A comprehensive review of balancing circuits for series-connected lithium-ion battery packs

Lithium-ion battery balancing technology serves as a critical approach to addressing the voltage imbalance among individual cells in series-connected battery packs, which results from inconsistencies in internal parameters, materials, and manufacturing processes during long-term operation. First, the paper analyzing the necessity of battery balancing, then categorizes balancing methods into passive and active circuits, providing a detailed comparison of their differences. Active balancing circuits are further classified into four types, with a focus on analyzing their working mechanisms and design methodologies. The advantages and limitations of each balancing scheme are clarified, and their suitable application scenarios are discussed. Finally, based on the evolving requirements for battery balancing circuits, potential future research directions are proposed.