Experimental Study on a Laboratory DC Fast Recharging Station For Road Full Electric and Hybrid Vehicles

This paper deals with the design criteria, setting up and experimental tests concerning an architecture of DC micro-grid for fast recharging stations of road full electric and hybrid vehicles. The proposed DC fast charging architecture was conceived as the best solution coming from a comparative analysis among well known different architectures, mainly based on AC and DC bus. This analysis evaluated the impact on the main grid, efficiency and charging/discharging power when recharging different kinds of battery packs from real vehicles. Then, a laboratory recharging station was built by means of a 20 kW AC/DC bidirectional grid tie converter interconnected with two different high power DC/DC converters. Through this architecture, the first converter realizes a DC conversion stage at 800 V, whereas the other two converters allow the electric vehicles battery packs to be recharge and a storage buffer to save electric energy when required. Laboratory tests, described in this paper, were mainly devoted to characterize the recharging station in different operative conditions, such as island and vehicle-to-grid (V2G) operation mode, and connecting different types of storage systems to be recharged through the DC fast charging station. The experimental results allowed the identification of energy management and control strategies of each converter and whole recharging station, in order to optimize the energy losses of the power conversion and recharging times, taking into account its interaction with main grid, renewable energy sources, energy storage systems.