{"title":"Optimal Pole Ratio of Spoke-type Permanent Magnet Vernier Machines for Direct-drive Applications","authors":"Yu Zhao;Dawei Li;Xiang Ren;Ronghai Qu;Jianbo Sun;Ping Yu","doi":"10.30941/CESTEMS.2022.00057","DOIUrl":null,"url":null,"abstract":"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 P\n<inf>r</inf>\n<sup>th</sup>\n air-gap magnetomotive force (MMF) harmonic having the same pole-pair of PM, the Pa\n<sup>th</sup>\nair-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 P\n<inf>r</inf>\n<sup>th</sup>\n MMF harmonic produces positive torque, while Pa\n<sup>th</sup>\nMMF harmonic produces negative torque. With the increase of pole ratio, the proportion of Pa\n<sup>th</sup>\nMMF 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.","PeriodicalId":100229,"journal":{"name":"CES Transactions on Electrical Machines and Systems","volume":null,"pages":null},"PeriodicalIF":0.0000,"publicationDate":"2022-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/iel7/7873789/10004905/10004928.pdf","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"CES Transactions on Electrical Machines and Systems","FirstCategoryId":"1085","ListUrlMain":"https://ieeexplore.ieee.org/document/10004928/","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 0
Abstract
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 P
rth
air-gap magnetomotive force (MMF) harmonic having the same pole-pair of PM, the Pa
th
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 P
rth
MMF harmonic produces positive torque, while Pa
th
MMF harmonic produces negative torque. With the increase of pole ratio, the proportion of Pa
th
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.