APPARATUS AND METHOD OF REGULATING THE SPEED OF A DC BRUSHLESS MOTOR

摘要

A control circuit (100) for regulating the rotational speed of a DC brushless motor (102) includes an electrical conduction switch (130) having an input (132), an output (134) and a control terminal (156) for passing a motor supply signal to a DC brushless motor. A voltage averaging circuit (136, 138) generates an averaged signal indicative of the average voltage level being supplied to the motor. The averaging circuit informs an error amplifier (146) to modulate the motor supply signal to compensate for changes in the voltage level of the motor supply signal in order to maintain the rotational speed of the motor at a generally constant rpm. The control circuit (100) takes advantage of the motor windings (106, 108) and rotor mass as a filter circuit to smooth changes in current drawn by the motor, and to further maintain the rotational speed of the motor.