A Calculation Method for the On-Load Cogging Torque of Permanent Magnet Synchronous Machine

Abstract

This paper presents a new method to calculate the cogging torque of the permanent magnet synchronous machine under load condition. Combined with the mathematical expression of the cogging torque, it is found that the cogging torque will be influenced by the load. In order to accurately analyze the torque ripple of the motor at low speed and high torque operation and make it possible to reduce the cogging torque under load condition, it is necessary to calculate the cogging torque accurately. A calculation method for the on-load cogging torque of the PMSM, which the cross magnetization and core saturation have been taken into consideration, is proposed in this paper. The finite element analysis (FEA) and field-oriented control (FOC) contribute to the method, which mainly consists of three parts: elimination of the reluctance torque, calculation of the average torque, and the ripple torque and the separation of the cogging torque. By using this method, the cogging torques of a 16-pole/24-slot PMSM under different load conditions has been calculated. The result shows a very good agreement between simulation and experiment, which verifies the feasibility and effectiveness of the proposed method.