Improved Short-Circuit Type II Behavior of a 1.7 kV Si-SiC Hybrid Switch

The short-circuit robustness of a Si-SiC hybrid switch depends on the driving concept. A Si-SiC hybrid switch consists of a Si IGBT and a SiC MOSFET connected in parallel. If both switches are driven separately, both the Si IGBT and the SiC MOSFET have to be short-circuit robust. The short-circuit withstand time of the hybrid switch is then defined by the least robust device. In general, SiC MOSFETs have a lower short-circuit withstand time than Si IGBT. A gate drive circuit is proposed that limits the short-circuit current to the Si IGBT, thereby improving the short-circuit robustness of the hybrid switch. A SiC MOSFET without short-circuit robustness can be used. An on-state short-circuit (short-circuit type II) of a hybrid switch with separate gate drivers and with the newly proposed gate driver is experimentally investigated, analysed and compared.