METHOD AND APPARATUS FOR DETECTING ROTATIONAL SPEED OF MOTOR

摘要

PROBLEM TO BE SOLVED: To accurately find out a rotational speed when a rotational frequency of a motor is changed such as acceleration/deceleration of the motor.SOLUTION: In a motor rotational speed detecting method for extracting rotational positions of a rotor of a motor M at a predetermined interval and finding out the rotational speed of the motor on the basis of the extracted rotational positions, the acceleration of the motor M is found out and the interval for extracting rotational positions is changed in accordance with the found acceleration. A speed calculation value of the motor M is found from the rotational positions by applying a finite difference method and the acceleration of the motor M is found based on the found speed calculation value. A motor physical model capable of calculating the acceleration of the motor is previously set from a current value of the motor M and the acceleration of the motor M is found out by applying the current value of the motor M to the physical model.