Comparative Evaluation of SiC/GaN/Si-based Drive-train Inverters for Light Electric-Vehicles

Despite projected growth in light electric-vehicle (lEV) segment, the innovation in lEV drive-train is limited due to economic-constraints. In this paper, wide-bandgap (WBG) SiC/GaN based drive-train inverter designs for next-generation lEVs are evaluated in comparison with conventional Si-based inverter solutions. The analysis is executed by considering the commonly used six-switch inverter topology, space-vector-pulse-width-modulation (SVPWM), accurate power loss and volume models and cost estimates. Detailed simulations are carried out for 10 kVA inverter designs at 72 V, 150 V and 300 V DC-link voltages, while utilizing the manufacturer’s thermal models for WBG and Si-based devices. A comparative evaluation reveals that WBG-based drive-inverter designs for lEVs can provide considerable improvements in efficiency and power-density with a slight increase in cost compared to Si-based drive-inverter designs. Additionally, an increase in the DC-link voltage can enhance the efficiency and power-density (depending on the continuous power requirement), provided sufficient current is available for motor torque development. A SiC-based 10 kVA drive-train inverter prototype is fabricated, which operates at 300 V DC-link voltage and demonstrates an efficiency of 98.75%, power-density of >40 kVA/L and has a cost price of USD 485, which are quite close to the respective simulation/theoretical model based estimates. An GaN-based 10 kVA drive-train inverter prototype operating at 150 V DC-link voltage is also fabricated (at~USD 400) that is capable of 98.9% efficiency and >45 kVA/L power-density.