Modularized charge equalizer using fuzzy logic controller for Lithium-ion battery system

The battery imbalance which exists in the Lithium-ion battery system of electric vehicles, evidently decreases the total storage capacity and the whole life of batteries. To solve this problem, a modularized battery equalizer is proposed in this paper. Using multiple transformers which have two secondary windings, the modularization of battery equalizer and the energy transfer are achieved. In order to improve the equalization performance, a fuzzy logic controller (FLC) is proposed to regulate the equalization current and the equalization period. Experiment results show that over-equalization is avoided and equalization time is reduced with the FLC.