A new method for reducing cogging torque of brushless dc motor in integrated motor propulsor

The cogging torque of brushless DC motor for integrated motor propulsor can seriously affect the performance of integrated motor propulsor. To deal with this problem, this paper considers the requirements of the propulsor's size, processing technology and performance, and presents a slot opening skew comprehensive optimization method to reduce the cogging torque and minimize its influence on the output torque. Using Box-Behnken to design experiments and response surface methodology (RSM) to process experimental data, a mathematical model about the relationship among the angle of slot opening skew, pole-arc coefficient and slot opening width is obtained. Moreover, the optimal combination of the slot opening skew angle, pole-arc coefficient and slot opening width is determined. The electromagnetic field analysis software infolytica/MagNet is used to solve the values at various experimental sites and verify the optimal combination forecast. The results show that for the 2 kW motor designed for this study, when the angle of slot opening skew is 5°, the pole-arc coefficient is 0.65 and the slot opening width is 3 mm, the cogging torque is reduced by about 28.69%.