| 摘要 |
PROBLEM TO BE SOLVED: To continuously heat by feeble input under the condition that a switching loss can be reduced. SOLUTION: A turn-on delay part 41c refers terminal voltage VCS of a snubber capacitor 15, and it extends turn-on delay time TD1' as TD1'=TD1+ TDX, when the terminal voltage VCS does not get to the direct-current power- supply voltage by reduction of the input setting value if the turn-on delay time remains at a fixed value TD1. Then, charging time of the snubber capacitor 15 is extended and the terminal voltage VCS is increased, thereby potential difference impressed between a collector and an emitter is reduced when IGBT 6 is turned on next time, thus a switching loss is reduced. |
