Abstract：Cogging torque is one of the important issues for permanent magnet (PM) wind power generator. To reduce the cogging torque, the expression of the cogging torque is studied based on the Fourier analysis. In this paper, a concept of repeat unit is proposed. It is found that the cogging torque is multiple of the cogging torque generated of a repeating unit, and a certain harmonic of cogging torque could be eliminated by relative shifting of repeat units with proper shifting angles. Based on the repeat unit, a method of PM shifting to reduce cogging torque of permanent magnet machine is presented. The new method to obtain the PM shifting angles is achieved. At last the method is verified by finite element method. The results show that the method to obtain the PM shifting angles is simple. With this method the cogging torque can be greatly reduced.
刘婷, 欧阳红林, 黄守道. 基于重复单元削弱永磁风力发电机齿槽转矩[J]. 电工技术学报, 2011, 26(12): 43-48.
Liu Ting, Ouyang Honglin, Huang Shoudao. Reducing Cogging Torque in Permanent Magnet Wind Power Generators Based on Repeat Unit. Transactions of China Electrotechnical Society, 2011, 26(12): 43-48.
[1] Zhu Z Q, Howe D. Influence of design parameters on cogging torque in permanent magnet machines[J]. IEEE Transactions on Energy Conversion, 2000, 15(4): 407-412. [2] Yang Y B, Wang X H, Zhang R, et al. The optimization of pole arc coefficient to reduce cogging torque in surface-mounted permanent magnet motors[J]. IEEE Transactions on Magnetics, 2006, 42(4): 1135-1138. [3] Kim K C, Koo D H, Hong J P, et al. A study on the characteristics due to pole-arc to pole-pitch ratio and saliency to improve torque performance of IPMSM [J]. IEEE Transactions on Magnetics, 2007, 43(6): 2516-2518. [4] Hwang S M, Eom J B, Jung Y H, et al. Various design techniques to reduce cogging torque by controlling energy variation in permanent magnet motors[J]. IEEE Transactions on Magnetics, 2001, 37(4): 2806-2809. [5] Lateb R, Takorabet N, Meibody Tabar F. Effect of magnet segmentation on the cogging torque in surface-mounted permanent-magnet motors[J]. IEEE Transactions on Magnetics, 2006, 42(3): 442-445. [6] Zhu Z Q, Ruangsinchaiwanich S, Chen Y, et al. Evaluation of superposition technique for calculating cogging torque in permanent-magnet brushless machines[J]. IEEE Transactions on Magnetics, 2006, 42(3): 1597-1603. [7] Lukaniszyn M, Jagiela M, Wrobel R. Optimization of permanent magnet shape for minimum cogging torque using a genetic algorithm[J]. IEEE Transactions on Magnetics, 2004, 40(2): 1228-1231. [8] Islam R, Husain I, Fardoun A, et al. Permanent- magnet synchronous motor magnet designs with skewing for torque ripple and cogging torque reduction[J]. IEEE Transactions on Industry Applications, 2009, 45(1): 152-160. [9] Kim T H, Won S H, Bong K, et al. Reduction of cogging torque in flux-reversal machine by rotor teeth pairing [J]. IEEE Transactions on Magnetics, 2005, 41(10): 3964-3966. [10] Zhu L, Jiang S Z, Zhu Z Q, et al. Analytical methods for minimizing cogging torque in permanent-magnet machines[J]. IEEE Transactions on Magnetics, 2009, 45(4): 2023-2031. [11] Dutta R, Sayeef S, Rahman M F. Cogging torque analysis of a segmented interior permanent magnet machine[C]. International Conf on Electric Machines & Drives, Sydney, 2007, 1: 781-786. [12] Touzhu L, Slemon G. Reduction of cogging torque in permanent magnet motors[J]. IEEE Transactions on Magnetics, 1988, 24(6): 2901-2903. [13] Ishikawa T, Slemon G R. A method of reducing ripple torque in permanent magnet motors without skewing[J]. IEEE Transactions on Magnetics, 1993, 29 (2): 2028-2031. [14] Bianchi N, Bolognani S. Design techniques for reducing the cogging torque in surface-mounted PM motors[J]. IEEE Transactions on Industry Applica- tions, 2002, 38(5): 1259-1265. [15] 杨玉波, 王秀和, 张鑫, 等. 磁极偏移削弱永磁电机齿槽转矩方法[J]. 中国电机工程学报, 2006, 21(10): 22-25. Yang Yubo, Wang Xiuhe, Zhang Xin, et al. Study of magnet shifting for reduction of cogging torque in permanent magnet motors[J]. Proceedings of the CSEE, 2006, 21(10): 22-25. [16] Dosiek L, Pillay P. Cogging torque reduction in permanent magnet machines[J]. IEEE Transactions on Industry Applications, 2007, 43(6): 1565-1571. [17] Bianchi N, Bolognani S, Cappello A D F. Reduction of cogging force in PM linear motors by pole- shifting[J]. IEE Proceedings on Electric Power Applications, 2005, 152(3): 703-709. [18] Breton C, Bartolome J, Benito J A, et al. Influence of machine symmetry on reduction of cogging torque in permanent magnet brushless motors[J]. IEEE Transactions on Magnetics, 2000, 36(5): 3819-3823. [19] Hanselman D. Brushless permanent-magnet motor design[M]. New York: Mc Graw-Hill, 1994. [20] 王秀和. 永磁电机[M]. 北京: 中国电力出版社, 2007.
2011, Vol. 26 
