Mission Profile Analysis of a SiC Hybrid Module for Automotive Traction Inverters and its Experimental Power-loss Validation with Electrical and Calorimetric Methods

Abstract

This paper investigates the efficiency benefits of replacing the Silicon diodes of a commercial IGBT module for the main inverter application of an electric vehicle with Silicon Carbide diodes, leaving the package, operating conditions and the system unchanged. This ensures that the comparison is directly between the chip technologies without any scope for discrepancies arising out of differences in the packaging, gatedriver circuit etc. A behavioral power loss calculation model is used to investigate the performance of the two modules for various drive cycles (Artemis, WLTP, NEDC). The behavioral power loss model is experimentally validated using two independent measurement methods, namely, power analyser based electrical input output method, and a calorimetric method which was developed especially for the low lossy light load condition. Furthermore, it is shown that the electrical method has close to 30% inaccuracy making it unsuitable for the main inverter applications, especially for comparing two different chip technologies, e.g., Silicon versus Silicon Carbide. The developed calorimetric method in contrast offers lower than 3% uncertainty.