基于荷电状态的锂离子电池组有源双向均衡器及其功率分配控制策略

Abstract Promotion green energy has driven the development of energy storage systems (ESS) and electric vehicles (EVs), both of which can significantly reduce environmental pollution. However, the use of multiple battery cells within a battery pack can lead to imbalances, resulting in uneven capacity or voltage among the cells. To mitigate this issue, battery balancers are necessary to maintain equilibrium among the cells in a battery pack. This paper presents the development of four sets of bidirectional buck-boost DC-DC converters that activate a balancing mechanism when the capacity difference exceeds a certain threshold. The balancing mechanism is based on the state of charge (SOC), ensuring that load power is effectively distributed during discharge and that charging current is distributed during charging. The proposed technique saved 25.78 % of time in different output voltage range scenarios, increasing to 32.5 % with the improved control method. In the charging mode, the proposed method saved 17.03 % of time in different balancing coefficient scenarios, increasing to 26.41 % with the adjustment of the duty cycle variation range. The results confirmed that balancing could be maintained even when one battery reached 4.2 V, and the capacity difference at the end of charging was less than 1 %. The proposed technique achieved a time savings of 25.78 % across various output voltage range scenarios, which increased to 32.5 % with the enhanced control method. In charging mode, the proposed method resulted in a time savings of 17.03 % across different balancing coefficient scenarios, which improved to 26.41 % with adjustments to the duty cycle variation range. The results confirmed that balance could be maintained even when one battery reached 4.2 V, with the capacity difference at the end of charging being less than 1 %.