Current imbalance analysis and magnetic-based consistency evaluation of Lithium-ion parallel-connected battery modules

The performance and safety of lithium-ion parallel-connected battery modules (PBMs) are critically limited by cell-to-cell variations. To address the persistent challenges in understanding dynamic current imbalance mechanisms and developing practical consistency evaluation methods, in this study, a second-order equivalent circuit model (ECM)-based discrete current modeling method is developed to systematically reveal the impacts of cell parameter variations and OCV-SOC nonlinearity on branch current imbalance. Building upon the branch current imbalance analysis, two novel current-driven consistency evaluation indicators are constructed. Furthermore, a magnetic flux density-based method enables non-invasive current reconstruction, synergizing with the proposed indicators to evaluate module-level and cell-pair inconsistencies. Experimental validation confirms the efficacy of the proposed method in simulating PBM electrical behaviors, elucidating current imbalance patterns, and quantifying consistency levels. Those findings provide actionable guidelines for optimizing PBM design and evaluating in-service module performance.