Modular balancing strategy for lithium battery pack based on adaptive fuzzy logic control and energy path optimization

Battery balancing is crucial to potentiate the capacity and lifecycle of battery packs. This paper proposes a balancing scheme for lithium battery packs based on a ring layered topology. Firstly, a two-layer balanced topology based on a Buck–Boost circuit is proposed. Then, an adaptive fuzzy logic controller (AFLC) is adopted to adjust the balancing current between cells, and an ant colony optimization (ACO) algorithm is used to optimize the energy transfer path between battery groups. Simulation results illustrate the effectiveness of the balancing approach. Compared with the centralized and string hierarchical topologies, the new scheme can reduce the balancing time by 48.8% and 30.2%, respectively, and the number of cells in each battery group has little impact on the balancing speed. Compared with the fuzzy logic control (FLC) algorithm under static, constant current charge, and constant current discharge conditions, the AFLC can reduce balancing time by 29.5%, 36.7% and 30.1%, respectively, while increasing energy utilization rate by 11.6%. The ACO-based optimization of the energy path can increase energy utilization rate by 15% and mitigate inconsistency between batteries, at the cost of a small increase in the balancing time. The ring hierarchical topology approach is scalable and hardware costs are reduced. •Two-layer balancing topology based on Buck–Boost circuit is proposed.•Adaptive fuzzy logic controller adjusts the balancing current between cells.•Ant colony algorithm optimizes the energy transfer path between battery groups.•A new index is proposed to quantify energy utilization.•New scheme is compared with balancing alternatives for lithium battery pack.