Research Of Lithium Iron Phosphate Battery Performance Simulation And Equalization Technology

With the increasing scarcity of oil resources and the ecological crisis is becomingincreasingly serious, followed by rising oil prices and the ongoing severe hazepollution, these phenomena are affecting our lives, the full development of newenergy vehicles is inevitable, this is not only a trend in the automotive industry, it isthe strategic direction of the country. Battery technology is the key to thedevelopment of electric vehicles, battery pack application technology is essential toensure the safe use of the battery, estimate battery status and extend battery life.Studying and establishing the battery performance model is the foundation of batterySOC estimation, equalization strategy research and vehicle performance simulation.Lithium iron phosphate (LiFePO4, referred to as LFP) battery performance isexcellent and has good prospects for development, through the LFP battery to startexperimental studies, establish an accurate battery performance simulation model, andbuild a battery equalization scheme which has a wide range of balanced good effect.First, the article analyzes the organization structure and operation mechanism ofthe LFP power battery, to make the intrinsic link of open circuit voltage, current,equivalent impedance, EMF, SOC and SOH (State of Health) and other physicalcharacteristics clearly, On the operating characteristics of the LFP batteries batterycharacteristic test, to obtain the characteristic curve. Comparing domestic and foreignmainstream battery performance model, drawing on the advantages of MassimoCeraolo model circuit structure to improve its equivalent impedance voltage source,to get the battery model in this paper. Model integrate the battery voltage hysteresischaracteristics, In the ohmic resistance and the polarization resistance precisiondemand is higher, to analyze the experimental data fitting model parameters.Secondly, according to the circuit structure and the mathematical relationship ofbattery model, build a battery performance simulation model in MATLAB/simulinksoftware environment, using UDDS, HPPC and other typical conditions to verify theaccuracy of the model, for each simulation, which added first to fourth order modeland model without hysteresis as compared to verify the accuracy and precision of theperformance of the simulation model, and ultimately determine the feasibility of thebattery model. Finally, analyze the mechanism and hazards arising from discordance of LFPbattery pack, obtain main solution to get a clear direction of a balanced system design.Analysis of battery inconsistency external manifestations and quantitative way,determine the battery equalization criterion.Compared to mainstream equalization circuit topology and its advantages anddisadvantages，choose energy storage inductors and MOSFET components, etc toestablish a adjacent balanced circuit structure which can work in each condition, it hasstrong expansion and low cost. Base on the battery performance model, the paper usefour batteries as an example to achieve a balanced circuit simulation model inSimulink. Design different battery capacity distribution scheme, control test in threeoperating states, analyze and compare the experimental results to verify thecorrectness of device parameters and validity of equilibrium model.