An analysis of the power transistors of electric vehicle inverters: present and the future trends

Abstract

The three-phase voltage source inverter is one of the most important components of electric vehicle (EV) drive systems. Nowadays, an interesting transition can be observed in the type of the power switches used in the inverters. Formerly, only silicon-based insulated gate bipolar transistors (Si IGBTs) were used as power switches. Currently, these are increasingly replaced by wide-bandgap-material based power switches, like the silicon-carbide-based (SiC) power transistors and the gallium-nitride-based (GaN) power transistors. These devices make it possible to overcome several limitations of Si IGBTs and to optimize the efficiency of EV drive systems, thus resulting in increased drive cycle efficiency and increased drive range. However, these devices also have some drawbacks compared to Si IGBTs, which make the transition from Si IGBTs to these new devices slower. This paper investigates the different types of power switches that can be used in EV inverters from several aspects. In addition to the technical- and the safety aspects, including lifetime, reliability and the possible modes of failure, other aspects like costs, market needs, and market availability are taken into account as well. A deep study of these aspects is carried out, and based on that, an analysis is made for the expected future trend for the power switches of EV inverters. Conclusions are made based on the detailed analysis.