| 摘要 |
PROBLEM TO BE SOLVED: To simplify the position detection circuit of a rotor in a brushless motor, detect the position of the rotor accurately, switch current-carrying of an armature winding current properly, and improve efficiency. SOLUTION: The armature winding voltage of a brushless motor 4 is divided by the first voltage dividing circuit 10a. The divided winding voltage which is divided is divided by the second voltage dividing circuit 10b. The divided winding voltage at respective phases which is divided by the first voltage dividing circuit is compared, by a comparison circuit 10c, with 1/2 winding voltage at the remaining phases which is divided by the second voltage dividing circuit with combinations of 6 sets. By six comparative results obtained by the comparison circuit, the time of intersection of the respective divided winding voltage with 1/2 divided winding voltage is detected. Based on the difference between the detection intersection time and the previous intersection time, a time T30 corresponding to a phase of 30 degrees is calculated, correction is conducted for the time T30 according to the application of the brushless motor and present number of revolutions, and the current-carrying switching of the brushless motor is controlled at the elapsing time of the time T30 from the detection intersection time. |
