Research And Design Of Active Balance Control System For Decommissioning Battery Energy Storage

With the increasing environmental pollution and energy crisis,the new energy vehicle industry is developing rapidly.As the core of new energy vehicle,the amount of power battery has increased.However,the capacity of power battery will decrease with the increase of cycle times.When battery capacity drops to 80% of rated capacity,it will be forced to decommissibe because it can not meet the driving demand of new energy vehicle under complex driving conditions.In order to avoid the waste of energy and environmental pollution,the decommissioned power battery echelon use in energy demand can lower places,the biggest bottleneck restricting retired battery echelon use is to solve the battery consistency problem,this paper is devoted to the study of retired battery energy storage using active balancing control system.The internal structure,working principle and main performance parameters of Li ion battery are introduced.The reasons and hazards of lithium battery inconsistency are summarized.The purpose and significance of battery equalization is discussed.The difference of the main performance parameters between the ex factory battery and the decommissioning battery is compared and analyzed.The necessity and the specific method of the battery capacity re calibration is pointed out,and the SOC estimation algorithm of OCV-AH based on the new calibration capacity is put forward.Comparative analysis of the current commonly used balanced circuit topology,the existing equalization scheme of low efficiency,not easy to expand,combined with the advantages and disadvantages of centralized distributed topology balanced topology and the proposed double balanced topology of bi-directional BUCK-BOOST circuit based on the group with the centralized inductance active equalization circuit,realize the monomer of two-way flow of energy between the groups using the distributed inductance;active equalization circuit,realize the energy transfer between adjacent cell groups,good scalability.The structure and working process of the balance circuit between the group and the group are analyzed in detail.The common target variables such as capacity,open circuit voltage,working voltage and SOC are analyzed and compared,and SOC is chosen as the only index to measure battery consistency.With the equalization circuit between group equalization circuit and group,respectively formulate the corresponding balance control strategy between groups: considering various possible cases,classified as direct and indirect balance equilibrium;group based on the "partition" thought,sort and partition of state of charge of battery group in each section of retired battery,based on the number of equilibrium optimization the regional sub path set.Several sets of comparative experiments are set up.Through MATLAB simulation and experimental verification,the active equalization control system designed for decommissioning battery energy storage is suitable for static,charging,discharging state and different SOC distribution,and the equilibrium effect is very good,and the equilibrium efficiency is high.