Optimal Design and Control of DC Charging Stations Using CLLC Converter For Grid Integration

The increase in the penetration of renewable energy sources makes the future grid more vulnerable to frequency and voltage fluctuations. Electric vehicle (EV) charging stations can be used as a source of energy to support the grids’ voltage and frequency during load or generation disturbances. However, managing the contribution of each EV in the total energy injected into the grid, considering each EV capacity while maintaining minimal losses, is challenging. This paper presents an algorithm to distribute the total injected energy among the EVs based on their state of charge, which determines the optimal power injected by each EV inside the parking lot. Furthermore, the design procedure of the CLLC converter for the EV charging stations is elaborated to meet the requirements of each converter and DC charging station for grid integration. The control of the CLLC converter for both grid-to-vehicle (G2V) and vehicle-to-grid (V2G) conditions is described. The simulation results for different scenarios for EV arrival and departure show the effectiveness of the proposed algorithm in minimizing the loss according to the SOC.