Abstract：A similarity method with frequency domain compression is proposed for calculating the eddy current loss in permanent magnets (PM) of machines fed by pulse width modulation (PWM) voltage. The method transforms the high frequency (HF) eddy current problem to a lower frequency one, which reduces the time steps and computation time for the finite element analysis (FEA). Beyond previous similarity methods, the magnetic saturation of iron core is considered, and the fundamental voltage, frequency, and rotation speed are kept unchanged. Taken equal penetration depth for HF in eddy current regions as the precondition, the similarities in machine current, magnetic field and eddy current loss are analyzed by analytical method. The proposed method is verified by time stepping FEA of a surface-mounted PM machine with magnetic saturation in its stator teeth. The results suggest that the discrepancy is within 6.6% for the HF components in stator current, and the discrepancy in eddy current loss is -4.75% when the similarity ratio equals 4, while the computation time is 1/5 of the traditional FEA. By measuring the impedance variation in coils after placing metal blocks inside and the temperature of PM in a PM machine, the similarity correlations and the eddy current loss calculation are verified.
曾颖宇, 蒋晓华. 基于相似原理的脉宽调制电压激励下电机永磁体涡流损耗频域压缩计算方法[J]. 电工技术学报, 2018, 33(4): 943-954.
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. Transactions of China Electrotechnical Society, 2018, 33(4): 943-954.
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2018, Vol. 33 
