Balancing and SOC Estimation in a Battery Management System for Electric Vehicle

This paper presents the implementation of a passive and an active cell balancing method using MATLAB/Simulink simulations. For passive balancing two variants were implemented: one using the cell voltage to determine whether balancing is needed, and the second one using the cell SOC. The SOC was estimated with Coulomb Counting and Extended Kalman Filter, comparing the two algorithm results, Extended Kalman Filter has smaller estimation error. The results show that the variant based on the SOC has higher performance. Active balancing was implemented using switched capacitors topology and energy is transferred from higher charged cells to lower charge ones, with higher efficiency than passive balancing