Cogging Torque Reduction of A V-Shaped PM Vernier Motor from Perspective of Airgap Permeance

In this paper, a new topology from perspective of airgap permeance, which adopts the unequal slot width (USW), is proposed to reduce the cogging torque in the V -shaped permanent magnet vernier (V-PMV) motor. Firstly, according to the magneto-motive force (MMF) permeance, the analytical expression of cogging torque for the improved motor is derived. Then, based on the theoretical analysis, the theoretical calculation angles of the slot width are obtained. In addition, the influences of the USW on electromagnetic performances, including cogging torque, back electromotive force (back-EMF), and electromagnetic torque, are investigated by finite element analysis (FEA). From the analysis results, the improved motor by employing the USW can effectively reduce the cogging torque, then make the back-EMF more sinusoidal and the torque ripple lower.