. CALCULATION OF INDUCTANCE OF THE INTERIOR PERMANENT MAGNET SYNCHRONOUS MOTOR

    Directory of Open Access Journals (Sweden)

    Phyong Le Ngo

    2017-01-01

    Full Text Available Interior permanent magnet synchronous motor (IPMSM refers to salient-pole synchronous motors, characterized by inequality of inductances of longitudinal (d and transverse (q axes. Electromagnetic torque of IPMSM consists of two components: active torque and reactive torque; the latter depends on inductances of d and q axes. An analytical method to calculate own inductances and mutual inductances of a three-phase IPMSM is presented. Distributed windings of the stator are substituted by equivalent sine distributed windings. An interior permanent magnets rotor is substituted by an equivalent salient-pole rotor. Sections of a magnetic circuit comprising interior permanent magnets, air barriers and steel bridges are substituted by equivalent air-gap. The expressions of the magnetic induction created by current of the stator windings at each point of the air gap as well as of magnetic flux linkage of the stator windings have been obtained. The equations of the self-inductances of phases A, B, C, and of inductance of mutual induction are determined from magnetic flux linkage. The inductance of the d and q axes have been obtained as a result of transformation of the axes abc–dq. The results obtained with the use of the proposed analytical method and the finite element method are presented in the form of a graph; the calculations that have been obtained by these two methods were compared. 

  13. Non linear permanent magnets modelling with the finite element method

    International Nuclear Information System (INIS)

    Chavanne, J.; Meunier, G.; Sabonnadiere, J.C.

    1989-01-01

    In order to perform the calculation of permanent magnets with the finite element method, it is necessary to take into account the anisotropic behaviour of hard magnetic materials (Ferrites, NdFeB, SmCo5). In linear cases, the permeability of permanent magnets is a tensor. This one is fully described with the permeabilities parallel and perpendicular to the easy axis of the magnet. In non linear cases, the model uses a texture function which represents the distribution of the local easy axis of the cristallytes of the magnet. This function allows a good representation of the angular dependance of the coercitive field of the magnet. As a result, it is possible to express the magnetic induction B and the tensor as functions of the field and the texture parameter. This model has been implemented in the software FLUX3D where the tensor is used for the Newton-Raphson procedure. 3D demagnetization of a ferrite magnet by a NdFeB magnet is a suitable representative example. They analyze the results obtained for an ideally oriented ferrite magnet and a real one using a measured texture parameter

  14. Permanent magnet steerers for canted undulators at the ESRF

    Energy Technology Data Exchange (ETDEWEB)

    Le Bec, G., E-mail: lebec@esrf.fr [ESRF, 6 r. J. Horowitz, BP 220, 38043 Grenoble Cedex 9 (France); Chavanne, J. [ESRF, 6 r. J. Horowitz, BP 220, 38043 Grenoble Cedex 9 (France)

    2012-02-01

    A number of canted undulators will be installed at the ESRF. Permanent Magnet Steerers will be used for providing canting angles up to 5.4 mrad. These steerers have been optimized in view of the limited space available and the required field quality. The magnetic interaction between the steerers and the undulators may lead to additional optical phase errors: auxiliary poles have been added to obtain a fast decrease of the fringe field. The transverse homogeneity of the magnetic field integral is another strong design constraint. Good homogeneity was reached by optimizing the profiles of the iron poles. Eight steerers have been constructed and magnetic measurements have been performed.

  15. High speed operation of permanent magnet machines

    Science.gov (United States)

    El-Refaie, Ayman M.

    This work proposes methods to extend the high-speed operating capabilities of both the interior PM (IPM) and surface PM (SPM) machines. For interior PM machines, this research has developed and presented the first thorough analysis of how a new bi-state magnetic material can be usefully applied to the design of IPM machines. Key elements of this contribution include identifying how the unique properties of the bi-state magnetic material can be applied most effectively in the rotor design of an IPM machine by "unmagnetizing" the magnet cavity center posts rather than the outer bridges. The importance of elevated rotor speed in making the best use of the bi-state magnetic material while recognizing its limitations has been identified. For surface PM machines, this research has provided, for the first time, a clear explanation of how fractional-slot concentrated windings can be applied to SPM machines in order to achieve the necessary conditions for optimal flux weakening. A closed-form analytical procedure for analyzing SPM machines designed with concentrated windings has been developed. Guidelines for designing SPM machines using concentrated windings in order to achieve optimum flux weakening are provided. Analytical and numerical finite element analysis (FEA) results have provided promising evidence of the scalability of the concentrated winding technique with respect to the number of poles, machine aspect ratio, and output power rating. Useful comparisons between the predicted performance characteristics of SPM machines equipped with concentrated windings and both SPM and IPM machines designed with distributed windings are included. Analytical techniques have been used to evaluate the impact of the high pole number on various converter performance metrics. Both analytical techniques and FEA have been used for evaluating the eddy-current losses in the surface magnets due to the stator winding subharmonics. Techniques for reducing these losses have been

  16. Magnetic levitation force between a superconducting bulk magnet and a permanent magnet

    International Nuclear Information System (INIS)

    Wang, J J; He, C Y; Meng, L F; Li, C; Han, R S; Gao, Z X

    2003-01-01

    The current density J(ρ, z) in a disc-shaped superconducting bulk magnet and the magnetic levitation force F SBM z exerted on the superconducting bulk magnet by a cylindrical permanent magnet are calculated from first principles. The effect of the superconducting parameters of the superconducting bulk is taken into account by assuming the voltage-current law E = E c (J/J c ) n and the material law B = μ 0 H. The magnetic levitation force F SBM z is dominated by the remnant current density J' 2 (ρ, z), which is induced by switching off the applied magnetizing field. High critical current density and flux creep exponent may increase the magnetic levitation force F SBM z . Large volume and high aspect ratio of the superconducting bulk can further enhance the magnetic levitation force F SBM z

  17. Optimal Design Solutions for Permanent Magnet Synchronous Machines

    Directory of Open Access Journals (Sweden)

    POPESCU, M.

    2011-11-01

    Full Text Available This paper presents optimal design solutions for reducing the cogging torque of permanent magnets synchronous machines. A first solution proposed in the paper consists in using closed stator slots that determines a nearly isotropic magnetic structure of the stator core, reducing the mutual attraction between permanent magnets and the slotted armature. To avoid complications in the windings manufacture technology the stator slots are closed using wedges made of soft magnetic composite materials. The second solution consists in properly choosing the combination of pole number and stator slots number that typically leads to a winding with fractional number of slots/pole/phase. The proposed measures for cogging torque reduction are analyzed by means of 2D/3D finite element models developed using the professional Flux software package. Numerical results are discussed and compared with experimental ones obtained by testing a PMSM prototype.

  18. Rational design of the exchange-spring permanent magnet.

    Science.gov (United States)

    Jiang, J S; Bader, S D

    2014-02-12

    The development of the optimal exchange-spring permanent magnet balances exchange hardening, magnetization enhancement, and the feasibility of scalable fabrication. These requirements can be met with a rational design of the microstructural characteristics. The magnetization processes in several model exchange-spring structures with different geometries have been analyzed with both micromagnetic simulations and nucleation theory. The multilayer geometry and the soft-cylinders-in-hard-matrix geometry have the highest achievable figure of merit (BH)max, while the soft-spheres-in-hard-matrix geometry has the lowest upper limit for (BH)max. The cylindrical geometry permits the soft phase to be larger and does not require strict size control. Exchange-spring permanent magnets based on the cylindrical geometry may be amenable to scaled-up fabrication.

  19. Rational design of the exchange-spring permanent magnet

    International Nuclear Information System (INIS)

    Jiang, J S; Bader, S D

    2014-01-01

    The development of the optimal exchange-spring permanent magnet balances exchange hardening, magnetization enhancement, and the feasibility of scalable fabrication. These requirements can be met with a rational design of the microstructural characteristics. The magnetization processes in several model exchange-spring structures with different geometries have been analyzed with both micromagnetic simulations and nucleation theory. The multilayer geometry and the soft-cylinders-in-hard-matrix geometry have the highest achievable figure of merit (BH) max , while the soft-spheres-in-hard-matrix geometry has the lowest upper limit for (BH) max . The cylindrical geometry permits the soft phase to be larger and does not require strict size control. Exchange-spring permanent magnets based on the cylindrical geometry may be amenable to scaled-up fabrication. (paper)

  20. Effect of grain alignment distribution on magnetic properties in (MM, Nd)-Fe-B sintered magnets

    Science.gov (United States)

    Yu, Xiaoqiang; Yue, Ming; Zhu, Minggang; Liu, Weiqiang; Li, Yuqing; Xi, Longlong; Li, Jiajie; Zhang, Jiuxing; Li, Wei

    2018-03-01

    H cj of (MM x Nd1-x )-Fe-B sintered magnets decreases distinctly with x increasing when misch metal (MM) content (x) ranges from 0.3 to 1. Practical application is taken into consideration so that the (MM0.6Nd0.4)-Fe-B components are chosen to analyze the changes in behavior of the magnetic properties. Both Magnet II and Magnet III belong to (MM0.6Nd0.4)-Fe-B sintered magnets, however, it should be noted that Magnet II is prepared by the single alloying method (SAM) and Magnet III is prepared by the double main phase alloy method (DMPAM). Core-shell structures of the magnets prepared by DMPAM can result in the higher H cj and lower knee-point coercivity (H k) compared with that by SAM. Furthermore, for Magnet II, the abnormal grain growth contributes to a better grain alignment and smaller distribution coefficient (σ) defined as the degree of grain alignment, which will enforce a higher tendency of the H cj decreasing and H k increasing. The expression of their normalized coercivity h(σ) is deduced by combining Gao’s starting field model with Kronmüller’s nucleation mechanism. Based on the overall h(σ) ~ σ curve, the best desirable h(σ) value is calculated when σ  =  0.09. Theoretically, for Magnet III, the resultant larger σ should be attributed to the more uniform grain alignment. In addition, the deviations of grain size distributions on the c-plane become more remarkable with more MM concentrates, which can be presented by SEM images. Meanwhile, by means of the pole figures, it is also verified that the grain alignment distribution becomes much more diverse with x increasing. Therefore, it can be predicted whether the grain alignment distribution is significant for H k and H cj of (MM x Nd1-x )-Fe-B sintered magnets (x  ≠  0.6) prepared by SAM/DMPAM or not.

  1. MODELING OF TRACTION SYNCHRONOUS PERMANENT MAGNET MOTOR MODES

    Directory of Open Access Journals (Sweden)

    Y.N. Vas’kovsky

    2013-10-01

    Full Text Available A mathematical model of electromagnetic field for simulating operational modes of traction synchronous motors with permanent magnets intended for electric vehicles is developed. The mathematical model takes into account real-time rotor rotation and allows calculating and analyzing the motor basic running characteristics as time functions.

  2. Nonlinear control of permanent magnet synchronous motor driving a ...

    African Journals Online (AJOL)

    This paper presents a non-linear control of permanent magnet synchronous motor (PMSM) fed by a PWM voltage source inverter. To improve the performance of this control technique, the input-output linearization technique is proposed for a system driving a mechanical load with two masses. In order to ensure a steady ...

  3. Resonant inverter supplied Interior Permanent Magnet (IPM) motor ...

    African Journals Online (AJOL)

    In this paper, rotor position in relation to the resonant frequency component current in the stator winding of DC-voltage link resonant inverter supplied Interior Permanent Magnet (IPM) motor has been developed. Six reference frames are used to relate the rotor position angle to the resonant frequency component current ...

  4. Force measurements on a shielded coreless linear permanent magnet motor

    NARCIS (Netherlands)

    Pluk, K.J.W.; Jansen, J.W.; Lomonova, E.A.

    2014-01-01

    This paper compares force measurements on a shielded coreless linear permanent magnet motor with 2-D models. A 2-D semianalytical modeling method is applied, which is based on Fourier modeling and includes force calculations. The semianalytical modeling correctly predicts the behavior found in the

  5. Failure Diagnosis for Demagnetization in Interior Permanent Magnet Synchronous Motors

    Directory of Open Access Journals (Sweden)

    Takeo Ishikawa

    2017-01-01

    Full Text Available Since a high degree of reliability is necessary for permanent magnet synchronous motors, the detection of a precursor for the demagnetization of permanent magnets is very important. This paper investigates the diagnosis of very slight PM demagnetization. The permanent magnet volume is altered so as to mimic the effect of demagnetization. This paper investigates the influence of demagnetization by using several methods: the 3D finite element analysis (FEA of the motor, the measurement of high-frequency impedance, and the measurement and FEA of the stator voltage and current under vector control. We have obtained the following results. The back-EMF is proportional to permanent magnet volume, and there is no difference in the demagnetization in the radial direction and in the axial direction. Even harmonics and subharmonics of flux density at the teeth tip could be useful for diagnosis if a search coil is installed there. The relatively low frequency resistance at the d-axis position is useful for diagnosis. Under vector control, the stator voltage is useful except in an intermediate torque range, and the intermediate torque is expressed by a simple equation.

  6. Comparative analysis of various methods for modelling permanent magnet machines

    NARCIS (Netherlands)

    Ramakrishnan, K.; Curti, M.; Zarko, D.; Mastinu, G.; Paulides, J.J.H.; Lomonova, E.A.

    2017-01-01

    In this paper, six different modelling methods for permanent magnet (PM) electric machines are compared in terms of their computational complexity and accuracy. The methods are based primarily on conformal mapping, mode matching, and harmonic modelling. In the case of conformal mapping, slotted air

  7. Slotless brushless permanent magnet motor and winding topologies

    International Nuclear Information System (INIS)

    Chen, Y.S.; Zhu, Z.Q.; Howe, D.; Hu, G.F.

    1998-01-01

    In the paper, the merits of alternative slotless brushless permanent magnet motor and winding topologies are investigated, using 2-D analytical models embodied with CAD design software. The design optimisation of both internal and external rotor motors, with and without stator back-iron, and with either overlapping or non-overlapping winding, is considered. (orig.)

  8. Nanocomposite permanent magnetic materials Nd-Fe-B type: The influence of nanocomposite on magnetic properties

    Directory of Open Access Journals (Sweden)

    Talijan Nadežda M.

    2005-01-01

    Full Text Available The influence on the magnetic properties of nanocristalline ribbons and powders has character of microstructure, between others – the grain size volume of hard and soft magnetic phases and their distribution. Magnetic properties of ribbons and powders depend mainly on their chemical composition and parameters of their heat treatment [1]. Technology of magnets from nanocristalline ribbon consists of the following process: preparing the Nd-Fe- B alloy, preparing the ribbon, powdering of the ribbon, heat treatment of the powder and finally preparing the magnets. Nanocomposite permanent magnet materials based on Nd-Fe- B alloy with Nd low content are a new type of permanent magnetic material. The microstructure of this nanocomposite permanent magnet is composed of a mixture of magnetically soft and hard phases which provide so called exchange coupling effect.

  9. Axial magnetic field produced by axially and radially magnetized permanent rings

    International Nuclear Information System (INIS)

    Peng, Q.L.; McMurry, S.M.; Coey, J.M.D.

    2004-01-01

    Axial magnetic fields produced by axially and radially magnetized permanent magnet rings were studied. First, the axial magnetic field produced by a current loop is introduced, from which the axial field generated by an infinitely thin solenoid and by an infinitely thin current disk can be derived. Then the axial fields produced by axially and by radially magnetized permanent magnet rings can be obtained. An analytic formula for the axial fields produced by two axially magnetized rings is given. A permanent magnet with a high axial gradient field is fabricated, the measured results agree with the theoretical calculation very well. As an example, the axial periodic field produced by an arrangement of alternating axially and radially magnetized rings has been discussed

  10. Cobalt-Free Permanent Magnet Alloys.

    Science.gov (United States)

    1984-10-01

    ThC Ferrites (Zn, Mn. Cu, Fe)O A12O. Al TiC Kaolin Al203.Si02-Fe2O3 Fe2O3 Li B4C Spodumene LiAI (SiOs) 2 ThO2 Ni UC Rhodonite NtnO. SiO2 MnOs Fe TaC...minutes. X-ray diffraction pattern indicated the presence of magnetic T phase. Hysteresis loop was measured on the heat treated powder dispersed in wax...fmgei * T phse Hysersi loo was mesue on the. heat - treated ,--". " powder dispersed in wax... The’ result wer as"- follows: • , " • "• . I TABLE 6

  11. Performance Comparison of Permanent Magnet Linear Actuators of Different Mover Types

    DEFF Research Database (Denmark)

    Ritchie, Ewen; Hinov, K.; Yatchev, I.

    2006-01-01

    A comparative study of permanent magnet linear actuators with different location of the permanent magnet is reported. Three mover types are considered - soft magnetic mover, permanent magnet mover and hybrid mover. Force-stroke characteristics are obtained with the help of finite element models...

  12. Calculation and Analysis of Permanent Magnet Eddy Current Loss Fault with Magnet Segmentation

    Directory of Open Access Journals (Sweden)

    Bing Li

    2016-01-01

    Full Text Available This paper investigates the problem of calculating and analyzing the effect of the permanent magnet eddy current loss fault due to magnet segmentation. Taking an interior permanent magnet synchronous motor with inverter supplied as an example, the rated power of motor was 2.2 kW. Three-dimensional finite-element model was firstly established based on finite-element software. Then, the model mesh and boundary conditions were handled specially; permanent magnet eddy current loss fault was calculated and analyzed theoretically with magnet segmentation from space harmonic and time harmonic, respectively. Finally, calculation results were compared and explained. A useful conclusion for permanent magnet synchronous motor design has been obtained.

  13. Rotating permanent magnet excitation for blood flow measurement.

    Science.gov (United States)

    Nair, Sarath S; Vinodkumar, V; Sreedevi, V; Nagesh, D S

    2015-11-01

    A compact, portable and improved blood flow measurement system for an extracorporeal circuit having a rotating permanent magnetic excitation scheme is described in this paper. The system consists of a set of permanent magnets rotating near blood or any conductive fluid to create high-intensity alternating magnetic field in it and inducing a sinusoidal varying voltage across the column of fluid. The induced voltage signal is acquired, conditioned and processed to determine its flow rate. Performance analysis shows that a sensitivity of more than 250 mV/lpm can be obtained, which is more than five times higher than conventional flow measurement systems. Choice of rotating permanent magnet instead of an electromagnetic core generates alternate magnetic field of smooth sinusoidal nature which in turn reduces switching and interference noises. These results in reduction in complex electronic circuitry required for processing the signal to a great extent and enable the flow measuring device to be much less costlier, portable and light weight. The signal remains steady even with changes in environmental conditions and has an accuracy of greater than 95%. This paper also describes the construction details of the prototype, the factors affecting sensitivity and detailed performance analysis at various operating conditions.

  14. Wind turbine integrated multipole permanent magnet generator (PMG)

    Energy Technology Data Exchange (ETDEWEB)

    Vilsboell, N.; Pinegin, A.; Goussarov, D.

    1996-01-01

    Designed permanent magnet generator (PMG - 20 kW) possesses a number of advantages: it makes possible to replace gearbox, the generator and possibly the hub of the wind turbine by combining wind rotor with external rotor of the generator; use of rare earth magnets Nd-Fe-B allows to reduce mass and dimensions of the generator; use of the PMG for wind turbines increases the reliability of the construction during the life time, comparing to the conventional design (gearbox, asynchronous generator). The test of the PMG -20 kW informs that design method, developed for calculation of multipole permanent magnet generators is correct in general and meets engineering requirements. The calculation uncertainty of the magnetic system and output characteristics does not exceed 2-3%. The test shows, that the maximum efficiency of the PGM - 20 kW with full load can be achieved as high as 90-91.5% and excels the efficiency of the traditional system `generator-gearbox` by 4-5.5%. Designing permanent magnet generator, it is recommended to take into account voltage stabilization (capacitance). Efficiency is expected to be higher, mass and production cost of the generator can be reduced by 25-30%. The frequency converter shall be used not only for control of rotational speed, but also to obtain sinusoidal capacitive current on the generator side. For PMG - 20 kW the angle between voltage and current should be within the range 0-23%. (au)

  15. Pure-type superconducting permanent-magnet undulator.

    Science.gov (United States)

    Tanaka, Takashi; Tsuru, Rieko; Kitamura, Hideo

    2005-07-01

    A novel synchrotron radiation source is proposed that utilizes bulk-type high-temperature superconductors (HTSCs) as permanent magnets (PMs) by in situ magnetization. Arrays of HTSC blocks magnetized by external magnetic fields are placed below and above the electron path instead of conventional PMs, generating a periodic magnetic field with an offset. Two methods are presented to magnetize the HTSCs and eliminate the field offset, enabling the HTSC arrays to work as a synchrotron radiation source. An analytical formula to calculate the peak field achieved in a device based on this scheme is derived in a two-dimensional form for comparison with synchrotron radiation sources using conventional PMs. Experiments were performed to demonstrate the principle of the proposed scheme and the results have been found to be very promising.

  16. A review of radiation-induced demagnetization of permanent magnets

    Science.gov (United States)

    Samin, Adib J.

    2018-05-01

    Radiation-induced demagnetization of permanent magnets is important for a number of applications including space missions, particle accelerators and robots designed to carry out rescue missions at nuclear accidents where magnet failure can lead to serious consequences. This topic has been studied by several investigators over the past three decades and in this work, a review of the available literature is conducted and some general conclusions and trends are presented. In short, it can be gleaned that magnetism loss is dependent on the type of radiation, the energy of the incoming particle and the overall dose or fluence. Furthermore, magnetism loss also shows a dependence on the type of the irradiated magnet, the coercivity of the magnet, the demagnetizing field and the temperature of irradiation.

  17. Investigation Procedure of Magnetic Performances of NdFeB Permanent Magnets

    DEFF Research Database (Denmark)

    Calin, Marius-Daniel; Helerea, Elena; Ritchie, Ewen

    2011-01-01

    The permanent magnet applications based on carbon steel magnets, hard ferrites and AlNiCo magnets classes are renewed with new classes of advanced magnetic materials based on rare earth elements, the Sm-Co and NdFeB types. Performance increase of the hard magnetic materials and their use in speci......The permanent magnet applications based on carbon steel magnets, hard ferrites and AlNiCo magnets classes are renewed with new classes of advanced magnetic materials based on rare earth elements, the Sm-Co and NdFeB types. Performance increase of the hard magnetic materials and their use...... in specific applications impose also great advances in the field of magnetic measurement. New researches need to be validated in order to investigate the NdFeB permanent magnets performances, including their stability under different thermal operational regimes. In this paper a specific investigation...... procedure of magnetic performances of NdFeB permanent magnets in correlation with the range of operating temperature is proposed based on modern hysteresisgraph method and impulse magnetization technique....

  18. Magnetic field shimming of a permanent magnet using a combination of pieces of permanent magnets and a single-channel shim coil for skeletal age assessment of children.

    Science.gov (United States)

    Terada, Y; Kono, S; Ishizawa, K; Inamura, S; Uchiumi, T; Tamada, D; Kose, K

    2013-05-01

    We adopted a combination of pieces of permanent magnets and a single-channel (SC) shim coil to shim the magnetic field in a magnetic resonance imaging system dedicated for skeletal age assessment of children. The target magnet was a 0.3-T open and compact permanent magnet tailored to the hand imaging of young children. The homogeneity of the magnetic field was first improved by shimming using pieces of permanent magnets. The residual local inhomogeneity was then compensated for by shimming using the SC shim coil. The effectiveness of the shimming was measured by imaging the left hands of human subjects and evaluating the image quality. The magnetic resonance images for the child subject clearly visualized anatomical structures of all bones necessary for skeletal age assessment, demonstrating the usefulness of combined shimming. Copyright © 2013 Elsevier Inc. All rights reserved.

  19. Samarium-cobalt-copper-iron-titanium permanent magnets

    International Nuclear Information System (INIS)

    Inomata, K.; Yamada, M.

    1980-01-01

    A permanent magnet, which comprises a composition containing a Sm-Co compound and consisting essentially of 23 to 30 wt.% of Sm, 0.2 to 1.5 wt.% Ti, 9 to 13 wt., Cu, 3 to 12 wt.% Fe and the balance Co, said magnet having a residual flux density (Br) of about 10 (kG), a coercive force (IC) of about 8 (KOe) and a maximum energy product (BH max) of about 25 (MGOe), having the aforesaid magnetic properties without the necessity of an ageing treatment

  20. Forces between arrays of permanent magnets of basic geometric shapes

    Czech Academy of Sciences Publication Activity Database

    Vokoun, David; Beleggia, M.

    2014-01-01

    Roč. 350, JAN (2014), s. 174-178 ISSN 0304-8853 R&D Projects: GA ČR(CZ) GAP107/11/0391; GA MŠk(CZ) LM2011026 Institutional support: RVO:68378271 Keywords : permanent magnet * cylindrical magnet * attraction force * magnetostatic interaction Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.970, year: 2014 http://ac.els-cdn.com/S0304885313006732/1-s2.0-S0304885313006732-main.pdf?_tid=f6840b24-5115-11e3-9237-00000aab0f6b&acdnat=1384864232_323ac87712560a07

  1. Stabilization of magnet assemblies of permanent magnet sodium flowmeters used in fast breeder reactors

    Energy Technology Data Exchange (ETDEWEB)

    Rajan, K.K., E-mail: kkrajan@igcar.gov.in; Vijayakumar, G.

    2014-08-15

    Highlights: • Stabilization procedure for ALNICO-5 permanent magnet material is evolved. • Effect of time and temperature on ALNICO-5 assembly is determined. • Suitability of ALNICO-5 flowmeters at high temperatures is established. • Temperature coefficient of flux density is determined. - Abstract: Permanent magnet flow meters (PMFMs) are used to measure the sodium flow in sodium cooled Fast Breeder Reactor Circuits. Prototype fast breeder reactor (PFBR) which is under construction at Kalpakkam is a 500 MWe, sodium cooled, pool type reactor. Sodium flow measurement in various loops of the reactor is of prime importance from operational and safety point of view. To measure the flow of electrically conducting liquid sodium, in primary and secondary circuit pipe lines of PFBR, permanent magnet flow meters are used. PMFM is a non-invasive device, which works on the principle of generation of motional EMF by magnetic forces exerted on the charges in a moving conductor. Flowmeters of different pipe sizes ranging from 10 mm to 200 mm pipe diameter are required for PFBR. Long term performance of the flowmeters mainly depends on stability of permanent magnets used in flowmeters to generate constant magnetic field in stainless steel (SS) pipes. This paper describes the effects of time and temperature on permanent magnet assemblies made of ALNICO-V used in PFBR flowmeters. The stabilization methodology for ALNICO-V permanent magnet assemblies is evolved and established. Loss of magnetic field strength with respect to time and temperatures is determined by experiments and found negligible.

  2. Numerical simulation of magnetic convection ferrofluid flow in a permanent magnet-inserted cavity

    Science.gov (United States)

    Ashouri, Majid; Behshad Shafii, Mohammad

    2017-11-01

    The magnetic convection heat transfer in an obstructed two-dimensional square cavity is investigated numerically. The walls of the cavity are heated with different constant temperatures at two sides, and isolated at two other sides. The cavity is filled with a high Prandtl number ferrofluid. The convective force is induced by a magnetic field gradient of a thermally insulated square permanent magnet located at the center of the cavity. The results are presented in the forms of streamlines, isotherms, and Nusselt number for various values of magnetic Rayleigh numbers and permanent magnet size. Two major circulations are generated in the cavity, clockwise flow in the upper half and counterclockwise in the lower half. In addition, strong circulations are observed around the edges of the permanent magnet surface. The strength of the circulations increase monotonically with the magnetic Rayleigh number. The circulations also increase with the permanent magnet size, but eventually, are suppressed for larger sizes. It is found that there is an optimum size for the permanent magnet due to the contrary effects of the increase in magnetic force and the increase in flow resistance by increasing the size. By increasing the magnetic Rayleigh number or isothermal walls temperature ratio, the heat transfer rate increases.

  3. Magnetic field computations of the magnetic circuits with permanent magnets by infinite element method

    International Nuclear Information System (INIS)

    Hahn, Song Yop

    1985-01-01

    A method employing infinite elements is described for the magnetic field computations of the magnetic circuits with permanent magnet. The system stiffness matrix is derived by a variational approach, while the interfacial boundary conditions between the finite element regions and the infinite element regions are dealt with using collocation method. The proposed method is applied to a simple linear problems, and the numerical results are compared with those of the standard finite element method and the analytic solutions. It is observed that the proposed method gives more accurate results than those of the standard finite element method under the same computing efforts. (Author)

  4. Hydrogen Decrepitation Press-Less Process Recycling of NdFeB sintered magnets

    DEFF Research Database (Denmark)

    Xia, Manlong; Abrahamsen, Asger Bech; Bahl, Christian

    2017-01-01

    A Hydrogen Decrepitation Press-Less Process (HD-PLP) recycling method for recycling of anisotropic NdFeB magnets is demonstrated. The method combines hydrogen decrepitation (HD) disintegration of the initial magnet, powder sieving and the Press-Less Process (PLP), where hydride powder is sintered...

  5. High-throughput search for new permanent magnet materials.

    Science.gov (United States)

    Goll, D; Loeffler, R; Herbst, J; Karimi, R; Schneider, G

    2014-02-12

    The currently highest-performance Fe-Nd-B magnets show limited cost-effectiveness and lifetime due to their rare-earth (RE) content. The demand for novel hard magnetic phases with more widely available RE metals, reduced RE content or, even better, completely free of RE metals is therefore tremendous. The chances are that such materials still exist given the large number of as yet unexplored alloy systems. To discover such phases, an elaborate concept is necessary which can restrict and prioritize the search field while making use of efficient synthesis and analysis methods. It is shown that an efficient synthesis of new phases using heterogeneous non-equilibrium diffusion couples and reaction sintering is possible. Quantitative microstructure analysis of the domain pattern of the hard magnetic phases can be used to estimate the intrinsic magnetic parameters (saturation polarization from the domain contrast, anisotropy constant from the domain width, Curie temperature from the temperature dependence of the domain contrast). The probability of detecting TM-rich phases for a given system is high, therefore the approach enables one to scan through even higher component systems with one single sample. The visualization of newly occurring hard magnetic phases via their typical domain structure and the correlation existing between domain structure and intrinsic magnetic properties allows an evaluation of the industrial relevance of these novel phases.

  6. Novel mechanisms for solid-state processing and grain growth with microstructure alignment in alnico-8 based permanent magnets

    Science.gov (United States)

    Kassen, Aaron G.; White, Emma M. H.; Hu, Liangfa; Tang, Wei; Zhou, Lin; Kramer, Matthew J.; Anderson, Iver E.

    2018-05-01

    An estimated 750,000 new hybrid electric and plug-in battery vehicles, most with permanent magnet synchronous alternating current (PMAC) drive motors, took to the road in 2016 alone. Accompanied by 40% year over year growth in the EV market significant challenges exist in producing large quantities of permanent magnets (on the order of tens of millions) for reliable, low-cost traction motors [IE Agency, Energy Technology Perspectives (2017)]. Since the rare earth permanent magnet (REPM) market is essentially 100% net import reliant in the United States and has proven to have an unstable cost and supply structure in recent years, a replacement RE-free PM material must be designed or selected, fully developed, and implemented. Alnico, with its high saturation magnetization and excellent thermal stability, appears to be uniquely suited for this task. Further, while alnico typically has been considered a relatively low coercivity hard magnet, strides have been made to increase the coercivity to levels suitable for traction drive motors [W Tang, IEEE Trans. Magn., 51 (2015)]. If a simple non-cast approach for achieving near [001] easy axis grain aligned permanent magnets can be found, this would allow mass-produced final-shape anisotropic high energy product magnets suitable for usage in compact high RPM rotor designs. Therefore, a powder metallurgical approach is being explored that uses classic compression molding with "de-bind and sinter" methods, where a novel applied uniaxial loading, and an applied magnetic field may create final-shape magnets with highly textured resulting microstructures by two different mechanisms. Results indicate a positive correlation between applied uniaxial load and resulting texture (Fig. 1), along with benefits from using an applied magnetic field for improved texture, as well. The apparent mechanisms and resulting properties will be described using closed loop hysteresisgraph measurements, EBSD orientation mapping, and high

  7. On the motion of the field of a permanent magnet

    Energy Technology Data Exchange (ETDEWEB)

    Leus, Vladimir [Sobolev Institute of Mathematics, Novosibirsk (Russian Federation); Taylor, Stephen, E-mail: s.taylor@liv.ac.uk [Department of Electrical Engineering and Electronics, University of Liverpool, Liverpool L69 3GJ (United Kingdom)

    2011-09-15

    A description is given of a series of recent experiments using a rotating magnetic circuit comprising a permanent magnet ring and yoke, and a stationary conductor in the air gap between the ring and yoke. The EMF induced in this case cannot be described by a simple application of Faraday's flux law. This is because the magnetic flux in the air gap and the area of the gap both remain constant. The experimental results are best explained by the fact that the magnetic field itself rotates with the rotating magnet. This is controversial in the scientific and educational literature, as shown by citations from various authors (e.g. Feynman, Tamm and Landau all disagree, and with each other). However, these experiments, which may be readily reproduced, do in fact settle the question.

  8. Performance of an Adjustable Strength Permanent Magnet Quadrupole

    CERN Document Server

    Gottschalk, Stephen C; Kangas, Kenneth; Spencer, Cherrill M; Volk, James T

    2005-01-01

    An adjustable strength permanent magnet quadrupole suitable for use in Next Linear Collider has been built and tested. The pole length is 42cm, aperture diameter 13mm, peak pole tip strength 1.03Tesla and peak integrated gradient * length (GL) is 68.7 Tesla. This paper describes measurements of strength, magnetic centerline and field quality made using an air bearing rotating coil system. The magnetic centerline stability during -20% strength adjustment proposed for beam based alignment was < 0.2 microns. Strength hysteresis was negligible. Thermal expansion of quadrupole and measurement parts caused a repeatable and easily compensated change in the vertical magnetic centerline. Calibration procedures as well as centerline measurements made over a wider tuning range of 100% to 20% in strength useful for a wide range of applications will be described. The impact of eddy currents in the steel poles on the magnetic field during strength adjustments will be reported.

  9. Quantum Hall effect in epitaxial graphene with permanent magnets.

    Science.gov (United States)

    Parmentier, F D; Cazimajou, T; Sekine, Y; Hibino, H; Irie, H; Glattli, D C; Kumada, N; Roulleau, P

    2016-12-06

    We have observed the well-kown quantum Hall effect (QHE) in epitaxial graphene grown on silicon carbide (SiC) by using, for the first time, only commercial NdFeB permanent magnets at low temperature. The relatively large and homogeneous magnetic field generated by the magnets, together with the high quality of the epitaxial graphene films, enables the formation of well-developed quantum Hall states at Landau level filling factors v = ±2, commonly observed with superconducting electro-magnets. Furthermore, the chirality of the QHE edge channels can be changed by a top gate. These results demonstrate that basic QHE physics are experimentally accessible in graphene for a fraction of the price of conventional setups using superconducting magnets, which greatly increases the potential of the QHE in graphene for research and applications.

  10. Quantum Hall effect in epitaxial graphene with permanent magnets

    Science.gov (United States)

    Parmentier, F. D.; Cazimajou, T.; Sekine, Y.; Hibino, H.; Irie, H.; Glattli, D. C.; Kumada, N.; Roulleau, P.

    2016-12-01

    We have observed the well-kown quantum Hall effect (QHE) in epitaxial graphene grown on silicon carbide (SiC) by using, for the first time, only commercial NdFeB permanent magnets at low temperature. The relatively large and homogeneous magnetic field generated by the magnets, together with the high quality of the epitaxial graphene films, enables the formation of well-developed quantum Hall states at Landau level filling factors v = ±2, commonly observed with superconducting electro-magnets. Furthermore, the chirality of the QHE edge channels can be changed by a top gate. These results demonstrate that basic QHE physics are experimentally accessible in graphene for a fraction of the price of conventional setups using superconducting magnets, which greatly increases the potential of the QHE in graphene for research and applications.

  11. Method for forming permanent magnets with different polarities for use in microelectromechanical devices

    Science.gov (United States)

    Roesler, Alexander W [Tijeras, NM; Christenson, Todd R [Albuquerque, NM

    2007-04-24

    Methods are provided for forming a plurality of permanent magnets with two different north-south magnetic pole alignments for use in microelectromechanical (MEM) devices. These methods are based on initially magnetizing the permanent magnets all in the same direction, and then utilizing a combination of heating and a magnetic field to switch the polarity of a portion of the permanent magnets while not switching the remaining permanent magnets. The permanent magnets, in some instances, can all have the same rare-earth composition (e.g. NdFeB) or can be formed of two different rare-earth materials (e.g. NdFeB and SmCo). The methods can be used to form a plurality of permanent magnets side-by-side on or within a substrate with an alternating polarity, or to form a two-dimensional array of permanent magnets in which the polarity of every other row of the array is alternated.

  12. The electromagnetic design of a permanent magnet based separator

    International Nuclear Information System (INIS)

    Nedelcu, S.

    2002-08-01

    The aim of this work was to design a permanent magnet based device that can selectively transport paramagnetic particles. Using specialised electromagnetic design software various arrangements of permanent magnets have been investigated. Each test geometry had to be constructively simple and able to produce highly non-uniform magnetic fields before being considered further in any more detail. The main parameter to indicate that the test geometry might be a suitable device has been ascribed to the ratio η between the highest (ON) and lowest (OFF) magnetic fields that were measured. A linear arrangement of permanent magnets has been considered first. This device produced a ratio η ∼ 2. Further, the cylindrical and the tubular arrangements may be considered as substantial improvements over the first geometry. The OFF magnetic fields have been substantially reduced by the method of magnetic shielding. Intensive research and modelling has been spent on addressing the problem of finding the optimal geometry for such arrangements. An experimental system has been also built, and the experimental values were compared against the theory. However, the results produced evidence that the manufacturing of any improved geometry (an estimated η ∼ 100) in this direction might be very difficult, for the tolerances involved were very strict. The disk arrangement was the latest device to be investigated. Particularly, a magnetic dipole model developed earlier for the ring arrangement suggested the way in which to arrange the magnets in the ON position. Moreover, the use of the magnetic symmetry of the device forced the OFF magnetic fields to negligible values. Detailed computer simulations of the dynamics of the particles in the applied magnetic field of the tubular and disk arrangements have been earned out. The adopted models could show realistic phenomena, e.g. particle clustering, chaining, block movement, etc. The separation efficiency proved to be nearly 100%. For the

  13. System and method for preventing stator permanent magnet demagnetization during vacuum pressure impregnation

    Science.gov (United States)

    Raminosoa, Tsarafidy; Alexander, James Pellegrino; EL-Refaie, Ayman Mohamed Fawzi

    2017-06-06

    A permanent magnet electrical machine includes a stator having conductive windings wound thereon and one or more permanent magnets embedded in the stator. A magnetic keeper element is positioned on the stator so as to form a magnetic flux path with the permanent magnets, with the magnetic keeper element closing the magnetic flux path of the permanent magnets by providing a low reluctance flux path to magnetic flux generated by the permanent magnets. A vacuum pressure impregnation (VPI) process is performed on the stator to increase a thermal conductivity of the windings, with the VPI process including a curing step that is performed at a selected temperature. The magnetic keeper element sets an operating point of the permanent magnets to an internal flux density level above a demagnetization threshold associated with the selected temperature at which the curing step is performed.

  14. Permanent magnet finger-size scanning electron microscope columns

    Energy Technology Data Exchange (ETDEWEB)

    Nelliyan, K., E-mail: elenk@nus.edu.sg [Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117576 (Singapore); Khursheed, A. [Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117576 (Singapore)

    2011-07-21

    This paper presents permanent magnet scanning electron microscope (SEM) designs for both tungsten and field emission guns. Each column makes use of permanent magnet technology and operates at a fixed primary beam voltage. A prototype column operating at a beam voltage of 15 kV was made and tested inside the specimen chamber of a conventional SEM. A small electrostatic stigmator unit and dedicated scanning coils were integrated into the column. The scan coils were wound directly around the objective lens iron core in order to reduce its size. Preliminary experimental images of a test grid specimen were obtained through the prototype finger-size column, demonstrating that it is in principle feasible.

  15. A New Torque Control System of Permanent Magnet Synchronous Motor

    Directory of Open Access Journals (Sweden)

    Evstratov Andrey

    2017-01-01

    Full Text Available The article describes a new approach to control of permanent magnet synchronous motor drive based on the analysis of the electromechanical transformation. The proposed control system provides quick response and low ripple of the motor torque and flux. To synthesis this control system, the authors put the electromagnetic torque and the modulus of stator flux vector as controlled values and use the Lyapunov’s second method. In addition, the stator voltage constriction and ability of low-pass filtration are taken into account. The investigation of the proposed control system has carried out with the simulation and the experimental research which have confirmed that the proposed control system correspond to all above-mentioned control tasks and the permanent magnet synchronous motor controlled under this system may be recommended to use in robotics.

  16. Permanent magnet finger-size scanning electron microscope columns

    International Nuclear Information System (INIS)

    Nelliyan, K.; Khursheed, A.

    2011-01-01

    This paper presents permanent magnet scanning electron microscope (SEM) designs for both tungsten and field emission guns. Each column makes use of permanent magnet technology and operates at a fixed primary beam voltage. A prototype column operating at a beam voltage of 15 kV was made and tested inside the specimen chamber of a conventional SEM. A small electrostatic stigmator unit and dedicated scanning coils were integrated into the column. The scan coils were wound directly around the objective lens iron core in order to reduce its size. Preliminary experimental images of a test grid specimen were obtained through the prototype finger-size column, demonstrating that it is in principle feasible.

  17. Photovoltaic-wind hybrid system for permanent magnet DC motor

    Science.gov (United States)

    Nasir, M. N. M.; Lada, M. Y.; Baharom, M. F.; Jaafar, H. I.; Ramani, A. N.; Sulaima, M. F.

    2015-05-01

    Hybrid system of Photovoltaic (PV) - Wind turbine (WT) generation has more advantages and reliable compared to PV or wind turbine system alone. The aim of this paper is to model and design hybrid system of PV-WT supplying 100W permanent-magnet dc motor. To achieve the objective, both of PV and WT are connected to converter in order to get the same source of DC supply. Then both sources were combined and straightly connected to 100W permanent magnet dc motor. All the works in this paper is only applied in circuit simulator by using Matlab Simulink. The output produced from each converter is expected to be suit to the motor specification. The output produced from each renewable energy system is as expected to be high as it can support the motor if one of them is breakdown

  18. FUZZY FAULT DETECTION FOR PERMANENT MAGNET SYNCHRONOUS GENERATOR

    Directory of Open Access Journals (Sweden)

    N. Selvaganesan

    2011-07-01

    Full Text Available Faults in engineering systems are difficult to avoid and may result in serious consequences. Effective fault detection and diagnosis can improve system reliability and avoid expensive maintenance. In this paper fuzzy system based fault detection scheme for permanent magnet synchronous generator is proposed. The sequence current components like positive and negative sequence currents are used as fault indicators and given as inputs to fuzzy fault detector. Also, the fuzzy inference system is created and rule base is evaluated, relating the sequence current component to the type of faults. These rules are fired for specific changes in sequence current component and the faults are detected. The feasibility of the proposed scheme for permanent magnet synchronous generator is demonstrated for different types of fault under various operating conditions using MATLAB/Simulink.

  19. Disc rotors with permanent magnets for brushless DC motor

    Science.gov (United States)

    Hawsey, Robert A.; Bailey, J. Milton

    1992-01-01

    A brushless dc permanent magnet motor drives an autonomous underwater vehe. In one embodiment, the motor comprises four substantially flat stators in stacked relationship, with pairs of the stators axially spaced, each of the stators comprising a tape-wound stator coil, and first and second substantially flat rotors disposed between the spaced pairs of stators. Each of the rotors includes an annular array of permanent magnets embedded therein. A first shaft is connected to the first rotor and a second, concentric shaft is connected to the second rotor, and a drive unit causes rotation of the two shafts in opposite directions. The second shaft comprises a hollow tube having a central bore in which the first shaft is disposed. Two different sets of bearings support the first and second shafts. In another embodiment, the motor comprises two ironless stators and pairs of rotors mounted on opposite sides of the stators and driven by counterrotating shafts.

  20. New Cogging Torque Reduction Methods for Permanent Magnet Machine

    Science.gov (United States)

    Bahrim, F. S.; Sulaiman, E.; Kumar, R.; Jusoh, L. I.

    2017-08-01

    Permanent magnet type motors (PMs) especially permanent magnet synchronous motor (PMSM) are expanding its limbs in industrial application system and widely used in various applications. The key features of this machine include high power and torque density, extending speed range, high efficiency, better dynamic performance and good flux-weakening capability. Nevertheless, high in cogging torque, which may cause noise and vibration, is one of the threat of the machine performance. Therefore, with the aid of 3-D finite element analysis (FEA) and simulation using JMAG Designer, this paper proposed new method for cogging torque reduction. Based on the simulation, methods of combining the skewing with radial pole pairing method and skewing with axial pole pairing method reduces the cogging torque effect up to 71.86% and 65.69% simultaneously.

  1. Water flow patterns induced by bridge oscillation of magnetic fluid between two permanent magnets subjected to alternating magnetic field

    International Nuclear Information System (INIS)

    Sudo, Seiichi; Yamamoto, Kazuki; Ishimoto, Yukitaka; Nix, Stephanie

    2017-01-01

    This paper describes the characteristics of water flow induced by the bridge oscillation of magnetic fluid between two permanent magnets subject to an external alternating magnetic field. The magnetic fluid bridge is formed in the space between a pair of identical coaxial cylindrical permanent magnets submerged in water. The direction of alternating magnetic field is parallel /antiparallel to the magnetic field produced by two permanent magnets. The magnetic fluid bridge responds to the external alternating magnetic field with harmonic oscillation. The oscillation of magnetic fluid bridge generates water flow around the bridge. Water flow is visualized using a thin milk film at the container bottom. Water flows are observed with a high-speed video camera analysis system. The experimental results show that the flow pattern induced by the bridge oscillation depends on the Keulegan–Carpenter number.

  2. Water flow patterns induced by bridge oscillation of magnetic fluid between two permanent magnets subjected to alternating magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Sudo, Seiichi, E-mail: sudo@akita-pu.ac.jp [Faculty of Systems Science and Technology, Akita Prefectural University, Ebinokuchi 84-4, Yurihonjo 015-0055 (Japan); Yamamoto, Kazuki [Graduate School of Engineering, Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai 980-8577 (Japan); Ishimoto, Yukitaka; Nix, Stephanie [Faculty of Systems Science and Technology, Akita Prefectural University, Ebinokuchi 84-4, Yurihonjo 015-0055 (Japan)

    2017-06-01

    This paper describes the characteristics of water flow induced by the bridge oscillation of magnetic fluid between two permanent magnets subject to an external alternating magnetic field. The magnetic fluid bridge is formed in the space between a pair of identical coaxial cylindrical permanent magnets submerged in water. The direction of alternating magnetic field is parallel /antiparallel to the magnetic field produced by two permanent magnets. The magnetic fluid bridge responds to the external alternating magnetic field with harmonic oscillation. The oscillation of magnetic fluid bridge generates water flow around the bridge. Water flow is visualized using a thin milk film at the container bottom. Water flows are observed with a high-speed video camera analysis system. The experimental results show that the flow pattern induced by the bridge oscillation depends on the Keulegan–Carpenter number.

  3. Plasma sprayed Nd-Fe-B permanent magnets

    International Nuclear Information System (INIS)

    Willson, M.; Bauser, S.; Liu, S.; Huang, M.

    2003-01-01

    This study demonstrated that the plasma spray deposition method is an alternative process for producing Nd-Fe-B magnets in addition to the two existing principal processes: the powder metallurgy process for producing sintered Nd-Fe-B magnets and the melt spinning process for bonded Nd-Fe-B magnets. Plasma spray is a potentially better process for producing magnetic parts with complicated shape, large area, thin thickness, small dimension, or unusual geometry. High intrinsic coercivity greater than 15 kOe was readily obtained for Nd 16 Dy 1 Fe 76 B 7 even in the as-deposited condition when the substrate was preheated. The plasma spray process contains only three steps: melting, crushing, and plasma spray, which is much simpler than the powder metallurgy and melt spinning processes. Without preheating the substrate, the coercivity was usually very low (∼0.1 kOe) in the as-deposited condition and it increased to 10 to >15 kOe after anneal. Evidence of magnetocrystalline anisotropy was observed in plasma sprayed Nd 15 Dy 1 Fe 77 B 7 magnets when the substrate was not preheated. It is believed that a crystal texture was developed during the plasma spray as a result of the existence of a temperature gradient in the solidifying melt

  4. Permanent magnet machine with windings having strand transposition

    Science.gov (United States)

    Qu, Ronghai; Jansen, Patrick Lee

    2009-04-21

    This document discusses, among other things, a stator with transposition between the windings or coils. The coils are free from transposition to increase the fill factor of the stator slots. The transposition at the end connections between an inner coil and an outer coil provide transposition to reduce circulating current loss. The increased fill factor reduces further current losses. Such a stator is used in a dual rotor, permanent magnet machine, for example, in a compressor pump, wind turbine gearbox, wind turbine rotor.

  5. Simulation of dynamics of a permanent magnet linear actuator

    DEFF Research Database (Denmark)

    Yatchev, Ivan; Ritchie, Ewen

    2010-01-01

    Comparison of two approaches for the simulation of the dynamic behaviour of a permanent magnet linear actuator is presented. These are full coupled model, where the electromagnetic field, electric circuit and mechanical motion problems are solved simultaneously, and decoupled model, where first...... flexibility when the actuator response is required to be estimated for different external conditions, e.g. external circuit parameters or mechanical loads....

  6. Dynamics and Stability of Permanent-Magnet Synchronous Motor

    OpenAIRE

    He, Ren; Han, Qingzhen

    2017-01-01

    The aim of this article is to explore the dynamic characteristics and stability of the permanent-magnet synchronous motor (PMSM). PMSM equilibrium local stability condition and Hopf  bifurcation condition, pitchfork bifurcation condition, and fold bifurcation condition have been derived by using the Routh-Hurwitz criterion and the bifurcation theory, respectively. Bifurcation curves of the equilibrium with single and double parameters are obtained by continuation method. Numerical simulations...

  7. Forces between a permanent magnet and a soft magnetic plate

    Czech Academy of Sciences Publication Activity Database

    Beleggia, M.; Vokoun, David; DeGraef, M.

    2012-01-01

    Roč. 3, č. 5 (2012), 0500204/1-0500204/4 ISSN 1949-307X R&D Projects: GA ČR GPP108/12/P111 Institutional research plan: CEZ:AV0Z10100520 Keywords : electromagnetics * hard magnetic materials * soft magnetic materials Subject RIV: BM - Solid Matter Physics ; Magnetism http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=6313974

  8. Motor Integrated Permanent Magnet Gear with a Wide Torque-Speed Range

    DEFF Research Database (Denmark)

    Rasmussen, Peter Omand; Matzen, Torben N.; Jahns, T. M.

    2009-01-01

    This paper present a new motor integrated permanent magnet gear with a wide torque-speed range. In the paper a 35 kW permanent magnet motor with a base speed of 4000 rpm and a top speed of 14000 rpm is integrated into a permanent magnetic gear with a gearing ratio of 8.67. The design process...

  9. Permanent magnetic ferrite based power-tunable metamaterials

    Science.gov (United States)

    Zhang, Guanqiao; Lan, Chuwen; Gao, Rui; Zhou, Ji

    2017-08-01

    Power-tunable metamaterials based on barium permanent magnetic ferrite have been proposed and fabricated in this research. Scattering parameter measurements confirm a shift in resonant frequency in correlation to changes in incident electromagnetic power within microwave frequency band. The tunable phenomenon represented by a blue-shift in transmission spectra in the metamaterials array can be attributed to a decrease in saturation magnetization resulting from FMR-induced temperature elevation upon resonant conditions. This power-dependent behavior offers a simple and practical route towards dynamically fine-tunable ferrite metamaterials.

  10. Quasi permanent superconducting magnet of very high field

    Science.gov (United States)

    Ren, Y.; Liu, J.; Weinstein, R.; Chen, I. G.; Parks, D.; Xu, J.; Obot, V.; Foster, C.

    1993-01-01

    We report on persistent field in a quasi-permanent magnet made of high temperature superconductor. The material has an average of 40 percent molar excess of Y, relative to Y1Ba2Cu3O7 and has been irradiated with high energy light ions at 200 MeV. The magnet, which traps 1.52 T at 77.3 K, traps nearly 4 T at 64.5 K. No evidence of giant flux jump or sample cracking was observed.

  11. Superconducting Electric Machine with Permanent Magnets and Bulk HTS Elements

    Science.gov (United States)

    Levin, A. V.; Vasich, P. S.; Dezhin, D. S.; Kovalev, L. K.; Kovalev, K. L.; Poltavets, V. N.; Penkin, V. T.

    Theoretical methods of calculating of two-dimensional magnetic fields, inductive parameters and output characteristics of the new type of high-temperature superconducting (HTS) synchronous motors with a composite rotor are presented. The composite rotor has the structure containing HTS flat elements, permanent magnets and ferromagnetic materials. The developed calculation model takes into account the concentrations and physical properties of these rotor elements. The simulation results of experimental HTS motor with a composite rotor are presented. The application of new type of HTS motor in different constructions of industrial high dynamic drivers is discussed.

  12. Two dimensional model of a permanent magnet spur gear

    DEFF Research Database (Denmark)

    Jørgensen, Frank Thorleif; Andersen, Torben Ole; Rasmussen, Peter Omand

    2005-01-01

    This paper presents calculation and measurement results of a high-performance permanent-magnetic gear. The analyzed permanent-magnetic gear has a gear ratio of 5.5 and is able to deliver 27 N/spl middot/m. The analysis has shown that special attention needs to be paid to the system where the gear...... is to be installed because of a low natural torsion spring constant. The analyzed gear was also constructed in practice in order to validate the analysis and predict the efficiency. The measured torque from the magnetic gear was only 16 N/spl middot/m reduced by the large end-effects. A systematic analysis...... of the loss components in the magnetic gear is also performed in order to figure out why the efficiency for the actual construction was only 81%. A large magnetic loss component originated in the bearings, where an unplanned extra bearing was necessary due to mechanical problems. Without the losses...

  13. Permanent magnet design for magnetic heat pumps using total cost minimization

    Science.gov (United States)

    Teyber, R.; Trevizoli, P. V.; Christiaanse, T. V.; Govindappa, P.; Niknia, I.; Rowe, A.

    2017-11-01

    The active magnetic regenerator (AMR) is an attractive technology for efficient heat pumps and cooling systems. The costs associated with a permanent magnet for near room temperature applications are a central issue which must be solved for broad market implementation. To address this problem, we present a permanent magnet topology optimization to minimize the total cost of cooling using a thermoeconomic cost-rate balance coupled with an AMR model. A genetic algorithm identifies cost-minimizing magnet topologies. For a fixed temperature span of 15 K and 4.2 kg of gadolinium, the optimal magnet configuration provides 3.3 kW of cooling power with a second law efficiency (ηII) of 0.33 using 16.3 kg of permanent magnet material.

  14. Temperature compensation of NdFeB permanent magnets

    International Nuclear Information System (INIS)

    Kim, S.H.; Doose, C.

    1997-01-01

    Permanent magnet blocks of NdFeB have a relatively high maximum energy product. Because of its relatively low Curie temperature, however, NdFeB has a large temperature coefficient for its residual induction. The temperature coefficients of the relative magnetic fields (ΔB/B)/ΔT in the air gap of NdFeB dipole magnets were reduced from -1.1 x 10 -3 /c to less than 2 x 10 -5 /degree C under operating temperatures of ± 6 C. This was achieved passively by using 1.25-mm-thick strips of 30%-Ni-Fe alloy as flux shunts for the NdFeB blocks. The magnets with soft-steel poles and flux-return yokes were assembled and measured in a temperature-controlled environment

  15. Inspired by nature: investigating tetrataenite for permanent magnet applications.

    Science.gov (United States)

    Lewis, L H; Mubarok, A; Poirier, E; Bordeaux, N; Manchanda, P; Kashyap, A; Skomski, R; Goldstein, J; Pinkerton, F E; Mishra, R K; Kubic, R C; Barmak, K

    2014-02-12

    Chemically ordered L10-type FeNi, also known as tetrataenite, is under investigation as a rare-earth-free advanced permanent magnet. Correlations between crystal structure, microstructure and magnetic properties of naturally occurring tetrataenite with a slightly Fe-rich composition (~ Fe55Ni44) obtained from the meteorite NWA 6259 are reported and augmented with computationally derived results. The tetrataenite microstructure exhibits three mutually orthogonal crystallographic variants of the L10 structure that reduce its remanence; nonetheless, even in its highly unoptimized state tetrataenite provides a room-temperature coercivity of 95.5 kA m(-1) (1200 Oe), a Curie temperature of at least 830 K and a largely temperature-independent anisotropy that preliminarily point to a theoretical magnetic energy product exceeding (BH)max = 335 kJ m(-3) (42 MG Oe) and approaching those found in today's best rare-earth-based magnets.

  16. Addressing Criticality in Rare Earth Elements via Permanent Magnets Recycling

    Science.gov (United States)

    Nlebedim, I. C.; King, A. H.

    2018-02-01

    Rare earth elements (REEs) are critical for many advanced technologies and are faced with potential supply disruptions. Recycling of permanent magnets (PMs) can be good sources for REEs which can help minimize global dependence on freshly mined REEs, but PMs are rarely recycled. Recycling of PMs has been discussed with respect to improving REEs resource sustainability. Some challenges to be addressed in order to establish industrially deployable technologies for PMs recycling have also been discussed, including profitability, energy efficiency and environmental impacts. Key considerations for promoting circular economy via PMs recycling is proposed with the focus on deciding the target points in the supply chain at which the recycled products will be inserted. Important technical considerations for recycling different forms of waste PMs, including swarfs, slags, shredded and intact hard disk drives magnets, have been presented. The aspects of circular economy considered include reusing magnets, remanufacturing magnets and recovering of REEs from waste PMs.

  17. Spark-plasma-sintering magnetic field assisted compaction of Co{sub 80}Ni{sub 20} nanowires for anisotropic ferromagnetic bulk materials

    Energy Technology Data Exchange (ETDEWEB)

    Ouar, Nassima; Schoenstein, Frédéric; Mercone, Silvana; Farhat, Samir; Jouini, Noureddine [Laboratoire des Sciences des Procédés et des Matériaux, CNRS, LSPM—UPR 3407, Université Paris 13, Sorbonne-Paris-Cité, 99 Avenue J.-B. Clément, 93430 Villetaneuse (France); Villeroy, Benjamin [Institut de Chimie et des Matériaux Paris Est, CNRS, ICMPE—UMR 7182, Equipe de Chimie Métallurgique des Terres Rares, 2-8 rue Henri Dunant, 94320 Thiais Cedex (France); Leridon, Brigitte [Laboratoire de Physique et d’Étude des Matériaux, LPEM, ESPCI-ParisTech, CNRS, UPMC, 10 rue Vauquelin, F-75231 Paris Cedex 5 (France)

    2013-10-28

    We developed a two-step process showing the way for sintering anisotropic nanostructured bulk ferromagnetic materials. A new reactor has been optimized allowing the synthesis of several grams per batch of nanopowders via a polyol soft chemistry route. The feasibility of the scale-up has been successfully demonstrated for Co{sub 80}Ni{sub 20} nanowires and a massic yield of ∼97% was obtained. The thus obtained nanowires show an average diameter of ∼6 nm and a length of ∼270 nm. A new bottom-up strategy allowed us to compact the powder into a bulk nanostructured system. We used a spark-plasma-sintering technique under uniaxial compression and low temperature assisted by a permanent magnetic field of 1 T. A macroscopic pellet of partially aligned nanowire arrays has been easily obtained. This showed optimized coercive properties along the direction of the magnetic field applied during compaction (i.e., the nanowires' direction)

  18. Development of a cryogenic permanent magnet undulator at the ESRF

    International Nuclear Information System (INIS)

    Kitegi, Ch.

    2008-12-01

    In 2004, at SPring-8, Toru Hara proposed a new concept of undulator with a short period and a high field: the Cryogenic Permanent Magnet Undulator (CPMU). The purpose of this concept is to cool Nd 2 Fe 14 B magnets at 150 K. This cooling allows magnets which have a higher remanence to be used, up to 40% higher than that of the magnets traditionally used in undulators. In order to assess the technological possibility of producing such undulator, a 2 m long undulator with a 18 mm period has been proposed at the ESRF. This piece of work presents the design and the construction of this CPMU at the ESRF. First a magnetic model of the CPMU is introduced; it is based on measurements of the magnetization curve at cryogenic temperature performed at the Louis Neel Laboratory. This model forecasts an increase of the peak field of 8% and of the field integral of 0.2 Gm at around 150 K. A unique magnetic measurement bench has been developed at the ESRF. This bench allows both the in vacuum local field and field integral to be measured. Its design and construction are presented. Finally we have reviewed the measurements at room and cryogenic temperature. These measurements are in agreement with the magnetic model. (author)

  19. Permanent magnetic lattices for ultracold atoms and quantum degenerate gases

    International Nuclear Information System (INIS)

    Ghanbari, Saeed; Kieu, Tien D; Sidorov, Andrei; Hannaford, Peter

    2006-01-01

    We propose the use of periodic arrays of permanent magnetic films for producing magnetic lattices of microtraps for confining, manipulating and controlling small clouds of ultracold atoms and quantum degenerate gases. Using analytical expressions and numerical calculations we show that periodic arrays of magnetic films can produce one-dimensional (1D) and two-dimensional (2D) magnetic lattices with non-zero potential minima, allowing ultracold atoms to be trapped without losses due to spin flips. In particular, we show that two crossed layers of periodic arrays of parallel rectangular magnets plus bias fields, or a single layer of periodic arrays of square-shaped magnets with three different thicknesses plus bias fields, can produce 2D magnetic lattices of microtraps having non-zero potential minima and controllable trap depth. For arrays with micron-scale periodicity, the magnetic microtraps can have very large trap depths (∼0.5 mK for the realistic parameters chosen for the 2D lattice) and very tight confinement

  20. Topology optimization for design of segmented permanent magnet arrays with ferromagnetic materials

    Science.gov (United States)

    Lee, Jaewook; Yoon, Minho; Nomura, Tsuyoshi; Dede, Ercan M.

    2018-03-01

    This paper presents multi-material topology optimization for the co-design of permanent magnet segments and iron material. Specifically, a co-design methodology is proposed to find an optimal border of permanent magnet segments, a pattern of magnetization directions, and an iron shape. A material interpolation scheme is proposed for material property representation among air, permanent magnet, and iron materials. In this scheme, the permanent magnet strength and permeability are controlled by density design variables, and permanent magnet magnetization directions are controlled by angle design variables. In addition, a scheme to penalize intermediate magnetization direction is proposed to achieve segmented permanent magnet arrays with discrete magnetization directions. In this scheme, permanent magnet strength is controlled depending on magnetization direction, and consequently the final permanent magnet design converges into permanent magnet segments having target discrete directions. To validate the effectiveness of the proposed approach, three design examples are provided. The examples include the design of a dipole Halbach cylinder, magnetic system with arbitrarily-shaped cavity, and multi-objective problem resembling a magnetic refrigeration device.

  1. Optimization of permanent-magnet undulator magnets ordering using simulated annealing algorithm

    International Nuclear Information System (INIS)

    Chen Nian; He Duohui; Li Ge; Jia Qika; Zhang Pengfei; Xu Hongliang; Cai Genwang

    2005-01-01

    Pure permanent-magnet undulator consists of many magnets. The unavoidable remanence divergence of these magnets causes the undulator magnetic field error, which will affect the functional mode of the storage ring and the quality of the spontaneous emission spectrum. Optimizing permanent-magnet undulator magnets ordering using simulated annealing algorithm before installing undulator magnets, the first field integral can be reduced to 10 -6 T·m, the second integral to 10 -6 T·m 2 and the peak field error to less than 10 -4 . The optimized results are independent of the initial solution. This paper gives the optimizing process in detail and puts forward a method to quickly calculate the peak field error and field integral according to the magnet remanence. (authors)

  2. Repulsion analysis of permanent magnets for the Hoop energy storage system

    International Nuclear Information System (INIS)

    O, B. H.; Cho, S. B.; Kim, D. I.

    1996-01-01

    The repulsion force of permanent magnets is studied in order to analyze the instability problem of the rotational motion of a hoop levitated by permanent magnets in the Hoop Energy Storage System (HESS). The hoop of permanent magnets is levitated to remove the mechanical complexities caused by the rotational axis. It is important to maintain stable rotational motion at any speed for the efficiency as well as the safety of the system. To set up the equations of motion, the force of levitation and the source of perturbation are represented in terms of real parameters of the permanent magnets. The instability conditions and various geometric effects of the permanent magnets are analyzed. (author)

  3. Magnetic levitation force between a superconducting bulk magnet and a permanent magnet

    Energy Technology Data Exchange (ETDEWEB)

    Wang, J J; He, C Y; Meng, L F; Li, C; Han, R S; Gao, Z X [Department of Physics, Key Laboratory for Artificial Microstructure and Mesoscopic Physics, Peking University, Beijing 100871 (China)

    2003-04-01

    The current density J({rho}, z) in a disc-shaped superconducting bulk magnet and the magnetic levitation force F{sup SBM}{sub z} exerted on the superconducting bulk magnet by a cylindrical permanent magnet are calculated from first principles. The effect of the superconducting parameters of the superconducting bulk is taken into account by assuming the voltage-current law E = E{sub c}(J/J{sub c}){sup n} and the material law B = {mu}{sub 0}H. The magnetic levitation force F{sup SBM}{sub z} is dominated by the remnant current density J'{sub 2}({rho}, z), which is induced by switching off the applied magnetizing field. High critical current density and flux creep exponent may increase the magnetic levitation force F{sup SBM}{sub z}. Large volume and high aspect ratio of the superconducting bulk can further enhance the magnetic levitation force F{sup SBM}{sub z}.

  4. FY 1999 Report on research and development of power storage by high-temperature superconducting flywheel. Research and development of permanent magnet; 1999 nendo koon chodendo flywheel denryoku chozo kenkyu kaihatsu eikyu jishaku no kenkyu kaihatsu seika hokokusho

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2000-05-01

    The R and D program is implemented for permanent magnet, as part of the project aimed at commercialization of a 10 MWh-class high-temperature superconducting magnetic bearing type power storage system. A speed of rotation of 28,570 rpm is attained by using an iron intermediate ring for a Pr permanent magnet rotator and reinforcing the rotator with a plastic hoop reinforced with carbon fibers three-fold (CFPR hoop). The speed is increased to 31,300 rpm by interlacing carbon fibers also in the radial direction and replacing iron for the intermediate ring by titanium. The highest speed of rotation of 33,506 rpm is realized by the rotator of permanent magnet of sintered Nd. The magnetic circuit of stronger, more smooth magnetic field needs the permanent magnet of less uneven magnetic flux. The magnet is of a monoaxially anisotropic rare-earth metal, with four-fold magnetic ring bodies having fan-shaped small pieces arranged on each ring. Uneven magnetic flux occurs at the joint between these small pieces. The one-body-ring magnet of radially anisotropic, sintered Nd is developed, and incorporated in the repulsion type magnetic circuit, to reduce unevenness of the magnetic flux. (NEDO)

  5. A combination of permanent magnet and magnetic coil for a large diameter ion source

    International Nuclear Information System (INIS)

    Uramoto, Joshin; Kubota, Yusuke; Miyahara, Akira.

    1980-02-01

    A large diameter ion source for fast neutral beam injection is designed under a magnetic field (we call ''Uramoto Field'') composed of a circular ferrite permanent magnet and a usual coreless magnetic coil. As the magnetic filed is reduced abruptly in a discharge anode, an ion source with a uniform ion current density over a large diameter is produced easily without a ''button'' of ORNL duoPIGatron type ion source (a floating electrode to diffuse an axial plasma flow radially). (author)

  6. Simulation of magnetic induction distribution in a coaxial linear motor with axial and radial direction of permanent magnets magnetization

    Directory of Open Access Journals (Sweden)

    G.M. Golenkov

    2014-03-01

    Full Text Available The paper presents results of computer simulation and experimental study of magnetic induction distribution in a coaxial linear motor air gap throughout the length of the runner active part at different heights of the air gap between the runner and the inductor magnetic core for motors with axial and radial direction of the permanent magnets magnetization.

  7. Effect of microstructure changes on magnetic properties of spark plasma sintered Nd-Fe-B powders

    Directory of Open Access Journals (Sweden)

    Michalski B.

    2013-01-01

    Full Text Available In this study the SPS method was applied for low RE content (8,5% at. and high RE content (13,5 % at. MQ powders. The powders were sintered in a wide range of temperature, for 5 min., under pressure of 35 MPa. The low RE content grade, densified reluctantly and gained the density close to the theoretical value only for 850 °C. The coercivity decreased gradually with increasing sintering temperature. On the other hand, the densification of the higher RE content grade powder occurred much easier and the coercivity, close to the theoretical value, was achieved already at 650 °C. The coercivity of this material also decreased with increasing sintering temperature. Microstructural studies revealed that the SPS sintering process leads to partial decomposition of the Nd2Fe14B phase. The proportion of the RE-rich and iron phases increases parallel to the increasing sintering temperature. On the basis of the current results one can conclude that fabrication of high density MQ powders based magnets by the SPS method is possible, however the powders having higher RE content should be used for this purpose and the sintering temperature as low as possible, related to density, should be kept.

  8. Highly stable and finely tuned magnetic fields generated by permanent magnet assemblies.

    Science.gov (United States)

    Danieli, E; Perlo, J; Blümich, B; Casanova, F

    2013-05-03

    Permanent magnetic materials are the only magnetic source that can be used to generate magnetic fields without power consumption or maintenance. Such stand-alone magnets are very attractive for many scientific and engineering areas, but they suffer from poor temporal field stability, which arises from the strong sensitivity of the magnetic materials and mechanical support to temperature variation. In this work, we describe a highly efficient method useful to cancel the temperature coefficient of permanent magnet assemblies in a passive and accurate way. It is based on the combination of at least two units made of magnetic materials with different temperature coefficients arranged in such a way that the ratio of the fields generated by each unit matches the ratio of their effective temperature coefficients defined by both the magnetic and mechanical contributions. Although typically available magnetic materials have negative temperature coefficients, the cancellation is achieved by aligning the fields generated by each unit in the opposite direction. We demonstrate the performance of this approach by stabilizing the field generated by a dipolar Halbach magnet, recently proposed to achieve high field homogeneity. Both the field drift and the homogeneity are monitored via nuclear magnetic resonance spectroscopy experiments. The results demonstrate the compatibility of the thermal compensation approach with existing strategies useful to fine-tune the spatial dependence of the field generated by permanent magnet arrays.

  9. [Development of RF coil of permanent magnet mini-magnetic resonance imager and mouse imaging experiments].

    Science.gov (United States)

    Hou, Shulian; Xie, Huantong; Chen, Wei; Wang, Guangxin; Zhao, Qiang; Li, Shiyu

    2014-10-01

    In the development of radio frequency (RF) coils for better quality of the mini-type permanent magnetic resonance imager for using in the small animal imaging, the solenoid RF coil has a special advantage for permanent magnetic system based on analyses of various types.of RF coils. However, it is not satisfied for imaging if the RF coils are directly used. By theoretical analyses of the magnetic field properties produced from the solenoid coil, the research direction was determined by careful studies to raise further the uniformity of the magnetic field coil, receiving coil sensitivity for signals and signal-to-noise ratio (SNR). The method had certain advantages and avoided some shortcomings of the other different coil types, such as, birdcage coil, saddle shaped coil and phased array coil by using the alloy materials (from our own patent). The RF coils were designed, developed and made for keeled applicable to permanent magnet-type magnetic resonance imager, multi-coil combination-type, single-channel overall RF receiving coil, and applied for a patent. Mounted on three instruments (25 mm aperture, with main magnetic field strength of 0.5 T or 1.5 T, and 50 mm aperture, with main magnetic field strength of 0.48 T), we performed experiments with mice, rats, and nude mice bearing tumors. The experimental results indicated that the RF receiving coil was fully applicable to the permanent magnet-type imaging system.

  10. Discrete Current Control Strategy of Permanent Magnet Synchronous Motors

    Directory of Open Access Journals (Sweden)

    Yan Dong

    2013-01-01

    Full Text Available A control strategy of permanent magnet synchronous motors (PMSMs, which is different from the traditional vector control (VC and direct torque control (DTC, is proposed. Firstly, the circular rotating magnetic field is analyzed on the simplified model and discredited into stepping magnetic field. The stepping magnetomotive force will drive the rotor to run as the stepping motor. Secondly, the stator current orientation is used to build the control model instead of rotor flux orientation. Then, the discrete current control strategy is set and adopted in positioning control. Three methods of the strategy are simulated in computer and tested on the experiment platform of PMSM. The control precision is also verified through the experiment.

  11. Magnetic entropy of the mixed and sintered compound of the RAl/sub 2/ system

    International Nuclear Information System (INIS)

    Kuzuhara, T.; Wakabayashi, H.; Matsumoto, K.; Hashimoto, T.; Sahashi, M.; Inomata, K.; Tomokiyo, A.; Yayama, H.

    1986-01-01

    The magnetic refrigerant for the Ericsson type magnetic refrigerator should have a constant magnetic entropy difference ΔS/sub J/ between two constant magnetic field processes. However, the magnetic entropy change of an homogeneous ferromagnet exhibits a sharp peak at the Curie temperature. In the present investigation the authors succeeded to make the layer structural sintered composite composed of several kinds of RAl/sub 2/ compounds having large entropy change near their Curie temperatures and made clear that this composite has the constant πS/sub J/ in the wide temperature range suitable for the Ericsson cycle

  12. A novel permanent maglev rotary LVAD with passive magnetic bearings.

    Science.gov (United States)

    Qian, K X; Yuan, H Y; Zeng, P; Ru, W M

    2005-01-01

    It has been widely acknowledged that permanent maglev cannot achieve stability; however, the authors have discovered that stable permanent maglev is possible under the effect of a combination of passive magnetic and nonmagnetic forces. In addition, a rotary left ventricular assist device (LVAD) with passive magnetic bearings has been developed. It is a radially driven impeller pump, having a rotor and a stator. The rotor consists of driven magnets and impeller; the motor coil and pump housing form the stator. Two passive magnetic bearings counteract the attractive force between motor coil iron core and rotor magnets; the rotor thereafter can be disaffiliated from the stator and become levitated under the action of passive magnetic and haemodynamic forces. Because of the pressure difference between the outlet and the inlet of the pump, there is a small flow passing through the gap of rotor and stator, and then entering the lower pressure area along the central hole of the rotor. This small flow comes to a full washout of all blood contacting surfaces in the motor. Moreover, a decreased Bernoulli force in the larger gap with faster flow produces a centring force that leads to stable levitation of the rotor. Resultantly, neither mechanical wear nor thrombosis will occur in the pump. The rotor position detection reveals that the precondition of levitation is a high rotating speed (over 3250 rpm) and a high flow rate (over 1 l min(-1)). Haemodynamic tests with porcine blood indicate that the device as a LVAD requires a rotating speed between 3500 and 4000 rpm for producing a blood flow of 4 - 6 l min(-1) against 100 mmHg mean pressure head. The egg-sized device has a weight of 200 g and an O.D. of 40 mm at its largest point.

  13. Laboratory scale fabrication of Nd-Fe-B sintered magnets

    International Nuclear Information System (INIS)

    Rodrigues, Daniel; Beneduce Neto, Flavio; Landgraf, Fernando Jose Gomes; Neiva, Augusto Camara; Romero, Sergio; Missell, Frank Patrick

    1992-01-01

    Results are presented on magnetic properties of Nd-Fe-B sauntered magnets produced from 1 kg of alloy caste in vacuum induction furnace. The fabrication viability of these magnets, with properties similar to the commercial magnets, and the influence of particle size in the energy product, through the effect on the H k field, is confirmed

  14. On a neutral particle with permanent magnetic dipole moment in a magnetic medium

    Science.gov (United States)

    Bakke, K.; Salvador, C.

    2018-03-01

    We investigate quantum effects that stem from the interaction of a permanent magnetic dipole moment of a neutral particle with an electric field in a magnetic medium. We consider a long non-conductor cylinder that possesses a uniform distribution of electric charges and a non-uniform magnetization. We discuss the possibility of achieving this non-uniform magnetization from the experimental point of view. Besides, due to this non-uniform magnetization, the permanent magnetic dipole moment of the neutral particle also interacts with a non-uniform magnetic field. This interaction gives rise to a linear scalar potential. Then, we show that bound states solutions to the Schrödinger-Pauli equation can be achieved.

  15. Post-assembly magnetization of a 100 kW high speed permanent magnet rotor.

    Science.gov (United States)

    Lv, Yiliang; Wang, Guobin; Li, Liang

    2015-03-01

    A post-assembly magnetizing fixture has been designed and successfully used to magnetize the rotor of a 100 kW high speed permanent magnet synchronous motor. The rotor is a solid cylinder with outer diameter of 80 mm and total length of 515 mm. The permanent magnet material is samarium-cobalt (Sm2Co17) with saturation magnetizing field of 6 T. The mechanical stability of the magnetizing fixture has been studied as well as the general design methodology. The magnetizing coil is subdivided in order to reduce the electromagnetic force, and the coils are separately reinforced in different ways. The electromagnetic and structural optimization is performed by finite element analysis and verified by experiments.

  16. Post-assembly magnetization of a 100 kW high speed permanent magnet rotor

    International Nuclear Information System (INIS)

    Lv, Yiliang; Wang, Guobin; Li, Liang

    2015-01-01

    A post-assembly magnetizing fixture has been designed and successfully used to magnetize the rotor of a 100 kW high speed permanent magnet synchronous motor. The rotor is a solid cylinder with outer diameter of 80 mm and total length of 515 mm. The permanent magnet material is samarium-cobalt (Sm 2 Co 17 ) with saturation magnetizing field of 6 T. The mechanical stability of the magnetizing fixture has been studied as well as the general design methodology. The magnetizing coil is subdivided in order to reduce the electromagnetic force, and the coils are separately reinforced in different ways. The electromagnetic and structural optimization is performed by finite element analysis and verified by experiments

  17. Post-assembly magnetization of a 100 kW high speed permanent magnet rotor

    Energy Technology Data Exchange (ETDEWEB)

    Lv, Yiliang; Wang, Guobin [Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan (China); Li, Liang [Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan (China); State Key Laboratory of Advanced Electromagnetic Engineering and Technology, Huazhong University of Science and Technology, Wuhan (China)

    2015-03-15

    A post-assembly magnetizing fixture has been designed and successfully used to magnetize the rotor of a 100 kW high speed permanent magnet synchronous motor. The rotor is a solid cylinder with outer diameter of 80 mm and total length of 515 mm. The permanent magnet material is samarium-cobalt (Sm{sub 2}Co{sub 17}) with saturation magnetizing field of 6 T. The mechanical stability of the magnetizing fixture has been studied as well as the general design methodology. The magnetizing coil is subdivided in order to reduce the electromagnetic force, and the coils are separately reinforced in different ways. The electromagnetic and structural optimization is performed by finite element analysis and verified by experiments.

  18. Microscopic observation of magnetic bacteria in the magnetic field of a rotating permanent magnet.

    Science.gov (United States)

    Smid, Pieter; Shcherbakov, Valeriy; Petersen, Nikolai

    2015-09-01

    Magnetotactic bacteria are ubiquitous and can be found in both freshwater and marine environments. Due to intracellular chains of magnetic single domain particles, they behave like swimming compass needles. In external magnetic fields like the Earth's magnetic field, a torque is acting on the chain. This will cause the bacterium to be rotated and aligned with the external field. The swimming direction of magnetotactic bacteria can be controlled with external magnetic fields, which makes it convenient to study them under a light microscope. Usually, a special set of coils arranged around a light microscope is used to control the swimming magnetotactic bacteria. Here, we present a simple mechanical system with a permanent magnet, which produces a rotating magnetic field of nearly constant amplitude in the focal plane of a light microscope. The device is placed beside the light microscope and easily adaptable to almost any microscope and thus convenient for field experiments. To describe the trajectories qualitatively, a theoretical model of the trajectories is presented. This device can be used to control the swimming direction of magnetotactic bacteria and also for studying their magnetic and hydrodynamic properties.

  19. Magnetization curves of sintered heavy tungsten alloys for applications in MRI-guided radiotherapy

    International Nuclear Information System (INIS)

    Kolling, Stefan; Oborn, Bradley M.; Keall, Paul J.; Horvat, Joseph

    2014-01-01

    Purpose: Due to the current interest in MRI-guided radiotherapy, the magnetic properties of the materials commonly used in radiotherapy are becoming increasingly important. In this paper, measurement results for the magnetization (BH) curves of a range of sintered heavy tungsten alloys used in radiation shielding and collimation are presented. Methods: Sintered heavy tungsten alloys typically contain >90 % tungsten and 0 and the BH curve derived. Results: The iron content of the alloys was found to play a dominant role, directly influencing the magnetizationM and thus the nonlinearity of the BH curve. Generally, the saturation magnetization increased with increasing iron content of the alloy. Furthermore, no measurable magnetization was found for all alloys without iron content, despite containing up to 6% of nickel. For two samples from different manufacturers but with identical quoted nominal elemental composition (95% W, 3.5% Ni, 1.5% Fe), a relative difference in the magnetization of 11%–16% was measured. Conclusions: The measured curves show that the magnetic properties of sintered heavy tungsten alloys strongly depend on the iron content, whereas the addition of nickel in the absence of iron led to no measurable effect. Since a difference in the BH curves for two samples with identical quoted nominal composition from different manufacturers was observed, measuring of the BH curve for each individual batch of heavy tungsten alloys is advisable whenever accurate knowledge of the magnetic properties is crucial. The obtained BH curves can be used in FEM simulations to predict the magnetic impact of sintered heavy tungsten alloys

  20. A novel structure of permanent-magnet-biased radial hybrid magnetic bearing

    International Nuclear Information System (INIS)

    Sun Jinji; Fang Jiancheng

    2011-01-01

    The paper proposes a novel structure for a permanent-magnet-biased radial hybrid magnetic bearing. Based on the air gap between the rotor and stator of traditional radial hybrid magnetic bearings, a subsidiary air gap is first constructed between the permanent magnets and the inner magnetic parts. Radial magnetic bearing makes X and Y magnetic fields independent of each other with separate stator poles, and the subsidiary air gap makes control flux to a close loop. As a result, magnetic field coupling of the X and Y channels is decreased significantly by the radial hybrid magnetic bearing and makes it easier to design control systems. Then an external rotor structure is designed into the radial hybrid magnetic bearing. The working principle of the radial hybrid magnetic bearing and its mathematical model is discussed. Finally, a non-linear magnetic network method is proposed to analyze the radial hybrid magnetic bearing. Simulation results indicate that magnetic fields in the two channels of the proposed radial hybrid magnetic bearing decouple well from each other.

  1. A novel structure of permanent-magnet-biased radial hybrid magnetic bearing

    Energy Technology Data Exchange (ETDEWEB)

    Sun Jinji, E-mail: sunjinji@aspe.buaa.edu.c [Key Laboratory of Fundamental Science for National Defense, Novel Inertial Instrument and Navigation System Technology, School of Instrument Science and Opto-electronics Engineering, Beijing University of Aeronautics and Astronautics, 100191 (China); Fang Jiancheng [Key Laboratory of Fundamental Science for National Defense, Novel Inertial Instrument and Navigation System Technology, School of Instrument Science and Opto-electronics Engineering, Beijing University of Aeronautics and Astronautics, 100191 (China)

    2011-01-15

    The paper proposes a novel structure for a permanent-magnet-biased radial hybrid magnetic bearing. Based on the air gap between the rotor and stator of traditional radial hybrid magnetic bearings, a subsidiary air gap is first constructed between the permanent magnets and the inner magnetic parts. Radial magnetic bearing makes X and Y magnetic fields independent of each other with separate stator poles, and the subsidiary air gap makes control flux to a close loop. As a result, magnetic field coupling of the X and Y channels is decreased significantly by the radial hybrid magnetic bearing and makes it easier to design control systems. Then an external rotor structure is designed into the radial hybrid magnetic bearing. The working principle of the radial hybrid magnetic bearing and its mathematical model is discussed. Finally, a non-linear magnetic network method is proposed to analyze the radial hybrid magnetic bearing. Simulation results indicate that magnetic fields in the two channels of the proposed radial hybrid magnetic bearing decouple well from each other.

  2. Analysis of an adjustable field permanent magnet solenoid

    Science.gov (United States)

    Burris-Mog, T.; Burns, M.; Chavez, A.; Schillig, J.

    2017-10-01

    A feasibility study has been performed on an adjustable-field permanent magnet (PM) solenoid concept in an effort to reduce the dependence that linear induction accelerators have on large direct current power supplies and associated cooling systems. The concept relies on the ability to reorient sections of the PMs and thus redirect their magnetization vector to either add to or subtract from the on-axis magnetic field. This study concentrated on the focal strengths and emittance growths for two different designs, both with 19 cm bore diameters extending 53 cm in length. The first design is expected to produce peak magnetic fields ranging from 260 to 900 G (0.026 to 0.09 T) while the second design is expected to produce peak magnetic fields ranging from 580 to 2100 G (0.058 to 0.21 T). Although the PM configuration generates a variable magnetic field and the torques acting on PMs within the assembly appear manageable, the emittance growth is larger than that of a DC solenoid.

  3. Self-suspended permanent magnetic FePt ferrofluids

    KAUST Repository

    Dallas, Panagiotis

    2013-10-01

    We present the synthesis and characterization of a new class of self-suspended ferrofluids that exhibit remanent magnetization at room temperature. Our system relies on the chemisorption of a thiol-terminated ionic liquid with very low melting point on the surface of L10 FePt nanoparticles. In contrast, all types of ferrofluids previously reported employ either volatile solvents as the suspending media or superparamagnetic iron oxide nanoparticles (that lacks permanent magnetization) as the inorganic component. The ferrofluids do not show any sign of flocculation or phase separation, despite the strong interactions between the magnetic nanoparticles due to the strong chemisorption of the ionic liquid as evidenced by Raman spectroscopy and thermal analysis. Composites with high FePt loading (40 and 70. wt%) exhibit a pseudo solid-like rheological behavior and high remanent magnetization values (10.1 and 12.8. emu/g respectively). At lower FePt loading (12. wt%) a liquid like behavior is observed and the remanent and saturation magnetization values are 3.5 and 6.2. emu/g, respectively. The magnetic and flow properties of the materials can be easily fine tuned by controlling the type and amount of FePt nanoparticles used. © 2013 Elsevier Inc.

  4. Permanent magnetic ferrite based power-tunable metamaterials

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Guanqiao; Lan, Chuwen [State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Gao, Rui [High Temperature Thermochemistry Laboratory, Department of Mining and Materials Engineering, McGill University, Montreal, Quebec H3A 0C5 (Canada); Zhou, Ji, E-mail: zhouji@tsinghua.edu.cn [State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China)

    2017-08-15

    Highlights: • Power-tunable metamaterials based on barium permanent magnetic ferrite have been proposed and fabricated. • It is observed that resonant frequency of the array shifts upon altering the output power. • This kind of power-tunable behavior is due to the temperature rise as a result of FMR-induced heat buildup. • This work offers a practical idea to tune ferrite metamaterials besides magneto-tunability and thermal-tunability. - Abstract: Power-tunable metamaterials based on barium permanent magnetic ferrite have been proposed and fabricated in this research. Scattering parameter measurements confirm a shift in resonant frequency in correlation to changes in incident electromagnetic power within microwave frequency band. The tunable phenomenon represented by a blue-shift in transmission spectra in the metamaterials array can be attributed to a decrease in saturation magnetization resulting from FMR-induced temperature elevation upon resonant conditions. This power-dependent behavior offers a simple and practical route towards dynamically fine-tunable ferrite metamaterials.

  5. Slip Torque Investigation and Magnetic Redesign of Motor Integrated Permanent Magnet Gear

    DEFF Research Database (Denmark)

    Frandsen, Tommy Vestergaard; Rasmussen, Peter Omand

    2015-01-01

    This paper presents an investigation of 20% difference between the measured and calculated slip torque of a Motor Integrated Permanent Magnet Gear (MIPMG) prototype. The High Speed (HS) side of the Magnetic Gear (MG) was fixed by loading the motor when conducting the slip torque measurement. Susp...

  6. Improvement of permanent magnet machines performance by including magnetic shells into the rotor geometry

    International Nuclear Information System (INIS)

    Alnaemi, F.; Moses, A.J.

    2003-01-01

    FEM modelling of PM motor was carried out to demonstrate the effects of the addition of various types of ferromagnetic tubes (shell) to a rotor of surface mount permanent magnet motor. An enhancement in magnet operating point towards the high field region is obtained. A shell made of amorphous ribbon offers optimum advantages

  7. Improving torque per kilogram magnet of permanent magnet couplings using finite element analysis

    DEFF Research Database (Denmark)

    Högberg, Stig; Jensen, Bogi Bech; Bendixen, Flemming Buus

    2013-01-01

    This paper presents the methodology and subsequent findings of a performance-improvement routine that employs automated finite element (FE) analysis to increase the torque-per-kilogram-magnet (TPKM) of a permanent magnet coupling (PMC). The routine is applied to a commercially available cylindrical...

  8. Microstructural evaluation and magnetic Ni-Zn ferrite sintered by microwave energy

    International Nuclear Information System (INIS)

    Diniz, Veronica Cristhina S.; Vieira, Debora A.; Costa, Ana Cristina F.M.; Kiminami, R.H.G.A.; Cornejo, Daniel Reinaldo

    2011-01-01

    The present Ni-Zn ferrite magnetic properties sensitive to microstructure and obtain a ferrite with a uniform microstructure is the biggest challenge in the advancement of new technologies. This study proposes to evaluate the microstructure and magnetic properties of Ni-Zn ferrite sintered by microwave energy. The samples were previously synthesized by combustion reaction using urea and glycine, with 1200 deg C/2h sintered at a heating rate of 5 deg C/min, and characterized by density, XRD, SEM and magnetic measurements. The results show that the sample synthesized with glycine showed the formation of ferrite phase and traces of secondary phase hematite, grains with undefined format, and a high porosity and inter intragranular. The sample synthesized with urea gave only the ferrite phase, with hexagonal grains, and low intergranular porosity. The sample synthesized with urea showed better magnetic characteristics when compared with the samples synthesized with glycine. (author)

  9. Motor Integrated Permanent Magnet Gear in a Battery Electrical Vehicle

    DEFF Research Database (Denmark)

    Frandsen, Tommy; Mathe, Laszlo; Berg, Nick Ilsø

    2015-01-01

    This paper presents the physical construction and test results of two new demonstrators of a Motor Integrated Permanent Magnet Gear (MIPMG), which is a second version of an already tested demonstrator. The demonstrators will be used as traction units for a Battery Electrical Vehicle (BEV......) and the background for the specifications are elaborated. Simulated as well as measured results of rotational losses of the first and second version are compared. The efficiency of the new design is investigated and compared to three direct drive motors in a few operating points and the MIPMG v.2 seems superior when...

  10. Impulsive control of permanent magnet synchronous motors with parameters uncertainties

    International Nuclear Information System (INIS)

    Li Dong; Zhang Xiaohong; Wang Shilong; Yan Dan; Wang Hui

    2008-01-01

    The permanent magnet synchronous motors (PMSMs) may have chaotic behaviours for the uncertain values of parameters or under certain working conditions, which threatens the secure and stable operation of motor-driven. It is important to study methods of controlling or suppressing chaos in PMSMs. In this paper, robust stabilities of PMSM with parameter uncertainties are investigated. After the uncertain matrices which represent the variable system parameters are formulated through matrix analysis, a novel asymptotical stability criterion is established. Some illustrated examples are also given to show the effectiveness of the obtained results

  11. Nonlinear chaos control in a permanent magnet reluctance machine

    International Nuclear Information System (INIS)

    Harb, Ahmad M.

    2004-01-01

    The dynamics of a permanent magnet synchronous machine (PMSM) is analyzed. The study shows that under certain conditions the PMSM is experiencing chaotic behavior. To control these unwanted chaotic oscillations, a nonlinear controller based on the backstepping nonlinear control theory is designed. The objective of the designed control is to stabilize the output chaotic trajectory by forcing it to the nearest constant solution in the basin of attraction. The result is compared with a nonlinear sliding mode controller. The designed controller that based on backstepping nonlinear control was able to eliminate the chaotic oscillations. Also the study shows that the designed controller is mush better than the sliding mode control

  12. Conceptual designs for NLC ubitrons with permanent-magnet wigglers

    International Nuclear Information System (INIS)

    Phillips, R.

    1994-09-01

    This paper describes three embodiments of the ubitron (FEL) amplifier that will be analyzed for possible use on the NLC. The design frequency and power are 11.424 GHz and 200 MW peak rf output power. The baseline against which these conceptual designs are to be evaluated is the PPM-focused 50-MW SIAC klystron, which in simulation shows 65% efficiency. In order to remain competitive in cost and power consumption, only ubitron beam-wave configurations that can use permanent-magnet wigglers are considered

  13. Axial Permanent Magnet Generator for Wearable Energy Harvesting

    DEFF Research Database (Denmark)

    Högberg, Stig; Sødahl, Jakob Wagner; Mijatovic, Nenad

    2016-01-01

    An increasing demand for battery-free electronics is evident by the rapid increase of wearable devices, and the design of wearable energy harvesters follows accordingly. An axial permanent magnet generator was designed to harvest energy from human body motion and supplying it to a wearable......W, respectively) with an iron yoke is subject to losses that exceed the realistic input power, and was therefore deemed infeasible. A generator without the iron yoke was concluded to perform well as a wearable energy harvester. An experimental investigation of a prototype revealed an output power of almost 1 m...

  14. Fuzzy adaptive speed control of a permanent magnet synchronous motor

    Science.gov (United States)

    Choi, Han Ho; Jung, Jin-Woo; Kim, Rae-Young

    2012-05-01

    A fuzzy adaptive speed controller is proposed for a permanent magnet synchronous motor (PMSM). The proposed fuzzy adaptive speed regulator is insensitive to model parameter and load torque variations because it does not need any accurate knowledge about the motor parameter and load torque values. The stability of the proposed control system is also proven. The proposed adaptive speed regulator system is implemented by using a TMS320F28335 floating point DSP. Simulation and experimental results are presented to verify the effectiveness of the proposed fuzzy adaptive speed controller under uncertainties such as motor parameter and load torque variations using a prototype PMSM drive system.

  15. Alloy design of Nd2, Fe14B permanent magnets

    International Nuclear Information System (INIS)

    Horton, J.A.; Herchenroeder, J.W.

    2000-01-01

    This report summarizes the results of research conducted as part of CRADA ORNL94-0279 between Oak Ridge National Laboratory and Magnequench International, Inc. The objective was to gain a better understanding of the fracture process in the rare earth based permanent magnets in order to possibly improve the mechanical properties of these inherently brittle intermetallics. The first part of the study established a technique for measuring a critical property, fracture toughness, and surveying currently available commercial material made by a number of different processes

  16. Nerve-muscle activation by rotating permanent magnet configurations.

    Science.gov (United States)

    Watterson, Peter A; Nicholson, Graham M

    2016-04-01

    The standard method of magnetic nerve activation using pulses of high current in coils has drawbacks of high cost, high electrical power (of order 1 kW), and limited repetition rate without liquid cooling. Here we report a new technique for nerve activation using high speed rotation of permanent magnet configurations, generating a sustained sinusoidal electric field using very low power (of order 10 W). A high ratio of the electric field gradient divided by frequency is shown to be the key indicator for nerve activation at high frequencies. Activation of the cane toad sciatic nerve and attached gastrocnemius muscle was observed at frequencies as low as 180 Hz for activation of the muscle directly and 230 Hz for curved nerves, but probably not in straight sections of nerve. These results, employing the first prototype device, suggest the opportunity for a new class of small low-cost magnetic nerve and/or muscle stimulators. Conventional pulsed current systems for magnetic neurostimulation are large and expensive and have limited repetition rate because of overheating. Here we report a new technique for nerve activation, namely high-speed rotation of a configuration of permanent magnets. Analytical solutions of the cable equation are derived for the oscillating electric field generated, which has amplitude proportional to the rotation speed. The prototype device built comprised a configuration of two cylindrical magnets with antiparallel magnetisations, made to rotate by interaction between the magnets' own magnetic field and three-phase currents in coils mounted on one side of the device. The electric field in a rectangular bath placed on top of the device was both numerically evaluated and measured. The ratio of the electric field gradient on frequency was approximately 1 V m(-2) Hz(-1) near the device. An exploratory series of physiological tests was conducted on the sciatic nerve and attached gastrocnemius muscle of the cane toad (Bufo marinus). Activation was

  17. Magnetic Behavior of Sintered NdFeB Magnets on a Long-Term Timescale

    Directory of Open Access Journals (Sweden)

    Minna Haavisto

    2014-01-01

    Full Text Available Stable polarization of permanent magnets over the lifetime of the application is an important aspect in electrical machine design. Specification of the long-term stability of magnet material is difficult, since knowledge of the phenomenon is incomplete. To be able to optimize magnet material selection, the long-term magnetic behavior of the material must also be understood. This study shows that material with a very square JH curve is stable until a certain critical operating temperature is reached. Major losses are detected as the critical temperature is exceeded. Material with a rounder JH curve does not show a well-defined critical temperature, but increasing losses over a large temperature range. The critical temperature of a material is also dependent on the field conditions. Results differ whether the tests are performed in an open or closed magnetic circuit. In open-circuit tests, the opposing field is not homogeneously distributed throughout the volume of the magnet and thus the long-term behavior is different than that in closed-circuit conditions. Open-circuit tests seem to give bigger losses than closed-circuit tests in cases where the permeance coefficient of the open-circuit sample is considered to be the average permeance coefficient, calculated according to the dimensions of the magnet.

  18. Pressless process in route of obtaining sintered Nd–Fe–B magnets

    Energy Technology Data Exchange (ETDEWEB)

    Popov, A.G, E-mail: apopov@imp.uran.ru [Institute of Metal Physics, UB of the RAS, 18, S. Kovalevskoy, Street, 620990 Ekaterinburg (Russian Federation); Golovnia, O.A. [Institute of Metal Physics, UB of the RAS, 18, S. Kovalevskoy, Street, 620990 Ekaterinburg (Russian Federation); Bykov, V.A. [Institute of Metallurgy, UB of the RAS, 101, Amundsena, Street, 620016 Ekaterinburg (Russian Federation)

    2015-06-01

    A short review on the pressless process (PLP) involved in the manufacture of sintered Nd–Fe–B magnet is given. Two approaches to increasing the degree of powder alignment with a high filling density ρ{sub f} in PLP-containers are proposed. (1) An increase in the pulse duration of applied magnetic field from 3.6 to 6.5 ms enhances the magnetic alignment of magnets prepared from the powder with ρ{sub f}=2.5 g/cm{sup 3} and ρ{sub f}=3 g/cm{sup 3} by 3% and 11%, respectively. (2) Addition of internal lubricants such as zinc stearate or esters reduces friction forces between the powder particles and, when the concentration of lubricants is bellow a critical concentration C{sub cr}, increases B{sub r} and (BH){sub max} by 5–7%. Simulation of the magnetic alignment of uniaxial particles demonstrates that a decrease in the coefficient of friction between the powder particles from 0.9 to 0.6 caused by the lubricant addition enhances the alignment degree. Contact dilatometry was used to study the anisotropy of densification of PLP-powders upon sintering. It has been shown that the anisotropy of the powder shrinkage is formed at the first stage of sintering at the temperature about 800 °C and is caused by the capillary action in the Nd-rich liquid. - Highlights: • A review of the pressless process for NdFeB magnets in the world and Russia is given. • Enhancement of the alignment degree by application of pulsed magnetic field is studied. • Reduction of the friction forces via addition of internal lubricants is proposed. • The simulation of the magnetic alignment of Nd–Fe–B uniaxial particles is presented. • A reason of anisotropic shrinkage of the powder at sintering is suggested.

  19. Steelmaking slag beneficiation by magnetic separator and impacts on sinter quality

    Directory of Open Access Journals (Sweden)

    Bölükbaşı Ö.S.

    2014-01-01

    Full Text Available Basic oxygen furnaces (BOF slag is the main problem at all iron and steel factories. About more than 6 million tons/year of BOF slag has been accumulated from the waste stockyards in Turkey. Dumps slags can be revaluated by a processing technology which makes it possible to obtain products that meet the requirements of sintering and blast furnace production. The slags with particle size of -10 mm were enriched by the magnetic separator resulting and increase in Fe grade from 18% to 33%. The use of BOF slag in sinter blend provided additional Mn, CaO, MgO and introduced a good solution to environmental problems.

  20. Magnetization reversal processes of isotropic permanent magnets with various inter-grain exchange interactions

    Directory of Open Access Journals (Sweden)

    Hiroshi Tsukahara

    2017-05-01

    Full Text Available We performed a large-scale micromagnetics simulation on a supercomputing system to investigate the properties of isotropic nanocrystalline permanent magnets consisting of cubic grains. In the simulation, we solved the Landau–Lifshitz–Gilbert equation under a periodic boundary condition for accurate calculation of the magnetization dynamics inside the nanocrystalline isotropic magnet. We reduced the inter-grain exchange interaction perpendicular and parallel to the external field independently. Propagation of the magnetization reversal process is inhibited by reducing the inter-grain exchange interaction perpendicular to the external field, and the coercivity is enhanced by this restraint. In contrast, when we reduce the inter-grain exchange interaction parallel to the external field, the coercivity decreases because the magnetization reversal process propagates owing to dipole interaction. These behaviors show that the coercivity of an isotropic permanent magnet depends on the direction of the inter-grain exchange interaction.

  1. A magnetic filter with permanent magnets on the basis of rare earths

    International Nuclear Information System (INIS)

    Zezulka, V.Vaclav; Straka, Pavel; Mucha, Pavel

    2004-01-01

    The article presents the development and construction of a magnetic filter based on the HGMS principle with permanent magnets. It is aimed especially at the assembly of the magnetic circuit using magnets from the material NdFeB. The way of the construction of large magnetic blocks, their magnetization and assembly are described. Further, it contains the measured values of magnetic induction in the middle of the air gap as a function of the width of this gap and of the height of the magnetic blocks in question, as well as the corresponding graphic representation. The high values of the magnetic induction obtained together with favourable price are sufficient reasons for the employment of this type of magnetic circuit in various applications

  2. Production and corrosion resistance of NdFeBZr magnets with an improved response to thermal variations during sintering

    International Nuclear Information System (INIS)

    Yu, L.Q.; Zhong, X.L.; Zhang, Y.P.; Yan, Y.G.; Zhen, Y.H.; Zakotnik, M.

    2011-01-01

    This study describes an attempt to produce NdFeB magnets that are insensitive to the sintering temperature. It was found that addition of Zr to NdFeB magnets significantly augmented the thermal stability of this magnetic material during sintering at high temperature even at industrial scale. The best sintered magnets were produced by jet-milling the powder (to achieve an average 3.4 μm particle size), and then aligned, pressed and sintered under argon at 1100 o C for 3 h followed by appropriate heat treatment. The magnetic properties of the resulting magnets were: (BH) m =403.8 kJ m -3 (±4.7 kJ m -3 ), B r =1430 mT (±9 mT) and i H c =907 kA m -1 (±12 kA m -1 ). Large grain growth, in excess of 100 μm in the Zr-free magnets, was observed during sintering at 1100 o C. This did not occur in the presence of Zr. These observations imply that the sensitivity of this class of magnets to high sintering temperatures is greatly reduced by Zr addition. Corrosion resistance of NdFeB was therefore significantly improved by the addition of small amounts of Zr. - Research highlights: →This study describes an attempt to produce NdFeB magnets that are insensitive to the sintering temperature. → It was found that addition of Zr to NdFeB magnets significantly augmented the thermal stability of this magnetic material during sintering at high temperature; even at industrial scale. → The magnetic properties of the resulting magnets were: (BH) m =403.8 kJ m -3 (±4.7 kJ m -3 ), B r =1430 mT (±9 mT) and i H c =907 kA m -1 (±12 kA m -1 ).

  3. Using axial magnetized permanent rings to build axial gradient magnetic field

    International Nuclear Information System (INIS)

    Peng Quanling

    2003-01-01

    Axial field produced by an axially magnetized permanent ring was studied. For two permanent magnet rings, if they are magnetized in the same direction, a nearly uniform axial field can be produced; if they are magnetized in opposite direction, an axial gradient field can be produced in the region between the two permanent rings, with the field strength changing from -B 0 to B 0 . A high gradient axial magnetic field has been built by using two axially magnetized permanent rings, the measured field results agree with the PANDIRA calculation very well. It is desirable that the field gradient can be varied to match various requirements. A method to produce the variable gradient field is presented. Axial gradient field can also be used as a beam focusing facility for linear accelerator if axial periodic field can be produced. Its magnetic field is similar to that of a solenoid, in which, large stray field will leak to the outside environment. A method for shielding the outside stray field is discussed

  4. Corrosion of NdFeB permanent magnet materials

    International Nuclear Information System (INIS)

    Warren, G.W.; Gao, G.; Li, Q.

    1991-01-01

    NdFeB is an important class of new magnetic materials, however corrosion resistance is a serious concern and literature on the electrochemical behavior of NdFeB is scarce. This paper reports the results of an electrochemical investigation of the corrosion behavior of sintered NdFeB magnets obtained from three manufacturers. Linear polarization (cyclic voltammetry) experiments were conducted in aqueous solutions ranging in pH from 0.7 to 13.5. A limited degree of passivation was observed in all solutions which is believed to be due to the formation of a complex Fe-Nd oxide and/or hydroxide film. The presence of a small amount of chloride ion, 10 to 100 ppm, shows only a slight effect, but higher concentrations (1000 ppm) cause a total breakdown in passivity and a dramatic increase in anodic current. The cathodic potential sweep shows an abrupt and unusual oxidation process, giving rise to an oxidation peak not commonly seen. This peak may result from dissolution of the film or preferential attack of intergranular phases

  5. Additive Manufacturing of Near-net Shaped Permanent Magnets

    Energy Technology Data Exchange (ETDEWEB)

    Paranthaman, M Parans [ORNL

    2016-07-26

    The technical objective of this technical collaboration phase I proposal is to fabricate near net-shaped permanent magnets using alloy powders utilizing direct metal deposition technologies at the ORNL MDF. Direct Manufacturing using the POM laser system was used to consolidate Nd2Fe14B (NdFeB) magnet powders into near net-shape parts efficiently and with virtually no wasted material as part of the feasibility study. We fabricated builds based on spherical NdFeB magnet particles. The results show that despite the ability to fabricate highly reactive materials in the laser deposition process, the magnetic coercivity and remanence of the NdFeB hard magnets is significantly reduced. X-ray powder diffraction in conjunction with electron microscopy showed that the material experienced a primary Nd2Fe17Bx solidification due to the undercooling effect (>60K). Consequently the presence of alpha iron phase resulted in deterioration of the build properties. Further optimization of the processing parameters is needed to maintain the Nd2Fe14B phase during fabrication.

  6. Nerve–muscle activation by rotating permanent magnet configurations

    Science.gov (United States)

    Nicholson, Graham M.

    2016-01-01

    Key points The standard method of magnetic nerve activation using pulses of high current in coils has drawbacks of high cost, high electrical power (of order 1 kW), and limited repetition rate without liquid cooling.Here we report a new technique for nerve activation using high speed rotation of permanent magnet configurations, generating a sustained sinusoidal electric field using very low power (of order 10 W).A high ratio of the electric field gradient divided by frequency is shown to be the key indicator for nerve activation at high frequencies.Activation of the cane toad sciatic nerve and attached gastrocnemius muscle was observed at frequencies as low as 180 Hz for activation of the muscle directly and 230 Hz for curved nerves, but probably not in straight sections of nerve.These results, employing the first prototype device, suggest the opportunity for a new class of small low‐cost magnetic nerve and/or muscle stimulators. Abstract Conventional pulsed current systems for magnetic neurostimulation are large and expensive and have limited repetition rate because of overheating. Here we report a new technique for nerve activation, namely high‐speed rotation of a configuration of permanent magnets. Analytical solutions of the cable equation are derived for the oscillating electric field generated, which has amplitude proportional to the rotation speed. The prototype device built comprised a configuration of two cylindrical magnets with antiparallel magnetisations, made to rotate by interaction between the magnets’ own magnetic field and three‐phase currents in coils mounted on one side of the device. The electric field in a rectangular bath placed on top of the device was both numerically evaluated and measured. The ratio of the electric field gradient on frequency was approximately 1 V m−2 Hz−1 near the device. An exploratory series of physiological tests was conducted on the sciatic nerve and attached gastrocnemius muscle of the cane toad

  7. A compact permanent magnet cyclotrino for accelerator mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Young, A.T.; Clark, D.J.; Kunkel, W.B.; Leung, K.N.; Li, C.Y. [Lawrence Berkeley Lab., CA (United States)

    1995-02-01

    The authors describe the development of a new instrument for the detection of trace amounts of rare isotopes, a Cyclotron Mass Spectrometer (CMS). A compact low energy cyclotron optimized for high mass resolution has been designed and has been fabricated. The instrument has high sensitivity and is designed to measure carbon-14 at abundances of < 10{sup {minus}12}. A novel feature of the instrument is the use of permanent magnets to energize the iron poles of the cyclotron. The instrument uses axial injection, employing a spiral inflector. The instrument has been assembled and preliminary measurements of the magnetic field show that it has a uniformity on the order of 2 parts in 10{sup 4}.

  8. Permanent magnet electron cyclotron resonance plasma source with remote window

    International Nuclear Information System (INIS)

    Berry, L.A.; Gorbatkin, S.M.

    1995-01-01

    An electron cyclotron resonance (ECR) plasma has been used in conjunction with a solid metal sputter target for Cu deposition over 200 mm diameters. The goal is to develop a deposition system and process suitable for filling submicron, high-aspect ratio ULSI features. The system uses a permanent magnet for creation of the magnetic field necessary for ECR, and is significantly more compact than systems equipped with electromagnets. A custom launcher design allows remote microwave injection with the microwave entrance window shielded from the copper flux. When microwaves are introduced at an angle with respect to the plasma, high electron densities can be produced with a plasma frequency significantly greater than the electron cyclotron frequency. Copper deposition rates of 1000 A/min have been achieved

  9. An improved iron loss estimation for permanent magnet brushless machines

    CERN Document Server

    Fang, D

    1999-01-01

    This paper presents an improved approach for predicting iron losses in permanent magnet brushless machines. The new approach is based on the fundamental concept that eddy current losses are proportional to the square of the time rate of change of flux density. Expressions are derived for predicting hysteresis and eddy current losses in the stator teeth and yoke. The so-called anomalous or excess losses, caused by the induced eddy current concentration around moving magnetic domain walls and neglected in the conventional core loss calculation, are also included in the proposed approach. In addition, the model is also capable of accounting for the stator skewing, if present. The core losses obtained from the proposed approach are compared with those measured on an existing PM motor at several operating speeds, showing very good agreement. (14 refs).

  10. Analysis and optimization of hybrid excitation permanent magnet synchronous generator for stand-alone power system

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Huijun, E-mail: huijun024@gmail.com [School of Instrumentation Science and Opto-electronics Engineering, Beihang University (China); Qu, Zheng; Tang, Shaofei; Pang, Mingqi [School of Instrumentation Science and Opto-electronics Engineering, Beihang University (China); Zhang, Mingju [Shanghai Aerospace Control Technology Institute, Shanghai (China)

    2017-08-15

    Highlights: • One novel permanent magnet generator structure has been proposed to reduce voltage regulation ratio. • Finite element method and equivalent circuit methods are both employed to realize rapid generator design. • Design of experiment (DOE) method is used to optimize permanent magnet shape for reduce voltage waveform distortion. • The obtained analysis and experiment results verify the proposed design methods. - Abstract: In this paper, electromagnetic design and permanent magnet shape optimization for permanent magnet synchronous generator with hybrid excitation are investigated. Based on generator structure and principle, design outline is presented for obtaining high efficiency and low voltage fluctuation. In order to realize rapid design, equivalent magnetic circuits for permanent magnet and iron poles are developed. At the same time, finite element analysis is employed. Furthermore, by means of design of experiment (DOE) method, permanent magnet is optimized to reduce voltage waveform distortion. Finally, the validity of proposed design methods is validated by the analytical and experimental results.

  11. Analysis and optimization of hybrid excitation permanent magnet synchronous generator for stand-alone power system

    International Nuclear Information System (INIS)

    Wang, Huijun; Qu, Zheng; Tang, Shaofei; Pang, Mingqi; Zhang, Mingju

    2017-01-01

    Highlights: • One novel permanent magnet generator structure has been proposed to reduce voltage regulation ratio. • Finite element method and equivalent circuit methods are both employed to realize rapid generator design. • Design of experiment (DOE) method is used to optimize permanent magnet shape for reduce voltage waveform distortion. • The obtained analysis and experiment results verify the proposed design methods. - Abstract: In this paper, electromagnetic design and permanent magnet shape optimization for permanent magnet synchronous generator with hybrid excitation are investigated. Based on generator structure and principle, design outline is presented for obtaining high efficiency and low voltage fluctuation. In order to realize rapid design, equivalent magnetic circuits for permanent magnet and iron poles are developed. At the same time, finite element analysis is employed. Furthermore, by means of design of experiment (DOE) method, permanent magnet is optimized to reduce voltage waveform distortion. Finally, the validity of proposed design methods is validated by the analytical and experimental results.

  12. Analysis and design of permanent magnet biased magnetic bearing based on hybrid factor

    Directory of Open Access Journals (Sweden)

    Jinji Sun

    2016-03-01

    Full Text Available In this article, hybrid factor is proposed for hybrid magnetic bearing. The hybrid factor is defined as the ratio of the force produced by the permanent magnet and the forces produced by the permanent magnet and current in hybrid magnetic bearing. It is deduced from a certain radial hybrid magnetic bearing using its important parameters such as the current stiffness and displacement stiffness at first and then the dynamic model of magnetically suspended rotor system is established. The relationship between structural parameters and control system parameters is analyzed based on the hybrid factor. Some influencing factors of hybrid factor in hybrid magnetic bearing, such as the size of the permanent magnet, length of air gap, and area of the stator poles, are analyzed in this article. It can be concluded that larger hybrid factor can be caused by the smaller power loss according to the definition of hybrid factor mentioned above. Meanwhile, the hybrid factor has a maximum value, which is related to control system parameters such as proportional factor expect for structural parameters. Finally, the design steps of parameters of hybrid magnetic bearing can be concluded.

  13. Direct current force sensing device based on compressive spring, permanent magnet, and coil-wound magnetostrictive/piezoelectric laminate.

    Science.gov (United States)

    Leung, Chung Ming; Or, Siu Wing; Ho, S L

    2013-12-01

    A force sensing device capable of sensing dc (or static) compressive forces is developed based on a NAS106N stainless steel compressive spring, a sintered NdFeB permanent magnet, and a coil-wound Tb(0.3)Dy(0.7)Fe(1.92)/Pb(Zr, Ti)O3 magnetostrictive∕piezoelectric laminate. The dc compressive force sensing in the device is evaluated theoretically and experimentally and is found to originate from a unique force-induced, position-dependent, current-driven dc magnetoelectric effect. The sensitivity of the device can be increased by increasing the spring constant of the compressive spring, the size of the permanent magnet, and/or the driving current for the coil-wound laminate. Devices of low-force (20 N) and high-force (200 N) types, showing high output voltages of 262 and 128 mV peak, respectively, are demonstrated at a low driving current of 100 mA peak by using different combinations of compressive spring and permanent magnet.

  14. Analysis and optimization of hybrid excitation permanent magnet synchronous generator for stand-alone power system

    Science.gov (United States)

    Wang, Huijun; Qu, Zheng; Tang, Shaofei; Pang, Mingqi; Zhang, Mingju

    2017-08-01

    In this paper, electromagnetic design and permanent magnet shape optimization for permanent magnet synchronous generator with hybrid excitation are investigated. Based on generator structure and principle, design outline is presented for obtaining high efficiency and low voltage fluctuation. In order to realize rapid design, equivalent magnetic circuits for permanent magnet and iron poles are developed. At the same time, finite element analysis is employed. Furthermore, by means of design of experiment (DOE) method, permanent magnet is optimized to reduce voltage waveform distortion. Finally, the validity of proposed design methods is validated by the analytical and experimental results.

  15. Magnetic and Engineering Analysis of an Adjustable Strength Permanent Magnet Quadrupole

    CERN Document Server

    Gottschalk, Stephen C

    2005-01-01

    Magnetic and engineering analyses used in the design of an adjustable strength permanent magnet quadrupole will be reported. The quadrupole designed has a pole length of 42cm, aperture diameter 13mm, peak pole tip strength 1.03Tesla and peak integrated gradient * length (GL) of 68.7Tesla. Analyses of magnetic strength, field quality, magnetic centerline, temperature compensation and dynamic eddy currents induced during field adjustments will be presented. Magnet sorting strategies, pole positioning sensitivity, component forces, and other sensitivity analyses will be presented. Engineering analyses of stress, deflection and thermal effects as well as compensation strategies will also be shown.

  16. A new nonlinear magnetic circuit model for dynamic analysis of interior permanent magnet synchronous motor

    International Nuclear Information System (INIS)

    Nakamura, Kenji; Saito, Kenichi; Watanabe, Tadaaki; Ichinokura, Osamu

    2005-01-01

    Interior permanent magnet synchronous motors (IPMSMs) have high efficiency and torque, since the motors can utilize reluctance torque in addition to magnet torque. The IPMSMs are widely used for electric household appliances and electric bicycles and vehicles. A quantitative analysis method of dynamic characteristics of the IPMSMs, however, has not been clarified fully. For optimum design, investigation of dynamic characteristics considering magnetic nonlinearity is needed. This paper presents a new nonlinear magnetic circuit model of an IPMSM, and suggests a dynamic analysis method using the proposed magnetic circuit model

  17. The analysis of the permanent magnet motor using the new magnetic field analysis

    International Nuclear Information System (INIS)

    Shimoji, Hiroyasu; Enokizono, Masato; Todaka, Takashi

    2002-01-01

    In this paper iron loss analysis of the permanent magnet motor considering anisotropy of magnetic material is carried out. Recently the magnetic material can be measured using of vector quantity technique. Non-oriented silicon steel sheets for the iron core material have the anisotropy. Therefore, it is necessary to carry out the analysis considering the anisotropy of the magnetic material. We used the magnetic field analysis, which consider the anisotropy by combining finite element method with the E and S (Enokizono and Soda) modeling. (Author)

  18. The influence of carbon and oxygen on the magnetic characteristics of press-less sintered NdFeB magnets

    Science.gov (United States)

    Xia, M.; Abrahamsen, A. B.; Bahl, C. R. H.; Veluri, B.; Søegaard, A. I.; Bøjsøe, P.; Millot, S.

    2017-01-01

    The Pressless Process (PLP) was adopted to manufacture NdFeB sintered magnets, where the investigations on carbon and oxygen residues from heptane milling liquid media and graphite crucibles used for sintering were quantified to evaluate the influence on the magnetic characteristics. The carbon and oxygen content in the magnets produced from wet ball milling of strip cast flakes was found to be of the order 104 ppm and 4·104 ppm respectively, which resulted in soft magnetic behavior. However using jet milling the carbon and oxygen concentration were decreased by an order of magnitude resulting in coercivity of up to 829 kA/m. Thus the influence of the carbon from the graphite crucibles is small.

  19. Effect of the repulsive force in the HTSC-permanent magnet hybrid bearing system

    International Nuclear Information System (INIS)

    Ohashi, S.; Kobayashi, S.

    2009-01-01

    Magnetic levitation using the pinning force of the YBaCuO high-T c bulk superconductor (HTSC) materials has an advantage to achieve stable levitation without control. To increase levitation force, the HTSC-permanent magnet hybrid magnetic bearing system is introduced. A circular shaped three phase Nd-Fe-B permanent magnet is installed on the rotor, and HTSC bulk superconductor is set on the stator. The additional permanent magnet is installed under the HTSC. Repulsive force of the permanent magnet is used for levitation, and pinning force between the HTSC and permanent magnet is used for guidance force of the bearing. In this system, relationship between permanent magnet and the HTSC is important. When repulsive force of the permanent magnet is large, pinning force of superconductor is used to keep the rotor position. As a result, stability for the lateral direction is decreased with hybrid system. For levitation force, effect of the hybrid system is not observed with column HTSC. Compared with the ring HTSC results, the following thing is considered. Because there is no space that flux of one permanent magnet acts on the other one with the column HTSC configuration, interaction between two permanent magnets becomes small.

  20. Permanent magnet working point ripple in synchronous generators

    Directory of Open Access Journals (Sweden)

    Stefan Sjökvist

    2017-04-01

    Full Text Available Permanent magnets (PMs are today widely used in electrical machines of all sorts. With their increase in popularity, the amount of research has increased as well. In this study, the magnetic flux density ripple of the working point of the PMs in a 100 kW PM synchronous generator has been investigated for three different load cases: no load, AC load, and DC load. The PMs will be subjected to a shift in working point as a consequence of the characteristics of the electrical loading. This study is based on finite element method simulations where the ripple of the magnetic flux density in the PMs was recorded at three positions within a PM. The slot harmonic of 7.5 times the electrical frequency (f(el was present in the results for all load cases, but mainly at the surface of the PM, as expected. Results showed an unexpected harmonic of 1.5 f(el, assumed to be an undertone of the slot harmonics. The 6f(el harmonic for the DC load case was significantly higher than for the AC load case and is caused by the current fluctuation during passive rectification. For the studied machine, the added harmonics in the magnetic field due to passive rectification are less than the slot-related harmonics.

  1. Rotational characteristics in the resonance state of the HTSC-permanent magnet hybrid magnetic bearing

    Energy Technology Data Exchange (ETDEWEB)

    Morii, Y.; Sukedai, M. [Kansai University, 3-3-35 Yamate-cho, Suita, Osaka 564-8680 (Japan); Ohashi, S., E-mail: ohashi@kansai-u.ac.jp [Kansai University, 3-3-35 Yamate-cho, Suita, Osaka 564-8680 (Japan)

    2011-11-15

    The hybrid magnetic bearing has been developed. In the hybrid system, effect of the pinning force becomes smaller. Influence of the vibration and the gradient angle in the resonance state is large. The resonance frequency becomes small in the hybrid bearing system. The hybrid magnetic bearing using permanent magnets and the high-Tc bulk superconductor (HTSC) has been developed. Repulsive force of the permanent magnet is introduced to increase the load weight of the magnetic bearing. Effect of the hybrid system has been shown. In this paper, influence of the hybrid system on the dynamic characteristics of the rotor is studied. The rotational characteristics in the mechanical resonance state are studied, and the equivalent magnetic spring coefficient is estimated from the experimental results of the load weight. The resonance frequency is measured by the rotation experiments. The rotor achieves stable levitation even in the resonance state. In the hybrid system, effect of the pinning force becomes smaller than that of the lateral force generated by the repulsive force between the two permanent magnets at the smaller air gap. Thus influence of the lateral vibration and the gradient angle in the resonance state becomes larger at a smaller air gap. The equivalent magnetic spring coefficient becomes also small, and the resonance frequency becomes small in the hybrid bearing system.

  2. Enhancement of magnetic coupling between permanent magnets and bulk superconductors through iron embedding

    International Nuclear Information System (INIS)

    Seki, H.; Kurabayashi, H.; Suzuki, A.; Ikeda, M.; Akiyama, S.; Murakami, M.

    2009-01-01

    Magnetic torque can be transferred without contact through the coupling of permanent magnets (PM) and bulk superconductors (BSC). For this purpose, permanent magnets should have multiple pole configuration like NSNS. The magnitude of the transferable torque depends on the field strength and the gap between PM and BSC. It was found that the torque decays quickly with the gap. In order to enhance the strength of transferable magnetic torque, we prepared bulk Y-Ba-Cu-O superconductors for which Fe bars are embedded. Holes about 1 mm in diameter were mechanically drilled into bulk Y-Ba-Cu-O, and Fe bars about 0.9 mm in diameter were inserted followed by impregnation of Bi-Pb-Sn alloys with low melting points. The composite of Y-Ba-Cu-O and Fe bars attract magnetic fields generated from permanent magnet before cooling, and thereby magnetic coupling will be improved. We have found that the magnetic torque force can be greatly enhanced through iron embedding.

  3. Micromagnetism and the microstructure of high-temperature permanent magnets

    International Nuclear Information System (INIS)

    Goll, D.; Kronmueller, H.; Stadelmaier, H.H.

    2004-01-01

    Sm 2 (Co,Cu,Fe,Zr) 17 permanent magnets with their three-phase precipitation structure (cells, cell walls, and lamellae) show two characteristic features which so far are difficult to interpret but which are the prerequisites for high-temperature applications: (1) The hard magnetic properties only develop during the final step of the three-step annealing procedure consisting of homogenization, isothermal aging, and cooling. (2) Depending on the composition and on the annealing parameters, the temperature dependence of the coercivity can be easily changed from the conventional monotonic to the recent nonmonotonic behavior showing coercivities up to 1 T even at 500 K. The magnetic hardening during cooling is due to the fact that the cell walls order chemically and structurally during the cooling process. From an analysis of electron diffraction patterns of the superimposed structures existing before and after cooling it could be proven that a phase transition from a phase mixture of defective phases 2:17, 2:7, and 5:19 to the ordered 1:5 phase takes place in the cell walls during cooling. The nonmonotonic temperature dependence of the coercivity is narrowly related to the magnetic hardening mechanism which can be either pinning or nucleation and results from the magnetic and microstructural properties of the cell walls. These properties have been determined quantitatively from hysteresis loop measurements and from high-resolution transmission electron microscopy and energy dispersive x-ray analysis. Due to the temperature dependence of the intrinsic magnetic properties, the nonmonotonic temperature dependence of the coercivity is found to be determined by repulsive pinning of domain walls at the cell walls at low temperatures, by attractive pinning of domain walls in the cell walls at intermediate temperatures, and by nucleation at high temperatures. This complex temperature behavior is also reflected in characteristic changes of the angular dependence of the

  4. The Permanent Magnet Operating Mechanism of Double Coil Parallel Driven at a High Speed

    Directory of Open Access Journals (Sweden)

    WEI Xau-Lao

    2017-02-01

    Full Text Available Abstract:Operating mechanism is the main part of breaker,and the quality of breaker will directly influence the safe operation of power system. Because of the continuous improvement requirements of switch,in order to mak this actuator faster and more powerful closing,this paper proposes a double coil parallel driven permanent magnet actuator at a high speed. This paper expounds the working principle of single and double coil parallel driven permanent magnet actuator. It uses Ansoft building model and contrasts test results. In prance we designed and produced the single and double coil parallel driven permanent magnet actuator for experimental study. The simulation and experiment results show that double coil parallel driven permanent magnet actuator,compared with single coil parallel driven permanent magnet actuator,has a better and faster action performance. Thus,the double coil parallel driven permanent magnet actuator achieves a kind of optimization.

  5. Three-dimensional analytical field calculation of pyramidal-frustum shaped permanent magnets

    NARCIS (Netherlands)

    Janssen, J.L.G.; Paulides, J.J.H.; Lomonova, E.

    2009-01-01

    This paper presents a novel method to obtain fully analytical expressions of the magnetic field created by a pyramidal-frustum shaped permanent magnet. Conventional analytical tools only provide expressions for cuboidal permanent magnets and this paper extends these tools to more complex shapes. A

  6. Analysis and Design of Double-sided Air core Linear Servo Motor with Trapezoidal Permanent Magnets

    DEFF Research Database (Denmark)

    Zhang, Yuqiu; Yang, Zilong; Yu, Minghu

    2011-01-01

    In order to reduce the thrust ripple of linear servo system, a double-sided air core permanent magnet linear servo motor with trapezoidal shape permanent magnets (TDAPMLSM) is proposed in this paper. An analytical model of the motor for predicting the magnetic field in the air-gap at no...

  7. Design considerations for permanent magnet direct drive generators for wind energy applications

    NARCIS (Netherlands)

    Jassal, A.K.; Polinder, H.; Damen, M.E.C.; Versteegh, K.

    2012-01-01

    Permanent Magnet Direct Drive (PMDD) generators offer very high force density, high efficiency and low number of components. Due to these advantages, PMDD generators are getting popular in the wind energy industry especially for offshore application. Presence of permanent magnets gives magnetic

  8. Application of a hydrogenation to production of the Nd sub 2 Fe sub 14 B permanent magnet

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Jeon; Park, Choong Nyeon; Choi, Dap Chun [Chonnam National Univ., Kwangju (Republic of Korea)

    1989-12-01

    Powders of bulk ingot of Nd-Fe-B permanent magnet were prepared by a combination of hydrogenation and mechanical milling. In-situ observation revealed that cracks, during hydrogenation, were initiated at the grain bounderies where Nd-rich phases existed and then propagated into the matrix Nd{sub 2}Fe{sub 14}B phase. The powders were aligned and pressed in the hydrided condition and the green compacts were sintered at 1100 deg C for 1 hr, followed by heat treatment at 600 deg C for 1 hr. The maximum value of the (BH){sub max} of 37 MGOe was obtained with the sample which was planetary ball milled for 18 min after the hydrogenation at 13 atm. This value of (BH){sub max} is comparable with that of the magnets produced by mechanical milling only. (Author).

  9. Permanent magnets for production and use of high energy particle beams

    International Nuclear Information System (INIS)

    Halbach, K.

    1985-03-01

    In the last few years, permanent magnet systems have begun to play a dominant role in the generation of synchrotron radiation and the operation of free electron lasers. Similarly, permanent magnets can lead to significant improvements of accelerators and systems that use them. The general conditions are discussed under which one can expect benefits from permanent magnets, and a number of specific applications will be described in detail

  10. Conceptual design of a compact high gradient quadrupole magnet of varying strength using permanent magnets

    Directory of Open Access Journals (Sweden)

    Gautam Sinha

    2018-02-01

    Full Text Available A concept is presented to design magnets using cylindrical-shaped permanent-magnet blocks, where various types of magnetic fields can be produced by either rotating or varying the size of the magnetic blocks within a given mechanical structure. A general method is introduced to calculate the 3D magnetic field produced by a set of permanent magnets. An analytical expression of the 2D field and the condition to generate various magnetic fields like dipole, quadrupole, and sextupole are derived. Using the 2D result as a starting point, a computer code is developed to get the optimum orientation of the magnets to obtain the user-specific target field profile over a given volume in 3D. Designs of two quadrupole magnets are presented, one using 12 and the other using 24 permanent-magnet blocks. Variation of the quadrupole strength is achieved using tuning coils of a suitable current density and specially designed end tubes. A new concept is introduced to reduce the integrated quadrupole field strength by inserting two hollow cylindrical tubes made of iron, one at each end. This will not affect the field gradient at the center but reduce the integrated field strength by shielding the magnetic field near the ends where the tubes are inserted. The advantages of this scheme are that it is easy to implement, the magnetic axis will not shift, and it will prevent interference with nearby devices. Around 40% integrated field variation is achieved using this method in the present example. To get a realistic estimation of the field quality, a complete 3D model using a nonlinear B-H curve is also studied using a finite-element-based computer code. An example to generate around an 80  T/m quadrupole field gradient is also presented.

  11. Conceptual design of a compact high gradient quadrupole magnet of varying strength using permanent magnets

    Science.gov (United States)

    Sinha, Gautam

    2018-02-01

    A concept is presented to design magnets using cylindrical-shaped permanent-magnet blocks, where various types of magnetic fields can be produced by either rotating or varying the size of the magnetic blocks within a given mechanical structure. A general method is introduced to calculate the 3D magnetic field produced by a set of permanent magnets. An analytical expression of the 2D field and the condition to generate various magnetic fields like dipole, quadrupole, and sextupole are derived. Using the 2D result as a starting point, a computer code is developed to get the optimum orientation of the magnets to obtain the user-specific target field profile over a given volume in 3D. Designs of two quadrupole magnets are presented, one using 12 and the other using 24 permanent-magnet blocks. Variation of the quadrupole strength is achieved using tuning coils of a suitable current density and specially designed end tubes. A new concept is introduced to reduce the integrated quadrupole field strength by inserting two hollow cylindrical tubes made of iron, one at each end. This will not affect the field gradient at the center but reduce the integrated field strength by shielding the magnetic field near the ends where the tubes are inserted. The advantages of this scheme are that it is easy to implement, the magnetic axis will not shift, and it will prevent interference with nearby devices. Around 40% integrated field variation is achieved using this method in the present example. To get a realistic estimation of the field quality, a complete 3D model using a nonlinear B -H curve is also studied using a finite-element-based computer code. An example to generate around an 80 T /m quadrupole field gradient is also presented.

  12. Interfacial Phenomena of Magnetic Fluid with Permanent Magnet in a Longitudinally Excited Container

    International Nuclear Information System (INIS)

    Sudo, Seiichi; Wakuda, Hirofumi; Yano, Tetsuya

    2008-01-01

    This paper describes the magnetic fluid sloshing in a longitudinally excited container. Liquid responses of magnetic fluid with a permanent magnet in a circular cylindrical container subject to vertical vibration are investigated. Experiments are performed on a vibration- testing system which provided longitudinal excitation. A cylindrical container made with the acrylic plastic is used in the experiment. A permanent magnet is in the state of floating in a magnetic fluid. The disk-shaped and ring-shaped magnets are examined. The different interfacial phenomena from the usual longitudinal liquid sloshing are observed. It is found that the wave motion frequency of magnetic fluid with a disk-shaped magnet in the container subject to vertical vibration is exactly same that of the excitation. In the case of ring-shaped magnet, the first symmetrical mode of one-half subharmonic response is dominant at lower excitation frequencies. The magnetic fluid disintegration of the free surface was also observed by a high-speed video camera system

  13. Interfacial Phenomena of Magnetic Fluid with Permanent Magnet in a Longitudinally Excited Container

    Science.gov (United States)

    Sudo, Seiichi; Wakuda, Hirofumi; Yano, Tetsuya

    2008-02-01

    This paper describes the magnetic fluid sloshing in a longitudinally excited container. Liquid responses of magnetic fluid with a permanent magnet in a circular cylindrical container subject to vertical vibration are investigated. Experiments are performed on a vibration- testing system which provided longitudinal excitation. A cylindrical container made with the acrylic plastic is used in the experiment. A permanent magnet is in the state of floating in a magnetic fluid. The disk-shaped and ring-shaped magnets are examined. The different interfacial phenomena from the usual longitudinal liquid sloshing are observed. It is found that the wave motion frequency of magnetic fluid with a disk-shaped magnet in the container subject to vertical vibration is exactly same that of the excitation. In the case of ring-shaped magnet, the first symmetrical mode of one-half subharmonic response is dominant at lower excitation frequencies. The magnetic fluid disintegration of the free surface was also observed by a high-speed video camera system.

  14. Investigation of the Capture of Magnetic Particles From High-Viscosity Fluids Using Permanent Magnets.

    Science.gov (United States)

    Garraud, Alexandra; Velez, Camilo; Shah, Yash; Garraud, Nicolas; Kozissnik, Bettina; Yarmola, Elena G; Allen, Kyle D; Dobson, Jon; Arnold, David P

    2016-02-01

    This paper investigates the practicality of using a small, permanent magnet to capture magnetic particles out of high-viscosity biological fluids, such as synovial fluid. Numerical simulations are used to predict the trajectory of magnetic particles toward the permanent magnet. The simulations are used to determine a "collection volume" with a time-dependent size and shape, which determines the number of particles that can be captured from the fluid in a given amount of time. The viscosity of the fluid strongly influences the velocity of the magnetic particles toward the magnet, hence, the collection volume after a given time. In regards to the design of the magnet, the overall size is shown to most strongly influence the collection volume in comparison to the magnet shape or aspect ratio. Numerical results showed good agreement with in vitro experimental magnetic collection results. In the long term, this paper aims to facilitate optimization of the collection of magnetic particle-biomarker conjugates from high-viscosity biological fluids without the need to remove the fluid from a patient.

  15. Fixed-Time Stability Analysis of Permanent Magnet Synchronous Motors with Novel Adaptive Control

    Directory of Open Access Journals (Sweden)

    Maoxing Liu

    2017-01-01

    Full Text Available We firstly investigate the fixed-time stability analysis of uncertain permanent magnet synchronous motors with novel control. Compared with finite-time stability where the convergence rate relies on the initial permanent magnet synchronous motors state, the settling time of fixed-time stability can be adjusted to desired values regardless of initial conditions. Novel adaptive stability control strategy for the permanent magnet synchronous motors is proposed, with which we can stabilize permanent magnet synchronous motors within fixed time based on the Lyapunov stability theory. Finally, some simulation and comparison results are given to illustrate the validity of the theoretical results.

  16. A study on stable levitation of permanent magnet transportation system with coreless linear synchronous motor

    Energy Technology Data Exchange (ETDEWEB)

    Hiwaki, H [Dept. of Electrical and Electronic Engineering, Musashi Inst. of Technology, Tokyo (Japan); Watada, M [Dept. of Electrical and Electronic Engineering, Musashi Inst. of Technology, Tokyo (Japan); Torii, S [Dept. of Electrical and Electronic Engineering, Musashi Inst. of Technology, Tokyo (Japan); Ebihara, D [Dept. of Electrical and Electronic Engineering, Musashi Inst. of Technology, Tokyo (Japan)

    1996-12-31

    In the permanent magnet levitation system, it is impossible to stabilize the motion of the vehicle in both levitation and guidance directions only by permanent magnet. Therefore, the authors proposed the combined system of permanent magnet for levitation and coreless linear synchronous motor (coreless LSM). To design the coreless coils for LSM, the method to calculate the spring coefficient between coreless coil and permanent magnet for LSM is shown. By using this method, the spring coefficients of the three coil arrangements are compared and coreless coil is designed. Furthermore, the authors showed the possibility of stabilizing the motion of the levitation system with coreless LSM. (orig.)

  17. Magnetic Qualification of Permanent Magnet Quadrupoles for CERN’s Linac4

    CERN Document Server

    Buzio, M; Lombardi, A; Mateo, F

    2012-01-01

    This paper summarizes the results of the magnetic measurements done to qualify prototypes and series permanent- magnet quadrupoles for the new Linac4, currently in construction at CERN. The results, obtained with a combination of stretched wire and rotating coil techniques, include the individually tuned integrated field gradient, multipoles, magnetic axis and field direction. These magnets are characterized by a challengingly small 22 mm aperture diameter and we illustrate the methods adopted to guarantee instrument calibration, along with the estimated accuracies of the measured quantities and their impact on beam optics.

  18. Experimental verification and analytical calculation of unbalanced magnetic force in permanent magnet machines

    Directory of Open Access Journals (Sweden)

    Kyung-Hun Shin

    2017-05-01

    Full Text Available In this study, an exact analytical solution based on Fourier analysis is proposed to compute the unbalanced magnetic force in a permanent magnet machine. The magnetic field solutions are obtained by using a magnetic vector potential and by selecting the appropriate boundary conditions. Based on these field solutions, the force characteristics are also determined analytically. All analytical results were extensively validated with nonlinear two-dimensional finite element analysis and experimental results. Using proposed method, we investigated the influence on the UMF according to machine parameters. Therefore, the proposed method should be very useful in initial design and optimization process of PM machines for UMF analysis.

  19. Hybrid permanent magnet quadrupoles for the Recycler Ring at Fermilab

    International Nuclear Information System (INIS)

    Brown, B.C.; Pruss, S.M.; Foster, G.W.; Glass, H.D.; Harding, D.J.; Jackson, G.R.; May, M.R.; Nicol, T.H.; Ostiguy, J.-F.; Schlabach, R.; Volk, J.T.

    1997-10-01

    Hybrid Permanent Magnet Quadrupoles are used in several applications for the Fermilab Recycler Ring and associated beam transfer lines. Most of these magnets use a 0.6096 m long iron shell and provide integrated gradients up to 1.4 T-m/m with an iron pole tip radius of 41.6 mm. A 58.4 mm pole radius design is also required. Bricks of 25. 4 mm thick strontium ferrite supply the flux to the back of the pole to produce the desired gradients (0.6 to 2.75 T/m). For temperature compensation, Ni-Fe alloy strips are interspersed between ferrite bricks to subtract flux in a temperature dependent fashion. Adjustments of the permeance of each pole using iron between the pole and the flux return shell permits the matching of pole potentials. Magnetic potentials of the poles are adjusted to the desired value to achieve the prescribed strength and field uniformity based on rotating coil harmonic measurements. Procurement, fabrication, pole potential adjustment, and measured fields will be reported

  20. Design of permanent magnet quadrupole for LEHIPA DTL

    International Nuclear Information System (INIS)

    Mathew, Jose V.; Rao, S.V.L.S.; Krishnagopal, S.; Singh, P.

    2011-01-01

    The drift tube linac (DTL) of the low energy high intensity proton accelerator (LEHIPA) has been designed to accelerate 30 mA proton beam from 3 MeV to 20 MeV in a distance of around 13 m. A FFDD lattice structure is selected to provide strong transverse focusing, where each drift tube includes one quadrupole magnet. Beam dynamics simulations specified an effective magnet length of 47 mm, maximum field gradient of 47 T/m, and bore aperture of 24 mm. For these specifications, a detailed design of a very thin permanent magnet quadrupole (PMQ) is presented. Four types of PMQ designs have been compared: a 16-segment trapezoidal design in the Halbach configuration, two 16-segment rectangular designs (with and without gaps), and an 8-segment rectangular design. 2D and 3D modeling codes, POISSON and CST Studio suite are used for the design studies. The good field region is calculated based on field gradient deviation in the transverse plane and integral field homogeneity. The very low aspect ratio of these PMQs leads to edge effects, thereby reducing the central field strength. The 3D simulations are used to study these edge effects. (author)

  1. The low-field permanent magnet electrostatic plasma lens

    International Nuclear Information System (INIS)

    Goncharov, A.; Gorshkov, V.; Maslov, V.; Zadorozhny, V.; Brown, I.

    2004-01-01

    We describe the status of ongoing research and development of the electrostatic plasma lens as used for the manipulation of high current broad beams of heavy ions of moderate energy. In some collaborative work at Lawrence Berkeley National Laboratory the lens was used to good effect for carrying out high dose ion implantation processing. In the process of this work a very narrow range of low magnetic field was found for which the ion-optical characteristics of the lens improved markedly. Subsequent theoretical analysis and computer modeling has led to an understanding of this phenomenon. These serendipitous results open up some attractive possibilities for the development of a new compact and low cost plasma lens based on permanent magnets rather than on current-driven field coils surrounding the lens volume. The development of this kind of lens, including both very low noise and minimal spherical aberration effects, may lead to a tool suitable for use in the injection beam lines of high current heavy ion linear accelerators. Here we briefly review the lens fundamentals, some characteristics of focusing heavy ion beams at low magnetic fields, and summarize recent theoretical and experimental developments, with emphasis on the relevance and suitability of the lens for accelerator injection application

  2. Structural and magnetic studies on spark plasma sintered SmCo{sub 5}/Fe bulk nanocomposite magnets

    Energy Technology Data Exchange (ETDEWEB)

    Rama Rao, N.V. [Defence Metallurgical Research Laboratory, Hyderabad 500 058 (India); Gopalan, R. [Defence Metallurgical Research Laboratory, Hyderabad 500 058 (India)]. E-mail: rg_gopy@yahoo.com; Manivel Raja, M. [Defence Metallurgical Research Laboratory, Hyderabad 500 058 (India); Chandrasekaran, V. [Defence Metallurgical Research Laboratory, Hyderabad 500 058 (India); Chakravarty, D. [International Advanced Research Centre for Powder Metallurgy and New Materials, Hyderabad 500 005 (India); Sundaresan, R. [International Advanced Research Centre for Powder Metallurgy and New Materials, Hyderabad 500 005 (India); Ranganathan, R. [Saha Institute of Nuclear Physics, Kolkata 700 064 (India); Hono, K. [National Institute for Materials Science, 1-2-1 Sengen, Tsukuba 305 0047 (Japan)

    2007-05-15

    SmCo{sub 5}+xwt% Fe (x=0, 5 and 10) nanocomposite powders were synthesized by mechanical milling and were consolidated into bulk shape by spark plasma sintering (SPS) technique. The evolution of structure and magnetic properties were systematically investigated in milled powders as well as in SPS samples. A maximum coercivity of 8.9kOe was achieved in spark plasma sintered SmCo{sub 5}+5wt% Fe sample. The exchange spring interaction between the hard and soft magnetic phases was evaluated using {delta}M-H measurements and the analysis revealed that the SPS sample containing 5wt% Fe had a stronger exchange coupling between the magnetic phases than that of the sample with10wt% Fe.

  3. Electron current extraction from a permanent magnet waveguide plasma cathode

    Energy Technology Data Exchange (ETDEWEB)

    Weatherford, B. R.; Foster, J. E. [University of Michigan, Ann Arbor, Michigan 48109 (United States); Kamhawi, H. [NASA Glenn Research Center, Cleveland, Ohio 44135 (United States)

    2011-09-15

    An electron cyclotron resonance plasma produced in a cylindrical waveguide with external permanent magnets was investigated as a possible plasma cathode electron source. The configuration is desirable in that it eliminates the need for a physical antenna inserted into the plasma, the erosion of which limits operating lifetime. Plasma bulk density was found to be overdense in the source. Extraction currents over 4 A were achieved with the device. Measurements of extracted electron currents were similar to calculated currents, which were estimated using Langmuir probe measurements at the plasma cathode orifice and along the length of the external plume. The influence of facility effects and trace ionization in the anode-cathode gap are also discussed.

  4. A double-sided linear primary permanent magnet vernier machine.

    Science.gov (United States)

    Du, Yi; Zou, Chunhua; Liu, Xianxing

    2015-01-01

    The purpose of this paper is to present a new double-sided linear primary permanent magnet (PM) vernier (DSLPPMV) machine, which can offer high thrust force, low detent force, and improved power factor. Both PMs and windings of the proposed machine are on the short translator, while the long stator is designed as a double-sided simple iron core with salient teeth so that it is very robust to transmit high thrust force. The key of this new machine is the introduction of double stator and the elimination of translator yoke, so that the inductance and the volume of the machine can be reduced. Hence, the proposed machine offers improved power factor and thrust force density. The electromagnetic performances of the proposed machine are analyzed including flux, no-load EMF, thrust force density, and inductance. Based on using the finite element analysis, the characteristics and performances of the proposed machine are assessed.

  5. Fuzzy Impulsive Control of Permanent Magnet Synchronous Motors

    International Nuclear Information System (INIS)

    Dong, Li; Shi-Long, Wang; Xiao-Hong, Zhang; Dan, Yang; Hui, Wang

    2008-01-01

    The permanent magnet synchronous motors (PMSMs) may experience chaotic behaviours with systemic parameters falling into a certain area or under certain working conditions, which threaten the secure and stable operation of motor-driven. Hence, it is important to study the methods of controlling or suppressing chaos in PMSMs. In this work, the Takagi–Sugeno (T-S) fuzzy impulsive control model for PMSMs is established via the T-S modelling methodology and impulsive technology. Based on the new model, the control conditions of asymptotical stability and exponential stability for PMSMs have been derived by the Lyapunov method. Finally, an illustrated example is also given to show the effectiveness of the obtained results

  6. Experimental Evaluation of a Motor Integrated Permanent Magnet Gear

    DEFF Research Database (Denmark)

    Rasmussen, Peter Omand; Frandsen, Tommy; Jensen, Kasper Køtter

    2011-01-01

    This paper presents test results of a new motor integrated permanent magnet gear and clarifies a path for future optimizations. The prototype, which fabrication also is described, is initially targeting electrical traction for vehicles. Basic measured parameters in form of back-emf, stall torque...... and inductances are all in line with finite element calculations. However very high rotational losses are present in the prototype and these losses are higher than the calculations. Some of the losses are present due to poor aspects in the fabrication of the prototype, while others are identified to be caused...... by a non optimal diameter/length aspect ratio. The torque density is superior, the copper losses is only a fraction of the copper losses in other traction motors. With the proposed aspects to reduce the rotational losses is it believed that the unit has a great potential....

  7. Control of Permanent Magnet Synchronous Generator for large wind turbines

    DEFF Research Database (Denmark)

    Busca, Cristian; Stan, Ana-Irina; Stanciu, Tiberiu

    2010-01-01

    Direct Torque Control (DTC) and Field Oriented Control (FOC) are the most dominant control strategies used in generators for wind turbines. In this paper both control methods were implemented on a Permanent Magnet Synchronous Generator (PMSG). The variable speed wind turbine with full scale power...... converter topology was chosen for design. Parameters from a 2 MW wind turbine were used for system modeling. All the components of the wind turbine system (WTS), except the DC-link and the grid site converter were implemented in MATLAB/Simulink. The pitch controller was used to limit the output power...... produced by the turbine. DTC and FOC strategies, using SVM were used to control the generator rotor speed. The performance of the two control strategies were compared after different tests have been carried out....

  8. Optimization of Multibrid Permanent-Magnet Wind Generator Systems

    DEFF Research Database (Denmark)

    Chen, Zhe; Li, H.; Polinder, H.

    2009-01-01

    and multibrid wind turbine configurations are obtained, and the suitable ranges of gear ratios for different power ratings are investigated. Finally, the detailed comparisons of themost cost-effective multibridPMgenerator system and the optimized direct-drive PM generator system are also presented and discussed....... The comparative results have shown that the multibrid wind turbine concept appears more cost-effective than the direct-drive concept.......This paper investigates the cost-effective ranges of gearbox ratios and power ratings of multibrid permanent-magnet (PM) wind generator systems by using a design optimization method. First, the analytical model of a multibrid wind turbine concept consisting of a single-stage gearbox and a three...

  9. Dynamics and Stability of Permanent-Magnet Synchronous Motor

    Directory of Open Access Journals (Sweden)

    Ren He

    2017-01-01

    Full Text Available The aim of this article is to explore the dynamic characteristics and stability of the permanent-magnet synchronous motor (PMSM. PMSM equilibrium local stability condition and Hopf  bifurcation condition, pitchfork bifurcation condition, and fold bifurcation condition have been derived by using the Routh-Hurwitz criterion and the bifurcation theory, respectively. Bifurcation curves of the equilibrium with single and double parameters are obtained by continuation method. Numerical simulations not only confirm the theoretical analysis results but also show one kind of codimension-two-bifurcation points of the equilibrium. PMSM, with or without external load, can exhibit rich dynamic behaviors in different parameters regions. It is shown that if unstable equilibrium appears in the parameters regions, the PMSM may not be able to work stably. To ensure the PMSMs work stably, the inherent parameters should be designed in the region which has only one stable equilibrium.

  10. Structural looseness investigation in slow rotating permanent magnet generators

    DEFF Research Database (Denmark)

    Skrimpas, Georgios Alexandros; Mijatovic, Nenad; Sweeney, Christian Walsted

    2016-01-01

    Structural looseness in electric machines is a condition influencing the alignment of the machine and thus the overall bearing health. In this work, assessment of the above mentioned failure mode is tested on a slow rotating (running speed equal to 0.7Hz) permanent magnet generator (PMG), while...... collecting vibration and current data in order to cross-reference the indications from the two monitoring techniques. It is found that electric signature analysis shows no response even when two hold down bolts are untightened, whereas the analysis results from the vibration data exhibit superior performance....... The vibration-based condition indicators with the best response are the stator slot pass frequency, which can be directly related to the cogging torque in PMGs, and the 4th electric frequency harmonic, whose amplitudes increase due to the overall lower structure damping coefficient under looseness...

  11. Tessellated permanent magnet circuits for flow-through, open gradient separations of weakly magnetic materials

    International Nuclear Information System (INIS)

    Moore, Lee R.; Williams, P. Stephen; Chalmers, Jeffrey J.; Zborowski, Maciej

    2017-01-01

    Emerging microfluidic-based cell assays favor label-free red blood cell (RBC) depletion. Magnetic separation of RBC is possible because of the paramagnetism of deoxygenated hemoglobin but the process is slow for open-gradient field configurations. In order to increase the throughput, periodic arrangements of the unit magnets were considered, consisting of commercially available Nd-Fe-B permanent magnets and soft steel flux return pieces. The magnet design is uniquely suitable for multiplexing by magnet tessellation, here meaning the tiling of the magnet assembly cross-sectional plane by periodic repetition of the magnet and the flow channel shapes. The periodic pattern of magnet magnetizations allows a reduction of the magnetic material per channel with minimal distortion of the field cylindrical symmetry inside the magnet apertures. A number of such magnet patterns are investigated for separator performance, size and economy with the goal of designing an open-gradient magnetic separator capable of reducing the RBC number concentration a hundred-fold in 1 mL whole blood per hour. - Highlights: • Simple geometry of commercial, off-the-shelf NdFeB magnet blocks is amenable to generate high fields and open gradients. • Periodic pattern of permanent magnet blocks (tessellation) reduces the number of blocks per separation channel and improves the efficiency of separator design. • Split-flow lateral transport thin (SPLITT) fractionation model predicts 100-fold reduction of red blood cells from 1 mL whole blood sample in 1 h, suitable for laboratory medicine applications.

  12. Tessellated permanent magnet circuits for flow-through, open gradient separations of weakly magnetic materials

    Energy Technology Data Exchange (ETDEWEB)

    Moore, Lee R. [Department of Biomedical Engineering, Cleveland Clinic, 9500 Euclid Ave., Cleveland OH 44195 (United States); Williams, P. Stephen [Cambrian Technologies, Inc., Cleveland, OH (United States); Chalmers, Jeffrey J. [William G. Lowrie Department of Chemical and Biomedical Engineering, The Ohio State University, Columbus 151 W. Woodruff Avenue, OH 43210 (United States); Zborowski, Maciej, E-mail: zborowm@ccf.org [Department of Biomedical Engineering, Cleveland Clinic, 9500 Euclid Ave., Cleveland OH 44195 (United States)

    2017-04-01

    Emerging microfluidic-based cell assays favor label-free red blood cell (RBC) depletion. Magnetic separation of RBC is possible because of the paramagnetism of deoxygenated hemoglobin but the process is slow for open-gradient field configurations. In order to increase the throughput, periodic arrangements of the unit magnets were considered, consisting of commercially available Nd-Fe-B permanent magnets and soft steel flux return pieces. The magnet design is uniquely suitable for multiplexing by magnet tessellation, here meaning the tiling of the magnet assembly cross-sectional plane by periodic repetition of the magnet and the flow channel shapes. The periodic pattern of magnet magnetizations allows a reduction of the magnetic material per channel with minimal distortion of the field cylindrical symmetry inside the magnet apertures. A number of such magnet patterns are investigated for separator performance, size and economy with the goal of designing an open-gradient magnetic separator capable of reducing the RBC number concentration a hundred-fold in 1 mL whole blood per hour. - Highlights: • Simple geometry of commercial, off-the-shelf NdFeB magnet blocks is amenable to generate high fields and open gradients. • Periodic pattern of permanent magnet blocks (tessellation) reduces the number of blocks per separation channel and improves the efficiency of separator design. • Split-flow lateral transport thin (SPLITT) fractionation model predicts 100-fold reduction of red blood cells from 1 mL whole blood sample in 1 h, suitable for laboratory medicine applications.

  13. Force prediction in permanent magnet flat linear motors (abstract)

    International Nuclear Information System (INIS)

    Eastham, J.F.; Akmese, R.

    1991-01-01

    The advent of neodymium iron boron rare-earth permanent magnet material has afforded the opportunity to construct linear machines of high force to weight ratio. The paper describes the design and construction of an axial flux machine and rotating drum test rig. The machine occupies an arc of 45 degree on a drum 1.22 m in diameter. The excitation is provided by blocks of NdFeB material which are skewed in order to minimize the force variations due to slotting. The stator carries a three-phase short-chorded double-layer winding of four poles. The machine is supplied by a PWM inverter the fundamental component of which is phase locked to the rotor position so that a ''dc brushless'' drive system is produced. Electromagnetic forces including ripple forces are measured at supply frequencies up to 100 Hz. They are compared with finite-element analysis which calculates the force variation over the time period. The paper then considers some of the causes of ripple torque. In particular, the force production due solely to the permanent magnet excitation is considered. This has two important components each acting along the line of motion of the machine, one is due to slotting and the other is due to the finite length of the primary. In the practical machine the excitation poles are skewed to minimize the slotting force and the effectiveness of this is confirmed by both results from the experiments and the finite-element analysis. The end effect force is shown to have a space period of twice that of the excitation. The amplitude of this force and its period are again confirmed by practical results

  14. Angular dependence of coercivity in isotropically aligned Nd-Fe-B sintered magnets

    Science.gov (United States)

    Matsuura, Yutaka; Nakamura, Tetsuya; Sumitani, Kazushi; Kajiwara, Kentaro; Tamura, Ryuji; Osamura, Kozo

    2018-05-01

    In order to understand the coercivity mechanism in Nd-Fe-B sintered magnets, the angular dependence of the coercivity of an isotropically aligned Nd15Co1.0B6Febal. sintered magnet was investigated through magnetization measurements using a vibrating sample magnetometer. These results are compared with the angular dependence calculated under the assumption that the magnetization reversal of each grain follows the Kondorskii law or, in other words, the 1/cos θ law for isotropic alignment distributions. The calculated angular dependence of the coercivity agrees very well with the experiment for magnetic fields applied between angles of 0 and 60°, and it is expected that the magnetization reversal occurs in each grain individually followed the 1/cos θ law. In contrast, this agreement between calculation and experiment is not found for anisotropic Nd-Fe-B samples. This implies that the coercivity of the aligned magnets depends upon the de-pinning of the domain walls from pinning sites. When the de-pinning occurs, it is expected that the domain walls are displaced through several grains at once.

  15. Magnetic Glass Ceramics by Sintering of Borosilicate Glass and Inorganic Waste

    OpenAIRE

    Ponsot, In?s M. M. M.; Pontikes, Yiannis; Baldi, Giovanni; Chinnam, Rama K.; Detsch, Rainer; Boccaccini, Aldo R.; Bernardo, Enrico

    2014-01-01

    Ceramics and glass ceramics based on industrial waste have been widely recognized as competitive products for building applications; however, there is a great potential for such materials with novel functionalities. In this paper, we discuss the development of magnetic sintered glass ceramics based on two iron-rich slags, coming from non-ferrous metallurgy and recycled borosilicate glass. The substantial viscous flow of the glass led to dense products for rapid treatments at relatively low te...

  16. Magnetic viscosity, susceptibility and fluctuation fields in sintered NdFeB

    International Nuclear Information System (INIS)

    Tomka, G.J.; Bissell, P.R.; O'Grady, K.; Chantrell, R.W.

    1990-01-01

    Magnetic viscosity and irreversible susceptibility of a sample of anisotropic sintered NdFeB have been measured using a vibrating sample magnetometer. The fluctuation field as a function of local field is found to decrease with increasing demagnetizing field with a dip at the coercivity. This behavior is compared with an existing computer model based on a non-interacting system of fine, uniaxial, randomly oriented particles

  17. Economic viability, applications and limits of efficient permanent magnet motors - Summary and update; Wirtschaftlichkeit, Anwendungen und Grenzen von effizienten Permanent-Magnet-Motoren - Zusammenfassung und Update - Schlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Lindegger, M. [Circle Motor AG, Guemligen (Switzerland); Biner, H.-P.; Evequoz, B. [Hochschule Westschweiz, Delemont (Switzerland); Salathe, D. [Hochschule Luzern Technik und Architektur, Horw (Switzerland)

    2009-06-15

    This final report for the Swiss Federal Office of Energy (SFOE), takes a look at the economic viability, applications and limits of efficient permanent magnet motors. Permanent magnet motors are compared with standard IEC asynchronous motors. In a theoretical part of the report, it is discussed how the increasing size of the motor influences efficiency, weight, volume and power. The results of practical tests carried out on six motors are presented. Three standard motors with varying efficiency were compared with three permanent-magnet motors for the power range around 3 kW. Market-oriented considerations concerning permanent-magnet motors are discussed. Operational criteria for the choice of the type of motor to be used are also examined.

  18. A chiral-based magnetic memory device without a permanent magnet.

    Science.gov (United States)

    Ben Dor, Oren; Yochelis, Shira; Mathew, Shinto P; Naaman, Ron; Paltiel, Yossi

    2013-01-01

    Several technologies are currently in use for computer memory devices. However, there is a need for a universal memory device that has high density, high speed and low power requirements. To this end, various types of magnetic-based technologies with a permanent magnet have been proposed. Recent charge-transfer studies indicate that chiral molecules act as an efficient spin filter. Here we utilize this effect to achieve a proof of concept for a new type of chiral-based magnetic-based Si-compatible universal memory device without a permanent magnet. More specifically, we use spin-selective charge transfer through a self-assembled monolayer of polyalanine to magnetize a Ni layer. This magnitude of magnetization corresponds to applying an external magnetic field of 0.4 T to the Ni layer. The readout is achieved using low currents. The presented technology has the potential to overcome the limitations of other magnetic-based memory technologies to allow fabricating inexpensive, high-density universal memory-on-chip devices.

  19. Magnetic superelevation design of Halbach permanent magnet guideway for high-temperature superconducting maglev

    Science.gov (United States)

    Lei, Wuyang; Qian, Nan; Zheng, Jun; Huang, Huan; Zhang, Ya; Deng, Zigang

    2017-07-01

    To improve the curve negotiating ability of high-temperature superconducting (HTS) maglev system, a special structure of magnetic superelevation for double-pole Halbach permanent magnet guideway (PMG) was designed. The most significant feature of this design is the asymmetrical PMG that forms a slanting magnetic field without affecting the smoothness of the PMG surface. When HTS maglev vehicle runs through curves with magnetic superelevation, the vehicle will slant due to asymmetry in magnetic field and the flux-pinning effect of onboard HTS bulks. At the same time, one component of the levitation force provides a part of the centripetal force that reduces lateral acceleration of the vehicle and thus enhances its curve negotiating ability. Furthermore, the slant angle of magnetic superelevation can be adjusted by changing the materials and the thickness of the added permanent magnets. This magnetic superelevation method, together with orographic uplift, can be applied to different requirements of PMG designs. Besides, the applicability of this method would benefit future development of high-speed HTS maglev system.

  20. Torque characteristics of double-stator permanent magnet synchronous machines

    Directory of Open Access Journals (Sweden)

    Awah Chukwuemeka Chijioke

    2017-12-01

    Full Text Available The torque profile of a double-stator permanent magnet (PM synchronous machine of 90 mm stator diameter having different rotor pole numbers as well as dual excitation is investigated in this paper. The analysis includes a comparative study of the machine’s torque and power-speed curves, static torque and inductance characteristics, losses and unbalanced magnetic force. The most promising flux-weakening potential is revealed in 13- and 7-rotor pole machines. Moreover, the machines having different rotor/stator (Nr/Ns pole combinations of the form Nr = Ns ± 1 have balanced and symmetric static torque waveforms variation with the rotor position in contrast to the machines having Nr = Ns ± 2. Further, the inductance results of the analyzed machines reveal that the machines with odd rotor pole numbers have better fault-tolerant capability than their even rotor pole equivalents. A prototype of the developed double-stator machine having a 13-pole rotor is manufactured and tested for verification.

  1. High speed subfractional HP-motor with permanent magnets

    International Nuclear Information System (INIS)

    Hanitsch, R.; Frenzel, B.

    1998-01-01

    During the last years an increasing demand for small permanent magnet motors can be detected, especially in the fields of medical applications. For heart assist devices there is the request to have small high speed devices operating at low voltage supply with almost no overtemperature. The design of a special hollow shaft motor for the speed range of 15000..25000 rpm and a torque of 4 to 8 mNm will be outlined. The low noise requirements and the high efficiency request lead to a design with an airgap winding. A thermal analysis is also done in order to meet the conditions given by the medical specialists. The features of the prototype will be presented and also the sensorless control strategy will be outlined. Measured and calculated data show good agreement. Focus will be on the magnetic circuit and the thermal behaviour and not on the control aspects of the motor. Specific parameters demonstrate the good quality of the drive system. (orig.)

  2. Topology optimized and 3D printed polymer-bonded permanent magnets for a predefined external field

    Science.gov (United States)

    Huber, C.; Abert, C.; Bruckner, F.; Pfaff, C.; Kriwet, J.; Groenefeld, M.; Teliban, I.; Vogler, C.; Suess, D.

    2017-08-01

    Topology optimization offers great opportunities to design permanent magnetic systems that have specific external field characteristics. Additive manufacturing of polymer-bonded magnets with an end-user 3D printer can be used to manufacture permanent magnets with structures that had been difficult or impossible to manufacture previously. This work combines these two powerful methods to design and manufacture permanent magnetic systems with specific properties. The topology optimization framework is simple, fast, and accurate. It can also be used for the reverse engineering of permanent magnets in order to find the topology from field measurements. Furthermore, a magnetic system that generates a linear external field above the magnet is presented. With a volume constraint, the amount of magnetic material can be minimized without losing performance. Simulations and measurements of the printed systems show very good agreement.

  3. Development of a hybrid bearing using permanent magnets and piezoelectric actuators

    International Nuclear Information System (INIS)

    Park, Jung-Ho; Ham, Young-Bog; Yun, So-Nam; Lee, Hu-Seung

    2010-01-01

    In this study, a hybrid magnetic bearing with permanent magnets and piezoelectric actuators is investigated. First, in this study, a novel concept in which piezoelectric actuators are used to compensate for low stiffness and damping resulting from the unstable characteristics of a passive magnetic bearing using only permanent magnets is proposed. Secondly, the permanent magnets are optimally arranged through an electromagnetic field analysis. Then, the driving amplifier unit and a prototype radial bearing using the proposed concept are fabricated. Finally, basic characteristics, such as the results of an impact test and a rotational runout test with constant speed are investigated and discussed, and experiments using PID control method are conducted.

  4. Effect of axial magnetic field on a 2.45 GHz permanent magnet ECR ion source.

    Science.gov (United States)

    Nakamura, T; Wada, H; Asaji, T; Furuse, M

    2016-02-01

    Herein, we conduct a fundamental study to improve the generation efficiency of a multi-charged ion source using argon. A magnetic field of our electron cyclotron resonance ion source is composed of a permanent magnet and a solenoid coil. Thereby, the axial magnetic field in the chamber can be tuned. Using the solenoid coil, we varied the magnetic field strength in the plasma chamber and measured the ion beam current extracted at the electrode. We observed an approximately three times increase in the Ar(4+) ion beam current when the magnetic field on the extractor-electrode side of the chamber was weakened. From our results, we can confirm that the multi-charged ion beam current changes depending on magnetic field intensity in the plasma chamber.

  5. Effect of axial magnetic field on a 2.45 GHz permanent magnet ECR ion source

    Energy Technology Data Exchange (ETDEWEB)

    Nakamura, T., E-mail: tsubasa@oshima-k.ac.jp; Wada, H.; Furuse, M. [National Institute of Technology, Oshima College, 1091-1 Komatsu, Suouoshima, Oshima, Yamaguchi 742-2193 (Japan); Asaji, T. [National Institute of Technology, Toyama College, 13 Hongo, Toyama 939-8630 (Japan)

    2016-02-15

    Herein, we conduct a fundamental study to improve the generation efficiency of a multi-charged ion source using argon. A magnetic field of our electron cyclotron resonance ion source is composed of a permanent magnet and a solenoid coil. Thereby, the axial magnetic field in the chamber can be tuned. Using the solenoid coil, we varied the magnetic field strength in the plasma chamber and measured the ion beam current extracted at the electrode. We observed an approximately three times increase in the Ar{sup 4+} ion beam current when the magnetic field on the extractor-electrode side of the chamber was weakened. From our results, we can confirm that the multi-charged ion beam current changes depending on magnetic field intensity in the plasma chamber.

  6. The actual problems of the standardization of magnetically hard materials and permanent magnets

    International Nuclear Information System (INIS)

    Kurbatov, P.A.; Podolskiy, I.D.

    1998-01-01

    The standardization of industrial products raises their accordance with functional purpose, contributes to technological developments and the elimination of technical barriers in trade. The progress of the world trade necessitates the certification of permanent magnets and their manufacturing methods. According to ISO/IEC recommendations, the certification standards should contain the clear requirements to operation parameters of products, that can be impartially controlled. The testing procedures should be clearly formulated and assure that the results may be reproduced. This calls for creation of a system of interconnected certification standards: the standard for technical characteristics of prospective commercial magnetically hard materials, the standard specifications for permanent magnets, the standards for typical testing procedures and the standards for metrological assurance of measurements. (orig.)

  7. A Novel Coaxial Magnetic Gear and Its Integration With Permanent-Magnet Brushless Motor

    DEFF Research Database (Denmark)

    Zhang, Xiaoxu; Liu, Xiao; Chen, Zhe

    2016-01-01

    A magnetic geared machine (MGM) is believed to be a promising candidate for high-torque direct-drive application. One of the key issues for developing MGMs is how to resolve the contradiction between the good performance and the complex structure. This paper aims at proposing a novel coaxial...... magnetic gear (CMG), which will not increase the mechanical complexity after integration with a permanent magnet (PM) brushless machine. The prominent feature of the proposed CMG is the introduction of the stator with modulating teeth, which function as the same as the modulating pole...

  8. Induction heating of rotating nonmagnetic billet in magnetic field produced by high-parameter permanent magnets

    Directory of Open Access Journals (Sweden)

    Ivo Doležel

    2014-04-01

    Full Text Available An advanced way of induction heating of nonmagnetic billets is discussed and modeled. The billet rotates in a stationary magnetic field produced by unmoving high-parameter permanent magnets fixed on magnetic circuit of an appropriate shape. The mathematical model of the problem consisting of two coupled partial differential equations is solved numerically, in the monolithic formulation. Computations are carried out using our own code Agros2D based on a fully adaptive higher-order finite element method. The most important results are verified experimentally on our own laboratory device.

  9. Development of 2.45GHz compact ECR ion sources with permanent magnets

    International Nuclear Information System (INIS)

    Tojyo, E.; Ohshiro, Y.; Oyaizu, M.; Shirakabe, Y.

    1993-05-01

    Two kinds of new compact ECR ion sources have been developed by use of permanent magnets only, for the purpose of acceleration tests of the 25.5MHz INS split coaxial RFQ linac and the 50MHz one. Confined magnetic fields of sources are constructed by permanent magnets only. In this paper design parameters, structures, magnetic field distributions and extracted beam properties of these sources are described briefly. (author)

  10. Hydrogen Decrepitation Press-Less Process recycling of NdFeB sintered magnets

    Science.gov (United States)

    Xia, Manlong; Abrahamsen, Asger B.; Bahl, Christian R. H.; Veluri, Badrinath; Søegaard, Allan I.; Bøjsøe, Poul

    2017-11-01

    A Hydrogen Decrepitation Press-Less Process (HD-PLP) recycling method for recycling of anisotropic NdFeB magnets is demonstrated. The method combines hydrogen decrepitation (HD) disintegration of the initial magnet, powder sieving and the Press-Less Process (PLP), where hydride powder is sintered in a graphite mold. Coercivities up to 534 kA/m were obtained in porous samples based on powder size d 100 μm. The coercivity reached Hci = 957 kA/m being 86% of the original N48M material without addition of rare earth elements.

  11. Uniform magnetization reversal in dual main-phase (Ce,Nd)2Fe14B sintered magnets with inhomogeneous microstructure

    International Nuclear Information System (INIS)

    Zhang, Le-le; Li, Zhu-bai; Zhang, Xue-feng; Ma, Qiang; Liu, Yan-li; Li, Yong-feng; Zhao, Qian

    2017-01-01

    The element distribution and the magnetic properties were investigated in (Ce,Nd)–Fe–B sintered magnets prepared by mixing Nd 13.5 Fe 80 B 6.5 and Ce 9 Nd 4.5 Fe 80 B 6.5 powders with different mass ratios. Two main phases exist, but element diffusion is evident, and the chemical composition of the main phase is widely different from that of the master alloy. The Ce element tends to be expelled from the Ce-rich Re 2 Fe 14 B phase. Compared with the Ce-rich main phase, the Nd-rich Re 2 Fe 14 B phase is more stable in structure. Although the microstructure is inhomogeneous and the magnetocrystalline anisotropy is variable, the magnetization reversal is uniform in these dual main-phase magnets, which should ascribe to the existence of the exchange coupling, and magnetization reversal undergoes the nucleation of the reversed domain in irreversible magnetization. It is expected to further improve the coercivity by optimizing the distribution of the Nd-rich main phase in preparing the resource-saving (Ce,Nd) 2 Fe 14 B sintered magnets. (paper)

  12. Influence of End-Effects on Static Torque Performance of Misaligned Cylindrical Permanent Magnet Couplings

    DEFF Research Database (Denmark)

    Högberg, Stig; Hansen, Hilary; Jensen, Bogi Bech

    2014-01-01

    Permanent magnet couplings are widely used in applications requiring torque to be transmitted through an air- gap. The aim of this study is to observe and explain the effect of radial and axial misalignment in a 12-pole, cylindrical permanent magnet coupling. Pull-out torque was measured for two...

  13. Optimal Design of Stator Interior Permanent Magnet Machine with Minimized Cogging Torque for Wind Power Application

    DEFF Research Database (Denmark)

    Chen, Zhe; Zhang, Jianzhong; Cheng, Ming

    2008-01-01

    This paper proposes a new approach to minimize the cogging torque of a stator interior permanent magnet (SIPM) machine. The optimization of stator slot gap and permanent magnet is carried out and the cogging torque ripple is analyzed by using finite element analysis. Experiments on a prototype...

  14. Improved cost of energy comparison of permanent magnet generators for large offshore wind turbines

    NARCIS (Netherlands)

    Hart, K.; McDonald, A.; Polinder, H.; Corr, E.; Carroll, J.

    2014-01-01

    This paper investigates geared and direct-drive permanent magnet generators for a typical offshore wind turbine, providing a detailed comparison of various wind turbine drivetrain configurations in order to minimise the Cost of Energy. The permanent magnet generator topologies considered include a

  15. Torque Analysis With Saturation Effects for Non-Salient Single-Phase Permanent-Magnet Machines

    DEFF Research Database (Denmark)

    Lu, Kaiyuan; Ritchie, Ewen

    2011-01-01

    The effects of saturation on torque production for non-salient, single-phase, permanent-magnet machines are studied in this paper. An analytical torque equation is proposed to predict the instantaneous torque with saturation effects. Compared to the existing methods, it is computationally faster......-element results, and experimental results obtained on a prototype single-phase permanent-magnet machine....

  16. Design and Analysis of a Permanent Magnet Generator for Naval Applications

    Science.gov (United States)

    2005-06-01

    Miller, Design of Brushless Permanent Magnet Motors , Magna Physics Publishing and Clarendon Press, 1994. [19] James L. Kirtley, "Course 6.685: Electric...Kirtley & Edward C. Lovelace, "Drag Loss in Retaining Rings of Permanent Magnet Motors ," SatCon Technology Corporation, March, 2003. [66] H. Polinder

  17. Rotor design of a novel self-start type permanent magnet synchronous motor

    OpenAIRE

    Egawa, T; Higuchi, Tsuyoshi; Yokoi, Yuichi; Abe, T; Miyamoto, Yasuhiro; Ohto, M

    2012-01-01

    Recently, permanent magnet type synchronous motor has been used widely for industry application. In the paper, we propose a novel self-start type permanent magnet synchronous motor with squirrel-cage and analyze the basic characteristics of the motor. We try to increase the efficiency by the rotor design with the finite element analysis.

  18. On the cooling rate of strip cast ingots for sintered NdFeB magnets

    Energy Technology Data Exchange (ETDEWEB)

    Yu, L.Q. [State Key Lab of Silicon Materials, Zhejiang University, Hangzhou 310027 (China); Yan, M. [State Key Lab of Silicon Materials, Zhejiang University, Hangzhou 310027 (China)]. E-mail: mse_yanmi@dial.zju.edu.cn; Wu, J.M. [State Key Lab of Silicon Materials, Zhejiang University, Hangzhou 310027 (China); Luo, W. [State Key Lab of Silicon Materials, Zhejiang University, Hangzhou 310027 (China); Cui, X.G. [State Key Lab of Silicon Materials, Zhejiang University, Hangzhou 310027 (China); Ying, H.G. [State Key Lab of Silicon Materials, Zhejiang University, Hangzhou 310027 (China)

    2007-04-30

    Effects of the cooling rate of strip cast ingots on magnetic properties of sintered NdFeB magnets were studied. It is found that the magnetic properties greatly depend on wheel speed due to different alloy microstructures, which affect readily the particle size distribution of powders obtained after the subsequent jet milling. At higher cooling rate, interlamellar spacing between Nd-rich platelets of the alloy was small, resulting in a lower saturated magnetization due to increased amounts of small particles after jet milling. With further decreasing cooling rate, the resultant larger interlamellar spacing led to too large particle sizes as well as a more irregular shape; thus deteriorated the magnetic properties of the final magnet. A model was developed to disclose the effects of particle sizes on the magnetic alignment process. In the current investigation, optimum magnetic properties of the final magnets were obtained with a cooling rate of 2.6 m/s for preparing the strip. The magnets made by conventionally cast ingot technique exhibited the lowest magnetic properties because of the slowest cooling rate.

  19. Exact analytical modeling of magnetic vector potential in surface inset permanent magnet DC machines considering magnet segmentation

    Science.gov (United States)

    Jabbari, Ali

    2018-01-01

    Surface inset permanent magnet DC machine can be used as an alternative in automation systems due to their high efficiency and robustness. Magnet segmentation is a common technique in order to mitigate pulsating torque components in permanent magnet machines. An accurate computation of air-gap magnetic field distribution is necessary in order to calculate machine performance. An exact analytical method for magnetic vector potential calculation in surface inset permanent magnet machines considering magnet segmentation has been proposed in this paper. The analytical method is based on the resolution of Laplace and Poisson equations as well as Maxwell equation in polar coordinate by using sub-domain method. One of the main contributions of the paper is to derive an expression for the magnetic vector potential in the segmented PM region by using hyperbolic functions. The developed method is applied on the performance computation of two prototype surface inset magnet segmented motors with open circuit and on load conditions. The results of these models are validated through FEM method.

  20. The observation of resistivity change on the ultrasonic treated Fe-Cr ODS sinter alloy under magnetic field influence

    Science.gov (United States)

    Silalahi, Marzuki; Purwanto, Setyo; Mujamilah; Dimyati, Arbi

    2018-03-01

    About the observation of resistivity change on the ultrasonic treated Fe-Cr ODS sinter alloy under magnetic field influence. This paper reported about the observation of the resistivity change in the ultrasonic pre-treated Fe-Cr ODS sinter alloy under the influence of magnetic field at the Center for Science and Technology of Advanced Material, Nuclear Energy Agency of Indonesia. Fe-Cr ODS alloy were sinthesized by vacuum sintering of Fe- and Cr-powder dispersed Y2O3. However, before sintering the powder mixture was subjected to the irradiation process by ultrasonic for 50 hours at 20 kHz and then isostatic pressed up to 50.91 MPa to form a coin of 10 mm in diameter. LCR meassurement revealed the decreasing of resistivity about 3 times by increasing of applied magnetic field from 0 to 70 mT. In addition, VSM meassurement was performed on both as powder material and as sintered sample. The results showed increasing the magnetization with increasing magnetic field and the curve exhibits almost exact symmetry S-form with small hysterese indicating fast changing magnetization and demagnetization capability without energy loss. This opens strong speculations about the existence of magnetoresistant property of the material which is important for many application in field of sensors or electro magnetic valves.

  1. The influence of carbon and oxygen on the magnetic characteristics of press-less sintered NdFeB magnets

    International Nuclear Information System (INIS)

    Xia, M.; Abrahamsen, A.B.; Bahl, C.R.H.; Veluri, B.; Søegaard, A.I.; Bøjsøe, P.; Millot, S.

    2017-01-01

    The Pressless Process (PLP) was adopted to manufacture NdFeB sintered magnets, where the investigations on carbon and oxygen residues from heptane milling liquid media and graphite crucibles used for sintering were quantified to evaluate the influence on the magnetic characteristics. The carbon and oxygen content in the magnets produced from wet ball milling of strip cast flakes was found to be of the order 10 4 ppm and 4·10 4 ppm respectively, which resulted in soft magnetic behavior. However using jet milling the carbon and oxygen concentration were decreased by an order of magnitude resulting in coercivity of up to 829 kA/m. Thus the influence of the carbon from the graphite crucibles is small. - Highlights: • It is found that the carbon from graphite crucibles will not influence the NdFeB. • The carbon from heptane mixed with NdFeB powder will react with the NdFeB, which breaks the magnetic properties of NdFeB. • Pressless process works well with graphite crucibles, without worrying that carbon has damage on magnets.

  2. The influence of carbon and oxygen on the magnetic characteristics of press-less sintered NdFeB magnets

    Energy Technology Data Exchange (ETDEWEB)

    Xia, M., E-mail: maxi@dtu.dk [Department of Energy Conversion and Storage, DTU Risø Campus, Technical University of Denmark, Roskilde (Denmark); Abrahamsen, A.B. [Department of Wind Energy, DTU Risø campus, Technical University of Denmark, Roskilde (Denmark); Bahl, C.R.H. [Department of Energy Conversion and Storage, DTU Risø Campus, Technical University of Denmark, Roskilde (Denmark); Veluri, B.; Søegaard, A.I. [Grundfos A/S, DK-8850 Bjerringbro (Denmark); Bøjsøe, P. [Holm Magnetics APS, 2800 Kongens Lyngby (Denmark); Millot, S. [FJ Industries A/S, 5863 Ferritslev (Denmark)

    2017-01-15

    The Pressless Process (PLP) was adopted to manufacture NdFeB sintered magnets, where the investigations on carbon and oxygen residues from heptane milling liquid media and graphite crucibles used for sintering were quantified to evaluate the influence on the magnetic characteristics. The carbon and oxygen content in the magnets produced from wet ball milling of strip cast flakes was found to be of the order 10{sup 4} ppm and 4·10{sup 4} ppm respectively, which resulted in soft magnetic behavior. However using jet milling the carbon and oxygen concentration were decreased by an order of magnitude resulting in coercivity of up to 829 kA/m. Thus the influence of the carbon from the graphite crucibles is small. - Highlights: • It is found that the carbon from graphite crucibles will not influence the NdFeB. • The carbon from heptane mixed with NdFeB powder will react with the NdFeB, which breaks the magnetic properties of NdFeB. • Pressless process works well with graphite crucibles, without worrying that carbon has damage on magnets.

  3. The design, magnetization and control of a superconducting permanent magnet synchronous motor

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Y; Pei, R; Xian, W; Hong, Z; Coombs, T A [Engineering Department, University of Cambridge, Trumpington Street, Cambridge CB2 1PZ (United Kingdom)], E-mail: yj222@cam.ac.uk

    2008-06-15

    This paper describes in detail the method of magnetization of a superconducting permanent magnet synchronous motor. The rotor of the motor consists of 60 superconducting pucks, which are magnetized by two additional copper windings. The pulse field magnetization (PFM) method is considered and the resulted distribution of the magnetizing flux linkage from the rotor is not a perfect sine wave in the air gap, which leads to a large torque ripple and harmonics of the stator currents. In order to suppress the torque ripple, an iterative learning control (ILC) algorithm is used in addition to the former field-oriented control method. The results show the ILC algorithm can largely reduce the torque ripple.

  4. Rotatable Small Permanent Magnet Array for Ultra-Low Field Nuclear Magnetic Resonance Instrumentation: A Concept Study.

    Science.gov (United States)

    Vogel, Michael W; Giorni, Andrea; Vegh, Viktor; Pellicer-Guridi, Ruben; Reutens, David C

    2016-01-01

    We studied the feasibility of generating the variable magnetic fields required for ultra-low field nuclear magnetic resonance relaxometry with dynamically adjustable permanent magnets. Our motivation was to substitute traditional electromagnets by distributed permanent magnets, increasing system portability. The finite element method (COMSOL®) was employed for the numerical study of a small permanent magnet array to calculate achievable magnetic field strength, homogeneity, switching time and magnetic forces. A manually operated prototype was simulated and constructed to validate the numerical approach and to verify the generated magnetic field. A concentric small permanent magnet array can be used to generate strong sample pre-polarisation and variable measurement fields for ultra-low field relaxometry via simple prescribed magnet rotations. Using the array, it is possible to achieve a pre-polarisation field strength above 100 mT and variable measurement fields ranging from 20-50 μT with 200 ppm absolute field homogeneity within a field-of-view of 5 x 5 x 5 cubic centimetres. A dynamic small permanent magnet array can generate multiple highly homogeneous magnetic fields required in ultra-low field nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) instruments. This design can significantly reduce the volume and energy requirements of traditional systems based on electromagnets, improving portability considerably.

  5. Design and Finite Element Analysis of a Novel Transverse Flux Permanent Magnet Disk Generator

    DEFF Research Database (Denmark)

    Hosseini, Seyedmohsen; Moghani, Javad Shokrollahi; Ershad, Nima Farrokhzad

    2011-01-01

    This paper presents a novel structure of a transverse flux permanent magnet disk generator. The proposed disk shape structure simplifies prototyping by using simple laminated steel sheets in comparison with previous transverse flux structures that employ bent laminations and soft magnetic...... composites. Also the proposed structure has a higher power factor than what has been reported previously for transverse flux permanent magnet structures. After introducing the transverse flux permanent magnet disk generator, the design process is explained and a small power generator is designed...

  6. Study on a magnetic spiral-type wireless capsule endoscope controlled by rotational external permanent magnet

    Energy Technology Data Exchange (ETDEWEB)

    Ye, Bo, E-mail: yebo@hubu.edu.cn [School of Mechanical Science & Engineering, Huazhong University of Science & Technology, Wuhan 430074 (China); School of Computer Science and Information Engineering, HuBei University, Wuhan 430062 (China); Zhang, Wei [Department of Mechanical Engineering, Hubei University of Automotive Technology, Shiyan 442002 (China); Sun, Zhen-jun [School of Mechanical Science & Engineering, Huazhong University of Science & Technology, Wuhan 430074 (China); Guo, Lin [School of Computer Science and Information Engineering, HuBei University, Wuhan 430062 (China); Deng, Chao [School of Mechanical Science & Engineering, Huazhong University of Science & Technology, Wuhan 430074 (China); Chen, Ya-qi [Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030 (China); Zhang, Hong-hai [School of Mechanical Science & Engineering, Huazhong University of Science & Technology, Wuhan 430074 (China); Liu, Sheng [School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072 (China)

    2015-12-01

    In this paper, the authors propose rotating an external permanent magnet (EPM) to manipulate the synchronous rotation of a magnetic spiral-type wireless capsule endoscope (WCE), and the synchronous rotation of the WCE is converted to its translational motion in intestinal tract. In order to preliminarily verify the feasibility of this method, a handheld actuator (HA) controlled by micro controller unit, a magnetic spiral-type WCE and a bracket were fabricated, theoretical analysis and simulations about the control distance of this method were performed, and in ex-vivo tests were examined in porcine small intestine to verify the control distance and control performances of this method. It was demonstrated that this method showed good performances in controlling the translational motion of the magnetic spiral-type WCE, and this method has great potential to be used in clinical application. - Highlights: • A new magnetic control method for spiral-type wireless capsule endoscope is proposed. • Wireless capsule endoscope rotates synchronously with external permanent magnet. • The method controls the wireless capsule endoscope well in porcine small intestine. • Long control distance makes the method may be used in future medical application. • Experimental setup has great advantages: high cost performance and easy operation.

  7. Faceted shell structure in grain boundary diffusion-processed sintered Nd–Fe–B magnets

    Energy Technology Data Exchange (ETDEWEB)

    Seelam, U.M.R.; Ohkubo, T.; Abe, T.; Hirosawa, S.; Hono, K., E-mail: kazuhiro.hono@nims.go.jp

    2014-12-25

    Graphical abstract: The grain boundary diffusion process (GBDP) using a heavy rare earth elements (HRE) such as Dy and Tb is known as an effective method to enhance the coercivity of Nd–Fe–B sintered magnets without reducing remanence. This process has been industrially implemented to manufacture Nd–Fe–B based sintered magnets with high coercivity and high remanence. In this process, Dy is considered to diffuse through grain boundaries (GBs) to form (Nd{sub 1−x}Dy{sub x}){sub 2}Fe{sub 14}B shells surrounding the Nd{sub 2}Fe{sub 14}B grains and the higher anisotropy field of the Dy-rich shell is considered to suppress the nucleation of reverse domains at low magnetic field. Although there are several investigations on the microstructure of HRE GBDP Nd–Fe–B magnets, no paper addressed the origin of the asymmetric formation of HRE rich shells. Based on detailed analysis of facet planes of core/shell interfaces, we propose a mechanism of the faceted core/shell microstructure formation in the GBDP sintered magnets. We believe that this gives new insights on understanding the coercivity enhancement by the GBDP. - Highlights: • Faceting was observed at the interfaces of cores and shells. • The core/shell interfaces are sharp with an abrupt change in Dy concentration. • Meting occurs at the interfaces of metalic Nd-rich/Nd{sub 2}Fe{sub 14}B phases above 685 °C due to eutectic reaction. • Solidification of Dy-enriched liquid phase from 900 °C can result in the shell formation. - Abstract: Dysprosium enriched shell structure formed by the grain boundary diffusion process (GBDP) of a sintered Nd–Fe–B magnet was characterized by using scanning electron microscopy, electron back-scattered diffraction and transmission electron microscopy. Faceted core–shell interfaces with an abrupt change in Dy concentration suggest the Dy-rich shells are formed by the solidification of the liquid phase during cooling from the GBDP temperature. The Nd-rich phases

  8. Faceted shell structure in grain boundary diffusion-processed sintered Nd–Fe–B magnets

    International Nuclear Information System (INIS)

    Seelam, U.M.R.; Ohkubo, T.; Abe, T.; Hirosawa, S.; Hono, K.

    2014-01-01

    Graphical abstract: The grain boundary diffusion process (GBDP) using a heavy rare earth elements (HRE) such as Dy and Tb is known as an effective method to enhance the coercivity of Nd–Fe–B sintered magnets without reducing remanence. This process has been industrially implemented to manufacture Nd–Fe–B based sintered magnets with high coercivity and high remanence. In this process, Dy is considered to diffuse through grain boundaries (GBs) to form (Nd 1−x Dy x ) 2 Fe 14 B shells surrounding the Nd 2 Fe 14 B grains and the higher anisotropy field of the Dy-rich shell is considered to suppress the nucleation of reverse domains at low magnetic field. Although there are several investigations on the microstructure of HRE GBDP Nd–Fe–B magnets, no paper addressed the origin of the asymmetric formation of HRE rich shells. Based on detailed analysis of facet planes of core/shell interfaces, we propose a mechanism of the faceted core/shell microstructure formation in the GBDP sintered magnets. We believe that this gives new insights on understanding the coercivity enhancement by the GBDP. - Highlights: • Faceting was observed at the interfaces of cores and shells. • The core/shell interfaces are sharp with an abrupt change in Dy concentration. • Meting occurs at the interfaces of metalic Nd-rich/Nd 2 Fe 14 B phases above 685 °C due to eutectic reaction. • Solidification of Dy-enriched liquid phase from 900 °C can result in the shell formation. - Abstract: Dysprosium enriched shell structure formed by the grain boundary diffusion process (GBDP) of a sintered Nd–Fe–B magnet was characterized by using scanning electron microscopy, electron back-scattered diffraction and transmission electron microscopy. Faceted core–shell interfaces with an abrupt change in Dy concentration suggest the Dy-rich shells are formed by the solidification of the liquid phase during cooling from the GBDP temperature. The Nd-rich phases are almost free from Dy, and

  9. Effects of Zr alloying on the microstructure and magnetic properties of Alnico permanent magnets

    Science.gov (United States)

    Rehman, Sajjad Ur; Ahmad, Zubair; Haq, A. ul; Akhtar, Saleem

    2017-11-01

    Alnico-8 permanent magnets were produced through casting and subsequent thermal treatment process. Magnetic alloy of nominal composition 32.5 Fe-7.5 Al-1.0 Nb-35.0 Co-4.0 Cu-14.0 Ni-6.0 Ti were prepared by arc melting and casting technique. The Zr was added to 32.5 Fe-7.5 Al-1.0 Nb-35.0 Co-4.0 Cu-14.0 Ni-6.0 Ti alloy ranging from 0.3 to 0.9 wt%. The magnets were developed by employing two different heat treatment cycles known as conventional treatment and thermo-magnetic annealing treatment. The samples were characterized by X-ray diffraction method, Scanning electron microscope and magnetometer by plotting magnetic hysteresis demagnetization curves. The results indicate that magnetic properties are strongly depended upon alloy chemistry and process. The 0.6 wt% Zr added alloys yielded the best magnetic properties among the studied alloys. The magnetic properties obtained through conventional heat treatment are Hc = 1.35 kOe, Br = 5.2 kG and (BH)max = 2 MGOe. These magnetic properties were enhanced to Hc = 1.64 kOe, Br = 6.3 kG and (BH)max = 3.7 MGOe by thermo-magnetic annealing treatment.

  10. Correlations Between Magnetic Flux and Levitation Force of HTS Bulk Above a Permanent Magnet Guideway

    Science.gov (United States)

    Huang, Huan; Zheng, Jun; Zheng, Botian; Qian, Nan; Li, Haitao; Li, Jipeng; Deng, Zigang

    2017-10-01

    In order to clarify the correlations between magnetic flux and levitation force of the high-temperature superconducting (HTS) bulk, we measured the magnetic flux density on bottom and top surfaces of a bulk superconductor while vertically moving above a permanent magnet guideway (PMG). The levitation force of the bulk superconductor was measured simultaneously. In this study, the HTS bulk was moved down and up for three times between field-cooling position and working position above the PMG, followed by a relaxation measurement of 300 s at the minimum height position. During the whole processes, the magnetic flux density and levitation force of the bulk superconductor were recorded and collected by a multipoint magnetic field measurement platform and a self-developed maglev measurement system, respectively. The magnetic flux density on the bottom surface reflected the induced field in the superconductor bulk, while on the top, it reveals the penetrated magnetic flux. The results show that the magnetic flux density and levitation force of the bulk superconductor are in direct correlation from the viewpoint of inner supercurrent. In general, this work is instructive for understanding the connection of the magnetic flux density, the inner current density and the levitation behavior of HTS bulk employed in a maglev system. Meanwhile, this magnetic flux density measurement method has enriched present experimental evaluation methods of maglev system.

  11. A Few Simple Classroom Experiments with a Permanent U-Shaped Magnet

    Science.gov (United States)

    Babovic, Miloš; Babovic, Vukota

    2017-01-01

    A few simple experiments in the magnetic field of a permanent U-shaped magnet are described. Among them, pin oscillations inside the magnet are particularly interesting. These easy to perform and amusing measurements can help pupils understand magnetic phenomena and mutually connect knowledge of various physics branches.

  12. Percussive drilling application of translational motion permanent magnet machine

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Shujun

    2012-07-01

    It is clear that percussive drills are very promising since they can increase the rate of penetration in hard rock formations. Any small improvements on the percussive drills can make a big contribution to lowering the drilling costs since drilling a well for the oil and gas industry is very costly. This thesis presents a percussive drilling system mainly driven by a tubular reciprocating translational motion permanent magnet synchronous motor (RTPMSM), which efficiently converts electric energy to kinetic energy for crushing the hard rock since there is no mechanical media. The thesis starts from state-of-the-art of percussive drilling techniques, reciprocating translational motion motors, and self-sensing control of electric motors and its implementation issues. The following chapters present modeling the hard rock, modeling the drill, the design issues of the drill, the RTPMSM and its control. A single-phase RTPMSM prototype is tested for the hard rock drilling. The presented variable voltage variable frequency control is also validated on it. The space vector control and self-sensing control are also explored on a three-phase RTPMSM prototype. The results show that the percussive drill can be implemented to the hard rock drilling applications. A detailed summarisation of contributions and future work is presented at the end of the thesis.(Author)

  13. Design of High Performance Permanent-Magnet Synchronous Wind Generators

    Directory of Open Access Journals (Sweden)

    Chun-Yu Hsiao

    2014-11-01

    Full Text Available This paper is devoted to the analysis and design of high performance permanent-magnet synchronous wind generators (PSWGs. A systematic and sequential methodology for the design of PMSGs is proposed with a high performance wind generator as a design model. Aiming at high induced voltage, low harmonic distortion as well as high generator efficiency, optimal generator parameters such as pole-arc to pole-pitch ratio and stator-slot-shoes dimension, etc. are determined with the proposed technique using Maxwell 2-D, Matlab software and the Taguchi method. The proposed double three-phase and six-phase winding configurations, which consist of six windings in the stator, can provide evenly distributed current for versatile applications regarding the voltage and current demands for practical consideration. Specifically, windings are connected in series to increase the output voltage at low wind speed, and in parallel during high wind speed to generate electricity even when either one winding fails, thereby enhancing the reliability as well. A PMSG is designed and implemented based on the proposed method. When the simulation is performed with a 6 Ω load, the output power for the double three-phase winding and six-phase winding are correspondingly 10.64 and 11.13 kW. In addition, 24 Ω load experiments show that the efficiencies of double three-phase winding and six-phase winding are 96.56% and 98.54%, respectively, verifying the proposed high performance operation.

  14. Characterization of the ELIMED prototype permanent magnet quadrupole system

    International Nuclear Information System (INIS)

    Russo, A.D.; Schillaci, F.; Romano, F.; Amato, A.; Amico, A.G.; Calanna, A.; Cirrone, G.A.P.; Costa, M.; Cuttone, G.; Amato, C.; Luca, G. De; Gallo, G.; Grmek, A.; Rosa, G. La; Leanza, R.; Pommarel, L.; Flacco, F.A.; Malka, V.; Giove, D.; Maggiore, M.

    2017-01-01

    The system described in this work is meant to be a prototype of a more performing one that will be installed at ELI-Beamlines in Prague for the collection of ions produced after the interaction Laser-target, [1]. It has been realized by the researchers of INFN-LNS (Laboratori Nazionali del Sud of the Instituto Nazionale di Fisica Nucleare) and SIGMAPHI, a French company, using a system of Permanent Magnet Quadrupoles (PMQs), [2]. The final system that will be installed in Prague is designed for protons and carbons up to 60 MeV/u, around 10 times more than the energies involved in the present work. The prototype, shown in this work, has been tested in collaboration with the SAPHIR experimental facility group at LOA (Laboratoire d'Optique Appliqueé) in Paris using a 200 TW Ti:Sapphire laser system. The purpose of this work is to validate the design and the performances of this large and compact bore system and to characterize the beam produced after the interaction laser-target and its features. Moreover, the optics simulations have been compared with a real beam shape on a GAFChromic film. The procedure used during the experimental campaign and the most relevant results are reported here demonstrating a good agreement with the simulations and a good control on the beam optics.

  15. Characterization of the ELIMED prototype permanent magnet quadrupole system

    Science.gov (United States)

    Russo, A. D.; Schillaci, F.; Pommarel, L.; Romano, F.; Amato, A.; Amico, A. G.; Calanna, A.; Cirrone, G. A. P.; Costa, M.; Cuttone, G.; Amato, C.; De Luca, G.; Flacco, F. A.; Gallo, G.; Giove, D.; Grmek, A.; La Rosa, G.; Leanza, R.; Maggiore, M.; Malka, V.; Milluzzo, G.; Petringa, G.; Pipek, J.; Scuderi, V.; Vauzour, B.; Zappalà, E.

    2017-01-01

    The system described in this work is meant to be a prototype of a more performing one that will be installed at ELI-Beamlines in Prague for the collection of ions produced after the interaction Laser-target, [1]. It has been realized by the researchers of INFN-LNS (Laboratori Nazionali del Sud of the Instituto Nazionale di Fisica Nucleare) and SIGMAPHI, a French company, using a system of Permanent Magnet Quadrupoles (PMQs), [2]. The final system that will be installed in Prague is designed for protons and carbons up to 60 MeV/u, around 10 times more than the energies involved in the present work. The prototype, shown in this work, has been tested in collaboration with the SAPHIR experimental facility group at LOA (Laboratoire d'Optique Appliqueé) in Paris using a 200 TW Ti:Sapphire laser system. The purpose of this work is to validate the design and the performances of this large and compact bore system and to characterize the beam produced after the interaction laser-target and its features. Moreover, the optics simulations have been compared with a real beam shape on a GAFChromic film. The procedure used during the experimental campaign and the most relevant results are reported here demonstrating a good agreement with the simulations and a good control on the beam optics.

  16. Review in Transverse Flux Permanent Magnet Generator Design

    Directory of Open Access Journals (Sweden)

    A. Ejlali

    2016-12-01

    Full Text Available Recently, Transverse Flux Permanent Magnet Generators (TFPMGs have been proposed as a possible generator in direct drive variable speed wind turbines due to their unique merits. Generally, the quality of output power in these systems is lower than multi stage fixed speed systems, because of removing the gears, so it’s important to design these kinds of generators with low ripple and lowest harmful harmonics and cogging torque that is one of the most important terms in increasing the quality of output power of generator. The objective of this paper is introducing a simple design method and optimization of high power TFPMG applied in vertical axis direct drive wind turbine system by lowest possible amplitude of cogging torque and highest possible power factor, efficiency and power density.  In order to extract the output values of generator and sensitivity analysis for design and optimization, 3D-Finite element model, has been used. This method has high accuracy and gives us a better insight of generator performance and presents back EMF, cogging torque, flux density and FFT of this TFPMG. This study can help designers in design approach of such motors.

  17. Optimal current waveforms for brushless permanent magnet motors

    Science.gov (United States)

    Moehle, Nicholas; Boyd, Stephen

    2015-07-01

    In this paper, we give energy-optimal current waveforms for a permanent magnet synchronous motor that result in a desired average torque. Our formulation generalises previous work by including a general back-electromotive force (EMF) wave shape, voltage and current limits, an arbitrary phase winding connection, a simple eddy current loss model, and a trade-off between power loss and torque ripple. Determining the optimal current waveforms requires solving a small convex optimisation problem. We show how to use the alternating direction method of multipliers to find the optimal current in milliseconds or hundreds of microseconds, depending on the processor used, which allows the possibility of generating optimal waveforms in real time. This allows us to adapt in real time to changes in the operating requirements or in the model, such as a change in resistance with winding temperature, or even gross changes like the failure of one winding. Suboptimal waveforms are available in tens or hundreds of microseconds, allowing for quick response after abrupt changes in the desired torque. We demonstrate our approach on a simple numerical example, in which we give the optimal waveforms for a motor with a sinusoidal back-EMF, and for a motor with a more complicated, nonsinusoidal waveform, in both the constant-torque region and constant-power region.

  18. Reducing torque ripples in permanent magnet synchronous motor

    Directory of Open Access Journals (Sweden)

    Rihab Abdelmoula

    2017-09-01

    Full Text Available Permanent magnet synchronous motors (PMSMs are exceptionally promising thanks to their many advantages compared with other types of electrical machines. Indeed, PMSMs are characterized by their important torque density, light weight, high air gap flux density, high acceleration, high efficiency and strong power-to-weight ratio. A surface-mounted PMSM (SPMSM is used in this work. The SPMSM is built using a 2D finite element method (FEM. Cogging torque, torque ripples and back-EMF are examined during the design process in order to obtain sinusoidal back-EMF and to minimise torque ripples which are one of the major problems with PMSMs. Two procedures are used to reduce the cogging torque of SPMSM: the effect of slot opening and the influence of skewing the stator laminations. Cogging torque factor tc and the torque ripples factor tr have been calculated to compare the two configurations (open slots and closed slots. Then, the configuration with closed slots is utilised with skewing the stator laminations for different angle 0°, 10° and 15°.

  19. Magnetic and structural properties of spark plasma sintered nanocrystalline NdFeB-powders

    Energy Technology Data Exchange (ETDEWEB)

    Wuest, H., E-mail: holger.wuest@de.bosch.com [Robert Bosch GmbH, Postfach 10 60 50, 70049 Stuttgart (Germany); Bommer, L., E-mail: lars.bommer@de.bosch.com [Robert Bosch GmbH, Postfach 10 60 50, 70049 Stuttgart (Germany); Weissgaerber, T., E-mail: thomas.weissgaerber@ifam-dd.fraunhofer.de [Fraunhofer Institute for Manufacturing Technology and Advanced Materials (IFAM), Branch Lab Dresden, Winterbergstraße 28, 01277 Dresden (Germany); Kieback, B., E-mail: bernd.kieback@ifam-dd.fraunhofer.de [Fraunhofer Institute for Manufacturing Technology and Advanced Materials (IFAM), Branch Lab Dresden, Winterbergstraße 28, 01277 Dresden (Germany); Technische Universität Dresden, Institute for Materials Science, Helmholtzstraße 7, 01069 Dresden (Germany)

    2015-10-15

    Near-stoichiometric NdFeB melt-spun ribbons have been subjected to spark plasma sintering varying the process temperature T{sub SPS} and pressure p{sub SPS} between 600 and 800 °C and 50–300 MPa, respectively. Produced bulk magnets were analyzed regarding microstructure and magnetic properties. For all samples the intrinsic coercivity H{sub c,J} gradually decreases with increasing sintering temperature and pressure, while residual induction B{sub r} increases simultaneously with sample density. Densities close to the theoretical limit were achieved for p{sub SPS}≥90 MPa and T{sub SPS}≥650 °C. With increasing T{sub SPS} precipitations of Nd-rich and Fe-rich phases have been observed as a result of a decomposition of the hard magnetic Nd{sub 2}Fe{sub 14}B phase. Under optimum sintering conditions of p{sub SPS}=300 MPa and T{sub SPS}=650 °C high-density bulk magnets with H{sub c,J}=652 kA/m, B{sub r}=0.86 T and (BH){sub max}=106 kJ/m{sup 3} have been produced. - Highlights: • Consolidation close to the theoretical density for p{sub SPS}≥90 MPa and T{sub SPS}≥650 °C. • Highest (BH){sub max} of 106 kJ/m{sup 3} for p{sub SPS}=300 MPa and T{sub SPS}=650 °C with 98% theo. • H{sub c,J} gradually decreases with increasing T{sub SPS}, while B{sub r} increases simultaneously with. • With increasing T{sub SPS}, Nd- and Fe-rich precipitations are observed. • Reduction in t{sub SPS} is economic but does not increase (BH){sub max} significantly.

  20. Perspectives for high-performance permanent magnets: applications, coercivity, and new materials

    Science.gov (United States)

    Hirosawa, Satoshi; Nishino, Masamichi; Miyashita, Seiji

    2017-03-01

    High-performance permanent magnets are indispensable in the production of high-efficiency motors and generators and ultimately for sustaining the green earth. The central issue of modern permanent magnetism is to realize high coercivity near and above room temperature on marginally hard magnetic materials without relying upon the critical elements such as heavy rare earths by means of nanostructure engineering. Recent investigations based on advanced nanostructure analysis and large-scale first principles calculations have led to significant paradigm shifts in the understandings of coercivity mechanism in Nd-Fe-B permanent magnets, which includes the discovery of the ferromagnetism of the thin (2 nm) intergranular phase surrounding the Nd2Fe14B grains, the occurrence of negative (in-plane) magnetocrystalline anisotropy of Nd ions and some Fe atoms at the interface which degrades coercivity, and visualization of the stochastic behaviors of magnetization in the magnetization reversal process at high temperatures. A major change may occur also in the motor topologies, which is currently overwhelmed by the magnetic flux weakening interior permanent magnet motor type, to other types with variable flux permanent magnet type in some applications to open up a niche for new permanent magnet materials. Keynote talk at 8th International Workshop on Advanced Materials Science and Nanotechnology (IWAMSN2016), 8-12 November 2016, Ha Long City, Vietnam.

  1. Complementary analyses of hollow cylindrical unioriented permanent magnet (HCM) with high permeability external layer

    Science.gov (United States)

    Lobo, Carlos M. S.; Tosin, Giancarlo; Baader, Johann E.; Colnago, Luiz A.

    2017-10-01

    In this article, several studies based on analytical expressions and computational simulations on Hollow Cylindrical Magnets with an external soft ferromagnetic material (HCM magnets) are presented. Electromagnetic configurations, as well as permanent-magnet-based structures, are studied in terms of magnetic field strength and homogeneity. Permanent-magnet-based structures are further analyzed in terms of the anisotropy of the magnetic permeability. It was found that the HCM magnets produce a highly homogeneous magnetic field as long as the magnetic material is isotropic. The dependency of the magnetic field strength and homogeneity in terms of the anisotropy of the magnetic permeability is also explored here. These magnets can potentially be used in medium-resolution NMR spectrometers and high-field NMR spectrometers.

  2. Complementary analyses of hollow cylindrical unioriented permanent magnet (HCM) with high permeability external layer.

    Science.gov (United States)

    Lobo, Carlos M S; Tosin, Giancarlo; Baader, Johann E; Colnago, Luiz A

    2017-10-01

    In this article, several studies based on analytical expressions and computational simulations on Hollow Cylindrical Magnets with an external soft ferromagnetic material (HCM magnets) are presented. Electromagnetic configurations, as well as permanent-magnet-based structures, are studied in terms of magnetic field strength and homogeneity. Permanent-magnet-based structures are further analyzed in terms of the anisotropy of the magnetic permeability. It was found that the HCM magnets produce a highly homogeneous magnetic field as long as the magnetic material is isotropic. The dependency of the magnetic field strength and homogeneity in terms of the anisotropy of the magnetic permeability is also explored here. These magnets can potentially be used in medium-resolution NMR spectrometers and high-field NMR spectrometers. Copyright © 2017 Elsevier Inc. All rights reserved.

  3. The Design of a Device for the Generation of a Strong Magnetic Field in an Air Gap Using Permanent Magnets

    Czech Academy of Sciences Publication Activity Database

    Žežulka, Václav; Straka, Pavel

    2017-01-01

    Roč. 22, č. 2 (2017), s. 250-256 ISSN 1226-1750 Institutional support: RVO:67985891 Keywords : magnet ic field * permanent magnet s * NdFeB magnet s * Halbach arrays Subject RIV: BM - Solid Matter Physics ; Magnet ism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 0.713, year: 2016

  4. Superconducting bulk magnet for maglev vehicle: Stable levitation performance above permanent magnet guideway

    International Nuclear Information System (INIS)

    Deng, Z.; Zheng, J.; Li, J.; Ma, G.; Lu, Y.; Zhang, Y.; Wang, S.; Wang, J.

    2008-01-01

    High-temperature superconducting (HTS) maglev vehicle is well known as one of the most potential applications of bulk high-temperature superconductors (HTSCs) in transported levitation system. Many efforts have promoted the practice of the HTS maglev vehicle in people's life by enhancing the load capability and stability. Besides improving the material performance of bulk HTSC and optimizing permanent magnet guideway (PMG), magnetization method of bulk HTSC is also very effective for more stable levitation. Up to now, applied onboard bulk HTSCs are directly magnetized by field cooling above the PMG for the present HTS maglev test vehicles or prototypes in China, Germany, Russia, Brazil, and Japan. By the direct-field-cooling-magnetization (DFCM) over PMG, maglev performances of the bulk HTSCs are mainly depended on the PMG's magnetic field. However, introducing HTS bulk magnet into the HTS maglev system breaks this dependence, which is magnetized by other non-PMG magnetic field. The feasibility of this HTS bulk magnet for maglev vehicle is investigated in the paper. The HTS bulk magnet is field-cooling magnetized by a Field Control Electromagnets Workbench (FCEW), which produces a constant magnetic field up to 1 T. The levitation and guidance forces of the HTS bulk magnet over PMG with different trapped flux at 15 mm working height (WH) were measured and compared with that by DFCM in the same applied PMG magnetic field at optimal field-cooling height (FCH) 30 mm, WH 15 mm. It is found that HTS bulk magnet can also realize a stable levitation above PMG. The trapped flux of HTS bulk magnet is easily controllable by the charging current of FCEW, which implies the maglev performances of HTS bulk magnet above PMG will be adjustable according to the practical requirement. The more trapped flux HTS bulk magnet will lead to bigger guidance force and smaller repulsion levitation force above PMG. In the case of saturated trapped flux for experimental HTS bulk magnet, it is

  5. Superconducting bulk magnet for maglev vehicle: Stable levitation performance above permanent magnet guideway

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Z.; Zheng, J.; Li, J.; Ma, G.; Lu, Y.; Zhang, Y.; Wang, S. [Applied Superconductivity Laboratory, Southwest Jiaotong University, Chengdu 610031 (China); Wang, J. [Applied Superconductivity Laboratory, Southwest Jiaotong University, Chengdu 610031 (China)], E-mail: jsywang@home.swjtu.edu.cn

    2008-06-15

    High-temperature superconducting (HTS) maglev vehicle is well known as one of the most potential applications of bulk high-temperature superconductors (HTSCs) in transported levitation system. Many efforts have promoted the practice of the HTS maglev vehicle in people's life by enhancing the load capability and stability. Besides improving the material performance of bulk HTSC and optimizing permanent magnet guideway (PMG), magnetization method of bulk HTSC is also very effective for more stable levitation. Up to now, applied onboard bulk HTSCs are directly magnetized by field cooling above the PMG for the present HTS maglev test vehicles or prototypes in China, Germany, Russia, Brazil, and Japan. By the direct-field-cooling-magnetization (DFCM) over PMG, maglev performances of the bulk HTSCs are mainly depended on the PMG's magnetic field. However, introducing HTS bulk magnet into the HTS maglev system breaks this dependence, which is magnetized by other non-PMG magnetic field. The feasibility of this HTS bulk magnet for maglev vehicle is investigated in the paper. The HTS bulk magnet is field-cooling magnetized by a Field Control Electromagnets Workbench (FCEW), which produces a constant magnetic field up to 1 T. The levitation and guidance forces of the HTS bulk magnet over PMG with different trapped flux at 15 mm working height (WH) were measured and compared with that by DFCM in the same applied PMG magnetic field at optimal field-cooling height (FCH) 30 mm, WH 15 mm. It is found that HTS bulk magnet can also realize a stable levitation above PMG. The trapped flux of HTS bulk magnet is easily controllable by the charging current of FCEW, which implies the maglev performances of HTS bulk magnet above PMG will be adjustable according to the practical requirement. The more trapped flux HTS bulk magnet will lead to bigger guidance force and smaller repulsion levitation force above PMG. In the case of saturated trapped flux for experimental HTS bulk

  6. Permanent magnet electron beam ion source/trap systems with bakeable magnets for improved operation conditions

    International Nuclear Information System (INIS)

    Schmidt, M.; Zschornack, G.; Kentsch, U.; Ritter, E.

    2014-01-01

    The magnetic system of a Dresden electron beam ion source (EBIS) generating the necessary magnetic field with a new type of permanent magnet made of high energy density NdFeB-type material operable at temperatures above 100 °C has been investigated and tested. The employment of such kind of magnets provides simplified operation without the time-consuming installation and de-installation procedures of the magnets for the necessary baking of the ion source after commissioning and maintenance work. Furthermore, with the use of a new magnetization technique the geometrical filling factor of the magnetic Dresden EBIS design could be increased to a filling factor of 100% leading to an axial magnetic field strength of approximately 0.5 T exceeding the old design by 20%. Simulations using the finite element method software Field Precision and their results compared with measurements are presented as well. It could be shown that several baking cycles at temperatures higher than 100 °C did not change the magnetic properties of the setup

  7. Permanent magnet electron beam ion source/trap systems with bakeable magnets for improved operation conditions

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt, M., E-mail: mike.schmidt@dreebit.com [DREEBIT GmbH, 01109 Dresden (Germany); Zschornack, G.; Kentsch, U.; Ritter, E. [Department of Physics, Dresden University of Technology, 01062 Dresden, Germany and Helmholtz-Zentrum Dresden-Rossendorf e.V., Institute of Ion Beam Physics and Materials Research, 01328 Dresden (Germany)

    2014-02-15

    The magnetic system of a Dresden electron beam ion source (EBIS) generating the necessary magnetic field with a new type of permanent magnet made of high energy density NdFeB-type material operable at temperatures above 100 °C has been investigated and tested. The employment of such kind of magnets provides simplified operation without the time-consuming installation and de-installation procedures of the magnets for the necessary baking of the ion source after commissioning and maintenance work. Furthermore, with the use of a new magnetization technique the geometrical filling factor of the magnetic Dresden EBIS design could be increased to a filling factor of 100% leading to an axial magnetic field strength of approximately 0.5 T exceeding the old design by 20%. Simulations using the finite element method software Field Precision and their results compared with measurements are presented as well. It could be shown that several baking cycles at temperatures higher than 100 °C did not change the magnetic properties of the setup.

  8. Permanent magnet electron beam ion source/trap systems with bakeable magnets for improved operation conditions.

    Science.gov (United States)

    Schmidt, M; Zschornack, G; Kentsch, U; Ritter, E

    2014-02-01

    The magnetic system of a Dresden electron beam ion source (EBIS) generating the necessary magnetic field with a new type of permanent magnet made of high energy density NdFeB-type material operable at temperatures above 100 °C has been investigated and tested. The employment of such kind of magnets provides simplified operation without the time-consuming installation and de-installation procedures of the magnets for the necessary baking of the ion source after commissioning and maintenance work. Furthermore, with the use of a new magnetization technique the geometrical filling factor of the magnetic Dresden EBIS design could be increased to a filling factor of 100% leading to an axial magnetic field strength of approximately 0.5 T exceeding the old design by 20%. Simulations using the finite element method software Field Precision and their results compared with measurements are presented as well. It could be shown that several baking cycles at temperatures higher than 100 °C did not change the magnetic properties of the setup.

  9. Magnetic torque transferring study for bulk High-Tc superconductors and permanent magnets

    International Nuclear Information System (INIS)

    Wongsatanawarid, A; Suzuki, A; Seki, H; Murakami, M

    2009-01-01

    The torque transferring mechanism taking place in a superconducting mixer design has been studied. Several coupling magnetic arrangements were investigated for more details in the engineering design. A bulk superconductor sample was used to study the torque forces for various cooling gaps, and the twist angle dependence was also monitored for the rotational stiffness in stability. The experimental data with four permanent magnet configurations have been studied in the present work. The maximum torque forces are summarized for usage of engineering design with various gaps. The torque/gap characteristics for four configurations were also measured for the optimisation of the torque at a designed operating gap.

  10. DSP Based Direct Torque Control of Permanent Magnet Synchronous Motor (PMSM) using Space Vector Modulation (DTC-SVM)

    DEFF Research Database (Denmark)

    Swierczynski, Dariusz; Kazmierkowski, Marian P.; Blaabjerg, Frede

    2002-01-01

    DSP Based Direct Torque Control of Permanent Magnet Synchronous Motor (PMSM) using Space Vector Modulation (DTC-SVM)......DSP Based Direct Torque Control of Permanent Magnet Synchronous Motor (PMSM) using Space Vector Modulation (DTC-SVM)...

  11. Axial magnetic field extraction type microwave ion source with a permanent magnet

    International Nuclear Information System (INIS)

    Ishikawa, Junzo; Takagi, Toshinori

    1984-01-01

    A new type of microwave ion source in which a permanent magnet generates an axially directed magnetic field needed for the electron cyclotron resonance was developed. The electron cyclotron resonance produces a high density plasma in the ion source. A mA-order ion beam can be extracted. Compared with usual microwave ion sources, this source has a distinguished feature in that the axially directed magnetic field is formed by use of a permanent magnet. Shape of magnetic force lines near the ion extraction aperture was carefully investigated. The extracted ion current as a function of the ion extraction voltage was measured. The experimental data are in good agreement with the theoretical line. The ion source can be heated up to 500 deg C, and extraction of the alkaline metal ions is possible. The extracted ion current for various elements are shown in the table. The current density normalized by the proton was 350-650 mA/cm 2 which was nearly equal to the upper limit of the extractable positive ion current density. The plasma density was estimated and was 2 - 3 x 10 12 cm -3 . The mass spectrum of a Cesium ion beam was obtained. A negligible amount of impurities was observed. The emittance diagram of the extracted ion beam was measured. The result shows that a low emittance and high brightness ion source is constructed. (Kato, T.)

  12. Investigation of permanent magnet machines for downhole applications: Design, prototype and testing of a flux-switching permanent magnet machine

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Anyuan

    2011-01-15

    The current standard electrical downhole machine is the induction machine which is relatively inefficient. Permanent magnet (PM) machines, having higher efficiencies, higher torque densities and smaller volumes, have widely employed in industrial applications to replace conventional machines, but few have been developed for downhole applications due to the high ambient temperatures in deep wells and the low temperature stability of PM materials over time. Today, with the development of variable speed drives and the applications of high temperature magnet materials, it is increasingly interesting for oil and gas industries to develop PM machines for downhole applications. Recently, some PM machines applications have been presented for downhole applications, which are normally addressed on certain specific downhole case. In this thesis the focus has been put on the performance investigation of different PM machines for general downhole cases, in which the machine outer diameter is limited to be small by well size, while the machine axial length may be relatively long. The machine reliability is the most critical requirement while high torque density and high efficiency are also desirable. The purpose is to understand how the special constraints in downhole condition affect the performances of different machines. First of all, three basic machine concepts, which are the radial, axial and transverse flux machines, are studied in details by analytical method. Their torque density, efficiency, power factor and power capability are investigated with respect to the machine axial length and pole number. The presented critical performance comparisons of the machines provide an indication of machines best suitable with respect to performance and size for downhole applications. Conventional radial flux permanent magnet (RFPM) machines with the PMs on the rotor can provide high torque density and high efficiency. This type of machine has been suggested for several different

  13. Optimal design method for magnetization directions of a permanent magnet array

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Jae Seok [Center for Information Storage Device, Yonsei University, 262 Seongsanno, Seodaemun-gu, Seoul 120-749 (Korea, Republic of); Yoo, Jeonghoon, E-mail: yoojh@yonsei.ac.k [School of Mechanical Engineering, Yonsei University, 262 Seongsanno, Seodaemun-gu, Seoul 120-749 (Korea, Republic of)

    2010-08-15

    In many magnetic systems, the permanent magnet (PM) pattern has a great influence on their performance. This study proposes a systematic optimization method for designing discrete magnetization directions. While previous works have been mostly dependent on researchers' intuition, the developed method is systematic and can be applied to a two-dimensional PM-type eddy current brake model. The effectiveness of the method is confirmed, where the design's aim is to maximize the braking force on a moving conductor. The sensitivity analysis is accomplished by the adjoint variable method and the sequential linear programming is used as an optimizer. Several optimization results for various conditions through the proposed design method are compared to each other and the optimal magnet configuration for an eddy current brake is suggested.

  14. A tubular hybrid Halbach/axially-magnetized permanent-magnet linear machine

    Directory of Open Access Journals (Sweden)

    Yi Sui

    2017-05-01

    Full Text Available A single-phase tubular permanent-magnet linear machine (PMLM with hybrid Halbach/axially-magnetized PM arrays is proposed for free-piston Stirling power generation system. Machine topology and operating principle are elaborately illustrated. With the sinusoidal speed characteristic of the free-piston Stirling engine considered, the proposed machine is designed and calculated by finite-element analysis (FEA. The main structural parameters, such as outer radius of the mover, radial length of both the axially-magnetized PMs and ferromagnetic poles, axial length of both the middle and end radially-magnetized PMs, etc., are optimized to improve both the force capability and power density. Compared with the conventional PMLMs, the proposed machine features high mass and volume power density, and has the advantages of simple control and low converter cost. The proposed machine topology is applicable to tubular PMLMs with any phases.

  15. A tubular hybrid Halbach/axially-magnetized permanent-magnet linear machine

    Science.gov (United States)

    Sui, Yi; Liu, Yong; Cheng, Luming; Liu, Jiaqi; Zheng, Ping

    2017-05-01

    A single-phase tubular permanent-magnet linear machine (PMLM) with hybrid Halbach/axially-magnetized PM arrays is proposed for free-piston Stirling power generation system. Machine topology and operating principle are elaborately illustrated. With the sinusoidal speed characteristic of the free-piston Stirling engine considered, the proposed machine is designed and calculated by finite-element analysis (FEA). The main structural parameters, such as outer radius of the mover, radial length of both the axially-magnetized PMs and ferromagnetic poles, axial length of both the middle and end radially-magnetized PMs, etc., are optimized to improve both the force capability and power density. Compared with the conventional PMLMs, the proposed machine features high mass and volume power density, and has the advantages of simple control and low converter cost. The proposed machine topology is applicable to tubular PMLMs with any phases.

  16. Permanently magnetized high gradient magnetic air filters for the nuclear industry

    International Nuclear Information System (INIS)

    Watson, J.H.P.

    1995-01-01

    This paper describes the structure and testing of two novel permanently magnetized magnetic filters for fine radioactive material. In the first filter the holes in the filter are left open as capture proceeds which means the pressure drop builds up only slowly. This filter is not suitable for composite particles which can be broken by mechanical forces. The second filter has been changed so as to strongly capture particles composed of fine particles weakly bound together which tend to break when captured. This uses a principle of assisted capture in which coarse particles aid the capture of the fine fragments. These filters have the following characteristics: (1) no external magnet is required, (2) no external power is required, (3) small in size and portable, (4) easily interchangeable, and (5) can be cleaned without demagnetizing by using a magnetic fluid which matches the susceptibility of the captured particles

  17. Effect of sintering pressure on structure and magnetic properties of Zn0.99Ni0.01O bulk samples synthesized under different pressures

    International Nuclear Information System (INIS)

    Wang, Yongqiang; Yuan, Chaosheng; Su, Lei; Wang, Zheng; Hao, Junhong; Ren, Yufen

    2015-01-01

    A series of Zn 0.99 Ni 0.01 O bulk samples were prepared by a coprecipitation method, and then sintered at 600 °C under various pressures from normal pressure(NP) to 3 GPa. The effects of sintering pressure (P S ) on the structure, morphology and magnetic properties of the doping samples were investigated in detail. The XRD and HRTEM results reveal that all samples are of single-phase hexagonal structure. Compared with the sample sintered at normal pressure, the lattice parameters a and c of the samples sintered at high pressures (HP) show a sharply decrease. With the increase of sintering pressure, the particle size gradually increases as well as the particles get closer to each other. At 300 K, the sample sintered at normal pressure shows a superparamagnetic-like behavior, while the samples sintered at high pressures display typical ferromagnetic behaviors. The saturation magnetization of the samples sintered at high pressures is three orders of magnitude larger than that of the one sintered at normal pressure. Our results reveal that an appropriate sintering pressure can tune the magnetic properties of Ni-doped ZnO system by changing the lattice parameters, particle size and inter-particle spacing, which may be helpful to the practical applications. - Highlights: • A series of Zn 0.99 Ni 0.01 O bulk samples were sintered in different pressures. • The lattice constants of the samples sintered at high pressure clearly decrease. • The particle size increases gradually with the increase of sintering pressure. • The samples sintered at different pressures show different magnetic behaviors. • Appropriate sintering pressure can tune the magnetic properties of Zn–Ni–O system

  18. Permanent magnet motor drives with switched stator windings

    Energy Technology Data Exchange (ETDEWEB)

    Nipp, E.

    1999-06-01

    Permanent magnet (PM) motors are today regarded as an interesting solution for a wide range of inverter-fed variable-speed drives. The generally increased interest in these motors has led to many investigations on their feasibility for vehicle propulsion. Consequently, they are also of interest for traction applications which led to the research project that is presented in this thesis. The most important advantages that are expected in comparison to the state of the art asynchronous motors are lower losses and a higher torque density. Often the field weakening speed range is important, but difficult to obtain with PM machines because the inductance in the direction of the magnetization tends to be low. An alternative can be to switch different coils groups of the stator winding into different configurations. This is the central topic of this thesis. Various aspects of the design of PM motor drives are considered with special attention to the requirements for the application of the switched winding concept. The studies were thereby limited to the inner rotor, radial flux topology. It was found that two winding parts per phase, implying four different winding connections, is the only interesting solution. An advantage of switched windings is that the internal voltage of the machine will never exceed the maximum inverter output, which increases the operation safety. Furthermore the machine design can uncompromisingly be optimized for operation below base speed, which means low inductances implying a large air gap length and thick magnets. A problem with switched windings is that circulating currents can occur. To diminish them, a 2/3 magnet covering of the pole surface must be chosen in combination with a non-salient rotor. Moreover it was found that the eddy current losses in the magnets can reach non-negligible levels and must be considered when designing a drive system. The major drawback of switched stator windings is probably the occurrence of torque

  19. Micromagnetic simulation of anisotropic grain boundary diffusion for sintered Nd-Fe-B magnets

    Science.gov (United States)

    Li, W.; Zhou, Q.; Zhao, L. Z.; Wang, Q. X.; Zhong, X. C.; Liu, Z. W.

    2018-04-01

    A systematic investigation on the anisotropic grain boundary diffusion in sintered Nd-Fe-B magnets is carried out by micromagnetic simulation. The results indicate that the critical reason for the anisotropic diffusion effect is not the difference in the amount of Dy diffused along different directions but the macroscopic demagnetizing field. The diffusion parallel to the easy axis from both pole surfaces of the magnet can increase the nucleation fields in the two major regions with large macroscopic demagnetizing fields, where the reverse domains can nucleate easily. As a consequence, the grain boundary diffusion along the directions parallel to the easy axis from two pole surfaces is more effective to improve the coercivity of the magnets than that along other directions. It is also found that, to enhance the coercivity, only a limited diffusion depth is required. The present result is in good agreement with the recent experimental findings.

  20. Production of NdFeB powders by HDDR from sintered magnets

    International Nuclear Information System (INIS)

    Janasi, S.R.; Rodrigues, D.; Landgraf, F.J.G.; Campos, M.F. de

    2010-01-01

    The production of NdFeB powders by the HDDR process from metallic alloys has been widely investigated. Different HD and DR conditions have been used to induce anisotropy and to improve the intrinsic coercivity of the obtained powders. The purpose of this study is to apply the HDDR process in the reprocessing of NdFeB sintered magnet scraps. There were investigated different processing conditions as temperature and time of desorption and recombination (DR). The results of X ray diffraction show the formation of the magnetic phase Nd 2 Fe 14 B in all the investigated conditions. Magnetic measurements by vibrating sample magnetometer indicate that powders with intrinsic coercivity up to 790 kA/m were obtained. (author)

  1. Makeup and uses of a basic magnet laboratory for characterizing high-temperature permanent magnets

    Science.gov (United States)

    Niedra, Janis M.; Schwarze, Gene E.

    1991-01-01

    A set of instrumentation for making basic magnetic measurements was assembled in order to characterize high intrinsic coercivity, rare earth permanent magnets with respect to short term demagnetization resistance and long term aging at temperatures up to 300 C. The major specialized components of this set consist of a 13 T peak field, capacitor discharge pulse magnetizer; a 10 in. pole size, variable gap electromagnet; a temperature controlled oven equipped with iron cobalt pole piece extensions and a removable paddle that carries the magnetization and field sensing coils; associated electronic integrators; and sensor standards for field intensity H and magnetic moment M calibration. A 1 cm cubic magnet sample, carried by the paddle, fits snugly between the pole piece extensions within the electrically heated aluminum oven, where fields up to 3.2 T can be applied by the electromagnet at temperatures up to 300 C. A sample set of demagnetization data for the high energy Sm2Co17 type of magnet is given for temperatures up to 300 C. These data are reduced to the temperature dependence of the M-H knee field and of the field for a given magnetic induction swing, and they are interpreted to show the limits of safe operation.

  2. A Steel Wire Stress Measuring Sensor Based on the Static Magnetization by Permanent Magnets

    Directory of Open Access Journals (Sweden)

    Dongge Deng

    2016-10-01

    Full Text Available A new stress measuring sensor is proposed to evaluate the axial stress in steel wires. Without using excitation and induction coils, the sensor mainly consists of a static magnetization unit made of permanent magnets and a magnetic field measurement unit containing Hall element arrays. Firstly, the principle is illustrated in detail. Under the excitation of the magnetization unit, a spatially varying magnetized region in the steel wire is utilized as the measurement region. Radial and axial magnetic flux densities at different lift-offs in this region are measured by the measurement unit to calculate the differential permeability curve and magnetization curve. Feature parameters extracted from the curves are used to evaluate the axial stress. Secondly, the special stress sensor for Φ5 and Φ7 steel wires is developed accordingly. At last, the performance of the sensor is tested experimentally. Experimental results show that the sensor can measure the magnetization curve accurately with the error in the range of ±6%. Furthermore, the obtained differential permeability at working points 1200 A/m and 10000 A/m change almost linearly with the stress in steel wires, the goodness of linear fits are all higher than 0.987. Thus, the proposed steel wire stress measuring sensor is feasible.

  3. Roles of coercivity and remanent flux density of permanent magnet in interior permanent magnet synchronous motor (IPMSM) performance for electric vehicle applications

    Science.gov (United States)

    Won, Hoyun; Hong, Yang-Ki; Lee, Woncheol; Choi, Minyeong

    2018-05-01

    We used four rotor topologies of an interior permanent magnet synchronous motor (IPMSM) to investigate the effects of remanent flux density (Br) and coercivity (Hc) of permanent magnet on motor performance. Commercial strontium hexaferrite (SrFe12O19: energy product, (BH)max, of 4.62 MGOe) and Nd-Fe-B ((BH)max of 38.2 MGOe) magnets were used for the rotor designs. The same machine specifications and magnet volume keep constant, while the Hc and Br vary to calculate torque and energy efficiency with the finite-element analysis. A combination of high Hc and low Br more effectively increased maximum torque of IPMSM when the hexaferrite magnet was used. For Nd-Fe-B magnet, the same combination did not affect maximum torque, but increased energy efficiency at high speed. Therefore, the Hc value of a permanent magnet is more effective than the Br in producing high maximum torque for SrM-magnet based IPMSM and high energy efficiency at high speed for Nd-Fe-B magnet based IPMSM.

  4. Brushed permanent magnet DC MLC motor operation in an external magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Yun, J.; St Aubin, J.; Rathee, S.; Fallone, B. G. [Department of Physics, University of Alberta, 11322-89 Avenue, Edmonton, Alberta T6G 2G7 (Canada) and Department of Oncology, Medical Physics Division, University of Alberta, 11560 University Avenue, Edmonton, Alberta T6G 1Z2 (Canada); Department of Medical Physics, Cross Cancer Institute, 11560 University Avenue, Edmonton, Alberta T6G 1Z2 (Canada) and Department of Oncology, Medical Physics Division, University of Alberta, 11560 University Avenue, Edmonton, Alberta T6G 1Z2 (Canada); Department of Physics, University of Alberta, 11322-89 Avenue, Edmonton, Alberta T6G 2G7 (Canada); Department of Medical Physics, Cross Cancer Institute, 11560 University Avenue, Edmonton, Alberta T6G 1Z2 (Canada) and Department of Oncology, Medical Physics Division, University of Alberta, 11560 University Avenue, Edmonton, Alberta T6G 1Z2 (Canada)

    2010-05-15

    Purpose: Linac-MR systems for real-time image-guided radiotherapy will utilize the multileaf collimators (MLCs) to perform conformal radiotherapy and tumor tracking. The MLCs would be exposed to the external fringe magnetic fields of the linac-MR hybrid systems. Therefore, an experimental investigation of the effect of an external magnetic field on the brushed permanent magnet DC motors used in some MLC systems was performed. Methods: The changes in motor speed and current were measured for varying external magnetic field strengths up to 2000 G generated by an EEV electromagnet. These changes in motor characteristics were measured for three orientations of the motor in the external magnetic field, mimicking changes in motor orientations due to installation and/or collimator rotations. In addition, the functionality of the associated magnetic motor encoder was tested. The tested motors are used with the Varian 120 leaf Millennium MLC (Maxon Motor half leaf and full leaf motors) and the Varian 52 leaf MKII MLC (MicroMo Electronics leaf motor) including a carriage motor (MicroMo Electronics). Results: In most cases, the magnetic encoder of the motors failed prior to any damage to the gearbox or the permanent magnet motor itself. This sets an upper limit of the external magnetic field strength on the motor function. The measured limits of the external magnetic fields were found to vary by the motor type. The leaf motor used with a Varian 52 leaf MKII MLC system tolerated up to 450{+-}10 G. The carriage motor tolerated up to 2000{+-}10 G field. The motors used with the Varian 120 leaf Millennium MLC system were found to tolerate a maximum of 600{+-}10 G. Conclusions: The current Varian MLC system motors can be used for real-time image-guided radiotherapy coupled to a linac-MR system, provided the fringe magnetic fields at their locations are below the determined tolerance levels. With the fringe magnetic fields of linac-MR systems expected to be larger than the

  5. Brushed permanent magnet DC MLC motor operation in an external magnetic field.

    Science.gov (United States)

    Yun, J; St Aubin, J; Rathee, S; Fallone, B G

    2010-05-01

    Linac-MR systems for real-time image-guided radiotherapy will utilize the multileaf collimators (MLCs) to perform conformal radiotherapy and tumor tracking. The MLCs would be exposed to the external fringe magnetic fields of the linac-MR hybrid systems. Therefore, an experimental investigation of the effect of an external magnetic field on the brushed permanent magnet DC motors used in some MLC systems was performed. The changes in motor speed and current were measured for varying external magnetic field strengths up to 2000 G generated by an EEV electromagnet. These changes in motor characteristics were measured for three orientations of the motor in the external magnetic field, mimicking changes in motor orientations due to installation and/or collimator rotations. In addition, the functionality of the associated magnetic motor encoder was tested. The tested motors are used with the Varian 120 leaf Millennium MLC (Maxon Motor half leaf and full leaf motors) and the Varian 52 leaf MKII MLC (MicroMo Electronics leaf motor) including a carriage motor (MicroMo Electronics). In most cases, the magnetic encoder of the motors failed prior to any damage to the gearbox or the permanent magnet motor itself. This sets an upper limit of the external magnetic field strength on the motor function. The measured limits of the external magnetic fields were found to vary by the motor type. The leaf motor used with a Varian 52 leaf MKII MLC system tolerated up to 450 +/- 10 G. The carriage motor tolerated up to 2000 +/- 10 G field. The motors used with the Varian 120 leaf Millennium MLC system were found to tolerate a maximum of 600 +/- 10 G. The current Varian MLC system motors can be used for real-time image-guided radiotherapy coupled to a linac-MR system, provided the fringe magnetic fields at their locations are below the determined tolerance levels. With the fringe magnetic fields of linac-MR systems expected to be larger than the tolerance levels determined, some form of

  6. Brushed permanent magnet DC MLC motor operation in an external magnetic field

    International Nuclear Information System (INIS)

    Yun, J.; St Aubin, J.; Rathee, S.; Fallone, B. G.

    2010-01-01

    Purpose: Linac-MR systems for real-time image-guided radiotherapy will utilize the multileaf collimators (MLCs) to perform conformal radiotherapy and tumor tracking. The MLCs would be exposed to the external fringe magnetic fields of the linac-MR hybrid systems. Therefore, an experimental investigation of the effect of an external magnetic field on the brushed permanent magnet DC motors used in some MLC systems was performed. Methods: The changes in motor speed and current were measured for varying external magnetic field strengths up to 2000 G generated by an EEV electromagnet. These changes in motor characteristics were measured for three orientations of the motor in the external magnetic field, mimicking changes in motor orientations due to installation and/or collimator rotations. In addition, the functionality of the associated magnetic motor encoder was tested. The tested motors are used with the Varian 120 leaf Millennium MLC (Maxon Motor half leaf and full leaf motors) and the Varian 52 leaf MKII MLC (MicroMo Electronics leaf motor) including a carriage motor (MicroMo Electronics). Results: In most cases, the magnetic encoder of the motors failed prior to any damage to the gearbox or the permanent magnet motor itself. This sets an upper limit of the external magnetic field strength on the motor function. The measured limits of the external magnetic fields were found to vary by the motor type. The leaf motor used with a Varian 52 leaf MKII MLC system tolerated up to 450±10 G. The carriage motor tolerated up to 2000±10 G field. The motors used with the Varian 120 leaf Millennium MLC system were found to tolerate a maximum of 600±10 G. Conclusions: The current Varian MLC system motors can be used for real-time image-guided radiotherapy coupled to a linac-MR system, provided the fringe magnetic fields at their locations are below the determined tolerance levels. With the fringe magnetic fields of linac-MR systems expected to be larger than the tolerance

  7. The overview and history of permanent magnet devices in accelerator technology

    International Nuclear Information System (INIS)

    Kraus, R.H.

    1994-01-01

    This paper looks at the early history of accelerator development with a particular focus on the important discoveries that opened the door for the application of permanent-magnet materials to this area of science. Researchers began to use permanent-magnet materials in particle accelerators soon after the invention of the alternating gradient principle, that showed magnetic fields could be used to control the transverse envelope of charged-particle beams. Since that time, permanent-magnet materials have found wide application in the modern charged particle accelerator. A brief history of permanent-magnet use in accelerator physics and technology is outlined, some of the general design considerations are presented, and several material properties of concern for particle accelerator applications are discussed

  8. The overview and history of permanent magnet devices in accelerator technology

    International Nuclear Information System (INIS)

    Kraus, R.H. Jr.

    1993-01-01

    This paper reviews the early history of accelerator development with a particular focus on the important discoveries that opened the door for the application of permanent-magnet materials to this area of science. Researchers began to use permanent-magnet materials in particle accelerators soon after the invention of the alternating gradient principle, that showed magnetic fields could be used to control the transverse envelope of charged-particle beams. Since that time, permanent-magnet materials have found wide application in the modern charged particle accelerator. The history of permanent-magnet use in accelerator physics and technology is outlined, general design considerations are presented, and material properties of concern for particle accelerator applications are discussed

  9. Microstructure, magnetic and Moessbauer studies on spark-plasma sintered Sm-Co-Fe/Fe(Co) nanocomposite magnets

    Energy Technology Data Exchange (ETDEWEB)

    Rao, N V Rama; Saravanan, P; Gopalan, R; Raja, M Manivel; Rao, D V Sreedhara; Chandrasekaran, V [Defence Metallurgical Research Laboratory, Hyderabad-500 058 (India); Sivaprahasam, D [International Advanced Research Centre for Powder Metallurgy and New Materials Hyderabad-500 005 (India); Ranganathan, R [Saha Institute of Nuclear Physics, Kolkata-700 064 (India)], E-mail: rg_gopy@yahoo.com

    2008-03-21

    Nanocomposite powders comprising Sm-Co-Fe intermetallic phases and Fe(Co) were synthesized by high-energy ball milling and were consolidated into bulk magnets by the spark-plasma sintering (SPS) technique. While the microstructure of the SPS samples was characterized by transmission electron microscopy (TEM), the solubility of Fe in different phases was investigated using Moessbauer spectroscopy. TEM studies revealed that the spark-plasma sintered sample has Sm(Co,Fe){sub 5} as a major phase with Sm{sub 2}(Co,Fe){sub 17}, Sm(Co,Fe){sub 2} and Fe(Co) as secondary phases. The size of the nanocrystalline grains of all these phases was found to be in the range 50-100 nm. The Moessbauer spectra of the as-milled powders exhibited two different subspectra: a sextet corresponding to the Fe phase and a broad sextet associated with the Fe(Co) phase; while that of the SPS sample showed four different subspectra: a sextet corresponding to Fe and other three sextets corresponding to the Fe(Co), Sm(Co,Fe){sub 5} and Sm{sub 2}(Co,Fe){sub 17} phases; these results are in accordance with the TEM observation. Recoil magnetization and reversible susceptibility measurements revealed magnetically single phase behaviour of the SPS magnets.

  10. Analysis of a 3-phase tubular permanent magnet linear generator

    Energy Technology Data Exchange (ETDEWEB)

    Nor, K.M.; Arof, H.; Wijono [Malaya Univ., Kuala Lumpur (Malaysia). Faculty of Engineering

    2005-07-01

    A 3-phase tubular permanent linear generator design was described. The generator was designed to be driven by a single or a double 2-stroke combustion linear engine. Combustion took place alternately between 2 opposed chambers. In the single combustion engine, one of the combustion chambers was replaced by a kickback mechanism. The force on the translator generated by the explosion in the combustion chamber was used to compress the air in the kickback chamber. The pressed air was then used to release the stored energy to push back the translator in the opposite direction. The generator was modelled as a 2D object. A parametric simulation was performed to give a series of discrete data required to calculate machine electrical parameters; flux distribution; coil flux linkage; and, cogging force. Fringing flux was evaluated through the application of a magnetic boundary condition. The infinity boundary was used to include the zero electromagnetic potential in the surface boundary. A complete simulation was run for each step of the translator's motion, which was considered as sinusoidal. The simplification was further corrected using the real engine speed curve. The EMF was derived from the flux linkage difference in the coils at every consecutive translator position. Force was calculated in the translator and stator using a virtual work method. Optimization was performed using a subproblem strategy. It was concluded that the generator can be used to supply electric power as a stand-alone system, emergency power supply, or as part of an integrated system. 11 refs., 2 tabs., 10 figs.

  11. ADAPTIVE FLUX OBSERVER FOR PERMANENT MAGNET SYNCHRONOUS MOTORS

    Directory of Open Access Journals (Sweden)

    A. A. Bobtsov

    2015-01-01

    Full Text Available The paper deals with the observer design problem for a flux in permanent magnet synchronous motors. It is assumed that some electrical parameters such as resistance and inductance are known numbers. But the flux, the angle and the speed of the rotor are unmeasurable. The new robust approach to design an adaptive flux observer is proposed that guarantees globally boundedness of all signals and, moreover, exponential convergence to zero of observer error between the true flux value and an estimate obtained from the adaptive observer. The problem of an adaptive flux observer design has been solved with using the trigonometrical properties and linear filtering which ensures cancellation of unknown terms arisen after mathematical calculations. The key idea is the new parameterization of the dynamical model containing unknown parameters and depending on measurable current and voltage in the motor. By applying the Pythagorean trigonometric identity the linear equation has found that does not contain any functions depending on angle or angular velocity of the rotor. Using dynamical first-order filters the standard regression model is obtained that consists of unknown constant parameters and measurable functions of time. Then the gradient-like estimator is designed to reconstruct unknown parameters, and it guarantees boundedness of all signals in the system. The proposition is proved that if the regressor satisfies the persistent excitation condition, meaning the “frequency-rich” signal, then all errors in observer exponentially converges to zero. It is shown that observer error for the flux explicitly depends on estimator errors. Exponential convergence of parameter estimation errors to zero yields exponential convergence of the flux observer error to zero. The numerical example is considered.

  12. Design and Demonstration of a Test-Rig for Static Performance-Studies of Permanent Magnet Couplings

    DEFF Research Database (Denmark)

    Högberg, Stig; Jensen, Bogi Bech; Bendixen, Flemming Buus

    2013-01-01

    The design and construction of an easy-to-use test-rig for permanent magnet couplings is presented. Static torque of permanent magnet couplings as a function of angular displacement is measured of permanent magnet couplings through an semi-automated test system. The test-rig is capable of measuring...

  13. Magnetic Field Equivalent Current Analysis-Based Radial Force Control for Bearingless Permanent Magnet Synchronous Motors

    Directory of Open Access Journals (Sweden)

    Huangqiu Zhu

    2015-05-01

    Full Text Available Bearingless permanent magnet synchronous motors (BPMSMs, with all advantages of permanent magnet motors (PMSMs and magnetic bearings, have become an important research direction in the bearingless motor field. To realize a stable suspension for the BPMSM, accurate decoupling control between the electromagnetic torque and radial suspension force is indispensable. In this paper, a concise and reliable analysis method based on a magnetic field equivalent current is presented. By this analysis method, the operation principle is analyzed theoretically, and the necessary conditions to produce a stable radial suspension force are confirmed. In addition, mathematical models of the torque and radial suspension force are established which is verified by the finite element analysis (FEA software ANSYS. Finally, an experimental prototype of a 2-4 poles surface-mounted BPMSM is tested with the customized control strategy. The simulation and experimental results have shown that the motor has good rotation and suspension performance, and validated the accuracy of the proposed analysis method and the feasibility of the control strategy.

  14. Permanent-magnet helical undulator for a millimeter-wave free electron laser

    International Nuclear Information System (INIS)

    Lee, Jongmin; Jeong, Young-Uk; Lee, Byung-Cheol; Kim, Sun-Kook; Cho, Sung-Oh

    1995-01-01

    Permanent-magnet helical undulator for a millimeter-wave free-electron laser was designed and constructed. The configuration of the undulator is based on bifilar-type permanent-magnet helical undulator and Halbach-type planar undulator. This new configuration shows enhanced magnetic field and low field error. Period, total length and peak magnetic-field amplitude of the undulator is 36 mm, 900 mm and 1.44 kG, respectively. Adiabatic tapering of the magnetic field in end sides of the undulator was achieved using stepped soft-iron tubes. (author)

  15. Levitation force on a permanent magnet over a superconducting plane: Modified critical-state model

    International Nuclear Information System (INIS)

    Yang, Z.J.

    1997-01-01

    The authors consider a model system of a permanent magnet above a semi-infinite superconductor. They introduce a modified critical-state model, and carry out derivations of the levitation force acting on the magnet. A key feature of the modification allows the current density to be less than the critical value. The theoretical results show an exponential relationship between the force and the distance. Analytical expressions are developed for permanent magnets in the form of a point dipole, a tip of a magnetic force microscope, and a cylindrical magnet. In the latter case, the exponential relationship has been observed in numerous experiments but without previous interpretation

  16. High resolution NMR imaging using a high field yokeless permanent magnet.

    Science.gov (United States)

    Kose, Katsumi; Haishi, Tomoyuki

    2011-01-01

    We measured the homogeneity and stability of the magnetic field of a high field (about 1.04 tesla) yokeless permanent magnet with 40-mm gap for high resolution nuclear magnetic resonance (NMR) imaging. Homogeneity was evaluated using a 3-dimensional (3D) lattice phantom and 3D spin-echo imaging sequences. In the central sphere (20-mm diameter), peak-to-peak magnetic field inhomogeneity was about 60 ppm, and the root-mean-square was 8 ppm. We measured room temperature, magnet temperature, and NMR frequency of the magnet simultaneously every minute for about 68 hours with and without the thermal insulator of the magnet. A simple mathematical model described the magnet's thermal property. Based on magnet performance, we performed high resolution (up to [20 µm](2)) imaging with internal NMR lock sequences of several biological samples. Our results demonstrated the usefulness of the high field small yokeless permanent magnet for high resolution NMR imaging.

  17. High resolution NMR imaging using a high field yokeless permanent magnet

    International Nuclear Information System (INIS)

    Kose, Katsumi; Haishi, Tomoyuki

    2011-01-01

    We measured the homogeneity and stability of the magnetic field of a high field (about 1.04 tesla) yokeless permanent magnet with 40-mm gap for high resolution nuclear magnetic resonance (NMR) imaging. Homogeneity was evaluated using a 3-dimensional (3D) lattice phantom and 3D spin-echo imaging sequences. In the central sphere (20-mm diameter), peak-to-peak magnetic field inhomogeneity was about 60 ppm, and the root-mean-square was 8 ppm. We measured room temperature, magnet temperature, and NMR frequency of the magnet simultaneously every minute for about 68 hours with and without the thermal insulator of the magnet. A simple mathematical model described the magnet's thermal property. Based on magnet performance, we performed high resolution (up to [20 μm] 2 ) imaging with internal NMR lock sequences of several biological samples. Our results demonstrated the usefulness of the high field small yokeless permanent magnet for high resolution NMR imaging. (author)

  18. Topology optimization of the permanent magnet type MRI considering the magnetic field homogeneity

    International Nuclear Information System (INIS)

    Lee, Junghoon; Yoo, Jeonghoon

    2010-01-01

    This study is to suggest a concept design of the permanent magnet (PM) type magnetic resonance imaging (MRI) device based on the topology optimization method. The pulse currents in the gradient coils in the MRI device will introduce the effect of eddy currents in ferromagnetic material and it may worsen the quality of imaging. To equalize the magnetic flux in the PM type MRI device for good imaging, the eddy current effect in the ferromagnetic material must be reduced. This study attempts to use the topology optimization scheme for equalizing the magnetic flux in the measuring domain of the PM type MRI device using that the magnetic flux can be calculated directly by a commercial finite element analysis package. The density method is adopted for topology optimization and the sensitivity of the objective function is computed according to the density change of each finite element in the design domain. As a result, optimal shapes of the pole of the PM type MRI device can be obtained. The commercial package, ANSYS, is used for analyzing the magnetic field problem and obtaining the resultant magnetic flux.

  19. A Novel Integral 5-DOFs Hybrid Magnetic Bearing with One Permanent Magnet Ring Used for Turboexpander

    Directory of Open Access Journals (Sweden)

    Bangcheng Han

    2014-01-01

    Full Text Available We propose a novel combined five-degrees-of-freedom (5-DOFs hybrid magnetic bearing (HMB with only one permanent magnet ring (PMR used for turboexpanders. It has two radial magnetic bearing (RMB units; each has four poles and one thrust magnetic bearing (TMB to control 5-DOFs. Based on one PMR, the bias flux of the two radial magnetic bearing units and the one thrust magnetic bearing unit is constructed. As a result, ultra-high-speed, lower power loss, small size, and low cost can be achieved. Furthermore, the equivalent magnetic circuit method and 3D finite element method (FEM are used to model and analyze the combined 5-DOFs HMB. The force-current, force-position, torque-coil currents, the torque-angle position, and the stiffness models of the combined 5-DOFs HMB are given. Moreover, its coupling problems between the RMB units and the AMB unit are also proposed in this paper. An example is given to clarify the mathematical models and the coupling problems, and the linearized models are proposed for the follow-up controller design.

  20. Tuning Ce distribution for high performanced Nd-Ce-Fe-B sintered magnets

    Energy Technology Data Exchange (ETDEWEB)

    Fan, Xiaodong [School of Materials Science and Engineering, Xi’an University of Technology, Xi’an 710048 (China); Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Material Technology and Engineering, Chinese Academy of Science, Ningbo 315201 (China); Guo, Shuai; Chen, Kan; Chen, Renjie; Lee, Don [Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Material Technology and Engineering, Chinese Academy of Science, Ningbo 315201 (China); You, Caiyin, E-mail: caiyinyou@xaut.edu.cn [School of Materials Science and Engineering, Xi’an University of Technology, Xi’an 710048 (China); Yan, Aru, E-mail: aruyan@nimte.ac.cn [Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Material Technology and Engineering, Chinese Academy of Science, Ningbo 315201 (China)

    2016-12-01

    A dual-alloy method was applied to tune the distribution of Ce for enhancing the performance of Nd-Ce-Fe-B sintered magnets with a nominal composition of (Nd{sub 0.75}Ce{sub 0.25}){sub 30.5}Fe{sub bal}Al{sub 0.1}Cu{sub 0.1}B. In comparison to the single alloy of (Nd{sub 0.75}Ce{sub 0.25}){sub 30.5}Fe{sub bal}Al{sub 0.1}Cu{sub 0.1}B, the coercivity was enhanced from 10.3 kOe to 12.1 kOe and the remanence was increased from 13.1 kG to 13.3 kG for the magnets with a dual-alloy method. In addition, the remanence temperature coefficient α and coercivity temperature coefficient β were also slightly improved for the magnet with the dual alloys. The results of microstructure characterizations show the uniform distribution of Ce for the magnet with a single alloy, and the coexistence of the Ce-rich and Ce-lean regions for the magnet with the dual alloys. In combinations with the nucleation of reversal domains and magnetic recoil curves, the property enhancement of magnets with a dual-alloy method was well explained. - Highlights: • Improved magnetic properties were obtained in dual-alloy magnet. • This is due to the tuning of Ce distribution and the change in microstructure. • The magnetic hardening effect can be observed in dual-alloy magnet.