| 摘要 |
A switching circuit for a switched reluctance motor or generator comprises positive and negative power lines 10/12, a string of smoothing capacitors 14 serially connected between them and two pairs of gate turn-off thyristors 22, 24/30, 32 connected to either end of a phase winding 18 of the motor or generator. Circulating diodes 26/34 are connected between the ends of the winding and the opposite power line and further circulating diodes 36/38 are connected between each pair of thyristors. A mid-point 16 between the capacitors is connected between the further diodes. At switch-off one of the outer GTO's is first opened so that one of the diodes conducts and current in the winding is routed via the mid-point. Then the other outer GTO is opened so that current now circulates through both of the diodes and substantially no voltage is dropped across the winding. The first inner GTO is then opened causing one of the diodes 26/34 to conduct. Thereafter the second inner GTO can be opened. Turn-on requires a progressive reversal of the turn-off sequence if winding current continues to flow. Otherwise, all but one outer GTO are turned on together followed by the omitted GTO after a delay. The GTO to be omitted initially at turn-on is chosen to provide the desired correction to the voltage at the midpoint. <IMAGE> |
