Patent ID: 6049182
Filing Date: 2000-04-11
Classification: H02P

Abstract:
A motor speed control device for controlling a rotational speed of a polyphase brushless motor, said device comprising:a rotor magnetic pole position pulse signal generating circuit for generating a rotor magnetic pole position pulse signal having n pulses per one rotation of said motor, n being an integer greater than 1 and being an integral multiple of the number of driving magnetic poles of said motor;a rotational pulse signal generating circuit for generating a rotational pulse signal indicating the number of rotations of said motor and having m pulses per one rotation of said motor, m being an integer greater than n;a rotational angle detector for detecting rotational angle information indicating a rotational angle of said motor, based on the rotor magnetic pole position pulse signal and the rotational pulse signal;a torque ripple corrective memory for preliminarily storing a data stream for correcting a torque ripple of said motor, reading out a data corresponding to the rotational angle information from the data stream, and outputting the data as a torque ripple corrective signal; anda correction circuit for using the torque ripple corrective signal in conjunction with a motor control signal for controlling the rotational speed of said motor so as to correct the motor control signal.