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Heesung Yoon,Yanli Zhang,ChangSeop Koh IEEE 2013 IEEE transactions on magnetics Vol.49 No.5
<P>This paper presents a convergence stabilization method of E&S vector hysteresis model when it is combined with nonlinear finite element analysis (FEA). In order to ensure the stable convergence, an additional nonlinear iterative procedure with a relaxation method is incorporated with the conventional nonlinear FEA, and adaptive determination of relaxation factor during the nonlinear iteration is suggested. The effectiveness of the suggested method is verified through a comparison of the numerical results from the suggested and conventional methods.</P>
Heesung Yoon,Minho Song,Inhyun Kim,Pan Seok Shin,Chang Seop Koh IEEE 2012 IEEE transactions on magnetics Vol.48 No.2
<P>This paper presents an improved dynamic E&S vector hysteresis model to increase modeling accuracy under non-elliptic <I>B</I>-waveforms and describes its implementation to the finite element method (FEM). Since the dynamic E&S model is expressed via magnetic reluctivity and hysteresis coefficients modeling the vector hysteresis property of electrical steel sheet, its modeling accuracy strongly depends on the method of determination of the coefficients. The proposed model increases the modeling accuracy by improving the coefficient calculation algorithm especially under non-elliptic distorted magnetic flux density conditions. The proposed model is incorporated with FEM and applied to iron loss analysis of a three-phase induction motor.</P>
Heesung Yoon,Inhyun Kim,Pan Seok Shin,Chang Seop Koh IEEE 2011 IEEE transactions on magnetics Vol.47 No.5
<P>This paper presents a generalized Chua-type vector hysteresis model, and a precise magnetic field analysis method is developed by combining the proposed model with the finite element method. The proposed model takes account of all the significant harmonic components of the measured <I>H</I>-waveforms. The validity of the proposed model is investigated through an application to a three-phase transformer model and comparison to experimental measurement.</P>
Yoon, Heesung,Jang, Seok-Myeong,Koh, Chang Seop Journal of International Conference on Electrical 2013 Journal of international Conference on Electrical Vol.2 No.2
This paper presents the iron loss prediction of rotating electric machines taking account of the vector hysteretic properties of electrical steel sheet. The E&S vector hysteresis model is adopted to describe the vector hysteretic properties of a non-oriented electrical steel sheet, and incorporated into finite element analysis (FEA) for magnetic field analysis and iron loss prediction. A permanent magnet synchronous generator is taken as a numerical model, and the analyzed magnetic field distribution and predicted iron loss by using the proposed method is compared with those from a conventional method which employs an empirical iron loss formula with FEA based on a non-linear B-H curve. Through the comparison the effectiveness of the presented method for the iron loss prediction of the rotating machine is verified.
전기강판의 벡터 자기특성을 고려한 전기기기의 손실특성 해석
윤희성(Heesung Yoon),고창섭(Chang Seop Koh) 대한전기학회 2012 전기학회논문지 Vol.61 No.12
This paper presents vector magnetic properties of an electrical steel sheet (ESS) employed for electric machine and iron loss analysis considering the vector magnetic properties of the ESS. The vector magnetic properties of the ESS are measured by using a two-dimensional single sheet tester and modeled by an E&S vector hysteresis model to be applied to finite element method. The finite element analysis considering the vector magnetic properties is applied to iron loss analysis of a three-phase induction motor model, and the influences of the vector magnetic properties on the iron loss distribution are verified by comparing with numerical results from a typical B-H curve model.
열전냉각시스템 냉각영역의 성능개선을 위한 압전구동기 적용에 관한 연구
윤희성(Heesung Yoon),최제세(Jese Choi),오율권(Yoolkwon Oh) 한국자동차공학회 2009 한국자동차공학회 학술대회 및 전시회 Vol.2009 No.11
This study investigated on performance improvement of cooling region in thermoelectric cooling system when piezoelectric actuator was applied. In this study, piezoelectric actuator was used for generating vibration in cooling region of thermoelectric cooling system. When vibration was generated by the piezoelectric actuator, temperature distribution was measured using thermocouples for investigating cooling characteristics in cooling region of thermoelectric cooling system. Also, He-Ne laser and CCD camera were used for flow visualization in cooling region. The experimental set-up for temperature measurement and the flow visualization in cooling region consisted of thermoelectric cooling system, piezoelectric actuator, thermocouples, data acquisition units, He-Ne laser, CCD camera, image grabber and PC. As a result, it was certified that vibration of piezoelectric actuator generated forced convection, and the cooling efficiency in the cooling region was improved when piezoelectric actuator was applied.
시간차분 유한요소법을 이용한 대용량 삼상 변압기의 정상상태 해석에 관한 연구
윤희성(Heesung Yoon),서민규(Min Kyu Seo),고창섭(Chang Seop Koh) 대한전기학회 2012 전기학회논문지 Vol.61 No.8
This paper presents the fast steady state analysis using time-stepping finite element method for a high power three-phase transformer. The high power transformer spends huge computational cost of the time-stepping finite element method. It is because that the high power transformer requires a lot of time to reach steady state by its large inductance component. In order to reduce computational cost, in this paper, the adaptive time-step control algorithm combined with the embedded 2nd 4th singly diagonally implicit Runge-Kutta method and the analysis strategy using variation of the winding resistance are studied, and their numerical results are compared with those from the typical time-stepping finite element method.