| 摘要 |
PROBLEM TO BE SOLVED: To prevent step-out and enable operation with desired efficiency. SOLUTION: A potential difference signal is detected which indicates the potential difference between the neutral point of armature coils 1a, 1b, 1c and the neutral point of a three-phase Y-connected resistor circuit 2 in the parallel state to the armature coils 1a, 1b, 1c. The potential difference signal is integrated with an integrator 22. On the basis of the integrated signal, the rotation position of the armature 1 is detected. Whether the level of the integrated signal is higher than or equal to a target value obtained by smoothing a PWM signal having a desired duty ratio is detected with a level detector 6. On the basis of the rotation position, a voltage pattern is changed over. On the basis of the detected result, the time to elapse until the voltage pattern is changed over from a position signal is adjusted by a correcting means, in such a manner that the level of the integrated signal becomes a target value. |
