| 摘要 |
<p>A pulse control circuit for a d.c. series motor 10 having an armature 12 and two oppositely-wound field windings 14F and 14R, comprises a contactor 8 in series with the motor 10, two main thyristors 22F and 22R each connected in series with the armature and a respective one of the field windings, means for controlling the mark-to-space ratio of conduction of each main thyristor, one or other of the main thyristors being brought into operation in dependence upon the desired direction of drive of the armature, means 42 for sensing failure of commutation of the main thyristor 22F or 22R, and means for causing opening of the contactor 8 in response to such sensing. The control circuit includes means for firing the other main thyristor 22R or 22F immediately commutation failure is sensed, thereby to limit the net field flux and motor torque in the period during which the contactor 8 is opening.</p> |
