A Generalized Modular Battery Pack Topology With Active Cell Balancing Technique

This article presents a novel generalized modular battery pack with any “<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</i>” parallel battery strings of any “<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">m</i>” series connected cells where ((<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">m</i>, <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</i>) <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\in \mathbb{Z}^{+}$</tex-math></inline-formula>). This novel battery pack prevents circulating current and also balances the entire battery pack using the proposed boost-based active cell balancing strategy. The proposed cell balancing topology employs only two active switches per cell and utilizes “<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</i>” inductors for a <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">m</i> × <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</i> cell battery pack, allowing efficient active balance throughout the pack. A detailed theoretical analysis is presented, and operating conditions are systematically derived to maximize output power and achieve optimal efficiency. The proposed topology and balancing technique are also simulated using MATLAB/Simulink for a three parallel strings of three series connected cells battery pack and the results are presented. These results are also experimentally verified using BAKH18650CIL battery cells in the laboratory. It could achieve cell balance while operating at 95.92% efficiency.