| 摘要 |
PURPOSE:To reduce the loss of electric power at the application of reverse bias, by detecting a reverse bias voltage when a transistor (TR) is turned from on to off, and transferring the reverse bias current of the base to a high resistance circuit. CONSTITUTION:A resistor R6 is connected between the base and emitter of a main TRT7. A forward bias current controlling TRT4 supplies a forward bias current from a forward bias power supply E1 to the TRT7. A reverse bias current controlling TRT5 supplies reverse bias current from a reverse bias power supply E2 to the TRT7. If reverse bias voltage VEB generated between the emitter and base of the TRT7 exceeds the voltage of a Zener diode ZD9 when the TRT7 is turned off by reverse bias current iB2, an ignition signal is applied to the gate of a thyristor TH7 to ignite the thyristor TH7, the TRT5 is turned off and the reverse bias current at the TRT7 is reduced and stopped flowing, so that the loss is sharply reduced. |
