Control Design for Effective Usage of Electric Vehicles in V2G-Enabled DC Charging Stations

This article discusses the usage of electric vehicles (EVs) to enable vehicle-to-grid (V2G) in DC charging stations. The V2G-enabled DC charging station is equipped with bidirectional DC/DC converters for both DC chargers and the energy storage system (ESS) and a three-phase two-level AC/DC voltage source converter for connecting to the low-voltage grid. A proposed controller with a state-of-charge (SoC) balancing algorithm for a bidirectional DC charging station is designed to offer the capability to limit the injected power from the grid using both EVs in V2G mode (V2G-EV) and the ESS. It ensures the safety of each V2G-EV battery by communicating with the EV battery management system (BMS) and receiving its SoCs, charge/discharge current limits, and energy capacity. Finally, it aggregates EV batteries and the optional ESS using the proposed SoC balancing algorithm. Several cases are developed to evaluate the performance of the proposed control design in the studied DC charging station model. The results validate the performance of the control design in both offline simulation and controller-hardware-in-loop (C-HIL) implementation via a digital signal controller (DSC) and a real-time simulator.