Performance Improvement of Surface Permanent Magnet Vernier Motor by Adjusting Current Control Angle Considering Magnetic Saturation

Surface permanent magnet vernier motors (SP-MVMs) possess the characteristics of high torque density and simple structure, making them a compelling technology for gearless applications, such as in-wheel motors and robots. This paper investigates the impact of current control angle on the magnetic saturation at the rated operating point for SPMVMs. The magnetic saturation analysis is conducted on motors with various magnet thickness to identify the effect of magnetic saturation level on the performance metrics. Focus is placed on selecting the optimal current angle to achieve both high torque density and power factor at the rated point. It shows that SPMVMs with small magnet thickness exhibit higher torque density and power factor simultaneously than those with thick magnet, if appropriate current control angle is set at the rated operating point. Moreover, the selection of the current angle has no significant impact on the flux weakening capability. This finding can be used to define the optimal current control angle of SPMVMs at the rated operating point for improved performance and reduced power burden on the inverter. The simulation results show that a high torque density of 23 Nm/L and a high power factor of 0.92 is achieved. Part of the experiment has been conducted for SPMVMs.