| 摘要 |
<p>PURPOSE:To suppress the lowering of accelerating property, by quickening the making time of working signal to a field-weakening circuit according to the lowering of line voltage. CONSTITUTION:By a delay circuit 21, the respective output signals of a current detection circuit 17 and a conductivity detection circuit 19 are received and at a fixed time later, after a by-pass contactor 13 is turned ON, by the field- weakening control making command of a field-weakening control making circuit 23, a field-weakening contactor 7 is turned ON. Then, field current flowing to a field winding 3 is reduced and a field is weakened and so the rotation of a motor is heightened. In this case, the delay circuit 21 is worked so that a working signal making time to a field-weakening circuit 10 may be quickened according to the lowering of a voltage value detected by a voltage detection circuit 27. As a result, even if the voltage value of a main power source is lowered, the lowering of accelerating property can be suppressed.</p> |
