Comparison of Active Battery Balancing Systems

A quantitative model-based comparison of 10 active balancing circuits is presented for equalizing imbalanced cell energies of lithium-ion batteries. A mean current model approach is introduced for active balancing to describe energy transfers between battery cells for long charge/discharge operation. A Th233;venin model for 96 battery cells is used as a subsystem of a mid-size electric vehicle. In quasi-static simulations, FTP75 driving cycles are continuously repeated until the first cell is discharged from initial full charge. Simulation results are compared for cases of new and aged cells with different capacity distributions concerning equalization speeds and final differences of cell energy.