• Proceedings of the KIEE Conference
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• 1989.11a
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• pp.37-40
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• 1989

When we analyze the magnetostatic problem by the FEM, it is a traditional method to use the magnetic vector potential as an unknown variable.(abbreviated to A Method) Therefore, we should differentiate this magnetic vector potential to get the magnetic flux density. In this procedure of differentiation, the accuracy of the calculation is reduced. In order to overcome this problem, this paper uses the magnetic flux density as an unknown variable.(abbreviated to B Method) The validity of this new method (B Method) to use the magnetic flux density directly as an unknown variable, is ensured as the result of the application example researches.

• Journal of international Conference on Electrical Machines and Systems
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• v.1 no.1
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• pp.23-31
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• 2012

Variable-flux permanent-magnet machines (VFPM) are of great interest and many different machine topologies have been documented. This paper categorizes VFPM machine topologies with regard to the method of flux variation and further, in the case of hybrid excited machines with field coils, with regard to the location of the excitation sources. The different VFPM machines are reviewed and compared in terms of their torque density, complexity and their ability to vary the flux.

• The Transactions of the Korean Institute of Power Electronics
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• v.11 no.5
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• pp.417-425
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• 2006

This paper presents a new speed sensorless vector control scheme of Spindle Induction Motors(SIM) which can be successfully applied to at any speed including even zero speed. The proposed sensorless vector control of SIM uses rotor flux estimator with a variable bandwidth. This approach is based on the Closed-Loop Rotor Flux Observer(CLRFO) which includes a variable bandwidth of the PI controller. For low speed operation, the bandwidth of CLRFO has a variable bandwidth structure according to the estimated rotor velocity. The experimental results show the satisfactory operation of the proposed sensorless algorithm.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.890-891
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• 2015

본 논문에서는 속도 제어를 위한 가변자속 메모리 모터(Variable Flux Memory Motor)의 특성과 감자전류 산정에 대하여 다루었다. 서론에서는 VFMM에 대한 특징 및 설계를 위한 분석 방안을 제시하였으며, 메모리모터의 동작 원리와, 정밀한 해석 방법은 본론을 통하여 자세히 다루었다. 감자전류는 프라이자흐 모델을 이용하여 초기 자석의 자화량을 비선형 적으로 구한 후 인가된 d축 전류에 따른 변화된 자화량 및 기전력 값들을 반복적인 연산을 통하여 신뢰성 있는 감자전류를 산정하였다.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.50 no.7
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• pp.307-314
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• 2001

A moving coil linear oscillatory actuator is consisted of the NdFeB permanent magnets with high specific energy as the stator, a coil-wrapped nonmagnetic hollow rectangular structure and an iron core as a pathway for magnetic flux. The variation of mover position and the consequent changes of coil flux path affect the coil inductance, because coil flux leaks at the open region of LOA stator. The interaction between permanent magnet and armature field is to shift the airgap flux density variation due to the magnet alone by a certain amount. The unbalanced reciprocation force due to armature reaction field decreases the advantage of moving coil LOA, such as a high degree of linearity and controllability in the force ad motion control. This paper firstly describes the coil inductance, the deviation of flux density, and the unbalanced reciprocation force, which are derived form the permeance model of LOA. Secondly, the analytical method are verified using the 2D finite element method and tests. Finally, the dynamic simulation algorithm taking the armature reaction effect and variable inductance into account, is proposed and confirmed through the experiment.

• Journal of computational fluids engineering
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• v.5 no.1
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• pp.43-59
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• 2000

Characteristic boundary conditions are discussed in conjunction with a flux-difference splitting formulation as modified from Roe's linearization. Details of how one can implement the characteristic boundary conditions which are made compatible with the interior point formulation are described for different types of boundaries including subsonic outflow and adiabatic wall. The validity of boundary conditions are demonstrated through computation of transonic airfoil, supersonic ogive-cylinder, hypersonic cylinder, and S-duct internal flows. The computed wall pressure distributions are compared with published experimental and computed data. Objectives of this paper are thus to give insight of formulation procedure of a flux-difference splitting method and to pave ways for other users to adopt present boundary procedure on their numerical methods.

• Proceedings of the KIEE Conference
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• summer
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• pp.905-907
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• 2004

This paper deals with the PM performance evaluations in a variable flux memory motor (VFMM) using a coupled finite element method (FEM) and Preisach modeling, which is presented to analyze the magnetic characteristics of permanent magnets. The focus of this paper is the operation characteristics evaluation relative to magnetizing direction and quantity of permanent magnets on re-, demagnetization condition in a variable flux memory motor(VFMM)

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1003-1004
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• 2007

This paper deals with the PM performance evaluations in a variable flux memory motor (VFMM) using a coupled finite element method (FEM) and Preisach modeling, which is presented to analyze the magnetic characteristics of permanent magnets. The focus of this paper is the operation characteristics evaluation relative to magnetizing direction and quantity of permanent magnets on redemagnetization condition in a variable flux memory motor(VFMM).

• Proceedings of the KIEE Conference
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• 2001.04a
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• pp.156-159
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• 2001

This Paper analysis variable characteristics of inductance profiles and basic magnetic fields for Switched Reluctance Motors(SRM). The varying Inductance and flux linkage on operating control condition are very important for developing control algorithm and SRM accurate drive system. Therefore, we have analytical model for varying inductance and flux linkage with simulation and experimental mothed, and to find an analytical expression for the SRM coenergy. There are shown some good results that comparison of simulated and analytical inductance, flux linkage and current waves.

• Proceedings of the KIEE Conference
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• 2000.11b
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• pp.336-338
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• 2000

Recently many studies have been performed for variable speed control of induction motor. Direct Torque Control(DTC) is emerging technique for variable speed control of PWM inverter driven induction motor. DTC allows the direct control of stator flux and instantaneous torque through simple algorithm. In this paper ASIC design technique using VHDL is applied to DTC based speed control of induction motor. ASIC for DTC based speed control is designed through the description of coordinate transformation, speed controller stator flux and torque estimator, stator flux and torque controller, stator flux position detector. FSM(Finite State Machine) and inverter voltage switching vector. Finally the above system has been implemented on the FPGA (XC4052XL-PG411). Simulation and experiment has been performed to verify the performance of the designed ASTC.