Novel Reconfigurable Topology-Enabled Hierarchical Equalization of Lithium-Ion Battery for Maximum Capacity Utilization

Available capacity of lithium-ion battery is directly linked to the mileage of electric vehicle. The cell imbalance is recognized as a major concern hindering the full utilization of pack capacity. Following the emerging concept of battery reconfiguration, this paper proposes a dual-scale hierarchical equalization scheme enabled by a novel 4-switch reconfigurable topology. In particular, a 4-switch reconfigurable topology is proposed, for the first time, which enjoys benefits of flexible reconfigurability, moderate complexity, and high fault tolerance. Relying on the new topology, a hierarchical equalization strategy is proposed incorporating the intra-module time-sharing intervention and inter-module splitting-recombination. This endeavor contributes to achieving the all-cell flexibility, which further promises the all-cell equalization and maximum capacity utilization. Hardware-in-the-loop results validate that the proposed reconfigurable topology-enabled hierarchical equalization strategy can improve the pack capacity utilizing rate by 11.3%.