| 摘要 |
PROBLEM TO BE SOLVED: To protect the resistor of an off-gate circuit, etc., from burning when the gate and emitter of a voltage control type semiconductor device such as an IGBT(insulated gate bipolar transistor) are short-circuited. SOLUTION: A switch 6a, a resistor 6b and a resistor 7a are provided in an off-gate circuit 7. A short-circuit between the gate and emitter of an IGBT 1 is detected by a rectifying circuit 9, a filter 10 and a low voltage detection circuit 11 and a switch 5a and the switch 6a are opened to replace the resistor 6b in the off-gate circuit 7 with the resistor 7a whose resistance value is much larger than the resistance value of the resistor 6b to suppress a gate current to a very little value. |
