On the Feasibility of SiC-based Multiphase Traction Inverters for EV Applications: A Case Study

Employment of Silicon Carbide (SiC) devices and the use of multiphase drives are two emerging trends in electric vehicle (EV) applications. However, technology assessment combining both trends for traction applications has not been thoroughly examined yet. This paper presents a quantitative and qualitative analysis to examine the feasibility of SiC-based multiphase traction inverters. Specifically, voltage source inverters (VSI) and nine switch inverters (NSI) with different phases (five-, six-, and nine-phase) are evaluated in terms of device count, dc-capacitor sizing, efficiency, power density, and cost. The multiphase inverters in the case study are rated at 100 kW considering 400 V and 800 V EV powertrains. Compared to the conventional three-phase VSI, the six-phase VSI was found to have the best feasibility. The latter enjoys reduced dc-capacitor requirements, lower ac cabling cost, and higher fault tolerance capability, while maintaining the same efficiency and power device count.