Conversion System for Grid-to-Vehicle and Vehicle-to-Grid Applications

The increasing use of electrical vehicles aroused the problem of batteries charging and the consequent interface with the power grid. Commercial charging solutions are mostly based on unidirectional power flow converters; however, bidirectional power flow converters are an interesting solution when considering smart microgrid applications, with benefits in efficient energy use. In this context, the paper presents a bidirectional power flow converter for grid-to-vehicle (G2V) or vehicle-to-grid (V2G) applications. The conversion system is based on a three-phase voltage source inverter (VSI), which assures the grid connection with a unitary power factor. The direct current (DC) bus of the voltage source inverter is connected to a DC/DC converter that controls the battery power flow. This conversion system can operate in G2V mode when charging the battery or in V2G mode when working as an energy storage system and the power flow is from the battery to the power grid. The conversion system model is presented as well as the control strategy proposed. Simulation and experimental results showing voltages and currents in the circuit are also presented.