Reliability Study on Temperature Rise of Permanent Magnet Synchronous Motor Under Typical Operating Conditions of Electric Vehicles

This study takes a high-speed permanent magnet synchronous motor used in a mainstream domestic brand of electric vehicles as the experimental object. The motor is designed with five typical working conditions: constant torque, constant power, different cooling water temperatures, thermal balance under rated conditions, rated torque command and different speed combinations, and different temperature combinations of the motor stator and rotor. Temperature rise reliability tests are conducted to explore the influence mechanism of motor temperature rise and the characteristics of the influence of motor temperature rise on output torque and efficiency. The research results indicate that when the motor operates near the rated speed point, the temperature rise is most significant or severe, and the thermal equilibrium temperature is also highest; The effect of different cooling water temperatures on the temperature rise trend of the motor is not significant; The accuracy of motor output torque is mainly negatively correlated with the temperature of the permanent magnet in the motor rotor, that is, the higher the temperature of the permanent magnet, the more the motor output torque decreases.