Performance Comparison Between Permanent Magnet Synchronous Motor and Vernier Motor for In-Wheel Direct Drive

Abstract

Nowadays, in-wheel drive mode is considered as one of the most promising modes for electric vehicles (EVs). The motor type plays a significant role to the vehicle performances. This paper focuses on performance between permanent magnet synchronous motor (PMSM) and vernier motor (PMVM) for in-wheel direct drive. Firstly, the required performances are determined by the vehicle requirements. The prototypes of PMVM and PMSM are manufactured after the comparison. Then, the expressions of air-gap magnetic field harmonic, electromagnetic torque, and power factor are theoretically derived, where the parameter torque ratio is introduced to evaluate the torque ratio between PMVM and PMSM. Based on experiment, the back-EMF harmonics, cogging torque, maximum torque per ampere capability, flux-weakening capability, torque, efficiency, power factor, are compared and analyzed. Subsequently, the discussions are carried out, where the strength and weakness of two-type motors for in-wheel drive are concluded and the future prospects are suggested. Finally, the conclusions of two-type in-wheel motors are then extracted. This paper aims at providing a reference for the exploration of alternating in-wheel motor types, which can promote the development of high-performance in-wheel drive system for EVs.