Practically achievable WLTC loss improvements for the Si/SiC hybrid switch approach in a 400 V automotive traction inverter application – a retrofitting case study

Abstract:
Combining the gold standard conversion efficiency of the SiC MOSFET with the attractive price level from the well-established Si IGBT by using both semiconductor types in a parallel arrangement leads to the so-called Si/SiC hybrid switch. Exploring this approach under automotive constraints, a 400 V traction inverter is retrofitted with a hybrid switch power module showcasing the achievable efficiency improvement compared to an IGBT counterpart already in widespread usage for mass production. Accompanying simulation results and test bench runs demonstrate WLTC loss savings in the range of 34 % on inverter level, translating into a reduction of 13 % of combined inverter and machine losses. The implemented model is described in detail and verified by means of extensive test runs. Performance limitations are discussed which are specific to this retrofitting approach.