Patent ID: 6476576
Filing Date: 2002-11-05
Classification: H02P

Abstract:
A motor control apparatus comprising:a servo circuit for outputting a pulse width modulation signal; a low-pass filter for receiving said pulse width modulation signal outputted by said servo circuit as an input; a driver circuit for receiving an output voltage of said low-pass filter as an input and thereby driving a brushless sensorless motor; and rotational speed changing means for changing rotational speed of said motor by gradually varying a voltage outputted by said driver circuit from a current voltage to a target voltage on input of a control start signal; wherein said servo circuit controls pulse width of said pulse width modulation signal so as to maintain the rotational speed of said motor at a target rotational speed on the basis of an FG pulse signal outputted by said motor, the FG pulse signal representing the rotational speed of said motor by frequency.