| 摘要 |
<p>The traction motor is normally under the control of a chopper, and is connected to the supply by the chopper and a contactor. The field winding is regulated by a controller also connected between supply lines, and the field to armature common point lies near the negative potential line. For braking duty, either dynamic or resistive, the contactor is opened. The potential at the field to armature common now lies close to the positive line due to the forward bias of the diode between the common point and the positive supply caused by the freewheel current of the motor. In consequence the field current reverses and is followed by armature potential reversal.</p> |
