Impacts of using Different Semiconductor Technologies on Drivetrain Optimization

In electric passenger vehicles with modest performance the drivetrain usually consists of one inverter, one electrical machine and a single-speed transmission. The inverter is typically a two-level inverter using either Si IGBT transistors with an anti-parallel Si diode, or a SiC MOSFET transistor with or without an anti-parallel diode. The benefits of selecting SiC MOSFET as semiconductor technology are clear: increased efficiency and better thermal properties. The benefit of Si IGBT is lower cost for the manufacturer. However, a fair comparison must consider drivetrains that have been optimised with the different semiconductors in mind since it is the system level cost and efficiency that is most interesting from a vehicle-level perspective. In this paper, the production and running cost of drivetrains using Si IGBT and SiC MOSFET are compared. Furthermore, the paper includes a cost model for traction inverters that has been developed in collaboration with a large industrial partner in the automotive industry.