Patent ID: 7157870

Claim:
A drive method for a brushless motor wherein a motor current value of the brushless motor is controlled by a drive circuit which calculates control parameters in accordance with a deviation between a target motor current value and an actual motor current value and which performs drive of PWM on the basis of the calculated control parameters, and wherein a conduction phase angle of the drive circuit is controlled on the basis of a motor current signal of a motor current detection sensor which detects the motor current value of the brushless motor; comprising the steps of computing a manipulated variable on the basis of the calculated control parameters, computing an advance angle magnitude from a corresponding relationship between a manipulated variable and an advance angle as designed and created beforehand, on the basis of the computed manipulated variable, and correcting a value of the conduction phase angle of the drive circuit as set on the basis of the motor current signal, with information of the computed advance angle magnitude.