Bidirectional full-bridge converter based SOC equalization system design for series-connected battery string

The operation environment and manufacturing process cause the problem of charge imbalance for battery pack. In order to solve the problem, a bidirectional equalization strategy using centralized structureis was proposed. The bidirectional energy transfer was implemented by a bidirectional full-bridge converter. Close loop control makes equalization current constant. The cell SOCs were estimated by using the Open Circuit Voltage(OCV) charging and discharging curves considering the hysteresis effect. Experiments were taken to evaluate the performance. The equalization current is 3A, which satisfies the requirement of equalization for battery pack. ©, 2015, Editorial Department of Electric Machines and Control. All right reserved.