Torque Ripple Suppression of a Permanent Magnet Vernier Motor From Perspective of Shifted Air-Gap Permeance Distribution

This article proposes a method to suppress the torque ripple of the traditional V-shaped permanent magnet vernier motor (V-PMVM) from the perspective of shifted air-gap permeance distribution. On the basis of such method, a shifted permeance V-PMVM (SPV-PMVM) is presented and compared with the traditional V-PMVM. First, the generation mechanism of cogging torque as the major source of the torque ripple is explained based on the magnetic field modulation (MFM) principle. Moreover, the cogging torque expression of the SPV-PMVM is derived considering the shifted permeance design. Then, by means of the detailed and comprehensive analysis method, the key parameters of shifted permeance are optimally determined at low cogging torque and torque ripple. Finally, the SPV-PMVM and V-PMVM performances are evaluated by using the finite element method (FEM). The comparison results indicate that, based on the shifted permeance design method, the torque ripple is suppressed effectively while the desired torque output capability is maintained.