A modularized active cell balancing of lithium-ion battery packs using buck-boost converter for electric vehicle applications

Achieving optimal balancing speed and efficiency in lithium-ion battery packs is a growing challenge. This article proposes a novel modularized active cell balancing approach utilizing a buck-boost converter to address this issue. The system comprises two modules, each containing three cells with 3.7 V and 2200 mAh ratings. A two-stage balancing process was implemented in this article, starting with module balancing followed by cell balancing. Various simulation studies in static, charging, and discharging modes were conducted using the MATLAB Simulink platform to assess balancing performance. The simulation outcomes for module balancing show a balancing speed of 7.55 s and a balancing voltage of 10.45 V. The modularized cell balancing achieved a balancing speed of 9.4 s and a balancing voltage of 3.45 V. The modularized balancing efficiency was obtained as 96.7 %. The simulation results are validated with the field programmable gate array (FPGA) based real-time simulator OPAL-RT (OP5700). The proposed topology effectively balances cells, achieving a voltage difference of only 18 mV between MATLAB simulation and real-time simulation, demonstrating its reliability and capability to enhance balancing speed and efficiency significantly.