Dynamic Resistance Battery Equalization for Capacity Optimization of Parallel-Connected Cells

This paper proposes a dynamic resistance equalization for parallel battery configuration, which can improve the equalization performance, optimize the battery capacity, and reduce loss dissipation. From the estimated SOC rate of battery cells, the switches in the equalization circuit are controlled to change the equivalent series impedance of individual branches, which regulates the current flow to maximize SOC utilization. The performance of the proposed technique is verified by simulations of a parallel connected configuration of four 18650 Li-ion battery cells with 3.7V/2.6Ah individually. The results show that the SOCs are balanced within 1% difference, all cells are fully charged or discharged at the same time, and the branch current is confined to safety range with less power dissipation over the conventional method.