Analysis and Design Optimization of V-Shaped Permanent Magnet Vernier Motor for Torque Density Improvement

Abstract

This paper presents an inner rotor vernier motor featuring the V-shaped permanent magnet (PM) rotor topology; the torque performance of the proposed motor is compared to that of a conventional V-Shaped interior PM motor. The volume of the proposed motor is kept 35% lower than that of the conventional motor. The equations of back electromotive force and reactance are presented, and the air gap flux densities and flux density distributions of both motors are analyzed and compared. A 2D finite element analysis is conducted at three different operating speeds in order to investigate the performance of both motors. The torque components indicate that the proposed motor achieves superior torque performance (i.e., higher average torque and lower torque ripple) at a reduced volume, for the same input current density. Moreover, the torque-current angle characteristic curves at different current densities are obtained and compared. The losses, efficiencies, and power factors of both motors are compared and discussed. Finally, multi-objective optimization of the proposed vernier motor is carried out to further enhance its performance. The results of the analysis prove that the proposed motor achieves better torque density owing to the vernier effect and superior torque performance due to the V-shaped rotor topology.