| CPC H02M 1/08 (2013.01) [H02M 1/32 (2013.01)] | 16 Claims |
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1. A semiconductor driving device for performing ON/OFF control of a semiconductor switching element by applying gate voltage, the semiconductor driving device comprising:
a control circuitry which generates an ON/OFF command for the semiconductor switching element;
a gate power supply circuitry which generates voltage to be applied between a gate terminal of the semiconductor switching element and a reference terminal serving as a reference for the gate voltage;
a gate driving circuitry which has a first transistor of a first type directly connected to a positive potential of the gate power supply circuitry and a second transistor of a second type that is different from the first type directly connected to a negative potential of the gate power supply circuitry, and applies the voltage generated by the gate power supply circuitry, between the gate terminal and the reference terminal; and
a gate leakage current detection circuitry which detects gate leakage current of the semiconductor switching element on the basis of voltage occurring between both terminals of a circuit having a gate resistor which limits current for charging a gate of the semiconductor switching element and the first transistor, or a circuit having the gate resistor and the second transistor, using a negative-side potential or a positive-side potential of the gate power supply circuitry as a reference,
wherein the control circuitry diagnoses deterioration in gate withstand voltage of the semiconductor switching element on the basis of a value of the gate leakage current detected by the gate leakage current detection circuitry in a period in which a gate potential of the semiconductor switching element is fixed at the potential used as the reference by the gate leakage current detection circuitry, of the positive-side potential or the negative-side potential, during switching operation in which the semiconductor switching element repeats ON/OFF operation.
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