| 摘要 |
PROBLEM TO BE SOLVED: To make it possible to perform adequate current-conduction switching all the time regardless of the change in the number of rotations of a brushless motor and to achieve the low cost of a control circuit and a compact configuration of a control board. SOLUTION: A DC power supply Vcc is switched, and the voltage is applied on this motor 1. The conducting state of the armature-winding current of the motor 1 is changed, and the rotation is controlled. At this time, the DC power supply Vcc and one winding voltage R of the armature windings of the motor 1 are inputted into an isolator part 10. The isolator part 10 obtains the voltage waveform (voltage waveform obtained by inverting the winding voltage) of the DC voltage Vcc observed with the winding voltage R as the reference and aligns the level of the winding voltage having this voltage waveform with the grounding potential. A comparing circuit 11 compares the voltage waveform obtained with the isolator part 10 and the grounding potential winding voltage R observed with the grounding potential as the reference and outputs the result of comparison to a control circuit 12. The control circuit 12 detects the same-potential point (intersecting point (neutral point; position detecting point)) of each voltage waveform from the result of the comparison, counts the time from the conduction change to the same potential point and computes the time to conduction change from counted time. |
