Patent ID: 7170243
Filing Date: 2007-01-30
Classification: B62D,H02P

Abstract:
1. A drive method for a brushless motor, comprising: a first drive method in which control parameters are calculated in accordance with a deviation between a target revolution number and an actual revolution number, the revolution number of the brushless motor is controlled by a drive circuit that subjects the brushless motor to drive by a pulse width modulation (PWM) signal 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 rotation position signal of a rotation position sensor that detects a rotation position of the brushless motor; and a second drive method in which control parameters are calculated in accordance with a deviation between a target motor current value and an actual motor current value, the motor current value of the brushless motor is controlled by a drive circuit that subjects the brushless motor to drive by the PWM signal 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 that detects the motor current value of the brushless motor; wherein; when a running state of the brushless motor is in a low-load region and a high-speed revolution region, the brushless motor is driven by said first drive method, and when the running state is in a high-load region and a low-speed revolution region, the brushless motor is driven by said second drive method, a manipulated variable is computed on the basis of the calculated control parameters, an advance angle magnitude is computed on the basis of the computed manipulated variable from a prestored map that corresponds manipulated variables with advance angle magnitudes, and a value of the conduction phase angle of the drive circuit, based on either of the rotation position signal and the motor current signal, is corrected using the computed advance angle magnitude.