Composite layered equalization circuit for LiFePO4 battery pack of mine-used monorail

In continuous charging and discharging cycle of LiFePO4 battery pack of mine-used monorail, inconsistency among each single batteries will lead to overall performance degradation and shorten service life of the battery pack. Traditional battery pack equalization mode has long equalization time and complex control strategy. In order to solve the above problems, a composite layered equalization circuit was proposed based on Buck-Boost equalization circuit and flying-capacitor equalization circuit. Buck-Boost equalization circuits in bottom layer and middle layer are constructed according to binary tree structure, and flying-capacitor equalization circuit in top layer realizes energy transfer of any two batteries between three adjacent batteries, so that the batteries can not only transfer energy within layer to achieve equalization between adjacent batteries, but also transfer energy between layers to achieve equalization between non-adjacent batteries. The simulation results show that the composite layered equalization circuit greatly reduces equalization time and significantly improves battery voltage consistency.