Hybrid charging strategy with adaptive current control of lithium-ion battery for electric vehicles

Abstract

Abstract The synergy of electric vehicles (EVs) and renewable energy (RE) can improve the energy consumption, and participate in grid regulation by vehicle-to-grid (V2G) technology. In this paper, a hybrid charging strategy with adaptive current control for EVs is proposed in this synergistic process. First, the battery parameters are tested by the hybrid pulse power characteristic. Then, the equivalent circuit model is established and the charging characteristics are obtained. Second, inspired by the multi-stage constant current (MS-CC) method, a constant current-constant current-constant voltage (CC-CC-CV) charging strategy is proposed to moderate the temperature of the battery by suddenly dropping the charging rate in the second constant current stage. Third, for the first constant current stage, the adaptive current profile is utilized based on the variable internal resistance of the battery, which can effectively reduce the ohmic losses during the charging process. The comparative experiments show that the CC-CC-CV strategy can alleviate the maximum temperature of the battery. Without harming the charging time and capacity, the hybrid charging strategy can effectively reduce the ohmic losses by 1.2%. Moreover, these advantages are more significant as the charging current increases. Finally, the application of the proposed charging strategy in the smart building with RE is discussed.