Estimation method and estimation system for motor output torque of electric vehicle driving system

The invention discloses a motor output torque estimation method and system for an electric vehicle driving system, and the method comprises the steps: calculating the duty ratio value of a PWM signal through collecting the cumulative time of a certain level state of the PWM signal outputted by an IGBT driving module in the electric vehicle driving system in each PWM signal period, reconstructing a three-phase phase voltage value of the motor according to the duty ratio value of the PWM signal; in each PWM signal period, collecting a three-phase current value of the motor; acquisition of the cumulative time of a certain level state of the PWM signal and acquisition of the three-phase current value of the motor are triggered and collected through the same trigger signal, and the period of the trigger signal is consistent with that of the PWM signal. And calculating a real-time electric power value of the driving system according to the three-phase voltage value and the three-phase current value, and estimating