Optimization Design of Cogging Torque and Back EMF Waveform for PMSM

CNC equipments require the motor to output smooth torque, while cogging torque is one of the main factors that affect the motor torque fluctuation. In this paper, the reason of cogging torque in PMSM was analyzed first, and the effects of notch width and closed slot structure on cogging torque were studied by FEM. Then, the height of bridge arc was designed by use of optimal design method to improve the sin degree of the back EMF waveform. Finally, the rationality of the design was verified by the no-load test of the prototype.