Research And Design Of Battery Management System For Reconfigurable Battery Packs

In traditional fixed series-parallel battery systems,the inconsistency of individual battery cells will be gradually amplified with the growth of usage time,resulting in energy utilization reduction and safety hazards in the energy storage system.In order to effectively solve these problems,the reconfigurable battery pack with power electronic switching devices changes the connection mode of battery cells into "flexible connection" controlled by software,which has a broad application prospect.However,the introduction of switching devices also makes the circuit topology of the battery pack more complex and poses higher requirements for the battery management system.Therefore,this thesis focuses on the topology and battery management system of the reconfigurable battery pack and the main tasks are as follows:1.Study on the improvement of the topology and key management technologies of reconfigurable battery pack.Firstly,an improved single cell-cluster two-stage switching topology is designed through the comparative analysis of existing topologies.After studying the dynamic reconfiguration technology of reconfigurable battery pack,criteria and isolation strategies for common faults and the selection control strategy when the energy demand changes are developed.Then,the equalization management technology of reconfigurable battery pack is studied,and the SOC-based charge/discharge equalization strategies are designed according to the improved topology.Finally,the overall design of reconfigurable battery pack and management system is completed.2.Hardware design of the battery management system for reconfigurable battery pack.According to the overall design plan,the battery pack and management system are modularized by function,including the main controller module,battery pack reconfiguration module,information acquisition module,etc.Following the master-slave structure,PCB design is carried out to integrate the reconfiguration circuit of battery pack and information acquisition circuit into the sub-circuit board,and the control and communication and other modules into the main circuit board to reduce the interference of components and facilitate maintenance and replacement.3.Software design of the battery management system for reconfigurable battery pack.The software design part is mainly for the software program design of each functional module.It mainly includes the system main program,information acquisition program,dynamic configuration program,equalization management program and upper computer display program.The upper computer realizes the monitoring of the battery information,the selection of the single unit and the control of the connection mode through the humancomputer interaction interface written by Visual software under Windows.4.Test and experiment.After completing the hardware and software interconnection,the test prototype is firstly tested for basic functions to verify the accuracy of information acquisition and SOC estimation,and the effectiveness of reconfiguration switch;then the fault experiment,selection control experiment,and equalization management experiment are conducted respectively,the experimental results show that the battery management system for reconfigurable battery packs has the ability to automatically isolate the faulty cells in the battery pack,select the number of cells in the battery pack to be connected and control the series-parallel connection of the battery pack through the host computer software.And after using the proposed equalization strategy,the capacity utilization rate of the battery packs in the discharged state is increased by 15.17%,the discharge time is increased by 27.63%,and all cells can reach the SOC limit and the inconsistency is significantly improved in the charged state.