• Journal of Power System Engineering
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• v.1 no.1
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• pp.144-153
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• 1997

The magnetic levitation system is utilized in the magnetic bearing of high-speed rotor because of little friction, no lubrication, no noise and so on. The magnetic levitation system need the feedback controller for the stabilization of system, and gap sensors are generally used to measure the gap. The use of gap sensors brings out the increase of the number of troublesome, and the decrease of the control performance because of the dislocation between the measurement point and the control point. This paper presents the design of the gap estimation circuit for the sensorless method proposed by authors in the magnetic levitation system. We made the gap estimation circuit which was composed of both the superposition circuit and the measuring circuit. And we investigated the validity of the usefulness of the proposed sensorless method in the magnetic levitation system through results of actual experiment.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.12
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• pp.41-47
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• 2009

In this paper, authors performed improvement of control characteristics of an attraction type magnetic levitation system. The attraction type magnetic levitation system has an inherent instability in the system, therefore its controller must have not only proportional-integral gain but also differential gain additionally. In this paper, authors were proposed control algorithm using disturbance observer(DOB) on feedback signal. The computer simulation and experiments were performed for its verification.

• Proceedings of the Materials Research Society of Korea Conference
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• 2012.05a
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• pp.93.1-93.1
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• 2012

세라믹 고온초전도체는 에너지 저장장치의 핵심소재로 사용된다. 초전도 플라이휠 에너지 저장장치(Superconductor flywheel energy storage system)는 전기 에너지를 운동 에너지로 변환하여 저장하는 친환경, 고효율 에너지 저장장치이다. 에너지를 최소화하는데 사용되는 초전도 베어링은 고온초전도체와 영구자석으로 구성된다. 베어링에는 희토류계 초전도 물질(RE-Ba-Cu-O, RE:Rare-earth elements)가 사용된다. 베어링의 효율은 영구자석의 자력크기, 초전도체의 자기부상력과 포획자력에 비례한다. 에너지 저장효율을 높이려면 고온 초전도체의 임계전류밀도(초전도체 내부에 흘릴 수 있는 전기량)를 높이고, 초전도 결정립의 크기를 키워야 한다. 결정크기를 키우는 공정으로 종자결정성장법(Seed growth process)이 사용된다. 초전도체 제조공정은 분말의 성형, incongruent melting을 포함하는 부분 용융, 액상에서의 입성장, 포정반응을 통한 초전도 결정의 성장과정을 포함한다. 본 발표에서는 초전도 에너지 저장장치의 기본 원리, 초전도 베어링의 구성, 베어링용 초전도체의 제조방법과 특성(자기부상력과 포획자력) 평가기술, 차세대 에너지 저장장치로서의 초전도 플라이휠 에너지 저장장치의 전망에 대해 요약하였다.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.17 no.11
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• pp.1077-1085
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• 2007

Typically, three types of levitation technologies are applied to magnetic levitation systems: electromagnetic suspension, electrodynamic suspension, and hybrid electromagnetic suspension. A Halbach array is a special arrangement of permanent magnets which augments the magnetic field on one side of the device while cancelling the field to near zero on the other side. The application of this Halbach array magnet to the electrodynamic suspension has been recently studied in order to increase the levitation capability. This paper is focused on an analytical method of the magnetic levitation system using Halbach array magnet. The suitability of the proposed method is verified with comparing to the finite element method. In addition, dynamic stability of the magnetic levitation system is discussed. From this study, it is confirmed that the proposed method provides a reasonable solution with less computation time compared to the finite element method and the magnetic levitation system using Halbach array magnet is stable dynamically.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.82-87
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• 2007

A Halbach array is a special arrangement of permanent magnets which augments the magnetic field on one side of the device while cancelling the field to near zero on the other side. The application of this Halbach array magnet to the electrodynamic suspension for Maglev train has been recently studied in order to increase the levitation capability. This paper is focused on analytical method of the magnetic levitation system using Halbach array magnet. The suitability of the proposed method is verified with comparing to a finite element method. From this study, it is confirmed that the proposed method provides a reasonable solution with a little analysis time to the finite element method and the magnetic levitation system using Halbach array magnet is stable dynamically.

• Journal of KSNVE
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• v.6 no.3
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• pp.357-362
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• 1996

The magnetic levitation system has great advantages, such as little friction, no lubrication, no noise and so on. But the magnetic levitation system need a stabilizing controller because it is a unstable, system in natural and it need a sensor for displacement measurement to control the system. In this paper, we proposed a sensorless method to measure the gap between the magnetic pole and the levitated object with application the inductance characteristic which vary according to gap. We made a driving circuit which supply simultaneously the control input PWM(Pulse Width Modulation) signal and the carrier PWM signal to estimate the gap. Because the inductance is a function of gap, and the current of the carrier signal is a function of the inductance, we could estimate the gap from the measurement of the current of the carrier signal. Finally, we investigated the validity of the proposed method through the experimental results.

• Journal of Power System Engineering
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• v.14 no.1
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• pp.65-70
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• 2010

Magnetic levitation system is nonlinear and inherently unstable, so it is difficult to control. Analog control circuit was widly used as the controller of magnetic levitation system, but digital controller is now substituted for analog controller according to development of digital electronics. In this study, Atmel AVR series, ATmega 128 which is a kind of $\mu$-processor for digital controller is used because the chip is cheap and popular. We designed and made ATmega 128 one-board controller and aimed to verify validity through the experiance of levitation response.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1038-1041
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• 2003

The magnetic suspension system is used in many areas, because it has great advantages. such as no friction, no noise, no lubrication and so on, but it is a unstable system in natural. It must have a feedback control with the position is measured for a stable levitation. There are an eddy-current sensor, a capacitive sensor, an inductive sensor, and an optical sensor with a laser as the sensor which measures displacements without contact. Among them, an inductive sensor is made with lower price than others. And it has a good linearity. In this paper, a magnetic circuit leads a linear equation between an input as a displacement and an output as a voltage. Experiments establish that voltage change according to displacement is linear. This paper presents the preliminary study of an inductive position sensing for self-sensing magnetic suspension system.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.10
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• pp.165-171
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• 1998

An axial electromagnetic levitation system using attractive force is a highly nonlinear system due to the nonlinearity of materials, variable air gap and flux density. To control the levitating system with large air gap, a conventional PID control based on the linear model is not satisfactory to obtain the desired performance and the position tracking control of the sinusoidal motion by simulation results. Thus, sliding mode control(SMC) based on the input-output linearization is suggested and evaluated by simulation and experimental approaches. Usefulness of the SMC to this system is conformed experimentally. If the expected variation of added mass can be included in the gain conditions and the model, the position control performance of the electromagnetic levitation system with large air gap will be improved with robustness.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1990.10a
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• pp.193-198
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• 1990

전자기 베어링은 기계적 접촉이 없고 전기적 제어가 가능하여 최근 고속 정 밀 회전기에 사용되고 있다. 본 논문에서는 능동 자기베어링을 모형화하고 제어 이득에 따른 계의 안정성 판별 및 응답특성의 변화를 고찰하였다. 이를 토대로 두개의 반경방향 베어링과 회전체를 제작하고 아날로그 제어회로를 구성하여 안정되게 회전체를 부상시킬수 있었으며 이로부터 계의 응답특성 을 구하였다.