• 한국반도체및디스플레이장비학회:학술대회논문집
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• 한국반도체및디스플레이장비학회 2004년도 춘계학술대회 발표 논문집
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• pp.179-184
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• 2004

This paper is an overview of the experimental work using a Planar Magnetic Levitation Stage System structure proposed by Dr. Won-Jong Kim in his PhD thesis. Based on his results, we built an Experimental Test Stand (ETS), which enabled us to get accustomed with the new technology and to create new control structures and algorithms. The ETS is controlled by a powerful controller made of 4 DSPs mastered by a PC. This controller structure increases the controller bandwidth up to 10 kHz leading to a better emulation of an analog controller and leaving enough room for further development. Based on analyzing all the factors that can affect the performances of the system, we achieved a great accurate positioning performance of sub-nanometer RMS value.

• Journal of Power Electronics
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• 제12권5호
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• pp.758-768
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• 2012

This paper presents the modeling and position-sensorless vector control of a dual-airgap axial flux permanent magnet (AFPM) machine optimized for use in flywheel energy storage system (FESS) applications. The proposed AFPM machine has two sets of three-phase stator windings but requires only a single power converter to control both the electromagnetic torque and the axial levitation force. The proper controllability of the latter is crucial as it can be utilized to minimize the vertical bearing stress to improve the efficiency of the FESS. The method for controlling both the speed and axial displacement of the machine is discussed. An inherent speed sensorless observer is also proposed for speed estimation. The proposed observer eliminates the rotary encoder, which in turn reduces the overall weight and cost of the system while improving its reliability. The effectiveness of the proposed control scheme has been verified by simulations and experiments on a prototype machine.

• 제어로봇시스템학회논문지
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• 제6권6호
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• pp.454-461
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• 2000

Electrostatic suspension offers an advantage of directly suspending various materials such as conductive materials, semiconductors and dielectric materials without any mechanical contacts. This is a specific feature compared with electromagnetic suspension which can suspend only ferro-magnetic material. In general, the electrostatic suspension systems require position sensors for stabilizing the suspended object. Therefore, a lot of displacement sensors and a switching circuit are required for moving the object through a long distance. In order to circumvent this problem, this paper proposes a self-sensing method which can provide the gap displacement between electrodes and suspended object without external sensors. Moreover a simple on-off controller is presented for stabilization. Experimental validation of the proposed scheme has been performed through the successful levitation of a 4-inch silicon wafer.

• 대한기계학회논문집
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• 제15권5호
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• pp.1620-1634
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• 1991

본 연구에서는 전기/자기 및 기계적 요소들이 복합되어 이루어진 자기부상 시 스템의 설현을 위한 기초단계로서 제어동역학(controlled dynamics) 측면에 입각한 모 델식을 본드선도 기법을 이용하여 보다 조직적으로 유도한다. 우선, 자속흐름 확장 및 자속 유출량을 고려하여 부상 시스템을 모델링하고 차량/레일 및 2차 현가(second ary suspension)장치를 포함한 자기부상 시스템을 모델링한다. 다음, 지지 및 안내 방향의 동역학을 동시에 고려한 2차원 자기부상 시스템을 본드선도의 다접점 필드(mu- ltiport field) 개념을 이용하여 모델링한다. 끝으로, 본드선도 기법으로 모델링된 2차원 자기부상 시스템의 안정도와 성능을 향상시키기 위하여 LOG/LTR(linear quadra- tic Gaussian control with loop transfer recovery) 제어시스템을 설계한다. LQG/ LTR 제어방법은 Doyle과 Stein에 의해 인성(stability-robustness) 문제와 주파수역 성능을 설계시에 직접 고려할 수 있는 강력한 선형 다변수 제어시스템 설곕방법으로 현재 널리 사용되고 있다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 추계학술대회 논문집
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• pp.1324-1329
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• 2007

For the commercialization of the urban maglev, an articulated turnout which consists of several segments of turnout girders and where switching is done by rotating those segments is under development. In this paper, to determine the alignment of this articulated turnout, the requirements for the alignement are analyzed. Requirements include: those for the levitation control and for the ride comfort. For the levitation control, rail joint width should be limited to a certain value, and for the ride comfort, the lateral acceleration and the time derivative of the lateral acceleration satisfy a guideline. According to these requirements, the alignment criteria are discussed.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제55권12호
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• pp.653-660
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• 2006

In this paper, dynamic simulation results for modules of a magnetically-levitated(Maglev) vehicle are presented. The mathematical dynamic models for the Maglev vehicle are firstly derived. The Maglev system consists of one vehicle, two half-bogies, one guideway, four secondary suspensions, eight electromagnets and levitation control systems. Also, the dynamic characteristics are analysed by using the derived models. Finally, two simulations such as reference airgap step change of 1mm and rail step change of 1mm, are carried out. The dynamic simulation results are shown to testify the developed dynamic simulation program. From the results, we can see the possibility of the dynamic simulation program to develop a new Maglev vehicle system.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 추계학술대회 논문집 학회본부 B
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• pp.499-501
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• 1998

In this paper, we present a self-compensating PID controller which consists of a conventional PID controller that controls the linear components and a neural controller that controls the higher order and nonlinear components. This controller is based on the Harris's concept where he explained that the adaptive controller consists of the PID control term and the disturbance compensating term. The resulting controller's architecture is also found to be very similar to that of Wang's controller. This controller adds a self-tuning ability to the existing PID controller without replacing it by compensating the control errors through the neuro-controller. When applied to an actual magnetic levitation system which is known to be very nonlinear, it has also produced an excellent results.

• 대한전기학회논문지:시스템및제어부문D
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• 제50권1호
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• pp.22-30
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• 2001

This paper describes a neural network based fuzzy PID control scheme. The PID controller is being widely used in industrial applications. However, it is difficult to determine the appropriated PID gains in nonlinear systems and systems with long time delay and so on. In this paper, we re-analyzed the fuzzy controller as conventional PID controller structure, and proposed a neural network based self tuning fuzzy PID controller of which output gains were adjusted automatically. The tuning parameters of the proposed controller were determined on the basis of the conventional PID controller parameters tuning methods. Then they were adjusted by using proposed neural network learning algorithm. Proposed controller was simple in structure and computational burden was small so that on-line adaptation was easy to apply to. The experiment on the magnetic levitation system, which is known to be heavily nonlinear, showed the proposed controller's excellent performance.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 B
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• pp.1327-1329
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• 2005

This paper presents a gam optimization method using genetic algorithm(GA) for a magnetic levitation(Maglev) controller. GA uses the integral of square error(ISE) as performance index. The plant dynamics are described and modelled by mathematical equations. Also, the system apparatus for the Maglev system are described. Using the derived model, to optimize the feedback gains of conventional state feedback controller(SFC), GA is simulated with SIMULINK model. finally, using the optimized feedback gains, SFC is applied to the Maglev system. From the results, we can see that GA can give a solution for the better control performance for the Maglev system.

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2008년도 Asian Magnetics Conference
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• pp.213.1-213.1
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• 2008