Fuzzy controlled energy converter equalizer for lithium ion battery packs

Balancing algorithms are based on extracting or adding charge in order to have balanced cells. Their goal is to protect the battery from damage and to help prolong the battery´s life. Without a balancing system the total capacity of the pack will decrease more rapidly, and the estimation of the state of charge will be unreal. The paper presents a fuzzy controlled battery equalization method for series connected battery strings. The algorithm was developed in order to reduce the cell equalization time. The simulation and experimental results show the advantage of the predicted equalization algorithm for lithium-ion battery stacks.