A testing method for evaluating shoot-through immunity of IGBTs in an inverter

Abstract

The shoot-through fault in inverters results from a gate noise voltage of power semiconductor switches including IGBTs. Testing the gate voltage under the high-speed switching event is important to evaluate immunity to the fault as well as to analyze the mechanism of the fault. This paper presents a testing method of shoot-through immunity in a PWM inverter consisting of IGBTs because the conventional double-pulse test can miss the shoot-through fault in the inverter. Theoretical analysis reveals that the N-base charge has influence on the gate-emitter voltage in the IGBT, which disturbs evaluating the shoot-through immunity in the inverter. This implies that IGBTs have a different characteristic from MOSFETs when the double-pulse test is carried out. The testing method introduces an additional pulse into the off-state IGBT to release the N-base charge, the circuit operation of which is the same as the inverter. Experimental results confirmed that the method did not affected by the N-base voltage, so that it is applicable to testing the shoot-through immunity of IGBTs in an inverter.