Thermal Characteristics Analysis And Structural Design Of Energy Cube Based On Lithium Iron Phosphate

In recent years,with the "double carbon slogan",the scale of clean energy storage has become increasingly large.Storing clean energy in the grid and transporting it to the home will cause unavoidable energy consumption.In this paper,we design a home portable energy storage device,Energy Magic,which can be expanded according to the environmental conditions of the home.The lithium-ion battery with good thermal stability is selected,and the thermal parameters of the battery are identified and the battery simulation model is built to verify the realism of the simulation model through experiments;the two high heat-producing regions of the battery module and the inverter are studied to obtain their thermal characteristics.The structural design of the energy cube is carried out,and the mechanical performance simulation analysis of the designed structure is combined with the actual working conditions.The influence weights of different factors are observed through orthogonal tests,optimization of weak points is implemented according to the simulation results,and experimental verification studies are carried out.The main research contents are as follows;(1)The internal structure,working principle,heat generation mechanism and heat transfer mechanism of lithium-ion batteries are studied,and lithium iron phosphate is selected as the battery pack cell according to the advantages and disadvantages of lithium-ion battery types.The lithium-ion battery is tested for thermal property parameter identification and related heat generation parameters,and a set total model is established based on Bernadi’s heat generation equation,and the accuracy and validity of the model are experimentally verified.(2)In this paper,three battery pack arrangement structures are designed and the corresponding battery pack thermal models are established in COMSOL software.By analyzing the temperature field of three different battery pack structures under natural heat dissipation,the arrangement structure with structure B as the energy tesseract was determined and then natural heat dissipation verification experiments were conducted.Adding fans to analyze the heat dissipation effect of different aircooling factors and adopting natural heat dissipation under comprehensive consideration,it is found that the maximum discharge multiplier of the battery module under this condition is selected as 1.5C.The power of the inverter is determined according to the current magnitude and the thermal characteristics are analyzed.The results show that the inverter temperature at full load meets the requirements of the operating conditions.(3)The structural design is carried out according to the actual working condition requirements,selecting the main materials of the battery shell,designing the chassis,shell,interface end face,battery module and expansion bracket,etc.Pro/e was used to build the 3D model and imported into Hyperworks for meshing,connection relationship setting,contact type and constraint setting,laying the foundation for importing Abaqus to do finite element analysis.(4)The finite element mechanical simulation was performed on the mesh model imported into Abaqus.In practical application,the ultimate equivalent force is20.2 MPa.in the modal analysis,the lowest resonant frequency is 48.8 Hz.for the battery pack X,Y,Z three directions of random vibration analysis,the analysis results obtained λσ are greater than 3σ.The battery shell was subjected to different angles of drop force analysis,and was subjected to a maximum equivalent force of 59.8 MPa at an inclination of 15°,and the simulation test results all met the structural strength requirements.The orthogonal test was designed to study the degree of influence of the drop height,drop tilt angle and battery pack mass on the drop force,and it was found that the height and tilt angle had a greater influence on the drop force.For the weak point of the drop structure,we optimized the material,selected and replaced the high quality cushioning material and conducted drop verification experiments,which proved that the battery pack shell did not break and met the force strength requirements.