• Title/Summary/Keyword: magnetic bearing

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Permanent Magnet Combined Thrust Magnetic Bearing Simulation and Experiment (영구자석조합형 축방향 자기베어링 시뮬레이션 및 실험)

  • Park, Byeong-Cheol;Jung, Se-Yong;Han, Sang-Chul;Lee, Jeong-Phil;Han, Young-Hee;Park, Byung-Jun
    • Tribology and Lubricants
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    • v.27 no.3
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    • pp.167-173
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    • 2011
  • In this paper, an actuator model of the thrust magnetic bearing for the flywheel energy storage is derived using magnetic circuit theory. And we compared this result with finite element magnetic field analysis result. Based on the actuator model, we made a simulation model of the thrust magnetic bearing system. We showed the closed loop transfer function and sensitivity function of the thrust magnetic bearing system using both the simulation model and the experiment. The experimental result at rotation velocity 18,000rpm of thrust magnetic bearing system is included.

A Six Pole Permanent Magnet Biased Homopolar Magnetic Bearing with Fault-Tolerant Capability

  • Uhn Joo Na
    • Journal of the Korean Society of Industry Convergence
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    • v.26 no.2_1
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    • pp.231-238
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    • 2023
  • This paper develops the theory for a novel fault-tolerant, permanent magnet biased, 6-active-pole, homopolar magnetic bearing. The Lagrange Multiplier optimization with equality constraints is utilized to calculate the optimal distribution matrices for the failed bearing. some numerical examples of distribution matrices are provided to illustrate the new theory. Simulations show that very much the same dynamic responses (orbits or displacements) are maintained throughout failure events (up to any combination of 3 coils failed for the 6 pole magnetic bearing) while currents and fluxes change significantly. The overall load capacity of the bearing actuator is reduced as coils fail. The same magnetic forces are then preserved up to the load capacity of the failed bearing.

A Study on the Identification and Robust Control of Flexible Rotor Supported by Magnetic Bearing (자기베어링으로 지지되는 연성축계의 식별 및 강인 제어에 관한 연구)

  • Ahn, H. J.;Jeon, S.;Han, D. C.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2000.11a
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    • pp.3-6
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    • 2000
  • The magnetic bearing system are intrinsically unstable, and need the feedback control of electromagnetic forces with measured displacements. So the controller design plays an important role in constructing high performance magnetic bearing system. In case of magnetic bearing system, the order of identified model is high because of unknown dynamics included in closed loop systems - such as sensor dynamics, actuator dynamics - and non-linearity of magnetic bearings itself. In this paper the identification and robust control of flexible rotor supported by magnetic bearing are discussed. We measure and identify overall system that contains not only flexible rotor model but also magnetic bearing and time delay. The structured and unstructured uncertainties are modeled that cover variations of natural frequencies, uncertainties in sensor and actuator gains and unmodeled dynamics. And desired performances are specified with several weighting function. Using augmented system that includes identified model, uncertainties, and weighting functions, μ-synthesis is applied to flexible rotor supported with magnetic bearing. The flexible rotor was spin up over the first flexible critical speed.

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Performance of Built-in Capacitance Type Transducer of a Magnetic Bearing System (캐패시턴스형 센서가 내장된 자기베어링 시스템의 작동성능에 관한 연구)

  • 장인배;한동철
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.19 no.9
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    • pp.2082-2088
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    • 1995
  • In this paper, we designed and fabricated the magnetic bearings and built-in type cylindrical capacitive transducers for improving the vibration characteristics of rotating shaft. The eddy current and magnetic field from the electromagnet of the bearing don't affect the measuring signal of the capacitive type transducers so that it is possible to locate the capacitive sensor plates around the magnetic bearing poles and can improve the spillover problem which is induced by the noncollocation of the sensors and actuators. According to the sensitivity calibration schemes using a X-Y table, the cylindrical capacitive transducers have a good linearities in the .+-.70.mu.m range from the geometric center of the sensor plates. The measured results also show high displacement sensitivities of the sensors. According to the performance test of the magnetic bearing which is controlled by the analog PD controllers, we found that the built-in capacitive transducer system successfully measures the journal displacement in the magnetic field and therefore the magnetic bearing system supports the rotating shaft up to 12,000 rpm.

A Robust Control of Horizontal-Shaft Magnetic Bearing System Using Linear Matrix Inequality Technique (선형행렬부등식 기법을 이용한 횡축형 자기 베어링 시스템의 로버스트 제어)

  • 김창화;정병건;양주호
    • Journal of Advanced Marine Engineering and Technology
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    • v.25 no.2
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    • pp.321-330
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    • 2001
  • Magnetic bearing system is frequently used for high-speed rotating machines because of its frictionless property. But the magnetic bearing system needs feedback controller for stabilization. This paper presents a robust controller design by using linear matrix inequality for magnetic bearing system which shows the control performance and robust stability under the physical parameter perturbations. To the end, the validity of the designed controller is investigated through computer simulation.

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A study on the Stiffness for a Radial Magnetic Bearing (반경방향 자기베어링의 강성에 관한 연구)

  • 김재실;안승국;이재환;안대균;최헌오
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 2002.04a
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    • pp.325-332
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    • 2002
  • This article describes (1) 2 and 3 dimensional electromagnetic finite element models for an active heteropolar radial magnetic bearing, (2) the procedure for obtaining the bearing stiffnesses by simulating the models and (3) the reviews of the models by comparing an experimental test to the ideal closed loop analysis with the stiffnesses calculated from (2). The 3 dimensional model for the magnetic bearing may be very effectively applied to several types of magnetic bearings.

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Design of Hybrid Superconductor Bearing Set for a Flywheel System with Vertical Axis (수직축형 플라이휠 시스템을 위한 초전도 하이브리드 베어링의 설계)

  • 이준성;한영희;한상철;성태현;김상준
    • Progress in Superconductivity and Cryogenics
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    • v.3 no.1
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    • pp.22-28
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    • 2001
  • A vortical axis flywheel system was conceptualized, which uses a hybrid superconductor bearing set to carry the wheel part load. The multiple designs of magnetic bearing and superconductor bearing were analyzed by using conventional numerical magnetostatic analysis method The best medels were selected among four different types of Permanent magnet bearings for upper bearing and two types of superconductor bearing for lower bearing, respectively These results were discussed in regard of application to the flywheel system with a Passive hybrid magnetic bearing set.

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Design of a Step Motor with a Passive Magnetic Bearing (수동형 마그네틱 베어링이 결합된 스텝 모터의 설계)

  • Kwak, Ho-Seong;Choi, Dong-Hoon;Kim, Seung-Jong
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.16 no.12 s.117
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    • pp.1201-1207
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    • 2006
  • This paper introduces a step motor with a passively levitated rotor which comprises a homopolar step motor and a passive magnetic bearing. Compared with conventional self-bearing motors which are mostly based on the active magnetic bearing technology, the proposed motor has a very simple structure and operating principle. For the levitation, it works just like passive magnetic bearings which use the repulsive force between permanent magnets. Halbach array is used to increase the bearing stiffness. On the other hand, its rotation principle is just the same with that of conventional motors. In this paper, we introduce the design scheme to avoid the flux interference possibly produced by electromagnets and permanent magnets, and show some results of FEM analysis to predict the performance of the proposed motor.

Robust Control of Disturbed Magnetic Bearing Rotor Systems (외란을 받는 자기베어링 주축계의 강건제어)

  • 강호식;송오섭
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.13 no.2
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    • pp.40-46
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    • 2004
  • Magnetic bearing has been adopted to support a rotor by electromagnetic force without mechanical contact and lubrication process. The recent growth of magnetic bearing applications in many industrial fields requires more accurate design of bearing-rotor system. Due to external forces and uncertainties of magnetic bearing system the actual performance and stability my be worse than it is designed. This paper describes the governing equations of rotor magnetic bearing systems and/or the designing of robust controller via standard $H_{\infty}$ control problem. The system stability and response characteristics are studied by simulations and verified with experimental results.

Design and Implementation of a Fault-Tolerant Magnetic Bearing System For Turbo-Molecular Vacuum Pump (터보분자펌프용 고장허용 자기베어링 시스템 설계 및 개발)

  • Cho, Sung-Rak;Noh, Myoung-Gyu;Park, Byung-Chul
    • Proceedings of the KSME Conference
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    • 2004.11a
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    • pp.760-765
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    • 2004
  • One of the obstacles for a magnetic bearing to be used in the wide range of industrial applications is the failure modes associated with magnetic bearings, which we don't expect for conventional passive bearings. These failure modes include electric power outage, power amplifier faults, position sensor faults, and the malfunction of controllers. Fault-tolerant magnetic bearing systems have been proposed so that the system can operate in spite of some faults in the system. In this paper, we designed and implemented a fault-tolerant magnetic bearing system for a turbo-molecular vacuum pump. The system can cope with the actuator/amplifier faults as well as the faults in position sensors, which are the two major fault modes in a magnetic bearing system.

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