Multiport DC Fast EV Charger Based on Modular Multilevel Converter and Quad-Active Bridge

This paper presents a multiport DC fast electric vehicle (EV) charger based on a modular multi-level converter (MMC) and a quadruple active bridge (QAB). An adaptive dc link voltage regulator is developed for MMC to reject parameter uncertainties (including change in load). A proportional-integral (PI) based current control scheme is developed to track reference currents for MMC’s unity power factor (UPF) operation. MMC’s sub-module (SM) switching is provided with sorting scheme-based capacitor balancing with level-shifted pulse width modulation (PWM). Three fast charging ports are provided; each can charge an electric vehicle (EV) as a standalone leve1-3 DC charger by QAB converter. Separate control architectures are designed for constant current (CC)/constant voltage (CV) for each charging port of QAB. The simulation is done in Matlab, and the results are shown for a 3.3 kV grid with three identical 200 Ah, 700 V Li-ion batteries with different state-of-charges (SOCs).