Edge termination impact on clamped inductive turn-off failure in high-voltage IGBTs under overcurrent conditions

This work provides a physical insight into the failure of high-voltage IGBT modules for railway traction when an overload current event occurs during a clamped inductive turn-off. The inspection of failed IGBTs in power modules coming from the field reveals burnt-out points in the vicinity of the device edge termination. This physical signature has been also verified by experimental tests. To explore this result, physical TCAD simulations have been carried out considering, for the first time, the electro-thermal mismatch introduced by the edge termination. From simulation and experimental results, a destructive dynamic avalanche phenomenon at the last IGBT cell is identified as responsible for the observed failure.