余弦削极转子磁通切换永磁电机设计与性能分析

Design and Performance Analysis of Flux-switching Permanent Magnet Machine With Cos-chamfering Rotor

磁通切换永磁(flux-switching permanent magnet,FSPM)电机具有功率密度高、转子结构坚固、永磁体冷却条件优越等优点,在工业领域应用潜力巨大。然而,由于双凸极结构和较高的气隙磁密,FSPM电机的齿槽转矩和转矩波动较大,严重限制了其在伺服领域的应用。该文首先介绍FSPM电机气隙磁场调制机理,分析气隙磁场中不同谐波对转矩的贡献;进而,以一台定子12槽、转子10极电机为研究对象,提出一种抑制气隙磁场高频谐波分量的余弦削极转子结构,通过转矩优化确定最优转子结构参数;然后基于有限元分析,对比采用传统凸极转子和余弦削极转子的两台FSPM电机磁场分布、齿槽转矩、反电动势和转矩特性。最后,仿真和样机实验结果表明,所提余弦削极转子可有效降低FSPM电机齿槽转矩和转矩波动,齿槽转矩降低93.9%,转矩波动降低91.4%,扩宽了FSPM电机的应用领域,并为其他双凸极结构电机齿槽转矩及转矩波动的抑制提供了新思路。

Flux-switching permanent magnet(FSPM)machines,with high power density,robust rotor structure,and favorable PM cooling capacity,are a promising candidate in the industrial field.However,due to the double salient structure and high air-gap flux density caused by PMs,FSPM machines suffer from high cogging torque and torque ripple,restricting their application in servo systems.In this paper,the air-gap magnetic field modulation mechanism of FSPM machines was introduced first,and the contributions of harmonics to electromagnetic torque were analyzed.Then,taking a 12/10FSPM machine as an example,a cos-chamfering rotor,which can suppress high-frequency harmonics of the air-gap magnetic field,was proposed.Besides,the optimal rotor parameters were determined by torque optimization.Moreover,based on finite element analysis,the key characteristics of two FSPM machines with the traditional salient-pole rotor and the proposed cos-chamfering rotor were compared,including magnetic field distribution,cogging torque,back electromotive force,and torque.Finally,the simulation and prototype experimental results show that the suppression ratio of the cos-chamfering rotor on cogging torque and torque ripple of the FSPM machine could achieve 93.9%and 91.4%,respectively,which broadens the application fields and provides new methods of cogging torque and torque ripple suppression to other doubly salient-pole machines.