Current Sharing Behavior in Si IGBT and SiC MOSFET Cross-Switch Hybrid

Abstract

The cross hybrid (XS) concept has been demonstrated experimentally with 3.3-kV Si Insulated Gate Bipolar Transistor (IGBTs) and SiC MOSFETs in parallel, and used to calibrate 2D Technology Computer Aided Design simulations. The XS hybrid offers lower switching losses compared with full Si IGBTs and reduced oscillations compared with full SiC MOSFETs. The current sharing mechanism between the IGBT and the MOSFET in the XS hybrid has been elucidated, showing that under typical switching conditions, the IGBT dissipate 98% of the XS hybrid turn-OFF losses compared with the SiC MOSFET. Since the current density of the IGBT in the XS hybrid is twice of that of the full IGBT solution, it exhibits higher dynamic avalanche. These features results in stress at device and package level, thereby compromising robustness and reliability. In order to overcome such issues, we show that increasing the turn-OFF gate resistance improves current sharing in the XS hybrid by delaying the turn-OFF of the MOSFET, and thereby suppressing dynamic avalanche in the IGBT.