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

Hamza Ahmad,Jongsuk Ro

doi:10.1109/access.2021.3052258

Hamza Ahmad, Jongsuk Ro

Open Access

https://doi.org/10.1109/access.2021.3052258

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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.

Highlights

Owing to advantages such as a high torque density and a compact mechanical structure, vernier permanent magnet (VPM) motors have attracted significant research interest [1]–[3]
Reference [39] presents a comparison of a V-shaped interior permanent magnet (IPM) machine (VIM) and a surface-mounted PM machine; the results indicate that the VIM has lower eddy current losses and a wider constant power speed range
This study proposes an inner rotor V-shaped IPM vernier motor (VIVM) as a potential alternative to conventional VIMs which are widely used in hybrid electric vehicles

Summary

INTRODUCTION

Owing to advantages such as a high torque density and a compact mechanical structure, vernier permanent magnet (VPM) motors have attracted significant research interest [1]–[3]. Using long end winding turns with integral slot-distributed windings in conventional VPM machines can result in complications; these long end windings occupy a significant portion of the volume of the machine, thereby the advantage of a higher torque density is remunerated To resolve this problem, toroidal winding and non-overlapping windings have been employed [24]–[26]; for the application of these winding arrangements, modifications in the stator topology are required. It can be seen that the motor has an interior rotor structure; its dimensions are illustrated, indicating the major design variables associated with the conventional motor This motor is a 4-pole, 12-slot machine with a distributed full pitch winding. When designing a VPM, the combination is selected such that the change in geometry, as compared to that of conventional motors, is minimal; this is to ensure that the comparison is fair and valid

EQUIVALENT CIRCUIT PARAMETERS

Findings

CONCLUSION