Multi Active Bridge converter with DPS modulation for bidirectional EV charging from DC traction grid

The lack of developed, accessible public electric vehicle (EV) charging infrastructure significantly limits EV development in urban areas, creating a need for cost-effective solutions that allow charging a significant number of EVs. One of the promising solutions to reduce charging station installation costs is its connection to existing infrastructure and usage of multi-terminal charging stations based on a multiport converter, which decreases the number of components needed compared to an independent connection, where each appliance has its own converter. Nevertheless, existing multiport solutions either lack ports scalability, having only several independent ports with no extension ability, or do not allow independent operation of the ports, introducing significant complexities in the control system due to ports interaction. To overcome the aforementioned issues, this paper studies a multiport current-fed multiple active bridge (CF-MAB) converter connected to a low-voltage DC traction network that integrates N EV chargers and a battery energy storage (BES), using only 6N switches, whereas independent appliances connection requires 8N+6 switches (a 3-phase interleaved boost for BES and N DAB converters for each EV). Importantly, the isolated ports of the proposed MAB converter operate independently and are controlled individually. Simulation and theoretical analysis of the converter for a DC grid input voltage of 400-800V, battery port voltage of 1000-1400V and vehicle ports of 3x50 kW, 288400V, revealed an average 5.7% reduction in RMS transformer currents using DPS modulation as opposed to SPS modulation under voltage mismatch ratios across EVs and BES ranging from 0.7 to 1.4.