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Sample records for active magnetic bearings

  1. Active Magnetic BearingsMagnetic Forces

    Kjølhede, Klaus

    2006-01-01

    Parameter identification procedures and model validation are major steps towards intelligent machines supported by active magnetic bearings (AMB). The ability of measuring the electromagnetic bearing forces, or deriving them from measuring the magnetic flux, strongly contributes to the model...... the work is the characterization of magnetic forces by using two experimental different experimental approaches. Such approaches are investigated and described in details. A special test rig is designed where the 4 poles - AMB is able to generate forces up to 1900 N. The high precision...... characterization of the magnetic forces are led by using different experimental tests: (I) by using hall sensors mounted directly on the poles (precise measurements of the magnetic flux) and by an auxiliary system, composed of strain gages and flexible beams attached to the rotor; (II) by measuring the input...

  2. Active Magnetic BearingsMagnetic Forces

    Kjølhede, Klaus

    2006-01-01

    the work is the characterization of magnetic forces by using two experimental different experimental approaches. Such approaches are investigated and described in details. A special test rig is designed where the 4 poles - AMB is able to generate forces up to 1900 N. The high precision......Parameter identification procedures and model validation are major steps towards intelligent machines supported by active magnetic bearings (AMB). The ability of measuring the electromagnetic bearing forces, or deriving them from measuring the magnetic flux, strongly contributes to the model...... characterization of the magnetic forces are led by using different experimental tests: (I) by using hall sensors mounted directly on the poles (precise measurements of the magnetic flux) and by an auxiliary system, composed of strain gages and flexible beams attached to the rotor; (II) by measuring the input...

  3. Active magnetic bearing-supported rotor with misaligned cageless backup bearings: A dropdown event simulation model

    Halminen, Oskari; Kärkkäinen, Antti; Sopanen, Jussi; Mikkola, Aki

    2015-01-01

    Active magnetic bearings (AMB) offer considerable benefits compared to regular mechanical bearings. On the other hand, they require backup bearings to avoid damage resulting from a failure in the component itself, or in the power or control system. During a rotor-bearing contact event - when the magnetic field has disappeared and the rotor drops on the backup bearings - the structure of the backup bearings has an impact on the dynamic actions of the rotor. In this paper, the dynamics of an active magnetic bearing-supported rotor during contact with backup bearings is studied with a simulation model. Modeling of the backup bearings is done using a comprehensive cageless ball bearing model. The elasticity of the rotor is described using the finite element method (FEM) and the degrees of freedom (DOF) of the system are reduced using component mode synthesis. Verification of the misaligned cageless backup bearings model is done by comparing the simulation results against the measurement results. The verified model with misaligned cageless backup bearings is found to correspond to the features of a real system.

  4. Active magnetic bearings used as exciters for rolling element bearing outer race defect diagnosis.

    Xu, Yuanping; Di, Long; Zhou, Jin; Jin, Chaowu; Guo, Qintao

    2016-03-01

    The active health monitoring of rotordynamic systems in the presence of bearing outer race defect is considered in this paper. The shaft is assumed to be supported by conventional mechanical bearings and an active magnetic bearing (AMB) is used in the mid of the shaft location as an exciter to apply electromagnetic force to the system. We investigate a nonlinear bearing-pedestal system model with the outer race defect under the electromagnetic force. The nonlinear differential equations are integrated using the fourth-order Runge-Kutta algorithm. The simulation and experimental results show that the characteristic signal of outer race incipient defect is significantly amplified under the electromagnetic force through the AMBs, which is helpful to improve the diagnosis accuracy of rolling element bearing׳s incipient outer race defect. PMID:26803551

  5. Roles of superconducting magnetic bearings and active magnetic bearings in attitude control and energy storage flywheel

    Compared with conventional energy storage flywheel, the rotor of attitude control and energy storage flywheel (ACESF) used in space not only has high speed, but also is required to have precise and stable direction. For the presented superconducting magnetic bearing (SMB) and active magnetic bearing (AMB) suspended ACESF, the rotor model including gyroscopic couples is established originally by taking the properties of SMB and AMB into account, the forces of SMB and AMB are simplified by linearization within their own neighbors of equilibrium points. For the high-speed rigid discal rotor with large inertia, the negative effect of gyroscopic effect of rotor is prominent, the radial translation and tilting movement of rotor suspended by only SMB, SMB with equivalent PMB, or SMB together with PD controlled AMB are researched individually. These analysis results proved originally that SMB together with AMB can make the rotor be stable and make the radial amplitude of the vibration of rotor be small while the translation of rotor suspended by only SMB or SMB and PM is not stable and the amplitude of this vibration is large. For the stability of the high-speed rotor in superconducting ACESF, the AMB can suppress the nutation and precession of rotor effectively by cross-feedback control based on the separated PD type control or by other modern control methods.

  6. Condition monitoring of active magnetic bearing systems / Rupert Gouws

    Gouws, Rupert

    2007-01-01

    In this thesis, the author contextualises condition monitoring of active magnetic bearing (AMB) systems and proposes the real-time condition monitoring of AMB systems. Three real-time fault detection, diagnosis, correction and identification schemes for vibration forces on the rotor of a rotational AMB system are proposed. Two AMB systems were used to conduct this research. The one was a fully suspended 250 kW water cooling AMB pump from which historical fault data was obtained and the oth...

  7. Fault Diagnosis in a Centrifugal Pump Using Active Magnetic Bearings

    Nordmann Rainer; Aenis Martin

    2004-01-01

    The number of rotors running in active magnetic bearings (AMBs) has increased over the last few years. These systems offer a great variety of advantages compared to conventional systems. The aim of this article is to use the AMBs together with a developed built-in software for identification, fault detection, and diagnosis in a centrifugal pump. A single-stage pump representing the turbomachines is investigated. During full operation of the pump, the AMBs are used as actuators to generate def...

  8. The development of an axial active magnetic bearing / R. Gouws

    Gouws, Rupert

    2004-01-01

    In this dissertation, the author presents the operation and development of active magnetic bearings (AMBs) , with specific focus on axial M s . The project objective is the development of an axial AMB system. The electromagnetic design, inductive sensor design, dSpace controller model design and actuating amplifier design are aspects discussed in this dissertation. The physical model constitutes two electromagnets positioned above and beneath a 2 kg steel disc with an air gap o...

  9. Experimental Contribution to High Precision Characterization of Magnetic Forces in Active Magnetic Bearings

    Kjølhede, Klaus; Santos, Ilmar

    2006-01-01

    Parameter identification procedures and model validation are major steps towards intelligent machines supported by active magnetic bearings (AMB). The ability of measuring the electromagnetic bearing forces, or deriving them from measuring the magnetic flux, strongly contributes to the model vali...... with respect to the instantaneous measured force obtained from the strain gauges signals)...... magnetic forces is conducted using different experimental tests: (a) by using hall sensors mounted directly on the poles (precise measurements of the magnetic flux) and by an auxiliary system, composed of strain gages and flexible beams attached to the rotor, (b) by measuring the input current and bearing...

  10. Experimental Contribution to High Precision Characterization of Magnetic Forces in Active Magnetic Bearings

    Kjølhede, Klaus; Santos, Ilmar

    Parameter identification procedures and model validation are major steps towards intelligent machines supported by active magnetic bearings (AMB). The ability of measuring the electromagnetic bearing forces, or deriving them from measuring the magnetic flux, strongly contributes to the model vali...... with respect to the instantaneous measured force obtained from the strain gauges signals)...... magnetic forces is conducted using different experimental tests: (a) by using hall sensors mounted directly on the poles (precise measurements of the magnetic flux) and by an auxiliary system, composed of strain gages and flexible beams attached to the rotor, (b) by measuring the input current and bearing...

  11. THE EXPERIMENTAL TESTING OF AN ACTIVE MAGNETIC BEARING/ROTOR SYSTEM UNDERGOING BASE EXCITATION

    Clements, Joshua Ryan

    2000-01-01

    Active Magnetic Bearings (AMB) are a relatively recent innovation in bearing technology. Unlike conventional bearings, which rely on mechanical forces originating from fluid films or physical contact to support bearing loads, AMB systems utilize magnetic fields to levitate and support a shaft in an air-gap within the bearing stator. This design has many benefits over conventional bearings. The potential capabilities that AMB systems offer are allowing this new technology to be considered f...

  12. R+D works for the further development of high temperature reactors. (1) Captive bearing experiments for active magnetic bearings. (2) Captive bearing test for HTR blowers

    When using active magnetic bearings as blower shaft bearings, blower motors and bearings must be protected against mechanical damage in case of faults (example: total electrical supply failure due to the supply cables breaking). So-called captive bearings are provided, in order to be able to shut the blowers down safely in such faults. These captive bearings are roller bearings which are additionally fitted in the area of the blower shaft bearings, to prevent mechanical contact between the blower rotor and stator. As there was little experience available for the given boundary conditions, such as - speed, - acceleration, - bearing load, - bearing dimensions, - ambient conditions, appropriate development and tests had to be carried out. It was important to determine suitable captive bearings and the necessary ambient conditions, which will make it possible to support the failures of the magnetic bearings to be expected in 40 years' operation of the reactor without damage and to meet the requirements of the captive bearings. (orig./GL)

  13. Developments in the field of active magnetic bearings at EDF

    The studies carried out by EDF concerning the evaluation of the active magnetic bearing technology for their possible application to rotating machinery in electrical plants, and especially the 900 MW ''CP2'' turbogenerators which appear to have very little damping and vibrate noticeably during transients. Using a 4 tons test bench, the good quality of simulation applied to both permanent and transient conditions have been verified. Then, using a 10 tons test bench, the dimensioning concerns of the CP2 application were more precisely evaluated. It has been especially demonstrated that the accessible levels of force and damping were compatible with the application constraints. In a final 30 tons project, some innovative technological components have been used and the benefits from an optimization of the design of the magnetic parameters were determined. Specifications for a full-scale implementation have been therefore defined to enable the manufacturer to make a commercial offer. After a disappointing analysis of the offer, CP2 computations and studies were stopped but subsidiary studies were conducted: estimation of the damage risk under alternative bending of the CP2 rotors during their lifetime, prospective analysis of other possible applications of active magnetic bearings in power plants, development of a new vibratory test method through electromagnetic excitation. 5 figs., 6 refs

  14. Failure Mode and Effect Analysis of Active Magnetic Bearings

    K.P. Lijesh

    2016-03-01

    Full Text Available In the present research work Failure Mode and Effect Analysis (FMEA of an Active Magnetic Bearing (AMB has been presented. Various possible failures modes of AMBs and the corresponding effects of those failures on performance of AMBs have been identified. The identified failure modes of AMBs will facilitate designer to incorporate necessary design features that would prevent the occurrence of the failure. The severity, occurrence and detection of the failures modes are determined based on a rating scale of 1 to 5 to quantify the Risk Priority Number (RPN of the failure modes. The methods to eliminate or reduce the high-risk-failure modes are proposed.

  15. Active magnetic bearings: As applied to centrifugal pumps

    Nelik, Lev; Cooper, Paul; Jones, Graham; Galecki, Dennis; Pinckney, Frank; Kirk, Gordon

    1992-01-01

    Application of magnetic bearings to boiler feed pumps presents various attractive features, such as longer bearing life, lower maintenance costs, and improved operability through control of the rotordynamics. Magnetic bearings were fitted to an eight-stage, 600 hp boiler feed pump, which generates 2600 ft of heat at 680 gpm and 3560 rpm. In addition to the varied and severe operating environment in steady state operation of this pump in a power plant, it is also subjected to transient loads during frequent starts and stops. These loads can now be measured by the in-built instrumentation of the magnetic bearings. Following site installation, a follow-up bearing tune-up was performed, and pump transient response testing was conducted. The bearing response was completely satisfactory, ensuring trouble-free pump operation even in the range of reduced load. The experience gained so far through design and testing proves feasibility of magnetic bearings for boiler feed pumps, which sets the stage for application of even higher energy centrifugal pumps equipped with magnetic bearings.

  16. The thermodynamic properties of a new type catcher bearing used in active magnetic bearings system

    Normally a rotor levitated by active magnetic bearings (AMBs) system would rotate without contacting with any stator component, but the possibility still remains that the supporting force might lose temporarily or permanently, thus requiring the Catcher bearings (CBs) to provide backup protection in case of the failure of AMBs. A new type CB with two separate rolling element bearing series could have the speed distribution between the inner race and intermediate race according to certain ratio, in which the speed of each roller element bearing decreases with the limit speed of the whole CB increasing, offering high capability to sustain its initial rotation speed. Based on the theory of heat transfer, tribology, and rotor dynamics, this paper analyzes the thermal structure of double-decker catcher bearing (DDCB) and single-decker catcher bearing (SDCB), respectively. Through this structure, the thermal resistances and equations of heat transfer can be obtained. Then we calculate the friction heat and temperature distribution in the various CBs upon rotor's dropping on SDCB or DDCB, followed by the discussion on the CBs temperature rise's effects on lubrication conditions and rotor dynamics parameters. Finally various experiments are carried out to measure the temperature rise of different CBs. The results obtained validate the theoretical analysis and also provide main methods to reduce heat generation. Using DDCB is proved to be effective to reduce the temperature rise. - Highlights: • The DDCB is a more suitable catcher bearing for AMBs. • Compared to SDCB, using DDCB, the temperature rise can decrease in the same states. • A lower viscosity of lubricant may induce a lower temperature rise. • The inner raceway temperature of the first layer bearing is the highest. • Reducing the unbalance mass of the rotor is a method to decrease the temperature rise

  17. Experimental Contribution to High-Precision Characterization of Magnetic Forces in Active Magnetic Bearings

    Kjølhede, Klaus; Santos, Ilmar

    2007-01-01

    Parameter identification procedures and model validation are major steps toward intelligent machines supported by active magnetic bearings (AMB). The ability of measuring the electromagnetic bearing forces, or deriving them from measuring the magnetic flux, strongly contributes to the model valid...... normalized with respect to the instantaneous measured force obtained from the strain gauges signals)....... the magnetic forces is conducted using different experimental tests: (i) by using hall sensors mounted directly on the poles (precise measurements of the magnetic flux) and by an auxiliary system, composed of strain gages and flexible beams attached to the rotor (ii) by measuring the input current and...

  18. Optimization of active magnetic bearings for automotive flywheel energy storage systems based on soft magnetic materials

    Wegleiter H.

    2013-01-01

    Full Text Available For active magnetically suspended rotors in mobile flywheel energy storage systems the lowest possible weight, smallest size and a low price is required. Since the flywheel is operated in vacuum and very little heat can be dissipated from the rotor, the bearing’s magnetic losses have to be as minimal as well. This paper compares the design and optimization of homopolar radial active magnetic bearings with 3 different types of laminated steel. The first type is a standard transformer steel, the second one is high flux cobalt steel and the third one is high flux cobalt steel with high tensile strength.

  19. Control of Active Axial Magnetic Bearings for Flywheel-based Energy Storage System

    Morís Gómez, Juan

    2014-01-01

    This thesis deals with the design and implementation of the control system for a Flywheel-based Energy Storage System (FESS) with active magnetic bearings. The thesis focuses on the construction of realistic model of the system according to experimental tests. The simulation model will be used to control the thrust magnetic bearings in order to withstand the flywheel in levitation.

  20. TRANSIENT TEMPERATURE FIELD IN ACTIVE THRUST MAGNETIC BEARING

    Sun Shouqun; Geng Haipeng; Guo Keqian

    2005-01-01

    A transient temperature field model in a thrust magnetic bearing is built in which the heat resources come mainly from the eddy-current loss of solid cores and the copper loss of coils. The transient temperature field, system temperature rise and the thermo-equilibrium state during the rotor starting-up are calculated considering only the copper loss and the eddy-current loss. The numerical results indicate that the temperatures in coils and in magnets rise rapidly, their thermo-equilibrium states are formed within a short time. The temperatures in a thrust-disk and in a rotor rise slowly, their thermo-equilibrium states are formed after a long period time. The temperatures of the thrust-disk and the rotor are far higher than the temperatures of coils and/or magnets after the thermo-equilibrium state has come into being.

  1. Passive magnetic bearing configurations

    Post, Richard F.

    2011-01-25

    A journal bearing provides vertical and radial stability to a rotor of a passive magnetic bearing system when the rotor is not rotating and when it is rotating. In the passive magnetic bearing system, the rotor has a vertical axis of rotation. Without the journal bearing, the rotor is vertically and radially unstable when stationary, and is vertically stable and radially unstable when rotating.

  2. Control of Surge in Centrifugal Compressors by Active Magnetic Bearings Theory and Implementation

    Yoon, Se Young; Allaire, Paul E

    2013-01-01

    Control of Surge in Centrifugal Compressors by Active Magnetic Bearings sets out the fundamentals of integrating the active magnetic bearing (AMB) rotor suspension technology in compressor systems, and describes how this relatively new bearing technology can be employed in the active control of compressor surge. The authors provide a self-contained and comprehensive review of rotordynamics and the fundamentals of the AMB technology. The active stabilization of compressor surge employing AMBs in a machine is fully explored, from the modeling of the instability and the design of feedback controllers, to the implementation and experimental testing of the control algorithms in a specially-constructed, industrial-size centrifugal compression system. The results of these tests demonstrate the great potential of the new surge control method developed in this text. This book will be useful for engineers in industries that involve turbocompressors and magnetic bearings, as well as for researchers and graduate students...

  3. Active Magnetic Bearings used as an Actuator for Rotor Health Monitoring in Conjunction with Conventional Support Bearings

    Bash, Travis Joel

    2005-01-01

    This thesis describes the test rig and results from a project expanding the field of rotor health monitoring by using Active Magnetic Bearings (AMBs) as actuators for applying a variety of known force inputs to a spinning. Similar to modal analysis and other nondestructive evaluation (NDE) techniques which apply input signals to static structures in order to monitor responses; this approach allows for the measurement of both input and output response in a rotating system for evaluation. How...

  4. Design and implement for control system of active magnetic bearings based on DSP

    Cao, Jie; Cao, Lihong

    2005-12-01

    Magnetic-bearings, which support shafts with magnetic levitation rather than mechanical contact, have been in industrial use for decades. Recent technological developments, especially in digital processing and control, have made magnetic bearings a more-robust and cost-effective design solution than ever. The dynamic characteristic of electromagnetic bearing depends upon adopted controller; the active control can makes the electromagnetic bearings to realize complex control and special control. With the development of signal processing technology and modern control theory, the main parts of the control system are the digital signal-processing (DSP) electronics, a power supply, and amplifiers. An Active Magnetic Bearing (AMB) controller is mainly discussed in the paper, which is to be solved to realize this flexible control by hardware design based on DSP using TMS320C32 processor. It is proved by experiment that this kind of controller can optimize for this system, improve its stability and also have a very important referential value on the further study of AMB system.

  5. Magnetic bearing momentum wheels with magnetic gimballing capability for 3-axis active attitude control and energy storage

    Sindlinger, R. S.

    1977-01-01

    Magnetic bearings used for the suspension of momentum wheels provide conclusive advantages: the low friction torques and the absence of abrasion allow the realization of lightweight high speed wheels with high angular momentum and energy storage capacity and virtually unlimited lifetime. The use of actively controlled bearings provides a magnetic gimballing capability by applying the external signals to the two servo loops controlling the rotational degrees of freedom. Thus, an attitude control system can be realized by using only one rotating mass for 3-axis active satellite stabilization.

  6. Active control of surge in centrifugal compressors using magnetic thrust bearing actuation

    Sanadgol, Dorsa

    This research presents a new method for active surge control in centrifugal compressors with unshrouded impellers using a magnetic thrust bearing to modulate the impeller tip clearance. Magnetic bearings offer the potential for active control of flow instabilities. This capability is highly dependent on the sensitivity of the compressor characteristics to blade tip clearance. If the position of the shaft can be actuated with sufficient authority and speed, the induced pressure modulation makes control of surge promising. The active nature of the magnetic bearing system makes the real-time static and dynamic positioning of the rotor and therefore modulation of the impeller tip clearance possible. A theoretical model is first established that describes the sensitivity of the centrifugal compressor characteristic curve to tip clearance variations induced by axial motion of the rotor. Results from simulation of the nonlinear model for a single stage high-speed centrifugal compressor show that using the proposed control method, mass flow and pressure oscillations associated with compressor surge are quickly suppressed with acceptable tip clearance excursions, typically less than 20% of the available clearance. It is shown that it is possible to produce adequate axial excursions in the clearance between the impeller blades and the adjacent stationary shroud using a magnetic thrust bearing with practical levels of drive voltage. This surge control method would allow centrifugal compressors to reliably and safely operate with a wider range than is currently done in the field. The principal advantage of the proposed approach over conventional surge control methods lies in that, in machines already equipped with magnetic bearing, the method can potentially be implemented by simply modifying controller software. This dispenses with the need to introduce additional hardware, permitting adaptation of existing machinery at virtually no cost. In addition, since the controller is

  7. Computer aided design of digital controller for radial active magnetic bearings

    Cai, Zhong; Shen, Zupei; Zhang, Zuming; Zhao, Hongbin

    1992-01-01

    A five degree of freedom Active Magnetic Bearing (AMB) system is developed which is controlled by digital controllers. The model of the radial AMB system is linearized and the state equation is derived. Based on the state variables feedback theory, digital controllers are designed. The performance of the controllers are evaluated according to experimental results. The Computer Aided Design (CAD) method is used to design controllers for magnetic bearings. The controllers are implemented with a digital signal processing (DSP) system. The control algorithms are realized with real-time programs. It is very easy to change the controller by changing or modifying the programs. In order to identify the dynamic parameters of the controlled magnetic system, a special experiment was carried out. Also, the online Recursive Least Squares (RLS) parameter identification method is studied. It can be realized with the digital controllers. Online parameter identification is essential for the realization of an adaptive controller.

  8. Modeling and flat control law for a fine pointing system based on semi active magnetic bearings

    Mahout, Vincent; Prats Menéndez, Xavier; Mignot, Jean

    2002-01-01

    In this paper aspects of non linear systems and flat control are studied for a specific application of a satellite fine pointing breadboard based on semi active magnetic bearings actuators. Authors propose a complete 6 degrees of freedom mechanical model which describes the system dynamics. A completely non linear and unstable system is obtained leading to implement non linear control laws. A combination of flat control, which ensures trajectory tracking and path plann...

  9. Impact of frequency switching on the efficiency of a fully suspended active magnetic bearing system

    Gouws, Rupert

    2012-01-01

    Due to the rising energy (and electricity) cost it is essential that an active magnetic bearing (AMB) system is operated as efficiently as possible. Frequency switching caused by an external source can cause an AMB system to operate at a higher than expected energy level and lower than expected efficiency. The purpose of this paper is therefore to investigate the impact of frequency switching (caused by an external source) on the efficiency of a fully suspended AMB system. The shaft of the fu...

  10. A Self-Sensing Active Magnetic Bearing Based on a Direct Current Measurement Approach

    Du Rand, Carel P.; George van Schoor; Niemann, Andries C.

    2013-01-01

    Active magnetic bearings (AMBs) have become a key technology in various industrial applications. Self-sensing AMBs provide an integrated sensorless solution for position estimation, consolidating the sensing and actuating functions into a single electromagnetic transducer. The approach aims to reduce possible hardware failure points, production costs, and system complexity. Despite these advantages, self-sensing methods must address various technical challenges to maximize the performance the...

  11. Adaptive control of an active magnetic bearing flywheel system using neural networks / Angelique Combrinck

    Combrinck, Angelique

    2010-01-01

    The School of Electrical, Electronic and Computer Engineering at the North-West University in Potchefstroom has established an active magnetic bearing (AMB) research group called McTronX. This group provides extensive knowledge and experience in the theory and application of AMBs. By making use of the expertise contained within McTronX and the rest of the control engineering community, an adaptive controller for an AMB flywheel system is implemented. The adaptive controller is ...

  12. Magnetostatic analysis of a rotor system supported by radial active magnetic bearings

    Ferfecki P.

    2009-01-01

    The development and the design of a radial active magnetic bearing (AMB) reflects a complex process of the multidisciplinary rotor dynamics, electromagnetism and automatic control analysis. Modelling is performed by application of the physical laws from different areas, e.g. Newton's laws of motion and Maxwell's equations. The new approach in the numerical modelling of radial AMB and design methodology allowing automatic generation of primary dimensions of the radial AMB is proposed. Instead ...

  13. Test and Theory of Electrodynamic Bearings Coupled to Active Magnetic Dampers

    Tonoli, Andrea; Girardello Detoni, Joaquim; Impinna, Fabrizio; Amati, Nicola

    2014-01-01

    Electrodynamic bearings (EDBs) are passive magnetic bearings that exploit the interaction between eddy currents developed in a rotating conductor and a static magnetic field to generate forces. Similar to other types of magnetic suspensions, EDBs provide contactless support, thus avoiding problems with lubrication, friction and wear. Electrodynamic bearings have also drawbacks such as the difficulty in insuring a stable levitation in a wide speed range. The paper presents a solution where the...

  14. Identifying parameters in active magnetic bearing system using LFT formulation and Youla factorization

    Lauridsen, Jonas; Sekunda, André Krabdrup; Santos, Ilmar;

    2015-01-01

    In this paper, a method for identifying uncertain parameters in a rotordynamic system composed of a flexible rotating shaft, rigid discs and two radial active magnetic bearings is presented. Shaft and disc dynamics are mathematically described using a Finite Element (FE) model while magnetic...... of the system matrix A of the full FE model while it is represented as several elements spread over multiple rows and columns of the system matrix of the reduced model. The parametric uncertainty, for both the full and reduced FE model, is represented using Linear Fractional Transformation (LFT). In...

  15. RESEARCH ON CONTROL OF FLYWHEEL SUSPENDED BY ACTIVE MAGNETIC BEARING SYSTEM WITH SIGNIFICANT GYROSCOPIC EFFECTS

    Zhang Kai; Zhao Lei; Zhao Hongbin

    2004-01-01

    Traditional PID controllers are no longer suitable for magnetic-bearing-supported high-speed flywheels with significant gyroscopic effects.Because gyroscopic effects greatly influence the stability of the flywheel rotor,especially at high rotational speeds.Velocity cross feedback and displacement cross feedback are used to overcome harmful effects of nutation and precession modes, and stabilize the rotor at high rotational speeds.Theoretical analysis is given to show their effects.A control platform based on RTLinux and a PC is built to control the active magnetic bearing (AMB) system, and relevant results are reported.Using velocity cross feedback and displacement cross feedback in a closed loop control system, the flywheel successfully runs at over 20 000 r/min.

  16. Development of a satellite flywheel family operating on one active axis magnetic bearings

    Poubeau, P. C.

    1977-01-01

    Since the samarium-cobalt magnets were available at industrial level, new possibilities appeared in the area of magnetic bearings with the radial passive centering and axial control of the rotor position. Magnetic bearings of this type on which a wide effort was made towards the optimization for satellite flywheel applications are described. Also, the momentum and reaction wheels were considered. This work was extended to the kinetic storage of energy for satellites.

  17. Vibration characterization of an active magnetic bearing supported rotor / J. Bean

    Bean, Jaco

    2011-01-01

    The McTronX Research group at the Potchefstroom campus of the North-West University, aims to establish a knowledge base on active magnetic bearing (AMB) systems. Up to date, the group has established a firm knowledge base on various topics related to AMB systems. A recent focus was the design and development of a high speed AMB supported rotor system called the rotor delevitation system (RDS) to analyse rotor drops. During the testing phase of the RDS, the machine exhibited vibrations, of whi...

  18. Active magnetic bearing control loop modeling for a finite element rotordynamics code

    Genta, Giancarlo; Delprete, Cristiana; Carabelli, Stefano

    1994-05-01

    A mathematical model of an active electromagnetic bearing which includes the actuator, the sensor and the control system is developed and implemented in a specialized finite element code for rotordynamic analysis. The element formulation and its incorporation in the model of the machine are described in detail. A solution procedure, based on a modal approach in which the number of retained modes is controlled by the user, is then shown together with other procedures for computing the steady-state response to both static and unbalance forces. An example of application shows the numerical results obtained on a model of an electric motor suspended on a five active-axis magnetic suspension. The comparison of some of these results with the experimental characteristics of the actual system shows the ability of the present model to predict its performance.

  19. Active magnetic bearing control loop modeling for a finite element rotordynamics code

    Genta, Giancarlo; Delprete, Cristiana; Carabelli, Stefano

    1994-01-01

    A mathematical model of an active electromagnetic bearing which includes the actuator, the sensor and the control system is developed and implemented in a specialized finite element code for rotordynamic analysis. The element formulation and its incorporation in the model of the machine are described in detail. A solution procedure, based on a modal approach in which the number of retained modes is controlled by the user, is then shown together with other procedures for computing the steady-state response to both static and unbalance forces. An example of application shows the numerical results obtained on a model of an electric motor suspended on a five active-axis magnetic suspension. The comparison of some of these results with the experimental characteristics of the actual system shows the ability of the present model to predict its performance.

  20. State of the art of control for magnetic levitation and magnetic bearing and control theory. Active control seigyo riron oyo no saisentan

    Nonami, K. (Chiba University, Chiba (Japan). Faculty of Engineering)

    1993-04-10

    From the viewpoint of control theory which was made known mainly through the papers presented in the international active magnetic bearing conference, survey was made of the latest state of active magnetic levitation and bearing system technology. The active magnetic bearing control system is applied to turbo-molecular pumps. They are analog PID-controlled rigid rotor pumps. Many of them are commonly characterized by five-axis controlled suction type active magnetic bearing. For heightening its performance, a further progress is being made in the following items of R and D: Transition from analog control to digital control using the digital signal processor. Transition from PID-controlled stabilization control to advanced control applying the modern control theory, robust control theory, learning control theory, and disturbance compensation control and other system designs. Active magnetic bearing control system with flexible rotors passing through the high order elastic mode. Active magnetic sensorless bearing by which the control is made by assuming the rotor displacement by the observer theory from the electric current in exciting coil. 37 refs., 11 figs.

  1. Accurate Wavelet Neural Network for Efficient Controlling of an Active Magnetic Bearing System

    Youssef Harkouss

    2010-01-01

    Full Text Available Problem statement: The synthesis of a command by the neural network has an excellent advantage over the classical one such as PID. This study presented a fast and accurate Wavelet Neural Network (WNN approach for efficient controlling of an Active Magnetic Bearing (AMB system. Approach: The proposed approach combined neural network with the wavelet theory. Wavelet theory may be exploited in deriving a good initialization for the neural network and thus improved convergence of the learning algorithm. Results: We tested two control systems based on three types of neural controllers: Multiplayer Perceptron (MLP controller, RBF Neural Network (RBFNN controller and WNN controller. The simulation results show that the proposed WNN controller provides better performance comparing with standard PID controller, MLP and RBFNN controllers. Conclusion: The proposed WNN approach was shown to be useful in controlling nonlinear dynamic mechanical system, such as the AMB system used in this study.

  2. Intelligent H2/H∞ Robust Control of an Active Magnetic Bearings System

    Safanah M.Raafat

    2015-06-01

    Full Text Available Robust controller design requires a proper definition of uncertainty bounds. These uncertainty bounds are commonly selected randomly and conservatively for certain stability, without regard for controller performance. This issue becomes critically important for multivariable systems with high nonlinearities, as in Active Magnetic Bearings (AMB System. Flexibility and advanced learning abilities of intelligent techniques make them appealing for uncertainty estimation. The aim of this paper is to describe the development of robust H2/H∞ controller for AMB based on intelligent estimation of uncertainty bounds using Adaptive Neuro Fuzzy Inference System (ANFIS. Simulation results reveal that the robust controller design objectives of wide bandwidth and improved performance are satisfied for a wide range of frequency variations. It can be concluded that the intelligent uncertainty weighting functions can precisely compensate for the effects of modelling errors and nonlinearities in the system.

  3. Theoretical and Experimental Investigation of Force Estimation Errors Using Active Magnetic Bearings with Embedded Hall Sensors

    Voigt, Andreas Jauernik; Santos, Ilmar

    2012-01-01

    of AMBs by embedding Hall sensors instead of mounting these directly on the pole surfaces, force estimation errors are investigated both numerically and experimentally. A linearized version of the conventionally applied quadratic correspondence between measured Hall voltage and applied AMB force is......This paper gives an original theoretical and experimental contribution to the issue of reducing force estimation errors, which arise when applying Active Magnetic Bearings (AMBs) with pole embedded Hall sensors for force quantification purposes. Motivated by the prospect of increasing the usability...... for pole embedded and pole surface mounted Hall sensors. It is shown that in a given range of bias currents and rotor offsets, pole embedded and surface mounted Hall sensors perform equally well for the four pole heteropolar flux-split radial AMB under investigation. Furthermore, frequency dependence...

  4. Development of active magnetic bearings and ferrofluid seals toward oil free sodium pumps

    Sreedhar, B.K., E-mail: bksd@igcar.gov.in; Kumar, R. Nirmal; Sharma, Prashant; Ruhela, Shivprakash; Philip, John; Sundarraj, S.I.; Chakraborty, N.; Mohana, M.; Sharma, Vijay; Padmakumar, G.; Nashine, B.K.; Rajan, K.K.

    2013-12-15

    Sodium centrifugal pumps employ conventional oil cooled bearings and mechanical seals to support the rotor assembly outside sodium and to seal the cover gas from the atmosphere. Although engineered safety features are incorporated in the design and detailed operational procedures formulated to ensure that no oil contamination of sodium can occur, there have been incidents of oil ingress into sodium. A design variant that eliminates the need for oil in top bearings and seals is therefore a promising option. This paper discusses the work in progress to develop a magnetic bearing and ferrofluid seal combination that can achieve this purpose.

  5. Development of active magnetic bearings and ferrofluid seals toward oil free sodium pumps

    Sodium centrifugal pumps employ conventional oil cooled bearings and mechanical seals to support the rotor assembly outside sodium and to seal the cover gas from the atmosphere. Although engineered safety features are incorporated in the design and detailed operational procedures formulated to ensure that no oil contamination of sodium can occur, there have been incidents of oil ingress into sodium. A design variant that eliminates the need for oil in top bearings and seals is therefore a promising option. This paper discusses the work in progress to develop a magnetic bearing and ferrofluid seal combination that can achieve this purpose

  6. Determination of Q-function optimum grid applied on active magnetic bearing control task

    Březina, Tomáš; Krejsa, Jiří

    Brno: VUT, 2003, s. 55-56. ISBN 80-214-2312-9. [Mechatronics, robotics and biomechanics 2003. Hrotovice (CZ), 24.03.2003-27.03.2003] R&D Projects: GA ČR GA101/00/1471 Institutional research plan: CEZ:AV0Z2076919 Keywords : control * magnetic bearing Subject RIV: BC - Control Systems Theory

  7. Magnetostatic analysis of a rotor system supported by radial active magnetic bearings

    Ferfecki P.

    2009-06-01

    Full Text Available The development and the design of a radial active magnetic bearing (AMB reflects a complex process of the multidisciplinary rotor dynamics, electromagnetism and automatic control analysis. Modelling is performed by application of the physical laws from different areas, e.g. Newton's laws of motion and Maxwell's equations. The new approach in the numerical modelling of radial AMB and design methodology allowing automatic generation of primary dimensions of the radial AMB is proposed. Instead of the common way of computation of electromagnetic forces by linearizing at the centre position of the rotor with respect to rotor displacement and coil current, the finite element computation of electromagnetic forces is used. The heteropolar radial AMB consisting of eight pole shoes was designed by means of the built up algorithms for rotor system with two discs fixed on the cantilever shaft. A study of the influence of the nonlinear magnetization characteristics of a rotor and stator material on the equilibrium position of a rotor system is carried out. The performed numerical study shows that results obtained from the analytical nonlinear relation for electromagnetic forces can be considerably different from forces computed with magnetostatic finite element analysis.

  8. Characteristic analysis of rotor dynamics and experiments of active magnetic bearing for HTR-10GT

    A 10 MW high-temperature gas-cooled reactor (HTR-10) was constructed by the Institute of Nuclear and New Energy Technology (INET) at Tsinghua University of China. The helium turbine and generator system of 10 MW high-temperature gas-cooled reactor (HTR-10GT) is the second phase for the HTR-10 project. It is to set up a direct helium cycle to replace the current steam cycle. The active magnetic bearing (AMB) instead of ordinary mechanical bearing was chosen to support the rotor in the HTR-10GT. This rotor is vertically mounted to hold the turbine machine, compressors and the power generator together. The rotor's length is 7 m, its weight is about 1500 kg and the rotating speed is 15,000 rpm. The structure of the rotor is so complicated that dynamic analysis of the rotor becomes difficult. One of the challenging problems is to exceed natural frequencies with enough stability and safety during reactor start up, power change and shutdown. The dynamic analysis of the rotor is the base for the design of control system. It is important for the rotor to exceed critical speeds. Some kinds of softwares and methods, such as MSC.Marc, Ansys, and the transfer matrix method (TMM), are compared to fully analyze rotor dynamics characteristic in this paper. The modal analysis has been done for the HTR-10GT rotor. MSC.Marc was finally selected to analyze the vibration mode and the natural frequency of the rotor. The effects of AMB stiffness on the critical speeds of the rotor were studied. The design characteristics of the AMB control system for the HTR-10GT were studied and the related experiment to exceed natural frequencies was introduced. The experimental results demonstrate the system functions and validate the control scheme, which will be used in the HTR-10GT project

  9. Characteristic analysis of rotor dynamics and experiments of active magnetic bearing for HTR-10GT

    A 10 MW high-temperature gas-cooled reactor (HTR-10) was constructed by the Institute of Nuclear and New Energy Technology (INET) at Tsinghua University of China. The helium turbine and generator system of 10 MW high temperature gas-cooled reactor (HTR-10GT) is the second phase for the HTR-10 project. It is to set up a direct helium cycle to replace the current steam cycle. The active magnetic bearing (AMB) instead of ordinary mechanical bearing was chosen to support the rotor in the HTR-10GT. This rotor is vertically mounted to hold the turbine machine, compressors and the power generator together. The rotor's length is 7 m, its weight is about 1500 kg and the rotating speed is 15000 r/min. The structure of the rotor is so complicated that dynamic analysis of the rotor becomes difficult. One of the challenging problems is to exceed natural frequencies with enough stability and safety during reactor start up, power change and shutdown. The dynamic analysis of the rotor is the base for the design of control system. It is important for the rotor to exceed critical speeds. Some kinds of software and methods, such as MSC.Marc, Ansys, and the Transfer Matrix Method, are compared to fully analyze rotor dynamics characteristic in this paper. The modal analysis has been done for the HTR-10GT rotor. MSC.Marc was finally selected to analyze the vibration mode and the natural frequency of the rotor. The effects of AMB stiffness on the critical speeds of the rotor were studied. The design characteristics of the AMB control system for the HTR-10GT were studied and the related experiment to exceed natural frequencies was introduced. The experimental results demonstrate the system functions and validate the control scheme, which will be used in the HTR-10GT project. (authors)

  10. Variable Parameters PD Control and Stability of a High Rate Rigid Rotor-Journal Active Magnetic Bearing System

    LUO Kai

    2005-01-01

    Stability is a key problem that means whether a high rate rotor-active magnetic bearings system works reliably or not. Aiming at a bearings system described with nonlinear equations, this paper built a linear model according to the system behavior. Considering realization of the control system and behavior of a high rate rotor system (magnetic force is far smaller than input force produced by mass eccentricity) this paper proposes a design method of variable parameters PD control algorithm that can be used universally. The control system was simplified and a mass of adjusting work of control parameters was reduced. Analysis and simulation indicated that the bearings system could get a wider stable region of harmonic motion, and proved that the algorithm is robust and advanced. The control system can be realized because the winding electric currents are positive. The method is convenient for operation and can easily be used for engineering practice.

  11. A self-sensing active magnetic bearing based on a direct current measurement approach.

    Niemann, Andries C; van Schoor, George; du Rand, Carel P

    2013-01-01

    Active magnetic bearings (AMBs) have become a key technology in various industrial applications. Self-sensing AMBs provide an integrated sensorless solution for position estimation, consolidating the sensing and actuating functions into a single electromagnetic transducer. The approach aims to reduce possible hardware failure points, production costs, and system complexity. Despite these advantages, self-sensing methods must address various technical challenges to maximize the performance thereof. This paper presents the direct current measurement (DCM) approach for self-sensing AMBs, denoting the direct measurement of the current ripple component. In AMB systems, switching power amplifiers (PAs) modulate the rotor position information onto the current waveform. Demodulation self-sensing techniques then use bandpass and lowpass filters to estimate the rotor position from the voltage and current signals. However, the additional phase-shift introduced by these filters results in lower stability margins. The DCM approach utilizes a novel PA switching method that directly measures the current ripple to obtain duty-cycle invariant position estimates. Demodulation filters are largely excluded to minimize additional phase-shift in the position estimates. Basic functionality and performance of the proposed self-sensing approach are demonstrated via a transient simulation model as well as a high current (10 A) experimental system. A digital implementation of amplitude modulation self-sensing serves as a comparative estimator. PMID:24030681

  12. A Self-Sensing Active Magnetic Bearing Based on a Direct Current Measurement Approach

    Carel P. du Rand

    2013-09-01

    Full Text Available Active magnetic bearings (AMBs have become a key technology in various industrial applications. Self-sensing AMBs provide an integrated sensorless solution for position estimation, consolidating the sensing and actuating functions into a single electromagnetic transducer. The approach aims to reduce possible hardware failure points, production costs, and system complexity. Despite these advantages, self-sensing methods must address various technical challenges to maximize the performance thereof. This paper presents the direct current measurement (DCM approach for self-sensing AMBs, denoting the direct measurement of the current ripple component. In AMB systems, switching power amplifiers (PAs modulate the rotor position information onto the current waveform. Demodulation self-sensing techniques then use bandpass and lowpass filters to estimate the rotor position from the voltage and current signals. However, the additional phase-shift introduced by these filters results in lower stability margins. The DCM approach utilizes a novel PA switching method that directly measures the current ripple to obtain duty-cycle invariant position estimates. Demodulation filters are largely excluded to minimize additional phase-shift in the position estimates. Basic functionality and performance of the proposed self-sensing approach are demonstrated via a transient simulation model as well as a high current (10 A experimental system. A digital implementation of amplitude modulation self-sensing serves as a comparative estimator.

  13. Optimal Control and H∞ Output Feedback Design Options for Active Magnetic Bearing Spindle Position Regulation

    Yifei Yang

    2013-07-01

    Full Text Available For the demand of high speed and high accuracy, the use of active magnetic bearing (AMB plays a key role in various industries such as clean rooms, compressors and satellites due to their contactless nature. In this research, two other control options for high speed machine were designed based on the optimal output feedback and H∞ output feedback control methods to improve the radical and axial position regulation of AMB. The output feedback control gain matrix with the minimum performance index is obtained by solving the Riccati equation and fed back to the system in order to achieve the system’s performance. The above designed controllers can efficiently regulate the radial and axial directions position deviation of for AMB systems. Simulations for the two control methods were carried out using Matlab and Simulink for AMB system models. Results show that the H∞ output feedback controller has a better position deviation control performance over the optimal output feedback under condition of decreasing the disturbance of reaction. Finally, simulations results demonstrate that the H∞ Output Feedback is effective.

  14. Nonlinear Control of Magnetic Bearings

    Khac Duc Do; Dang Hoe Nguyen; Thanh Binh Nguyen

    2010-01-01

    In this paper, recent results controling nonlinear systems with output tracking error constraints are applied to the design of new tracking controllers for magnetic bearings. The proposed controllers can force the rotor to track a bounded and sufficiently smooth refer-ence trajectory asymptotically and guarantee non-contactedness be-tween the rotor and the stator of the magnetic bearings. Simulation results are included to illustrate the effectiveness of the proposed con-trollers.

  15. Thin film superconductor magnetic bearings

    Weinberger, Bernard R.

    1995-12-26

    A superconductor magnetic bearing includes a shaft (10) that is subject to a load (L) and rotatable around an axis of rotation, a magnet (12) mounted to the shaft, and a stator (14) in proximity to the shaft. The stator (14) has a superconductor thin film assembly (16) positioned to interact with the magnet (12) to produce a levitation force on the shaft (10) that supports the load (L). The thin film assembly (16) includes at least two superconductor thin films (18) and at least one substrate (20). Each thin film (18) is positioned on a substrate (20) and all the thin films are positioned such that an applied magnetic field from the magnet (12) passes through all the thin films. A similar bearing in which the thin film assembly (16) is mounted on the shaft (10) and the magnet (12) is part of the stator (14) also can be constructed.

  16. The development on-line monitoring system of active magnetic bearings for HTR-10GT

    High Temperature Gas-cooled Reactor (HTR) is recognized as an advanced type of reactor incorporating many design enhancements such as inherent safety features, fuel cycle flexibility, highly fuel utilization, highly efficient electricity generation and process heat application. The research and development of HTR started at the middle of the 1970's, and came to be a part of the Chinese High Technology Program in 1986. A plan to build a 10 MW High Temperature Gas-cooled Reactor (HTR-10) was approved by the State Science and Technology Commission in 1990, and in 1995 the construction was initiated at the Institute of Nuclear Energy Technology (INET), Tsinghua University. The full power 10 MW operation for 72 hours have reached in 2003, and have been checked and accepted by the State Science and Technology Commission. In order to advance the HTR-10 performance, the project of the Helium Gas Turbine Generator for the HTR-10 was authorized by the State Science and Technology Commission, and stared in 2003. In this project, active magnetic bearings (AMBs) are chosen to support the generator rotor and the turbocompressor rotor in the power conversion unit because of their numerous advantages over the conventional bearings. In order to detect how the AMB system works in operation and make diagnosis whether the system behaves normally or not, the monitoring system based on the virtual instruments is designed to monitor the working conditions of the PCU, and to ensure its normal operation. This monitoring system consists of the industry personal computer (PC), the data acquisition system, the measurement transmitters and the LabVIEW system platform. It is located at the PCU control room, and communicates with the master control room by Controller Area Net (CAN). The development is divided into the following three steps: First, a data acquisition platform to collect and acquire all the necessary and useful data from the operation of the AMB system is developed. Second, the

  17. Passive axial stabilization of a magnetic radial bearing by superconductors

    Marinescu, M.; Marinescu, N. (Ing.-Buro f. Magnettechnik, Mailander Str.19, D-6000 Frankfurt/M. 70 (DE)); Tenbrink, J.; Krauth, H. (Vacuumschmelze GmbH, Gruner Weg 37, D-6450 Hanau (DE))

    1989-09-01

    Contactless bearings for high-speed operation can be constructed using passive magnet systems, which inherently need a second, active bearing for their stabilization. Completely passive bearings only can be obtained using diamagnetic materials. This study deals with the axial stabilization of magnetic radial bearings using a permanent magnet/superconductor system. Using finite element calculation procedures it is shown that axial forces of up 3000 N and stiffnesses of up to 400 N/mm may be achieved.

  18. 主动电磁轴承系统的动力学性能分析%Analysis on Dynamic Performance for Active Magnetic Bearing-Rotor System

    严慧燕; 汪希平; 朱礼进; 张直明; 万金贵

    2001-01-01

    In the application of active magnetic bearings (AMB), one of the key problems to be solved is the safety and stability in the sense of rotor dynamics. The project related to the present paper deals with the method for analyzing bearing rotor systems with high rotation speed and specially supported by active magnetic bearings, and studies its rotor dynamics performance, including calculation of the natural frequencies with their distribution characteristics, and the critical speeds of the system. One of the targets of this project is to formulate a theory and method valid for the analysis of the dynamic performance of the active magnetic bearing-rotor system by combining the traditional theory and method of rotor dynamics with the analytical theory and design method based on modern control theory of the AMB system.

  19. Unbalanced Magnetic Pull Effect on Stiffness Models of Active Magnetic Bearing due to Rotor Eccentricity in Brushless DC Motor Using Finite Element Method

    Bangcheng Han

    2013-01-01

    Full Text Available We firstly report on an investigation into the unbalanced magnetic pull (UMP effect on the static stiffness models of radial active magnetic bearing (RAMB in brushless DC motor (BDCM in no-loaded and loaded conditions using the finite element method (FEM. The influences of the UMP on the force-control current, force-position, current stiffness, and position stiffness of RAMB are clarified in BDCM with 100 kW rated power. We found the position stiffness to be more susceptible to UMP. The primary source of UMP is the permanent magnets of BDCM. In addition, the performance of RAMB is affected by the UMP ripples during motor commutation and also periodically affected by the angular position of rotor. The characteristic curves of RAMB force versus control current (or rotor position and angular position of rotor affected by the UMP are given. The method is useful in design and optimization of RAMB in magnetically suspended BDCMs.

  20. Controller Design and Validation of Radial Active Magnetic Bearing Systems Considering Dynamical Changes Due To Rotational Speeds

    If a rotor possesses a high gyroscopic coupling or the running speed is high, the dynamical changes in the rotor become prominent. When active magnetic bearings are used to support such rotors, it is necessary for the bearing controller to take these dynamical changes into consideration. Independent-axis controllers, which are the most commonly used, modulate the bearing force solely based on the sensor output of the same axis. However, this type of controller has difficulties in overcoming the dynamical changes. On the other hand, mixed-axis controllers transform the sensor output into components corresponding to the vibrational modes. A separate controller can then be designed for each vibrational mode. In this way, the controller can be designed based on the dynamics of the rotor. In this paper, we describe a design process for a mixed-axis controller that uses a detailed mathematical model of the system. The performance of the controller is evaluated based on the ISO sensitivity requirements and unbalance response, while considering the change in the system dynamics due to the running speed

  1. Hydrodynamic Effects on Modeling and Control of a High Temperature Active Magnetic Bearing Pump with a Canned Rotor

    Melin, Alexander M [ORNL; Kisner, Roger A [ORNL; Fugate, David L [ORNL; Holcomb, David Eugene [ORNL

    2015-01-01

    Embedding instrumentation and control Embedding instrumentation and control (I\\&C) at the component level in nuclear power plants can improve component performance, lifetime, and resilience by optimizing operation, reducing the constraints on physical design, and providing on-board prognostics and diagnostics. However, the extreme environments that many nuclear power plant components operate in makes embedding instrumentation and control at the component level difficult. Successfully utilizing embedded I\\&C requires developing a deep understanding of the system's dynamics and using that knowledge to overcome material and physical limitations imposed by the environment. In this paper, we will develop a coupled dynamic model of a high temperature (700 $^\\circ$C) canned rotor pump that incorporates rotordynamics, hydrodynamics, and active magnetic bearing dynamics. Then we will compare two control design methods, one that uses a simplified decoupled model of the system and another that utilizes the full coupled system model. It will be seen that utilizing all the available knowledge of the system dynamics in the controller design yield an order of magnitude improvement in the magnitude of the magnetic bearing response to disturbances at the same level of control effort, a large reduction in the settling time of the system, and a smoother control action.

  2. Preliminary modal analysis and structure design of an HTR-10 PCU rotor with an active magnetic bearing

    A 10 MW high-temperature gas-cooled reactor (HTR-10) was constructed by INET at Tsinghua University of China. The second phase of the HTR-10 project is to set up a direct helium cycle to replace the current steam cycle. An Active Magnetic Bearing (AMB) was chosen to support the rotor. This rotor is vertically mounted to hold the turbine machine, compressors and the power generator together. The rotor's length is 7 m, its weight is about 1000 kg and the rotating speed is 15,000 r/min. One of the challenging problems is to exceed natural frequencies with enough stability and safety during reactor start up, power change and shutdown. Some kinds of FEM software and methods, such as MSC.Marc, Ansys, and the Transfer Matrix Method, are compared to fully analyze rotor dynamics characteristic. The modal analysis and preliminary structure design have been done for the HTR-10 phase II rotor. MSC.Marc was finally selected to analyze the vibration mode and the natural frequency of the rotor. The effects of AMB stiffness on the critical speeds of the rotor were studied. These results offer the basis for design of the AMB control system, and also provide research data for large magnetic bearings. (author)

  3. Sensorless Control of Axial Magnetic Bearings

    Atsumo, Daichi; Yoshida, Toshiya; Ohniwa, Katsumi

    This paper describes a sensorless control method of axial active magnetic bearings (AMBs). At high frequencies, inductance of the axial electromagnets is hardly dependent on the airgap because of the eddy current effects of the non-laminated core. Therefore the carrier frequency should be 3 kHz below to improve the sensitivity to the airgap. In the experiment, Sensorless controll of the axial AMBs have been achieved.

  4. Technical design and principle test of active magnetic bearings for the turbine compressor of HTR-10GT

    Shi Lei, E-mail: shlinet@tsinghua.edu.cn [Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084 (China); Yu Suyuan; Yang Guojun; Shi Zhengang; Xu Yang [Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084 (China)

    2012-10-15

    The 10 MW high temperature gas-cooled test reactor coupled with gas-turbine circle (HTR-10GT) has been carried out by the Institute of Nuclear and New Energy Technology (INET) of Tsinghua University in China since year 2002. In the power convention unit (PCU) of the HTR-10GT, the contact-free and no-lubricating active magnetic bearings (AMB) are adopted to support the vertical high-speed turbine machine shaft, because of their numerous advantages over the conventional oil mechanical bearings under the special reactor operating conditions. Based on the previous studies and small tests of the AMBs, the final engineering design of the AMBs for the HTR-10GT turbine compressor rotor has been finished recently. This paper firstly introduces the design principle and technical futures of the AMBs. Then the main structure, as well as the key dimensions and parameters of the different AMB components are illustrated in detail. Besides, the rotor dynamic analysis is conducted to provide the mathematic model for the unbalance attenuation with high performance control system design in order to smoothly pass across the first two bending critical speeds before reaching the rated speed of 15,000 rpm. Furthermore, a small AMB flexible test system in compliance with the dynamic similarity principle of the helium turbine compressor rotor of the HTR-10GT, has been set up to validate the advanced control algorithms and accumulate design and operation experiences for the next full scale experiment in the near future.

  5. Technical design and principle test of active magnetic bearings for the turbine compressor of HTR-10GT

    The 10 MW high temperature gas-cooled test reactor coupled with gas-turbine circle (HTR-10GT) has been carried out by the Institute of Nuclear and New Energy Technology (INET) of Tsinghua University in China since year 2002. In the power convention unit (PCU) of the HTR-10GT, the contact-free and no-lubricating active magnetic bearings (AMB) are adopted to support the vertical high-speed turbine machine shaft, because of their numerous advantages over the conventional oil mechanical bearings under the special reactor operating conditions. Based on the previous studies and small tests of the AMBs, the final engineering design of the AMBs for the HTR-10GT turbine compressor rotor has been finished recently. This paper firstly introduces the design principle and technical futures of the AMBs. Then the main structure, as well as the key dimensions and parameters of the different AMB components are illustrated in detail. Besides, the rotor dynamic analysis is conducted to provide the mathematic model for the unbalance attenuation with high performance control system design in order to smoothly pass across the first two bending critical speeds before reaching the rated speed of 15,000 rpm. Furthermore, a small AMB flexible test system in compliance with the dynamic similarity principle of the helium turbine compressor rotor of the HTR-10GT, has been set up to validate the advanced control algorithms and accumulate design and operation experiences for the next full scale experiment in the near future.

  6. Modal Tilt/Translate Control and Stability of a Rigid Rotor with Gyroscopics on Active Magnetic Bearings

    Timothy Dimond

    2012-01-01

    Full Text Available Most industrial rotors supported in active magnetic bearings (AMBs are operated well below the first bending critical speed. Also, they are usually controlled using proportional, integral and derivative controllers, which are set up as modally uncoupled parallel and tilt rotor axes. Gyroscopic effects create mode splitting and a speed-dependent plant. Two AMBs with four axes of control must simultaneously control and stabilize the rotor/AMB system. Various analyses have been published considering this problem for different rotor/AMB configurations. There has not been a fully dimensionless analysis of these rigid rotor AMB systems. This paper will perform this analysis with a modal PD controller in terms of translation mode and tilt mode dimensionless eigenvalues and eigenvectors. The number of independent system parameters is significantly reduced. Dimensionless PD controller gains, the ratio of rotor polar to transverse moments of inertia and a dimensionless speed ratio are used to evaluate a fully general system stability rigid rotor analysis. An objective of this work is to quantify the effects of gyroscopics on rigid rotor AMB systems. These gyroscopic forces reduce the system stability margin. The paper is also intended to help provide a common framework for communication between rotating machinery designers and controls engineers

  7. High performance magnetic bearings suitable for noise cancellation in permanent magnet motor driven pumps

    Conventional pumps having external drive motors experience problems due to bearing noise. In addition failure of bearings and seals can lead to limited operational reliability and impaired integrity of these pumps. Pumps using DC brushless motors and magnetic bearings offer means of overcoming these problems. A design of a pump having a DC brushless motor and magnetic bearings with a potential for Naval applications in ships and submarines is discussed. In this paper attention is given to the selection of the magnetic bearings suitable for achieving active noise cancellation

  8. Design, construction, and testing of a five active axes magnetic bearing system

    Delprete, Cristiana; Genta, Giancarlo; Carabelli, Stefano

    1994-05-01

    A high speed electric spindle based on active electromagnetic suspension technology has been designed, built, and tested. The main goal of the research work was the construction of a highly modular unit which can be used for teaching and research purposes. The design of the electromechanical components and of the control unit is described in detail, together with the characterization tests performed on the various subsystems. A description of the preliminary tests on the unit, conducted at speeds not in excess of the first deformation critical speed of the rotor, concludes the work.

  9. Design, construction, and testing of a five active axes magnetic bearing system

    Delprete, Cristiana; Genta, Giancarlo; Carabelli, Stefano

    1994-01-01

    A high speed electric spindle based on active electromagnetic suspension technology has been designed, built, and tested. The main goal of the research work was the construction of a highly modular unit which can be used for teaching and research purposes. The design of the electromechanical components and of the control unit is described in detail, together with the characterization tests performed on the various subsystems. A description of the preliminary tests on the unit, conducted at speeds not in excess of the first deformation critical speed of the rotor, concludes the work.

  10. Passive Magnetic Bearing With Ferrofluid Stabilization

    Jansen, Ralph; DiRusso, Eliseo

    1996-01-01

    A new class of magnetic bearings is shown to exist analytically and is demonstrated experimentally. The class of magnetic bearings utilize a ferrofluid/solid magnet interaction to stabilize the axial degree of freedom of a permanent magnet radial bearing. Twenty six permanent magnet bearing designs and twenty two ferrofluid stabilizer designs are evaluated. Two types of radial bearing designs are tested to determine their force and stiffness utilizing two methods. The first method is based on the use of frequency measurements to determine stiffness by utilizing an analytical model. The second method consisted of loading the system and measuring displacement in order to measure stiffness. Two ferrofluid stabilizers are tested and force displacement curves are measured. Two experimental test fixtures are designed and constructed in order to conduct the stiffness testing. Polynomial models of the data are generated and used to design the bearing prototype. The prototype was constructed and tested and shown to be stable. Further testing shows the possibility of using this technology for vibration isolation. The project successfully demonstrated the viability of the passive magnetic bearing with ferrofluid stabilization both experimentally and analytically.

  11. A CAD approach to magnetic bearing design

    Jeyaseelan, M.; Anand, D. K.; Kirk, J. A.

    1988-01-01

    A design methodology has been developed at the Magnetic Bearing Research Laboratory for designing magnetic bearings using a CAD approach. This is used in the algorithm of an interactive design software package. The package is a design tool developed to enable the designer to simulate the entire process of design and analysis of the system. Its capabilities include interactive input/modification of geometry, finding any possible saturation at critical sections of the system, and the design and analysis of a control system that stabilizes and maintains magnetic suspension.

  12. Using Magnetic Bearing Orbit Information to Maximize Centrifugal Compressor Efficiency at Off-Design Conditions

    Thornton, W. Turner; Brasz, Joost J.

    2014-01-01

    Active magnetic bearings used on oil-free centrifugal refrigeration compressors have lower stiffness than conventional oil-lubricated journal or rolling element bearings. The lower stiffness of these bearings makes them sensitive to internal flow instabilities that are precursors of rotating stall or compressor surge. At operating conditions far away from surge the internal flow is very stable and the magnetic bearings keep the shaft centered, resulting in a minimal bearing orbit. The interna...

  13. Flywheel energy storage with superconductor magnetic bearings

    Weinberger, Bernard R.; Lynds, Jr., Lahmer; Hull, John R.

    1993-01-01

    A flywheel having superconductor bearings has a lower drag to lift ratio that translates to an improvement of a factor of ten in the rotational decay rate. The lower drag results from the lower dissipation of melt-processed YBCO, improved uniformity of the permanent magnet portion of the bearings, operation in a different range of vacuum pressure from that taught by the art, and greater separation distance from the rotating members of conductive materials.

  14. AN INVESTIGATION OF MAGNETIC BEARING SYSTEMS

    Gürcan SAMTAŞ

    2007-02-01

    Full Text Available The magnetic bearing consists of levitating a shaft so that it is free to rotate about its axis. The magnetic bearing has the advantages of being very quiet work and very cleanliness because there is no mechanical friction or lubricants. The shaft has two permanent magnets attached to it. These two magnets determine a straight line rotation axis of the rotor shaft. The magnets are radially levitated and centered within a cavity by a passive permanent magnetic field in the adding stator housing assembly. The levitation and centering of the shaft axially is stabilized by a closed loop electronic servo circuit that regulates an electromagnetic field in the stator housing that pushes and pulls on the shaft magnets. The rotor weight can be between one gram and forty five thousand, four hundred grams. In 1985, the first magnetic bearing was developed that it had used to applications of gas turbines and other compressors. In these days, they can be used by many applications which are Medical, Transportation, Machine and Tools Industry, Aerospace, Vacuum and Clean room Environments... etc.

  15. Magnetic bearings for free-piston Stirling engines

    Curwen, P. W.; Fleming, D. P.; Rao, D. K.; Wilson, D. S.

    1992-08-01

    The feasibility and efficacy of applying magnetic bearings to free-piston Stirling-cycle power conversion machinery currently being developed for long-term space missions are assessed. The study was performed for a 50-kWe Reference Stirling Space Power Converter (RSSPC) which currently uses hydrostatic gas bearings to support the reciprocating displacer and power piston assemblies. Active magnetic bearings of the attractive electromagnetic type are feasible for the RSSPC power piston. Magnetic support of the displacer assembly would require unacceptable changes to the design of the current RSSPC. However, magnetic suspension of both displacer and power piston is feasible for a relative-displacer version of the RSSPC. Magnetic suspension of the RSSPC power piston can potentially increase overall efficiency by 0.5 to 1 percent (0.1 to 0.3 efficiency points). Magnetic bearings will also overcome several operational concerns associated with hydrostatic gas bearing systems. These advantages, however, are accompanied by a 5 percent increase in specific mass of the RSSPC.

  16. Weak and strong nonlinearities in magnetic bearings

    Půst, Ladislav

    2004-01-01

    Roč. 39, č. 7 (2004), s. 779-795. ISSN 0094-114X R&D Projects: GA ČR GA101/00/1471; GA AV ČR IBS2076301 Institutional research plan: CEZ:AV0Z2076919 Keywords : weak nonlinearitiy * strong nonlinearity * magnetics bearings Subject RIV: BI - Acoustics Impact factor: 0.605, year: 2004

  17. MAGNETIC FLUID BEARINGS OF MINING EQUIPMENT

    I. Gorlov

    2012-01-01

    Full Text Available The paper considers a problem pertaining to selection friction pair materials for plain bearings of mining equipment which are lubricated with  nano-dispersed magnetic oil. Methodology for equipment tests, technology for obtaining new anti-friction materials (polymer, ceramic, amorphous and investigation results are presented in the paper.

  18. Dynamic interaction between rotor and axially-magnetized passive magnetic bearing considering magnetic eccentricity

    Enemark, Søren; Santos, Ilmar

    2014-01-01

    Passive magnetic bearings are known due to the excellent characteristics in terms of friction and no requirement of additional energy sources to work. However, passive magnetic bearings do not provide damping, are not stable and, depending on their design, may also introduce magnetic eccentricity....... Such magnetic eccentricities are generated by discrepancies in magnet fabrication. In this framework the main focus of the work is the theoretical as well as experimental investigation of the nonlinear dynamics of a rotor-bearing system with strong emphasis on the magnetic eccentricities and non......-linear stiffness. In this investigation passive magnetic bearings using axially- aligned neodymium cylinder magnets are investigated. The cylinder magnets are axially magnetised for rotor as well as bearings. Compared to bearings with radial magnetisation, the magnetic stiffness of axially-aligned bearings is...

  19. Novel High Temperature Magnetic Bearings for Space Vehicle Systems Project

    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...

  20. Novel High Temperature Magnetic Bearings for Space Vehicle Systems Project

    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...

  1. Permanent magnet design for high-speed superconducting bearings

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

    1996-09-10

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

  2. Dynamic modelling and response characteristics of a magnetic bearing rotor system with auxiliary bearings

    Free, April M.; Flowers, George T.; Trent, Victor S.

    1995-01-01

    Auxiliary bearings are a critical feature of any magnetic bearing system. They protect the soft iron core of the magnetic bearing during an overload or failure. An auxiliary bearing typically consists of a rolling element bearing or bushing with a clearance gap between the rotor and the inner race of the support. The dynamics of such systems can be quite complex. It is desired to develop a rotordynamic model which describes the dynamic behavior of a flexible rotor system with magnetic bearings including auxiliary bearings. The model is based upon an experimental test facility. Some simulation studies are presented to illustrate the behavior of the model. In particular, the effects of introducing sideloading from the magnetic bearing when one coil fails is studied.

  3. Dynamic modelling and response characteristics of a magnetic bearing rotor system including auxiliary bearings

    Free, April M.; Flowers, George T.; Trent, Victor S.

    1993-01-01

    Auxiliary bearings are a critical feature of any magnetic bearing system. They protect the soft iron core of the magnetic bearing during an overload or failure. An auxiliary bearing typically consists of a rolling element bearing or bushing with a clearance gap between the rotor and the inner race of the support. The dynamics of such systems can be quite complex. It is desired to develop a rotor-dynamic model and assess the dynamic behavior of a magnetic bearing rotor system which includes the effects of auxiliary bearings. Of particular interest is the effects of introducing sideloading into such a system during failure of the magnetic bearing. A model is developed from an experimental test facility and a number of simulation studies are performed. These results are presented and discussed.

  4. Analysis of Beat Vibration for Active Magnetic Bearing System%主动磁悬浮轴承系统拍振现象分析

    高辉; 徐龙祥

    2011-01-01

    Vibration analysis plays an important role in the research of active magnetic bearing(AMB) system. However, the established system mathematical models which combine the controller with the dynamic response are relatively few. The vibration equations of radial AMB subsystems are built on the basis of the stress analysis of high speed rotor system, referring the influences of the frequency characteristics of adopted incomplete differential PID controller on the generalized magnetic bearing dynamic stiffness and rotor dynamic unbalance response. The vibration modes existing in AMB system can be obtained by solving the vibration equations. One is free vibration because of the inherent frequency, and the other is harmonic vibration due to unbalanced excitation response. And the produced beat vibration phenomenon is explained when the two kinds of vibration frequency are similar. Through adjusting the control current, the generalized dynamic stiffness of magnetic bearings and as well as the inherent frequency of the system can be changed, thus resulting in the weakening of beat vibration. Simulation and experimental results can verify the "beat vibration" phenomenon and the damping effect after changing the active control. The mechanical model can provide the simulation platform for the research of vibration compensation algorithm of AMB system.%振动分析是研究主动磁悬浮轴承(Active magnetic bearings,AMB)系统的一个重要部分,但是目前结合控制器以及动态不平衡响应建立的系统数学模型相对较少.通过对高速主动磁悬浮轴承转子系统受力分析,参考所使用的不完全微分PID控制器的频率特性对AMB广义动刚度的影响以及对转子动态不平衡激励响应的影响,建立径向子系统的力学振动方程.通过此振动方程的解,得出AMB系统存在的振动形式.一种是由于系统固有频率存在而产生的自由振动,另一种是由于不平衡响应存在而产生的简谐振动,并

  5. Development of bearings and a damper based on magnetically controllable fluids

    Guldbakke, J. M.; Hesselbach, J.

    2006-09-01

    This paper presents two different kinds of magnetically controllable fluid bearings and a new magnetorheological fluid damper based upon open porous metallic foams. For the bearings, it will distinguish between a magnetohydrostatic bearing and a hydrostatic bearing with a magnetically controllable fluid. The magnetohydrostatic bearings get their load bearing capacity from the magnetohydrostatic pressure that is generated by the gradient of the magnetic field along a fluid surface. With such magnetohydrostatic bearings a specific load up to 1.6 N cm2 can be reached. To support heavier loads hydrostatic bearings with magnetically controllable fluids can be used. This bearing concept makes it possible to achieve a constant bearing gap even if the load of the bearing changes. For this purpose the fluids are used as a hydraulic medium. Due to the magnetically controlled rheological behaviour of the fluid the bearing gap remains constant. The great advantage of this closed loop system compared to that of common hydrostatic bearings using valves is the quicker response to payload changes. The reason for that is that the active element (i.e. the fluid) acts directly inside the bearing gap and not outside like in the case of valves. The foam damper developed uses the fluid to produce controllable damping forces. The open porous foam is directly placed in the active volume of the damper. By moving the foam piston the magnetically controllable fluid is pressed through the pores. The flow in the pores can be controlled by changing the fluid viscosity by applying a magnetic field. With this damper structure it is possible to reach higher damping forces whilst featuring a small design space.

  6. Modeling of Hybrid Permanent Magnetic-Gas Bearings

    Morosi, Stefano; Santos, Ilmar

    2009-01-01

    Modern turbomachinery applications require nowadays ever-growing rotational speeds and high degree of reliability. It then becomes natural to focus the attention of the research to contact-free bearings elements. The present alternatives focus on gas lubricated journal bearings or magnetic bearings....... In the present paper both the technologies are combined with the aim of developing a new kind of hybrid permanent magnetic - gas bearing. This new kind of machine is intended to exploit the benefits of the two technologies while minimizing their drawbacks. The poor start-up and low speed operation...... performance of the gas bearing is balanced by the properties of the passive magnetic one. At high speeds the dynamic characteristics of the gas bearing are improved by offsetting the stator ring of the permanent magnetic bearing. Furthermore this design shows a kind of redundancy, which offers soft failure...

  7. 风力发电机用同极型磁悬浮轴承的支承性能%Supporting characteristics of the homopolar active magnetic bearing for wind power generator

    谢振宇; 王晓; 周红凯

    2013-01-01

    The setup of vertical axis wind power generator rotor system is built. The homopolar radial active magnetic bearing and the axial active magnetic bearing with the function of suspension and brake synchronously are designed and manufactured. The main design process and configuration parameters are presented. Stability ranges of the control parameters of the active magnetic bearings are tested, the mode frequencies and modal damps of the system are obtained by experimental modal analysis, and the brake function of the axial active magnetic bearing is verified. The results show that the first critical speed of the system is far above the operating rotation speed, there is no resonance when the system is in motion. On the other hand, the axial active magnetic bearing can meet the brake demand and reduce the size and cost of the system.%建立了垂直轴风力发电机转子系统装置,设计制作了同极型径向磁悬浮轴承和具有悬浮与刹车功能的轴向磁悬浮轴承,给出了该装置的主要设计过程和结构参数.测试了磁悬浮轴承控制参数的稳定区域,采用试验模态分析方法获取了系统的模态频率和模态阻尼,并验证了轴向磁悬浮轴承的刹车功能.结果表明,系统的第一阶临界转速远高于最大工作转速,系统在运行时不会出现共振;另外,轴向磁悬浮轴承可以满足刹车制动要求,有利于减小系统的体积和成本.

  8. Toxicity of Magnetic Albumin Microspheres Bearing Adriamycin

    2000-01-01

    Magnetic albumin microspheres bearing adriamycin (ADM-MAM) is a novel chemotherapeutic compound with site-specific drug delivery characteristics. The acute and subacute toxic tests of the compound, local irritating test and anaphylactic test were performed on mice and guinea pigs. The results showed there was no macroscopically and microscopically direct cytotoxic injuries of the compound to the animal organs or to the cells. The LD50 value of the compound was higher than that of the single used adriamycin, indicating that the compound was less toxic than the single adriamycin and quite safe in its therapeutic dosage. Furthermore, there was also no side effects or toxic reactions to be observed on clinical patients with advanced carcinoma or gastric cancer.

  9. Analysis of Permanent Magnets Bearings in Flywheel Rotor Designs

    Prince Owusu-Ansah

    2016-04-01

    Full Text Available This paper discusses analysis of permanent magnet bearing in flywheel rotor designs. This work focuses on the advantages of using permanent magnets in flywheel rotor design as compared to that of the convectional mode of levitating the rotor position. The use of permanent magnet in magnetic bearing design to generate the steady state position of the magnetic field results in less variation of the force exerted on the rotor when it deviates from the nominal position than when an electrical coil is used for the same purpose. Theresults of the analysis shows that the magnetic bearing dynamics as well as its load carryingcapacity improves when the rotor is offset from its central position. The use of permanent magnet compared to current-carrying coils results in smaller overall size of magnetic bearing leading to a more compact system design resulting in improved rotordynamic performance

  10. Suppression of Base Excitation of Rotors on Magnetic Bearings

    Steven Marx; C. Nataraj

    2007-01-01

    This paper deals with rotor systems that suffer harmonic base excitation when supported on magnetic bearings. Magnetic bearings using conventional control techniques perform poorly in such situations mainly due to their highly nonlinear characteristics. The compensation method presented here is a novel optimal control procedure with a combination of conventional, proportional, and differential feedback control. A four-degree-of-freedom model is used for the rotor system, and the bearings are ...

  11. Performances Comparison for a Rotating Shaft Suspended by 4-Axis Radial Active Magnetic Bearings via -Synthesis, Loop-Shaping Design, and Sub(∞with Uncertainties

    G. Barbaraci

    2011-01-01

    Full Text Available The control systems applied on active magnetic bearing are several. A perfect levitation is characterized by maintaining the operating point condition that is characterized by the center of stator coincident with the geometric center of shaft. The first controller implemented for this purpose is PID controller that is characterized by an algorithm that leads the amplifier to produce control current until the operating point condition is not reached, this is obtained by an integration operator. The effect of an integrator is essential but not necessary for a centered levitation for example in the robust control characterized by a dynamic model depended on plant of system so that it depends on angular speed as LQR controller does. In LQR there is not integrator so there is not a perfectly centered section of shaft with center of stator. On contrary PID controller does not depend on angular speed and it can be easily implemented according some simple rules. Predictive control is another interesting controller characterized by a multiple controller operating in different condition in order to get the minimum of cost function, but also in this case the angular speed is introduce for the same reason discussed before.

  12. Early-stage fault isolation based on frequency response fitted by small-size samples for cryogenic cold compressors with active magnetic bearings.

    Arpaia, Pasquale; De Vito, Luca; Girone, Mario; Pezzetti, Marco

    2016-01-01

    A model-based method for fault detection and early-stage isolation, applicable when unfaulty conditions can be identified only by a reduced number of trials (even only one), is presented. The basic idea is to model analytically the uncertainty of the unfaulty frequency response and express the fault condition in terms of the noise power variance. A preliminary fault isolation is carried out by sensitivity analysis in order to identify the most influencing model parameters and assess their influence on the estimated noise. Then, during maintenance tests, the noise power is checked to detect the faulty condition. This technique is conceived to check the quality of a critical component in an experimental installation (fault detection and early-stage isolation), as well as to detect its faulty dynamic behaviors over a long horizon maintenance test campaign (condition monitoring). The method was applied to four cold compressors with active magnetic bearings at CERN by proving to be able to detect an actual faulty condition in one of such compressors. PMID:26827354

  13. Biodegradation reduces magnetization in oil bearing rocks: magnetization results of a combined chemical and magnetic study

    Emmerton, S.; Muxworthy, A. R.; Sephton, M. A.; Williams, W.

    2012-12-01

    A relationship between hydrocarbons and their magnetic signatures has been alluded to for decades but this is the first study to combine geochemical and magnetic data. We report an extended study that identifies a definitive connection between magnetic mineralogy and biodegradation within oil-bearing rocks. Samples from Colombia, Canada Indonesia and the UK were collected and magnetically characterized. A negative linear regression in log space between magnetic susceptibility and the percentage of extractable organic matter was observed for individual reservoirs. To determine if this relationship is due to the activity of bacteria or migration of the oil, the percentage of oil components; aliphatic, aromatics, polars and resins and the biodegradation state of the samples were compared to the magnetic susceptibility and magnetic mineralogy of the samples. Geochemical biomarker data revealed that all oil samples were derived from mature type-II kerogen, which was deposited in oxygen-poor environments allowing for an investigation into biodegradation variations. Biodegradation is the decrease of oil quality through the conversion of aliphatic hydrocarbons to polar constituents mainly through the activity of bacteria. A distinct decrease in magnetic susceptibility was correlated to decreasing oil quality (loss of aliphatic hydrocarbons, more biodegraded), which cannot be rejected at 99% confidence. Further magnetic characterization revealed that the high quality, low biodegradation oils from Colombia have a higher magnetic susceptibility (10-3-10-4 m3kg-1) and are dominated by pseudo-single domain grains of magnetite. The lower quality oils i.e., the UK, Canadian and Indonesian samples, displayed decreased magnetic susceptibility (10-5-10-6 m3kg-1) and pseudo-single domain to multidomain grains of magnetite and hematite. Magnetite and pyrrhotite framboidal material were found in all but the Canadian samples. Therefore, with decreasing oil quality there is a progressive

  14. THE EDDY LOSSES OF A MAGNETIC THRUST BEARING

    徐华; 王艳

    2004-01-01

    Accurate calculations of losses associated with the operation of magnetic bearings are particularly important for high speed applications where the rotor losses are expected to be large and for some particular applications where even low power losses will be critical. Power losses in the magnetic thrust bearing is often neglected, but if there is misaligned in the rotor and bearing, the magnetic field in the thrust bearing is no longer axisymmetric one, or the dynamic control current in the winding is time dependent one, eddy currents are caused to flow inside the conducting material, then the power losses are very important for magnetic bearing design. This paper presents an analytical model of a thrust magnetic bearing, and the magnetic fields, forces and losses of thrust magnetic bearing are calculated. In the calculations the frequency of dynamic control current is up to 1000Hz, rotating speed is from 60rpm to 1200rpm, and the non-linearity of material is also taken into consideration. The results shows that if the magnetic field is not saturation, the eddy losses is proportional to dynamic control current frequency and a square function of dynamic control current, and also 5/2 power function of shaft's speed.

  15. Hybrid Superconducting Magnetic Bearing (HSMB) for high-load devices

    Lifting capacities greater than 41 N/cm(exp 2) (60 psi) at 77 K have been achieved with a new type of levitation (hybrid) using a combination of permanent magnets and high quality melt-mixtured YBa2Cu3O(7-delta) (YBCO). The key concept of the hybrid superconducting magnetic bearing (HSMB) is the use of strong magnetic repulsion and attraction from permanent magnets for high levitation or suspension forces in conjunction with a superconductor's flux pinning characteristics to counteract the inherent instabilities in a system consisting of magnets only. To illustrate this concept, radial and axial forces between magnet/superconductor, magnet/magnet, and magnet/superconductor/magnet, were measured and compared for the thrust bearing configuration

  16. Approach to Synchronization Control of Magnetic Bearings Using Fuzzy Logic

    Yang, Li-Farn

    1996-01-01

    This paper presents a fuzzy-logic approach to the synthesis of synchronization control for magnetically suspended rotor system. The synchronization control enables a whirling rotor to undergo synchronous motion along the magnetic bearing axes; thereby avoiding the gyroscopic effect that degrade the stability of rotor systems when spinning at high speed. The control system features a fuzzy controller acting on the magnetic bearing device, in which the fuzzy inference system trained through fuzzy rules to minimize the differential errors between four bearing axes so that an error along one bearing axis can affect the overall control loop for the motion synchronization. Numerical simulations of synchronization control for the magnetically suspended rotor system are presented to show the effectiveness of the present approach.

  17. Modeling and Development of RMD Configuration Magnetic Bearing

    K.P. Lijesh

    2015-06-01

    Full Text Available The low load carrying capacity of Passive Magnetic Bearings (PMBs has restricted their use in many industrial applications. The Rotation Magnetized Direction (RMD configuration has emerged as a strong and viable method that is able to substantially enhance the load carrying capacity of passive magnetic bearings. It consists of both radially and axially polarized passive magnets. But the physical realization of a radially polarized magnet is difficult to achieve. In the present work, a RMD structure consisting of aluminum ring and cubical shaped magnets is proposed by developing the radially polarized magnets required for RMD structure. A theoretical model is derived by simulating the cuboid magnets in form of sector magnets by developing equivalent surface area. An experimental setup was designed and developed to conduct experimental verification. The theoretical model is validated by conducting experiments on RMD configuration magnetic bearing and axially magnetized full ring bearing. The comparison of the load carrying capacity by different configuration is performed and results are presented.

  18. Dynamic analysis of a magnetic bearing system with flux control

    Knight, Josiah; Walsh, Thomas; Virgin, Lawrence

    1994-01-01

    Using measured values of two-dimensional forces in a magnetic actuator, equations of motion for an active magnetic bearing are presented. The presence of geometric coupling between coordinate directions causes the equations of motion to be nonlinear. Two methods are used to examine the unbalance response of the system: simulation by direct integration in time; and determination of approximate steady state solutions by harmonic balance. For relatively large values of the derivative control coefficient, the system behaves in an essentially linear manner, but for lower values of this parameter, or for higher values of the coupling coefficient, the response shows a split of amplitudes in the two principal directions. This bifurcation is sensitive to initial conditions. The harmonic balance solution shows that the separation of amplitudes actually corresponds to a change in stability of multiple coexisting solutions.

  19. Rotor Vibration Reduction via Active Hybrid Bearings

    Nicoletti, Rodrigo; Santos, Ilmar

    2002-01-01

    The use of fluid power to reduce and control rotor vibration in rotating machines is investigated. An active hybrid bearing is studied, whose main objective is to reduce wear and vibration between rotating and stationary machinery parts. By injecting pressurised oil into the oil film, through...... orifices machined in the bearing pads, one can alter the machine dynamic characteristics, thus enhancing its operational range. A mathematical model of the rotor-bearing system, as well as of the hydraulic system, is presented. Numerical results of the system frequency response show good agreement with...

  20. On-line parameter estimation of a magnetic bearing

    Delpoux, Romain; Floquet, Thierry

    2011-01-01

    This article presents a parameter estimation algorithm for a magnetic bearing. Such process have strongly nonlinear dynamics andare inherently unstable systems. A simplified model of the magnetic bearing is developed in order to be able to estimate certain parameters. These parameters are difficult to measure, and may slightly vary over time. The expression of the estimates is written as a function of integrals of the inputs and outputs of the system. The experiments show a fast and robust on...

  1. An Integrated Magnetic Circuit Model and Finite Element Model Approach to Magnetic Bearing Design

    Provenza, Andrew J.; Kenny, Andrew; Palazzolo, Alan B.

    2003-01-01

    A code for designing magnetic bearings is described. The code generates curves from magnetic circuit equations relating important bearing performance parameters. Bearing parameters selected from the curves by a designer to meet the requirements of a particular application are input directly by the code into a three-dimensional finite element analysis preprocessor. This means that a three-dimensional computer model of the bearing being developed is immediately available for viewing. The finite element model solution can be used to show areas of magnetic saturation and make more accurate predictions of the bearing load capacity, current stiffness, position stiffness, and inductance than the magnetic circuit equations did at the start of the design process. In summary, the code combines one-dimensional and three-dimensional modeling methods for designing magnetic bearings.

  2. Magnetic bearings: A key technology for advanced rocket engines?

    Girault, J. PH.

    1992-01-01

    For several years, active magnetic bearings (AMB) have demonstrated their capabilities in many fields, from industrial compressors to control wheel suspension for spacecraft. Despite this broad area, no significant advance has been observed in rocket propulsion turbomachinery, where size, efficiency, and cost are crucial design criteria. To this respect, Societe Europeenne de Propulsion (SEP) had funded for several years significant efforts to delineate the advantages and drawbacks of AMB applied to rocket propulsion systems. Objectives of this work, relative technological basis, and improvements are described and illustrated by advanced turbopump layouts. Profiting from the advantages of compact design in cryogenic environments, the designs show considerable improvements in engine life, performances, and reliability. However, these conclusions should still be tempered by high recurrent costs, mainly due to the space-rated electronics. Development work focused on this point and evolution of electronics show the possibility to decrease production costs by an order of magnitude.

  3. CONTROL SYSTEM OF MAGNETIC BEARINGS BASED ON LINEAR QUADRATIC METHOD OF OPTIMAL CONTROL STRATEGY

    Zhu Huangqiu

    2005-01-01

    A state equation for radical 4-degree-of-freedom active magnetic bearings is built, and the approach on how to use linear quadratic method of optical control theory to design a centralized and decentralized parameters control system is introduced, and also Matlab language is used to simulate and analyze. The simulation results have proved that the differences are small between centralized parameters and decentralized parameters control system. The conclusions of experiments have shown that decentralized controllers designed from optimal state feedback theory meet the requirements of active magnetic bearing system. The vibration amplitude of the rotor is about 20 μm when the speed of the rotor runs between 0 to 60 000 r/min. This method may be used in the study and design of controllers of magnetic bearings.

  4. Sudden venting test of an emergency bearing for the magnet bearing type compound molecular pump

    The vacuum evacuation system for nuclear fusion reactors bears the role of exhausting hydrogen isotopes in large quantity together with helium continuously for long hours, and as the high vacuum pumps for this purpose, the mechanical pumps which can do continuous evacuation and decrease the quantity of staying radioactive tritium, such as turbo molecular pumps and compound molecular pumps, are promising. Because of the compatibility with tritium, oil lubrication is not desirable, accordingly, the pumps with ceramic rotating vanes and magnetic bearings are demanded. As a part of the development of a magnetic bearing type mechanical pump which can be used for nuclear fusion reactors, the compound molecular pump, in which emergency bearings were incorporated, was made for trial, and the test of sudden air intrusion was carried out, as the results, various knowledges were obtained. The constitution of the testing setup, and the test results are reported. When air was injected at the pressure rise of 3.3x104 Pa/s from exhaust port side, after about 2.5 s, the maximum lift of 4.2x103 N arose. When air was injected at the pressure rise of 2.7x105 Pa/s from the suction part side, after about 0.4s, the maximum lift of 6.9x103 N arose. In the air injection alternately from the suction port and exhaust port sides, the emergency bearings functioned normally in 10 times of the test. (K.I.)

  5. Development of a dc motor with virtually zero powered magnetic bearing

    1971-01-01

    The development of magnetic bearings for use in direct current electric motors is discussed. The characteristics of the magnets used in the construction of the bearings are described. A magnetic bearing using steel armoring on permanent magnets was selected for performance tests. The specifications of the motor are presented. The test equipment used in the evaluation is described.

  6. A spindle running on a five axes magnetic suspension based on conical bearings

    Carabelli, S.; Delprete, C.; Genta, G.; Moretto, I.

    1995-12-31

    The study and design of a small electric high-speed spindle based on two conical active magnetic bearings are described. The machine has been designed to simulate the rotor of a small turbo-compressor for the air conditioning unit of a small high performance aircraft. The two radial-axial bearings are controlled by a conventional five-axes decentralized compensator. The electromechanical components have been optimized for lightness and low cost. The unit here described constitutes an experimental rig for future studies in the field of magnetic suspension systems for high speed, small size rotating machinery.

  7. Rotational characteristics in the resonance state of the HTSC-permanent magnet hybrid magnetic bearing

    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.

  8. Single axis controlled hybrid magnetic bearing for left ventricular assist device: hybrid core and closed magnetic circuit.

    da Silva, Isaias; Horikawa, Oswaldo; Cardoso, Jose R; Camargo, Fernando A; Andrade, Aron J P; Bock, Eduardo G P

    2011-05-01

    In previous studies, we presented main strategies for suspending the rotor of a mixed-flow type (centrifugal and axial) ventricular assist device (VAD), originally presented by the Institute Dante Pazzanese of Cardiology (IDPC), Brazil. Magnetic suspension is achieved by the use of a magnetic bearing architecture in which the active control is executed in only one degree of freedom, in the axial direction of the rotor. Remaining degrees of freedom, excepting the rotation, are restricted only by the attraction force between pairs of permanent magnets. This study is part of a joint project in development by IDPC and Escola Politecnica of São Paulo University, Brazil. This article shows advances in that project, presenting two promising solutions for magnetic bearings. One solution uses hybrid cores as electromagnetic actuators, that is, cores that combine iron and permanent magnets. The other solution uses actuators, also of hybrid type, but with the magnetic circuit closed by an iron core. After preliminary analysis, a pump prototype has been developed for each solution and has been tested. For each prototype, a brushless DC motor has been developed as the rotor driver. Each solution was evaluated by in vitro experiments and guidelines are extracted for future improvements. Tests have shown good results and demonstrated that one solution is not isolated from the other. One complements the other for the development of a single-axis-controlled, hybrid-type magnetic bearing for a mixed-flow type VAD. PMID:21595710

  9. Electrostatic stabilizer for a passive magnetic bearing system

    Post, Richard F.

    2015-11-24

    Electrostatic stabilizers are provided for passive bearing systems composed of annular magnets having a net positive stiffness against radial displacements and that have a negative stiffness for vertical displacements, resulting in a vertical instability. Further embodiments are shown of a radial electrostatic stabilizer geometry (using circuitry similar to that employed in the vertical stabilizer). This version is suitable for stabilizing radial (lateral) displacements of a rotor that is levitated by annular permanent magnets that are stable against vertical displacements but are unstable against radial displacements.

  10. STUDY ON CATASTROPHIC MECHANISM FOR ROTOR DROP TRANSIENT VIBRATION FOLLOWING MAGNETIC BEARING FAILURE

    方之楚

    2002-01-01

    The nonlinear and transient vibration of a rotor, which dropped onto back-up bearings when its active magnetic bearings were out of order, was investigated. After strictly deriving its equations of motion and performing numerical simulations, the timehistories of rotating speed of the dropping rotor, and normal force at the rubbing contact point as well as the frequency spectrum of the vibration displacement of back-up bearings are fully analyzed. It is found that the strong and unsteady forced bending vibration of the unbalanced and damped rotor decelerating through its first bending vibtation of the unbalanced and damped rotor decelerating through its first critical speed as well as chattering at high frequencies caused by the nonlinearity at the rubbing contact point between the journal and back-up bearings may lead to the catastrophic damage of the system.

  11. Stability Limits of a PD Controller for a Flywheel Supported on Rigid Rotor and Magnetic Bearings

    Kascak, Albert F.; Brown, Gerald V.; Jansen, Ralph H.; Dever, TImothy P.

    2006-01-01

    Active magnetic bearings are used to provide a long-life, low-loss suspension of a high-speed flywheel rotor. This paper describes a modeling effort used to understand the stability boundaries of the PD controller used to control the active magnetic bearings on a high speed test rig. Limits of stability are described in terms of allowable stiffness and damping values which result in stable levitation of the nonrotating rig. Small signal stability limits for the system is defined as a nongrowth in vibration amplitude of a small disturbance. A simple mass-force model was analyzed. The force resulting from the magnetic bearing was linearized to include negative displacement stiffness and a current stiffness. The current stiffness was then used in a PD controller. The phase lag of the control loop was modeled by a simple time delay. The stability limits and the associated vibration frequencies were measured and compared to the theoretical values. The results show a region on stiffness versus damping plot that have the same qualitative tendencies as experimental measurements. The resulting stability model was then extended to a flywheel system. The rotor dynamics of the flywheel was modeled using a rigid rotor supported on magnetic bearings. The equations of motion were written for the center of mass and a small angle linearization of the rotations about the center of mass. The stability limits and the associated vibration frequencies were found as a function of nondimensional magnetic bearing stiffness and damping and nondimensional parameters of flywheel speed and time delay.

  12. Bear

    2005-01-01

    The famous physicist made for his scholars this riddle. A fellow encountered a bear in a wasteland. There was nobody else there. Both were frightened and ran away. Fellow to the north, bear to the west. Suddenly the fellow stopped, aimed his gun to the south and shot the bear. What colour was the bear?

  13. Fully Suspended, Five-Axis, Three-Magnetic-Bearing Dynamic Spin Rig With Forced Excitation

    Morrison, Carlos R.; Provenza, Andrew; Kurkov, Anatole; Montague, Gerald; Duffy, Kirsten; Mehmed, Oral; Johnson, Dexter; Jansen, Ralph

    2004-01-01

    The Five-Axis, Three-Magnetic-Bearing Dynamic Spin Rig, a significant advancement in the Dynamic Spin Rig (DSR), is used to perform vibration tests of turbomachinery blades and components under rotating and nonrotating conditions in a vacuum. The rig has as its critical components three magnetic bearings: two heteropolar radial active magnetic bearings and a magnetic thrust bearing. The bearing configuration allows full vertical rotor magnetic suspension along with a feed-forward control feature, which will enable the excitation of various natural blade modes in bladed disk test articles. The theoretical, mechanical, electrical, and electronic aspects of the rig are discussed. Also presented are the forced-excitation results of a fully levitated, rotating and nonrotating, unbladed rotor and a fully levitated, rotating and nonrotating, bladed rotor in which a pair of blades was arranged 180 degrees apart from each other. These tests include the bounce mode excitation of the rotor in which the rotor was excited at the blade natural frequency of 144 Hz. The rotor natural mode frequency of 355 Hz was discerned from the plot of acceleration versus frequency. For nonrotating blades, a blade-tip excitation amplitude of approximately 100 g/A was achieved at the first-bending critical (approximately 144 Hz) and at the first-torsional and second-bending blade modes. A blade-tip displacement of 70 mils was achieved at the first-bending critical by exciting the blades at a forced-excitation phase angle of 908 relative to the vertical plane containing the blades while simultaneously rotating the shaft at 3000 rpm.

  14. Preparation of Myeloid Derived Suppressor Cells (MDSC) from Naive and Pancreatic Tumor-bearing Mice using Flow Cytometry and Automated Magnetic Activated Cell Sorting (AutoMACS)

    Nelson, Nadine; Szekeres, Karoly; Cooper, Denise; Ghansah, Tomar

    2012-01-01

    MDSC are a heterogeneous population of immature macrophages, dendritic cells and granulocytes that accumulate in lymphoid organs in pathological conditions including parasitic infection, inflammation, traumatic stress, graft-versus-host disease, diabetes and cancer1-7. In mice, MDSC express Mac-1 (CD11b) and Gr-1 (Ly6G and Ly6C) surface antigens7. It is important to note that MDSC are well studied in various tumor-bearing hosts where they are significantly expanded and suppress anti-tumor imm...

  15. Development of magnetic bearing system for a new third-generation blood pump.

    Lee, Jung Joo; Ahn, Chi Bum; Choi, Jaesoon; Park, Jun Woo; Song, Seung-Joon; Sun, Kyung

    2011-11-01

    A magnetic bearing system is a crucial component in a third-generation blood pump, particularly when we consider aspects such as system durability and blood compatibility. Many factors such as efficiency, occupying volume, hemodynamic stability in the flow path, mechanical stability, and stiffness need to be considered for the use of a magnetic bearing system in a third-generation blood pump, and a number of studies have been conducted to develop novel magnetic bearing design for better handling of these factors. In this study, we developed and evaluated a new magnetic bearing system having a motor for a new third-generation blood pump. This magnetic bearing system consists of a magnetic levitation compartment and a brushless direct current (BLDC) motor compartment. The active-control degree of freedom is one; this control is used for controlling the levitation in the axial direction. The levitation in the radial direction has a passive magnetic levitation structure. In order to improve the system efficiency, we separated the magnetic circuit for axial levitation by using a magnetic circuit for motor drive. Each magnetic circuit in the bearing system was designed to have a minimum gap by placing mechanical parts, such as the impeller blades, outside the circuit. A custom-designed noncontact gap sensor was used for minimizing the system volume. We fabricated an experimental prototype of the proposed magnetic bearing system and evaluated its performance by a control system using the Matlab xPC Target system. The noncontact gap sensor was an eddy current gap sensor with an outer diameter of 2.38 mm, thickness of 0.88 mm, and resolution of 5 µm. The BLDC motor compartment was designed to have an outer diameter of 20 mm, length of 28.75 mm, and power of 4.5 W. It exhibited a torque of 8.6 mNm at 5000 rpm. The entire bearing system, including the motor and the sensor, had an outer diameter of 22 mm and a length of 97 mm. The prototype exhibited sufficient levitation

  16. Stability of multi orifice active tilting-pad journal bearings

    Haugaard, Asger M.; Santos, Ilmar

    2010-01-01

    The stability properties of actively lubricated tilting-pad journal bearings are investigated theoretically. The bearing preload factor and control system gains are varied, and stable and unstable regions are identified. It is seen, that the control system influences bearing stability, and that the...... nature and magnitude of this influence depends on the rotor mass, preload factor and rotational speed. Furthermore, it is shown that assuming the bearing pads to be rigid can produce a substantial error. A rigid pad model will overpredict the stable range of the bearing, thus it may lead to failure if...

  17. Influence of backup bearings and support structure dynamics on the behavior of rotors with active supports

    Flowers, George T.

    1995-01-01

    Progress made in the current year is listed, and the following papers are included in the appendix: Steady-State Dynamic Behavior of an Auxiliary Bearing Supported Rotor System; Dynamic Behavior of a Magnetic Bearing Supported Jet Engine Rotor with Auxiliary Bearings; Dynamic Modelling and Response Characteristics of a Magnetic Bearing Rotor System with Auxiliary Bearings; and Synchronous Dynamics of a Coupled Shaft/Bearing/Housing System with Auxiliary Support from a Clearance Bearing: Analysis and Experiment.

  18. Experimental investigations of active air bearings

    Santos, Ilmar; Morosi, Stefano

    2012-01-01

    greatest challenges in a high-speed gas bearing design. A great deal of research is devoted to attack such issues, where most propose passive designs such as compliant foil bearings, tilting pad and flexure pivot gas bearings. These solutions proved to be effective in improving static and dynamic......Along with traditional oil lubrication, increasing demand for high-speed applications has renewed attention to gas bearings technology. Traditional aerostatic and aerodynamic gas lubrication has been widely used in a variety of applications, ranging from high-speed spindles to micro and meso......-scale turbomachinery. The present paper deals with experimental rotordynamic testing of a flexible rotor supported by hybrid aerostaticaerodynamic gas journal bearing equipped with an electronic radial air injection system. From a rotordynamic point of view there are two phenomena that limit the widespread of...

  19. An Air Bearing Rotating Coil Magnetic Measurement System

    Gottschalk, Stephen C; Taylor, David J; Thayer, William

    2005-01-01

    This paper describes a rotating coil magnetic measurement system supported on air bearings. The design is optimized for measurements of 0.1micron magnetic centerline changes on long, small aperture quadrupoles. Graphite impregnated epoxy resin is used for the coil holder and coil winding forms. Coil holder diameter is 11 mm with a length between supports of 750mm. A pair of coils is used to permit quadrupole bucking during centerline measurements. Coil length is 616mm, inner radius 1.82mm, outer radius 4.74mm. The key features of the mechanical system are simplicity; air bearings for accurate, repeatable measurements without needing warm up time and a vibration isolated stand that uses a steel-topped Newport optical table with air suspension. Coil rotation is achieved by a low noise servo motor controlled by a standalone Ethernet servo board running custom servo software. Coil calibration procedures that correct wire placement errors, tests for mechanical resonances, and other system checks will also be discu...

  20. Mechanical Characteristics of a Thrust Magnetic Bearing%推力轴承的力学特性

    2000-01-01

    Static and dynamic mechanical characteristics of a thrustmagnetic bearing are studied owing to the inclination of the runner disk. The application refers to a thrust magnetic bearing for a turbo-expander/compressor. The static tilt of the runner disk has remarkable influence on the mechanical characteristics of thrust magnetic bearing, it can change the static load distribution between two radial magnetic bearings and will exert violent coupling effect among a thrust magnetic bearing and two radial magnetic bearings. Such a finding can be used for the coupled electromechanical dynamics analysis of rotor system equipped with magnetic bearings.

  1. Optimization of a Hybrid Magnetic Bearing for a Magnetically Levitated Blood Pump via 3-D FEA

    Cheng, Shanbao; Olles, Mark W.; Burger, Aaron F.; Steven W Day

    2011-01-01

    In order to improve the performance of a magnetically levitated (maglev) axial flow blood pump, three-dimensional (3-D) finite element analysis (FEA) was used to optimize the design of a hybrid magnetic bearing (HMB). Radial, axial, and current stiffness of multiple design variations of the HMB were calculated using a 3-D FEA package and verified by experimental results. As compared with the original design, the optimized HMB had twice the axial stiffness with the resulting increase of negati...

  2. Local Attitudes towards Bear Management after Illegal Feeding and Problem Bear Activity

    David Fraser

    2013-09-01

    Full Text Available The “pot bears” received international media attention in 2010 after police discovered the intentional feeding of over 20 black bears during the investigation of an alleged marijuana-growing operation in Christina Lake, British Columbia, Canada. A two-phase random digit dialing survey of the community was conducted in 2011 to understand local perspectives on bear policy and management, before and after a summer of problem bear activity and government interventions. Of the 159 households surveyed in February 2011, most had neutral or positive attitudes towards bears in general, and supported the initial decision to feed the food-conditioned bears until the autumn hibernation. In contrast to wildlife experts however, most participants supported relocating the problem bears, or allowing them to remain in the area, ahead of killing; in part this arose from notions of fairness despite the acknowledged problems of relocation. Most locals were aware of the years of feeding but did not report it, evidently failing to see it as a serious form of harm, even after many bears had been killed. This underscores the importance of preventive action on wildlife feeding and the need to narrow the gap between public and expert opinion on the likely effects of relocation versus killing.

  3. The role of superconductivity in magnetic bearings for high-load applications

    Downer, James; Eisenhaure, David

    1993-01-01

    Slewing of large payloads will require control torque and angular momentum storage capacities that are large in comparison to the capabilities of available control moment gyros (CMG's). SatCon Technology Corporation is currently designing a CMG which may be employed as a slew actuator for large spacecraft or other payloads. The slew actuator employs a type of magnetic bearing which may be used in high load applications. The magnetic bearing is also used to fully gimbal the suspended rotor of the slew actuator. The use of magnetic bearings in angular momentum exchange actuators has the primary advantage that physical contact between the rotor and stator is eliminated. This leads to greatly extended life, increased reliability, and reduced vibrations. Several actuators operating on magnetic bearings have been demonstrated in previous research efforts. These were sized for use in small satellites. For conventional magnetic bearings, which employ magnetic cores, high torsional loading may require that the magnetic structure be excessively massive. An alternative magnetic bearing design which employs a superconducting coil and eliminates conventional magnetic structures is discussed. The baseline approach is to replace the field coil of a conventional magnetic bearing with the superconducting coil.

  4. Computational Analysis of Static and Dynamic Behaviour of Magnetic Suspensions and Magnetic Bearings

    Britcher, Colin P. (Editor); Groom, Nelson J.

    1996-01-01

    Static modelling of magnetic bearings is often carried out using magnetic circuit theory. This theory cannot easily include nonlinear effects such as magnetic saturation or the fringing of flux in air-gaps. Modern computational tools are able to accurately model complex magnetic bearing geometries, provided some care is exercised. In magnetic suspension applications, the magnetic fields are highly three-dimensional and require computational tools for the solution of most problems of interest. The dynamics of a magnetic bearing or magnetic suspension system can be strongly affected by eddy currents. Eddy currents are present whenever a time-varying magnetic flux penetrates a conducting medium. The direction of flow of the eddy current is such as to reduce the rate-of-change of flux. Analytic solutions for eddy currents are available for some simplified geometries, but complex geometries must be solved by computation. It is only in recent years that such computations have been considered truly practical. At NASA Langley Research Center, state-of-the-art finite-element computer codes, 'OPERA', 'TOSCA' and 'ELEKTRA' have recently been installed and applied to the magnetostatic and eddy current problems. This paper reviews results of theoretical analyses which suggest general forms of mathematical models for eddy currents, together with computational results. A simplified circuit-based eddy current model proposed appears to predict the observed trends in the case of large eddy current circuits in conducting non-magnetic material. A much more difficult case is seen to be that of eddy currents in magnetic material, or in non-magnetic material at higher frequencies, due to the lower skin depths. Even here, the dissipative behavior has been shown to yield at least somewhat to linear modelling. Magnetostatic and eddy current computations have been carried out relating to the Annular Suspension and Pointing System, a prototype for a space payload pointing and vibration

  5. Experimental Grey Box Model Identification of an Active Gas Bearing

    Theisen, Lukas Roy Svane; Pierart Vásquez, Fabián Gonzalo; Niemann, Hans Henrik;

    2014-01-01

    Gas bearings have inherent dynamics that gives rise to low damping and potential instability at certain rotational speeds. Required damping and stabilization properties can be achieved by active ow control if bearing parameters are known. This paper deals with identifacation of parameters in a...... dynamic model of an active gas bearing and subsequent control loop design. A grey box model is determined based on experiments where piezo actuated valves are used to perturb the journal and hence excite the rotor-bearing system. Such modelling from actuator to output is shown to effciently support...... controller design, in contrast to impact models that focus on resonance dynamics. The identified model is able to accurately reproduce the lateral dynamics of the rotor-bearing system in a desired operating range, in this case around the first two natural frequencies. The identified models are validated and...

  6. Performance of a continuous flow ventricular assist device: magnetic bearing design, construction, and testing.

    Allaire, P; Hilton, E; Baloh, M; Maslen, E; Bearnson, G; Noh, D; Khanwilkar, P; Olsen, D

    1998-06-01

    A new centrifugal continuous flow ventricular assist device, the CFVAD III, which is fully magnetic bearing suspended, has been developed. It has only one moving part (the impeller), has no contact (magnetic suspension), is compact, and has minimal heating. A centrifugal impeller of 2 inch outer diameter is driven by a permanent magnet brushless DC motor. This paper discusses the design, construction, testing, and performance of the magnetic bearings in the unit. The magnetic suspension consists of an inlet side magnetic bearing and an outlet side magnetic bearing, each divided into 8 pole segments to control axial and radial displacements as well as angular displacements. The magnetic actuators are composed of several different materials to minimize size and weight while having sufficient load capacity to support the forces on the impeller. Flux levels in the range of 0.1 T are employed in the magnetic bearings. Self sensing electronic circuits (without physical sensors) are employed to determine the impellar position and provide the feedback control signal needed for the magnetic bearing control loops. The sensors provide position sensitivity of approximately 0.025 mm. A decentralized 5 axis controller has been developed using modal control techniques. Proportional integral derivative controls are used for each axis to levitate the magnetically supported impeller. PMID:9650668

  7. Schemes for applying active lubrication to main engine bearings

    Estupinan, Edgar Alberto; Santos, Ilmar

    2009-01-01

    The work presented here is a theoretical study that describes two different schemes for the oil injection system in actively lubricated main engine bearings. The use of active lubrication in journal bearings helps to enhance the hydrodynamic fluid film by increasing the fluid film thickness and...... orifices circumferentially located around the bearing surface. The pressure distribution of the hydrodynamic fluid film in journal bearings is governed by the Reynolds equation, which is modified to accommodate the dynamics of active lubrication, and which can be numerically solved using finite...... consequently reducing viscous friction losses and vibrations. One refers to active lubrication when conventional hydrodynamic lubrication is combined with dynamically modified hydrostatic lubrication. In this case, the hydrostatic lubrication is modified by injecting oil at controllable pressures, through...

  8. Development of superconducting magnetic bearing with superconducting coil and bulk superconductor for flywheel energy storage system

    Highlights: •We have proposed superconducting (SC) magnetic bearings using SC coil and bulks. •We manufactured a small scale test device based on our concept. •The device levitated a rotor without mechanical contact. •The rotor was rotated contactless over 2000 rpm. •We have demonstrated our SC magnetic bearing feasibility using the device. -- Abstract: We have been developing superconducting magnetic bearing for flywheel energy storage system to be applied to the railway system. The bearing consists of a superconducting coil as a stator and bulk superconductors as a rotor. A flywheel disk connected to the bulk superconductors is suspended contactless by superconducting magnetic bearings (SMBs). We have manufactured a small scale device equipped with the SMB. The flywheel was rotated contactless over 2000 rpm which was a frequency between its rigid body mode and elastic mode. The feasibility of this SMB structure was demonstrated

  9. Research on analytical model and design formulas of permanent magnetic bearings based on Halbach array with arbitrary segmented magnetized angle

    Wang, Nianxian; Wang, Dongxiong; Chen, Kuisheng; Wu, Huachun

    2016-07-01

    The bearing capacity of permanent magnetic bearings can be improved efficiently by using the Halbach array magnetization. However, the research on analytical model of Halbach array PMBs with arbitrary segmented magnetized angle has not been developed. The application of Halbach array PMBs has been limited by the absence of the analytical model and design formulas. In this research, the Halbach array PMBs with arbitrary segmented magnetized angle has been studied. The magnetization model of bearings is established. The magnetic field distribution model of the permanent magnet array is established by using the scalar magnetic potential model. On the basis of this, the bearing force model and the bearing stiffness model of the PMBs are established based on the virtual displacement method. The influence of the pair of magnetic rings in one cycle and the structure parameters of PMBs on the maximal bearing capacity and support stiffness characteristics are studied. The reference factors for the design process of PMBs have been given. Finally, the theoretical model and the conclusions are verified by the finite element analysis.

  10. Research of Digital Power Amplifier Simulation for High-power Blower with Active Magnetic Bearing%大功率磁悬浮鼓风机数字功放的仿真研究

    于文涛; 刘淑琴

    2011-01-01

    High-power blower with active magnetic bearing (AMB) has advantages of small, high speed, high reliability, low noise, it uses three-level digital switching power amplifier base on field programmable gate array (FPGA). Using Matlab/Simulink power system blackset library to complete the model of half-bridge circuit and current sensing circuit, simulate the FPGA internal data processing by embedded M-function modules.The simulation and experimental results verify the correctness of this method of modeling.It provides a new accurate method for simulation of digital circuit power amplifier.%大功率磁悬浮轴承鼓风机具有体积小、转速高、可靠性高、噪音低等优点,其功率放大器采用基于现场可编程门阵列(FPGA)的三电平PWM数字功放,应用Matlab/Simulink中基于电力系统模块集库,完成数字功放电路中的半桥电路和电流采样电路的建模,通过植入M函数文件内嵌功能模块模拟了FPGA内部的数据处理流程.仿真与实验结果验证了该建模方法的正确性,为数字电路功放的仿真提供了新的准确方法.

  11. 三相交流主动磁轴承参数设计与特性分析%Parameter Design and Characteristic Analysis for Three-Phase AC Active Magnetic Bearing

    诸德宏; 程新; 朱熀秋

    2009-01-01

    A mathematical model of the suspension forces is established for three-phase inverter-fed AC radial magnetic bearings. According to the requirement the suspension forces, parameters of an experimental prototype are calculated. The magnetic field and suspension forces of the rotor are verified using Ansoft. Nonlinearity of the suspension forces and the coupling characteristics of the movement between two degrees of freedom around the balance position are calculated and analyzed. The results show that the mechanical configuration and magnetic circuits of the magnetic bearing are correct, and the suspension magnetic forces satisfy the design requirement. Suspension forces have good linearity and symmetry around the balance position, and the movement of two degrees of freedom around balance position has no coupling.%建立了一种三相逆变器驱动的交流主动磁轴承的悬浮力数学模型,根据实验样机悬浮磁力的要求,给出了实验样机参数计算过程.利用Ansoft对该结构磁轴承的磁场和转子受力情况进行仿真验算,并对磁轴承悬浮力非线性和转子在平衡位置附近的运动耦合性进行了计算分析.研究结果表明:这种磁轴承机械和磁路结构合理,悬浮磁力满足设计要求,悬浮力在平衡位置附近具有较好的线性和对称性,二自由度运动几乎没有耦合.

  12. PARAMETER DESIGN AND FINITE ELEMENT ANALYSIS FOR RADIALAXIAL ACTIVE MAGNETIC BEARING WITH SHARING BIASED CURRENT%径向一轴向共用偏磁电流的主动磁轴承结构参数设计与有限元分析

    诸德宏; 卢立户; 刘海娟; 程新; 王鹏

    2011-01-01

    The configuration and working principle of a novel radial-axial active magnetic bearing with sharing biased magnetic current were introduced. The flux path was calculated by using the equivalent magnetic circuit, and the mathematical models of suspension forces were deduced. According to design desire of the suspension forces, the experiment prototype of the novel magnetic bearing was designed . The experiment prototype of the novel magnetic bearing' s flux path is analyzed by finite element Ansoft software. The results of theory analysis and finite element analysis have shown that the mechanical configuration and magnetic circuits of the magnetic bearing are reasonable, and the suspension forces are satisfied design desire, and the movement and magnetic circuits among 3 degrees of freedom around the balanceable position have almost no coupling, and using independent PID(proportion integration differentiation) control among 3 degrees of freedom for this novel magnetic bearing and greatly simplifying the control system.%介绍一种新型径向一轴向共用偏磁电流的主动磁轴承的基本结构和工作机理,用等效磁路法对该磁轴承的磁路进行计算,得到悬浮力数学模型;根据悬浮力要求设计实验样机参数,利用有限元Ansoft软件对磁轴承样机的磁路进行有限元分析.理论研究和有限元分析结果表明,该磁轴承机械和磁路结构合理,悬浮力满足设计要求,各自由度在平衡位置附近运动,与磁路没有耦合,对各自由度可采用分散的PID(proportion integration differentiation)对其进行控制,大大简化控制系统.

  13. Design and implementation of an active rectangular aerostatic thrust bearing stage with electromagnetic actuators

    MAO JunHong; LI LiChuan

    2009-01-01

    The design and implementation of an active rectangular aerostaUc thrust bearing stage with electro-magnetic actuators are presented. The stage is fundamentally precise and simple since the out-of-plane degree-of-freedoms (DOF) of a thrust air bearing are closed-loop controlled by electromagnetic actua-tors. The design is one-moving-part with mechanical symmetry, and a commercially available air bear-ing is rigidly attached to the table. The actuators are four independent coils mounted to the guiding surface of the table with iron cores, which are directly machined on the table. A bench level prototype system is developed and out-of-plane axes decoupled models of the system are derived. A control al-gorithm synthesized by arbitrarily placing closed-loop poles according to the model with air bearing dynamics neglected is implemented by C programming language running on the DOS platform. The stage is capable of vertical direction precision micro-positioning and guiding 3-DOF plane motions without limiting the working range of plane motions. Positioning accuracy of the stage no longer de-pends upon design and manufacturing of an air bearing, while passive preload of the stage for a flat film aerostatic thrust bearing is eliminated.

  14. A magnetic bearing based on eddy-current repulsion

    Nikolajsen, J. L.

    1987-01-01

    This paper describes a new type of electromagnetic bearing, called the Eddy-Current Bearing, which works by repulsion between fixed AC-electromagnets and a conducting rotor. The following advantages are expected: inherent stability, higher load carrying capacity than DC-electromagnetic bearings, simultaneous radial, angular and thrust support, motoring and generating capability, and backup mode of operation in case of primary power failure. A prototype is under construction.

  15. A permanent-magnet rotor for a high-temperature superconducting bearing

    Mulcahy, T.M.; Hull, J.R.; Uherka, K.L. [Argonne National Lab., IL (United States); Abboud, R.G. [Commonwealth Research Corp., Chicago, IL (United States); Wise, J.H.; Carnegie, D.W. [Pennsylvania State Univ., University Park, PA (United States). Engineering Science

    1995-07-01

    Design, fabrication, and performance, of a 1/3-m dia., 10-kg flywheel rotor with only one bearing is discussed. To achieve low-loss energy storage, the rotor`s segmented-ring permanent-magnet (PM) is optimized for levitation and circumferential homogeneity. The magnet`s carbon composite bands enable practical energy storage.

  16. PRINCIPLES AND PARAMETER DESIGN FOR AC-DC THREE-DEGREE FREEDOM HYBRID MAGNETIC BEARINGS

    ZHU Huangqiu; XIE Zhiyi; ZHU Dehong

    2006-01-01

    To simplify the mechanical structure, decrease the overall system size of the 3-degree freedom axial-radial magnetic bearings and reduce the manufacturing costs as well as operating costs,an innovated AC-DC 3-degree freedom hybrid magnetic bearing is proposed, which is driven by a DC amplifier in axial direction and a 3-phase power converter in radial directions respectively, and the axial and radial bias magnetic fluxes are provided with a common radial polarized permanent magnet ring. The principle producing magnetic suspension forces is introduced. By using equivalent magnetic circuit method, the calculation formulas of magnetic suspension forces and the mathematics models of the system are deduced. Nonlinearities of suspension forces and cross coupling between different degree freedoms are studied further by calculating the suspension forces at different displacements and control currents to validate the feasibility of the mathematics model. Then based on the mathematics models of the bearing, a control method of this novel bearing is designed. Lastly, the methods on parameter design and calculations of the bearing are presented, and an applicable prototype is simulated to analyze the magnetic path by using finite element analysis. The theory analysis and simulation results have shown that this magnetic bearing incorporates the merits of 3-phase AC drive, permanent magnet flux biased and axial-radial combined control, and reduces overall system size and has higher efficiency and lower cost. This innovated magnetic bearing has a wide application in super-speed and super-precision numerical control machine tools, bearingless motors, high-speed flywheels, satellites, etc.

  17. A novel permanent magnetic bearing and its anti-wear effect in impeller total artificial heart

    2003-01-01

    A novel permanent magnetic bearing has been developed, which consists of two magnetic rings with different dimensions in the same direction of axial magnetization, located concentrically. Because of the effect of magnetic field, the magnetic rings keep a distance axially from each other. If the distance between the two rings changes, a rehabilitation force is produced to return to the original position. When this distance decreases, a repelling force will be generated; its component in axial direction can be used as a magnetic spring and its radial component can function as a bearing. With this novel permanent magnetic bearing, an impeller total artificial heart (TAH) is designed, manufactured and tested. The rotation is driven radially. On the left and right sides of the rotor magnets, two small magnetic rings are fixed onto the rotor, coupling with two big magnetic rings on both sides of the motor coil, to form the magnetic bearings. Hereby the bearings are used for wear reduction rather than rotor levitation. That means the magnetic bearings counteract the attractive force between the motor coil iron and rotor magnets so as to reduce the friction between the motor stator and rotor. At the left and right ends of the rotor, two impellers with the same width but different diameters are mounted. Thus the device has only one moving part-rotor; both the left pump and the right pump eject the blood synchronically; the volume equilibrium of both pumps can be achieved automatically without need of control. The device weighing 250 g has a length of 60 mm and a diameter of 40 mm at its largest point, and can produce a blood flow up to 150 mm Hg and 6 L/min from left pump, 50 mm Hg and 6 L/min from right pump, at rotating speed of 4000 r/min of the motor. The consumed power is under 10 W.

  18. Pneumatic locking device for magnetic bearing reaction wheel

    Privat, Michel; da Costa, Arlindo

    2003-09-01

    Due to the launch vibration environment, the use of locking device is necessary for large or heavy mechanisms. This remark is true in particular for the inertial actuators like magnetic bearing reaction wheels. These actuators have a rotor that is in magnetic levitation without any contact with the stator. Locking device is mandatory to maintain the rotor during the launch vibrations. To avoid contact between rotor and stator during the functional phase, the link created by the locking device must be completely released. This article presents a pneumatic locking device with pyrotechnical sub-systems that have been realised by "ALCATEL Space Industries" for the reaction wheels development in the frame of a CNES satellites family. The first paragraph presents the wheel functioning and briefly describes the Electro-mechanical components of the reaction wheel. The second paragraph describes a device based on a metallic bellows ring. A nitrogen pressure in the ring allows pushing the rotor against the stator. The rotor release is obtained by drilling the system tubing with a pyrotechnic valve. The third point describes the qualification tests and the resulting data. Some functional tests are made in warm and cold case with the locking device in order to improve some mechanical characteristics including the locking effort generated and the leakage rate. Launch vibrations and thermal tests have been realised and the good functioning of the mechanism is proven. At the end of these tests, the qualification has been pronounced. The device is now implemented within the reaction wheel. This equipment should flight in 2004. The next paragraph presents the works realised under CNES Research and Technology contract. The objectives were the characterisation of metallic bellows and some technological studies to improve the knowledge of the mechanical and functional characteristics of these elements. The first study was to create a Finite Element model of a bellow in order to

  19. Development of an Anti-Vibration Controller for Magnetic Bearing Cooling Systems Project

    National Aeronautics and Space Administration — This proposal outlines a program to develop a vibration-free reverse-Brayton cycle cooling system using specially-tuned magnetic bearings. Such a system is critical...

  20. Method for obtaining large levitation pressure in superconducting magnetic bearings

    Hull, John R.

    1996-01-01

    A method and apparatus for compressing magnetic flux to achieve high levitation pressures. Magnetic flux produced by a magnetic flux source travels through a gap between two high temperature superconducting material structures. The gap has a varying cross-sectional area to compress the magnetic flux, providing an increased magnetic field and correspondingly increased levitation force in the gap.

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

    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.

  2. Dynamical analysis of a flywheel-superconducting bearing with a moving magnet support

    A lateral stiffness improvement approach based on a moving magnet support is developed to reduce the vibration of a flywheel rotor-high temperature superconductor (HTS) bearing. A flywheel rotor levitated with an HTS bearing is modelled and then analysed with a moving stator magnet placed above the rotor. A dynamic support principle is introduced based on moving the stator magnet in anti-phase with the rotor displacement for small variations. A complete dynamical equation of the flywheel rotor is derived including gyroscopic and imbalance effects. The simulation results showed that the dynamic support of the flywheel rotor with additional stator magnet movements decreases the vibration of the flywheel rotor considerably

  3. Detail vibration analysis of magnetic bearing helium fan in high temperature reactor

    Since the pure helium environment inside the reactor, active magnetic bearing (AMB) is considered to be the best for the helium fan supported. Using AMB in such an important place, the coming problem must be solved is to know the detail rotor dynamics and vibration issue of it while the rotor length has been increased and the bearing stiffness been decreased. As most of conventional mechanical machine, this issue has to be well studied during the design stage. If the helium fan could run on 10% away from the critical speed, the risk of unexpected vibration will be well avoided, and it can fit for all the requirements as well. Better understanding of the vibration character of the helium fan rotor can help the engineer to optimum their design, not only for the rotor, but also for the active magnetic bearing. In this paper, several analyses, including modal shape, eigenfrequency, force response and gyroscopic effect influence of this helium fan rotor are processed by finite element method. On the finite element model, the helium fan is assumed to be an equal mass and equal diameter flywheel, and the elastic levitation of AMB is assumed as spring. Through some other reasonable simplifications, and some boundary condition assumptions, the analysis is processed well, and the results show the preliminary design helium fan suspended by AMB could safety run under the operating speed, even considering the gyroscopic effect. This analysis also makes us know this helium fan rotor better than before. The finite element analysis is finished by software ANSYS 8.0. (authors)

  4. Mycosynthesis of silver nanoparticles bearing antibacterial activity.

    Azmath, Pasha; Baker, Syed; Rakshith, Devaraju; Satish, Sreedharamurthy

    2016-03-01

    Mycosynthesis of silver nanoparticles was achieved by endophytic Colletotrichum sp. ALF2-6 inhabiting Andrographis paniculata. Well dispersed nanoparticles were characterized using UV-Visible spectrometry with maximum absorption conferring at 420 nm. FTIR analysis revealed possible biomolecules reducing the metal salt and stabilization of nanoparticles. XRD analysis depicted the diffraction intensities exhibiting between 20 and 80 °C at 2theta angle thus conferring the crystalline nature of nanoparticles. Morphological characteristic using TEM revealed the polydispersity of nanoparticles with size ranging from 20 to 50 nm. Synthesized nanoparticles exhibited bactericidal activity against selected human pathogens. Nanoparticles mode of action was carried out to reveal DNA damage activity. Thus the present investigation reports facile fabrication of silver nanoparticles from endophytic fungi. PMID:27013906

  5. Design and parameter estimation of hybrid magnetic bearings for blood pump applications

    Lim, Tau Meng; Zhang, Dongsheng; Yang, Juanjuan; Cheng, Shanbao; Low, Sze Hsien; Chua, Leok Poh; Wu, Xiaowei

    2009-10-01

    This paper discusses the design and parameter estimation of the dynamics characteristics of a high-speed hybrid magnetic bearings (HMBs) system for axial flow blood pump applications. The rotor/impeller of the pump is driven by a three-phase permanent magnet (PM) brushless and sensorless DC motor. It is levitated by two HMBs at both ends in five-degree-of-freedom with proportional-integral-derivative (PID) controllers; among which four radial directions are actively controlled and one axial direction is passively controlled. Test results show that the rotor can be stably supported to speeds of 14,000 rpm. The frequency domain parameter estimation technique with statistical analysis is adopted to validate the stiffness and damping coefficients of the HMBs system. A specially designed test rig facilitated the estimation of the bearing's coefficients in air—in both the radial and axial directions. The radial stiffness of the HMBs is compared to the Ansoft's Maxwell 2D/3D finite element magnetostatic results. Experimental estimation showed that the dynamics characteristics of the HMBs system are dominated by the frequency-dependent stiffness coefficients. The actuator gain was also successfully calibrated and may potentially extend the parameter estimation technique developed in the study of identification and monitoring of the pump's dynamics properties under normal operating conditions with fluid.

  6. Active Vibration Reduction Of Rigid Rotor Supported By Journal Bearings

    Ondrouch, Jan; Ferfecki, Petr; Poruba, Z.

    Gliwice: Politechnika Slaska, 2009, s. 85-90. ISBN 978-83-60102-52-7. [International Seminar of Applied Mechanics /13./. Wisla (PL), 29.05.2009-31.05.2009] Institutional research plan: CEZ:AV0Z20760514 Keywords : rotor system * hydrodynamic bearing * active vibration reduction Subject RIV: JR - Other Machinery

  7. Pressure instability of magnetic susceptibility of pyrrhotite bearing rocks from the KTB borehole

    Kapička, Aleš; Hoffmann, V.; Petrovský, Eduard

    2003-01-01

    Roč. 47, č. 2 (2003), s. 381-391. ISSN 0039-3169 Institutional research plan: CEZ:AV0Z3012916 Keywords : magnetic susceptibility * pressure treatment * pyrrhotite -bearing rocks Subject RIV: DE - Earth Magnetism, Geodesy, Geography Impact factor: 0.426, year: 2003

  8. Dynamic behavior of a magnetic bearing supported jet engine rotor with auxiliary bearings

    Flowers, George T.; Xie, Huajun; Sinha, S. C.

    1995-01-01

    This paper presents a study of the dynamic behavior of a rotor system supported by auxiliary bearings. The steady-state behavior of a simulation model based upon a production jet engine is explored over a wide range of operating conditions for varying rotor imbalance, support stiffness, and damping. Interesting dynamical phenomena, such as chaos, subharmonic responses, and double-valued responses, are presented and discussed.

  9. 3Dwheel: 3-axis low-noise, high-bandwidth attitude actuation from a single momentum wheel using magnetic bearings.

    Seddon, Jon; Pechev, Alexandre

    2009-01-01

    This paper proposes a new concept for attitude actuation for small satellites that uses active magnetic bearings to support and tilt a spinning rotor to provide 3-axis attitude control of the satellite using a single actuator. A controlled 3D motion in the spinning rotor provides a conventional torque output about the momentum axis and a gyroscopic torque output about any direction in the plane normal to the spinning axis. Therefore, a single tilting momentum-wheel can generate torque along t...

  10. Mechanical characterization of journal superconducting magnetic bearings: stiffness, hysteresis and force relaxation

    Superconducting magnetic bearings (SMBs) can provide stable levitation without direct contact between them and a magnetic source (typically a permanent magnet). In this context, superconducting magnetic levitation provides a new tool for mechanical engineers to design non-contact mechanisms solving the tribological problems associated with contact at very low temperatures. In the last years, different mechanisms have been proposed taking advantage of superconducting magnetic levitation. Flywheels, conveyors or mechanisms for high-precision positioning. In this work the mechanical stiffness of a journal SMBs have been experimentally studied. Both radial and axial stiffness have been considered. The influence of the size and shape of the permanent magnets (PM), the size and shape of the HTS, the polarization and poles configuration of PMs of the journal SMB have been studied experimentally. Additionally, in this work hysteresis behavior and force relaxation are considered because they are essential for mechanical engineer when designing bearings that hold levitating axles.

  11. Research on a novel high stiffness axial passive magnetic bearing for DGMSCMG

    Sun, Jinji; Wang, Chun'e.; Le, Yun

    2016-08-01

    To increase the displacement stiffness and decrease power loss of double gimbals magnetically suspended control momentum gyro (DGMSCMG), this paper researches a new structure of axial passive magnetic bearing (APMB). Different from the existing APMB, the proposed APMB is composed of segmented permanent magnets and magnetic rings. The displacement stiffness and angular stiffness expressions are derived by equivalent magnetic circuit method and infinitesimal method based on the end magnetic flux. The relationships are analyzed between stiffness and structure parameters such as length of air gap, length of permanent magnet, height of permanent magnet and end length of magnetic ring. Besides, the axial displacement stiffness measurement method of the APMB is proposed, and it verified the correctness of proposed theoretical method. The DGMSCMG prototype is manufactured and the slow-down characteristic experiment is carried out, and the experimental result reflects the low power loss feature of the APMB.

  12. A hydrodynamically suspended, magnetically sealed mechanically noncontact axial flow blood pump: design of a hydrodynamic bearing.

    Mitamura, Yoshinori; Kido, Kazuyuki; Yano, Tetsuya; Sakota, Daisuke; Yambe, Tomoyuki; Sekine, Kazumitsu; OKamoto, Eiji

    2007-03-01

    To overcome the drive shaft seal and bearing problem in rotary blood pumps, a hydrodynamic bearing, a magnetic fluid seal, and a brushless direct current (DC) motor were employed in an axial flow pump. This enabled contact-free rotation of the impeller without material wear. The axial flow pump consisted of a brushless DC motor, an impeller, and a guide vane. The motor rotor was directly connected to the impeller by a motor shaft. A hydrodynamic bearing was installed on the motor shaft. The motor and the hydrodynamic bearing were housed in a cylindrical casing and were waterproofed by a magnetic fluid seal, a mechanically noncontact seal. Impeller shaft displacement was measured using a laser sensor. Axial and radial displacements of the shaft were only a few micrometers for motor speed up to 8500 rpm. The shaft did not make contact with the bearing housing. A flow of 5 L/min was obtained at 8000 rpm at a pressure difference of 100 mm Hg. In conclusion, the axial flow blood pump consisting of a hydrodynamic bearing, a magnetic fluid seal, and a brushless DC motor provided contact-free rotation of the impeller without material wear. PMID:17343698

  13. Active Vibration Control of Rotor-Bearing Systems

    Blanco-Ortega, Andres; Silva-Navaro, Gerardo; Beltran-Carbajal, Francisco; Vela-Valdes, Luis Gerardo

    2010-01-01

    The active vibration control of a Jeffcott-like rotor through dynamic stiffness control and acceleration scheduling is addressed. The control approach consists of a servomechanism able to move one of the supporting bearings in such a way that the effective rotor length is controlled. As a consequence, the rotor stiffness and natural frequency are modified according to an off-line and smooth trajectory planning of the rotor speed/acceleration in order to reduce the unbalance response when pass...

  14. A flywheel energy storage system with permanent magnet bearing; Ein Schwungrad-Energiespeicher mit permanentmagnetischer Lagerung

    Kolk, M.

    1997-12-01

    It is the major objective of the work reported to expand the applications of radially passive permanent magnet bearings for rotors with increased mass and moment of inertia, and to show that partially passive magnetic bearings can be used for systems with high-capacity motors and generators. The following main aspects are discussed and explained: The fundamental principles and applications of flywheels; applicable magnetic bearing systems and their components; dynamic properties of a magnetically suspended rotor; design of the motor/generator unit of a flywheel system; the entire design of the prototype system developed and its essential components; safety aspects of the flywheel; power losses and power output; current applications and possible further applications of magnetically suspended flywheels; results and applications of permanent magnet bearings. (orig./CB) [Deutsch] Ein wesentliches Ziel dieser Arbeit ist, den Einsatzbereich fuer radial passive permanentmagnetische Lager fuer Rotoren mit groesserer Masse und groesserem Traegheitsmoment zu erweitern und zu zeigen, dass partiell passive Magnetlager sich auch fuer grosse Motor- und Generatorleistungen eignen. Auf folgende Schwerpunkte wird eingegangen: die Technik und die Verwendung von Schwungraedern, verschiedene Arten der Magnetlagerung und deren Komponenten, Dynamik eines magnetgelagerten Rotors, Auslegung des Motor/Generators eines Schwungradsystems, Gesamtaufbau des realisierten Prototypen und seine wesentlichen Baugruppen, Sicherheitsaspekte des Schwungrades, Verluste und Leistungsabgabe, Anwendungen und Erweiterungen des magnetgelagerten Schwungrades, Ergebnisse und Einsatzmoeglichkeiten permanentmagnetischer Lager. (orig./GL)

  15. DESIGN AND APPLICATION OF MAGNETIC BEARING SUSPENSION SYSTEM IN A THREE PHASE INDUCTION MOTOR

    Osman GÜRDAL

    1998-03-01

    Full Text Available The current popularity of suspension and levitation stems no doubt the possibilities in high-speed ground transportation schemes. Although these are both challenging and exciting, there is considerable scope for application of suspension techniques to achieving frictionless bearing. The requirement in this case is often for close tolerances, low power consumption, small airgaps and ingeneral, compactness. Thus, magnetic suspension using DC electromagnets schemes have received more attention than the other techniques of repulsion levitation. Proposed prototype system consists of a conventional stator and its rotor without iron core, set of electromagnets for suspension of rotor shaft and set of compensation circuits feedbacked by optical-transducers. Prototyped system is aimed as a laboratory demonstration tool so there is no challenging to exceed the speeds of 1500 rev/min that is the speed of motor with mechanical bearings. Magnetic bearing suspension system provides a high impact visual demonstration of many principles in undergraduate educational programs in electrical education, e.g., electromagnetic design, PD controlled compensation of a unstable control system and power amplifier design. The system is capable of giving a good comparison between mechanical and magnetic bearing up to speeds 350 rev/min. Power losses without load show about 15% reduction with magnetic bearing. The noise of the motor is also decreased to a low level.

  16. Effect of the repulsive force in the HTSC-permanent magnet hybrid bearing system

    Magnetic levitation using the pinning force of the YBaCuO high-Tc 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.

  17. A feasibility assessment of magnetic bearings for free-piston Stirling space power converters

    This report describes work performed by Mechanical Technology Incorporated (MTI) under NASA Contract NAS3-26061, open-quotes A Feasibility Assessment of Magnetic Bearings for Free-Piston Stirling Space Engines.close quotes The work was performed over the period from July 1990 through August 1991. The objective of the effort was to assess the feasibility and efficacy of applying magnetic bearings to free-piston Stirling-cycle power conversion machinery of the type currently being evaluated for possible use in future long-term space missions

  18. Centrifugally activated bearing for high-speed rotating machinery

    Post, Richard F.

    1994-01-01

    A centrifugally activated bearing is disclosed. The bearing includes an annular member that extends laterally and radially from a central axis. A rotating member that rotates about the central axis relative to the annular member is also included. The rotating member has an interior chamber that surrounds the central axis and in which the annular member is suspended. Furthermore, the interior chamber has a concave shape for retaining a lubricant therein while the rotating member is at rest and for retaining a lubricant therein while the rotating member is rotating. The concave shape is such that while the rotating member is rotating a centrifugal force causes a lubricant to be forced away from the central axis to form a cylindrical surface having an axis collinear with the central axis. This centrifugally displaced lubricant provides restoring forces to counteract lateral displacement during operation.

  19. Parameter estimation and actuator characteristics of hybrid magnetic bearings for axial flow blood pump applications.

    Lim, Tau Meng; Cheng, Shanbao; Chua, Leok Poh

    2009-07-01

    Axial flow blood pumps are generally smaller as compared to centrifugal pumps. This is very beneficial because they can provide better anatomical fit in the chest cavity, as well as lower the risk of infection. This article discusses the design, levitated responses, and parameter estimation of the dynamic characteristics of a compact hybrid magnetic bearing (HMB) system for axial flow blood pump applications. The rotor/impeller of the pump is driven by a three-phase permanent magnet brushless and sensorless motor. It is levitated by two HMBs at both ends in five degree of freedom with proportional-integral-derivative controllers, among which four radial directions are actively controlled and one axial direction is passively controlled. The frequency domain parameter estimation technique with statistical analysis is adopted to validate the stiffness and damping coefficients of the HMB system. A specially designed test rig facilitated the estimation of the bearing's coefficients in air-in both the radial and axial directions. Experimental estimation showed that the dynamic characteristics of the HMB system are dominated by the frequency-dependent stiffness coefficients. By injecting a multifrequency excitation force signal onto the rotor through the HMBs, it is noticed in the experimental results the maximum displacement linear operating range is 20% of the static eccentricity with respect to the rotor and stator gap clearance. The actuator gain was also successfully calibrated and may potentially extend the parameter estimation technique developed in the study of identification and monitoring of the pump's dynamic properties under normal operating conditions with fluid. PMID:19566728

  20. Effect of Active Mineral on Load-Bearing Autoclaved Aerocrete

    彭苏萍; 王立刚

    2001-01-01

    Influence of ultrafine active mineral (DK mineral) on mechanical property of fly ash based load-bearing aerocrete was analyzed. The result shows that the addition of DK mineral in a suitable amount can enhance obviously the compressive strength of aerocrete. According to the SEM-EDS and X-ray diffraction analyses, the crystal shapes of hydration products are well developed and interlocked for samples containing DK mineral. Its microstructure is denser than that of the samples without DK mineral. Having a good activation, the DK mineral makes both the type and the quantity of hydrated products be obviously superior to that of the contrast sample.

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

    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.

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

    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-Tc 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

  3. GA-BASED PID NEURAL NETVVORK CONTROL FOR MAGNETIC BEARING SYSTEMS

    LI Guodong; ZHANG Qingchun; LIANG Yingchun

    2007-01-01

    In order to overcome the system non-linearity and uncertainty inherent in magnetic bearing systems, a GA(genetic algorithm)-based PID neural network controller is designed and trained to emulate the operation of a complete system (magnetic beating, controller, and power amplifiers).The feasibility of using a neural network to control nonlinear magnetic beating systems with unknown dynamics is demonstrated. The key concept of the control scheme is to use GA to evaluate the candidate solutions (chromosomes), increase the generalization ability of PID neural network and avoid suffering from the local minima problem in network learning due to the use of gradient descent learning method. The simulation results show that the proposed architecture provides well robust performance and better reinforcement learning capability in controlling magnetic bearing systems.

  4. Optimization of the Superconducting Linear Magnetic Bearing of a Maglev Vehicle

    Quéval, Loïc; Sotelo, Guilherme G.; Kharmiz, Yassin; Dias, Daniel H. N.; Sass, Felipe; Zermeño, Víctor M. R; Gottkehaskamp, Raimund

    2015-01-01

    Considering the need for cost/performance prediction and optimization of superconducting maglev vehicles, we develop and validate here a 3D finite element model to simulate superconducting linear magnetic bearings. Then we reduce the 3D model to a 2D model in order to decrease the computing time. This allows us to perform in a reasonable time a stochastic optimization considering the superconductor properties and the vehicle operation. We look for the permanent magnet guideway geometry that m...

  5. Passive magnetic bearing in the 3rd generation miniature axial flow pump-the valvo pump 2.

    Okamoto, Eiji; Ishida, Yuya; Yano, Tetsuya; Mitamura, Yoshinori

    2015-06-01

    The new miniature axial flow pump (valvo pump 2) that is installed at the base of the ascending aorta consists of a six-phase stator, an impeller in which four neodymium magnets are incorporated, and passive magnetic bearings that suspend the impeller for axial levitation. The impeller is sustained by hydrodynamic force between the blade tip of the impeller and the inner housing of the stator. The passive magnetic bearing consists of a ring neodymium magnet and a columnar neodymium magnet. The ring neodymium magnet is set in the stationary side and the columnar neodymium magnet is incorporated in the impeller shaft. Both neodymium magnets are coaxially mounted, and the anterior and posterior passive magnetic bearings suspend the impeller by repulsion force against the hydrodynamic force that acts to move the impeller in the inflow port direction. The passive magnetic bearing was evaluated by a tensile test, and the levitation force of 8.5 N and stiffness of 2.45 N/mm was obtained. Performance of the axial flow pump was evaluated by an in vitro experiment. The passive magnetic bearing showed sufficient levitation capacity to suspend the impeller in an axial direction. In conclusion, the passive magnetic bearing is promising to be one of levitation technology for the third-generation axial flow blood pump. PMID:25407124

  6. A new eddy current model for magnetic bearing control system design

    Feeley, Joseph J.; Ahlstrom, Daniel J.

    1992-01-01

    This paper describes a new VLSI-based controller for the implementation of a Linear-Quadratic-Gaussian (LQG) theory-based control system. Use of the controller is demonstrated by design of a controller for a magnetic bearing and its performance is evaluated by computer simulation.

  7. Stellar magnetic activity

    The stellar emission in the chromospheric Ca II H+K lines is compared with the coronal soft X-ray emission, measuring the effects of non-radiative heating in the outer atmosphere at temperatures differing two orders of magnitude. The comparison of stellar flux densities in Ca II H+K and X-rays is extended to fluxes from the transition-region and the high-temperature chromosphere. The stellar magnetic field is probably generated in the differentially rotating convective envelope. The relation between rotation rate and the stellar level of activity measured in chromospheric, transition-region, and coronal radiative diagnostics is discovered. X-ray observations of the binary λ Andromedae are discussed. The departure of M-type dwarfs from the main relations, and the implications for the structure of the chromospheres of these stars are discussed. Variations of the average surface flux densities of the Sun during the 11-year activity cycle agree with flux-flux relations derived for other cool stars, suggesting that the interpretation of the stellar relations may be furthered by studying the solar analogue in more detail. (Auth.)

  8. Ambient-Temperature Passive Magnetic Bearings for Flywheel Energy Storage Systems

    Bender, D.; Post, R.

    2000-05-26

    Based on prior work at the Lawrence Livermore National Laboratory ambient-temperature passive magnetic bearings are being adapted for use in high-power flywheel energy storage systems developed at the Trinity Flywheel Power company. En route to this goal specialized test stands have been built and computer codes have been written to aid in the development of the component parts of these bearing systems. The Livermore passive magnetic bearing system involves three types of elements, as follows: (1) Axially symmetric levitation elements, energized by permanent magnets., (2) electrodynamic ''stabilizers'' employing axially symmetric arrays of permanent magnet bars (''Halbach arrays'') on the rotating system, interacting with specially wound electrically shorted stator circuits, and, (3) eddy-current-type vibration dampers, employing axially symmetric rotating pole assemblies interacting with stationary metallic discs. The theory of the Livermore passive magnetic bearing concept describes specific quantitative stability criteria. The satisfaction of these criteria will insure that, when rotating above a low critical speed, a bearing system made up of the three elements described above will be dynamically stable. That is, it will not only be stable for small displacements from equilibrium (''Earnshaw-stable''), but will also be stable against whirl-type instabilities of the types that can arise from displacement-dependent drag forces, or from mechanical-hysteritic losses that may occur in the rotor. Our design problem thus becomes one of calculating and/or measuring the relevant stiffnesses and drag coefficients of the various elements and comparing our results with the theory so as to assure that the cited stability criteria are satisfied.

  9. 径向磁轴承的力学特性%Mechanical Characteristics of Radial Magnetic Bearing

    张钢; 虞烈; 谢友柏

    2001-01-01

    This paper is based on the example of a radial magnetic bearing possessed of eight-pole, and derives the calculation formulas of static and dynamic mechanical characteristics of the bearing, in which the shape and curvature of surface, eccentricity and tilt of the journal are taken into account. Variations of the static and dynamic characteristics of the radial magnetic bearing versus static tilt parameters of journal are discussed. The outcomes show that the static tilt of the journal has influence on the mechanical characteristics of radial magnetic bearing, and change the static load capacity between two radial magnetic bearings and exert coupling effect between them. To study the dynamics of a practical rotor-magnetic bearing system, at least six stiffness coefficients in each radial magnetic bearing must be considered in ideal case, and twelve stiffness coefficients must be considered in general case of tilting journal. Such a find can be used for the coupled electromechanical dynamics analysis of rotor system equipped with magnetic bearings.

  10. 径向磁轴承的力学特性%Mechanical Characteristics of Radial Magnetic Bearing

    张钢; 虞烈; 谢友柏

    2000-01-01

    This paper is based on the example of a radial magnetic bearing possessed of eight-pole, and derives the calculation formulas of static and dynamic mechanical characteristics of the bearing, in which the shape and curvature of surface, eccentricity and tilt of the journal are taken into account. Variations of the static and dynamic characteristics of the radial magnetic bearing versus static tilt parameters of journal are discussed. The outcomes show that the static tilt of the journal has influence on the mechanical characteristics of radial magnetic bearing, and change the static load capacity between two radial magnetic bearings and exert coupling effect between them. To study the dynamics of a practical rotor-magnetic bearing system, at least six stiffness coefficients in each radial magnetic bearing must be considered in ideal case, and twelve stiffness coefficients must be considered in general case of tilting journal. Such a find can be used for the coupled electromechanical dynamics analysis of rotor system equipped with magnetic bearings.

  11. Energy efficiency high speed drives with magnetic bearings; Energieeffizienz durch schnell drehende, magnetgelagerte Antriebe

    Kroll, Matthias [LEViTEC GmbH, Lahnau (Germany)

    2011-07-01

    In modern purification plans the contamination of the wastewater are biologically removed by supplying oxygen. The clarifier is ventilated by compressors around the clock and approximately 60% of the total energy consumption is used for that. It enables a great opportunity for saving energy. This contribution shows that the use of magnetic centrifugal compressors with high-speed drives leads to significant reduction of energy consumption. In addition, the drive is, due to contact free the magnetic bearings, practically wear- and maintenance-free. By the use of integrated sensors in the magnetic bearings a continuous monitoring of the compressor is implemented. Consequently this drive concept provides not only more efficiency and less energy consumption, but also leads to a higher plant availability. (orig.)

  12. A Method for stability analysis of magnetic bearings : Basic stability criteria

    Shayak, B

    2016-01-01

    In this work I outline a general procedure for dynamic modeling and stability analysis of a magnetic bearing, which is a rotating shaft confined inside a chamber through electromagnetic forces alone. I consider the simplest type of self-propelled bearing, namely a permanent magnet synchronous motor and an induction motor rotor freely suspended inside the corresponding stator, and having no eccentricity-fedback control algorithm. Writing Euler's equations for the rotor mechanics and Maxwell's equations for the electromagnetic field leads to a systematic technique for analysing the dynamics of the complete system. Physical arguments indicate that that two essential components for rotor confinement are a spatial gradient in the stator magnetic field and a torque angle lying in the second quadrant. These predictions are confirmed through the linear stability analysis. The direct practical utility of the results is mitigated by the presence of a repeated eigenvalue in the linearized equations. Despite this limitat...

  13. Development and characterization of magnetic HTS bearings for a 400 kW synchronous HTS motor

    Promising results of static and dynamic investigations on various journal type test bearings encouraged us to develop a scaled-up HTS bearing, able to carry the HTS rotor of a 400 kW superconducting motor. The stator, a YBCO hollow cylinder of 203 mm inner diameter and 250 mm length, is cooled by liquid nitrogen. Permanent magnet rings with a diameter of 200 mm were mounted on a shaft with alternating polarity. Characterization of the bearing capacity was performed with three different YBCO stators at temperatures between 66 and 86 K in a test set-up. A significant influence of the temperature was found. At a stator temperature of 72 K and a rotation frequency of 25 Hz (corresponding to nominal motor speed) a radial bearing force of 2700 N was measured for the shaft at centre position. Under rotation of the shaft the bearing capacity is reduced. At present our results range within the highest radial bearing capacities reported world-wide

  14. Radial Forces in a Centrifugal Compressor; Experimental Investigation by Using Magnetic Bearings and Static Pressure Distribution

    Arttu REUNANEN; Jaakko LARJOLA

    2005-01-01

    The volute of a centrifugal compressor causes a non-uniform pressure distribution which leads to a radial force on the impeller. This force was measured using magnetic bearings. In addition, the radial force was estimated using the static pressure distribution measured at the impeller outlet. The impeller force was found to be the highest at choke, the lowest at the design flow and moderate at stall. The radial force determined from the pressure measurements was only slightly different from the force obtained from the bearing measurements. The rotational speed was seen to affect the force to some extent.

  15. Experimental treatment of breast cancer-bearing BALB/c mice by artemisinin and transferrin-loaded magnetic nanoliposomes

    Amir Gharib

    2015-01-01

    Full Text Available Background: The combination of artemisinin and transferrin exhibits versatile anticancer activities. In previous, we successfully prepared artemisinin and transferrin-loaded magnetic nanoliposomes and evaluated their anti-proliferative activity against MCF-7 and MDA-MB-231 cell lines in vitro. In this study, we investigate the in vivo anti-breast cancer activity of artemisinin and transferrin-loaded magnetic nanoliposome against breast transplanted tumors in BALB/c mice model. Materials and Methods: Artemisinin and transferrin-loaded magnetic nanoliposomes were prepared and characterized for some physiochemical properties. Pieces of tumor tissue from the breast cancer-bearing BALB/c mice were transplanted subcutaneously to the syngeneic female BALB/c mice. In the presence of the external magnet that placed at the breast tumor site, the tissue distribution and tumor-suppressing effects of prepared nanoliposomes on tumor growth was evaluated. Results: The prepared nanoliposomes have fine spherical shape, rough surface, nano-sized diameter and magnetic properties. At 2 h after treatment, the intravenous administration of artemisinin and transferrin-loaded magnetic nanoliposomes followed using the magnetic field approximately produced 10- and 5.5-fold higher levels of artemisinin and transferrin in the tumors, respectively, compared with free artemisinin and transferrin. Moreover, in the presence of an external magnetic field, the prepared nanoliposomes could significantly induce apoptosis in the mice breast cancer cells as well as could reduce tumor volume in tumorized mice at 15 days after treatment. Conclusion: The data suggested that the artemisinin and transferrin-loaded magnetic nanoliposomes would be a good choice for the breast tumor-targeted therapy, due to its high targeting efficiency.

  16. Local Attitudes towards Bear Management after Illegal Feeding and Problem Bear Activity

    David Fraser; Sara Dubois

    2013-01-01

    Simple Summary The “pot bears” received international media attention in 2010 after police discovered the intentional feeding of black bears during the investigation of an alleged marijuana-growing operation in Christina Lake, British Columbia. Residents of this small community were surveyed by phone twice over the following year, before and after government actions. This study aimed to understand local attitudes on how these bears should be managed and whether they differed from existing bea...

  17. A contribution on the investigation of the dynamic behavior of rotating shafts with a Hybrid Magnetic Bearing Concept (HMBC) for blower application

    Within a subproject of the RAPHAEL-Program, which was part of the 6th EURATOM Framework Program supervised by the European Commission, it was investigated whether the use of a Hybrid Magnetic Bearing Concept (HMBC) will be beneficial for a blower application. Within the RAPHAEL program, the subproject 'Component Development' is dealing with R and D of components of High Temperature Reactor Technology (HTR), where a major focus is on safety- and reliability-related issues. That implies special requirements for the support of high speed rotating shafts in HTR-Applications that only can be satisfied by using Active Magnetic Bearings (AMB). Regarding safety and competitiveness, AMBs are considered to be key components for the support of rotating HTR-components due to their technical features. AMBs are characterized by an electromagnetic actuator that is generating the bearing force depending on the clearance between stator and rotor, in which the rotor is levitated. Therefore an active control of the coil current is necessary. Furthermore, Touch Down Bearings (TDB) are needed to avoid damages in case of an emergency shut down or in case of energy supply losses. This contribution provides an internal insight on the advantages of a Hybrid Magnetic Bearing Concept that is characterized by a completely Active Magnetic Bearing-supported vertical arranged rotor and an additional permanent magnetic radial orientated bearing. One benefit of the HMBC is an additional radial guidance of the shaft that may reduce the loads while dropping into the Touch Down Bearings e.g. in case of energy supply losses of the AMBs. Reduced loads on the TDBs will increase their life cycle and the availability of the AMB supported component. The scope of this R and D-Project, which will be described more detailed in this contribution, includes: the analytical modeling and simulation of the dynamic behavior of the Hybrid Magnetic Bearing System; the modification of the completely AMB-supported test

  18. A contribution on the investigation of the dynamic behaviour of rotating shafts with a hybrid magnetic bearing concept (HMBC) for blower application - HTR2008-58045

    Within a sub-project of the RAPHAEL-Program, which is part of the 6. EURATOM Framework Program supervised by the European Commission it was investigated whether the use of a Hybrid Magnetic Bearing Concept (HMBC) will be beneficial for a blower application. As in the RAPHAEL program the sub-project 'Component Development' deals with R and D on components of High Temperature Reactor Technology (HTR), a major focus is on safety- and reliability-related issues. That implies special requirements for the support of high speed rotating shafts in HTR-Applications that only can be satisfied by using Active Magnetic Bearings (AMB). Regarding safety and competitiveness, AMBs are considered key components for the support of rotating HTR-components due to their technical features. AMBs are characterized by an electromagnetic actuator that is generating the bearing force depending on the clearance between stator and rotor, in which the rotor is levitated. Therefore an active control of the coil current is necessary. Furthermore, Touch Down Bearings (TDB) are needed to avoid damages in case of an emergency shut down or in case of energy supply losses. This contribution provides an internal insight on the advantages of a Hybrid Magnetic Bearing Concept that is characterized by a completely Active Magnetic Bearing-supported vertical arranged rotor and an additional permanent magnetic Radial Bearing. One benefit of the HMBC is an additional radial guidance of the shaft that may reduce the loads while dropping into the Touch Down Bearings e.g. in case of energy supply losses of the AMBs. Reduced loads on the TDBs will increase their life cycle and the availability of the AMB supported component. The Scope of this R and D-Project, which will be described more detailed in this contribution, includes the analytical modeling and simulation of the dynamic behavior of the Hybrid Magnetic Bearing System, the modification of the completely AMB supported test facility FLP500 with a radial

  19. Influence of magnetic non-uniformity existing in a rigid rotor supported by a superconducting magnetic bearing on its whirling

    Superconducting magnetic bearings (SMBs) have a significant feature over conventional bearings in terms of supporting a shaft without physical contact while attaining its stability without control. In their large-scale rotary applications, magnetization distribution of a rotor in the circumferential direction can be non-uniform and it would be better to know influence of such circumferential magnetic non-uniformity existing in a rotor on its dynamics, especially on its behaviors in the vicinity of the critical speed. In this study, further developing our previous research, we improved our analytical model so that we can adjust several different degrees of magnetic non-uniformity by arranging multiple magnetization vectors and investigated its influence. First, we simulated dynamical behavior of the system by numerical calculations and their results show that, with increasing the degree of magnetic non-uniformity, the whirling amplitude of the system, together with the difference of the amplitudes in the orthogonal directions in the whirling plane, get larger. Further, the rotational frequency at which the whirling amplitude takes its peak gets lower, which is caused by nonlinearity of the electromagnetic force. We carried out experiments and verified our numerical predicions.

  20. MATLAB WEB SERVER AND ITS APPLICATION IN REMOTE COLLABORATIVE DESIGN OF MAGNETIC BEARING SYSTEMS

    2001-01-01

    Acclimatizing itself to the development of network,Math Works Inc constructed a MATLAB Web Server environment by dint of which one can browse the calculation and plots of MATLAB through Internet directly.The installation and use of the environment is introduced.A code established on the platform of MATLAB,which deals with the modal analysis of magnetic bearing system(MBS) supporting rotors of five degrees of freedom and considering the coupling of thrust bearing with radical bearings is modified to work in the environment.The purpose is to realize a remote call of the code by users through Internet for the performance analysis of the system.Such an application is very important to the concurrent design of MBS and for the utilization of distributive knowledge acquisition resources in collaborative design.The work on modification and realization is described and the results are discussed.

  1. Activity estimation in radioimmunotherapy using magnetic nanoparticles

    Rajabi, Hossein; Johari Daha, Fariba

    2015-01-01

    Objective Estimation of activity accumulated in tumor and organs is very important in predicting the response of radiopharmaceuticals treatment. In this study, we synthesized 177Lutetium (177Lu)-trastuzumab-iron oxide nanoparticles as a double radiopharmaceutical agent for treatment and better estimation of organ activity in a new way by magnetic resonance imaging (MRI). Methods 177Lu-trastuzumab-iron oxide nanoparticles were synthesized and all the quality control tests such as labeling yield, nanoparticle size determination, stability in buffer and blood serum up to 4 d, immunoreactivity and biodistribution in normal mice were determined. In mice bearing breast tumor, liver and tumor activities were calculated with three methods: single photon emission computed tomography (SPECT), MRI and organ extraction, which were compared with each other. Results The good results of quality control tests (labeling yield: 61%±2%, mean nanoparticle hydrodynamic size: 41±15 nm, stability in buffer: 86%±5%, stability in blood serum: 80%±3%, immunoreactivity: 80%±2%) indicated that 177Lu-trastuzumab-iron oxide nanoparticles could be used as a double radiopharmaceutical agent in mice bearing tumor. Results showed that 177Lu-trastuzumab-iron oxide nanoparticles with MRI had the ability to measure organ activities more accurate than SPECT. Conclusions Co-conjugating radiopharmaceutical to MRI contrast agents such as iron oxide nanoparticles may be a good way for better dosimetry in nuclear medicine treatment. PMID:25937783

  2. An active magnetic regenerator device

    2015-01-01

    A rotating active magnetic regenerator (AMR) device comprising two or more regenerator beds, a magnet arrangement and a valve arrangement. The valve arrangement comprises a plurality of valve elements arranged substantially immovably with respect to the regenerator beds along a rotational direction...

  3. Paleomagnetism and environmental magnetism of GLAD800 sediment cores from Bear Lake, Utah and Idaho

    Heil, C.W., Jr.; King, J.W.; Rosenbaum, J.G.; Reynolds, R.L.; Colman, Steven M.

    2009-01-01

    A ???220,000-year record recovered in a 120-m-long sediment core from Bear Lake, Utah and Idaho, provides an opportunity to reconstruct climate change in the Great Basin and compare it with global climate records. Paleomagnetic data exhibit a geomagnetic feature that possibly occurred during the Laschamp excursion (ca. 40 ka). Although the feature does not exhibit excursional behavior (???40?? departure from the expected value), it might provide an additional age constraint for the sequence. Temporal changes in salinity, which are likely related to changes in freshwater input (mainly through the Bear River) or evaporation, are indicated by variations in mineral magnetic properties. These changes are represented by intervals with preserved detrital Fe-oxide minerals and with varying degrees of diagenetic alteration, including sulfidization. On the basis of these changes, the Bear Lake sequence is divided into seven mineral magnetic zones. The differing magnetic mineralogies among these zones reflect changes in deposition, preservation, and formation of magnetic phases related to factors such as lake level, river input, and water chemistry. The occurrence of greigite and pyrite in the lake sediments corresponds to periods of higher salinity. Pyrite is most abundant in intervals of highest salinity, suggesting that the extent of sulfidization is limited by the availability of SO42-. During MIS 2 (zone II), Bear Lake transgressed to capture the Bear River, resulting in deposition of glacially derived hematite-rich detritus from the Uinta Mountains. Millennial-scale variations in the hematite content of Bear Lake sediments during the last glacial maximum (zone II) resemble Dansgaard-Oeschger (D-O) oscillations and Heinrich events (within dating uncertainties), suggesting that the influence of millennial-scale climate oscillations can extend beyond the North Atlantic and influence climate of the Great Basin. The magnetic mineralogy of zones IV-VII (MIS 5, 6, and 7

  4. Preliminary study on rotor dynamics of magnetic bearing for 10MW high temperature gas-cooled reactor

    The finite element method and MSC. Marc software are applied to analyze the rotor modal of magnetic bearings for power conversion unit (PCU) of 10 MW high temperature gas-cooled reactor (HTR-10). The effects of the magnetic bearings sustaining stiffness on the rotor natural frequencies were studied. Results show that the natural frequencies may be adjusted by changing the sustaining stiffness and rotor material. It is very important for the magnetic bearing to pass two order bending natural frequencies and design control system

  5. Nonlinear dynamic behaviour of a rotor-foundation system coupled through passive magnetic bearings with magnetic anisotropy - Theory and experiment

    Enemark, Søren; Santos, Ilmar F.

    2016-01-01

    the frequency domain by the methods of Finite Difference and pseudo-arclength continuation. The theoretical findings are validated against experiments carried out using a dedicated test-rig and a special device for characterisation of the magnetic anisotropy.The characterisation of the magnetic...... and nonlinear cross-coupling between the two orthogonal directions, especially during counter-phase motion between shaft and bearings. The clear nonlinear behaviour is facilitated by the lack of damping resulting in relatively large vibrations. The overall nonlinear dynamic behaviour is well captured...

  6. DESIGN AND APPLICATION OF MAGNETIC BEARING SUSPENSION SYSTEM IN A THREE PHASE INDUCTION MOTOR

    Osman GÜRDAL; Yusuf ÖNER

    1998-01-01

    The current popularity of suspension and levitation stems no doubt the possibilities in high-speed ground transportation schemes. Although these are both challenging and exciting, there is considerable scope for application of suspension techniques to achieving frictionless bearing. The requirement in this case is often for close tolerances, low power consumption, small airgaps and ingeneral, compactness. Thus, magnetic suspension using DC electromagnets schemes have received more attention t...

  7. Multiple stabilities analysis in a magnetic bearing system with time delays

    A kind of magnetic bearing system with time delay is considered. Firstly, multiple stabilities of the model is investigated. According to the analysis results, the bifurcation diagram is drawn in the appropriate parameter plane. Then the center manifold reduction and normal form computation for simple zero singularity are performed and detailed bifurcation analysis are carried out. Finally, some numerical simulations are presented to illustrate the results found

  8. Study on alkali leaching of a complicated uranium-bearing magnetic concentrate

    Alkali leaching of a complicated uranium-bearing magnetic concentrate was studied. The research results showed that the uranium recovery from the concentrate leaching increased with destruction and dissolution of organic matters. It is suitable and feasible to treat the magnetic concentrate by a two-stage alkali leaching process including pre-leaching, and it is beneficial to treat the obtained product solution in the subsequent operations. It is extremely possible that the residual uranium in the leached residue is closely associated with hard-to-open davidite. So it is not reasonable economically to continue intensifying the conditions to treat the concentrate

  9. Sliding Mode Output Feedback Control of a Flexible Rotor Supported by Magnetic Bearings

    A. S. Lewis

    2001-01-01

    Full Text Available A new sliding mode feedback algorithm is applied to control the vibration of a flexible rotor supported by magnetic bearings. It is assumed that the number of states is greater than the number of sensors. A mathematical model of the rotor]magnetic bearing system is presented in terms of partial differential equations. These equations are then discretized into a finite number of ordinary differential equations through Galerkin’s method. The sliding mode control law is designed to be robust to rotor unbalance and transient disturbances. A boundary layer is introduced around each sliding hyperplane to eliminate the chattering phenomenon. The results from numerical simulations are presented that not only corroborate the validity of the proposed controller, but also show the effects of various control parameters as a function of the angular speed of the rotor. In addition, results are presented that indicate how the current required by the magnetic bearings is affected by control parameters and the angular speed of the rotor.

  10. Performance of an active electric bearing for rotary micromotors

    An electric bearing used to support a micromachined rotor of variable-capacitance motors was designed and tested in order to study the characteristics of this frictionless bearing. Electrostatic suspension of a ring-shaped rotor in five degrees of freedom is required to eliminate the mechanical bearing and thus the friction and wear between the rotor and the substrate. Bulk microfabrication-based glass/silicon/glass bonding is chosen for this device, allowing the fabrication of large area sense capacitors and rotor, which make the device potentially suitable for the development of an electrostatically suspended micromachined gyroscope. The device and its basic operating principle are described, as well as the dynamics of the rotor and basic design considerations of the electric bearing system. A theoretical relationship to relate the characteristics of a classical lag–lead compensator to the stiffness properties of the electric bearing is developed to explain the experimental bearing measurements. The experimental results of closed-loop frequency response, suspension stiffness and drive voltage effects are presented and discussed for the bearing operated initially in the atmospheric environment. The performance of a tri-axial electrostatic accelerometer has also been experimentally investigated on the prototype of the electric bearing system

  11. Performance Testing of a Magnetically Suspended Double Gimbal Control Moment Gyro Based on the Single Axis Air Bearing Table

    2012-01-01

    Integrating the advantage of magnetic bearings with a double gimble control moment gyroscope (DGCMG), a magnetically suspended DGCMG (MSDGCMG) is an ideal actuator in high-precision, long life, and rapid maneuver attitude control systems. The work presented here mainly focuses on performance testing of a MSDGCMG independently developed by Beihang University, based on the single axis air bearing table. In this paper, taking into sufficient consideration to the moving-gimbal effects and the res...

  12. Feasibility of Applying Active Lubrication to Dynamically Loaded Fluid Film Bearings

    Estupinan, Edgar Alberto; Santos, Ilmar

    2009-01-01

    The feasibility of modifying the dynamics of the thin fluid films of dynamically loaded journal bearings, using different strategies of active lubrication is studied in this work. A significant reduction in the vibration levels, wear and power friction losses, is expected. Particularly, the focus...... of this study is on the analysis of main crankshaft bearings, where the conventional hydrodynamic lubrication is modified by injecting oil at actively controllable pressures, through orifices circumferentially located along the bearing surface....

  13. 磁悬浮轴承-转子系统非线性行为的控制%Control of Nonlinear Behaviors of an Active Magnetic Bearing - Rotor System

    孙保苍; 梁荣生; 陈威

    2011-01-01

    利用状态反馈法,对磁悬浮轴承-转子系统的振动进行控制.通过理论推导,证明在原点附近,可近似地将受控系统分解为两个渐近稳定的子系统之和.借助数值仿真对转子受控前后的运动响应进行分析,以验证该控制方案的有效性.通过比较发现,提出的状态反馈控制方案不但能控制转子的周期运动,而且对该系统的概周期运动和混沌运动也能进行有效控制.%In this paper, the nonlinear dynamical behaviors of an active magnetic beating-rotor system are investigated.In order to control the vibration of the system, a state feedback method is adopted.It is theoretically proved that the controlled system can be approximately divided into two asymptotically stable subsystems near the origin.Based on this conclusion, kinematic responses to both controlled and uncontrolled systems are analyzed by numerical simulations to verify the validity of the control scheme.Mutual comparison of the results of both systems reveals that the state feedback control scheme presented here can effectively control not only periodic vibrations, but also quasi-periodic and chaotic vibrations.

  14. From Hybrid to Actively-Controlled Gas Lubricated Bearings – Theory and Experiment

    Morosi, Stefano

    bearings, tilting pad and flexure pivot gas bearings. These solutions proved to be effective in improving static and dynamic properties of the bearings, however issues related to the manufacturing and accuracy of predictions has so far limited their applications. Another drawback is that passive bearings...... determined by the appearance of subsynchronous whirl instability. In fact, postponing the onset speed of instability poses one of the greatest challenges in high-speed gas bearing design. A great deal of research is devoted to attack such issues, where most propose passive designs such as compliant foil...... offer a low degree of robustness, meaning that an accurate optimization is necessary for each application. Another way of improving gas bearings operation performance is by using active control systems, transforming conventional gas bearings in an electro-mechanical machine component. In this framework...

  15. Linear and Nonlinear Analysis of Magnetic Bearing Bandwidth Due to Eddy Current Limitations

    Kenny, Andrew; Palazzolo, Alan

    2000-01-01

    Finite element analysis was used to study the bandwidth of alloy hyperco50a and silicon iron laminated rotors and stators in magnetic bearings. A three dimensional model was made of a heteropolar bearing in which all the flux circulated in the plane of the rotor and stator laminate. A three dimensional model of a plate similar to the region of a pole near the gap was also studied with a very fine mesh. Nonlinear time transient solutions for the net flux carried by the plate were compared to steady state time harmonic solutions. Both linear and quasi-nonlinear steady state time harmonic solutions were calculated and compared. The finite element solutions for power loss and flux bandwidth were compared to those determined from classical analytical solutions to Maxwell's equations.

  16. Control system design for flexible rotors supported by actively lubricated bearings

    Nicoletti, Rodrigo; Santos, Ilmar

    2008-01-01

    and keeping the lengths of the two eigenvalues constant in the real-imaginary plane. The methodology is applied to an industrial gas compressor supported by active tilting-pad journal bearings. The unbalance response functions and mode shapes of the flexible rotor with and without active control are...... displacement and velocity of the shaft at the bearing positions....

  17. Magnetic mineralogy analyses on greigite-bearing sediments with inconsistent magnetic polarity (Adana Basin, Southern Turkey)

    Lucifora, S.; Cifelli, F.; Mattei, M.; Cosentino, D.; Sagnotti, L.; Roberts, A.

    2012-04-01

    A paleomagnetic study has been carried out, in the framework of the VAMP (Vertical Anatolian Movement Project) project, on 4 stratigraphic sections and 1 site from the Adana basin in the southern margin of the Anatolian Plateau. About 300 standard cylindrical samples have been analysed for paleomagnetism and rock magnetism. All the sections have been deposited in the upper Messinian"lago-mare" post-evaporitic event, which occurred in the Mediterranean basin, during the reverse polarity Chron C3r. Paleomagnetic results, presented in this work, are in contrast with these data, showing both normal and reverse polarities along the sections. Standard magnetic mineralogy investigations, integrated with SEM analyses and FORC diagrams, show that magnetite and ferrimagnetic iron sulphides (greigite) are the main magnetic carriers. Moreover, we find an interesting correlation between the magnetic mineralogy of the sediments and the magnetic polarities, being magnetite the magnetic carrier in the normal polarity samples and greigite in the reverse ones. Reversal and fold tests demonstrate that normal polarity samples have been subjected to a pervasive magnetic overprint and acquired their remanent magnetization after bedding tilt. Whereas samples with a reverse polarity acquired their remanent magnetization before bedding tilt, but after syn-sedimentary soft deformation. This work is proposed as a contribution aimed to improve the understanding of the relationship between the magnetic mineralogy and the remagnetization phenomena in order to avoid misinterpretation of magnetostratigraphic and paleomagnetic data.

  18. Elastohydrodynamics Applied to Active Tilting-Pad Journal Bearings

    Haugaard, Martin Asger; Santos, Ilmar

    2010-01-01

    The static and dynamic properties of tilting-pad journal bearings with controllable radial oil injection are investigated theoretically. The tilting pads are modeled as flexible structures and their behavior is described using a three-dimensional finite element framework and linear elasticity. The...... dynamically perturbed and subsequently condensed to a 2 X 2 system, keeping only the lateral motion of the rotor. As expected, bearing dynamic coefficients are heavily influenced by the control parameters and pad compliance....

  19. Cryogenic magnetic bearing scanning mechanism design for the SPICA/SAFARI Fourier transform spectrometer

    van den Dool, Teun C.; Hamelinck, Roger F. M. M.; Kruizinga, Bob; Gielesen, Wim L. M.; Braam, Ben C.; Nijenhuis, Jan R.; Loix, Nicolas; Luyckx, Stanislas; van Loon, Dennis; Kooijman, Peter Paul; Swinyard, Bruce M.

    2010-07-01

    TNO, together with its partners Micromega and SRON, have designed a cryogenic scanning mechanism for use in the SAFARI Fourier Transform Spectrometer (FTS) on board of the SPICA mission. The optics of the FTS scanning mechanism (FTSM) consists of two back-to-back cat's-eyes. The optics are mounted on a central "back-bone" tube which houses all the important mechatronic parts: the magnetic bearing linear guiding system, a magnetic linear motor serving as the OPD actuator, internal metrology with nanometer resolution, and a launch lock. A magnetic bearing is employed to enable a large scanning stroke in a small volume. It supports the optics in a free-floating way with no friction, or other non-linearities, enabling sub-nanometer accuracy within a single stage with a stroke of -4 mm to +31.5 mm. Because the FTSM will be used at cryogenic temperatures of 4 Kelvin, the main structure and optics are all constructed from 6061 Aluminum. The overall outside dimensions of the FTSM are: 393 x 130 x 125 mm, and the mass is 2.2 kg.

  20. Stability and bifurcation analysis in a magnetic bearing system with time delays

    A kind of magnetic bearing system with time delay is considered. Firstly, linear stability of the model is investigated by analyzing the distribution of the roots of the associated characteristic equation. According to the analysis results, the bifurcation diagram is drawn in the appropriate parameter plane. It is found that the Ho pf bifurcation occurs when the delay passes through a sequence of critical values. Then the explicit algorithm for determining the direction of the Ho pf bifurcations and the stability of the bifurcating periodic solutions are derived, using the theory of normal form and center manifold. Finally, some numerical simulations are carried out to illustrate the results found

  1. Effect of unbalanced magnetic pull and hydraulic seal force on the vibration of large rotor-bearing systems

    The influence of unbalanced magnetic pull (UMP) and hydraulic seal force on the vibration of large rotor-bearing systems is studied. The UMP caused by rotor eccentricity imposes important effects on rotating machinery, especially for large generators such as water turbine generator sets, because these machines operate above their first critical speed in some instances and are supported by oil film bearings. A magnetic stiffness matrix for studying the effects of the UMP is proposed. The magnetic stiffness matrix can be generated by decomposing the expression of air gap magnetic field energy. Two vibration models are constructed using the Lagrange equation. The difference between the two models lies in the boundary support condition: one has rigid support and the other has elastic bearing support. The influence of the magnetic stiffness and elastic support on the critical speed of the rotor is studied using Lyapunov nonlinear vibration stability theory. The vibration amplitude of the rotor is calculated, taking the magnetic stiffness and horizontal centrifugal force into account. The unbalanced hydraulic seal force is produced because of the asymmetry of seal clearance. This imbalance is one of the factors that causes self-excited vibration in rotating machinery, and is as important as the UMP for large water turbine generator sets. The rotor-bearing system is supported by an oil film journal bearing, whose characteristic also impose considerable influence on vibration. On the basis of the above-mentioned conditions, a three-dimensional finite element model of the rotating system that includes the oil film journal bearing is constructed. The effect of the UMP and unbalanced hydraulic seal force is considered in the construction, and studied in relation to the magnetic parameters, seal parameters, journal bearing stiffness, and outer diameter of the rotating machine critical speed. Conclusions may benefit the dynamic design and optimized operation of large rotating

  2. Effect of unbalanced magnetic pull and hydraulic seal force on the vibration of large rotor-bearing systems

    Song, Z.; Guo, P.; Liu, Y.

    2014-03-01

    The influence of unbalanced magnetic pull (UMP) and hydraulic seal force on the vibration of large rotor-bearing systems is studied. The UMP caused by rotor eccentricity imposes important effects on rotating machinery, especially for large generators such as water turbine generator sets, because these machines operate above their first critical speed in some instances and are supported by oil film bearings. A magnetic stiffness matrix for studying the effects of the UMP is proposed. The magnetic stiffness matrix can be generated by decomposing the expression of air gap magnetic field energy. Two vibration models are constructed using the Lagrange equation. The difference between the two models lies in the boundary support condition: one has rigid support and the other has elastic bearing support. The influence of the magnetic stiffness and elastic support on the critical speed of the rotor is studied using Lyapunov nonlinear vibration stability theory. The vibration amplitude of the rotor is calculated, taking the magnetic stiffness and horizontal centrifugal force into account. The unbalanced hydraulic seal force is produced because of the asymmetry of seal clearance. This imbalance is one of the factors that causes self-excited vibration in rotating machinery, and is as important as the UMP for large water turbine generator sets. The rotor-bearing system is supported by an oil film journal bearing, whose characteristic also impose considerable influence on vibration. On the basis of the above-mentioned conditions, a three-dimensional finite element model of the rotating system that includes the oil film journal bearing is constructed. The effect of the UMP and unbalanced hydraulic seal force is considered in the construction, and studied in relation to the magnetic parameters, seal parameters, journal bearing stiffness, and outer diameter of the rotating machine critical speed. Conclusions may benefit the dynamic design and optimized operation of large rotating

  3. Radial forces analysis and rotational speed test of radial permanent magnetic bearing for horizontal axis wind turbine applications

    Kriswanto, Jamari

    2016-04-01

    Permanent magnet bearings (PMB) are contact free bearings which utilize the forces generated by the magnets. PMB in this work is a type of radial PMB, which functions as the radial bearings of the Horizontal Axis Wind Turbine (HAWT) rotor shaft. Radial PMB should have a greater radial force than the radial force HAWT rotor shaft (bearing load). This paper presents a modeling and experiments to calculate the radial force of the radial PMB. This paper also presents rotational speed test of the radial PMB compared to conventional bearings for HAWT applications. Modeling using COMSOL Multiphysics 4.3b with the magnetic fields physics models. Experiments were conducted by measuring the displacement of the rotor to the stator for a given load variation. Results of the two methods showed that the large displacement then the radial force would be greater. Radial forces of radial PMB is greater than radial forces of HAWT rotor shaft. The rotational speed test results of HAWT that used radial PMB produced higher rotary than conventional bearings with an average increase of 87.4%. Increasing rotational speed occured because radial PMB had no friction. HAWT that used radial PMB rotated at very low wind speeds are 1.4 m/s with a torque of 0.043 Nm, while the HAWT which uses conventional bearing started rotating at a wind speed of 4.4 m/s and required higher torque of 0.104 N.

  4. Influence of Back-Up Bearings and Support Structure Dynamics on the Behavior of Rotors With Active Supports

    Flowers, George T.

    1996-01-01

    This report presents a synopsis of the research work. Specific accomplishments are itemized below: (1) Experimental facilities have been developed. This includes a magnetic bearing test rig and an auxiliary bearing test rig. In addition, components have been designed, constructed, and tested for use with a rotordynamics test rig located at NASA Lewis Research Center. (2) A study of the rotordynamics of an auxiliary bearing supported T-501 engine model was performed. (3) An experimental/simulation study of auxiliary bearing rotordynamics has been performed. (4) A rotordynamical model for a magnetic bearing supported rotor system, including auxiliary bearing effects has been developed and simulation studies performed.(5) A finite element model for a foil bearing has been developed and studies of a rotor supported by foil bearings have been performed. (6) Two students affiliated with this project have graduated with M.S. degrees.

  5. Collection of Ni-bearing material from electroless plating waste by magnetic separation with HTS bulk magnet

    Oka, T., E-mail: okat@eng.niigata-u.ac.jp [Niigata University, 8050 Ikarashi-Ninocho, Nishi-ku, Niigata 950-2181 (Japan); Fukazawa, H.; Fukui, S.; Ogawa, J.; Sato, T.; Ooizumi, M. [Niigata University, 8050 Ikarashi-Ninocho, Nishi-ku, Niigata 950-2181 (Japan); Tsujimura, M. [Aichi Giken Co., 50-1 Takeshita, Hitotugi-cho, Kariya, Aichi 448-0003 (Japan); Yokoyama, K. [Ashikaga Institute of Technology, 268-1 Ohmae-cho, Ashikaga, Tochigi 326-8558 (Japan)

    2014-01-15

    Highlights: ► The magnetic separation for Ni compounds was conducted by HTS bulk magnet. ► The coarse Ni-sulfate crystals were formed from the Ni-phosphite precipitates. ► Ni-sulfate crystals was separated from the mixture of Ni-sulfate and Ni-phosphite compounds. -- Abstract: The magnetic separation experiment to collect the Ni compounds from the waste liquid of electroless plating processes was conducted in the open-gradient magnetic separation process with the high temperature superconducting bulk magnet system. The magnetic pole containing Gd-based bulk superconductors was activated to 3.45 T at 35 K in the static magnetic field of 5 T with use of a superconducting solenoid magnet. The coarse Ni-sulfate crystals were formed by adding the concentrated sulfuric acid to the Ni-phosphite precipitates which yielded from the plating waste liquid by controlling the temperature and the pH value. The open-gradient magnetic separation technique was employed to separate the Ni-sulfate crystals from the mixture of the Ni-sulfate and Ni-phosphite compounds by the difference between their magnetic properties. And we succeeded in collecting Ni-sulfate crystals preferentially to the Ni-phosphite by attracting them to the magnetic pole soon after the Ni-sulfate crystals began to grow.

  6. Summer declines in activity and body temperature offer polar bears limited energy savings

    Whiteman, J.P.; Harlow, H.J.; Durner, George M.; Anderson-Sprecher, R.; Albeke, Shannon E.; Regehr, Eric V.; Amstrup, Steven C.; Ben-David, M.

    2015-01-01

    Polar bears (Ursus maritimus) summer on the sea ice or, where it melts, on shore. Although the physiology of “ice” bears in summer is unknown, “shore” bears purportedly minimize energy losses by entering a hibernation-like state when deprived of food. Such a strategy could partially compensate for the loss of on-ice foraging opportunities caused by climate change. However, here we report gradual, moderate declines in activity and body temperature of both shore and ice bears in summer, resembling energy expenditures typical of fasting, nonhibernating mammals. Also, we found that to avoid unsustainable heat loss while swimming, bears employed unusual heterothermy of the body core. Thus, although well adapted to seasonal ice melt, polar bears appear susceptible to deleterious declines in body condition during the lengthening period of summer food deprivation.

  7. Animal physiology. Summer declines in activity and body temperature offer polar bears limited energy savings.

    Whiteman, J P; Harlow, H J; Durner, G M; Anderson-Sprecher, R; Albeke, S E; Regehr, E V; Amstrup, S C; Ben-David, M

    2015-07-17

    Polar bears (Ursus maritimus) summer on the sea ice or, where it melts, on shore. Although the physiology of "ice" bears in summer is unknown, "shore" bears purportedly minimize energy losses by entering a hibernation-like state when deprived of food. Such a strategy could partially compensate for the loss of on-ice foraging opportunities caused by climate change. However, here we report gradual, moderate declines in activity and body temperature of both shore and ice bears in summer, resembling energy expenditures typical of fasting, nonhibernating mammals. Also, we found that to avoid unsustainable heat loss while swimming, bears employed unusual heterothermy of the body core. Thus, although well adapted to seasonal ice melt, polar bears appear susceptible to deleterious declines in body condition during the lengthening period of summer food deprivation. PMID:26185248

  8. Solar activity monitoring and forecasting capabilities at Big Bear Solar Observatory

    P. T. Gallagher

    Full Text Available The availability of full-disk, high-resolution Ha images from Big Bear Solar Observatory (USA, Kanzelhöhe Solar Observatory (Austria, and Yunnan Astronomical Observatory (China allows for the continual monitoring of solar activity with unprecedented spatial and temporal resolution. Typically, this Global Ha Network (GHN provides almost uninterrupted Ha images with a cadence of 1 min and an image scale of 1'' per pixel. 

    Every hour, GHN images are transferred to the web-based BBSO Active Region Monitor (ARM; www.bbso.njit.edu/arm, which includes the most recent EUV, continuum, and magnetogram data from the Solar and Heliospheric Observatory, together with magnetograms from the Global Oscillation Network Group. ARM also includes a variety of active region properties from the National Oceanic and Atmospheric Administration’s Space Environment Center, such as up-to-date active region positions, GOES 5-min X-ray data, and flare identification. Stokes I, V, Q, and U images are available from the recently operational BBSO Digital Vector Magnetograph and the Vector Magnetograph at the Huairou Solar Observing Station of Beijing Observatory. Vector magnetograms provide complete information on the photospheric magnetic field, and allow for magnetic flux gradients, electric currents, and shear forces to be calculated: these measurements are extremely sensitive to conditions resulting in flaring activity. Furthermore, we have developed a Flare Prediction System which estimates the probability for each region to produce C-, M-, or X-class flares based on nearly eight years of NOAA data from cycle 22. This, in addition to BBSO’s daily solar activity reports, has proven a useful resource for activity forecasting.

    Key words. Solar physics, astronomy and astrophysics (flares and mass ejections; instruments and techniques

  9. Modeling and Analysis of Coupling Performance of Dynamic Stiffness Models for a Novel Combined Radial-Axial Hybrid Magnetic Bearing

    Bangcheng Han

    2014-01-01

    Full Text Available The combined radial-axial magnetic bearing (CRAMB with permanent magnet creating bias flux can reduce the size, cost, and mass and save energy of the magnetic bearing. The CRAMB have three-degree-of-freedom control ability, so its structure and magnetic circuits are more complicated compared to those of the axial magnetic bearing (AMB or radial magnetic bearing (RMB. And the eddy currents have a fundamental impact on the dynamic performance of the CRAMB. The dynamic stiffness model and its cross coupling problems between different degrees of freedom affected for the CRAMB are proposed in this paper. The dynamic current stiffness and the dynamic displacement stiffness models of the CRAMB are deduced by using the method of equivalent magnetic circuit including eddy current effect, but the dynamic current stiffness of the RMB unit is approximately equal to its static current stiffness. The analytical results of an example show that the bandwidth of the dynamic current stiffness of the AMB unit and the dynamic displacement stiffness of the CRAMB is affected by the time-varying control currents or air gap, respectively. And the dynamic current stiffness and the dynamic displacement stiffness between the AMB unit and the RMB unit are decoupled due to few coupling coefficients.

  10. Authigenesis of magnetic minerals in gas hydrate-bearing sediments in the Nankai Trough, offshore Japan

    Kars, Myriam; Kodama, Kazuto

    2015-03-01

    Gas hydrate occurrence is one of the possible mechanisms invoked for iron sulfide formation. A high-resolution rock magnetic study was conducted in IODP Expedition 316 Hole C0008C located in the Megasplay Fault Zone of the Nankai Trough, offshore Japan. In this particular zone, no bottom simulating reflectors (BSR), indicating the base of the gas hydrate stability field, have been identified. Two hundred and eighteen Pleistocene samples were collected from 70 to 110 m CSF in order to document the changes in the concentration, grain size, and rock magnetic parameters of magnetic minerals, through the gas hydrate-bearing horizons. Two different populations of magnetic grains are recognized in the pseudosingle domain range. Three types of magnetic mineral assemblages are identified: iron oxides (magnetite), ferrimagnetic iron sulfides (greigite and pyrrhotite), and their mixture. Greigite and pyrrhotite are authigenic and constitute six layers, called IS1-IS6. IS1, IS3, IS4, and IS6 are associated with pore water anomalies, suggesting the occurrence of gas hydrates and anoxic conditions. IS2 and IS5 are probable gas hydrates horizons, although there is no independent data to confirm it. The remaining intervals are mainly composed of detrital iron oxides and paramagnetic iron sulfides. Two scenarios based on different diagenetic stages are proposed to explain the variations in the magnetic properties and mineralogy over the studied interval. The results suggest that rock magnetism appears useful to better constrain the gas hydrate distribution in Hole C0008C, and counterbalances the low resolution of pore water analyses and the absence of a BSR.

  11. Linear and Non-Linear Control Techniques Applied to Actively Lubricated Journal Bearings

    Nicoletti, Rodrigo; Santos, Ilmar

    2003-01-01

    The main objectives of actively lubricated bearings are the simultaneous reduction of wear and vibration between rotating and stationary machinery parts. For reducing wear and dissipating vibration energy until certain limits, one can count with the conventional hydrodynamic lubrication. For...... further reduction of shaft vibrations one can count with the active lubrication action, which is based on injecting pressurised oil into the bearing gap through orifices machined in the bearing sliding surface. The design and efficiency of some linear (PD, PI and PID) and non-linear controllers, applied...... to a tilting-pad journal bearing, are analysed and discussed. Important conclusions about the application of integral controllers, responsible for changing the rotor-bearing equilibrium position and consequently the "passive" oil film damping coefficients, are achieved. Numerical results show an...

  12. Three Types of Active Lubrication Systems for the Main Bearings of Reciprocating Machines

    Santos, Ilmar; Pulido, E. E.

    2010-01-01

    In the paper the authors investigate three different schemes for the realization of the controllable oil injection system to be couple to the main engine bearings. The use of active lubrication in fluid film bearings helps to enhance the hydrodynamic fluid film by increasing the fluid film...... engine, where the conventional lubrication of the main bearing is modified by applying radial oil injection. The performance of such a hybrid bearing is compared to an equivalent conventional lubricated bearing in terms of the maximum fluid film pressures, minimum fluid film thicknesses and reduction of...... thickness and consequently reducing viscous friction losses and vibrations. One refers to active lubrication when conventional hydrodynamic lubrication is combined with dynamically modified hydrostatic lubrication. In this case, the hydrostatic lubrication is modified by injecting oil at controllable...

  13. Program for tests on magnetic bearing suspended rotor dynamics for gas turbine high temperature reactor (GTHTR300)

    A program for test on rotor dynamics was planned for the turbo-machine of the Gas Turbine High Temperature Reactor (GTHTR300). The rotor system of the turbo-machine consists of a turbo-compressor rotor and a generator rotor connected with a flexible coupling, each suspended with two radial magnetic bearings. The rotors, which are flexible rotors, pass over the critical speeds of bending mode. The magnetic bearing is required to have a high load capacity, about 10 times larger than any built thus far to support a flexible rotor. In the rotor design, the standard limit of the vibration amplitude of 75 μm at the rated rotational speed of 3,600 rpm was fulfilled by optimizing the stiffness of the magnetic bearings. A test apparatus was designed to verify the design of the magnetic bearing suspended turbo-machine rotor of the GTHTR300. The test apparatus is composed of 1/3-scale test rotors, which are connected with a flexible coupling and driven by a variable speed motor. The test magnetic bearing was designed within the state-of-the-art technology to have a load capacity about 1/10 of that of the actual one. The test rotors were designed to closely simulate the critical speeds and vibration modes of the actual ones. This paper shows the test apparatus and the test plan for the magnetic bearing suspended rotor system. The present study is entrusted from the Ministry of Education, Culture, Sports, Science and Technology of Japan. (author)

  14. Analysis on Dynamic Performance for Active Magnetic Bearing—Rotor System

    YANHui-yan; WANGXi-ping; 等

    2001-01-01

    In the application of active magnetic bearings(AMB),one of the key problems to be solved is the safety and stabiltiy in the sense of rotor dynamics,The project related to the present paper deals with the method for analyzing bearing rotor systems with high rotation speed and specially supported by active magnetic bearings,and studies its rotor dynamics performance,including calculation of the natural frequencies with their distribution characteristics,and the critical speeds of the system.one of the targets of this project is to formulate a theory and method valid for the analysis of the dynamic performance of the active magntic bearing-rotor systemby combining the traditional theory and method of rotor dynamics with the analytical theory and design method based on modern control theory of the AMB system.

  15. Low- and high-temperature magnetic properties of iron-bearing particles of combustion origin

    Kim, W.; Doh, S. J.; Yu, Y.; Moon, J. W.

    2012-04-01

    Magnetic particulates in the urban atmosphere are often observed in the forms of spherules and aggregates derived from iron impurities in fossil fuels upon combustion. Recently, magnetic properties of various atmospheric samples gather a scientific interest as economic and rapid proxies in the pollution studies based on their strong linkage to heavy metals and/or volatile organic carbons. Here we present low- and high-temperature magnetic properties of iron-bearing spherules and aggregates separated from the dry-deposit of aerosols and vehicle exhaust emission, respectively. Spherical particles behave like magnetite with the domain state of pseudo-single-domain even for larger than 10 μm in diameter. This probably involves the growth of magnetite branching small particles with a dendritic texture. For the aggregates containing abundant sulfur, only a magnetite signal can be found in low-temperature but both pyrrhotite and magnetite signals occur in high-temperature. Such discrepancy indicates that aggregates of magnetite-like particles with non-monoclinic pyrrhotite due to the absence of low-temperature transition in remanence at around 30 - 35 K.

  16. Tilting-Pad Journal Bearings with Active Lubrication Applied as Calibrated Shakers: Theory and Experiment

    Cerda Varela, Alejandro Javier; Santos, Ilmar

    2014-01-01

    In recent years, a continuous research effort has transformed the conventional tilting-pad journal bearing into a mechatronic machine element. The addition of electromechanical elements provides the possibility of generating controllable forces over the rotor as a function of a suitable control...... dependent calibration function, i.e. the transfer function between control signal and force over the rotor. This work presents a theoretical model of the calibration function for a tilting-pad journal bearing with active lubrication. The bearing generates controllable forces by injecting pressurized oil...... signal. Such forces can be applied in order to perform parameter identification procedures in-situ, which enables evaluation of the mechanical condition of the machine in a non-invasive way. The usage of a controllable bearing as a calibrated shaker requires obtaining the bearing specific frequency...

  17. Sensorless Speed Control of a Permanent Magnet Type Axial Gap Self Bearing Motor

    Nguyen, Dich Quang; Ueno, Satoshi

    The goal of this paper is use the Luenberger observer to research a new capability of controlling the axial gap self bearing motor, in which an analytical and experimental evaluation of a sensorless speed vector control of a permanent magnet type axial gap self bearing motor is presented. Rotor speed and position are estimated by using a state observer, not by using any shaft mounted position sensor as encoder or resolver etc. The approach is based on the estimation of the motor back-EMF (or induced voltage) through a Luenberger observer with help of measured stator currents and reference voltages. In order to achieve an accurate estimation of the rotor speed and position in all operating range, adaptive gain of observer controller is proposed. Furthermore, due to the change of air gap at the practical experiment, a compensation procedure also assures the system working stably at any axial position of rotor. The experiment is implemented based on dSpace1104 with two three-phase inverters. Results confirm that axial force and rotating torque can be controlled independently and motor can get the good performance in steady state at the average and high speed range.

  18. 5th workshop 'Magnetic bearings'. Proceedings; 5. Workshop Magnetlagertechnik. Tagungsband

    Gaertner, S.; Rottenbach, T. (comps.)

    2001-07-01

    The workshop investigated the state of the art of magnetic bearings and their applications. It was attended by experts from industry, research institutions and universities who took the chance to exchange their experience and keep abreast of new developments. The proceedings volume contains all papers presented at the meeting, in chronological order. [German] Der Workshop stellt sich zur Aufgabe, sowohl die Fortschritte in Forschung und Entwicklung in der Magnetlagertechnik aufzuzeigen als auch den Stand der Technik an speziellen Anwendungen darzustellen. Die Veranstaltung versteht sich als Forum fuer Forscher und Anwender aus der Industrie, industriellen Forschungseinrichtungen sowie Universitaeten und Hochschulen. Daher steht der Erfahrungsaustausch zwischen Entwicklern, Herstellern und Betreibern im Mittelpunkt. Interessierte Fachleute aus Wissenschaft und Industrie haben hier die Moeglichkeit, sich ueber die Grundlagen, Einsatzmoeglichkeiten und Anwendungsgebiete der Magnetlagertechnologie zu informieren. Im vorliegenden Tagungsband sind die von den Autoren eingereichten Beitraege in der Reihenfolge des Tagungsprogramms wiedergegeben. (orig.)

  19. Actively lubricated bearings applied as calibrated shakers to aid parameter identification in rotordynamics

    Santos, Ilmar; Cerda Varela, Alejandro Javier

    2013-01-01

    -invasive perturbation forces, or in other words, as a "calibrated shaker", to perform in-situ rotordynamic tests. The main original contributions of this paper are three: a) the experimental characterization of the active fluid film forces generated in an actively-lubricated tilting-pad journal bearing in the frequency......The servo valve input signal and the radial injection pressure are the two main parameters responsible for dynamically modifying the journal oil film pressure and generating active fluid film forces in controllable fluid film bearings. Such fluid film forces, resulting from a strong coupling...... domain and the application of such a controllable bearing as a calibrated shaker aiming at determining the frequency response function (FRF) of rotordynamic systems; b) experimental quantification of the influence of the supply pressure and servo valve input signal on the FRF of rotor-journal bearing...

  20. Linear and Non-Linear Control Techniques Applied to Actively Lubricated Journal Bearings

    Nicoletti, Rodrigo; Santos, Ilmar

    2003-01-01

    The main objectives of actively lubricated bearings are the simultaneous reduction of wear and vibration between rotating and stationary machinery parts. For reducing wear and dissipating vibration energy until certain limits, one can count with the conventional hydrodynamic lubrication....... For further reduction of shaft vibrations one can count with the active lubrication action, which is based on injecting pressurised oil into the bearing gap through orifices machined in the bearing sliding surface. The design and efficiency of some linear (PD, PI and PID) and non-linear controllers, applied...... vibration reduction of unbalance response of a rigid rotor, where the PD and the non-linear P controllers show better performance for the frequency range of study (0 to 80 Hz). The feasibility of eliminating rotor-bearing instabilities (phenomena of whirl) by using active lubrication is also investigated...

  1. Rotational Remanent Magnetization (RRM) to Identify Pyrrhotite in Natural Iron-Sulfide-Bearing Samples

    Slotznick, S. P.; Kirschvink, J. L.; Fischer, W. W.; Webb, S. M.

    2014-12-01

    Pyrrhotite has been known for several decades to have anomalous demagnetization behavior when using tumbling AF techniques. This was quantified by Thomson (1990) to show that pyrrhotite can acquire rotational remanent magnetization (RRM) similar to the more intensely-studied iron sulfide, greigite. Use of RRM as an identification tool in natural samples has not become standard practice, perhaps due to the decrease in use of tumbling AF techniques. However, using the 2G SQuID magnetometer with in-line AF/ARM coils and RAPID automated protocols (Kirschvink et al. 2008), one can easily produce and measure RRM. This method of measuring RRM has been used to identify greigite (Suzuki et al. 2006), but not pyrrhotite. We present room temperature RRM measurements for samples spinning from -20 to +20 rev/sec, perpendicular to peak AF fields of 90mT (at 950 Hz) in iron-sulfide-bearing shales, argillites, and carbonates throughout Earth History (Miocene, Cretaceous, Mesoproterozoic, Late Archean). Presence of pyrrhotite was confirmed using AF demagnetization of NRM (GRM), IRM acquisition/AF demagnetization (Cisowski plots), Kappabridge thermal susceptibility, ultra-high resolution scanning SQuID microscopy (UHRSSM), and/or X-ray absorption near edge spectroscopy (XANES)/multiple energy X-ray fluorescence (XRF) imaging. Although the total absence of pyrrhotite cannot be proven, the same techniques were applied to rocks that do not gain RRM easily to identify their iron sulfides and ferromagnetic minerals, and no magnetic iron sulfides were found. The RRM signal for pyrrhotite is distinct from that of greigite, suggesting it could be used as a tool for distinguishing these magnetic iron sulfides from each other. Further work on room temperature RRM could define a unique non-destructive rock magnetic test for pyrrhotite.

  2. Test equipment for a flywheel energy storage system using a magnetic bearing composed of superconducting coils and superconducting bulks

    Ogata, M.; Matsue, H.; Yamashita, T.; Hasegawa, H.; Nagashima, K.; Maeda, T.; Matsuoka, T.; Mukoyama, S.; Shimizu, H.; Horiuchi, S.

    2016-05-01

    Energy storage systems are necessary for renewable energy sources such as solar power in order to stabilize their output power, which fluctuates widely depending on the weather. Since ‘flywheel energy storage systems’ (FWSSs) do not use chemical reactions, they do not deteriorate due to charge or discharge. This is an advantage of FWSSs in applications for renewable energy plants. A conventional FWSS has capacity limitation because of the mechanical bearings used to support the flywheel. Therefore, we have designed a superconducting magnetic bearing composed of a superconducting coil stator and a superconducting bulk rotor in order to solve this problem, and have experimentally manufactured a large scale FWSS with a capacity of 100 kWh and an output power of 300 kW. The superconducting magnetic bearing can levitate 4 tons and enables the flywheel to rotate smoothly. A performance confirmation test will be started soon. An overview of the superconducting FWSS is presented in this paper.

  3. Magnetic polarity ages of the fossil-bearing strata at the Si hetun section, West Liaoning:A preliminary result

    2001-01-01

    Rock-magnetic and palaeomagnetic studies have been carried out on the interval of famous fossil-bearing sedimentary rocks and its overlying basalts and underlying basalts at the Sihetun section, West Liaoning Province. Normal polarity was obtained for the sedimentary interval and the underlying basalts, while reversed polarity was found in the overlying basalts. Taking account of the new 40Ar/39Ar ages (Swisher et al., 1999), we classified the fossil-bearing sedimentary interval into the Barremian M3n zone (Early Cretaceous age). Several abnormal horizons on magnetic properties, probably corresponding to the tuffs,were observed in the fossil-bearing sedimentary interval.This implies that the massive bio-extinction may link to dramatic environmental changes that were caused by voleanic eruptions.``

  4. Magnetization behavior of RE123 bulk magnets bearing twin seed-crystals in pulsed field magnetization processes

    Oka, T.; Miyazaki, T.; Ogawa, J.; Fukui, S.; Sato, T.; Yokoyama, K.; Langer, M.

    2016-02-01

    Melt-textured Y-Ba-Cu-O high temperature superconducting bulk magnets were fabricated by the cold seeding method with using single or twin-seed crystals composed of Nd-Ba-Cu-O thin films on MgO substrates. The behavior of the magnetic flux penetration into anisotropic-grown bulk magnets thus fabricated was precisely evaluated during and after the pulsed field magnetization operated at 35 K. These seed crystals were put on the top surfaces of the precursors to grow large grains during the melt-processes. Although we know the magnetic flux motion is restricted by the enhanced pinning effect in temperature ranges lower than 77 K, we observed that flux invasion occurred at applied fields of 3.3 T when the twin seeds were used. This is definitely lower than those of 3.7 T when the single-seeds were employed. This means that the magnetic fluxes are capable of invading into twin-seeded bulk magnets more easily than single-seeded ones. The twin seeds form the different grain growth regions, the narrow-GSR (growth sector region) and wide-GSR, according to the different grain growth directions which are parallel and normal to the rows of seed crystals, respectively. The invading flux measurements revealed that the magnetic flux invades the sample from the wide-GSR prior to the narrow-GSR. It suggests that such anisotropic grain growth leads to different distributions of pinning centers, variations of J c values, and the formation of preferential paths for the invading magnetic fluxes. Using lower applied fields definitely contributed to lowering the heat generation during the PFM process, which, in turn, led to enhanced trapped magnetic fluxes.

  5. Exploring integral controllers in actively-lubricated tilting-pad journal bearings

    Salazar, Jorge Andrés González; Santos, Ilmar

    2015-01-01

    Active tilting-pad journal bearings with radial oil injection combine good stability properties of conventional tilting-pad journal bearings with the capability of improving their dynamic properties even more by control techniques. The main contribution of this work is the experimental...... investigation of integral controllers for feedback-controlled lubrication with the aim of: a) presetting the static journal center and consequently exploring the changes of bearing dynamic properties; b) obtaining an integral controller capable of re-positioning the static journal eccentricity for matching...... equilibria under conventional hydrodynamic and feedback-controlled lubrication regimes. A novel application is proposed, that tries to build non-invasive perturbation forces and uses the active fluid film forces of the bearing as a calibrated shaker....

  6. Textured bearing surface in artificial joints to reduce macrophage activation

    Nakanishi, Yoshitaka; Nishi, Naoki; Chikaura, Hiroto; Nakashima, Yuta; Miura, Hiromasa; Higaki, Hidehiko; Mizuta, Hiroshi; Iwamoto, Yukihide; Fujiwara, Yukio; Komohara, Yoshihiro; Takeya, Motohiro

    2015-12-01

    Micro slurry-jet erosion has been proposed as a precision machining technique for the bearing surfaces of artificial joints in order to reduce the total amount of polyethylene wear and to enlarge the size of the wear debris. The micro slurry-jet erosion method is a wet blasting technique which uses alumina particles as the abrasive medium along with compressed air and water to create an ideal surface. Pin-on-disc wear tests with multidirectional sliding motion on the textured surface of a \\text{Co}-\\text{Cr}-\\text{Mo} alloy counterface for polyethylene resulted in both a reduction of wear as well as enlargement of the polyethylene debris size. In this study, primary human peripheral blood mononuclear phagocytes were incubated with the debris, and it was elucidated that the wear debris generated on the textured surface regulated secretion of the proinflammatory cytokines IL-6 and TNF-α, indicating a reduction in the induced tissue reaction and joint loosening.

  7. Synthesis of New Thiazole Derivatives Bearing A Sulfonamide Moiety Of Expected Anticancer And Radiosensitizing Activities

    In a search for new cytotoxic agents with improved antitumor activity and selectivity, some new pyrano thiazole and thiazolopyranopyrimidine derivatives bearing sulfonamide moiety were synthesized. The newly synthesized compounds were evaluated for their antitumor activity alone and in combination with γ-irradiation. These new compounds were docked inside the active site of carbonic anhydrase II to predict their mechanism of action.

  8. Diffusion in active magnetic colloids

    Properties of active colloids of circle swimmers are reviewed. As a particular example of active magnetic colloids the magnetotactic bacteria under the action of a rotating magnetic field is considered. The relation for a diffusion coefficient due to the random switching of the direction of rotation of their rotary motors is derived on the basis of the master equation. The obtained relation is confirmed by the direct numerical simulation of random trajectory of a magnetotactic bacterium under the action of the Poisson type internal noise due to the random switching of rotary motors. The results obtained are in qualitative and quantitative agreement with the available experimental results and allow one to determine the characteristic time between the switching events of a rotary motor of the bacterium. - Highlights: • Magnetotactic bacteria in a rotating field behaves as circle swimmers. • Diffusion coefficient of these swimmers due to the random switching of rotary motors is calculated. • Results are in good qualitative and quantitative agreement with available experimental results

  9. Linear and non-linear control techniques applied to actively lubricated journal bearings

    Nicoletti, R.; Santos, I. F.

    2003-03-01

    The main objectives of actively lubricated bearings are the simultaneous reduction of wear and vibration between rotating and stationary machinery parts. For reducing wear and dissipating vibration energy until certain limits, one can use the conventional hydrodynamic lubrication. For further reduction of shaft vibrations one can use the active lubrication action, which is based on injecting pressurized oil into the bearing gap through orifices machined in the bearing sliding surface. The design and efficiency of some linear (PD, PI and PID) and a non-linear controller, applied to a tilting-pad journal bearing, are analysed and discussed. Important conclusions about the application of integral controllers, responsible for changing the rotor-bearing equilibrium position and consequently the "passive" oil film damping coefficients, are achieved. Numerical results show an effective vibration reduction of unbalance response of a rigid rotor, where the PD and the non-linear P controllers show better performance for the frequency range of study (0-80 Hz). The feasibility of eliminating rotor-bearing instabilities (phenomena of whirl) by using active lubrication is also investigated, illustrating clearly one of its most promising applications.

  10. Study on the controllability for active magnetic bearings

    One of the main challenges in AMB is its controllability which means it is difficult to get a stable spindle and controller. To solve this problem, some methods have been developed previously, but the value of the controllability of AMB was not calculated. The subject of our study is to develop a new method and find a mathematical model that aims to research the controllability of AMB, the status at passing through levitation process, running, a critical speed and achieve high-speed rotation. The stiffness and damping of AMB, which changes randomly along with the rotor running, are determined by the controller system. How to get the relationship between the stiffness and damping with dynamic coefficients of rotor-AMB system is a key problem to get an optimization controller. In this paper, a mathematical model of the relationship is established. Stiffness and damping of AMB can change if the parameter of controller modulated. Based on rotor dynamics theory, the dynamic characteristics of rotors such as critical speeds, system stability and unbalanced excitation are analyzed. Computer simulations are carried out and the effectiveness of the presented procedure is investigated

  11. Magnetic Helicity Injection in Solar Active Regions

    Hong-Qi Zhang

    2006-01-01

    We present the evolution of magnetic field and its relationship with magnetic (current) helicity in solar active regions from a series of photospheric vector magnetograms obtained by Huairou Solar Observing Station, longitudinal magnetograms by MDI of SOHO and white light images of TRACE. The photospheric current helicity density is a quantity reflecting the local twisted magnetic field and is related to the remaining magnetic helicity in the photosphere, even if the mean current helicity density brings the general chiral property in a layer of solar active regions. As new magnetic flux emerges in active regions, changes of photospheric current helicity density with the injection of magnetic helicity into the corona from the subatmosphere can be detected, including changes in sign caused by the injection of magnetic helicity of opposite sign. Because the injection rate of magnetic helicity and photospheric current helicity density have different means in the solar atmosphere,the injected magnetic helicity is probably not proportional to the current helicity density remaining in the photosphere. The evidence is that rotation of sunspots does not synchronize exactly with the twist of photospheric transverse magnetic field in some active regions (such as, delta active regions). They represent different aspects of magnetic chirality. A combined analysis of the observational magnetic helicity parameters actually provides a relative complete picture of magnetic helicity and its transfer in the solar atmosphere.

  12. Development and characterization of magnetic iron oxide nanoparticles with a cisplatin-bearing polymer coating for targeted drug delivery

    Unterweger, Harald; Tietze, Rainer; Janko, Christina; Zaloga, Jan; Lyer, Stefan; Dürr, Stephan; Taccardi, Nicola; Goudouri, Ourania-Menti; Hoppe, Alexander; Eberbeck, Dietmar; Schubert, Dirk W; Boccaccini, Aldo R; Alexiou, Christoph

    2014-01-01

    A highly selective and efficient cancer therapy can be achieved using magnetically directed superparamagnetic iron oxide nanoparticles (SPIONs) bearing a sufficient amount of the therapeutic agent. In this project, SPIONs with a dextran and cisplatin-bearing hyaluronic acid coating were successfully synthesized as a novel cisplatin drug delivery system. Transmission electron microscopy images as well as X-ray diffraction analysis showed that the individual magnetite particles were around 4.5 nm in size and monocrystalline. The small crystallite sizes led to the superparamagnetic behavior of the particles, which was exemplified in their magnetization curves, acquired using superconducting quantum interference device measurements. Hyaluronic acid was bound to the initially dextran-coated SPIONs by esterification. The resulting amide bond linkage was verified using Fourier transform infrared spectroscopy. The additional polymer layer increased the vehicle size from 22 nm to 56 nm, with a hyaluronic acid to dextran to magnetite weight ratio of 51:29:20. A maximum payload of 330 μg cisplatin/mL nanoparticle suspension was achieved, thus the particle size was further increased to around 77 nm with a zeta potential of −45 mV. No signs of particle precipitation were observed over a period of at least 8 weeks. Analysis of drug-release kinetics using the dialysis tube method revealed that these were driven by inverse ligand substitution and diffusion through the polymer shell as well as enzymatic degradation of hyaluronic acid. The biological activity of the particles was investigated in a nonadherent Jurkat cell line using flow cytometry. Further, cell viability and proliferation was examined in an adherent PC-3 cell line using xCELLigence analysis. Both tests demonstrated that particles without cisplatin were biocompatible with these cells, whereas particles with the drug induced apoptosis in a dose-dependent manner, with secondary necrosis after prolonged incubation

  13. Connection between active longitudes and magnetic helicity

    Brandenburg, A

    2005-01-01

    A two-dimensional mean field dynamo model is solved where magnetic helicity conservation is fully included. The model has a negative radial velocity gradient giving rise to equatorward migration of magnetic activity patterns. In addition the model develops longitudinal variability with activity patches travelling in longitude. These patches may be associated with active longitudes.

  14. Compensation of Cross-Coupling Stiffness and Increase of Direct Damping in Multirecess Journal Bearings using Active Hybrid Lubrication

    Santos, Ilmar; Watanabe, F.Y.

    2004-01-01

    Fluid film forces are generated in hydrostatic journal bearings by two types of lubrication mechanisms: the hydrostatic lubrication in the bearing recesses and hydrodynamic lubrication in the bearing lands, when operating in rotation. The combination of both lubrication mechanisms leads to hybrid...... journal bearings (HJB). When part of hydrostatic pressure is also dynamically modified by means of hydraulic control systems, one refers to the active lubrication. The main contribution of the present theoretical work is to show that it is possible to reduce cross-coupling stiffness and increase the...... direct damping coefficients by means of the active lubrication, what leads to rotor-bearing systems with larger threshold of stability....

  15. Tunable reflector with active magnetic metamaterials.

    Deng, Tianwei; Huang, Ruifeng; Tang, Ming-Chun; Tan, Peng Khiang

    2014-03-24

    We placed active magnetic metamaterials on metallic surface to implement a tunable reflector with excellent agile performance. By incorporating active elements into the unit cells of the magnetic metamaterial, this active magnetic metamaterial can be tuned to switch function of the reflector among a perfect absorber, a perfect reflector and a gain reflector. This brings about DC control lines to electrically tune the active magnetic metamaterial with positive loss, zero loss and even negative loss. The design, analytical and numerical simulation methods, and experimental results of the tunable reflector are presented. PMID:24663977

  16. Demagnetizing fields in active magnetic regenerators

    Nielsen, Kaspar Kirstein; Bahl, Christian R.H.; Smith, Anders

    2014-01-01

    A magnetic material in an externally applied magnetic field will in general experience a spatially varying internal magnetic field due to demagnetizing effects. When the performance of active magnetic regenerators (AMRs) is evaluated using numerical models the internal field is often assumed to be...... is in general both a function of the overall shape of the regenerator and its morphology (packed particles, parallel plates etc.) as well as the magnetization of the material. Due to the pronounced temperature dependence of the magnetization near the Curie temperature, the demagnetization field is...

  17. Modeling and Development of a Magnetic Bearing Controller for a High Speed Flywheel System

    Dever, Timothy P.; Brown, Gerald V.; Duffy, Kirsten P.; Jansen, Ralph H.

    2005-01-01

    This paper describes a modeling effort used to develop an improved type of magnetic bearing controller, called a modal controller, for use on high speed flywheel systems. The controller design is based on models of the flywheel system, is designed to directly control the natural dynamics of the spinning rotor, and is generic enough to be readily adapted to future flywheel systems. Modeling and development are described for two key controller subsystems: the modal controller subsystem, which allows direct control over the rotor rigid body modes, and the bending mode compensation subsystem, which tracks, and prevents interference from, the rotor bending modes during flywheel operation. Integration of modeling results into the final controller is described and data taken on the NASA Glenn D1 flywheel module during high speed operation are presented and discussed. The improved modal controller described in this paper has been successfully developed and implemented and has been used for regular hands-free operation of the D1 flywheel module up to its maximum operating speed of 60,000 RPM.

  18. Frequency Response Analysis of an Actively Lubricated Rotor/Tilting-Pad Bearing System

    Nicoletti, Rodrigo; Santos, Ilmar

    2005-01-01

    In the present paper the dynamic response of a rotor supported by an active lubricated tilting-pad bearing is investigated in the frequency domain. The theoretical part of the investigation is based on a mathematical model obtained by means of rigid body dynamics. The oil film forces are inserted...... active lubricated tilting-pad bearing. By applying a simple proportional controller it is possible to reach 30% reduction of the resonance peak associated with the first rigid body mode shape of the system. One of the most important consequences of such a vibration reduction in rotating machines is the...

  19. Superconducting magnet activities at CEN Saclay

    The activities in superconducting magnets at DPhPE/Saclay spread over a wide range from DC magnets mainly for particle and nuclear physics and also for other fields of research, pulsed magnets for particle accelerators and for a controlled fusion tokamak machine. The superconducting magnets designed during recent years involve a variety of conductor types, winding schemes, materials and cooling modes, including the use of superfluid helium. (author)

  20. Pumps for cryogenic liquids with superconducting magnetic bearings. Final report; Pumpen fuer kryogene Fluessigkeiten mit supraleitenden Magnetlagern. Abschlussbericht

    Gerlach, G.; Fuchs, G.; Sorber, J.; Brosche, H.; Richter, M.; Frenzel, C.

    2000-07-01

    A liquid nitrogen pump with contactless superconducting magnetic bearings was to be developed on the basis of an available motor with superconducting bearings. Contactless superconducting magnetic bearings require practically no servicing. A high demand for pumps for cryogenic liquids is expected with the impending use of hydrogen as an energy source. The pumping of liquid nitrogen was demonstrated successfully with the new test aggregate. The maximum pumped volume was 17 l/min at a lift of 0.5 m and 6 l/min at a lift of 1 m. In all, 15 hours of operation were registered in the superconducting state of the bearing, which included 2 hours of uninterrupted pump operation. The higher speed range for which magnetic bearings are optimally suited was not reached. Operation at higher frequencies was impossible either because of stronger resonance amplituees or because the power system was too weak. [German] Ziel des Vorhabens war die Entwicklung einer Pumpe fuer fluessigen Stickstoff mit beruehrungslosen supraleitenden Magnetlagern auf der Basis eines vorhandenen supraleitend gelagerten Motors. Die beruehrungslose supraleitende Magnetlager sind praktisch wartungsfrei. Ein Bedarf an Pumpen fuer kryogene Fluessigkeiten entsteht insbesondere durch den in naher Zukunft zu erwartenden Einsatz von Wasserstoff als Energietraeger. Mit dem entworfenen Aggregat wurde das Pumpen von Fluessigstickstoff erfolgreich demonstriert. Der Foerderstrom betrug bei 0,5m Foerderhoehe maximal 17 l/min; beim 1m Foerderhoehe wurden maximal 6 l/min gemessen. Es wurden insgesamt ca. 15 Betriebsstunden in supraleitenden Zustand des Lagers, darunter 2 Stunden ununterbrochener Pumpbetrieb registriert. Der hoehere Drehzahlbereich, fuer den das Magnetlager eigentlich paedestiniert ist, konnte nicht erreicht werden. Ein Betrieb bei hoeheren (Ist-)Frequenzen war nicht moeglich, entweder durch staerkere Resonanzausschlaege oder durch einen zu schwachen Antrieb. (orig.)

  1. Active lubrication applied to radial gas journal bearings. Part 2: Modelling improvement and experimental validation

    Pierart, Fabián G.; Santos, Ilmar F.

    2016-01-01

    Actively-controlled lubrication techniques are applied to radial gas bearings aiming at enhancing one of their most critical drawbacks, their lack of damping. A model-based control design approach is presented using simple feedback control laws, i.e. proportional controllers. The design approach...... combines three main domains: tribology, dynamics and control. The Reynolds equation with radial injection, including piezoelectrically controlled jet, describes the non-linear interaction between bearing surface and rotating shaft. Dynamics of the flexible shaft and rotating parts are modelled aid by...... finite element method and the global model is used as control design tool. Active lubrication allows for significant increase in damping factor of the rotor-bearing system. Very good agreement between theory and experiment is obtained, supporting the multi-physic design tool developed....

  2. Actively lubricated bearings applied as calibrated shakers to aid parameter identification in rotordynamics

    Santos, Ilmar; Cerda Varela, Alejandro Javier

    2013-01-01

    between hydrodynamic, hydrostatic and controllable lubrication regimes, can be used either to control or to excite rotor lateral vibrations. An accurate characterization of the active oil film forces is of fundamental importance to elucidate the feasibility of applying the active lubrication as non......-invasive perturbation forces, or in other words, as a "calibrated shaker", to perform in-situ rotordynamic tests. The main original contributions of this paper are three: a) the experimental characterization of the active fluid film forces generated in an actively-lubricated tilting-pad journal bearing in the frequency...... systems; c) experimental indication of how small such active fluid film forces (perturbation forces) should be, in order to perturb the rotor-journal bearing system without significantly changing its dynamic characteristics. To validate the experimental procedure and results obtained via actively-lubricated...

  3. Thermally activated magnetization reversal in magnetic tunnel junctions

    Zhou Guang-Hong; Wang Yin-Gang; Qi Xian-Jin; Li Zi-Quan; Chen Jian-Kang

    2009-01-01

    In this paper, the magnetization reversal of the ferromagnetic layers in the lrMn/CoFe/AlOx/CoFe magnetic tunnel junction has been investigated using bulk magnetometry. The films exhibit very complex magnetization processes and reversal mechanism. Thermal activation phenomena such as the training effect, the asymmetry of reversal, the loop broadening and the decrease of exchange field while holding the film at negative saturation have been observed on the hysteresis loops of the pinned ferromagnetic layer while not on those of the free ferromagnetic layer. The thermal activation phenomena observed can be explained by the model of two energy barrier distributions with different time constants.

  4. Water-soluble ruthenium complexes bearing activity against protozoan parasites.

    Sarniguet, Cynthia; Toloza, Jeannette; Cipriani, Micaella; Lapier, Michel; Vieites, Marisol; Toledano-Magaña, Yanis; García-Ramos, Juan Carlos; Ruiz-Azuara, Lena; Moreno, Virtudes; Maya, Juan Diego; Azar, Claudio Olea; Gambino, Dinorah; Otero, Lucía

    2014-06-01

    Parasitic illnesses are major causes of human disease and misery worldwide. Among them, both amebiasis and Chagas disease, caused by the protozoan parasites, Entamoeba histolytica and Trypanosoma cruzi, are responsible for thousands of annual deaths. The lack of safe and effective chemotherapy and/or the appearance of current drug resistance make the development of novel pharmacological tools for their treatment relevant. In this sense, within the framework of the medicinal inorganic chemistry, metal-based drugs appear to be a good alternative to find a pharmacological answer to parasitic diseases. In this work, novel ruthenium complexes [RuCl2(HL)(HPTA)2]Cl2 with HL=bioactive 5-nitrofuryl containing thiosemicarbazones and PTA=1,3,5-triaza-7-phosphaadamantane have been synthesized and fully characterized. PTA was included as co-ligand in order to modulate complexes aqueous solubility. In fact, obtained complexes were water soluble. Their activity against T. cruzi and E. histolytica was evaluated in vitro. [RuCl2(HL4)(HPTA)2]Cl2 complex, with HL4=N-phenyl-5-nitrofuryl-thiosemicarbazone, was the most active compound against both parasites. In particular, it showed an excellent activity against E. histolytica (half maximal inhibitory concentration (IC50)=5.2 μM), even higher than that of the reference drug metronidazole. In addition, this complex turns out to be selective for E. histolytica (selectivity index (SI)>38). The potential mechanism of antiparasitic action of the obtained ruthenium complexes could involve oxidative stress for both parasites. Additionally, complexes could interact with DNA as second potential target by an intercalative-like mode. Obtained results could be considered a contribution in the search for metal compounds that could be active against multiple parasites. PMID:24740394

  5. The Magnetic Free Energy in Active Regions

    Metcalf, Thomas R.; Mickey, Donald L.; LaBonte, Barry J.

    2001-01-01

    The magnetic field permeating the solar atmosphere governs much of the structure, morphology, brightness, and dynamics observed on the Sun. The magnetic field, especially in active regions, is thought to provide the power for energetic events in the solar corona, such as solar flares and Coronal Mass Ejections (CME) and is believed to energize the hot coronal plasma seen in extreme ultraviolet or X-rays. The question remains what specific aspect of the magnetic flux governs the observed variability. To directly understand the role of the magnetic field in energizing the solar corona, it is necessary to measure the free magnetic energy available in active regions. The grant now expiring has demonstrated a new and valuable technique for observing the magnetic free energy in active regions as a function of time.

  6. Feasibility of Influencing the Dynamic Fluid Film Coefficients of a Multirecess Journal Bearing by means of Active Hybrid Lubrication

    Santos, Ilmar; Watanabe, F. Y.

    2003-01-01

    The main objective of this research project is the investigation of multirecess hydrostatic journal bearings with active hybrid (hydrostatic and hydrodynamic) lubrication. This paper gives a theoretical contribution to the modeling of this kind of bearing, combining computational fluid dynamics a...... significant modifications of active hybrid forces, which can be useful while reducing vibration and stabilizing rotating machines.......The main objective of this research project is the investigation of multirecess hydrostatic journal bearings with active hybrid (hydrostatic and hydrodynamic) lubrication. This paper gives a theoretical contribution to the modeling of this kind of bearing, combining computational fluid dynamics and...

  7. Frequency Response Analysis of an Actively Lubricated Rotor/Tilting-Pad Bearing System

    Nicoletti, Rodrigo; Santos, Ilmar

    2004-01-01

    In the present paper, the dynamic response of a rotor supported by an active lubricated tilting-pad bearing is investigated in the frequency domain. The theoretical part of the investigation is based on a mathematical model obtained by means of rigid body dynamics. The oil film forces are inserted...... lubricated tilting-pad bearing. By applying a simple proportional controller, it is possible to reach 30% reduction of the resonance peak associated with the first rigid body mode shape of the system. One of the most important consequences of such a vibration reduction in rotating machines is the feasibility...

  8. Experimental Identification of Dynamic Coefficients of Tilting-Pad Bearings with Active Lubrication

    Salazar, Jorge Andrés González; Cerda Varela, Alejandro Javier; Santos, Ilmar

    supply unit, b) servovalves, c) radial injection nozzles, d) displacement sensors and e) well-tuned digital controllers which turn the bearing static and dynamic properties controllable. A scaled-down industrial rotor, composed by a flexible rotor supported by a four rocker LBP tilting-pad journal......This article presents the experimental identification of the equivalent dynamic coefficients of an activelylubricated bearing under different lubrication regimes, namely: passive (no injection flow), hybrid (constant injection flow) and feedback-controlled (variable injection flow) lubrication. The...... bearing featuring active lubrication under light load conditions, is used for such a goal. The experimental identification is performed in the frequency domain by means of the measured FRFs and a finite element model of the rotor. The comparison between results under the different lubrication regimes...

  9. Development and characterization of magnetic iron oxide nanoparticles with a cisplatin-bearing polymer coating for targeted drug delivery

    Unterweger H

    2014-08-01

    Full Text Available Harald Unterweger,1 Rainer Tietze,1 Christina Janko,1 Jan Zaloga,1 Stefan Lyer,1 Stephan Dürr,1 Nicola Taccardi,2 Ourania-Menti Goudouri,3 Alexander Hoppe,3 Dietmar Eberbeck,4 Dirk W Schubert,5 Aldo R Boccaccini,3 Christoph Alexiou1 1ENT Department, Section of Experimental Oncology and Nanomedicine (SEON, Else Kroener-Fresenius-Stiftung-Professorship, University Hospital Erlangen, 2Chair of Chemical Engineering I (Reaction Engineering, 3Institute of Biomaterials, Department of Materials Science and Engineering, University Erlangen-Nuremberg, Erlangen, 4Physikalisch-Technische Bundesanstalt, Berlin, 5Institute of Polymer Materials, Department of Materials Science and Engineering, University Erlangen-Nuremberg, Erlangen, Germany Abstract: A highly selective and efficient cancer therapy can be achieved using magnetically directed superparamagnetic iron oxide nanoparticles (SPIONs bearing a sufficient amount of the therapeutic agent. In this project, SPIONs with a dextran and cisplatin-bearing hyaluronic acid coating were successfully synthesized as a novel cisplatin drug delivery system. Transmission electron microscopy images as well as X-ray diffraction analysis showed that the individual magnetite particles were around 4.5 nm in size and monocrystalline. The small crystallite sizes led to the superparamagnetic behavior of the particles, which was exemplified in their magnetization curves, acquired using superconducting quantum interference device measurements. Hyaluronic acid was bound to the initially dextran-coated SPIONs by esterification. The resulting amide bond linkage was verified using Fourier transform infrared spectroscopy. The additional polymer layer increased the vehicle size from 22 nm to 56 nm, with a hyaluronic acid to dextran to magnetite weight ratio of 51:29:20. A maximum payload of 330 µg cisplatin/mL nanoparticle suspension was achieved, thus the particle size was further increased to around 77 nm with a zeta

  10. Absolute alpha activity measurements of some plants growing in monazite bearing soils in Sri Lanka

    Mahawatte, P.; Hewamanna, R. (Colombo Univ. (Sri Lanka). Radioisotope Centre)

    1991-01-01

    Deposits of monazite bearing soils occur along the Southwest, West and East Coasts of Sri Lanka. High levels of gamma activity in some plant species growing in the West Coast have been reported. The high levels were due to the presence of the daughter nuclides of {sup 232}Th, most of which are alpha emitters. Absolute alpha activity measurements of ash samples of some plants growing in monazite bearing soils were carried out using the alpha sensitive polymeric nuclear track detector CR-39. The values ranged from 60-1900 mBq/g and were in good agreement with the values obtained from conventional scintillation counting method. The activity concentration of {sup 228}Th in the ash samples was also calculated by measuring the activity concentration of emanated thoron trapped inside a glass bottle with the use of a CR-39 track detector. (author).