Energy and current crowding limits in avalanche operation of IGBTs

The possible different failure modes that limit the maximum avalanche capability during unclamped inductive switching (UIS) in IGBTs is analyzed in this paper. Experimental measurements conducted on different commercial devices show that, at high peak current, the UIS limit moves from energy limitation to current limitation. This current driven failure mode is not well assessed in literature. In this contribution experimental results are provided and discussed with the target of determining experimental fingerprints that highlight different failure modes that affect IGBTs in avalanche operation. Moreover, the electrical waveforms of the UIS experiments are also exploited to provide clear indications on device operation mode.