| 摘要 |
PURPOSE:To inhibit the increase of the switching loss of a main circuit transistor by detecting the collector currents of the main circuit transistor and varying a reverse bias at a time when the main circuit transistor is turned OFF and brought to an OFF state by the detection output. CONSTITUTION:The collector currents of a main circuit transistor 3 for a transistor inverter are detected by a collector current detection circuit 26. A power conversion circuit 27 for a reverse bias contains a power supply for the reverse bias reverse-biassing a section between a base and an emitter in the main circuit transistor 3 when the main circuit transistor 3 is turned OFF and brought to an OFF state. Supply voltage for the reverse bias is fluctuated by a signal from the collector current detection circuit 26.
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