| 摘要 |
PURPOSE:To always decrease and interrupt and over-current and to prevent the element destruction by taking priority to the fact that a gate voltage is lowered to a prescribed value more than the stopping signal at a control side after the over-current is detected. CONSTITUTION:The gate and collector of a static induced type self-arc extinction element IGBT 10 are connected through a resistance 11 and a diode 12 and the connecting point of the resistance 11 and the diode 12 is connected to the base of a transistor 15. An equivalent overcurrent detecting circuit to detect the collector voltage during the gate voltage impression is constituted at an IGBT 10. An overcurrent detecting signal is transferred to a control side by the transistor 15, the resistance 17, a diode 18 and a capacitor 19 and a gate voltage adjusting circuit is constituted. To the emitter of the transistor 15, a resistance 20 and a capacitor 21 are connected, one side of the capacitor 21 is connected to the base of a transistor 23, the collector of a transistor 23 is the collector of a transistor 3 and an ON holding circuit is constituted. Thus, when the overcurrent is detected, after the flow is surely decreased, the interruption can be performed. |
