Reconfigurable multiport solid-state transformer for DC fast charging stations

Abstract

This thesis presents a Solid-State Transformer (SST)-based Electric Vehicle (EV) fast charging station that enhances reliability and optimizes power distribution. Traditional SST-based stations rely on a shared DC bus, susceptible to faults that disrupt the entire system. The proposed system introduces multiple independent DC buses, isolating faults and improving reliability while eliminating the need for additional DC-DC converters, reducing costs and space. Reconfigurable ports deliver 800V, 400V, and 200V, accommodating heavy, medium, and light EVs. A dynamic reconfiguration algorithm adjusts the ports based on vehicle requirements. MATLAB/Simulink simulations confirm stable charging currents and voltages under varying loads. A scaled-down prototype achieves an efficiency of 93.75%, with experimental results showing light EVs charged at 1.25A/50V and heavy EVs at 2.5A/100V, with an 8.2% voltage ripple. Grid current THD remains below 5%, meeting IEEE 519-2022 standards. The system enhances EV fast charging stations' reliability, efficiency, and cost-effectiveness.