A Futuristic Silicon-Carbide (SiC)-Based Electric-Vehicle Fast Charging/Discharging (FC/dC) Station

Abstract

Medium-voltage (MV) grid-connected solid-state-transformer (SST) based fast-charging (FC) stations provide several merits in terms of improved efficiency, power density, current limiting capability, etc. In this paper, a MV grid-connected public multi-port FC/dC station is proposed which not only resembles a refuelling station’s functionality by simultaneously interfacing all three PEV categories (heavy or <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">h</i> PEVs, medium or <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">m</i> PEVs and light or <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">l</i> PEVs), but also facilitates bidirectional power flow for V2G applications. The modulation, operational and control schemes of the front-end (FE) MVAC-LVDC single-stage conversion and back-end (BE) DC-DC conversion of the proposed architecture are explained in detail. Hardware-in-loop test results for full-scale 22 kV, 1 MVA architecture’s bidirectional operation verifies the proposed operation and control schemes. The architecture facilitates simultaneous FC/dC of 1 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">h</i> PEV within 49.5 min, 2 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">m</i> PEVs within 28 min and 4 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">l</i> PEVs within 16 min. Finally, a proportionally scaled down 1 kV, 13.2 kVA experimental verification validates the architecture’s performance during drastic net power flow change conditions and exhibits a peak efficiency of 96.4% with a power density of 3.2 kVA/L. A comprehensive benchmarking of the proposed architecture with commercially available FC products is also presented.