Analysis and Reduction of Cogging Torque in Dual PM Vernier Machine with Irregular Split Teeth

This paper investigates the performances of dual PM split tooth vernier machines (DP-STVMs). It has been proved that by adjusting the distribution of stator auxiliary teeth, the flux modulation effect and no-load back EMF of DP-STVMs can be enhanced. However, this irregular structure also changes the periodicity and increases the amplitude of cogging torque. To investigate the source of cogging torque in DP-STVMs, an analytical method based on airgap fields and Maxwell stress tenser method is used, which can easily present the contribution of each airgap field component to the cogging torque. Based on the analysis, novel cogging torque reduction methods are proposed in this paper. Compared to regular rotor skewing method, the proposed methods can achieve better suppression effect on cogging torque and less reduction on noload back EMF.