| 摘要 |
PROBLEM TO BE SOLVED: To provide a voltage clamping circuit which has the characteristic of a Zener diode used in a power converter or the like and has a high voltage and a large capacity. SOLUTION: A semiconductor switching element (for example, an IGBT insulated gate bipolar transistor TR) 1 and a diode 2 which has the cathode and the anode connected in antiparallel to the collector and the emitter of the semiconductor switching element 1 are provided, and a first resistance R1 (3) is connected between the collector and the gate of the semiconductor switching element 1, and a second resistance R2 (4) is connected between the sate and the emitter. First and second resistances R1 and R2 are so selected that VCE=VGES×[(R1+R2)/R2] is true with respect to relations between a clamp voltage VCE and a threshold VGES of the voltage between the gate and the emitter which switches the cut-off state between the collector and the emitter of the semiconductor switching element 1 to the conduction state.
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