| 摘要 |
<p>PURPOSE:To prevent a current from rapidly varying by operating a field controller after becoming a field weakening range, and not securing the phase of a thyristor to a constant value at field weakening time. CONSTITUTION:When a main circuit contactor 7 is closed at power drive time, a field weakening contactor 8 is not closed, and a field controller 6 is not operated. Accordingly, it becomes a full field operation. As the speed rises, the resistance of a resistor 5 is sequentially shortcircuited. When all resistor is shortcircuited. The field weakening contactor 8 is closed, and the controller 6 is operated. At this time the phase control angle of a thyristor of the controller 6 is not secured to the constant value, but set to an activated state, and when the contactor 8 is closed, it can be momentarily shifted to the most optimum phase control angle.</p> |
