Accurate Prediction of Efficiency Region of Permanent Magnet Machines Based on Magnetic-Thermal Coupling

The operating temperature of the motor has a significant impact on electromagnetic performance, which affects in efficiency prediction. This article adopts a magnetic thermal bidirectional coupling method to obtain accurate operating temperature and corresponding electromagnetic performance with the consideration of dynamic changes of material thermal characteristics. Based on the results of finite element analysis (FEA), a dependence factor is developed to compare the different temperature dependencies of the motor loss and torque. Then, the relationship that the highest efficiency point of the motor under different working conditions occurs at different temperatures is obtained, which can provide guidance for the design of motor heat dissipation system. Finally, an efficiency prediction model considering temperature is established, and improve the accuracy comparing with the traditional method.