METHOD FOR DETECTING THE ROTATIONAL POSITION OF THE DRIVE SHAFT OF A DC MOTOR

摘要

A method for determining the rotational position of the drive shaft of a DC motor includes providing a period of a reference current ripple indicative of proper operation of the motor. The period of the reference current ripple is then compared with the period of each current ripple contained in a rotor current signal of the motor during operation of the motor. The current ripples of the rotor current signal of the motor having periods which differ from the period of the reference current ripple are then corrected. A corrected rotor current signal based on the corrected current ripples and uncorrected current ripples of the rotor current signal of the motor is then generated. The current ripples contained in the corrected rotor current signal are then counted to determine the position of the drive shaft of the motor and, consequently, the position of an element being driven by the motor.