Rotor temperature monitoring method and system for permanent magnet synchronous motor

A rotor temperature monitoring method and system for a permanent magnet synchronous motor. According to the method and system, an a-phase line current and a b-phase line current of a stator of a permanent magnet synchronous motor are obtained as a first line current and a second line current (S101); further, a line voltage between the a phase and the b phase of the stator is obtained (S102) and a rotating speed of the rotor of the permanent magnet synchronous motor is obtained (S103); and then, the first line current, the second line current, the line voltage, the rotating speed of the rotor, an inductance parameter of the permanent magnet synchronous motor and a temperature characteristic equation of a permanent magnet of the rotor are substituted into a preset rotor permanent magnet temperature expression to calculate and obtain the temperature of the rotor (S104). By means of the rotor temperature monitoring method and system, it is unnecessary to embed a temperature sensor in the rotor to monitor the temperature of the permanent magnet of the rotor, thereby avoiding the problem of low system reliability due to the configuration of the temperature sensor to monitor the temperature of the permanent magnet of the rotor.