An Integrated Control Strategy for State of Charge Balancing with Output Voltage Control of a Series Connected Battery Management System

Cell balancing of batteries through state of charge (SOC) is a major requirement for a series connected battery management system (BMS). In this paper, an integrated control algorithm is proposed to equalize the SOC of the battery cells while maintaining a steady DC bus voltage at the output side of the battery system. The control algorithm utilizes the droop concept to achieve the objectives through dc-dc converters which connect the batteries in series. This integrated control strategy provides higher reliability and flexibility compared to the conventional BMS control structures due to its decentralized features without needing any communication among the batteries. Moreover, the configuration can be expanded for high voltage dc applications by connecting additional batteries in series. The proposed control algorithm is developed in a dynamic simulation environment for a three-battery system, and is validated on an equivalent experimental setup.