Efficient Bidirectional Charger Design For Power Grid V2G

Abstract

With the large-scale promotion of electric vehicles, research on their charging modules has always been a hot topic, and the development of V2G technology will bring a tremendous transformation to the current grid operation. The traditional charger is AC input, using a rectifier and a unidirectional DC/DC converter to achieve the charging function, and can only provide a one-way charging function. At present, the construction trend of the charging station is the common DC bus, connecting the DC/DC converter as a charger. In this paper, a high-efficiency bidirectional charger topology for common DC bus charging stations is designed. The converter operates in both constant current and constant voltage modes. The energy can flow in both directions and can respond well to the demand of the power grid V2G. Compared with conventional isolated bidirectional converter topologies such as DAB, LLC, etc., this topology does not have reactive current flow, high efficiency, and a wide range of output voltage. It is possible to configure the inductor current as a control object to form a double-loop control with better dynamic characteristics. At the same time, Easily control the distribution of the power of the common DC bus in parallel. An optimized solution for setting the LCD absorption circuit is proposed. The loss and system efficiency of the DC/DC converter are analyzed. Finally, the feasibility is verified by simulation and experiment.