Abstract
The load capacity of the permanent magnet synchronous motor is limited by the rotor temperature, and the excessive temperature of the rotor will bring potential thermal safety problems of the system. Therefore, the accurate prediction of the rotor temperature of the permanent magnet synchronous motor for the electric vehicle is crucial to improve the motor performance and system operation safety. This paper studied the heating mechanism and the energy flow path of the motor and built the heat energy conversion model of the stator and rotor. The real-time algorithm to predict the rotor temperature was constructed based on the dissipative energy conservation of the stator of the motor rotor temperature. And the prediction method of the initial rotor temperature is fitted using the experimental results when the system is powered on. Finally, the test platform was set up to validate the rotor temperature accuracy. The results show that the motor rotor temperature estimation error under the dynamic operating condition is within ±5. The research provides a solution to improve the performance and thermal safety of the permanent magnet synchronous motor for electric vehicles.
Highlights
E copper and the iron losses are the main sources for the temperature rise of rotor magnetic steel, and the temperature of rotor magnetic steel directly determines the duration of the peak power of the motor. erefore, the research of the rotor temperature prediction can ensure the thermal safety of the motor and improve the peak performance of the motor
The torque capacity of permanent magnet synchronous motor (PMSM) is usually lower than its actual torque capacity to avoid overheating failure of the motor without the high-precision rotor temperature prediction [4, 5]
When the vehicle is powered on, initial rotor temperature can be attained by adopting the previous rotor temperature Tr−pre, the stop time tstop, and the environment temperature Ten as the following steps: (1) Obtain the value of Tr−pre and tstop which are saved in electrically erasable programmable read-only memory (EEPROM) of the motor controller last time
Summary
E copper and the iron losses are the main sources for the temperature rise of rotor magnetic steel, and the temperature of rotor magnetic steel directly determines the duration of the peak power of the motor. erefore, the research of the rotor temperature prediction can ensure the thermal safety of the motor and improve the peak performance of the motor. It is difficult to obtain the temperature of rotor magnetic steel by direct measurement when the motor is running [6]. E rotor temperature measurement methods include sliding ring and wireless temperature sensor. These two methods have high cost and low engineering feasibility, so they cannot be applied in batch. The rotor temperature prediction methods mainly include three directions. The initial temperature of the rotor cannot be assigned to calculate when the system is powered up again It only predicts the rotor temperature under normal temperature conditions without considering the influence of ambient temperature on the rotor temperature characteristics, resulting in poor adaptability and limited accuracy of the algorithm [15]. When measuring the rotor temperature with the counterelectromotive force method, the motor current should be unloaded. It is not practical to predict the real working condition of the vehicle
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