Optimal Pole Ratio of Spoke-type Permanent Magnet Vernier Machines for Direct-drive Applications  

作　　者：Yu Zhao Dawei Li Xiang Ren Ronghai Qu Jianbo Sun Ping Yu 

机构地区：[1]the State Key Laboratory of Advanced Electromagnetic Engineering and Technology,School of Electrical and Electronic Engineering,Huazhong University of Science and Technology,Wuhan,430074,China [2]IEEE [3]the Jing-Jin Electric Technology (Zhengding) Co., Ltd

出　　处：《CES Transactions on Electrical Machines and Systems》2022年第4期454-464,共11页中国电工技术学会电机与系统学报（英文）

基　　金：supported in part by the National Nature Science Foundation of China(NSFC)under Project 51977094;in part by the National Key Research and Development Program of China under Grant 2017YFB0102400。

摘　　要：Due to magnetic gearing effects,spoke-type permanent magnet vernier machines(ST-PMVMs)have the merit of high torque density,where an extra torque amplification coefficient,i.e.,pole ratio(the pole-pair ratio of PMs to armature windings)is introduced.However,different from surface-mounted PMVM,the variation of torque against pole ratio in ST-PMVMs is non-linear,which is increased at first and then decreased.This article is devoted to identify the optimal pole ratio of ST-PMVMs by equivalent magnetic circuit model.It is found that except the Prth air-gap magnetomotive force(MMF)harmonic having the same pole-pair of PM,the Path air-gap MMF harmonic having the same pole-pair of armature winding is also induced due to the modulation of doubly salient air-gap structure.The Prth MMF harmonic produces positive torque,while Path MMF harmonic produces negative torque.With the increase of pole ratio,the proportion of Path MMF harmonic as well as negative torque is increased,which reduces the advantages of high pole ratio coefficient.Further,the influence of dimension parameters on the performance of ST-PMVMs under different pole ratio are investigated.Results show that ST-PMVMs with pole ratio 2.6 have high torque density,low cogging torque and high power factor simultaneously.Finally,a prototype is manufactured to validate the analysis.

关 键 词：Spoke-type permanent magnet machines(ST-PMVMs) Pole ratio Back electromagnetic force(EMF)and torque capability 

分 类 号：TM351[电气工程—电机]