Electric Vehicle Fast Charging Integrated with Hybrid Renewable Sources for V2G and G2V Operation

DC Microgrid (DCMG), fed from renewable energy sources (RESs), is one of the most efficient and cost-effective ways that integrate electric vehicles (EVs) for charging. However, the DCMG, without any storage units, is prone to voltage fluctuations under uncertain weather conditions in addition to EV loads. Thus, the batteries of the EVs connected to DCMG can act as storage units to alleviate voltage fluctuations through their charging/discharging operations. This paper presents an energy management strategy of DCMG utilizing RESs, load, AC grid, and EV batteries to maintain its stability using vehicle-to-grid (V2G) and grid-to-vehicle (G2V) operations through a BDDC converter. Besides, in this work, a bidirectional DC-DC converter (BDDC) control technique is proposed, which contains an additional voltage loop in conjunction with a power loop to minimize the DC bus voltage fluctuations. The proposed approach is evaluated under various operating conditions using a MATLAB/Simulink model of a DCMG system. Further, using a WAVECT (WCU300) control interface, the proposed control has been successfully validated on an experimental test bed. It is observed that the proposed BDDC control stabilizes DC bus voltage under different power conditions while maintaining the power balance in the system.