In the paper proposed here, we are studying the dynamic avalanche from experimental results first, dynamic avalanche is identified on a punch through insulated gate bipolar transistor (PT-IGBT) module 1200V-300 A from Mitsubishi. Secondly, the phenomenon is analysed thanks to simple solid state devices equations. Numerical simulations are used to confirm experimental results. Simulation results allows us locating the active area of the dynamic avalanche during turn-off under over-current conditions. A PT-IGBT cell is described with MEDICI (TM). a finite element simulator. A mixed-mode simulation is performed thanks to MEDICI (TM) and SPICE (TM). The circuit simulated here is a buck topology with an inductive load. Finally, a thermal analysis is performed to estimate temperature increase due to dynamic avalanche. (C) 2009 Elsevier Ltd. All rights reserved.