Influence of the magnetic pole shape on the cogging torque of permanent magnet synchronous motor

Aiming at the problem of the permanent magnet synchronous motor (PMSM) vibration, noise and poor control precision caused by the cogging torque, the influence of different pole shapes on the motor electromagnetic field was studied. Based on the FEM, the effects of two types of the magnetic poles with different eccentricity on the magnetic field and induced electromotive force (EMF) are studied. The relationship between the magnetic poles shapes, the magnetic field and the induced EMF is obtained. Secondly, based on the Fourier decomposition theory, the air gap flux density harmonic content and the induced EMF are studied. The influence mechanism of the magnetic pole shape on the air gap flux density and the induced EMF is revealed. Finally, the cogging torque of the PMSM with different magnetic poles is studied, and the influence of different magnetic pole shape on the cogging torque is obtained. By optimising the shape of the magnetic pole, the maximum fluctuation amplitude of the cogging torque is reduced by 80.4%. The motor cogging torque can be effectively weakened by the PM eccentric design. This work lays a theoretical foundation for the study of cogging torque. © 2018, © 2018 Engineers Australia.