SiC MOSFET Hybrid Switches with Reverse Conducting IGBTs: Loss and Surge Current Analysis

Hybrid Switches (HS) reduce cost without sacrificing performance by combining the switching performance of SiC
MOSFETs with the conduction performance of Si-IGBTs. However, given the smaller current rating of the SiC MOSFET, the loss performance and third quadrant surge current robustness needs to be investigated especially if SiC Schottky Barrier Diodes (SBDs) are avoided. These parameters have been analyzed for three different hybrid-switches, namely, (a) SiC MOSFET with a Reverse-Conducting silicon IGBT (HS-A) (b) a SiC MOSFET with a silicon IGBT (HS-B) and (c) a SiC MOSFET with Si IGBT copackaged with a SiC SBD (HS-C). First and third quadrant static
and dynamic characteristics have been measured at different temperatures and currents. The third quadrant surge current robustness has also been measured by taking the devices to their electrothermal limits. Loss analysis results show that HS-A outperforms HS-B and is competitive with HS-C at low switching frequencies. HS-A has 16% higher maximum surge energy than HS-B while HS-C exhibits the best performance due to its dedicated diode. The results show that using RC-IGBTs can give a good compromise between cost and performance in hybrid switch
applications where third quadrant operation is critical.