Evaluation and Efficiency Comparison of Soft-Switching ARCP SiC-Based Traction Inverters in Electric Vehicles

The hard-switching (HS) two-level (2-L) topology with no EMI filters dominates in traction inverters for electric vehicles. Alternatively, by adopting the soft-switching (SS) auxiliary resonant commutated pole (ARCP) topology, switching frequency can be raised and have chance to shrink passive components. However, literature mostly focused on evaluating efficiency of the ARCP for low-current drives or grid-tied inverters, whereas evaluation for high-current traction inverters is missing. To cover this gap, this paper proposes a waveform-based loss model that can easily calculate the additional loss generated by auxiliary circuits in ARCP. The derived model shows accuracy compared to the circuit-level simulations. Combining with chip-area-based model from latest generation SiC MOSFETs, it is discovered that the performance of ARCP is greatly impacted by the device characteristics. With the latest SiC MOSFETs, the efficiency improvement by using SS ARCP to replace HS 2-L is difficult to exceed 0.5 % even at switching frequency of 100 kHz. Capability of shrinking DC-link capacitors is also limited by the large output current. Eventually, from the aspect of efficiency improvement, the HS 2-L is still a promising and low-cost solution for high-current traction inverters.