Series‐connected battery equalization system: A systematic review on variables, topologies, and modular methods.

Summary: Series‐connected lithium battery packs are widely adopted in industries such as electrical vehicles and large‐scale energy storage systems. It is necessary to configure an equalization system for them to reduce the inconsistency of single cells, to ensure the battery pack cycle capacity. Although many novel active converters have been proposed for equalization, there still lacks systematic analyses on variables, topologies, and modular methods. Therefore, this paper provides a systematic review on the above aspects. Initially, an overall summary is present on current variables for equalization control. Second, the dominant structures are divided into cell‐to‐cell, cell‐to‐pack, and pack‐to‐pack topologies, and their characteristics are pointed out for comparison. And then, the modular methods, including single‐layer‐based, multi‐layer‐based, and hybrid integrations are evaluated via graph theory. Some key issues and potential research directions are given, which are expected to offer assistance on the selection of appropriate variables and topologies for equalization systems in the future. [ABSTRACT FROM AUTHOR]