转子分段移位斜极的永磁同步电机轴向电磁力分析

Analysis of Axial Electromagnetic Force in Permanent Magnet Synchronous Motor with Rotor Shift Step Skewing

永磁体转子分段移位斜极有效抑制了电机的齿槽效应,也可能产生额外的不平衡轴向电磁力,永磁体转子分段移位斜极方法已成为研发高品质永磁同步电机的关键技术。基于轴向电磁力的解析式,解析了永磁同步电机轴向电磁力产生的机理。以一台48槽8极永磁同步电机为例,进行永磁同步电机轴向电磁力的三维有限元仿真实验与抑制技术研究,结果表明,永磁同步电机轴向电磁力主要由绕组端部漏磁和转子永磁体移位斜极漏磁引起,且后者占主要部分;转子线性移位斜极分段数的增多,可减小谐波磁场影响,但移位斜极漏磁随之增大,导致轴向电磁力增大;相同移位斜极分段数的不同拓扑结构,其轴向电磁力幅值差异较大,反对称结构的轴向电磁力由于沿轴向中心面反对称分布,可有效抑制轴向电磁力,其中V形反对称结构效果最佳。

The permanent magnet rotor shift step skewing effectively suppress the slot effect of the motor,and may also generate additional unbalanced axial electromagnetic force.The rotor shift step skewing method of permanent magnet has become a key technology for the development of high-performance permanent magnet synchronous motor.Based on the analytical formula of axial electromagnetic force,the mechanism of axial electromagnetic force generation of permanent magnet synchronous motor(PMSM)was analyzed.Taking a 48-slot 8-pole permanent magnet synchronous motor as an example,the three-dimensional finite element simulation experiment of the axial electromagnetic force of the PMSM was carried out and the suppression technology was studied.The results show that the axial electromagnetic force of PMSM is mainly caused by magnetic flux leakage at the end of winding and the permanent magnet shift magnetic flux leakage.The influence of harmonic magnetic field can be reduced by increasing the number of segments of the shifted oblique pole,but the magnetic flux leakage of the shifted oblique pole increases with it,resulting in the increase of axial electromagnetic force.The axial electromagnetic force amplitude of different topologies with the same segment number of shifted oblique poles is greatly different,and the axial electromagnetic force of the anti-symmetric structure can be effectively suppressed due to the anti-symmetric distribution along the axial central plane,among which the v-type anti-symmetric structure has the best effect.