Parallel Active Charge Balance Technique of Li-Ion Batteries Using Combined Phase Shifted and Boost DC-DC Converter

Cell balancing in Li-ion batteries is a very crucial task considering the effective loss of unusable charge that remains in the cells when one or more cells of the pack loses charge. The main idea of the cell balancing is to achieve a state of charge among cells where minimum or no charge of the battery remains unused while discharging and none of the cells overcharge in a response to charge the weaker cell to the full capacity. Several active cell balancing methods are available that mainly focus on same limb or string cells balancing. In this article focus is made on charge transfer among parallel strings of the battery using combined Phase shifted and boost dc converters. The proposed cell balancing is very efficient in parallel charge balancing and can improve over all balancing efficiency of the BMS in achieving both same and parallel limb balancing. The proposed topology has been evaluated using MATLAB/Simulink with the help of inbuilt Li-ion NMC cell model (3.7V, 2.050Ah) and the results are presented.