• Journal of international Conference on Electrical Machines and Systems
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• v.2 no.1
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• pp.40-44
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• 2013

This paper presents a design and characteristics analysis of novel 2-phase 4/3 switched reluctance motor (SRM) with short flux path for an air-blower application. The desired air-blower is unidirectional application, and requires a wide positive torque region without torque dead-zone. In order to get a wide positive torque region without torque dead-zone during phase commutation, asymmetric inductance characteristic with non-uniform air-gap is considered. The proposed motor could be started at any rotor position with high efficiency drive. The proposed 2-phase 4/3 SRM is verified by finite element method analysis.

• Journal of Institute of Control, Robotics and Systems
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• v.12 no.7
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• pp.658-665
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• 2006

RVDT is a transducer that presents rotary phase angle according to the displacement of eccentric rotor such as press machine. However a study on the phase error of RVDT that affects precision is not enough. This paper analyzes RVDT phase error and obtains compensation curves with serial or parallel resistance through simulation. First, error compensation procedure that analyses errors due to the unbalance of reference inductances of each pole and uses parallel resistance as a compensation is proposed. Second, error compensation procedure due to the amplitude unbalance of the sensor driving currents is examined by serial compensation resistance. Experimentally, we got stable RVDT with phase error under $1^{\circ}$ by the proposed method.

• Journal of KSNVE
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• v.9 no.3
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• pp.570-576
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• 1999

This paper presents numerical and experimental results of modal parameter identification in a generator stator frame for 500 MW fossil power plants. A commercial finite element analysis S/W was employed for modal analysis. The generator is excited by alternating electromagnetic forces, mainly of 120 Hz in 60 Hz machines, due to magnetic field and electric current in windings. It is necessary to verify that the stator frame has adequate frequency margin from the excitation frequency to avoid possible resonance when operating. Thus, frequency margin required for the stator frame is established using the numerical and experimental results. The results show that the stator frame meets the frequency-margin requirements. Also, results of modal analysis for design modification in order to reduce weights of the stator frame without deteriorating vibration characteristics are presented.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.752-753
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• 2008

The analytical expressions for magnetic field distributions considering slotting effects, cogging torque and back-emf considering skew effects are established. On the basis of magnetic field solutions, electrical parameters such as back-emf constant and winding inductance are obtained. The predicted results are validated extensively by non-linear finite element (FE) analyses. In particular, test results such as back-emf, cogging torque, inductance and resistance measurements are given to confirm the analyses. Finally, generating performances are investigated by applying estimated parameters to equivalent circuit (EC) of the permanent magnet generator (PMG) and validated extensively by FE calculations and measurements.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.836-837
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• 2008

현재 화석에너지 고갈에 따른 다양한 신재생에너지의 활용에 대한 연구가 활발히 진행되고 있다. 본 논문은 영구자석을 사용한 수력용 영구자석 다극형 동기발전기의 기동토크 저감을 위한 최적설계 방안에 대해 연구를 수행하였다. 먼저 FEA 해석기법을 이용한 수력용 영구자석 다극형 동기발전기의 설계 및 발전기 기동토크에 가장 큰 영향을 주는 코깅토크 저감 방안에 대해 연구하였다. 코깅토크 저감을 위해 고정자 skew비에 따른 코깅토크의 변화를 FEA해석기법을 통해 알아보았으며, 실제 고정자에 skew를 적용하였을 때, 코깅토크의 최소화에 가장 적합함을 알 수 있었다. 또한 실제 설계된 영구자석 다극형 동발전기의 출력 및 코깅토크 측정 결과와 FEA해석결과를 비교 및 분석하여 FEA해석방법의 타당성을 입증하였다.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.812-813
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• 2015

본 논문은 권선계자형 동기전동기(WFSM : Wound Field Synchronous Motor)의 토크리플을 저감시키기 위한 설계 기법을 제시하고자 한다. 돌극형 회전자의 극판(Pole Plate)을 좌우 비대칭으로 축방향 길이을 반으로 나누어 2가지 모델에 대한 합성 파형을 분석한다. 기존의 연구된 스큐 기법과 비슷하게 합성 파형에 의해서 토크리플이 저감된다. 그리고 비대칭 기법과 스큐 기법을 비교하는 형식으로 운전 영역 내에서의 몇 가지 운전 점에서 특성을 비교 분석하였다.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.916-917
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• 2015

This paper deals with electromagneitc characteristics analysis of high-speed brushless DC motor. First, under same rated and restricted conditions, four models which have different slot combinations each other are designed using 2-d finite element (FE) analyses. Designed models are analyzed and compared in terms of core loss, copper loss, eddy-current loss, etc. On the basis of analysis results, it is found that the motor with a 2-pole PM rotor and a 6-slot stator has most outstanding performances in electromagnetic aspects.

• Proceedings of the KIPE Conference
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• 2003.07b
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• pp.824-827
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• 2003

Recently, Development of Rare Earth Permanent magnet with the high remanence, high coercivity allow the design of brushless motors with very high efficiency over a wide speed range. Cogging torque is produced in a permanent magnet by magnetic attraction between the rotor mounted permanent magnet and the stator teeth. It is an undesired effect that contributes to the machines output ripple, vibration, and noise. This cogging torque can be reduced by variation of magnet arc length, airgap length, magnet thickness, shifting the magnetic pole and varying the radial shoe depth and etc. In this paper, Some airgap length and magnet arc that reduce cogging torque are found by FEM(Finite element method). The SPM type of high-capacity BLDC motor is optimized as a sample model.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.758-762
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• 1998

Many harmonics components are contained within the stator currents of the high-speed synchronous reluctance motor, SynRM, with salient pole rotor. They cause the power factor of SynRM to get worse. In this paper, the mathematical model of SynRM is investigated, and SV_PWM control method is applied to reduce harmonics components in the stator current. Simulation results show the fast response of speed and the reduction of harmonics components at steady state.

• Proceedings of the KIEE Conference
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• 2008.10c
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• pp.93-95
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• 2008

Nowadays more attention is paid to the developing high efficiency electrical machines for energy saving and protection of natural resources. In general, the electromagnetic losses appearing in electrical machines are widely classified into copper loss, core loss and rotor loss. Particularly, in permanent magnet (PM) machines, core loss forms a larger portion of the total losses than in another machine. So, satisfactory prediction of core loss at the design or analysis stage of PM machines is essential to active high efficiency and high performance. This paper deals with analysis of magnetic field distribution due to geometry of stator core for magnetic core loss calculation of multi-pole PM synchronous machine.