| 摘要 |
<p>When power is sequentially supplied to the phase coils (Lu, Lv and Lw) of a brushless DC motor (1), the rotor (42) of the brushless DC motor (1) is rotated. At this time, a voltage (V1) is induced in one of the phase coils to which power is not supplied. The rotational position of the rotor (42) is detected from the induced voltage (V1). The switching timing of power supply to the phase coils is determined in accordance with the detected rotational position. When a manual service operation mode switch (31) is operated, or detected current 20, 21 is low service operation is executed, and power supply to the respective phase coils is forcibly switched at a predetermined frequency. A failure of either motor (1) or drive circuit (3) can be diagnosed during this service operation, by measuring voltages on the circuit (3) output connector terminals (8a). <IMAGE></p> |
