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

Abstract

Available capacity of lithium-ion batteries is directly linked to the mileage of the electric vehicle. The cell imbalance is recognized as a significant concern hindering the full utilization of pack capacity. Following the emerging concept of battery reconfiguration, this article proposes a dual-scale hierarchical equalization scheme enabled by a novel four-switch reconfigurable topology. In particular, a four-switch reconfigurable topology is proposed, for the first time, which enjoys the benefits of flexible reconfigurability, moderate complexity, and high fault tolerance. Relying on the new topology, a hierarchical equalization strategy is proposed incorporating the intramodule time-sharing intervention and inter-module splitting recombination. This endeavor contributes to achieving 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%.