Fast Charging Station for Electric Vehicles Based on DC Microgrid

Abstract

Increasing numbers of electric vehicles (EVs) have led to an increased power demand from the grid. The fast-charging station requires very high power for charging the EVs in a short time (30mins). The rapid high-power (80-240kW) demand results in voltage instability in the power grid. It is important to reduce the impact on the grid due to fast charging of EVs. The effect on the grid due to EVs fast charging is included in this paper. The grid instability is visible during the fast-charging period of the battery. As a solution, a renewable energy source integrated DC microgrid using a multi-step constant current fast charging method is proposed to reduce the effect on the grid. Additionally, the proposed system provides solar PV and/or vehicle to grid power transfer during the no charging/the peak demand period of the grid. The simulation and analysis of the proposed system using the coulomb counting based state of charge estimation method is implemented to show the grid impact and reduction using DC microgrid. A hardware prototype is developed to validate the proposed fast charging method and also to reduce grid impact during the fast-charging operation.