Is Higher Resistivity of Magnet Beneficial to Reduce Rotor Eddy Current Loss in High-Speed Permanent Magnets AC Machines?
Shen Jianxin1,2, Han Ting1,2, Yao Lei1,2, Wang Yunchong1,2
1. College of Electrical Engineering Zhejiang University Hangzhou 310027 China; 2. Zhejiang Provincial Key Laboratory of Electrical Machine Systems Hangzhou 310027 China
Abstract When permanent magnets (PM) are exposed to harmonic fields, eddy current exists if the magnets are electrically conductive, causing power loss. Increasing the magnet resistivity is a direct way to reduce the eddy current in the magnets. However, in high-speed PM AC machines, eddy current occurs not only in the magnets, but also in the metal retaining sleeve and the copper shielding layer of the rotor. Under such a circumstance, is the technique of increasing the magnet resistivity still workable? This will be answered in this article, through a comparative finite element analysis.
Fund:This work was supported by the Natural Science Foundation of China under the grants of 51837010 and 51690182.
Corresponding Authors:
Wang Yunchong born in 1987, associate professor. His main research interests include design and control of high speed machines, PM machines and SynRM.E-mail: wangycee@zju.edu.cn
About author:: Shen Jianxin born in 1969, professor. His main research interests include design, control and applications of PM machines, SynRM, high speed machines, and high efficiency motor drives.E-mail: J_X_Shen@zju.edu.cn
Shen Jianxin,Han Ting,Yao Lei等. Is Higher Resistivity of Magnet Beneficial to Reduce Rotor Eddy Current Loss in High-Speed Permanent Magnets AC Machines?[J]. Transactions of China Electrotechnical Society, 2020, 35(9): 2074-2078.
[1] Sun Quangui, Deng Zhiquan, Zhang Zhongming.Analytical calculation of rotor eddy current losses in high speed permanent magnet machines accounting for influence of slot opening[J]. Transactions of China Electrotechnical Society, 2018, 33(9): 1994-2004. [2] Wang Tianyu, Wen Fuqiang, Zhang Fengge, et al.Analysis of multi-field coupling strength for MW high-speed permanent magnet machine[J]. Transa- ctions of China Electrotechnical Society, 2018, 33(19): 4058-4516. [3] Zeng Yingyu,Jiang Xiaohua.A similarity method based on spectrum compression for calculating eddy current loss in magnets of PM machines fed by PWM voltage[J]. Transactions of China Electrotechnical Society, 2018, 33(2): 943-954. [4] Katsumi Y, Yu F.Effect of eddy-current loss reduction by magnet segmentation in synchronous motors with concentrated windings[C]//2009 Inter- national Conference on Electrical Machines and Systems, Tokyo, 2009: 1-6. [5] Chins C, Melania M J, Daniel P, et al.High electrical resistivity Sm (Co,Fe,Cu,Zr)z/Sm2S3 permanent magnets with layered structure for advanced motors[J]. IEEE Transactions on Magnetics, 2012, 48(11): 3166-3169. [6] Matahiro K, Yuichi S, Yuji E. Enomoto, et al. High electrical resistance hot-pressed NdFeB magnet for low loss motors[J]. Applied Physics Letters, 2007, 91(10): 102503-102503-3. [7] Han Ting, Wang Yunchong, Qin Xuefei, et al.Investi- gation of various rotor retaining sleeve structures in high-speed PM brushless motors[C]//2018 Inter- national Conference on Electrical Machines and Systems, Jeju, 2018: 1-6. [8] Masayuki M, Kenichi A, Takao S, et al.Position sensorless starting of super high-speed PM generator for micro gas turbines[J]. IEEE Transactions on Industrial Electronics, 2006, 53(2): 415-420. [9] Chen Jiaxin, Guo Youguang, Zhu Jianguo.Deve- lopment of a high-speed permanent-magnet brushless DC motor for driving embroidery machines[J]. IEEE Transactions on Magnetics, 2007, 43(11): 4004-4009. [10] Jang S M, Cho H W, Choi S K.Design and analysis of a high-speed brushless DC motor for centrifugal compressor[J]. IEEE Transactions on Magnetics, 2007, 43(6): 2573-2575. [11] Shen J X, Hao H, Yuan C.FEA study on circum- ferential grooves on rotor retaining sleeve of high- speed PM brushless motors[J]. IEEE Transactions on Magnetics, 2012, 32(36): 53-60. [12] Zhou Fengzheng, Shen Jianxin, Fei Weizhong.Study of retaining sleeve and conductive shield and their influence on rotor loss in high-speed PM BLDC motors[J]. IEEE Transactions on Magnetics, 2006, 42(10): 3398-3400.
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