Motor rotating speed measuring method, controller and motor

The invention discloses a motor rotating speed measuring method, a controller and a motor, and the motor rotating speed measuring method comprises the steps: obtaining the time interval of adjacent pulsating current peak values according to the pulsating current of the motor, the pulse current waveform between the adjacent pulse current peak values comprises the commutation current waveform of the first magnetic pole and the commutation current waveform of the second magnetic pole, and the time point at which the commutation current of the first magnetic pole starts to increase is earlier than the time point at which the commutation current of the second magnetic pole starts to decrease; obtaining a rotating speed sequence of the motor according to the time interval of the adjacent pulsating current peak values and the number of commutator segments of the motor; and obtaining the motor speed according to the speed sequence. According to the method for measuring the rotating speed of the motor, the precision requirement for data acquisition equipment is reduced, meanwhile, no extra speed measurement equipment needs to be added in the motor, the manufacturing cost of the motor is reduced, and a complicated structure in the motor is avoided.