Research on equalization of lithium battery pack based on Buck converter

The available capacity of the series lithium battery is limited by the capacity of the single battery. The capacity difference of the single battery is easy to cause the phenomenon of overcharge and over discharge, and it will cause deflagration problem seriously. In order to increase the available capacity, an equalization circuit based on Buck converter is proposed in this paper. The equalization circuit includes a Buck converter and a switching bridge structure, which improves the flexibility of the circuit while reducing the number of switching devices. With the state of charge (SOC) of a single battery as the equilibrium variable, the "valley filling" of the single battery with the lowest SOC and the "peak cutting" of the battery pack can be realized. The simulation results based on MATLAB/Simulink show that compared with the control group without using equalization circuit, the available capacity of this scheme is increased by10 %,12.5 % and 13.7 % respectively under charging, discharging and resting conditions, which proves the practicability of this scheme.