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해석적 방법을 이용한 표면부착형 영구자석 기기의 회전자 와전류 손실해석
최장영(Jang-Young Choi),최지환(Ji-Hwan Choi),장석명(Seok-Myeong Jang),조한욱(Han-Wook Cho),이성호(Sung-Ho Lee) 대한전기학회 2012 전기학회논문지 Vol.61 No.8
This paper analyzes eddy-current loss induced in magnets of surface-mounted permanent magnet (SPM) machines by using an analytical method such as a space harmonic method. First, on the basis of a two-dimensional (2D) polar coordinate system and a magnetic vector potential, the analytical solutions for the flux density produced by armature winding current are obtained. By using derived field solutions, the analytical solutions for eddy current density distribution are also obtained. Finally, analytical solutions for eddy current loss induced in rotor magnets are derived by using equivalent electrical resistance calculated from magnet volume and analytical solutions for eddy-current density distribution. In particular, the influence of time harmonics in armature current on the eddy current loss is fully investigated and discussed. All analytical results are validated extensively by finite element analysis (FEA).
Ring-Wound형 슬롯리스 고정자를 갖는 양측식 축 자속 영구자석 전동기의 전자기적 특성해석
최장영(Jang-Young Choi),박유섭(Yu-Seop Park),장석명(Seok-Myeong Jang) 대한전기학회 2010 대한전기학회 학술대회 논문집 Vol.2010 No.4
This paper deals with electromagnetic analysis of double-sided axial flux permanent magnet (AFPM) motor with ring-wound type slotless stator. On the basis of magnetic vector potential and polar-coordinate system, the magnetic field solutions due to PM rotor are obtained. In particular, 3-D problem, that is, the reduction of magnetic fields near outer and inner radius of the PM is solved by introducing a special function for radial position. And then, analytical solutions for torque and back-emf are also derived. The predictions are shown in good agreement with those obtained from 3-D finite element (FE) analyses. Therefore, it can be concluded that analytical solutions derived in this paper will be useful for initial design stage of the AFPM motor.
전기자동차 압축기용 표면부착형 영구자석 전동기의 극/슬롯수 조합에 따른 특성해석 및 설계
최장영(Jang-Young Choi),박형일(Hyung-Il Park),장석명(Seok-Myeong Jang),이성호(Sung-Ho Lee) 대한전기학회 2011 전기학회논문지 Vol.60 No.10
This paper deals with design and analysis of surface-mounted PM (SPM) motor for compressor of air-conditioning system for electric vehicle applications according to slot/pole combination. First, required torque-speed curve characteristics are determined from operating conditions of the compressor. Restricted conditions such as motor size limit and current density are also determined. And then, under same rated and restricted conditions, twelve models which have different slot/pole combinations each other are designed for various pole arc/pitch ratio using simple equations and 2-d finite element (FE) analyses. Designed models are analyzed and compared in terms of back-emf THD, cogging torque, torque ripple, power losses, efficiency, etc. On the basis of analysis results, it is found that the motor with a 6-pole PM rotor and a 27-slot stator has most outstanding performances in electromagnetic aspects. Finally, through the mechanical modal analysis and demagnetization analysis, it is concluded that the determined motor is most suitable for the compressor of air-conditioning system for electric vehicles
이중여자 유도발전기에 의한 가변속 풍력 발전시스템의 동특성 해석
崔璋英(Jang-Young Choi),張錫明(Seok-Myeong Jang) 대한전기학회 2006 전기학회논문지 B Vol.55 No.6
This paper deals with the dynamic analysis of variable speed wind power systems with doubly-fed induction generators (DFIG). First, the mathematical modeling of wind farm which consists of turbine rotor, DFIG, rotor side and grid side converter and control systems is presented. In particular, the equation for dynamic modeling of the DFIG and the AC/DC/AC converter is expressed as dq reference frame. And then, on the basis of mathematical modeling for each component of wind farm, dynamic simulation algorithms for speed and pitch angle control of wind turbine and generated active and reactive power control of the DFIG and the AC/DC/AC converter are established. Finally, Using the MATLAB/SIMULINK, this paper presents dynamic simulation model for 6㎿ wind power generation systems with the DFIG considering distribution systems and performs the dynamic analysis of wind power systems in steady state. Moreover, this paper also presents the dynamic performance for the case when the voltage sag in grid source and phase fault in bus are occurred.
공간고조파법을 이용한 축 자속 영구자석 회전기기의 準-3D 특성 해석
최장영(Jang-Young Choi) 대한전기학회 2011 전기학회논문지 Vol.60 No.5
This paper deals with characteristic analysis of axial flux permanent magnet (AFPM) machines with axially magnetized PM rotor using quasi-3-D analysis modeling. On the basis of magnetic vector potential and a two-dimensional (2-D) polar-coordinate system, the magnetic field solutions due to various PM rotors are obtained. In particular, 3-D problem, that is, the reduction of magnetic fields near outer and inner radius of the PM is solved by introducing a special function for radial position. And then, the analytical solutions for back-emf and torque are also derived from magnetic field solutions. The predictions are shown in good agreement with those obtained from 3-D finite element analyses (FEA). Finally, it can be judged that analytical solutions for electromagnetic quantities presented in this paper are very useful for the AFPM machines in terms of following items : initial design, sensitivity analysis with design parameters, and estimation of control parameters.
비전도성 폐기물 용융처리를 위한 혼합형 플라즈마토치 시스템 특성 연구
문영표(Young-Pyo Moon),최장영(Jang-Young Choi) 대한전기학회 2016 전기학회논문지 Vol.65 No.1
The preliminary test for the dual mode plasma torch system was carried out to explore the operation properties in advance. The dual mode plasma torch system that is able to operate in transferred, non-transferred, or dual mode is very adequate for melting the mixed wastes including nonconductive materials such as concrete, asbestos, etc. since it exploits both the high efficiency of heat transfer to the melt in transferred mode and stable operation in non-transferred mode. Also, system operation including restarting is reliable and very easy. A stationary melter with a refractory structure was designed and manufactured considering the melting behavior of slags to minimize the refractory erosion. The power supply for the dual mode plasma torch system built with high power insulated gate bipolar transistor (IGBT) modules has functions for both current control and voltage control and is sufficient to suppress the harmonics during the operation of the plasma torch. The power supply provides two different voltages for transferred operation and non-transferred. It is confirmed that the operation voltage in transferred is always higher than non-transferred. The dual mode plasma torch system was successfully developed and is under operation for a melting experiment to optimize operation data.