Current Sharing Dynamics During IGBT ZVS Turn-On in a Hybrid Si IGBT/SiC MOSFET Switch

This article describes the current sharing dynamics of a 1200V Si IGBT/SiC MOSFET hybrid switch for Aircraft Applications. Different switching sequences are utilized to switch the Si IGBT at zero voltage in order to reduce total losses. However, during these switching instants, two effects are usually neglected or are not well taken into account. The first is extra conduction losses during the period where SiC MOSFET conducts all the current to ensure IGBT soft switching. The second one is that the current in the IGBT slowly rises after it turns on due to parasitic inductance between IGBT, SiC MOSFET and diode. The focus of this work is to discuss and precisely model these effects and their impact in hybrid switch losses. A method to measure the dynamic behavior of this hybrid switch and precisely determine associated losses is presented and experimentally verified.