Cogging Torque Analysis And Weakening Method Research Of Permanent Magnet Synchronous Motor For New Energy Vehicles

With the round of automobile energy revolution,traditional internal combustion engine vehicle(ICEV)will be gradually replaced by electric vehicle(EV),and the vehicle drive motor is the core part of EV.Because of its high torque density,low loss and wide speed range,interior permanent magnet synchronous motor(IPMSM)is widely used in new energy vehicles.However,as a common problem in PM motors,cogging torque can cause the noise and vibration.With the development of research,the weakening of cogging torque has been one of the hot issues,which concerned by domestic and foreign experts and scholars.This paper analyzes the generation mechanism of cogging torque in PMSMs,and obtains the mathematical expression of cogging torque.Combining with the characteristics of V-type IPMSM,two methods of optimizing pole-arc coefficient and symmetry are proposed to reduce cogging torque.Finally,the feasibility of the proposed methods is verified by finite element simulation(FEM)and its influence on the overall performance of the motor is analyzed.The main research work in this paper is described as follows:(1)The basic structure and mathematical models of PMSM in different coordinate systems are introduced.The generation mechanism of cogging torque in PMSM is analyzed from different perspectives,and the mathematical expression of cogging torque is obtained based on the energy method.(2)A parametric model of the pole-arc coefficient in V-type IPMSM is established,and a method is proposed to reduce the cogging torque by making the pole-arc coefficient of the motor reach the theoretical optimal value through rotor modification.(3)By optimizing the PMSMs' rotor parameters to improve the cogging torque symmetry,and combining rotor step-skew method,a universally applicable method is proposed,which can eliminate the IPMSM's cogging torque effectively.(4)By comparing with the other three PMSMs,the electromagnetic performance of the optimized V-type IPMSM is further evaluated,so as to verify the practicability of the proposed method in the PMSM for new energy vehicles.