Design of a full SiC voltage source inverter for electric vehicle applications

Taking into account typical power and temperature requirements of electric vehicle applications, silicon carbide based semiconductor devices seem to be the most promising candidates for future high power density traction inverter applications. Therefore, the design of a three-phase DC-AC inverter based on SiC MOSFETs under automotive constraints is discussed in this paper. In order to fully utilize the performance offered by these superior power semiconductors, the electrical design of a high power module in combination with a low inductance DC-link design is presented. The switching behavior of this prototype module is presented, emphasizing the significant improvements SiC power devices offer in terms of performance over state-of-the art silicon IGBTs. For EV applications, the obtained low switching losses in combination with the purely Ohmic output characteristics of these devices result in substantial efficiency improvements which are determined by means of drive cycle simulations. First test bench measurements are presented with the full SiC inverter operating at a switching frequency of 40 kHz. Overall, SiC MOSFETs offer the possibility to significantly increase the performance, power density and efficiency of the electric drive system.