A novel UIS test system with Crowbar feedback for reduced failure energy in power devices testing

A new unclamped inductive load (UIS) test system is presented, provided with a Crowbar protection that is able to ‘‘sense” the failure of the DUT. Differently from the standard UIS test systems with a Crowbar device, this system turns on the Crowbar only when it is really needed i.e. immediately after the DUT fails during the breakdown transient. This was achieved by feeding back the DUT collector voltage to the test system control electronics. Our measurements performed on commercial power devices show that this improved UIS test system can, in the event of a failure, drastically reduce the energy dissipated on the DUT and hence its related damage effects, giving the possibility of locating the failure starting point with better accuracy and performing subsequent analyses on the damaged devices aimed to infer the failure causes.