A Review of Battery Cell Equalization Techniques for Use in Real World Applications

Abstract

Abstract: The usable energy available from a lithium-based battery energy storage system is affected by factors both internal and external. One of the most influential and potentially dangerous factors is cell charge deviation. This issue is directly addressable with the use of a battery management system and even more through the use of a cell equalization subsystem. There is a wide variety of cell equalization methods that can be used in low, medium, or high-power applications ranging from residential energy backup systems to electric vehicles and industrial load-shifting grid-tied systems. This paper presents a variety of cell equalization methods and compares each of the distinct cell equalization topologies by evaluating different criteria such as equalization rate, power capabilities, complexity and cost. The result of this comparative study is summarized in a set of comprehensive tables that can serve as a guideline to engineers in selecting the best solution for an application. The use of these comparative tables is also illustrated by looking at different real-world case studies.