Research On Lithium-ion Battery Management System And Active Balancing Strategy

Lithium-ion batteries have developed rapidly due to their advantages such as high efficiency and fast response.However,their characteristics are relatively complex,and various failure problems may occur during operation.Especially in large energy storage plants,where thousands of batteries form a large battery box,when a problem occurs in a single battery,it will quickly spread to the rest of the batteries,causing more serious accidents.Therefore,studying the management system and energy balance strategy of lithium-ion battery energy storage power stations is of great significance for the safe and efficient operation of energy storage power stations.In this paper,related research was carried out to address the issues of insufficient parameter acquisition and wiring difficulties in battery management systems.A battery management system was designed to achieve multi-parameter acquisition and remote wireless transmission of batteries;A hierarchical model predictive control equalization strategy was proposed to achieve safe and fast battery balancing.The main research content of this article is as follows:(1)Design the overall scheme of the battery management system.The main functions of the battery management system are analyzed,and the advantages and disadvantages of different methods are analyzed.The overall design scheme of the battery management system designed in this article is given.(2)Aiming at the shortcomings of the ampere-hour integration method in estimating SOC,when designing the algorithm,considering the influence of coulomb efficiency of lithium ion batteries at different charging and discharging rates,lithium ion batteries at different charging and discharging rates were tested,and the correction coefficients for lithium ion batteries at different charging and discharging rates were obtained;Conduct experiments to determine the relationship between battery capacity and cycle times for the capacity loss of lithium ion batteries during aging,as a correction factor to improve the estimation accuracy;In order to achieve initial SOC measurement,a charge/discharge SOC-OCV calibration was performed,and its average value was taken to reduce the impact of hysteresis voltage.(3)Aiming at the current active balancing strategy that causes the battery’s operating current to exceed its limits,resulting in severe heat generation and reduced battery life,a multilayer inductance balancing circuit is adopted to divide the batteries in the battery pack into different modules based on the circuit characteristics,and relevant models are established.Based on the established model and the constraints of the equalization system,a hierarchical model predictive control equalization strategy is proposed.The particle swarm optimization algorithm is used to calculate the equalization current of the battery module layer by layer,reducing the complexity of the calculation process,achieving control of the battery operating current during equalization,ensuring the normal operation of the lithium-ion battery,reducing the heat generation and life loss of the battery,and improving the equalization speed of the battery pack,Achieving safe and fast balancing of lithium batteries.(4)Aiming at the problems of insufficient parameter collection and wiring difficulties in the current lithium battery management system,a battery management system is researched and designed to achieve multi-parameter collection during battery operation.Technologies such as Zig Bee and NB-Io T are used to achieve wireless data transmission,reducing wiring and maintenance difficulties.By cooperating with the designed host computer,visualization of battery parameters is achieved,improving the safety of energy storage power stations.(5)Functional verification and testing of the system have been carried out.According to the functional requirements,the designed lithium-ion battery management system was tested,and the test results showed that the designed system can achieve functions such as data monitoring,data transmission,and fault warning during battery operation.