| 摘要 |
PURPOSE:To increase the controllable current and to reduce power consumption and device cost by closing only for a short time the 1st and 2nd switching elements just before the seminconductor element is turned off so as to utilize the energy stored in a capacitor thereby assisting the off-operation of the semiconductor element. CONSTITUTION:When a GTO1 is turned off, a capacitor 4 is charged through diodes 2, 6. Then an ON-signal 51 is given to transistors (TRs) 8, 9 by a base current control circuit 11 at the time t2 to turn on the TRs, then the charge stored in the capacitor 4 is discharged in a closed circuit comprising capacitor 4-TR 9-resistor 3-diode 7-TR 8-capacitor 4 and a discharge current 61 flows therethrough. A voltage drop is caused by the discharge current 61 to the diode 7, the resistor 3 and the TRs 8, 9, and the voltage drop of the diode 7 is compar atively large, a reverse voltage is impressed to the GTO1, which is brought into a state turned on easily. |
