| 摘要 |
PURPOSE:To reduce remarkably a turn-on and turn-off loss, i.e., switching loss simply by adding a short-circuit switch and its control circuit. CONSTITUTION:The semiconductor switch 14 short-circuiting base and emitter of a power transistor (TR) 1 and a driving circuit 15 driving the base of the switch 14 are added. In case of turning-on, since the switch 14 is prevented from being turned off during a period T until a current iL of a reactor 6 rises sufficiently even if an output e8 of a photocoupler 8 is turned on in this drive circuit 15, a base current iB rises rapidly when the switch 14 is turned off. Thus, the turn-off loss is reduced sufficiently. Further, in case of turning-off in the circuit 15 similarly, the switch 14 is turned on at the same time when an OFF- command is given. As a result, since the base and emitter of the TR1 are short- circuited, the turn-off time is quickened, resulting in quickening sufficiently the leading of an ON-voltage VCE, thereby reducing considerably the turn-off loss. |
