Experimental evaluation of SiC-based medium voltage Series Resonant Dual-Active-Bridge three-level DC/DC converters for EV charging

Abstract

This paper compares two topologies of SeriesResonant Dual-Active-Bridge (SRDAB) converters with threelevel input applied for EV charging from medium voltage (MV) bipolar DC-link. To convert such a voltage with the utilization of low-voltage silicon carbide (SiC) transistors Active-NeutralPoint-Clamped (ANPC) and series-connected half-bridges(SHB) legs from the DC-link side were examined. Additionally,to increase the efficiency of energy conversion in a wide operating range minimum current trajectory (MCT) control algorithm was applied in each converter. To make a fair comparison between both solutions dedicated laboratory setup was designed and built where ANPC and SHB submodules could be interchanged. Conducted simulation and experimental research confirmed that both configurations could be successfully employed as an isolated DC/DC stage in EV charging systems. The measured peak efficiencies, in either case, were close to 99%, and the performance of both solutions was satisfactory in the entire operating range. However, in applications with a broader input and output voltage range, the SHB leg could be more beneficial.