| 摘要 |
PURPOSE:To eliminate the need for a special drive power supply by supplying a drive power of the 1st semiconductor device from a main circuit and a discharge current at the turn-off of itself. CONSTITUTION:A capacitor 24 is provided in place a conventional base power supply to drive a BPT 3, the capacitor 24 is charged into a proper voltage from the main circuit power supply 1 via resistors 22, 23 and a base discharge current (commutation current of the main circuit side) when the BPT 3 is turned off is stored via a diode 21 while composite transistors (TR) 3, 4 are in switching operation. When the composite TRs 3, 4 are turned off, the capacitor 24 is charged to a voltage being a dielectric strength of a FET 4 in a path of main circuit power supply 1 main circuit load 2 resistor 22 capacitor 24. The charging voltage of the capacitor 24 is decided by the ratio of resistors 22, 23. |
