Research on the Influence and Weakening of Pole-Arc Coefficient on Cogging Torque in Consequent-Pole Permanent Magnet Synchronous Motors

The consequent-pole permanent magnet synchronous motor (CPPM) has flexible pole arc coefficients. However, the pole arc coefficient significantly influence the cogging torque. In this article, the relationship between the pole arc coefficient and cogging torque of CPPM was derived by establishing a Fourier series analytical expression for the unit airgap magnetic permeability and the rotor permanent magnet magnetic excitation using the energy method. Firstly, the equivalent magnetic circuit model of CPPM was established using magnetic circuit analysis and Fourier series methods, and the influence of the pole arc coefficient on the cogging torque was analyzed. By using an unequal pole arc coefficient combination and skew slots, the cogging torque could be weakened. Secondly, through finite element simulation analysis, the cogging torque of different pole arc coefficients and unequal pole arc coefficient combinations were compared to verify the effectiveness of the proposed methods for reducing the influence of the pole arc coefficient on the cogging torque.