Effect of rotor surface auxiliary slot on cogging torque of PMSM

ZHANG Zeyu1,2, JIAO Zhiyong1, XIA Hongbing2, ZHAO Peng1, SU Shijian1,2

(1.School of Mechanical Engineering, Tianjin University of Science and Technology, Tianjin 300222, China;

2.Automotive Engineering Research Institute, China Automotive Technology

and Research Center Co., Ltd., Tianjin 300300, China）

Abstract: Aiming at the vibration and noise problem of permanent magnet synchronous motor caused by high cogging torque, the structure of auxiliary slot on rotor surface was optimized. Through the principle of permanent magnet synchronous motor cogging torque, the influence of rotor structure on motor cogging torque was analyzed, and the relationship between the structure of the auxiliary slot on the rotor surface and the cogging torque of the motor was discussed. A permanent magnet synchronous motor model with 8 poles and 48 slots was built by finite element method. With the builtin permanent magnet synchronous motor model as the carrier, by changing the air gap flux density harmonic component, multiobjective genetic algorithm was used to calculate the optimal solution of the number, position and depth of the auxiliary slot, and the optimal design scheme of the auxiliary slot structure was obtained. The results indicate that the cogging torque of the builtin permanent magnet synchronous motor can be effectively reduced by using the optimized rotor surface auxiliary slot structure and increase the amplitude of airgap magnetic dense basis, and reduce the amplitude of 5th and 7th harmonics. The peak torque of the cogging slot is reduced by 76.2%, and the motor performance is not reduced.