定子无磁轭模块化轴向永磁电机磁极表面开槽分析

在永磁电机设计中,永磁体(PM)作为励磁磁源,直接影响电机性能。由于定子电流时间谐波和气隙磁场中高次空间谐波的存在,永磁体内产生的涡流损耗不容忽视,极易导致永磁体过热或不可恢复性退磁。本文提出一种减小定子无磁轭模块化轴向永磁电机永磁体涡流损耗的方法,以一台10极、12槽、20k W的轴向永磁电机为例,通过对永磁体表面开槽深度、开槽方式及开槽数目的研究,利用解析法和三维有限元仿真分析不同开槽结构的永磁体涡流损耗,推导出永磁体涡流损耗等解析式。并对比带额定负载时气隙磁通密度,合理选择永磁体表面开槽方式及开槽数目。

Analysis on Magnet Surface Groove of Yokeless and Segmented Armature Axial Flux Motor

The permanent magnets (PMs) are the magnetic excitation source in the permanent magnet synchronous motor (PMSM). It could seriously affect the performance of the PMSM. Due to time harmonics of stator current and high-order space harmonics of air gap magnetic field, the loss in permanent magnets is considerable and is easy to cause the partial over-temperature. As a result, the irreversible demagnetization of permanent magnets is occurred with poor cooling condition. This paper discusses a way to reduce the magnet eddy current loss. Herein, a yokeless and segmented armature (YASA) axial flux PMSM is taken as an example, where its parameters are 10 poles, 12 stator segments and 20kW. In order to reduce the magnet eddy current loss, the influences of several factors were studied including the groove depth, groove method and groove number. The expression of magnet eddy current loss and other parameters were calculated respectively. And then the calculated results from the analytic method were compared with those calculated by three dimensional finite element method. Compared with the air gap flux density of the rated load, the reasonable way and number of magnet surface groove were chosen.