CN-121997559-A - Equivalent dynamics modeling method for aging of battery module

Abstract

The invention provides an equivalent dynamics modeling method for aging of a battery module. The method comprises the steps of obtaining the compression mechanical response of the aging battery cell, obtaining the equivalent stiffness damping coefficient of the aging battery cell, establishing a multi-body dynamics model of the module in different aging states, applying different extrusion speeds to the module, judging whether the battery module is internally short-circuited or not according to design requirements, and the like. The method can provide reference for efficient simulation and mechanical safety evaluation of the battery pack system module. By using the method, the research and development personnel can efficiently and rapidly acquire the deformation of the module battery cells in different aging states under different extrusion working conditions, and judge whether the module battery cells have internal short circuits according to design standards or related standards.

Inventors

• LIU BINGHE
• LIU YUE
• ZHANG XIAOXI
• PAN YONGJUN

Assignees

• 重庆大学

Dates

Publication Date

20260508

Application Date

20251226

Claims (7)

1. 1. The equivalent dynamics modeling method for aging of the battery module is characterized by comprising the following steps of: S1) acquiring mechanical response information of the battery cell under extrusion working conditions in different ageing states; s2) extracting force-displacement curves of the battery cells in different aging states based on mechanical response information, and fitting to obtain equivalent stiffness damping coefficients of the battery cells in the corresponding aging states; s3) based on equivalent stiffness damping coefficients, the battery cells in different aging states are equivalent to spring damping models with different stiffness damping characteristics; s4) utilizing a recursion method to carry out series combination on the spring damping model of the battery core and the rubber-filled spring damping system, and establishing a multi-body dynamics model of the battery module containing information of different aging states; S5) applying preset extrusion speed to the multi-body dynamics model, and obtaining deformation information of each battery cell monomer in the battery module by solving a dynamics equation; S6) comparing the deformation information of the battery cell monomer with a preset safety threshold value, and judging whether the battery cell is internally shorted.
2. 2. The equivalent dynamics modeling method for aging of a battery module according to claim 1 is characterized in that in the step S1), a commercial cylindrical battery is selected as an object, extrusion test data of the cylindrical battery under different cycle times are obtained through experimental tests or reference to an existing database, the cycle times are used for representing the aging state of an electric core, and the higher the cycle times are, the higher the aging degree is.
3. 3. The method for modeling equivalent dynamics of aging of a battery module according to claim 2 is characterized in that in the step S2), the extraction force-displacement curve is required to meet the condition that the battery cells in different aging states are ensured to be under the same test working conditions when data are acquired, the test working conditions comprise the same extrusion speed, the same test equipment or simulation model setting, and the only variable is the aging information of the battery cells.
4. 4. The method for modeling the equivalent dynamics of aging of the battery module according to claim 1 is characterized in that in the step S2), the specific method for obtaining the equivalent stiffness damping coefficient through fitting is to perform piecewise fitting according to the shape characteristics of a force-displacement curve, wherein the electric core is equivalent to a pure spring system in a linear response stage of the curve, and the electric core is equivalent to a spring damping system in a nonlinear response stage of the curve.
5. 5. The method for modeling equivalent dynamics of aging of a battery module according to claim 1, wherein in step S5), the state matrix of each cell in the module is expressed as: The kinetic equation for the modular system is expressed as: in the formula, A state matrix which is a module; the state vector of the ith battery cell contains displacement and rotation information, and the superscript T represents transposition; M is a mass matrix, ̈ represents a second derivative; A jacobian matrix that is a constraint; Is a Lagrangian multiplier; a force applied externally; Is a velocity dependent force; is a mechanical information matrix.
6. 6. The method for modeling equivalent dynamics of battery module aging according to claim 1, wherein in step S5), the dynamics simulation software ADAMS is selected as a tool for performing dynamics simulation analysis.
7. 7. The method for modeling equivalent dynamics of aging of a battery module according to claim 1, wherein in the step S6), the preset safety threshold is a short-circuit displacement value defined in a related design standard, and if the maximum deformation of the battery cell exceeds the short-circuit displacement value, internal short-circuit of the battery cell is determined.

Description

Equivalent dynamics modeling method for aging of battery module Technical Field The invention relates to the technical field of new energy automobiles, in particular to an equivalent dynamics modeling method for aging of a battery module. Background With the rapid development of the new energy automobile industry, the holding capacity of electric automobiles is remarkably increased. The power battery pack is used as a core energy source of the electric automobile, and the safety of the power battery pack is directly related to the running safety of the automobile and the life and property safety of drivers and passengers. In the actual running process of the vehicle, the battery pack inevitably faces complex working conditions such as collision, scraping, foreign matter invasion and the like. The working conditions are very easy to cause irreversible structural damage to the battery pack, and the chain reaction such as thermal runaway, electrolyte leakage and the like can be caused when the battery pack is severe, so that disastrous accidents such as fire and explosion are finally caused, and the serious threat is formed to road traffic safety. Particularly, if the potential damage caused by micro extrusion is not evaluated in time, the prediction of the residual life of the battery pack is misaligned, and the potential hazard is a great hidden danger for safe burying of subsequent driving. Therefore, the mechanical safety evaluation of the battery pack system is an important link for ensuring the safety of the electric automobile. At present, a finite element method is mainly adopted in the industry to build a refined model of a battery module or a battery pack so as to simulate and calculate the mechanical response of the battery module or the battery pack under mechanical load. However, the prior art has mainly the following disadvantages: A. The calculation efficiency is low, and the requirement of rapid iterative design cannot be met. In order to ensure accuracy, the traditional finite element model often comprises millions of grid units, so that the degree of freedom in the calculation process is extremely high, the solving time is long, and the requirement on calculation hardware resources is extremely high. This makes multi-regime, large-scale parametric analysis extremely difficult at the beginning of the design. B. The existing model does not consider the influence of cell aging on mechanical properties, resulting in full life cycle safety assessment misalignment. The existing simulation evaluation method adopts fixed material parameters for calculation. In fact, as the number of charge and discharge cycles of the battery increases, the winding structure and chemical state inside the battery cell change, resulting in significant changes in the macroscopic mechanical properties. The prior art ignores the dynamic evolution process, and cannot truly reflect the deformation and damage mechanism of the battery module in the middle and later life when being extruded, so that misjudgment on the safety of the battery pack of an old vehicle is possibly caused, and serious potential safety hazards exist. Therefore, it is highly desirable to provide a fast and battery pack system module equivalent modeling method that takes cell aging into consideration. Disclosure of Invention The invention aims to provide an equivalent dynamic modeling method for aging of a battery module, which aims to solve the problems in the prior art. The technical scheme adopted for realizing the purpose of the invention is that the equivalent dynamics modeling method for aging of the battery module comprises the following steps: s1) acquiring mechanical response information of the battery cell under the extrusion working condition under different ageing conditions. S2) extracting force-displacement curves of the battery cells in different aging states based on the mechanical response information. And fitting to obtain the equivalent stiffness damping coefficient of the battery cell in the corresponding aging state. S3) based on equivalent stiffness damping coefficients, the battery cores in different aging states are equivalent to spring damping models with different stiffness damping characteristics. And (5) equivalent filling glue in the battery module is used as a filling glue spring damping system. S4) utilizing a recursion method to carry out series combination on the spring damping model of the battery core and the rubber filling spring damping system, and establishing a multi-body dynamics model of the battery module containing different ageing state information. S5) applying preset extrusion speed to the multi-body dynamics model, and obtaining deformation information of each battery cell monomer in the battery module by solving a dynamics equation. S6) comparing the deformation information of the battery cell monomer with a preset safety threshold value, and judging whether the battery cell is internally shorted. Further, i