Loss Modeling and Testing of 800-V DC Bus IGBT and SiC Traction Inverter Modules

This article investigates efficiency gains achieved using an 800-V dc bus and wide bandgap silicon carbide (SiC) semiconductors for a light-duty electric vehicle (EV), rather than an insulated-gate bipolar transistor (IGBT) inverter with a 400-V bus as is commonly used for EVs. Analytical inverter loss models with 600- and 1200-V IGBTs, and 1200-V hybrid SiC and 1200-V All-SiC semiconductors are incorporated into a Chevrolet Bolt EV model and simulated over standard drive cycles. Battery pack voltage variations throughout the drive cycles, as well as variations in junction temperature, resulted in a 16%–27% increased loss compared to fixed voltage and temperature assumptions. To validate the models, experimental testing was performed on a 1200-V IGBT inverter and a 1200-V SiC inverter both powering 160+-kW rated traction machines. The experimentally measured loss was typically within 100 W of the model, demonstrating its accuracy. Going from a 400- to 800-V dc bus with IGBTs, the EV range was modeled to increase 1.2%, while an 800-V bus and all-SiC inverter result in a range increase of 5.0%. An empirical loss model fit to measured inverter data shows the analytical model estimates range within 6 km.