Integrated fuzzy-based modular cell balancing using mono circuitry for electric vehicle applications

Series-parallel connected Li-ion battery string is an inevitable component of electric/hybrid electric vehicle (EV/HEV). One of the common concerns of battery system is charge imbalance among the series connected batteries, which leads to over voltage/under voltage stress, reduced cycle life and even fire hazard. To overcome these issues, various cell balancing circuits have been developed during the past years, in which most of these circuits have failed to consider state of charge (SOC), the unavoidable parameter in battery balancing. This paper proposes a novel fuzzy-based mono circuitry for balancing cells arranged in module, considering SOC variations of battery. The performance of the proposed method is validated under MATLAB/Simulink environment by considering twelve cells arranged in four modules. Through this new topology, balancing can be achieved in a fast and an efficient manner.