STUDY OF COGGING TORQUE IN LINE-START PERMANENT MAGNET SYNCHRONOUS MOTORS

Due to the interaction between the permanent magnet and slotted armature lamination,there exists cogging torque in slotted permanent magnet motors,which may cause noise and vibration.In this paper,a novel method was proposed to analyze the cogging torque for line-start permanent magnet synchronous motors,and the expression of cogging torque was deduced.Being based on expression and the difference of production mechanism,the components of the cogging torque are classified into four classes.The characteristic for every class is analyzed,and effects of skewing are studied.It was shown that not all the cogging torque components in line-start permanent magnet synchronous motor can be eliminated by skewing,which is different from surface-mounted permanent magnet motors.