Investigation of the electro-thermal stress affecting IGBT modules in high-pulsed power resonant converters

This paper investigates the electro-thermal stress levels and related degradation risk affecting standard technology multichip IGBT modules when used in pulsed power resonant converters. Indeed, these feature fairly unique operational characteristics, which differentiate them substantially from more common power electronics applications (e.g., inverters, dc-dc converters). First, an overview of the converter functioning is provided; then, an a priori minimisation of the electro-thermal stress levels affecting the active switches (IGBTs) is searched for: this is based on an experimental parametric study of the turn-off snubber and of the DC-link capacitance value for which the overall switching power losses can be minimised. Accurate calorimetric measurements of the switching losses and infrared measurements of the IGBTs surface temperature during transient operation are presented. Simulation is used to complement the gained information in the frequency range not covered by the experimental method.