磁通反向永磁电机齿槽转矩分析与抑制

Analysis and Suppression of Cogging Torque in Flux-reversal Permanent Magnet Machines

由于特殊的双凸极结构,磁通反向永磁电机具有较大的齿槽转矩,将导致电机产生额外的转矩脉动与振动噪声,低速工况影响更为严重。本文基于磁共能法及磁势磁导模型,首先推导了磁通反向永磁电机齿槽转矩解析模型;并在此模型的基础上,分析了电机参数对齿槽转矩波形及谐波分布的影响;提出了优选定、转子齿宽以降低齿槽转矩的方法;最后采用有限元法,以 6/8结构磁通反向电机为例,验证了分析的正确性。结果表明;随着定转子齿宽的变化,齿槽转矩各谐波分量占比也不断变化,基波分量并非一直占主导地位;通过合理选取定、转子齿宽,可以削弱特定的齿槽转矩谐波分量,进而达到抑制齿槽转矩的目的。

Due to the special doubly salient structure, flux-reversal permanent magnet (FRPM) machines normally suffer from relatively severe cogging torque, causing undesired torque ripples, as well as acoustic noise and vibration, especially at low speeds. In this paper, an analytical expression of cogging torque for FRPM machines was derived based on co-energy and magneto motive force-permeance model. Based on the derived model, the influences of design parameters on cogging torque waveform and its harmonic spectra were analyzed. Consequently, an effective method to diminish cogging torque was obtained by optimally choosing stator/rotor tooth width. Finally, with the aid of 2D finite element analysis, the above theoretical analysis and the proposed cogging torque suppression method were confirmed by 6-stator-slots/8-rotor-poles FRPM machines. The results reveal that each harmonic component of cogging torque varies greatly versus different stator/rotor tooth width, and the fundamental one doesn't always dominate. The specific harmonic component can be suppressed by optimally choosing stator/rotor tooth width, which also helps to reduce the cogging torque.