Failure dynamics of the IGBT during turn-off for unclamped inductive loading conditions

The internal failure dynamics of the insulated gate bipolar transistor (IGB T) for unclamped inductive switching (UIS) conditions are studied using sim ulations and measurements. The UIS measurements are made using a unique, au tomated nondestructive reverse-bias safe operation area test system. Simula tions are performed with an advanced IGBT circuit simulator model for UIS c onditions to predict the mechanisms and conditions for failure. It is shown that the conditions for UIS failure and the shape of the anode voltage ava lanche-sustaining waveforms during turn-off vary with the IGBT temperature, and turn-off current level. Evidence of single- and multiple-filament form ation is presented and supported with both measurements and simulations.