Abstract：The exact analytical method is applied to compute air-gap main magnetic field distribution, cogging torque and electromotive force (EMF) in surface-mounted permanent-magnet (PM) motors. The solution regions are divided into air-gap domain, permanent magnet domain and slot domains. The Laplace’s or Poisson’s equations of the sub-domains are solved by the exact analytical method and the solutions are obtained using boundary and interface conditions. The actual depth of slot and distance between slots are taken into account in the computation. Air-gap magnetic field distributions, cogging torque and EMF waveform computed with the proposed analytical method are respectively compared with those issued from two-dimensional finite-element analysis and experimental waveforms, the comparison results are consistent and show the correctness and effectiveness of the proposed analytical method.
[1] Zhu Z Q, Howe D, Bolte E. Instantaneous magnetic field distribution in brushless permanent magnet DC motors, part I: open-circuit field[J]. IEEE Transactions on Magnetics, 1993, 29(1): 124-135. [2] Zhu Z Q, Howe D. Instantaneous magnetic field distribution in brushless magnet DC motors, part III effect of stator slotting[J]. IEEE Transactions on Magnetics, 1993, 29(1): 143-151. [3] Damir Zarko, Drago Ban, Thomas A Lipo. Analytical calculation of magnetic field distribution in the slotted air gap of a surface permanent-magnet motor using complex relative air-gap permeance[J]. IEEE Transactions on Magnetics, 2006, 42(7): 1828-1837. [4] Zhilichev Y. Analysis of permanent magnet machines using crossing macro-elements[J]. IEEE Transactions on Magnetics, 2000, 36(5): 3122-3124. [5] 丁晔, 章跃进. 表面磁钢永磁无刷电机空载气隙磁场半解析法研究[J]. 电机与控制应用, 2007(3): 7-10. Ding Ye, Zhang Yuejin. Semi-analytical method research for non-load air gap field of surface alnico permanent magnet brushless motor[J]. Electric Machine and Control Application, 2007(3): 7-10. [6] 郑成勇, 章跃进, 薛波, 等. 表贴式分数槽电机永磁气隙磁场矢量位半解析法[J]. 微特电机, 2010(4): 24-26. Zheng Chengyong, Zhang Yuejin, Xue Bo, et al. Semi-analytical approach with vector magnetic potential for permanet-magnet air-gap field of surface mounted stator slot[J]. Small and Special Electrical Machines, 2010(4): 24-26. [7] 李春江, 章跃进, 卢铁斌, 等. 解析数值结合法在直驱轮毂式永磁无刷电机气隙磁场分析中的应用[J]. 微电机, 2010, 43(12): 21-28. Li Chunjiang, Zhang Yuejin, Lu Tiebin, et al. Application of analytical-numerical method to air-gap magnetic field of direct drive wheel-hub permanent magnet brushless motors[J]. Micromotors, 2010, 43(12): 21-28. [8] Thierry Lubin, Smail Mezani, Abderrezak Rezzoug. Exact analytical method for magnetic field computation in the air gap of cylindrical electrical machines considering slotting effects[J]. IEEE Transactions on Magnetics, 2010, 46(4): 1092-1099. [9] 胡之光. 电机电磁场的分析与计算[M]. 北京: 机械工业出版社, 1986.
2012, Vol. 27 
