| 摘要 |
A control circuit for a d.c. motor (M) fed by a full-wave rectifier comprises a controlled current semiconducting element connected between the rectifier and the motor. The element is controlled by optical signals 55 and 56 transmitted from control circuit (3) to the circuit (2) containing the element, which signals are in the form of rectangular pulses synchronised with the source a.c., starting at a zero of the source voltage, and of duration representative of the desired average motor voltage as obtained via feedback from tachometer 5. The element is thus rendered conductive from the start of each alternation and for a period less than the period of alternation. <IMAGE> |
