Performance Evaluation of SiC MOSFET Hybrid Switches with Reverse Conducting IGBTs

Hybrid Switches (HS) are an excellent way of reducing cost without sacrificing performance by combining the switching performance of SiC MOSFETs with the conduction performance of Si IGBTs. However, given that the SiC MOSFET usually has a smaller current rating, the third quadrant performance needs to be investigated especially if SiC Schottky Barrier Diodes (SBDs) are avoided to limit cost. Hence, the performance of HS is compared for three different technologies, namely, (i) SiC MOSFET in with a Reverse-Conducting silicon IGBT (HS-A) (ii) a SiC MOSFET with a silicon IGBT (HS-B) and (iii) a SiC MOSFET with Si IGBT co-packaged with a SiC SBD (HS-C). First and third quadrant static and dynamic characteristics have been measured at different temperatures and different currents. The results are used as inputs into motor drive electrothermal simulations where the losses and efficiencies of traction inverters are assessed for the three HS technologies at 2 kHz and 10 kHz switching frequencies. The simulation results show HS-A has comparable performance with HS-C at 2 kHz and 16% lower losses than HS-B. At 10 kHz, HS-A has 10% higher total loss than HS-B and 30% than HS-C. The results show that using Reverse Conducting IGBT (RC-IGBTs) can give a good compromise between cost and performance in applications where third quadrant operation is critical.