Controller for brushless DC motor without position sensor

摘要

A controller according to one embodiment restarts the motor when a commutation timing signal is mismatched with an output pattern mode. A controller according to another embodiment compares the motor speed with the reference signal to change the chopper frequency in accordance with the compared value. A controller according to still another embodiment continuously changes the chopper frequency in accordance with the motor speed. A controller according to yet another embodiment inhibits the position detection immediately after commutation in accordance with the current flowing through the motor. A controller according to another embodiment detects the position of the rotor in accordance with the waveform of the current flowing through the motor.