Fast Balancing Data-Driven Equalization Strategies of Series-Parallel Switched Capacitor Active Balancing Architecture

The cycle life and health of a lithium-ion battery pack are impacted due to the cell imbalance, thereby constraining the optimum performance of the application. The charge equalization circuit (CEC) is an integrated unit of the battery management system responsible for equalizing the imbalanced cells. The switched capacitor (SC) CECs are a cost-effective active charge equalization solution that offers high power density and control simplicity compared to other CECs. The series-parallel switch capacitor (SPSC) topology is developed to improve voltage balancing by allowing parallel charge transfer operations among series cells. Due to the conventional switching algorithm, the equalization operation in SPSC necessitates the participation of each series cell until the balanced state is achieved. The energy loss resulting from the equalization process is increased as a result of the operation of multiple switches. This paper proposes three equalization algorithms for SRSP topology that have successfully achieved independent balancing control of each cell and optimized utilization of each switched capacitor to minimize operational loss. For validation, simulation and modeling are carried out in the PLECS environment using 14 series cells, where a 9% improvement in equalization time is recorded using proposed switching operation during equalization.