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퍼미언스 방법을 이용한 스위치드 릴럭턴스 전동기의 인덕턴스 산정
이치우(Cheewoo Lee) 대한전기학회 2012 전기학회논문지 Vol.61 No.12
Torque is proportional to the rate of change of inductance in a switched reluctance motor (SRM), and hence, phase inductance is an important parameter in determining the behavior of an SRM. Therefore, the accurate prediction of inductance with respect to rotor position makes a significant contribution to designing an SRM and its analytical approach is not straightforward due to nonlinear flux distribution. Although several different approaches using a finite element analysis (FEA) or curve-fitting tool have been employed to compute phase inductance [2-5], they are not suitable for a simple design procedure because the FEA necessitates a large amount of time in both modeling and solving with complexity for every motor design, and the curve-fitting requires the data of flux linkage from either an experimental test or an FEA simulation. In this paper, phase inductance is predicted by means of a permeance method, and the proposed approach is analytically verified in terms of the accuracy of estimated inductance compared to inductance obtained by FEA.
치수적 결함에 따른 PMSM의 법선방향 힘의 변화에 관한 연구
이치우(Cheewoo Lee) 대한전기학회 2010 전기학회논문지 Vol.59 No.11
Main reasons for causing vibration in a permanent magnet synchronous motor (PMSM) are torque ripple and radial force harmonics, and hence, both of them are undesirable in high-precision machine tools and accurate motion-control actuators. Recent research on radial force is the prediction of major vibration frequencies and modes in terms of motor design such as different winding types and a fractional slot number per pole in the stator. Also, proper phase current has been investigated for minimizing radial force harmonics. During the previous studies, all the motors are assumed to be ideally built up in terms of mechanical dimensions, but it is impossible due to dimensional variation within or outside tolerance in production. Therefore, in this paper, the effect of several key factors on radial force is examined and compared regarding manufacturing imperfection.
자기등가회로 기법을 사용한 2상 E-core SRM의 해석에 관한 연구
이치우(Cheewoo Lee) 대한전기학회 2010 전기학회논문지 Vol.59 No.11
The modification of magnetic structures for an E-core switched reluctance machine (SRM) comprising two segmented stator cores or a monolithic stator core is presented for ease of assembly, good manufacturability, mechanical robustness, and electromagnetic performance improvement. The E-core stator has four small poles with phase windings and two or four large poles (hereafter referred to as common poles), in between. The common poles are shared by both phases for positive torque generation during the entire operation. The E-core SRMs are compared to a conventional two-phase SRM. The comparison includes cost savings, torque, copper and core losses, and efficiency in order to validate the distinct features of the E-core SRMs. Magnetic equivalent circuit (MEC) technique is employed for proving the benefits of the E-core common-pole structure.
새로운 2상 8/6 SRM의 구조적 특성에 관한 비교 연구
이치우(Cheewoo Lee),황홍식(Hongsik Hwang),오석규(Seok-Gyu Oh) 대한전기학회 2017 전기학회논문지 Vol.66 No.2
This study presents a novel two-phase eight stator poles and six rotor poles (8/6) switched reluctance machine (SRM) that can compensate for the vibration and noise problems of two-phase 6/3 SRM and compare the characteristics of two SRMs. In the case of two-phase 6/3 SRM, the short flux path and the flux direction inside the stator are not reversed, so they have high efficiency characteristics. However, the use of three rotor poles causes problems of vibration and noise because the radial force applied to the rotor poles is not balance. The proposed two-phase 8/6 SRM has advantages of 6/3 SRM such as the fluxreversal-free stator and it can improve vibration and noise by using six rotor poles due to balanced radial force acting on the rotor poles. In order to make a reasonable comparison between two SRMs, the electromagnetic field structure of 8/6 SRM is designed to have equivalent torque characteristic to 6/3 SRM and then the copper loss and core loss are compared and analyzed. Finally, we compare the effieicney of two SRMs using finite element analysis and compare the distribution of radial force acting on the rotor poles based on Maxwell’s stress method
다상 영구자석 동기 전동기의 자기 및 상호 인덕턴스 계산
이치우(Cheewoo Lee) 한국자기학회 2017 韓國磁氣學會誌 Vol.27 No.1
A multi-phase electric machine has gained distinct interest due to its high reliability compared to a three-phase structure, and in this paper, self and mutual inductances in a five-phase permanent magnet synchronous machine (PMSM) are estimated by an analytical method. Recently, most of high-performance operations are implemented by field oriented control and/or direct torque control, and inductance for those controls is one of the key parameters in the voltage equation of phase windings. Winding function theory (WFT) is employed to calculate the inductance of phase windings, and it is verified that the result of the analytical method has a deviation of approximately 3% compared to finite element analysis. Finally, in this paper, the way to obtain direct and quadrature inductance values are introduced from the analytical inductance calculated by WFT.
손실 패턴에 따른 고속 스위치드 릴럭턴스 전동기의 SMC 분말을 이용한 효율 개선
이치우(Cheewoo Lee) 대한전기학회 2017 전기학회논문지 Vol.66 No.2
Soft magnetic composite (SMC) material has recently received a significant attention in the area of high-speed machines because of its unique properties such as good design flexibility and low eddy current loss. However, SMC’s electromagnetic property is poor compared to silicon steel in terms of saturation, relative permeability, and hysteresis loss. This paper presents a technique for utilization of SMC in two strategic designs of a switched reluctance machine (SRM) depending on a loss pattern. To investigate the effect of SMC’s merits and demerits, the stator material is changed from laminated steel to SMC.
스위치드 릴럭턴스 전동기의 회전자 정렬과 비정렬 위치에서의 인덕턴스 예측
이치우(Cheewoo Lee) 대한전기학회 2012 전기학회논문지 Vol.61 No.1
Flux linkage of phase windings or phase inductance is an important parameter in determining the behavior of a switched reluctance motor (SRM) [1-8]. Therefore, the accurate prediction of inductance at aligned and unaligned rotor positions makes a significant contribution to the design of an SRM and its analytical approach is not straightforward due to nonlinear flux distribution. Although several different approaches using a finite element analysis (FEA) or curve-fitting tool have been employed to compute phase inductance [2-5], they are not suitable for a simple design procedure because the FEA necessitates a large amount of time in both modeling and solving with complexity for every motor design, and the curve-fitting requires the data of flux linkage from either an experimental test or an FEA simulation. In this paper, phase inductance at aligned and unaligned rotor positions is estimated by means of numerical method and magnetic equivalent circuit as well, and the proposed approach is analytically verif ied in terms of the accuracy of estimated inductance compared to inductance computed by an FEA simulation.