Study of Magnetic Properties on the Corrosion Behavior and Influence of Temperature in Permanent Magnet (Nd-Fe-B) Used in PMSM

OpenAIRE

N. Yogal; C. Lehrmann

2014-01-01

The use of permanent magnets (PM) is increasing in permanent magnet synchronous machines (PMSM) to fulfill the requirements of high efficiency machines in modern industry. PMSM are widely used in industrial applications, wind power plants and the automotive industry. Since PMSM are used in different environmental conditions, the long-term effect of NdFeB-based magnets at high temperatures and their corrosion behavior have to be studied due to the irreversible loss of magn...

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).

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.)

Maglev performance of a double-layer bulk high temperature superconductor above a permanent magnet guideway

International Nuclear Information System (INIS)

Deng, Z; Wang, J; Zheng, J; Lin, Q; Zhang, Y; Wang, S

2009-01-01

In order to improve the performance of the present high temperature superconducting (HTS) maglev vehicle system, the maglev performance of single- and double-layer bulk high temperature superconductors (HTSC) was investigated above a permanent magnet guideway (PMG). It is found that the maglev performance of a double-layer bulk HTSC is not a simple addition of each layer's levitation and guidance force. Moreover, the applied magnetic field at the position of the upper layer bulk HTSC is not completely shielded by the lower layer bulk HTSC either. 53.5% of the levitation force and 27.5% of the guidance force of the upper layer bulk HTSC are excited in the double-layer bulk HTSC arrangement in the applied field-cooling condition and working gap, bringing a corresponding improvement of 16.9% and 8.8% to the conventional single-layer bulk HTSC. The present research implies that the cost performance of upper layer bulk HTSC is a little low for the whole HTS maglev system.

Maglev performance of a double-layer bulk high temperature superconductor above a permanent magnet guideway

Energy Technology Data Exchange (ETDEWEB)

Deng, Z; Wang, J; Zheng, J; Lin, Q; Zhang, Y; Wang, S [Applied Superconductivity Laboratory, Southwest Jiaotong University, Chengdu, 610031 (China)], E-mail: asclab@asclab.cn

2009-05-15

In order to improve the performance of the present high temperature superconducting (HTS) maglev vehicle system, the maglev performance of single- and double-layer bulk high temperature superconductors (HTSC) was investigated above a permanent magnet guideway (PMG). It is found that the maglev performance of a double-layer bulk HTSC is not a simple addition of each layer's levitation and guidance force. Moreover, the applied magnetic field at the position of the upper layer bulk HTSC is not completely shielded by the lower layer bulk HTSC either. 53.5% of the levitation force and 27.5% of the guidance force of the upper layer bulk HTSC are excited in the double-layer bulk HTSC arrangement in the applied field-cooling condition and working gap, bringing a corresponding improvement of 16.9% and 8.8% to the conventional single-layer bulk HTSC. The present research implies that the cost performance of upper layer bulk HTSC is a little low for the whole HTS maglev system.

Novel High Temperature Magnetic Bearings for Space Vehicle Systems, Phase II

Data.gov (United States)

National Aeronautics and Space Administration — Previous high temperature magnetic bearings employed electromagnets only. The work proposed in this SBIR program seeks to utilize High Temperature Permanent Magnets...

Novel High Temperature Magnetic Bearings for Space Vehicle Systems, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — Previous high temperature magnetic bearings employed only electromagnets. The work proposed in this SBIR program seeks to utilize High Temperature Permanent Magnets...

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.

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.

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...

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.

Experimental evaluation of permanent magnet probe flowmeter measuring high temperature liquid sodium flow in the ITSL

Energy Technology Data Exchange (ETDEWEB)

Jeong, Uiju; Kim, Yun Ho [Nuclear engineering Department, Hanyang University, 17 Haengdang-dong, Seongdong-gu, Seoul 133-791 (Korea, Republic of); Kim, Jong-Man; Kim, Tae-Joon [Korea Atomic Energy Research Institute, 1045 Daedeok-daero, Yuseong-gu, Daejeon 305-353 (Korea, Republic of); Kim, Sung Joong, E-mail: sungjkim@mit.edu [Nuclear engineering Department, Hanyang University, 17 Haengdang-dong, Seongdong-gu, Seoul 133-791 (Korea, Republic of)

2013-12-15

Highlights: • An Instrument Test Sodium Loop (ITSL) has been built and tested in various conditions at KAERI. • Free fall of liquid sodium was conducted experimentally and numerically. • A Permanent Magnet Probe Flowmeter (PMPF) was experimented in the ITSL. • Excellent linearity of the PMPF was achieved under high temperature condition. - Abstract: The Instrument Test Sodium Loop (ITSL) installed at Korea Atomic Energy Research Institute (KAERI) is a medium-size experimental facility dedicated to obtaining relevant experimental data of liquid sodium flow characteristics under various thermal hydraulic conditions and sodium purification. The ITSL has been utilized to perform thermal flow measurement of the liquid sodium and to calibrate a Permanent Magnet Probe Flowmeter (PMPF). The primary objective of this study is to obtain liquid sodium flow rate given a wide temperature range using the PMPF. Non-stationary method was adopted for the calibration of the probe given the liquid sodium temperature range of 150–415 °C. A relationship between the measured voltage signal and flow rate was obtained successfully. It is observed that the calibration experiments result in excellent linear relationships between measured voltage and volumetric flow rate at various temperature conditions. Also a computational analysis using FlowMaster, is employed to facilitate the calibration process by predicting the liquid sodium flow rate. Finally the effect of the fluid temperature on thermal flow measurements is discussed in light of the obtained experimental data.

Measurement of NdFeB permanent magnets demagnetization induced by high energy electron radiation

Energy Technology Data Exchange (ETDEWEB)

Temnykh, Alexander B. [Wilson Lab, Cornell University, LEPP, Ithaca, NY 14850 (United States)], E-mail: abt6@cornell.edu

2008-03-11

Demagnetization of NdFeB permanent magnets has been measured as function of radiation dose induced by high energy electrons. The magnet samples were of different intrinsic coercive forces, {approx_equal}12 and {approx_equal}20KOe, dimensions and direction of magnetization. 5 GeV electron beam from 12 GeV Cornell Synchrotron was used as a radiation source. A calorimetric technique was employed for radiation dose measurement. Results indicated that depending on the sample intrinsic coercive force, shape and direction of magnetization the radiation dose causing 1% of demagnetization of the sample varies from 0.0765{+-}0.005Mrad to 11.3{+-}3.0Mrad, i.e., by more than a factor of 100. Experimental data analysis revealed that demagnetization of the given sample induced by radiation is strongly correlated with the sample demagnetizing temperature. This correlation was approximated by an exponential function with two parameters obtained from the data fitting. The function can be used to predict the critical radiation dose for permanent magnet assemblies like undulator magnets based on its demagnetizing temperature. The latter (demagnetization temperature) can be determined at the design stage from 3-D magnetic modeling and permanent magnet material properties.

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

A two-pole Halbach permanent magnet guideway for high temperature superconducting Maglev vehicle

International Nuclear Information System (INIS)

Jing, H.; Wang, J.; Wang, S.; Wang, L.; Liu, L.; Zheng, J.; Deng, Z.; Ma, G.; Zhang, Y.; Li, J.

2007-01-01

In order to improve the levitation performance of the high temperature superconducting (HTS) magnetic levitation (Maglev) vehicle, a two-pole Halbach array's permanent magnet guideway (PMG) is proposed, which is called as Halbach PMG. The finite element method (FEM) calculations indicate that Halbach PMG has a wider high-field region than the present PMG of equal PM's transverse section. The levitation force of bulk HTSCs with the present PMG and Halbach PMG are measured. The results show that at different levitation gaps, the force ratios based on the Halbach PMG are about 2.3 times larger than that on the present PMG, which greatly increases the load capability of the system. Therefore, both the numerical analysis and experimental results have confirmed that the Halbach PMG will further enhance the performance of the vehicle and it is possible to decrease the total numbers of onboard HTSCs, reducing overall costs. So based on the Halbach PMG, we further study the width ratios between HTSCs and PMG for making the better use of the onboard HTSCs. Some preliminary results are given. These results are important for further HTS Maglev vehicle system designs using Halbach PMG

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.

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)

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.

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.

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.

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.

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.

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)

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

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)

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

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.)

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.

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

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.

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.

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.

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...

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.

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

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

Cerium: an unlikely replacement of dysprosium in high performance Nd-Fe-B permanent magnets.

Science.gov (United States)

Pathak, Arjun K; Khan, Mahmud; Gschneidner, Karl A; McCallum, Ralph W; Zhou, Lin; Sun, Kewei; Dennis, Kevin W; Zhou, Chen; Pinkerton, Frederick E; Kramer, Matthew J; Pecharsky, Vitalij K

2015-04-24

Replacement of Dy and substitution of Nd in NdFeB-based permanent magnets by Ce, the most abundant and lowest cost rare earth element, is important because Dy and Nd are costly and critical rare earth elements. The Ce, Co co-doped alloys have excellent high-temperature magnetic properties with an intrinsic coercivity being the highest known for T ≥ 453 K. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Equivalent Coil Model for Computing Levitation Forces Between Permanent Magnets and High Temperatures Superconductors

International Nuclear Information System (INIS)

Cavia Santos, S.; Garcia-Tabares, L.

1998-05-01

A new simple theory has been developed for the study of levitation forces between a permanent magnet and a HTc superconductor. This theory is based on the assumption that both, the magnet and the superconductor, can be modelled by an equivalent coil placed on their surface. While the current flowing through the permanent magnet is constant, the equivalent current through the superconductor can be iether corresponding to screen the overall flux or a constant current corresponding to critical current density when the superconductor is saturated. A test facility has been designed and built for measuring levitation forces at variable approaching speeds. Comparison between theoretical and experimental measurements are presented in the report as well as a general description of the test facility. (Author)

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.

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.

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.

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

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....

Comparison of properties of Nd-Fe-B and Sm-Co permanent magnets

International Nuclear Information System (INIS)

Ervens, W.

1985-01-01

In this paper permanent magnet materials on the basis of RECo and NdFeB are compared in terms of manufacturing processes, magnetic values at ambient and elevated temperatures, maximum operating temperatures and magnetization behaviour. At the present stage of development NdFeB-magnets are superior to the high coercivity RECo-magnets in their B/sub r/ - and (BH)/sub ma//sup -/ values at room temperature but are inferior to them at temperatures higher than 120 0 C

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)

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

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.

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)

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.

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.

Temperature mapping using proton phase shift on a 0.3 T permanent magnet open MRI system

International Nuclear Information System (INIS)

Komura, Kazumi; Takahashi, Tetsuhiko; Dohi, Michiko; Harada, Junta

2000-01-01

Temperature mapping using proton phase shift (PPS) was evaluated for ex vivo objects. The evaluation was done on a 0.3 T permanent magnet open magnetic resonance imaging (MRI) machine, like those widely used for clinical diagnosis. Temperature maps were acquired using a gradient echo sequence (TR/TE =80/30 ms, flip angle =60 degrees, field of view =200 x 200 mm, slice thickness =8 mm, matrix size =128 x 128, data acquisition number =1, and imaging time =10.2 s). Specific first order data correction was performed to eliminate calculated temperature fluctuation due to magnetic field instability. A ham, 10 cm in diameter, was heated with a Nd: YAG laser with a wavelength of 1064 nm. The laser fiber was inserted into the ham to a depth of 3 cm. The laser power was 5, 8, or 10 W. Magnetic resonance images were taken continually during and after irradiation. Temperature maps were taken every 15 s. The maps taken during laser ablation showed color changes for the heated areas. Temperatures measured by the MRI and thermocouple had a linear relationship of r 2 =0.80. The inter-image standard deviation of the temperature maps of a non-heated object was 2.07 degrees for a 4.68 x 4.68 x 8 mm volume. This value is negligible for a monitored laser heating process since temperature rise is typically larger than 30 degrees. These results show that temperature mapping based on PPS is feasible for a 0.3 T permanent magnet open MRI system. (author)

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

Generation of strong inhomogeneous stray fields by high-anisotropy permanent magnets

Energy Technology Data Exchange (ETDEWEB)

Samofalov, V.N. [National Technical University Kharkov Polytechnical Institute, 21 Frunze St., 61002 Kharkov (Ukraine)]. E-mail: samofalov@kpi.kharkov.ua; Ravlik, A.G. [National Technical University Kharkov Polytechnical Institute, 21 Frunze St., 61002 Kharkov (Ukraine); Belozorov, D.P. [National Scientific Center Kharkov Institute of Physics and Techonology, NAS of Ukraine, 1 Akademicheskaja St., 61108 Kharkov (Ukraine); Avramenko, B.A. [National Technical University Kharkov Polytechnical Institute, 21 Frunze St., 61002 Kharkov (Ukraine)

2004-10-01

Magnetic stray fields for systems of permanent magnets with high magnetic anisotropy are calculated and measured. It is shown that intensity of these fields exceeds value of an induction of a material of magnets in some time. Besides, these fields are characterized by high gradients, and size H-bar H can reach values up to10{sup 10}-10{sup 11}Oe{sup 2}/cm. Estimations of extremely achievable fields and their gradients are made.

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.

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.

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.

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.

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.

A Torque Error Compensation Algorithm for Surface Mounted Permanent Magnet Synchronous Machines with Respect to Magnet Temperature Variations

Directory of Open Access Journals (Sweden)

Chang-Seok Park

2017-09-01

Full Text Available This paper presents a torque error compensation algorithm for a surface mounted permanent magnet synchronous machine (SPMSM through real time permanent magnet (PM flux linkage estimation at various temperature conditions from medium to rated speed. As known, the PM flux linkage in SPMSMs varies with the thermal conditions. Since a maximum torque per ampere look up table, a control method used for copper loss minimization, is developed based on estimated PM flux linkage, variation of PM flux linkage results in undesired torque development of SPMSM drives. In this paper, PM flux linkage is estimated through a stator flux linkage observer and the torque error is compensated in real time using the estimated PM flux linkage. In this paper, the proposed torque error compensation algorithm is verified in simulation and experiment.

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

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

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.

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

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)

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

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)

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.

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.

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

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.

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

Anisotropy and Microstructure of High Coercivity Rare Earth Iron Permanent Magnets, List of Papers Published

Science.gov (United States)

1989-01-01

hardly influences both the pared by three different production technologies, absolute value of HA and its temperature dependence. The permanent magnets...ing reverse domains [2]. pared from 99.5% pure cast material supplied by The application of these magnets has been Rare Earth Products. The...the c/ re 3b Fig.. E ncrographs showingthe celular precipitation structure of precipitation hardened SmCo 2:17 magnets (a). In low coercivity magnets

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

Development and operation of a Pr_{2}Fe_{14}B based cryogenic permanent magnet undulator for a high spatial resolution x-ray beam line

Directory of Open Access Journals (Sweden)

C. Benabderrahmane

2017-03-01

Full Text Available Short period, high field undulators are used to produce hard x-rays on synchrotron radiation based storage ring facilities of intermediate energy and enable short wavelength free electron laser. Cryogenic permanent magnet undulators take benefit from improved magnetic properties of RE_{2}Fe_{14}B (Rare Earth based magnets at low temperatures for achieving short period, high magnetic field and high coercivity. Using Pr_{2}Fe_{14}B instead of Nd_{2}Fe_{14}B, which is generally employed for undulators, avoids the limitation caused by the spin reorientation transition phenomenon, and simplifies the cooling system by allowing the working temperature of the undulator to be directly at the liquid nitrogen one (77 K. We describe here the development of a full scale (2 m, 18 mm period Pr_{2}Fe_{14}B cryogenic permanent magnet undulator (U18. The design, construction and optimization, as well as magnetic measurements and shimming at low temperature are presented. The commissioning and operation of the undulator with the electron beam and spectrum measurement using the Nanoscopmium beamline at SOLEIL are also reported.

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.

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

Research on Strategies and Methods Suppressing Permanent Magnet Demagnetization in Permanent Magnet Synchronous Motors Based on a Multi-Physical Field and Rotor Multi-Topology Structure

Directory of Open Access Journals (Sweden)

Lin Li

2017-12-01

Full Text Available In this paper, a permanent magnet synchronous motor (PMSM with sleeves on the rotor outer surface is investigated. The purpose of sleeves is to fix the permanent magnets and protect them from being destroyed by the large centrifugal force. However, the sleeve material characteristics have a great influence on the PMSM, and therewith, most of the rotor eddy-current losses are generated in the rotor sleeve, which could increase the device temperature and even cause thermal demagnetization of the magnets. Thus, a sleeve scheme design with low eddy-current losses is necessary, and a method suppressing the local temperature peak of permanent magnets is presented. The 3-D electromagnetic finite element model of a 12.5 kW, 2000 r/min PMSM with a segmented sleeve is established, and the electromagnetic field is calculated by using the finite element method. The results show the effectiveness of the presented method in reducing the eddy current losses in the rotor. Using the thermal method, it can be found that the maximum temperature position and zone of permanent magnet will change. Thus, some strategies are comparatively analyzed in order to obtain the change rule of the position and zone. The obtained conclusions may provide a useful reference for the design and research of PMSMs.

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.

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.

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)

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.)

Performance of high power S-band klystrons focused with permanent magnet

International Nuclear Information System (INIS)

Fukuda, S.; Shidara, T.; Saito, Y.; Hanaki, H.; Nakao, K.; Homma, H.; Anami, S.; Tanaka, J.

1987-02-01

Performance of high power S-band klystrons focused with permanent magnet is presented. The axial magnetic field distribution and the transverse magnetic field play an important role in the tube performance. Effects of the reversal field in the collector and the cathode-anode region are discussed precisely. It is also shown that the tube efficiency is strongly affected with the residual transverse magnetic field. The allowable transverse field is less than 0.3 % of the longitudinal field in the entire rf interaction region of the klystron. (author)

Performance of high power S-band klystrons focused with permanent magnet

Science.gov (United States)

Fukuda, S.; Shidara, T.; Saito, Y.; Hanaki, H.; Nakao, K.; Homma, H.; Anami, S.; Tanaka, J.

1987-02-01

Performance of high power S-band klystrons focused with permanent magnet is presented. The axial magnetic field distribution and the transverse magnetic field play an important role in the tube performance. Effects of the reversal field in the collector and the cathode-anode region are discussed precisely. It is also shown that the tube efficiency is strongly affected with the residual transverse magnetic field. The allowable transverse field is less than 0.3 percent of the longitudinal field in the entire RF interaction region of the klystron.

Low-temperature phase MnBi compound: A potential candidate for rare-earth free permanent magnets

International Nuclear Information System (INIS)

Ly, V.; Wu, X.; Smillie, L.; Shoji, T.; Kato, A.; Manabe, A.; Suzuki, K.

2014-01-01

Highlights: • The spin reorientation temperature of MnBi is suppressed by nanoscale grain refinement. • Hardness parameter of MnBi reaches as large as 2.8 at 580 K. • MnBi has a great potential as a hard phase in rare-earth free nanocomposite magnets. • Improving the surface passivity is a remaining task for MnBi-based permanent magnets. - Abstract: The low-temperature phase (LTP) MnBi is one of the few rare-earth free compounds that exhibit a large magnetocrystalline anisotropy energy in the order of 10 6 J/m 3 . A large coercive field (μ 0 H cj ) above 1 T can be obtained readily by reducing the crystallite size (D) through mechanical grinding (MG). The room-temperature H cj values follow a phenomenological expression μ 0 H cj = μ 0 H a (δ/D) n where the anisotropy field (μ 0 H a ) is ∼4 T, the Bloch wall width (δ) is 7 nm and the exponent (n) is about 0.7 in our study. The grain refinement upon MG is accompanied by suppression of the spin reorientation transition temperature (T SR ) from 110 K to below 50 K. The coercive field starts to exhibit positive temperature dependence approximately 50 K above T SR and the room-temperature magnetic hardening induced by MG could partially be brought about by the lowered onset of this positive temperature dependence. The suppression of T SR by MG is likely to be induced by the surface anisotropy with which the 2nd order crystal field term is enhanced. One of the shortcomings of LTP-MnBi is its poor phase stability under the ambient atmosphere. The spontaneous magnetization decreases considerably after room-temperature aging for 1 week. This is due to oxidation of Mn which leads to decomposition of the MnBi phase. Hence, the surface passivity needs to be established before this material is considered for a permanent magnet in practical uses. Another shortcoming is the limited spontaneous magnetization. The theoretical upper limit of the maximum energy product in LTP-MnBi remains only a quarter of that in Nd 2

Low-temperature phase MnBi compound: A potential candidate for rare-earth free permanent magnets

Energy Technology Data Exchange (ETDEWEB)

Ly, V.; Wu, X.; Smillie, L. [Department of Materials Engineering, Monash University, Clayton, VIC 3800 (Australia); Shoji, T.; Kato, A.; Manabe, A. [Toyota Motor Corporation, Mishuku, Susono, Shizuoka 410-1193 (Japan); Suzuki, K., E-mail: kiyonori.suzuki@monash.edu [Department of Materials Engineering, Monash University, Clayton, VIC 3800 (Australia)

2014-12-05

Highlights: • The spin reorientation temperature of MnBi is suppressed by nanoscale grain refinement. • Hardness parameter of MnBi reaches as large as 2.8 at 580 K. • MnBi has a great potential as a hard phase in rare-earth free nanocomposite magnets. • Improving the surface passivity is a remaining task for MnBi-based permanent magnets. - Abstract: The low-temperature phase (LTP) MnBi is one of the few rare-earth free compounds that exhibit a large magnetocrystalline anisotropy energy in the order of 10{sup 6} J/m{sup 3}. A large coercive field (μ{sub 0}H{sub cj}) above 1 T can be obtained readily by reducing the crystallite size (D) through mechanical grinding (MG). The room-temperature H{sub cj} values follow a phenomenological expression μ{sub 0}H{sub cj} = μ{sub 0}H{sub a}(δ/D){sup n} where the anisotropy field (μ{sub 0}H{sub a}) is ∼4 T, the Bloch wall width (δ) is 7 nm and the exponent (n) is about 0.7 in our study. The grain refinement upon MG is accompanied by suppression of the spin reorientation transition temperature (T{sub SR}) from 110 K to below 50 K. The coercive field starts to exhibit positive temperature dependence approximately 50 K above T{sub SR} and the room-temperature magnetic hardening induced by MG could partially be brought about by the lowered onset of this positive temperature dependence. The suppression of T{sub SR} by MG is likely to be induced by the surface anisotropy with which the 2nd order crystal field term is enhanced. One of the shortcomings of LTP-MnBi is its poor phase stability under the ambient atmosphere. The spontaneous magnetization decreases considerably after room-temperature aging for 1 week. This is due to oxidation of Mn which leads to decomposition of the MnBi phase. Hence, the surface passivity needs to be established before this material is considered for a permanent magnet in practical uses. Another shortcoming is the limited spontaneous magnetization. The theoretical upper limit of the maximum

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....

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.

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.

Using permanent magnets to boost the dipole field for the High-Energy LHC

CERN Document Server

Zimmermann, Frank

2012-01-01

The High-Energy LHC (HE-LHC) will be a new accelerator in the LHC tunnel based on novel dipole magnets, with a field up to 20 T, which are proposed to be realized by a hybrid-coil design, comprising blocks made from Nb- Ti, Nb$_{3}$Sn and HTS, respectively. Without the HTS the field would be only 15 T. In this note we propose and study the possibility of replacing the inner HTS layer by (weaker) permanent magnets that might contribute a field of 1-2 T, so that the final field would reach 16-17 T. Advantages would be the lower price of permanent magnets compared with HTS magnets and their availability in principle.

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.

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.

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

Superconducting permanent magnets for high-temperature operation

Czech Academy of Sciences Publication Activity Database

Jirsa, Miloš; Muralidhar, M.

2004-01-01

Roč. 54, Suppl. D (2004), D441-D444 ISSN 0011-4626. [Czech and Slovak Conference on Magnetism. Košice, 12.07.2004-15.07.2004] Institutional research plan: CEZ:AV0Z1010914 Keywords : superconducting magnets * ternary LRE-123 compounds * mesoscopic defects Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.292, year: 2004

Dynamic response characteristics of high temperature superconducting maglev systems: Comparison between Halbach-type and normal permanent magnet guideways

Science.gov (United States)

Wang, B.; Zheng, J.; Che, T.; Zheng, B. T.; Si, S. S.; Deng, Z. G.

2015-12-01

The permanent magnet guideway (PMG) is very important for the performance of the high temperature superconducting (HTS) system in terms of electromagnetic force and operational stability. The dynamic response characteristics of a HTS maglev model levitating on two types of PMG, which are the normal PMG with iron flux concentration and Halbach-type PMG, were investigated by experiments. The dynamic signals for different field-cooling heights (FCHs) and loading/unloading processes were acquired and analyzed by a vibration analyzer and laser displacement sensors. The resonant frequency, stiffness and levitation height of the model were discussed. It was found that the maglev model on the Halbach-type PMG has higher resonant frequency and higher vertical stiffness compared with the normal PMG. However, the low lateral stiffness of the model on the Halbach-type PMG indicates poor lateral stability. Besides, the Halbach-type PMG has better loading capacity than the normal PMG. These results are helpful to design a suitable PMG for the HTS system in practical applications.

Operation and design selection of high temperature superconducting magnetic bearings

International Nuclear Information System (INIS)

Werfel, F N; Floegel-Delor, U; Riedel, T; Rothfeld, R; Wippich, D; Goebel, B

2004-01-01

Axial and radial high temperature superconducting (HTS) magnetic bearings are evaluated by their parameters. Journal bearings possess advantages over thrust bearings. High magnetic gradients in a multi-pole permanent magnet (PM) configuration, the surrounding melt textured YBCO stator and adequate designs are the key features for increasing the overall bearing stiffness. The gap distance between rotor and stator determines the specific forces and has a strong impact on the PM rotor design. We report on the designing, building and measuring of a 200 mm prototype 100 kg HTS bearing with an encapsulated and thermally insulated melt textured YBCO ring stator. The encapsulation requires a magnetically large-gap (4-5 mm) operation but reduces the cryogenic effort substantially. The bearing requires 3 l of LN 2 for cooling down, and about 0.2 l LN 2 h -1 under operation. This is a dramatic improvement of the efficiency and in the practical usage of HTS magnetic bearings

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.

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.

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.

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.

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.

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.

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....

Analysis and Design Considerations of a High-Power Density, Dual Air Gap, Axial-Field Brushless, Permanent Magnet Motor.

Science.gov (United States)

Cho, Chahee Peter

1995-01-01

Until recently, brush dc motors have been the dominant drive system because they provide easily controlled motor speed over a wide range, rapid acceleration and deceleration, convenient control of position, and lower product cost. Despite these capabilities, the brush dc motor configuration does not satisfy the design requirements for the U.S. Navy's underwater propulsion applications. Technical advances in rare-earth permanent magnet materials, in high-power semiconductor transistor technology, and in various rotor position-sensing devices have made using brushless permanent magnet motors a viable alternative. This research investigates brushless permanent magnet motor technology, studying the merits of dual-air gap, axial -field, brushless, permanent magnet motor configuration in terms of power density, efficiency, and noise/vibration levels. Because the design objectives for underwater motor applications include high-power density, high-performance, and low-noise/vibration, the traditional, simplified equivalent circuit analysis methods to assist in meeting these goals were inadequate. This study presents the development and verification of detailed finite element analysis (FEA) models and lumped parameter circuit models that can calculate back electromotive force waveforms, inductance, cogging torque, energized torque, and eddy current power losses. It is the first thorough quantification of dual air-gap, axial -field, brushless, permanent magnet motor parameters and performance characteristics. The new methodology introduced in this research not only facilitates the design process of an axial field, brushless, permanent magnet motor but reinforces the idea that the high-power density, high-efficiency, and low-noise/vibration motor is attainable.

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

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...

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.

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.

High speed internal permanent magnet machine and method of manufacturing the same

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

2011-09-13

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 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 permanent magnets for generating a magnetic field, which interacts with the stator magnetic field to produce torque. The permanent magnets are disposed between the stacks. The rotor assembly also includes multiple bottom wedges disposed on the bottom structures of the shaft and configured to hold the multiple stacks and the multiple permanent magnets.

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

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.)

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.

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)

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.

Microstructure and Phase Analysis in Mn-Al and Zr-Co Permanent Magnets

Science.gov (United States)

Lucis, Michael J.

In America's search for energy independence, the development of rare-earth free permanent magnets is one hurdle that still stands in the way. Permanent magnet motors provide a higher efficiency than induction motors in applications such as hybrid vehicles and wind turbines. This thesis investigates the ability of two materials, Mn-Al and Zr-Co, to fill this need for a permanent magnet material whose components are readily available within the U.S. and whose supply chain is more stable than that of the rare-earth materials. This thesis focuses on the creation and optimization of these two materials to later be used as the hard phase in nanocomposites with high energy products (greater than 10 MGOe). Mn-Al is capable of forming the pure L10 structure at a composition of Mn54Al43C3. When Mn is replaced by Fe or Cu using the formula Mn48Al43C3T6 the anisotropy constant is lowered from 1.3·107 ergs/cm3 to 1.0·107 ergs/cm3 and 0.8·10 7 ergs/cm3 respectively. Previous studies have reported a loss in magnetization in Mn-Al alloys during mechanical milling. The reason for this loss in magnetization was investigated and found to be due to the formation of the equilibrium beta-Mn phase of the composition Mn3Al2 and not due to oxidation or site disorder. It was also shown that fully dense Mn-Al permanent magnets can be created at hot pressing temperatures at or above 700°C and that the epsilon-phase to tau-phase transition and consolidation can be combined into a single processing step. The addition of small amounts of Cu to the alloy, 3% atomic, can increase the compaction density allowing high densities to be achieved at lower pressing temperatures. While the structure is still under debate, alloys at the composition Zr2Co11 in the Zr-Co system have been shown to have hard magnetic properties. This thesis shows that multiple structures exist at this Zr2Co11 composition and that altering the cooling rate during solidification of the alloy affects the ratio of the phase

Low temperature superconductor and aligned high temperature superconductor magnetic dipole system and method for producing high magnetic fields

Science.gov (United States)

Gupta, Ramesh; Scanlan, Ronald; Ghosh, Arup K.; Weggel, Robert J.; Palmer, Robert; Anerella, Michael D.; Schmalzle, Jesse

2017-10-17

A dipole-magnet system and method for producing high-magnetic-fields, including an open-region located in a radially-central-region to allow particle-beam transport and other uses, low-temperature-superconducting-coils comprised of low-temperature-superconducting-wire located in radially-outward-regions to generate high magnetic-fields, high-temperature-superconducting-coils comprised of high-temperature-superconducting-tape located in radially-inward-regions to generate even higher magnetic-fields and to reduce erroneous fields, support-structures to support the coils against large Lorentz-forces, a liquid-helium-system to cool the coils, and electrical-contacts to allow electric-current into and out of the coils. The high-temperature-superconducting-tape may be comprised of bismuth-strontium-calcium-copper-oxide or rare-earth-metal, barium-copper-oxide (ReBCO) where the rare-earth-metal may be yttrium, samarium, neodymium, or gadolinium. Advantageously, alignment of the large-dimension of the rectangular-cross-section or curved-cross-section of the high-temperature-superconducting-tape with the high-magnetic-field minimizes unwanted erroneous magnetic fields. Alignment may be accomplished by proper positioning, tilting the high-temperature-superconducting-coils, forming the high-temperature-superconducting-coils into a curved-cross-section, placing nonconducting wedge-shaped-material between windings, placing nonconducting curved-and-wedge-shaped-material between windings, or by a combination of these techniques.

A Permanent-Magnet Microwave Ion Source for a Compact High-Yield Neutron Generator

International Nuclear Information System (INIS)

Waldmann, Ole; Ludewigt, Bernhard

2010-01-01

We present recent work on the development of a microwave ion source that will be used in a high-yield compact neutron generator for active interrogation applications. The sealed tube generator will be capable of producing high neutron yields, 5 · 10 11 n/s for D-T and ∼ 1 · 10 10 n/s for D-D reactions, while remaining transportable. We constructed a microwave ion source (2.45 GHz) with permanent magnets to provide the magnetic field strength of 87.5 mT necessary for satisfying the electron cyclotron resonance (ECR) condition. Microwave ion sources can produce high extracted beam currents at the low gas pressures required for sealed tube operation and at lower power levels than previously used RF-driven ion sources. A 100 mA deuterium/tritium beam will be extracted through a large slit (60 · 6 mm 2 ) to spread the beam power over a larger target area. This paper describes the design of the permanent-magnet microwave ion source and discusses the impact of the magnetic field design on the source performance. The required equivalent proton beam current density of 40 mA/cm 2 was extracted at a moderate microwave power of 400 W with an optimized magnetic field.

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.

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.

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.

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.

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

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.

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.

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.

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.

Cluster-Expansion Model for Complex Quinary Alloys: Application to Alnico Permanent Magnets

Science.gov (United States)

Nguyen, Manh Cuong; Zhou, Lin; Tang, Wei; Kramer, Matthew J.; Anderson, Iver E.; Wang, Cai-Zhuang; Ho, Kai-Ming

2017-11-01

An accurate and transferable cluster-expansion model for complex quinary alloys is developed. Lattice Monte Carlo simulation enabled by this cluster-expansion model is used to investigate temperature-dependent atomic structure of alnico alloys, which are considered as promising high-performance non-rare-earth permanent-magnet materials for high-temperature applications. The results of the Monte Carlo simulations are consistent with available experimental data and provide useful insights into phase decomposition, selection, and chemical ordering in alnico. The simulations also reveal a previously unrecognized D 03 alloy phase. This phase is very rich in Ni and exhibits very weak magnetization. Manipulating the size and location of this phase provides a possible route to improve the magnetic properties of alnico, especially coercivity.

Concept study of 20 MW high-speed permanent magnet synchronous motor for marine propulsion

NARCIS (Netherlands)

Bogomolov, M.D.

2013-01-01

High-speed permanent magnet synchronous machines are of great interest in the applications where high utilization factor and efficiency are required. Depending on application, power requirements change from kilowatts to megawatts. To investigate power limits of high-speed machines, the present

Research and development project for flywheel energy storage system using high-temperature superconducting magnetic bearing

International Nuclear Information System (INIS)

Shinagawa, Jiro; Ishikawa, Fumihiko

1996-01-01

Recent progress in the research and development of an yttrium-based oxide high-temperature superconductor has enabled the production of a large-diameter bulk with a strong flux-pinning force. A combination of this superconductor and a permanent magnet makes it feasible to fabricate a non-contact, non-controlled superconducting magnetic bearing with a very small rotational loss. Use of the superconducting magnetic bearing for a flywheel energy storage system may pave the way to the development of a new energy storage system that has great energy storage efficiency. >From relevant data measured with a miniature model of the high-temperature superconducting magnetic bearing, a conceptual design of an 8 MWh flywheel energy storage system was developed, using the new bearing which proved to be potentially capable of achieving a high energy storage efficiency of 84%. A 100 Wh-class experimental system was install that attained a high revolution rate of 17.000 rpm. (author)

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...

Study on control method of running velocity for the permanent magnet-HTSC hybrid magnetically levitated conveyance system

International Nuclear Information System (INIS)

Nishio, R.; Ikeda, M.; Sasaki, R.; Ohashi, S.

2011-01-01

The hybrid magnetically levitated carrying system is developed. Control method of running velocity of the carrier is studied. Running velocity is controlled by current of the propulsion coils. Propulsion characteristcs are improved. We have developed the magnetically levitated carrying system. In this system, pinning force of high temperature bulk super conductor (HTSC) is used for the levitation and guidance. Four HTSCs are installed on the carrier. The magnetic rail is set on the ground, and flux from the magnetic rail is pinned by HTSCs. To increase levitation force, repulsive force of the permanent magnet is used. The hybrid levitation system is composed. The permanent magnet is installed under the load stage of the carrier. Repulsive force by the permanent magnet between the load stage on the carrier and the magnetic rail on the ground is used to support the load weight. Levitation and guidance one by pinning effect of the YBaCuO HTSC in the carrier is used to levitate the carrier body. The load stage is separated from the carrier flame and can move freely for vertical direction levitation. For the propulsion system, electromagnet is installed on the surface of the magnetic rail. In this paper, control method of running velocity of the carrier is studied. Propulsion force is given as follows; Air core copper coils are installed on the magnetic rail. Interaction between current of these coils and permanent magnets on the carrier generates propulsion force. Running velocity is controlled by current of the propulsion coils. It is also changed by position of the carrier and the load weight. From the results, stability of the propulsion system is given, and propulsion characteristics are improved.

Study on control method of running velocity for the permanent magnet-HTSC hybrid magnetically levitated conveyance system

Energy Technology Data Exchange (ETDEWEB)

Nishio, R.; Ikeda, M.; Sasaki, R. [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 magnetically levitated carrying system is developed. Control method of running velocity of the carrier is studied. Running velocity is controlled by current of the propulsion coils. Propulsion characteristcs are improved. We have developed the magnetically levitated carrying system. In this system, pinning force of high temperature bulk super conductor (HTSC) is used for the levitation and guidance. Four HTSCs are installed on the carrier. The magnetic rail is set on the ground, and flux from the magnetic rail is pinned by HTSCs. To increase levitation force, repulsive force of the permanent magnet is used. The hybrid levitation system is composed. The permanent magnet is installed under the load stage of the carrier. Repulsive force by the permanent magnet between the load stage on the carrier and the magnetic rail on the ground is used to support the load weight. Levitation and guidance one by pinning effect of the YBaCuO HTSC in the carrier is used to levitate the carrier body. The load stage is separated from the carrier flame and can move freely for vertical direction levitation. For the propulsion system, electromagnet is installed on the surface of the magnetic rail. In this paper, control method of running velocity of the carrier is studied. Propulsion force is given as follows; Air core copper coils are installed on the magnetic rail. Interaction between current of these coils and permanent magnets on the carrier generates propulsion force. Running velocity is controlled by current of the propulsion coils. It is also changed by position of the carrier and the load weight. From the results, stability of the propulsion system is given, and propulsion characteristics are improved.

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

Filtering peripheral high temperature electrons in a cylindrical rf-driven plasmas by an axisymmetric radial magnetic field

Science.gov (United States)

Akahoshi, Hikaru; Takahashi, Kazunori; Ando, Akira

2018-03-01

High temperature electrons generated near a radial wall of a cylindrical source tube in a radiofrequency (rf) inductively-coupled plasma is filtered by an axisymmetric radial magnetic field formed near the source exit by locating annular permanent magnets, where the axial magnetic field strength in the radially central region is fairly uniform inside the source tube and is close to zero near the source exit. The source is operated at 3 mTorr in argon and the rf antenna is powered by a 13.56 MHz and 400 W rf generator. Measurement of electron energy probability functions shows the presence of the peripheral high temperature electrons inside the source, while the temperature of the peripheral electrons downstream of the source is observed to be reduced.

Dynamic model tracking design for low inertia, high speed permanent magnet ac motors.

Science.gov (United States)

Stewart, P; Kadirkamanathan, V

2004-01-01

Permanent magnet ac (PMAC) motors have existed in various configurations for many years. The advent of rare-earth magnets and their associated highly elevated levels of magnetic flux makes the permanent magnet motor attractive for many high performance applications from computer disk drives to all electric racing cars. The use of batteries as a prime storage element carries a cost penalty in terms of the unladen weight of the vehicle. Minimizing this cost function requires the minimum electric motor size and weight to be specified, while still retaining acceptable levels of output torque. This tradeoff can be achieved by applying a technique known as flux weakening which will be investigated in this paper. The technique allows the speed range of a PMAC motor to be greatly increased, giving a constant power range of more than 4:1. A dynamic model reference controller is presented which has advantages in ease of implementation, and is particularly suited to dynamic low inertia applications such as clutchless gear changing in high performance electric vehicles. The benefits of this approach are to maximize the torque speed envelope of the motor, particularly advantageous when considering low inertia operation. The controller is examined experimentally, confirming the predicted performance.

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...

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.

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.

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

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.

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

Experience with the procurement of ferrite and temperature compensator for permanent magnets for accelerators

International Nuclear Information System (INIS)

Fowler, W.B.; Brown, B.C.; Volk, J.

1997-07-01

The use of permanent magnets for transporting the 8 GeV proton beam from the Fermilab Booster to the new Fermilab Main Injector accelerator has been implemented and the magnets for a new 8 GeV ring to be installed in the Main Injector tunnel for increasing the luminosity of pbar/p collisions in the Tevatron are about to start being produced. Strontium oxide ferrite was selected for the magnets due to it's low cost and satisfactory magnetic properties for the 1.5 kilogauss fields required in the 2-inch gap magnets. Fermilab has received 96,000 pounds of ferrite and by working with the Vendor (HITACHI, Edmore, MI) improved uniformity of Residual Induction (Br) has reached 3905 gauss ± 0.65%. Further details are given in the paper. Overcoming the magnetic field variation when the temperature of the magnets changes is accomplished by incorporation of approximately 30% nickel steel alloy. The ferrite changes approximately -0.2% per degree C, which is compensated for by the 13% by the volume of compensator alloy incorporated in the magnet. Fourteen thousand (14,000) pounds of this material has been received and in order to obtain sufficient uniformity the authors mixed equal amounts from each batch into each magnet. Results of this process are given in the paper

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

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

Thermal Analysis on Radial Flux Permanent Magnet Generator (PMG using Finite Element Method

Directory of Open Access Journals (Sweden)

Hilman Syaeful A Syaeful A

2011-05-01

Full Text Available The main source of heat in the permanent magnet generator (PMG is the total losses which f come from winding losses, core losses and rotational losses. Total heat arising from such these losses must be properly distributed and maintained so as not to exceed the maximum allowable temperature to prevent damage to insulation on the winding and demagnetization on the permanent magnet machines. In this research, we consider thermal analysis which is occurred on the radial flux PMG by using finite element method to determine the extent to which the heat generated can be properly distributed. The simulation results show that there are no points of heat concentration or hot spot. The simulation maximum temperatures of the permanent magnet and the winding are 39.1oC and 72.5oC respectively while the experimental maximum temperature of the winding is 62oC.

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

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

A Cryogenic Magnetostrictive Actuator Using a Persistent High Temperature Superconducting Magnet. Part 1; Concept and Design

Science.gov (United States)

Horner, Garnett; Bromberg, Leslie; Teter, J. P.

2000-01-01

Cryogenic magnetostrictive materials, such as rare earth zinc crystals, offer high strains and high forces with minimally applied magnetic fields, making the material ideally suited for deformable optics applications. For cryogenic temperature applications the use of superconducting magnets offer the possibility of a persistent mode of operation, i.e., the magnetostrictive material will maintain a strain field without power. High temperature superconductors (HTS) are attractive options if the temperature of operation is higher than 10 degrees Kelvin (K) and below 77 K. However, HTS wires have constraints that limit the minimum radius of winding, and even if good wires can be produced, the technology for joining superconducting wires does not exist. In this paper, the design and capabilities of a rare earth zinc magnetostrictive actuator using bulk HTS is described. Bulk superconductors can be fabricated in the sizes required with excellent superconducting properties. Equivalent permanent magnets, made with this inexpensive material, are persistent, do not require a persistent switch as in HTS wires, and can be made very small. These devices are charged using a technique which is similar to the one used for charging permanent magnets, e.g., by driving them into saturation. A small normal conducting coil can be used for charging or discharging. Because of the magnetic field capability of the superconductor material, a very small amount of superconducting magnet material is needed to actuate the rare earth zinc. In this paper, several designs of actuators using YBCO and BSCCO 2212 superconducting materials are presented. Designs that include magnetic shielding to prevent interaction between adjacent actuators will also be described. Preliminary experimental results and comparison with theory for BSCCO 2212 with a magnetostrictive element will be discussed.

Efficient IEC permanent-magnet motor (3 kW) - Final report; Effizienter IEC Permanent-Magnet-Motor (3 kW) - Schlussbericht

Energy Technology Data Exchange (ETDEWEB)

Lindegger, M. [Circle Motor AG, Guemligen (Switzerland); Biner, H. P.; Evequoz, B. [Haute Ecole valaisanne, Sion (Switzerland); Salathe, D. [Hochschule Luzern, Technik und Architektur, Horw (Switzerland)

2008-04-15

Efficient permanent-magnet motors achieve in the area up to 100 kW a higher efficiency than induction machines (standard motors). A simple and fast energy saving option is the exchange of inefficient standard motors. The objective of this work is to install a 3 kW permanent-magnet motor in a standard IEC housing and the optimization of the design for high efficiency. Another objective is the development and the realization of an efficient variable speed control. The efficiency of the motor and the inverter with the control system must be demonstrated by tests. These tasks have been split between Circle Motor AG and the universities of applied sciences of Valais and Lucerne. Considering high-efficiency and low manufacturing cost, a brushless DC solution was adopted. This resulted in an optimum design of the motor and the control system realized with a three-phase rectifier, a buck converter with variable DC voltage, and a three-phase inverter feeding full positive and negative current to two of the legs simultaneously. The maximum measured efficiency is about 96.5% for the inverter and 92% for the motor. With the advantage of the variable speed operation, the efficiency of the realized 3 kW permanent magnet motor together with the control system is always higher than the efficiency of a measured class EFF1 induction motor, even with a direct connection to the grid. The permanent-magnet motor is also about 10 kg lighter. The cost calculation shows that the permanent-magnet motor can be competitive with the induction motor when speed control is desired. This is also the domain with the largest potential for energy savings from variable speed pumps, compressors, fans. (author)

Filtering peripheral high temperature electrons in a cylindrical rf-driven plasmas by an axisymmetric radial magnetic field

Directory of Open Access Journals (Sweden)

Hikaru Akahoshi

2018-03-01

Full Text Available High temperature electrons generated near a radial wall of a cylindrical source tube in a radiofrequency (rf inductively-coupled plasma is filtered by an axisymmetric radial magnetic field formed near the source exit by locating annular permanent magnets, where the axial magnetic field strength in the radially central region is fairly uniform inside the source tube and is close to zero near the source exit. The source is operated at 3 mTorr in argon and the rf antenna is powered by a 13.56 MHz and 400 W rf generator. Measurement of electron energy probability functions shows the presence of the peripheral high temperature electrons inside the source, while the temperature of the peripheral electrons downstream of the source is observed to be reduced.

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.)

Interaction between propulsion and levitation system in the HTSC-permanent magnet conveyance system

International Nuclear Information System (INIS)

Ohashi, S.; Nishio, R.; Hashikawa, T.

2010-01-01

The magnetically levitated conveyance system has been developed. Pinning force of high temperature bulk superconductors (HTSC) are used for the levitation and the guidance of the carrier. The magnetic rail is set on the ground, and flux from the magnetic rail is pinned by HTSCs on the carrier body. To increase the load weight, the repulsive force of the permanent magnet is introduced. The hybrid levitation system is composed. The repulsive force by the permanent magnet between the load stage on the carrier and the magnetic rail on the ground is used to support the load weight. As the load stage is connected to the carrier body by the linear sliders, the mass of the load weight does not act on the carrier body. The interaction between the electromagnet and the permanent magnet under the load stage generates the propulsion force. The electromagnet is constructed by the air core coils, and excited only when the load stage passes. The interaction between the propulsion and the levitation system is investigated. Disturbance of the propulsion system on the levitation and the guidance force is measured. The results show the influence of the propulsion electromagnet on the pinning force is little, and this propulsion system works effectively.

Interaction between propulsion and levitation system in the HTSC-permanent magnet conveyance system

Energy Technology Data Exchange (ETDEWEB)

Ohashi, S., E-mail: ohashi@ipcku.kanasi-u.ac.j [Kansai University 3-3-35, Yamate-cho, Suita, Osaka 564-8680 (Japan); Nishio, R.; Hashikawa, T. [Kansai University 3-3-35, Yamate-cho, Suita, Osaka 564-8680 (Japan)

2010-11-01

The magnetically levitated conveyance system has been developed. Pinning force of high temperature bulk superconductors (HTSC) are used for the levitation and the guidance of the carrier. The magnetic rail is set on the ground, and flux from the magnetic rail is pinned by HTSCs on the carrier body. To increase the load weight, the repulsive force of the permanent magnet is introduced. The hybrid levitation system is composed. The repulsive force by the permanent magnet between the load stage on the carrier and the magnetic rail on the ground is used to support the load weight. As the load stage is connected to the carrier body by the linear sliders, the mass of the load weight does not act on the carrier body. The interaction between the electromagnet and the permanent magnet under the load stage generates the propulsion force. The electromagnet is constructed by the air core coils, and excited only when the load stage passes. The interaction between the propulsion and the levitation system is investigated. Disturbance of the propulsion system on the levitation and the guidance force is measured. The results show the influence of the propulsion electromagnet on the pinning force is little, and this propulsion system works effectively.

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.

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.

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.

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.

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.

Irradiation of Nd-Fe-B permanent magnets with APS bending magnet x-rays and 60Co γ-rays

International Nuclear Information System (INIS)

Alderman, J.; Job, P. K.; Puhl, J.

2000-01-01

The Advanced Photon Source (APS), as well as other third-generation synchrotron light sources, uses permanent magnets in the insertion devices to produce x-rays for scientific research. When placed in a high-energy storage ring, these permanent magnets are subjected to irradiation from synchrotron radiation, high-energy bremsstrahlung, and bremsstrahlung-produced photoneutrons. Previous investigations have exhibited varying degrees of degradation in the intensity of magnetization of these magnets due to irradiation from electron beams, 60 Co γrays, and high-energy neutrons. The APS specifically uses Nd-Fe-B permanent magnets in their insertion devices. Although no detectable radiation-induced demagnetization has been observed in the APS insertion devices so far, partial demagnetization has been observed in at least one insertion device at the European Synchrotron Radiation Facility (ESRF), where Nd-Fe-B permanent magnets are also used

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.

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.

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.

A Novel Integrated Structure with a Radial Displacement Sensor and a Permanent Magnet Biased Radial Magnetic Bearing

Directory of Open Access Journals (Sweden)

Jinji Sun

2014-01-01

Full Text Available In this paper, a novel integrated structure is proposed in order to reduce the axial length of the high speed of a magnetically suspended motor (HSMSM to ensure the maximum speed, which combines radial displacement sensor probes and the permanent magnet biased radial magnetic bearing in HSMSM. The sensor probes are integrated in the magnetic bearing, and the sensor preamplifiers are placed in the control system of the HSMSM, separate from the sensor probes. The proposed integrated structure can save space in HSMSMs, improve the working frequency, reduce the influence of temperature on the sensor circuit, and improve the stability of HSMSMs.

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...

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.

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.

Monte Carlo Simulation Study of Atomic Structure of alnico Permanent Magnets

Science.gov (United States)

Nguyen, Manh Cuong; Wang, Cai-Zhuang; Ho, Kai-Ming

Lattice Monte Carlo simulation based on quinternary cluster expansion energy model is used to investigate nano-scale structure of alnico alloy, which is considered as a candidate material for rare-earth free high performance permanent magnets, especially for high or elevated temperature applications such as electric motor for vehicles. We observe phase decomposition of the master alnico alloy into FeCo-rich magnetic (α1) and NiAl-rich matrix (α2) phases. Concentrations of Fe and Co in α1 phase and Ni and Al in α2 phase are higher for lower annealing temperature. Ti is residing mostly in the α2 phase. The phase boundary between α1 and α2 phases are quite sharp with only few atomic layers. The α1 phase is in B2 ordering with Fe and Al occupying the α-site and Ni and Co occupying the β-site. The α2 phase is in L21 ordering with Al occupying the 4a-site. The phase composition profile again annealing temperature suggests that lower annealing temperature would improve the magnetism of α2 and diminish the magnetism of α2 phase, hence improve shape anisotropy of α1 phase rods and that of alnico.

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

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

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.

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.

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.

Prediction of the new efficient permanent magnet SmCoNiFe3

Science.gov (United States)

Söderlind, P.; Landa, A.; Locht, I. L. M.; Åberg, D.; Kvashnin, Y.; Pereiro, M.; Däne, M.; Turchi, P. E. A.; Antropov, V. P.; Eriksson, O.

2017-09-01

We propose a new efficient permanent magnet, SmCoNiFe3, which is a development of the well-known SmCo5 prototype. More modern neodymium magnets of the Nd-Fe-B type have an advantage over SmCo5 because of their greater maximum energy products due to their iron-rich stoichiometry. Our new magnet, however, removes most of this disadvantage of SmCo5 while preserving its superior high-temperature efficiency over the neodymium magnets. We show by means of first-principles electronic-structure calculations that SmCoNiFe3 has very favorable magnetic properties and could therefore potentially replace SmCo5 or Nd-Fe-B types in various applications.

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

Method for preparing high cure temperature rare earth iron compound magnetic material

Science.gov (United States)

Huang, Yuhong; Wei, Qiang; Zheng, Haixing

2002-01-01

Insertion of light elements such as H,C, or N in the R.sub.2 Fe.sub.17 (R=rare earth metal) series has been found to modify the magnetic properties of these compounds, which thus become prospective candidates for high performance permanent magnets. The most spectacular changes are increases of the Curie temperature, T.sub.c, of the magnetization, M.sub.s, and of coercivity, H.sub.c, upon interstitial insertion. A preliminary product having a component R--Fe--C,N phase is produced by a chemical route. Rare earth metal and iron amides are synthesized followed by pyrolysis and sintering in an inert or reduced atmosphere, as a result of which, the R--Fe--C,N phases are formed. Fabrication of sintered rare earth iron nitride and carbonitride bulk magnet is impossible via conventional process due to the limitation of nitridation method.

Anomalous magneto-structural behavior of MnBi explained: A path towards an improved permanent magnet

Energy Technology Data Exchange (ETDEWEB)

Zarkevich, N. A., E-mail: zarkev@ameslab.gov; Wang, L.-L. [The Ames Laboratory, U.S. Department of Energy, Ames, Iowa 50011 (United States); Johnson, D. D. [The Ames Laboratory, U.S. Department of Energy, Ames, Iowa 50011 (United States); Materials Science and Engineering, Iowa State University, Ames, Iowa 50011 (United States)

2014-03-01

Low-temperature MnBi (hexagonal NiAs phase) exhibits anomalies in the lattice constants (a, c) and bulk elastic modulus (B) below 100 K, spin reorientation and magnetic susceptibility maximum near 90 K, and, importantly for high-temperature magnetic applications, an increasing coercivity (unique to MnBi) above 180  K. We calculate the total energy and magneto-anisotropy energy (MAE) versus (a, c) using DFT+U methods. We reproduce and explain all the above anomalies. We predict that coercivity and MAE increase due to increasing a, suggesting means to improve MnBi permanent magnets.

Anomalous magneto-structural behavior of MnBi explained: A path towards an improved permanent magnet

Energy Technology Data Exchange (ETDEWEB)

Zarkevich, NA; Wang, LL; Johnson, DD

2014-03-01

Low-temperature MnBi (hexagonal NiAs phase) exhibits anomalies in the lattice constants (a, c) and bulk elastic modulus (B) below 100 K, spin reorientation and magnetic susceptibility maximum near 90 K, and, importantly for high-temperature magnetic applications, an increasing coercivity (unique to MnBi) above 180 K. We calculate the total energy and magneto-anisotropy energy (MAE) versus (a, c) using DFT+U methods. We reproduce and explain all the above anomalies. We predict that coercivity and MAE increase due to increasing a, suggesting means to improve MnBi permanent magnets. (C) 2014 Author(s).

RE-Ba-Cu-O for high functional superconducting permanent magnet

International Nuclear Information System (INIS)

Yoo, S.I.; Higuchi, T.; Sakai, N.; Murakami, M.; Fujimoto, H.

1998-01-01

Among various potential applications of melt-textured RE-Ba-Cu-O (REBCO, RE: rare earth elements) superconductors, we have examined the bulk application as the superconducting permanent magnet, especially for the magnetically-levitated (MAGLEV) train. Compared with Y-Ba-Cu-O (YBCO), oxygen-controlled melt-growth (OCMG)-processed LREBCO (LRE: light rare earth elements) bulk superconductors are more promising for this application because of larger critical current density (J c ) values in high field and higher irreversibility field (B irr ) within the range of the liquid nitrogen refrigeration (63-77 K), implying that even higher trapped fields (B t ) are achievable in principle. In this paper, material requirements of superconducting bulks for the MAGLEV train are first presented and then processing aspects for the fabrication of good LREBCO bulks are described. (orig.)

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...

Analysis and design of a slotless tubular permanent magnet actuator for high acceleration applications

NARCIS (Netherlands)

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

2009-01-01

This paper presents the design of a linear actuator for high acceleration applications. In the analysis, a slotless tubular permanent magnet actuator is modeled by means of semianalytical field solutions. Several slotless topologies are modeled and compared to achieve the highest acceleration. A

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...

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

Local Magnetic Measurements of Trapped Flux Through a Permanent Current Path in Graphite

Science.gov (United States)

Stiller, Markus; Esquinazi, Pablo D.; Quiquia, José Barzola; Precker, Christian E.

2018-04-01

Temperature- and field-dependent measurements of the electrical resistance of different natural graphite samples suggest the existence of superconductivity at room temperature in some regions of the samples. To verify whether dissipationless electrical currents are responsible for the trapped magnetic flux inferred from electrical resistance measurements, we localized them using magnetic force microscopy on a natural graphite sample in remanent state after applying a magnetic field. The obtained evidence indicates that at room temperature a permanent current flows at the border of the trapped flux region. The current path vanishes at the same transition temperature T_c≈ 370 K as the one obtained from electrical resistance measurements on the same sample. This sudden decrease in the phase is different from what is expected for a ferromagnetic material. Time-dependent measurements of the signal show the typical behavior of flux creep of a permanent current flowing in a superconductor. The overall results support the existence of room-temperature superconductivity at certain regions in the graphite structure and indicate that magnetic force microscopy is suitable to localize them. Magnetic coupling is excluded as origin of the observed phase signal.

Eddy current loss calculation and thermal analysis of axial-flux permanent magnet couplers

Directory of Open Access Journals (Sweden)

Di Zheng

2017-02-01

Full Text Available A three-dimensional magnetic field analytical model of axial-flux permanent magnet couplers is presented to calculate the eddy current loss, and the prediction of the copper plate temperature under various loads is analyzed. The magnetic field distribution is calculated, and then the eddy current loss is obtained, with the magnetic field analytical model established in cylindrical coordinate. The influence of various loads on eddy current loss is analyzed. Furthermore, a thermal model of axial-flux permanent magnet couplers is established by taking the eddy current loss as the heat source, using the electromagnetic-thermal coupled method. With the help of the thermal model, the influence of various loads on copper plate temperature rise is also analyzed. The calculated results are compared with the results of finite element method and measurement. The comparison results confirm the validity of the magnetic field analytical model and thermal model.

High temperature superconductor accelerator magnets

NARCIS (Netherlands)

van Nugteren, J.

2016-01-01

For future particle accelerators bending dipoles are considered with magnetic fields exceeding 20T. This can only be achieved using high temperature superconductors (HTS). These exhibit different properties from classical low temperature superconductors and still require significant research and

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.

High temperature superconductor cable concepts for fusion magnets

CERN Document Server

AUTHOR|(CDS)2078397

2013-01-01

Three concepts of high temperature superconductor cables carrying kA currents (RACC, CORC and TSTC) are investigated, optimized and evaluated in the scope of their applicability as conductor in fusion magnets. The magnetic field and temperature dependence of the cables is measured; the thermal expansion and conductivity of structure, insulation and filling materials are investigated. High temperature superconductor winding packs for fusion magnets are calculated and compared with corresponding low temperature superconductor cases.

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

Development of Disk Rover, wall-climbing robot using permanent magnet disk

International Nuclear Information System (INIS)

Hirose, Shigeo; Tsutsumitake; Hiroshi; Toyama, Ryousei; Kobayashi, Kengo.

1992-01-01

A new type of wall climbing robot, named Disk Rover, using permanent magnet disks are developed. The newly introduced permanent magnet disk is to rotate the magnet disk on the surface of wall with partly contacted posture. It allows to produce high magnetic attraction force compared with conventional permanent wheel which utilizes only a small portion of the magnet installed around the wheel. The optimum design of the magnetic wheel is done by using finit element method and it is shown that the magnetic attraction force vs. weight ratio can be designed about three times higher than conventional type magnet wheel. The developed Disk Rover is 25 kg in weight including controller and battery, about 685 mm in diameter, 239 mm in height and has a pair of permanent magnet disks. It is demonstrated by the experiments that the Disk Rover can move around on the surface of the wall quite smoothly by radio control and has payload of about its own weight. Several considerations are also done in order to surmount bead weld. (author)

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...

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

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.

Field cooling of a MgB2 cylinder around a permanent magnet stack: prototype for superconductive magnetic bearing

International Nuclear Information System (INIS)

Perini, E; Giunchi, G

2009-01-01

The behaviour of bulk superconductors as levitators of permanent magnets (PMs) has been extensively studied for the textured YBCO high-temperature superconductor material, in the temperature range lower than 77 K, obtaining extremely high trapped fields but also experiencing limitations on the mechanical characteristics of the material and on the possibility to produce large objects. Alternatively, bulk MgB 2 , even if it is superconducting at lower temperatures, has fewer mechanical problems, when fully densified, and presents stable magnetization in the temperature range between 10 and 30 K. With the reactive Mg-liquid infiltration technique we have produced dense MgB 2 bulk cylinders of up to 65 mm diameter and 100 mm height. This kind of cylinder can be consider as a prototype of a passive magnetic bearing for flywheels or other rotating electrical machines. We have conductively cooled one of these superconducting cylinders inside a specially constructed cryostat, and the levitation forces and stiffness, with respect to axial movements of various arrangements of the PM, have been measured as a function of the temperature below T c . We verified the very stable characteristics of the induced magnetization after several cycles of relative movements of the PM and the superconducting cylinder.

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

The vortex structure and flux creep within superconducting permanent-magnet high aspect-ratio discs

International Nuclear Information System (INIS)

Watson, J.H.P.; Younas, I.

1997-01-01

Inhomogeneous type II superconducting discs magnetized by an applied field will retain some magnetization when field is switched off so the superconducting disc will behave as a permanent magnet after flux creep has reduced to a low value.This paper examines the superconducting vortex structure within superconducting permanent-magnet high aspect-ratio discs which is consistent with the calculated magnetic field distribution.The discs, with radius R, have the axis along the z-direction and the mid-plane of the disc corresponds to z = 0. These discs with large aspect ratios in the remnant state have a region between radius r l and R where the magnetic field is reversed. Surrounding the line r = r l and z = 0 there is a region where H cl which is in the Meissner state. Near r l the vortex lines are strongly curved. For radii r l vortex lines creep to larger values of r. For radii r > r l vortex lines creep to smaller values of r, meet at r l with vortex lines of opposite sign and form a continuous loop which decreases in size and is finally annihilated in the Meissner region. Flux creep induces lossless currents in the Meissner region. (author)

High Temperature Superconductor Accelerator Magnets

CERN Document Server

AUTHOR|(CDS)2079328; de Rijk, Gijs; Dhalle, Marc

2016-11-10

For future particle accelerators bending dipoles are considered with magnetic fields exceeding $20T$. This can only be achieved using high temperature superconductors (HTS). These exhibit different properties from classical low temperature superconductors and still require significant research and development before they can be applied in a practical accelerator magnet. In order to study HTS in detail, a five tesla demonstrator magnet named Feather-M2 is designed and constructed. The magnet is based on ReBCO coated conductor, which is assembled into a $10kA$ class Roebel cable. A new and optimized Aligned Block layout is used, which takes advantage of the anisotropy of the conductor. This is achieved by providing local alignment of the Roebel cable in the coil windings with the magnetic field lines. A new Network Model capable of analyzing transient electro-magnetic and thermal phenomena in coated conductor cables and coils is developed. This model is necessary to solve critical issues in coated conductor ac...

Three-Dimensional Temperature Field Calculation and Analysis of an Axial-Radial Flux-Type Permanent Magnet Synchronous Motor

Directory of Open Access Journals (Sweden)

Dong Li

2018-05-01

Full Text Available This article concentrates on the steady-state thermal characteristics of the Axial-Radial Flux-Type Permanent Magnet Synchronous Motor (ARFTPMSM. Firstly, the three-dimensional mathematical models for electromagnetic calculation and analyses are established, and the machine loss, including the stator loss, armature winding loss, rotor loss, and axial structure loss is calculated by using time-step Finite Element Method (FEM. Then, the loss distribution is assigned as the heat source for the thermal calculation. Secondly, the mathematical model for thermal calculation is also established. The assumptions and the boundary conditions are proposed to simplify the calculation and to improve convergence. Thirdly, the three-dimensional electromagnetic and thermal calculations of the machine, of which the armature winding and axial field winding are developed by using copper wires, are solved, from which the temperature distributions of the machine components are obtained. The experiments are carried out on the prototype with copper wires to validate the accuracy of the established models. Then, the temperature distributions of machine components under different Axial Magnetic Motive Force (AMMF are investigated. Since the machine is finally developing by using HTS wires, the temperature distributions of machine developed by utilizing High Temperature Superconducting (HTS wires, are also studied. The temperature distribution differences of the machine developed by using copper wires and HTS wires are drawn. All of these above will provide a helpful reference for the thermal calculation of the ARFTPMSM, as well as the design of the HTS coils and the cryogenic cooling system.

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.

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.

Dynamic response characteristics of high temperature superconducting maglev systems: Comparison between Halbach-type and normal permanent magnet guideways

International Nuclear Information System (INIS)

Wang, B.; Zheng, J.; Che, T.; Zheng, B.T.; Si, S.S.; Deng, Z.G.

2015-01-01

Highlights: • The loading weight affects the RF tremendously. • Reducing the FCH can improve the stability of the maglev vehicle. • The Halbach-type PMG has better loading capacity than the conventional PMG. • Pre-load is an effective way to enhance the dynamic characteristic of the HTS maglev vehicle. - Abstract: The permanent magnet guideway (PMG) is very important for the performance of the high temperature superconducting (HTS) system in terms of electromagnetic force and operational stability. The dynamic response characteristics of a HTS maglev model levitating on two types of PMG, which are the normal PMG with iron flux concentration and Halbach-type PMG, were investigated by experiments. The dynamic signals for different field-cooling heights (FCHs) and loading/unloading processes were acquired and analyzed by a vibration analyzer and laser displacement sensors. The resonant frequency, stiffness and levitation height of the model were discussed. It was found that the maglev model on the Halbach-type PMG has higher resonant frequency and higher vertical stiffness compared with the normal PMG. However, the low lateral stiffness of the model on the Halbach-type PMG indicates poor lateral stability. Besides, the Halbach-type PMG has better loading capacity than the normal PMG. These results are helpful to design a suitable PMG for the HTS system in practical applications.

Dynamic response characteristics of high temperature superconducting maglev systems: Comparison between Halbach-type and normal permanent magnet guideways

Energy Technology Data Exchange (ETDEWEB)

Wang, B. [Applied Superconductivity Laboratory, State Key Laboratory of Traction Power, Southwest Jiaotong University, Chengdu 610031, P R China (China); Zheng, J., E-mail: jzheng@swjtu.cn [Applied Superconductivity Laboratory, State Key Laboratory of Traction Power, Southwest Jiaotong University, Chengdu 610031, P R China (China); Che, T. [Applied Superconductivity Laboratory, State Key Laboratory of Traction Power, Southwest Jiaotong University, Chengdu 610031, P R China (China); Zheng, B.T.; Si, S.S. [Applied Superconductivity Laboratory, State Key Laboratory of Traction Power, Southwest Jiaotong University, Chengdu 610031, P R China (China); School of Electrical Engineering, Southwest Jiaotong University, Chengdu 610031, P R China (China); Deng, Z.G., E-mail: deng@swjtu.cn [Applied Superconductivity Laboratory, State Key Laboratory of Traction Power, Southwest Jiaotong University, Chengdu 610031, P R China (China)

2015-12-15

Highlights: • The loading weight affects the RF tremendously. • Reducing the FCH can improve the stability of the maglev vehicle. • The Halbach-type PMG has better loading capacity than the conventional PMG. • Pre-load is an effective way to enhance the dynamic characteristic of the HTS maglev vehicle. - Abstract: The permanent magnet guideway (PMG) is very important for the performance of the high temperature superconducting (HTS) system in terms of electromagnetic force and operational stability. The dynamic response characteristics of a HTS maglev model levitating on two types of PMG, which are the normal PMG with iron flux concentration and Halbach-type PMG, were investigated by experiments. The dynamic signals for different field-cooling heights (FCHs) and loading/unloading processes were acquired and analyzed by a vibration analyzer and laser displacement sensors. The resonant frequency, stiffness and levitation height of the model were discussed. It was found that the maglev model on the Halbach-type PMG has higher resonant frequency and higher vertical stiffness compared with the normal PMG. However, the low lateral stiffness of the model on the Halbach-type PMG indicates poor lateral stability. Besides, the Halbach-type PMG has better loading capacity than the normal PMG. These results are helpful to design a suitable PMG for the HTS system in practical applications.

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.

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...

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.

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.

Development of Thermoelectric and Permanent Magnet Nanoparticles for Clean Energy Applications

Science.gov (United States)

Nguyen, Phi-Khanh

thermoelectric power factor. Such a technique is essential for providing inexpensive, oxidation-free nanoparticles required for fabricating high performance thermoelectric devices for power generation from waste heat, and for refrigeration. We have investigated the spark erosion of MnBi, a promising rare-earth-free permanent magnet, and have determined that spark erosion provides the best approach for producing MnBi particles. The low-temperature phase of MnBi (LTP-MnBi) is an attractive rare-earth free permanent magnet material due it its high uniaxial magnetocrystalline anisotropy, which produces an unusually high coercivity at the elevated temperatures required for motor and generators. However, due to the peritectic Mn-Bi phase diagram and the slow interdiffusion of Mn and Bi below the 350°C phase change temperature, bulk samples of LTP-MnBi with high saturation magnetization (MS) have been difficult to achieve. In Chapter 3, we describe the successful formation of high-purity bulk LTP-MnBi ingots and spark erosion of this material to produce single-domain particles of MnBi at an unprecedented rate. The bulk ingots have MS > 90 wt % of LTP-MnBi, and are formed by chill-casting and by vacuum-annealing of arc-melted ingots. The as-prepared powder then consists of amorphous, crystalline, and superparamagnetic particles, mostly as porous aggregates. The major fraction of the powder consists of 20--30 nm particles. A short anneal crystallizes the amorphous particles producing a high moment, albeit with HC of only a few kOe. If lightly milled, the agglomerates are broken up and yield an HC of 1 T and a maximum energy product of 3.0 MGOe. The particles can be further engineered through milling, annealing, and/or solution processing in order to produce unique properties that hold promise to achieving the first bulk permanent magnet that utilizes the exchange-spring principle. In addition, we have found that due to the amorphous component of the spark-eroded powder, a cold compact

Vibrational Properties of High- Superconductors Levitated Above a Bipolar Permanent Magnetic Guideway

Science.gov (United States)

Liu, Lu; Wang, Jiasu

2014-05-01

A bipolar permanent magnetic guideway (PMG) has a unique magnetic field distribution profile which may introduce a better levitation performance and stability to the high- superconducting (HTS) maglev system. The dynamic vibration properties of multiple YBCO bulks arranged into different arrays positioned above a bipolar PMG and free to levitate were investigated. The acceleration and resonance frequencies were experimentally measured, and the stiffness and damping coefficients were evaluated for dynamic stability. Results indicate that the levitation stiffness is closely related to the field-cooling-height and sample positioning. The damping ratio was found to be low and nonlinear for the Halbach bipolar HTS-PMG system.

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

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.

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}.

Design of spoke type motor and magnetizer for improving efficiency based rare-earth-free permanent-magnet motor

Science.gov (United States)

Kim, Young Hyun; Cheon, Byung Chul; Lee, Jung Ho

2018-05-01

This study proposes criteria for both optimal-shape and magnetizer-system designs to be used for a high-output spoke-type motor. The study also examines methods of reducing high-cogging torque and torque ripple, to prevent noise and vibration. The optimal design of the stator and rotor can be enhanced using both a response surface method and finite element method. In addition, a magnetizer system is optimally designed for the magnetization of permanent magnets for use in the motor. Finally, this study verifies that the proposed motor can efficiently replace interior permanent magnet synchronous motor in many industries.

Design of spoke type motor and magnetizer for improving efficiency based rare-earth-free permanent-magnet motor

Directory of Open Access Journals (Sweden)

Young Hyun Kim

2018-05-01

Full Text Available This study proposes criteria for both optimal-shape and magnetizer-system designs to be used for a high-output spoke-type motor. The study also examines methods of reducing high-cogging torque and torque ripple, to prevent noise and vibration. The optimal design of the stator and rotor can be enhanced using both a response surface method and finite element method. In addition, a magnetizer system is optimally designed for the magnetization of permanent magnets for use in the motor. Finally, this study verifies that the proposed motor can efficiently replace interior permanent magnet synchronous motor in many industries.

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

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.

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

Modeling forces in high-temperature superconductors

International Nuclear Information System (INIS)

Turner, L. R.; Foster, M. W.

1997-01-01

We have developed a simple model that uses computed shielding currents to determine the forces acting on a high-temperature superconductor (HTS). The model has been applied to measurements of the force between HTS and permanent magnets (PM). Results show the expected hysteretic variation of force as the HTS moves first toward and then away from a permanent magnet, including the reversal of the sign of the force. Optimization of the shielding currents is carried out through a simulated annealing algorithm in a C++ program that repeatedly calls a commercial electromagnetic software code. Agreement with measured forces is encouraging

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)

ULF-NMR system using HTS-SQUID and permanent magnet

Energy Technology Data Exchange (ETDEWEB)

Fukumoto, Shohei, E-mail: hatukade@ens.tut.ac.jp [Toyohashi University of Technology, 1-1 Hibarigaoka, Tempaku-cho, Toyohashi, Aichi 441-8580 (Japan); Tsunaki, Shingo; Chigasaki, Takumi; Hatsukade, Yoshimi; Tanaka, Saburo [Toyohashi University of Technology, 1-1 Hibarigaoka, Tempaku-cho, Toyohashi, Aichi 441-8580 (Japan)

2013-01-15

Highlights: ► A permanent magnet was introduced into a ULF SQUID-NMR system for polarization. ► An instrument to transfer a sample in the magnet to under a SQUID was implemented. ► An AC pulse coil was also introduced to apply a π/2 pulse to obtain an NMR signal. ► A {sup 1}H NMR signal was measured while applying a static field of 45 μT. ► The signal to noise ratio of the {sup 1}H NMR signal was about 100. -- Abstract: We have constructed an ultra-low field (ULF) nuclear magnetic resonance (NMR)/magnetic resonance imaging (MRI) system using an HTS-rf-SQUID and room-temperature electromagnets in a magnetically shielded room (MSR). In this study, in order to improve the signal to noise ratio (S/N) of the system, we introduced a permanent magnet instead of the electromagnet for pre-polarizing the sample to enhance the pre-polarizing field (B{sub p}). The cylindrical permanent magnet of 270 mT was used to magnetize a water sample for several seconds outside the MSR and about 1.5 m away from the SQUID. We constructed an instrument to transfer the magnetized sample from the permanent magnet to under the SQUID in 0.5 s. Since the non-adiabatic condition cannot be kept in such sample transfer scheme, an AC pulse coil to apply an AC pulse field B{sub AC} to rotate the magnetization moments for π/2 was introduced to measure a free induction decay (FID) signal from the sample. By this system, we obtained an NMR signal from the water sample of 10 ml while applying a static field of 45 μT and π/2 pulse after the transfer. The S/N of the NMR spectrum was about 100 by a single shot, which was 10 times larger than that obtained with the electromagnet of 32 mT. In addition, we demonstrated the measurements of the longitudinal relaxation time (T{sub 1}) and the spin echo signal of the water sample by the system.

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

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.

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.

Performance Comparison between a Permanent Magnet Synchronous Motor and an Induction Motor as a Traction Motor for High Speed Train

Science.gov (United States)

Kondo, Minoru; Kawamura, Junya; Terauchi, Nobuo

Performance tests are carried out to demonstrate the superiority of a permanent magnet synchronous motor to an induction motor as a traction motor for high-speed train. A prototype motor was manufactured by replacing the rotor of a conventional induction motor. The test results show that the permanent magnet motor is lighter, efficient and more silent than the induction motor because of the different rotor structure.

Study of a permanent-magnet dipole with variable field strength and polarity

International Nuclear Information System (INIS)

Honma, Toshihiro

1996-01-01

A proto-type dipole magnet employing permanent-magnet rods has been designed and constructed. The magnet is able to change the magnetic field strength continuously as well as the polarity of the field direction by rotating the rods. The magnet has a special advantage of high-field production within a small open space available. The magnet of this type will be used for beam steering at an extraction channel for a planned negative-ion acceleration in our cyclotron. The first important objective at the exit channel is to steer the beam extracted from the cyclotron by some dipole magnet onto the optical axis of a new beam line to be constructed. This is not a trivial task because available open space is too small to install a coil-type magnet. One of the selections is to use a permanent-magnet dipole because such a magnet is expected to provide a very high field in a small space when compared with a coil-type magnet. A proto-type permanent-magnet dipole (PMD) with variable field strength and polarity has been designed and constructed for such a purpose. (J.P.N.)

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.

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.

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.

Irradiated radiation dose measurements of multilayer mirrors and permanent magnets used at FELI facilities

International Nuclear Information System (INIS)

Wakisaka, K.; Tongu, H.; Okuma, S.; Oshita, E.; Wakita, K.; Takii, T.; Tomimasu, Takio

1997-01-01

Recently the operation time of the free electron laser (FEL) user's facilities is close on three thousand hours per year. Cavity mirrors of their optical resonators and permanent magnets of their undulators are used under high intensity radiation field along their high current electron beam lines. Among these mirrors and permanent magnets, multilayer mirrors and Nd-Fe-B permanent magnets are not so strong against radiation damage compared with Au-coated copper mirrors and Sm-Co permanent magnets. A radiation damage on Ta 2 O 5 /SiO 2 mirrors was found for the first time after about fifty hours visible FEL operation at the FELI. The damage is due to irradiated bremsstrahlung and intracavity FEL. However, radiation damages on Nd-Fe-B permanent magnets were already reported compared with Sm-Co ones using high energy neutrons, protons, deuterons and 60 Coγ-rays. Mixed irradiation effects of 85-MeV electrons, bremsstrahlung and 60 Coγ-rays and of 17-MeV electrons and 60 Coγ-rays were also studied. The latest results show that the magnetic flux loss of Nd-Fe-B is 2% at an absorbed dose of 10 MGy. The present work was carried out to study the irradiated dose distributions near the multilayer mirrors and Nd-Fe-B permanent magnets with thermoluminescence dosimeters (TLDs). The irradiated dose to the cavity mirrors used in Linac-based FEL experiment is estimated to be 0.3 MGray for fifty hours irradiation. The irradiated dose to the Nd-Fe-B magnets is estimated to be 16 MGray for 2 thousand hours operation. The decrease of their magnetic flux due to 16 MGray is estimated to be about 3%. These dose monitorings are useful to reduce irradiated dosages to the mirrors and the permanent magnets as low as possible and to estimate their safety lifetimes. (author)

A permanently magnetized high gradient magnetic filter for glove-box cleaning and increasing HEPA filter life

International Nuclear Information System (INIS)

Watson, J.H.P.; Boorman, C.H.

1991-01-01

The purpose of this paper is to describe the structure and testing of a permanently magnetized magnetic filter on simulants for radioactive material. The experimental work was carried out at British Nuclear Fuels plc, Sellafield, England and in CEN/SCK, Mol, Belgium using Cr powder which is a good magnetic simulant for PuO 2 . The basis of the use of such a filter in the nuclear industry relies on the fact that much of the radioactive material is paramagnetic. In the last twenty years a separation technique has been developed which allows weakly paramagnetic particles of colloidal size to be separated from fluid which passes through the separator. This method is called high gradient magnetic separation (HGMS) and is accomplished by magnetizing a fine ferromagnetic wire matrix by an externally applied magnetic field. This paper describes a new approach to this problem, by using a magnetically hysteretic material to construct the ferromagnetic matrix, it has been possible to provide a magnetic field in the region of the matrix and also have a residual magnetization within the matrix. This provides extremely compact magnetic separation systems. There are some subtle differences between this separation system and conventional HGMS which makes the radial feed system, with all its advantages, almost mandatory for hysteretic HGMS

Processing and Protection of Rare Earth Permanent Magnet Particulate for Bonded Magnet Applications

Energy Technology Data Exchange (ETDEWEB)

Sokolowski, Peter Kelly [Iowa State Univ., Ames, IA (United States)

2007-01-01

Rapid solidification of novel mixed rare earth-iron-boron, MRE₂Fe₁₄B (MRE = Nd, Y, Dy; currently), magnet alloys via high pressure gas atomization (HPGA) have produced similar properties and structures as closely related alloys produced by melt spinning (MS) at low wheel speeds. Recent additions of titanium carbide and zirconium to the permanent magnet (PM) alloy design in HPGA powder (using He atomization gas) have made it possible to achieve highly refined microstructures with magnetic properties approaching melt spun particulate at cooling rates of 10⁵-10⁶K/s. By producing HPGA powders with the desirable qualities of melt spun ribbon, the need for crushing ribbon was eliminated in bonded magnet fabrication. The spherical geometry of HPGA powders is more ideal for processing of bonded permanent magnets since higher loading fractions can be obtained during compression and injection molding. This increased volume loading of spherical PM powder can be predicted to yield a higher maximum energy product (BH)_max for bonded magnets in high performance applications. Passivation of RE-containing powder is warranted for the large-scale manufacturing of bonded magnets in applications with increased temperature and exposure to humidity. Irreversible magnetic losses due to oxidation and corrosion of particulates is a known drawback of RE-Fe-B based alloys during further processing, e.g. injection molding, as well as during use as a bonded magnet. To counteract these effects, a modified gas atomization chamber allowed for a novel approach to in situ passivation of solidified particle surfaces through injection of a reactive gas, nitrogen trifluoride (NF₃). The ability to control surface chemistry during atomization processing of fine spherical RE-Fe-B powders produced advantages over current processing methodologies. In particular, the capability to coat particles while 'in flight' may eliminate the

Numerical simulation of permanent magnet method: Influence of experimental conditions on accuracy of j{sub C}-distribution

Energy Technology Data Exchange (ETDEWEB)

Takayama, T., E-mail: takayama@yz.yamagata-u.ac.j [Faculty of Engineering, Yamagata University, 4-3-16, Johnan, Yonezawa, Yamagata 992-8510 (Japan); Kamitani, A.; Tanaka, A. [Graduate School of Science and Engineering, Yamagata University, 4-3-16, Johnan, Yonezawa, Yamagata 992-8510 (Japan)

2010-11-01

Influence of the magnet position on the determination of the distribution of the critical current density in a high-temperature superconducting (HTS) thin film has been investigated numerically. For this purpose, a numerical code has been developed for analyzing the shielding current density in a HTS sample. By using the code, the permanent magnet method is reproduced. The results of computations show that, even if the center of the permanent magnet is located near the film edge, the maximum repulsive force is roughly proportional to the critical current density. This means that the distribution of the critical current density in the HTS film can be estimated from the proportionality constants determined by using the relations between the maximum repulsive force and the critical current density.

Probing High Temperature Superconductors with Magnetometry in Ultrahigh Magnetic Fields

Energy Technology Data Exchange (ETDEWEB)

Li, Lu [Univ. of Michigan, Ann Arbor, MI (United States)

2017-07-26

The objective of this research is to investigate the high-field magnetic properties of high temperature superconductors, materials that conduct electricity without loss. A technique known as high-resolution torque magnetometry that was developed to directly measure the magnetization of high temperature superconductors. This technique was implemented using the 65 Tesla pulsed magnetic field facility that is part of the National High Magnetic Field Laboratory at Los Alamos National Laboratory. This research addressed unanswered questions about the interplay between magnetism and superconductivity, determine the electronic structure of high temperature superconductors, and shed light on the mechanism of high temperature superconductivity and on potential applications of these materials in areas such as energy generation and power transmission. Further applications of the technology resolve the novel physical phenomena such as correlated topological insulators, and spin liquid state in quantum magnets.

A study of flux control for high-efficiency speed control of variable flux permanent magnet motor

Science.gov (United States)

Kim, Young Hyun; Lee, Seong Soo; Lee, Jung Ho

2018-05-01

In this study, we evaluate the performance of permanent magnets (PMs). The efficiency of attraction in the high speed region was studied using the variable flux memory motor (VFMM). It is presented in order to analyze the magnetic characteristics of PMs, using the second quadrant plan data with re- and de-magnetization. In addition, this study focuses on the evaluation of operational characteristics relative to the magnetizing directions according to the d-axis currents, by using one of the finite element solutions. The feasibility of application for the VFMM has been experimentally demonstrated.

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)

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)

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.

Evolution strategies and multi-objective optimization of permanent magnet motor

DEFF Research Database (Denmark)

Andersen, Søren Bøgh; Santos, Ilmar

2012-01-01

When designing a permanent magnet motor, several geometry and material parameters are to be defined. This is not an easy task, as material properties and magnetic fields are highly non-linear and the design of a motor is therefore often an iterative process. From an engineering point of view, we...... of evolution strategies, ES to effectively design and optimize parameters of permanent magnet motors. Single as well as multi-objective optimization procedures are carried out. A modified way of creating the strategy parameters for the ES algorithm is also proposed and has together with the standard ES...

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...

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.

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

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.

Numerical investigations on applicability of permanent magnet method to crack detection in HTS film

Energy Technology Data Exchange (ETDEWEB)

Kamitani, A., E-mail: kamitani@yz.yamagata-u.ac.jp [Yamagata University, 4-3-16, Johnan, Yonezawa, Yamagata 992-8510 (Japan); Takayama, T. [Yamagata University, 4-3-16, Johnan, Yonezawa, Yamagata 992-8510 (Japan); Saitoh, A. [University of Hyogo, 2167, Shosha, Himeji, Hyogo 671-2280 (Japan)

2014-09-15

Highlights: • The defect parameter is defined for characterizing a crack position. • The defect parameter shows a remarkable change only near a crack. • A crack detection method is proposed on the basis of the permanent-magnet method. • The high-speed rough detection can be achieved by means of the proposed method. - Abstract: The scanning permanent-magnet (PM) method was originally developed for determining the spatial distribution of the critical current density in a high-temperature superconducting (HTS) film. In the present study, its applicability to the crack detection in an HTS film is investigated numerically. To this end, a defect parameter is defined for characterizing a crack position and it is calculated along various scanning lines. The results of computations show that, only when the scanning position is near a crack, the defect parameter shows a violent change. On the basis of the behavior of the defect parameter, the method for roughly identifying a crack is also proposed.

Numerical investigations on applicability of permanent magnet method to crack detection in HTS film

International Nuclear Information System (INIS)

Kamitani, A.; Takayama, T.; Saitoh, A.

2014-01-01

Highlights: • The defect parameter is defined for characterizing a crack position. • The defect parameter shows a remarkable change only near a crack. • A crack detection method is proposed on the basis of the permanent-magnet method. • The high-speed rough detection can be achieved by means of the proposed method. - Abstract: The scanning permanent-magnet (PM) method was originally developed for determining the spatial distribution of the critical current density in a high-temperature superconducting (HTS) film. In the present study, its applicability to the crack detection in an HTS film is investigated numerically. To this end, a defect parameter is defined for characterizing a crack position and it is calculated along various scanning lines. The results of computations show that, only when the scanning position is near a crack, the defect parameter shows a violent change. On the basis of the behavior of the defect parameter, the method for roughly identifying a crack is also proposed

Nd{sub 2}Fe{sub 14}B and Pr{sub 2}Fe{sub 14}B magnets characterisation and modelling for cryogenic permanent magnet undulator applications

Energy Technology Data Exchange (ETDEWEB)

Benabderrahmane, C., E-mail: chamseddine.benabderrahmane@synchrotron-soleil.fr [Synchrotron SOLEIL, St Aubin (France); Berteaud, P.; Valleau, M.; Kitegi, C.; Tavakoli, K.; Bechu, N.; Mary, A.; Filhol, J.M.; Couprie, M.E. [Synchrotron SOLEIL, St Aubin (France)

2012-03-21

Cryogenic permanent magnet undulators take benefit from improved magnetic properties of RE{sub 2}Fe{sub 14}B (Rare Earth based magnets) at cryogenic temperatures for achieving short period high magnetic field. In particular, using Praseodymium instead of Neodymium generally employed for insertion devices avoids limitation due to Spin Reorientation Transition phenomenon. Magnetic properties of magnet samples (Nd{sub 2}Fe{sub 14}B and Pr{sub 2}Fe{sub 14}B) versus temperature have been investigated and applied to a 20 mm period Nd{sub 2}Fe{sub 14}B (BH50) and to a 18 mm period Pr{sub 2}Fe{sub 14}B (CR53) systems. Four period undulators have been built, characterised and compared to the models.

Numerical solutions to the critical state in a magnet-high temperature superconductor interaction

Energy Technology Data Exchange (ETDEWEB)

Ruiz-Alonso, D; Coombs, T A; Campbell, A M [Cambridge University Engineering Department, Trumpington Street, Cambridge CB2 1PZ (United Kingdom)

2005-02-01

This paper presents an algorithm to simulate the electromagnetic behaviour of devices containing high temperature superconductors in axially symmetric problems. The numerical method is built within the finite element method. The electromagnetic properties of HTSCs are described through the critical-state model. Measurements of the axial force between a permanent magnet and a melt-textured YBCO puck are obtained in order to validate the method. This simple system is modelled so that the proposed method obtains the current distribution and electromagnetic fields in the HTSC. The forces in the interaction between the magnet and the HTSC puck can then be calculated. A comparison between experimental and simulation results shows good matching. The simplification of using the critical-state model and ignoring flux creep in this type of configuration is also explored.

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....

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.

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.

A High Torque Segmented Outer Rotor Permanent Magnet Flux Switching Motor for Motorcycle Propulsion

Directory of Open Access Journals (Sweden)

Mbadiwe I Enwelum

2018-01-01

Full Text Available Electric scooters also known as electric motorcycle are viable and personal means of road transportation have been making their ways into the world markets now because in them, combustion engine with the use of fuel oil for propulsion have been completely eliminated for economic and environmental imperatives. Electric motor which converts electrical energy into mechanical energy is used to overcome the complication of combustion engine. As it is, everyone is opting for combustion engine free and fuel-less type of vehicle. For this reason, manufacturers have exhibited interest, making research on electric motor very attractive. Meanwhile, surface permanent magnet synchronous motor (SPMSM has been successfully developed having output torque of 110 Nm, the assembly of motor lacked mechanical strength between the rotor yoke and the mounted permanent magnet (PM which heats up during speed operation, resulting to poor performance. To overcome the challenges laced with SPMSM, this paper presents a novel design of 24 stator 14 pole outer rotor-permanent magnet flux switching motor (SOR-PMFSM capable of high torque and high performance. It employs an unconventional segmented rotor which has short flux path flow. It also embraces alternate stator tooth windings to reduce material cost. Design specifications and restriction with input DC current are the same with SPMSM. The 2D-FEA by JMAG, version 14 is used to examine the performance of the proposed motor in terms of cogging torque, back-emf, average torque, power and efficiency. Preliminary results showed that torque, power output and efficiency of the proposed motor are 1.9Nm times, 5.8kW times more than SPMSM and efficiency of 84% thus, can sustain acceleration for long distance travel.

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)

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

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.

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,

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

A study of flux control for high-efficiency speed control of variable flux permanent magnet motor

Directory of Open Access Journals (Sweden)

Young Hyun Kim

2018-05-01

Full Text Available In this study, we evaluate the performance of permanent magnets (PMs. The efficiency of attraction in the high speed region was studied using the variable flux memory motor (VFMM. It is presented in order to analyze the magnetic characteristics of PMs, using the second quadrant plan data with re- and de-magnetization. In addition, this study focuses on the evaluation of operational characteristics relative to the magnetizing directions according to the d-axis currents, by using one of the finite element solutions. The feasibility of application for the VFMM has been experimentally demonstrated.

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...

Cryocooler applications for high-temperature superconductor magnetic bearings

International Nuclear Information System (INIS)

Niemann, R. C.

1998-01-01

The efficiency and stability of rotational magnetic suspension systems are enhanced by the use of high-temperature superconductor (HTS) magnetic bearings. Fundamental aspects of the HTS magnetic bearings and rotational magnetic suspension are presented. HTS cooling can be by liquid cryogen bath immersion or by direct conduction, and thus there are various applications and integration issues for cryocoolers. Among the numerous cryocooler aspects to be considered are installation; operating temperature; losses; and vacuum pumping

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)

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.

A Cryogenic Magnetostrictive Actuator using a Persistent High Temperature Superconducting Magnet, Part 1: Concept and Design. Part 1; Concept and Design

Science.gov (United States)

Horner, Garnett C.; Bromberg, Leslie; Teter, J. P.

2001-01-01

Cryogenic magnetostrictive materials, such as rare earth zinc crystals, offer high strains and high forces with minimally applied magnetic fields, making the material ideally suited for deformable optics applications. For cryogenic temperature applications, such as Next Generation Space Telescope (NGST), the use of superconducting magnets offer the possibility of a persistent mode of operation, i.e., the magnetostrictive material will maintain a strain field without power. High temperature superconductors (HTS) are attractive options if the temperature of operation is higher than 10 degrees Kelvin (K) and below 77 K. However, HTS wires have constraints that limit the minimum radius of winding, and even if good wires can be produced, the technology for joining superconducting wires does not exist. In this paper, the design and capabilities of a rare earth zinc magnetostrictive actuator using bulk HTS is described. Bulk superconductors can be fabricated in the sizes required with excellent superconducting properties. Equivalent permanent magnets, made with this inexpensive material, are persistent, do not require a persistent switch as in HTS wires, and can be made very small. These devices are charged using a technique which is similar to the one used for charging permanent magnets, e.g., by driving them into saturation. A small normal conducting coil can be used for charging or discharging. Very fast charging and discharging of HTS tubes, as short as 100 microseconds, has been demonstrated. Because of the magnetic field capability of the superconductor material, a very small amount of superconducting magnet material is needed to actuate the rare earth zinc. In this paper, several designs of actuators using YBCO and BSCCO 2212 superconducting materials are presented. Designs that include magnetic shielding to prevent interaction between adjacent actuators will also be described. Preliminary experimental results and comparison with theory for BSSCO 2212 with a

Research on the influence of driving harmonic on electromagnetic field and temperature field of permanent magnet synchronous motor

Directory of Open Access Journals (Sweden)

Qiu Hongbo

2017-06-01

Full Text Available At present, the drivers with different control methods are used in most of permanent magnet synchronous motors (PMSM. A current outputted by a driver contains a large number of harmonics that will cause the PMSM torque ripple, winding heating and rotor temperature rise too large and so on. In this paper, in order to determine the influence of the current harmonics on the motor performance, different harmonic currents were injected into the motor armature. Firstly, in order to study the influence of the current harmonic on the motor magnetic field, a novel decoupling method of the motor magnetic field was proposed. On this basis, the difference of harmonic content in an air gap magnetic field was studied, and the influence of a harmonic current on the air gap flux density was obtained. Secondly, by comparing the fluctuation of the motor torque in the fundamental and different harmonic currents, the influence of harmonic on a motor torque ripple was determined. Then, the influence of different current harmonics on the eddy current loss of the motor was compared and analyzed, and the influence of the drive harmonic on the eddy current loss was obtained. Finally, by using a finite element method (FEM, the motor temperature distribution with different harmonics was obtained.

Enhancement of structural and magnetic properties of M-type hexaferrite permanent magnet based on synthesis temperature

Science.gov (United States)

Anjum, Safia; Sehar, Fatima; Mustafa, Zeeshan; Awan, M. S.

2018-01-01

The main purpose of this research work is to develop the single domain magnetic particles of M-type barium hexaferrite (BaFe12O19) using oxide precursors employing conventional powder metallurgy technique. The phase formation and magnetic performance of the powders and magnets will be optimized by adjusting calcination and sintering temperatures. The synthesis of M-type barium hexaferrite was carried out in two sections. A series of four samples have been prepared by initial wet mixed powders calcined at different temperatures, i.e., 750, 850, 950 and 1050 °C. On the basis of structural analysis, the sample calcined at 950 °C has been selected and further divided into four parts to sintered them at 1100, 1150, 1200 and 1250 °C. The structural measurements depict the confirmation of M-type barium hexaferrite structure. SEM micrographs show the hexagonal-shaped grains. The abrupt decrease in coercivity for the sample sintered at 1250 °C has been seen which may be due to high sintering temperature, at which the particles have multi-domain properties.

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)

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.

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...

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.

Geometry optimization of five-phase permanent magnet synchronous motors using Bees algorithm

Directory of Open Access Journals (Sweden)

R Ilka

2015-12-01

Full Text Available Among all types of electrical motors, permanent magnet synchronous motors (PMSMs are reliable and efficient motors in industrial applications. Because of their superiority over other kinds of motors, they are replacing conventional electric motors. On the other hand, high-phase PMSMs are good candidates to be used in certain industrial and military projects such as electric vehicles, spacecrafts, naval systems and etc. In these cases, the motor has to be designed with minimum volume and high torque and efficiency. Design optimization can improve their features noticeably, thus reduce volume and enhance performance of motors. In this paper, a new method for optimum design of a five-phase surface-mounted permanent magnet synchronous motor is presented to achieve minimum permanent magnets (PMs volume with an increased torque and efficiency. Design optimization is performed in search for optimum dimensions of the motor and its permanent magnets using Bees Algorithm (BA. The design optimization results in a motor with great improvement regarding the original motor which is compared with two well-known evolutionary algorithms i.e. GA and PSO. Finally, finite element method simulation is utilized to validate the accuracy of the design.

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

Study of flow fractionation characteristics of magnetic chromatography utilizing high-temperature superconducting bulk magnet

Directory of Open Access Journals (Sweden)

Satoshi Fukui, Yoshihiro Shoji, Jun Ogawa, Tetsuo Oka, Mitsugi Yamaguchi, Takao Sato, Manabu Ooizumi, Hiroshi Imaizumi and Takeshi Ohara

2009-01-01

Full Text Available We present numerical simulation of separating magnetic particles with different magnetic susceptibilities by magnetic chromatography using a high-temperature superconducting bulk magnet. The transient transport is numerically simulated for two kinds of particles having different magnetic susceptibilities. The time evolutions were calculated for the particle concentration in the narrow channel of the spiral arrangement placed in the magnetic field. The field is produced by the highly magnetized high-temperature superconducting bulk magnet. The numerical results show the flow velocity difference of the particle transport corresponding to the difference in the magnetic susceptibility, as well as the possible separation of paramagnetic particles of 20 nm diameter.

Study of flow fractionation characteristics of magnetic chromatography utilizing high-temperature superconducting bulk magnet.

Science.gov (United States)

Fukui, Satoshi; Shoji, Yoshihiro; Ogawa, Jun; Oka, Tetsuo; Yamaguchi, Mitsugi; Sato, Takao; Ooizumi, Manabu; Imaizumi, Hiroshi; Ohara, Takeshi

2009-02-01

We present numerical simulation of separating magnetic particles with different magnetic susceptibilities by magnetic chromatography using a high-temperature superconducting bulk magnet. The transient transport is numerically simulated for two kinds of particles having different magnetic susceptibilities. The time evolutions were calculated for the particle concentration in the narrow channel of the spiral arrangement placed in the magnetic field. The field is produced by the highly magnetized high-temperature superconducting bulk magnet. The numerical results show the flow velocity difference of the particle transport corresponding to the difference in the magnetic susceptibility, as well as the possible separation of paramagnetic particles of 20 nm diameter.

An evaluation of alternative stator lamination materials for a high-speed, 1.5 MW, permanent magnet generator

NARCIS (Netherlands)

Paulides, J.J.H.; Jewell, G.W.; Howe, D.

2004-01-01

The influence of the choice of stator lamination material on the iron loss in a high speed, high power permanent magnet generator, which is interfaced to a DC link via a simple bridge rectifier, is investigated. The rating of the generator is representative of machines which would be employed in

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

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.)

Improvement of the rotational characteristics in the HTSC-permanent magnet hybrid bearing using ring shaped magnet

Energy Technology Data Exchange (ETDEWEB)

Emoto, Kozo; Sugiyama, Ryo; Takagi, Shogo; Ohashi, Shunsuke, E-mail: k145676@kansai-u.ac.jp

2013-11-15

Highlights: •We have developed the HTS-permanent magnet hybrid bearing system. •Three dimensional numerical analysis is undertaken to get the effective hybrid configuration. •Repulsive force and pinning force are combined effectively. •The hybrid system shows better levitation characteristics than the non-hybrid one. •In the mechanical resonance state, vibration of the rotor in the hybrid system is small. -- Abstract: We have developed the hybrid magnetic bearing using permanent magnets and the high-T{sub c} bulk superconductor (HTSC). Pinning force of the HTSC is used for the levitation and the guidance. Repulsive force of the permanent magnets is introduced to increase the load weight of the magnetic bearing. In this system, the stator side permanent magnet has the ring type structure so that both pinning force and repulsive force are used effectively. In this paper, influence of the hybrid system on dynamic characteristics of the rotor is studied. The rotor which is supported by the hybrid magnetic bearing is rotated. Then, vibration and the gradient angle of the rotor are measured until the rotor reaches to the end of the resonance state. Three dimensional numerical analysis of the flux which penetrates on the surface of the HTSC is undertaken. The relation between the dynamic characteristics and the flux is considered, and that of the hybrid system is compared with the non-hybrid one. In the hybrid system, the flux is changed by the influences of the stator side permanent magnet. Vibration and the gradient angle of the hybrid system are shown to be smaller than that of the non-hybrid one.

Improvement of the rotational characteristics in the HTSC-permanent magnet hybrid bearing using ring shaped magnet

International Nuclear Information System (INIS)

Emoto, Kozo; Sugiyama, Ryo; Takagi, Shogo; Ohashi, Shunsuke

2013-01-01

Highlights: •We have developed the HTS-permanent magnet hybrid bearing system. •Three dimensional numerical analysis is undertaken to get the effective hybrid configuration. •Repulsive force and pinning force are combined effectively. •The hybrid system shows better levitation characteristics than the non-hybrid one. •In the mechanical resonance state, vibration of the rotor in the hybrid system is small. -- Abstract: We have developed the hybrid magnetic bearing using permanent magnets and the high-T c bulk superconductor (HTSC). Pinning force of the HTSC is used for the levitation and the guidance. Repulsive force of the permanent magnets is introduced to increase the load weight of the magnetic bearing. In this system, the stator side permanent magnet has the ring type structure so that both pinning force and repulsive force are used effectively. In this paper, influence of the hybrid system on dynamic characteristics of the rotor is studied. The rotor which is supported by the hybrid magnetic bearing is rotated. Then, vibration and the gradient angle of the rotor are measured until the rotor reaches to the end of the resonance state. Three dimensional numerical analysis of the flux which penetrates on the surface of the HTSC is undertaken. The relation between the dynamic characteristics and the flux is considered, and that of the hybrid system is compared with the non-hybrid one. In the hybrid system, the flux is changed by the influences of the stator side permanent magnet. Vibration and the gradient angle of the hybrid system are shown to be smaller than that of the non-hybrid one

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

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

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.

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.

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.)

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)

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

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

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)

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.)

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.

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.

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.

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.

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)

High energy proton induced radiation damage of rare earth permanent magnet quadrupoles

Science.gov (United States)

Schanz, M.; Endres, M.; Löwe, K.; Lienig, T.; Deppert, O.; Lang, P. M.; Varentsov, D.; Hoffmann, D. H. H.; Gutfleisch, O.

2017-12-01

Permanent magnet quadrupoles (PMQs) are an alternative to common electromagnetic quadrupoles especially for fixed rigidity beam transport scenarios at particle accelerators. Using those magnets for experimental setups can result in certain scenarios, in which a PMQ itself may be exposed to a large amount of primary and secondary particles with a broad energy spectrum, interacting with the magnetic material and affecting its magnetic properties. One specific scenario is proton microscopy, where a proton beam traverses an object and a collimator in which a part of the beam is scattered and deflected into PMQs used as part of a diagnostic system. During the commissioning of the PRIOR (Proton Microscope for Facility for Antiproton and Ion Research) high energy proton microscope facility prototype at Gesellschaft für Schwerionenforschung in 2014, a significant reduction of the image quality was observed which was partially attributed to the demagnetization of the used PMQ lenses and the corresponding decrease of the field quality. In order to study this phenomenon, Monte Carlo simulations were carried out and spare units manufactured from the same magnetic material—single wedges and a fully assembled PMQ module—were deliberately irradiated by a 3.6 GeV intense proton beam. The performed investigations have shown that in proton radiography applications the above described scattering may result in a high irradiation dose in the PMQ magnets. This did not only decrease the overall magnetic strength of the PMQs but also caused a significant degradation of the field quality of an assembled PMQ module by increasing the parasitic multipole field harmonics which effectively makes PMQs impractical for proton radiography applications or similar scenarios.

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...

Design and development of permanent magnet based focusing lens for J-Band Klystron

Energy Technology Data Exchange (ETDEWEB)

Singh, Kumud; Itteera, Janvin; Ukarde, Priti; Malhotra, Sanjay; Taly, Y.K., E-mail: kumuds@barc.gov.in [Control Instrumentation Division, Bhabha Atomic Research Centre, Mumbai (India); Bandyopadhay, Ayan; Meena, Rakesh; Rawat, Vikram; Joshi, L.M [Microwave Tubes Division, Central Electronics Engineering Research Institute, Pilani (India)

2014-07-01

Applying permanent magnet technology to beam focusing in klystrons can reduce their power consumption and increase their reliability of operation. Electromagnetic design of the beam focusing elements, for high frequency travelling wave tubes, is very critical. The magnitude and profile of the magnetic field need to match the optics requirement from beam dynamics studies. The rise of the field from cathode gun region to the uniform field region (RF section) is important as the desired transition from zero to peak axial field must occur over a short axial distance. Confined flow regime is an optimum choice to minimize beam scalloping but demands an axial magnetic field greater than 2 - 3 times the Brillouin flow field. This necessitates optimization in the magnet design achieve high magnetic field within given spatial constraints. Electromagnetic design and simulations were done using 3D Finite element method (FEM) analysis software. A permanent magnet based focusing lens for a miniature J-Band klystron has been designed and developed at Control Instrumentation Division, BARC. This paper presents the design, simulation studies, beam transmission and RF tests results for J Band klystron with permanent magnet focusing lens. (author)

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

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

Sensorless interior permanent magnet synchronous motor control with rotational inertia adjustment

Directory of Open Access Journals (Sweden)

Yongle Mao

2016-12-01

Full Text Available Mechanical model is generally required in high dynamic sensorless motor control schemes for zero phase lag estimation of rotor position and speed. However, the rotational inertia uncertainty will cause dynamic estimation errors, eventually resulting in performance deterioration of the sensorless control system. Therefore, this article proposes a high dynamic performance sensorless control strategy with online adjustment of the rotational inertia. Based on a synthetic back electromotive force model, the voltage equation of interior permanent magnet synchronous motor is transformed to that of an equivalent non-salient permanent magnet synchronous motor. Then, an extended nonlinear observer is designed for interior permanent magnet synchronous motor in the stator-fixed coordinate frame, with rotor position, speed and load torque simultaneously estimated. The effect of inaccurate rotational inertia on the estimation of rotor position and speed is investigated, and a novel rotational inertia adjustment approach that employs the gradient descent algorithm is proposed to suppress the dynamic estimation errors. The effectiveness of the proposed control strategy is demonstrated by experimental tests.

Determination of the High Frequency Inductance Profile of Surface Mounted Permanent Magnet Synchronous Motors

DEFF Research Database (Denmark)

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

2008-01-01

) synchronous motors. This paper presents an AC+DC measurement method for determination of the d-axis and q-axis high frequency inductance profiles of SMPM synchronous motors. This method uses DC currents to set a desired magnetic working point on the motor laminations, and then superimpose balanced small AC......Accurate knowledge of the high frequency inductance profile plays an important role in many designs of sensorless controllers for Surface inductance. A special algorithm is used to decouple the cross-coupling effects between the d-axis and the q-axis, which allows Mounted Permanent Magnet (SMPM...... signals to measure the incremental a separate determination of the d, q inductance profiles as functions of the d, q currents. Experimental results on a commercial SMPM motor using the proposed method are presented in this paper....

A 3D Dynamic Lumped Parameter Thermal Network of Air-Cooled YASA Axial Flux Permanent Magnet Synchronous Machine

Directory of Open Access Journals (Sweden)

Abdalla Hussein Mohamed

2018-03-01

Full Text Available To find the temperature rise for high power density yokeless and segmented armature (YASA axial flux permanent magnet synchronous (AFPMSM machines quickly and accurately, a 3D lumped parameter thermal model is developed and validated experimentally and by finite element (FE simulations on a 4 kW YASA machine. Additionally, to get insight in the thermal transient response of the machine, the model accounts for the thermal capacitance of different machine components. The model considers the stator, bearing, and windage losses, as well as eddy current losses in the magnets on the rotors. The new contribution of this work is that the thermal model takes cooling via air channels between the magnets on the rotor discs into account. The model is parametrized with respect to the permanent magnet (PM angle ratio, the PM thickness ratio, the air gap length, and the rotor speed. The effect of the channels is incorporated via convection equations based on many computational fluid dynamics (CFD computations. The model accuracy is validated at different values of parameters by FE simulations in both transient and steady state. The model takes less than 1 s to solve for the temperature distribution.

A conceptual design of high-temperature superconducting isochronous cyclotron magnet

International Nuclear Information System (INIS)

Jiao, F.; Tang, Y.; Li, J.; Ren, L.; Shi, J.

2011-01-01

A design of High-temperature superconducting (HTS) isochronous cyclotron magnet is proposed. The maximum magnetic field of cyclotron main magnet reaches 3 T. Laying the HTS coil aboard the magnetic pole will raise the availability of the magnetic Field. Super-iron structure can provide a high uniformity and high gradient magnetic field. Super-iron structure can raise the availability of the HTS materials. Along with the development of High-temperature superconducting (HTS) materials, the technology of HTS magnet is becoming increasingly important in the Cyclotron, which catches growing numbers of scholars' attentions. Based on the analysis of the problems met in the process of marrying superconducting materials with ferromagnetic materials, this article proposes a design of HTS isochronous cyclotron magnet. The process of optimization of magnet and the methods of realizing target parameters are introduced after taking finite element software as analyzing tools.

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.

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.

High-energy electron irradiation of NdFeB permanent magnets: Dependence of radiation damage on the electron energy

Energy Technology Data Exchange (ETDEWEB)

Bizen, Teruhiko [JASRI SPring-8, 1-1-1 Kouto Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan)]. E-mail: bizen@spring8.or.jp; Asano, Yoshihiro [JASRI SPring-8, 1-1-1 Kouto Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan); RIKEN SPring-8 Center, 1-1-1 Kouto Sayo-cho, Sayo-gun, Hyogo 679-5148 (Japan); Marechal, Xavier-Marie [JASRI SPring-8, 1-1-1 Kouto Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan); Seike, Takamitsu [JASRI SPring-8, 1-1-1 Kouto Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan); Aoki, Tsuyoshi [JASRI SPring-8, 1-1-1 Kouto Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan); Fukami, Kenji [JASRI SPring-8, 1-1-1 Kouto Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan); Hosoda, Naoyasu [JASRI SPring-8, 1-1-1 Kouto Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan); Yonehara, Hiroto [JASRI SPring-8, 1-1-1 Kouto Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan); Takagi, Tetsuya [JASRI SPring-8, 1-1-1 Kouto Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan); Hara, Toru [RIKEN SPring-8 Center, 1-1-1 Kouto Sayo-cho, Sayo-gun, Hyogo 679-5148 (Japan); Tanaka, Takashi [RIKEN SPring-8 Center, 1-1-1 Kouto Sayo-cho, Sayo-gun, Hyogo 679-5148 (Japan); Kitamura, Hideo [RIKEN SPring-8 Center, 1-1-1 Kouto Sayo-cho, Sayo-gun, Hyogo 679-5148 (Japan)

2007-05-11

High-energy electron-beam bombardment of Nd{sub 2}Fe{sub 14}B-type permanent magnets induces radiation damage characterized by a drop in the magnetic field. Experiments carried out at the SPring-8 booster synchrotron, with 4, 6, and 8 GeV electrons, show that the drop in magnetic field is energy dependent. Electromagnetic shower simulations suggest that most of the radiation damage happens in a small region around the irradiation axis, and that the contribution of neutrons with large scattering angles or with low energies to the magnetic field change is small.

High-energy electron irradiation of NdFeB permanent magnets: Dependence of radiation damage on the electron energy

International Nuclear Information System (INIS)

Bizen, Teruhiko; Asano, Yoshihiro; Marechal, Xavier-Marie; Seike, Takamitsu; Aoki, Tsuyoshi; Fukami, Kenji; Hosoda, Naoyasu; Yonehara, Hiroto; Takagi, Tetsuya; Hara, Toru; Tanaka, Takashi; Kitamura, Hideo

2007-01-01

High-energy electron-beam bombardment of Nd 2 Fe 14 B-type permanent magnets induces radiation damage characterized by a drop in the magnetic field. Experiments carried out at the SPring-8 booster synchrotron, with 4, 6, and 8 GeV electrons, show that the drop in magnetic field is energy dependent. Electromagnetic shower simulations suggest that most of the radiation damage happens in a small region around the irradiation axis, and that the contribution of neutrons with large scattering angles or with low energies to the magnetic field change is small

Radiation hardness of permanent magnets of NdFeB in high energy neutron fields

International Nuclear Information System (INIS)

Shchegolev, V.Yu.

2003-01-01

Magnetic properties of NdFeB permanent magnet samples were measured before and after irradiation with conditions similar to conditions of DRIBs (phase 1) (FLNR, JINR) facility. Demagnetization of the samples after 8-day irradiation was found to be in the range of 17 to 87 %. Estimation of magnet 'life time' was made in the case of setting up these magnets on ECR ion source of DRIBs (phase 1) facility. Possible reasons of considerable demagnetization of the magnets are discussed. (author)

Radiation Hardness of Permanent Magnets of NdFeB in High Energy Neutrons Field

CERN Document Server

Schegolev, V Yu

2003-01-01

Magnetic properties of NdFeB permanent magnet samples were measured before and after irradiation with conditions similar to conditions of DRIBs (phase 1) (FLNR, JINR) facility. Demagnetization of the samples after 8-day irradiation was found to be in the range of 17 to 87 \\%. Estimation of magnet "life tim" was made in the case of setting up these magnets on ECR ion source of DRIBs (phase 1) facility. Possible reasons of considerable demagnetization of the magnets are discussed.

Radiation hardness of permanent magnets of NdFeB in high energy neutron fields

CERN Document Server

Shchegolev, V Y

2003-01-01

Magnetic properties of NdFeB permanent magnet samples were measured before and after irradiation with conditions similar to conditions of DRIBs (phase 1) (FLNR, JINR) facility. Demagnetization of the samples after 8-day irradiation was found to be in the range of 17 to 87 %. Estimation of magnet 'life time' was made in the case of setting up these magnets on ECR ion source of DRIBs (phase 1) facility. Possible reasons of considerable demagnetization of the magnets are discussed.

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)

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.)

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…

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...

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.

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.

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.

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.

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.

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

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

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

Armature reaction of permanent magnet-excited small dc motors with shell type magnets and possibilities of power increase

Energy Technology Data Exchange (ETDEWEB)

Gutt, H J; Tran, Q N

1983-07-01

Permanent magnet-excited small dc motors allow an increase of power up to 30% compared with present permanent excited motors. The calculation of immediate irreversible demagnetization of the air-gap situated shell type magnets is necessary for a good motor design. Numerical calculated field line plots show the critical zones of the irreversible demagnetization at high armature reaction and refer how to avoid the flux loss and to increase the motor power.