Modeling method and system of battery pack thermal model

Abstract

The invention relates to the technical field of battery data modeling, in particular to a modeling method and system for a battery pack thermal model. The method comprises the following steps: determining the positions of single batteries in the battery pack; identifying a single body topological structure of the position of the single battery body, and collecting a single body electric temperature parameter of the position of the single battery body; performing electric temperature gradient difference measurement and calculation on the single electric temperature parameters to generate single electric temperature difference data; according to the method, through a data processing technology and a simulation modeling technology, the topological structure of the single battery is analyzed, and the electric temperature parameters of the single battery are combined to track the thermal resistance flow path, so that the battery pack thermal model is constructed, and the thermal state of the battery pack is completely presented, thereby improving the display precision of the battery pack thermal model; and targeted battery pack heat dissipation optimization is performed based on the thermal imbalance region characteristics, so that the thermal imbalance problem can be effectively identified and solved, and the thermal management efficiency and the performance stability of the battery pack are remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of battery data modeling, and in particular to a modeling method and system for a battery pack thermal model. Background Art

[0002] Early battery thermal models mainly used lumped parameter models, which regarded the battery as a whole and described the thermal behavior of the battery by simplifying assumptions. For example, Hallaj established a one-dimensional lumped parameter lithium-ion battery thermal model to simulate the temperature distribution of cylindrical lithium-ion batteries with enlarged capacity under different cooling conditions. With the in-depth understanding of the physical and chemical processes inside the battery, the electrochemical-thermal coupling model has gradually become a research hotspot. This model combines the conservation relationship of charge, mass and energy in the electrochemical reaction process with thermal behavior. However, most of the existing thermal models use lumped parameter models or simplified electrochemical-thermal coupling models. These models cannot accurately describe the complex temperature distribution inside the battery pack. In a multi-cell battery pack, it is difficult to accurately reflect the heat transfer and temperature distribution between cells. In addition, when simulating the operation of the battery pack, the existing thermal models have difficulty in identifying the thermal imbalance area and ignore the thermal resistance flow path inside the battery pack, resulting in insufficient model accuracy. Summary of the invention

[0003] Based on this, it is necessary to provide a modeling method and system for a battery pack thermal model to solve at least one of the above technical problems.

[0004] To achieve the above object, a method for modeling a battery pack thermal model is provided, the method comprising the following steps: Step S1: determining the battery cell position inside the battery pack; identifying the cell topology structure at the battery cell position, and collecting the cell electrical temperature parameters at the battery cell position; Step S2: Calculate the electric temperature gradient difference of the electric temperature parameters of the cells to generate electric temperature difference data of the cells; perform a temperature field distribution detection on the cell topology structure of the cells using the electric temperature difference data of the cells, and draw a temperature distribution diagram of the cells; identify the thermal resistance flow path of the cells in the temperature distribution diagram of the cells; and construct an initial thermal model of the battery pack based on the cell topology structure and the thermal resistance flow path of the cells; Step S3: inputting the battery cell operating parameters into the initial thermal model of the battery pack, and performing a thermal energy state evaluation within the pack to obtain thermal energy state data of the battery pack; performing thermal imbalance region identification on the thermal energy state data of the battery pack to generate thermal imbalance region data; Step S4: marking the thermally unbalanced battery cells of the initial thermal model of the battery pack according to the thermally unbalanced region data, and performing regional heat dissipation optimization on the thermally unbalanced battery cells to obtain a thermal model of the battery pack.

[0005] By determining the position of the battery cells inside the battery pack, the present invention can clarify the specific layout of each cell in the battery pack, providing a basis for subsequent accurate modeling. By identifying the cell topology structure, the connection relationship between the battery cells can be fully understood, and the cell electrical temperature parameters of the battery cell position can be accurately collected. This process ensures the accuracy and comprehensiveness of the collected data, and provides reliable data support for subsequent operations such as electrical temperature gradient difference measurement and temperature field distribution detection, so that subsequent modeling can truly reflect the electrical temperature characteristics inside the battery pack; by measuring the electrical temperature gradient difference of the cell electrical temperature parameters, accurate cell electrical temperature difference data can be generated, thereby clearly presenting the unevenness of the electrical temperature distribution between the battery cells. The cell electrical temperature difference data is applied to the cell topology structure to perform cell temperature field distribution detection, and the cell temperature distribution diagram is drawn, which can intuitively display the temperature distribution inside the battery pack and help discover potential thermal management problems. Identifying the cell thermal resistance flow path of the cell temperature distribution diagram can clarify the heat conduction path in the battery pack, providing a key basis for building the initial thermal model of the battery pack. The initial thermal model of the battery pack constructed based on the monomer topology and the monomer thermal resistance flow path can more accurately reflect the thermal characteristics of the battery pack and provide a basis for the subsequent thermal energy state evaluation and optimization; the battery monomer operating parameters are input into the initial thermal model of the battery pack, and the thermal energy state evaluation is performed within the group. The obtained thermal energy state data of the battery pack can fully reflect the thermal energy distribution of the battery pack in actual operation. The thermal imbalance area is identified for the thermal energy state data of the battery pack. The generated thermal imbalance area data can accurately locate the area with thermal imbalance problems in the battery pack, provide a clear direction for the subsequent targeted heat dissipation optimization, and help improve the overall thermal management performance of the battery pack. According to the thermal imbalance area data, the thermal imbalance battery monomers of the initial thermal model of the battery pack are marked, and the regional heat dissipation optimization of the thermal imbalance battery monomers is performed. The final thermal model of the battery pack can more accurately reflect the actual thermal characteristics of the battery pack. Through this optimization, the temperature of the thermal imbalance area can be effectively reduced, the temperature difference inside the battery pack can be reduced, and the service life and safety of the battery pack can be improved. Therefore, the present invention uses data processing technology and simulation modeling technology to analyze the topological structure of battery cells and track the thermal resistance flow path in combination with the electrical and temperature parameters of the cells to construct a battery pack thermal model and fully present the thermal state of the battery pack, thereby improving the display accuracy of the battery pack thermal model; targeted battery pack heat dissipation optimization is performed based on the characteristics of the thermal imbalance area, which can effectively identify and solve the thermal imbalance problem and significantly improve the thermal management efficiency and performance stability of the battery pack.

[0006] Preferably, step S1 comprises the following steps: Step S11: spatially locating each battery cell inside the battery pack by using an electromagnetic induction positioning device, obtaining the coordinates of the battery cell inside the battery pack, and recording them as cell coordinate data; Step S12: determining the arrangement order and the cell spacing of the battery cells according to the cell coordinate data; encoding the position information of the battery cells based on the arrangement order and the cell spacing to obtain the battery cell position; Step S13: determining the connection relationship of adjacent battery cells according to the battery cell positions; identifying the cell topology of the battery cell connection relationship; Step S14: selecting a plurality of measuring points in the battery pack, wherein the measuring points are selected at three fixed positions of the positive electrode, the negative electrode, and the surface midpoint of the battery cell; Step S15: setting the parameters of the electrical temperature parameter acquisition device, including the voltage acquisition range of 0-5V, the current acquisition range of 0-10A, the temperature acquisition range of -20°C to 80°C, and the acquisition accuracy of 0.01V, 0.01A and 0.1°C respectively; Step S16: The first collection is performed at the first minute after the battery cell starts charging and discharging, the second collection is performed at the fifth minute, and the third collection is performed at the tenth minute, and each collection lasts for 1 second; Step S17: classify and store the voltage parameters, current parameters and temperature parameters to form single-cell electrical and temperature parameters.

[0007] The present invention spatially locates each battery cell inside the battery pack through an electromagnetic induction positioning device, can accurately obtain the coordinates of the battery cell in the battery pack, and record them as cell coordinate data, to determine the arrangement order of the battery cells, the cell spacing and provide an accurate coordinate basis for encoding the position information, thereby ensuring the accuracy and reliability of the battery cell position information; the arrangement order and cell spacing of the battery cells are determined according to the cell coordinate data, and the position information of the battery cells is encoded based on the arrangement order and the cell spacing, which can clearly characterize the specific position of each battery cell in the battery pack, clarify the reasonable selection of subsequent measurement points and the precise positioning of the acquisition of electrical and temperature parameters; the connection relationship between adjacent battery cells is determined according to the battery cell position, and the cell topological structure of the battery cell connection relationship is identified, which can accurately reflect the connection layout inside the battery pack, clarify the electrical connection and heat transfer relationship between each battery cell, so that the thermal model can truly reflect the heat conduction and electrochemical behavior inside the battery pack; multiple measurement points are selected in the battery pack, and the measurement points are selected at three fixed positions of the positive electrode, negative electrode and surface midpoint of the battery cell. This measurement point selection method can fully cover the key parts of the battery cell, ensuring that the collected electrical and temperature parameters can fully reflect the electrochemical reactions and heat generation of the battery cell during the charging and discharging process; setting the parameters of the electrical and temperature parameter acquisition equipment, including the voltage acquisition range of 0-5V, the current acquisition range of 0-10A, and the temperature acquisition range of -20℃ to 80℃, and the acquisition accuracy is 0.01V, 0.01A and 0.1℃ respectively; the first acquisition is carried out in the first minute after the battery cell starts charging and discharging, the second acquisition is carried out in the fifth minute, and the third acquisition is carried out in the tenth minute, and each acquisition lasts for 1 second. This acquisition time arrangement can obtain multiple sets of data at the key stage of the initial charging and discharging of the battery cell, and capture the changes in the electrical and temperature characteristics of the battery cell at different charging and discharging stages; the voltage parameters, current parameters and temperature parameters are classified and stored, so that the required parameters can be called quickly and accurately when constructing the thermal model of the battery pack, thereby improving the efficiency and accuracy of thermal model construction.

[0008] Preferably, the step S2 of calculating the difference in electrical temperature gradient of the electrical temperature parameters of the monomer includes: Marking the battery cell measurement points of the battery cell electrical temperature parameters, determining the positive and negative electrode areas of the battery according to the battery cell measurement points, and determining the body center area of ​​the battery cell surface based on the positive and negative electrode areas of the battery; The temperature difference between the positive and negative regions of the battery is calculated to obtain the temperature difference between the positive and negative regions; the voltage difference between the positive and negative regions of the battery is calculated to obtain the voltage difference between the positive and negative regions; the current difference between the positive and negative regions of the battery is calculated to obtain the current difference between the positive and negative regions; Extract the temperature value, voltage value and current value of the center area of ​​the battery cell surface; The temperature difference between the positive and negative electrodes, the voltage difference between the positive and negative electrodes, and the current difference between the positive and negative electrodes are numerically compared with the temperature value, voltage value, and current value of the body center area, respectively, and arranged according to the numerical gradient to obtain the electrical temperature gradient difference data.

[0009] The present invention marks the battery cell measurement points for the single cell electrical temperature parameters, which can clarify the specific source location of each measurement data, and provide an accurate spatial positioning basis for subsequent regional division and parameter calculation. The positive and negative electrode regions of the battery are determined based on the measurement points, and the key functional areas inside the battery cell are further clarified, making the electrochemical behavior and thermal characteristics analysis of the battery cell more targeted; the temperature difference, voltage difference and current difference of the positive and negative electrode regions of the battery are calculated, which can quantify the electrical temperature difference between the positive and negative electrode regions, and intuitively reflect the thermal effect and electrochemical reaction imbalance between the positive and negative electrodes of the battery cell during the charging and discharging process; at the same time, the body center region temperature value, body center region voltage value and body center region current value of the battery cell surface are extracted; the positive and negative electrode temperature difference, the positive and negative electrode voltage difference and the positive and negative electrode current difference are numerically compared with the body center region temperature value, the body center region voltage value and the body center region current value, respectively, and arranged according to the numerical gradient, which can clearly present the changes in the electrical temperature gradient between different regions inside the battery cell; through the electrical temperature gradient difference data, the heat distribution inside the battery cell and the unevenness of the electrochemical reaction can be accurately judged.

[0010] Preferably, the step S2 of performing a temperature field distribution test on the topological structure of the monomer using the monomer electrical temperature difference data and drawing a monomer temperature distribution diagram comprises: The temperature difference data of the single cell is processed in time series, and the temperature change rate of each single cell at different time points is calculated to obtain the temperature change rate of the single cell; According to the monomer topological structure, determine whether the single battery is at the edge or the middle position, and obtain the battery position data; Determine the arrangement of the cell topology and classify the arrangement into series cells and parallel cells; Based on the battery location data, the series batteries and parallel batteries are used to calculate the heat dissipation space of the single battery to obtain the heat dissipation space data of the single battery; Determine the local temperature data of the single cell according to the heat dissipation space data of the single cell; Conduct temperature field statistics on the local temperature data of the monomer and detect the heat distribution data of the temperature field; Import the temperature field heat distribution data into the drawing tool, and map the data points into a two-dimensional coordinate system according to the temperature gradient, where the coordinate axes represent the physical position and temperature value of the battery pack, respectively, to obtain a single cell temperature distribution diagram.

[0011] The present invention performs time series analysis on the electric temperature difference data of the battery and calculates the electric temperature change rate, which can accurately capture the dynamic characteristics of the battery monomer during the charging and discharging process and fully understand the thermal evolution law of the battery under different working conditions; the position of the battery is determined based on the monomer topological structure, and the spatial distribution characteristics of the battery monomer in the battery pack can be clarified. The batteries at the edge and the middle position have significant differences in temperature distribution due to different heat dissipation conditions; clarifying the arrangement mode of the single battery (series or parallel) is the basis for understanding the overall thermal behavior of the battery pack, and there are differences in current path and heat distribution between series and parallel batteries; through heat dissipation space measurement, the heat dissipation capacity of each battery monomer can be quantified, the edge battery usually has better heat dissipation conditions, while the heat dissipation of the middle battery is limited; the correlation analysis of the heat dissipation space data and the local temperature data can reveal the actual temperature distribution of the battery monomer, and the battery monomer with a smaller heat dissipation space often shows a higher temperature; statistics on the local temperature data and heat distribution detection can generate the overall temperature field characteristics of the battery pack, and by mapping the temperature field data to a two-dimensional coordinate system, the temperature distribution of the battery pack can be intuitively displayed, and the relationship between the temperature gradient and the physical position of the battery can be clearly presented, providing a visual basis for the thermal management optimization of the battery pack.

[0012] Preferably, the monomer thermal resistance flow path of the monomer temperature distribution diagram identified in step S2 includes: The monomer temperature distribution map is divided into regions according to the temperature range, and the temperature range of each region is set to 5°C; In each temperature gradient region, the temperature difference between adjacent single cells is measured, and the ratio of the temperature difference to the distance between adjacent single cells is calculated to obtain temperature-distance difference ratio data; If the temperature-distance difference ratio data is greater than 0.3°C / cm, it is preliminarily determined that the single cell corresponding to the temperature-distance difference ratio data is the starting point of the thermal resistance flow path; Determine the direction of the thermal resistance flow path based on the starting point of the thermal resistance flow path; if the single cells are connected in parallel, the direction of the thermal resistance flow path is perpendicular to the current flow direction; if the single cells are connected in series, the direction of the thermal resistance flow path is along the current flow direction; The intensity of the thermal resistance flow path is determined by comparing the temperature difference between the temperature gradient regions. The greater the temperature difference between the temperature gradient regions, the higher the intensity of the thermal resistance flow path. The direction and intensity of the thermal resistance flow path are marked on the monomer temperature distribution diagram with red lines, and the marked thermal resistance flow path is superimposed on the monomer temperature distribution diagram to form the monomer thermal resistance flow path.

[0013] The present invention can clearly identify the distribution of different temperature gradients inside the battery pack by dividing the single cell temperature distribution map into regions with a fixed temperature range (5°C); by measuring the temperature difference between adjacent single cells and calculating the temperature-distance difference ratio data, the relationship between temperature change and spatial distance can be quantified. This process provides key parameters for identifying the thermal resistance flow path and accurately locates the obstruction point of heat transfer; setting the threshold value of the temperature-distance difference ratio (0.3°C / cm) as the basis for judging the starting point of the thermal resistance flow path can effectively screen out the key position where heat transfer is obstructed. This judgment standard provides a clear starting point for the subsequent tracking and analysis of the thermal resistance flow path; determining the direction of the thermal resistance flow path according to the connection mode of the single cell (series or parallel) can accurately reflect the heat transfer path in the battery pack; determining the strength of the thermal resistance flow path by comparing the temperature difference between different temperature gradient regions can quantify the degree of heat transfer obstruction; the larger the temperature difference, the higher the strength of the thermal resistance flow path; marking the direction and strength of the thermal resistance flow path in a visual way on the single cell temperature distribution map can intuitively display the heat transfer path and obstruction inside the battery pack. This overlay approach provides a comprehensive and intuitive visualization tool for thermal characteristics analysis of battery packs, helping to optimize the thermal management system of battery packs.

[0014] Preferably, the step S2 of constructing the initial thermal model of the battery pack based on the cell topology and the cell thermal resistance flow path includes: Convert the cell topology and the cell thermal resistance flow path into a battery cell file, and import the battery cell file into Solidworks software; Set the single cell as a thermal network node according to the single cell topology, determine the arrangement, connection structure and battery layout of the single cell, and mark the position and size of each single cell; The thermal resistance flow path is set as the connecting edge between the thermal network nodes, and the thermal resistance parameters between the nodes are set; Connect the thermal resistance flow paths of adjacent single cells; if they are series cells, the current directions are connected sequentially; if they are parallel cells, the current directions are connected perpendicular to the parallel currents; The Solidworks simulation function is started to build an initial thermal model of the battery pack.

[0015] The present invention realizes the digital construction of the thermal model of the battery pack by converting the single cell topology structure and the thermal resistance flow path into a battery cell file and importing it into the Solidworks software. The single cell is set as a thermal network node, and its arrangement, connection structure and layout are clearly defined, and the position and size information are marked, which can accurately reflect the physical structure and electrothermal characteristics of the battery pack; the thermal resistance flow path is set as the connecting edge between the nodes, and the thermal resistance parameters are configured, which can quantify the heat transfer characteristics inside the battery pack; the thermal resistance flow path is connected according to the battery connection mode (series or parallel), which can accurately reflect the transfer direction of current and heat, and combines the electrical and thermal characteristics of the battery pack to provide complete path information for the simulation of the thermal model; starting the Solidworks simulation function can perform simulation analysis of the initial thermal model based on the thermal network model constructed above, and can simulate the temperature distribution and heat transfer of the battery pack under different working conditions.

[0016] Preferably, the step S3 of inputting the battery cell operating parameters into the initial thermal model of the battery pack and evaluating the thermal energy state within the pack includes: Inputting the battery cell operating parameters into the initial thermal model of the battery pack; Set the initial conditions of the battery cell temperature, and set the initial temperature to 25°C and the coolant temperature to 20°C; Set the battery cell operation mode to intermittent charge and discharge, and set the charge and discharge current to 1A and the charge and discharge voltage to 5V; Continuously monitor the temperature values ​​of the middle battery and the batteries on both sides of the group, and calculate the temperature difference between the temperature values ​​of the middle battery and the batteries on both sides of the group to obtain the temperature aggregation data within the group; Mark the temperature aggregation space of the temperature aggregation data within the group, and divide the temperature aggregation space into temperature aggregation points; The thermal energy parameters around the temperature gathering point are monitored incrementally with a circle of 0.1 cm radius to obtain the thermal energy diffusion data within the group; The thermal energy diffusion data within the group is subjected to diffusion gradient identification, and the thermal energy state of the diffusion gradient is evaluated to obtain the thermal energy state data of the battery group.

[0017] The present invention can simulate the dynamic thermal behavior of the battery pack under actual working conditions by inputting the operating parameters of the battery cell into the initial thermal model. Setting the initial temperature conditions (25°C for the battery cell and 20°C for the coolant) can provide a clear starting state for the thermal model, ensuring that the simulation results are consistent with the actual working conditions. Setting the intermittent charge and discharge mode and the specific current and voltage parameters can simulate the working state of the battery pack in actual applications, providing accurate operating conditions for the thermal model. By monitoring the temperature difference between the middle battery and the batteries on both sides, the temperature distribution non-uniformity inside the battery pack can be quantified and the temperature aggregation phenomenon can be identified. The temperature aggregation data is spatially marked and the temperature aggregation points are divided to clarify the specific location of the heat aggregation. Incremental monitoring with the temperature aggregation point as the center can capture the diffusion process of thermal energy in detail. The gradient identification and state evaluation of the thermal energy diffusion data can quantify the thermal energy distribution and transfer characteristics inside the battery pack, providing a scientific basis for optimizing the thermal management strategy of the battery pack.

[0018] Preferably, the step S3 of identifying the thermal imbalance area of ​​the battery pack thermal energy status data includes: Calculate the average temperature of the single cells in the battery pack according to the thermal energy status data of the battery pack; The difference between the temperature of each single battery and the average temperature is counted. When the difference exceeds 2°C, the battery is marked as a temperature abnormal point. If there are more than three temperature anomaly points in an area, and the temperature anomaly points are connected to each other, the area is determined to be a potential thermal imbalance area; Conduct voltage and current detection on cells in potential thermal imbalance areas, and set the voltage threshold to ±10% of the rated voltage of the cell, and the current threshold to ±20% of the rated current; When the voltage or current of a single cell exceeds the corresponding threshold, it is recorded as an abnormal state; if a single cell has abnormal temperature, abnormal voltage and abnormal current at the same time, it is determined that the battery cell has thermal runaway, and the potential thermal imbalance area where the battery cell is located is determined as the thermal imbalance area and recorded as thermal imbalance area data.

[0019] The present invention can provide an overall temperature reference value by calculating the average temperature of the single cells in the battery pack; by counting the difference between the temperature of the single cells and the average temperature and setting the difference threshold (2°C), it can accurately identify the battery cells with abnormal temperatures and effectively screen out the batteries with thermal runaway risks; by identifying the number and connection relationship of temperature abnormal points in the area, it can clearly identify the location of the potential thermal imbalance area, effectively identify the heat accumulation phenomenon inside the battery pack, and provide a basis for subsequent thermal runaway warnings; by performing voltage and current detection on the single cells in the potential thermal imbalance area and setting clear thresholds, it can further evaluate the electrochemical state of the battery and identify the overcharge or over-discharge that may occur in the battery during operation. By comprehensively evaluating the temperature, voltage and current abnormalities of the single cells, it is possible to accurately determine the battery cells with thermal runaway and the thermal imbalance area in which they are located.

[0020] Preferably, step S4 comprises the following steps: Step S41: dividing the thermal imbalance area data into a high-risk area, a medium-risk area and a normal area to determine the thermal imbalance division area; Step S42: color-marking the initial thermal model of the battery pack according to the thermal imbalance division area, wherein red indicates a high-risk area, yellow indicates a medium-risk area, and green indicates a normal area; determining the thermally unbalanced battery cell according to the model color marking information; Step S43: increasing the cooling wind speed of the area of ​​the thermally unbalanced battery cell and reducing the number of charge and discharge times to obtain optimized parameters of the thermally unbalanced battery; Step S44: transmitting the thermally unbalanced battery optimization parameters back to the initial thermal model of the battery pack to obtain the thermal model of the battery pack.

[0021] The present invention divides the thermal imbalance area data into high-risk areas, medium-risk areas and normal areas, which can clarify the regional distribution of different risk levels inside the battery pack, provide a clear regional basis for the subsequent thermal management strategy, and help to optimize the thermal management of the battery pack in a targeted manner. The initial thermal model of the battery pack is color-coded according to the thermal imbalance division area, where red represents the high-risk area, yellow represents the medium-risk area, and green represents the normal area. Through color marking, the thermal risk distribution inside the battery pack can be intuitively displayed, which is convenient for quickly identifying thermally unbalanced battery cells. This visualization method provides clear guidance for the formulation of thermal management strategies. Increasing the cooling wind speed in the area of ​​the thermally unbalanced battery cell and reducing the number of charge and discharge times can effectively reduce the temperature of the area and reduce heat accumulation. By adjusting the cooling wind speed and the number of charge and discharge times, the thermally unbalanced battery optimization parameters obtained can significantly improve the thermal state of the battery cell and reduce the risk of thermal runaway. The thermally unbalanced battery optimization parameters are fed back to the initial thermal model of the battery pack to obtain the optimized thermal model of the battery pack. This process can feed back the optimized parameters to the thermal model, further improve the thermal management strategy of the battery pack, and ensure that the battery pack maintains a good thermal balance during operation.

[0022] The present specification also provides a battery pack thermal model modeling system, which is used to execute the battery pack thermal modeling method as described above. The battery pack thermal model modeling system includes: The cell electrical temperature parameter acquisition module is used to determine the battery cell position inside the battery pack; identify the cell topology structure of the battery cell position, and collect the cell electrical temperature parameters of the battery cell position; The module for constructing the initial thermal model of the battery pack is used to measure the difference in the electrical temperature gradient of the electrical temperature parameters of the cells and generate the data of the electrical temperature difference of the cells; to detect the distribution of the temperature field of the cells on the topological structure of the cells using the electrical temperature difference data of the cells and draw the temperature distribution diagram of the cells; to identify the thermal resistance flow path of the cells in the temperature distribution diagram of the cells; and to construct the initial thermal model of the battery pack based on the topological structure of the cells and the thermal resistance flow path of the cells; The thermal state region detection module is used to input the battery cell operating parameters into the initial thermal model of the battery pack, and to evaluate the thermal energy state within the pack to obtain the thermal energy state data of the battery pack; to identify the thermal imbalance region of the thermal energy state data of the battery pack to generate the thermal imbalance region data; The thermal imbalance identification and optimization module is used to mark the thermally unbalanced battery cells in the initial thermal model of the battery pack according to the thermal imbalance area data, and to perform regional heat dissipation optimization on the thermally unbalanced battery cells to obtain the thermal model of the battery pack.

[0023] The present invention realizes accurate modeling and dynamic optimization of the temperature distribution inside the battery pack through the synergistic effects of single-cell electrical temperature parameter collection, initial thermal model construction, thermal state area detection, and thermal imbalance identification and optimization. It can accurately identify the thermal imbalance area and perform targeted heat dissipation optimization, thereby improving the thermal stability of the battery pack, optimizing the thermal management effect of the battery pack, extending the battery life, and ensuring the safety and reliability of the battery pack during operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A schematic flow chart of the steps of a method for modeling a thermal model of a battery pack; Figure 2 for Figure 1 Detailed implementation steps of step S1 in FIG. Figure 3 for Figure 1 Detailed implementation steps of step S4 in FIG. The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0025] The technical method of the present invention is described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by technicians in this field without creative work are within the scope of protection of the present invention.

[0026] In addition, the accompanying drawings are only schematic illustrations of the present invention and are not necessarily drawn to scale. The same reference numerals in the figures represent the same or similar parts, and their repeated description will be omitted. Some of the block diagrams shown in the accompanying drawings are functional entities and do not necessarily correspond to physically or logically independent entities. The functional entities can be implemented in software form, or implemented in one or more hardware modules or integrated circuits, or implemented in different networks and / or processor methods and / or microcontroller methods.

[0027] It should be understood that, although the terms "first", "second", etc. may be used herein to describe various units, these units should not be limited by these terms. These terms are used only to distinguish one unit from another unit. For example, without departing from the scope of the exemplary embodiments, the first unit may be referred to as the second unit, and similarly the second unit may be referred to as the first unit. The term "and / or" used herein includes any and all combinations of one or more of the listed associated items.

[0028] To achieve this, please refer to Figures 1 to 3, a method for modeling a battery pack thermal model, the method comprising the following steps: Step S1: determining the battery cell position inside the battery pack; identifying the cell topology structure at the battery cell position, and collecting the cell electrical temperature parameters at the battery cell position; Step S2: Calculate the electric temperature gradient difference of the electric temperature parameters of the cells to generate electric temperature difference data of the cells; perform a temperature field distribution detection on the cell topology structure of the cells using the electric temperature difference data of the cells, and draw a temperature distribution diagram of the cells; identify the thermal resistance flow path of the cells in the temperature distribution diagram of the cells; and construct an initial thermal model of the battery pack based on the cell topology structure and the thermal resistance flow path of the cells; Step S3: inputting the battery cell operating parameters into the initial thermal model of the battery pack, and performing a thermal energy state evaluation within the pack to obtain thermal energy state data of the battery pack; performing thermal imbalance region identification on the thermal energy state data of the battery pack to generate thermal imbalance region data; Step S4: marking the thermally unbalanced battery cells of the initial thermal model of the battery pack according to the thermally unbalanced region data, and performing regional heat dissipation optimization on the thermally unbalanced battery cells to obtain a thermal model of the battery pack.

[0029] By determining the position of the battery cells inside the battery pack, the present invention can clarify the specific layout of each cell in the battery pack, providing a basis for subsequent accurate modeling. By identifying the cell topology structure, the connection relationship between the battery cells can be fully understood, and the cell electrical temperature parameters of the battery cell position can be accurately collected. This process ensures the accuracy and comprehensiveness of the collected data, and provides reliable data support for subsequent operations such as electrical temperature gradient difference measurement and temperature field distribution detection, so that subsequent modeling can truly reflect the electrical temperature characteristics inside the battery pack; by measuring the electrical temperature gradient difference of the cell electrical temperature parameters, accurate cell electrical temperature difference data can be generated, thereby clearly presenting the unevenness of the electrical temperature distribution between the battery cells. The cell electrical temperature difference data is applied to the cell topology structure to perform cell temperature field distribution detection, and the cell temperature distribution diagram is drawn, which can intuitively display the temperature distribution inside the battery pack and help discover potential thermal management problems. Identifying the cell thermal resistance flow path of the cell temperature distribution diagram can clarify the heat conduction path in the battery pack, providing a key basis for building the initial thermal model of the battery pack. The initial thermal model of the battery pack constructed based on the monomer topology and the monomer thermal resistance flow path can more accurately reflect the thermal characteristics of the battery pack and provide a basis for the subsequent thermal energy state evaluation and optimization; the battery monomer operating parameters are input into the initial thermal model of the battery pack, and the thermal energy state evaluation is performed within the group. The obtained thermal energy state data of the battery pack can fully reflect the thermal energy distribution of the battery pack in actual operation. The thermal imbalance area is identified for the thermal energy state data of the battery pack. The generated thermal imbalance area data can accurately locate the area with thermal imbalance problems in the battery pack, provide a clear direction for the subsequent targeted heat dissipation optimization, and help improve the overall thermal management performance of the battery pack. According to the thermal imbalance area data, the thermal imbalance battery monomers of the initial thermal model of the battery pack are marked, and the regional heat dissipation optimization of the thermal imbalance battery monomers is performed. The final thermal model of the battery pack can more accurately reflect the actual thermal characteristics of the battery pack. Through this optimization, the temperature of the thermal imbalance area can be effectively reduced, the temperature difference inside the battery pack can be reduced, and the service life and safety of the battery pack can be improved. Therefore, the present invention uses data processing technology and simulation modeling technology to analyze the topological structure of battery cells and track the thermal resistance flow path in combination with the electrical and temperature parameters of the cells to construct a battery pack thermal model and fully present the thermal state of the battery pack, thereby improving the display accuracy of the battery pack thermal model; targeted battery pack heat dissipation optimization is performed based on the characteristics of the thermal imbalance area, which can effectively identify and solve the thermal imbalance problem and significantly improve the thermal management efficiency and performance stability of the battery pack.

[0030] In the embodiment of the present invention, reference Figure 1 FIG. 1 is a schematic diagram of a step flow of a method for modeling a thermal model of a battery pack according to the present invention. In this example, the method for modeling a thermal model of a battery pack includes the following steps: Step S1: determining the battery cell position inside the battery pack; identifying the cell topology structure at the battery cell position, and collecting the cell electrical temperature parameters at the battery cell position; In the embodiment of the present invention, it is first necessary to determine the position of the battery cell inside the battery pack, and use high-precision three-dimensional positioning technology. By arranging multiple positioning sensors inside the battery pack, combined with laser scanning or ultrasonic ranging technology, the three-dimensional coordinate position of each battery cell is accurately measured. The accuracy of the positioning sensor must reach the millimeter level to ensure the accuracy of the position information; identify the topological structure of the battery cell, and use the topological recognition technology based on the resistor network. By connecting a specific identification resistor in series in the battery pack, and collecting its voltage to the ground. Through the change of the voltage difference, combined with the preset mapping relationship between the voltage and the topological structure, the connection relationship between the battery cells is identified, and a complete topological structure is constructed; in terms of collecting the electrical and temperature parameters of the battery cell, a high-precision voltage sensor and temperature sensor are used. The voltage sensor adopts an isolated measurement solution with a range of 200V~1000V, an accuracy level of 0.05%, a linearity of 0.02%, and high stability and accuracy. The temperature sensor uses an NTC thermistor with a measurement range of -30℃ to 100℃ and an accuracy of ±0.5℃. The voltage sensor collects the voltage value of each battery cell with a sampling period of 10ms, and the temperature sensor records the temperature data with a sampling period of 100ms. The collected voltage and temperature data are transmitted to the data acquisition system through the CAN bus or Ethernet communication interface, and stored in the system with a storage frequency of 10ms. These data will serve as the basic input parameters for subsequent battery pack thermal modeling.

[0031] Step S2: Calculate the electric temperature gradient difference of the electric temperature parameters of the cells to generate electric temperature difference data of the cells; perform a temperature field distribution detection on the cell topology structure of the cells using the electric temperature difference data of the cells, and draw a temperature distribution diagram of the cells; identify the thermal resistance flow path of the cells in the temperature distribution diagram of the cells; and construct an initial thermal model of the battery pack based on the cell topology structure and the thermal resistance flow path of the cells; In an embodiment of the present invention, the collected single cell electrical temperature parameters are subjected to electrical temperature gradient difference measurement, and the specific operation is as follows: for each battery cell in the battery pack, the voltage difference (ΔV) between it and the adjacent cell is calculated. The voltage difference calculation formula is: ΔV=V_i-V_j, where V_i is the voltage value of the current cell, and V_j is the voltage value of the adjacent cell. The accuracy of the voltage sensor is 0.01V, and the sampling frequency is 10ms. Similarly, the temperature difference (ΔT) between each cell and the adjacent cell is calculated, and the temperature difference calculation formula is: ΔT=T_i-T_j, where T_i is the temperature value of the current cell, and T_j is the temperature value of the adjacent cell. The accuracy of the temperature sensor is ±0.5°C, and the sampling frequency is 10ms. The calculated voltage difference (ΔV) and temperature difference (ΔT) are stored in the data processing system. Next, based on the monomer electrical temperature difference data and the monomer topological structure, the monomer temperature field distribution is detected and the monomer temperature distribution diagram is drawn; the specific operation is as follows: According to the topological structure of the battery monomer, the heat conduction heat between each monomer and other monomers is calculated. The calculation formula is: Q=(k×ΔT×A) / d, where Q is the heat conduction heat, k is the thermal conductivity of the battery material (the value is 1.2W / (m·K)), ΔT is the temperature difference between the monomers, A is the contact area between the monomers (the value is 0.01m²), and d is the distance between the monomers (the value is 0.005m). The calculated heat conduction heat data is visualized and the monomer temperature distribution diagram of the battery pack is drawn. The temperature distribution diagram represents the temperature difference of different monomers in the form of color gradient, where the high temperature area is represented by red and the low temperature area is represented by blue. By analyzing the temperature gradient change in the monomer temperature distribution diagram, the monomer thermal resistance flow path is identified. The specific operation is as follows: In the temperature distribution diagram, the temperature gradient of each monomer is calculated. The calculation formula of temperature gradient is: ΔT / Δx, where ΔT is the temperature difference and Δx is the distance between cells. Areas with larger temperature gradients indicate paths with larger thermal resistance; based on the results of temperature gradient analysis, determine the heat transfer path within the battery pack. The determination of the thermal resistance flow path is based on the following parameters. The calculation formula of thermal resistance (R_th) is: R_th=d / (k×A), where d is the distance between cells (the value is 0.005m), k is the thermal conductivity (the value is 1.2W / (m·K)), and A is the contact area (the value is 0.01m²); by analyzing the direction of heat transfer from the high temperature area to the low temperature area in the temperature distribution diagram, the thermal resistance flow path is determined; based on the cell topology and the cell thermal resistance flow path, the initial thermal model of the battery pack is constructed. The specific operation is as follows: the battery pack is divided into several thermal resistors and thermal capacitance elements, and a thermal circuit model is established based on the cell topology and the thermal resistance flow path.The parameters of each component are set as follows: Heat capacity (C_th): Calculate the heat capacity according to the material and geometric dimensions of the battery cell, the formula is: C_th=m×c_p, where m is the mass of the cell (the value is 1.5kg), c_p is the specific heat (the value is 800J / (kg·K)), Thermal resistance (R_th): Calculate the thermal resistance according to the thermal resistance flow path, the formula is: R_th=d / (k×A), where d is the distance between the cells (the value is 0.005m), k is the thermal conductivity (the value is 1.2W / (m·K)), and A is the contact area (the value is 0.01m²); Set boundary conditions in the thermal model, such as the convection heat transfer coefficient (the value is 25W / (m²·K)) and the ambient temperature (the value is 25℃); Verify the accuracy of the initial thermal model by comparing the actual measured temperature data with the temperature data predicted by the model. If there is a deviation between the model prediction and the actual data, adjust the thermal resistance and heat capacity parameters until the model prediction is consistent with the actual data.

[0032] Step S3: inputting the battery cell operating parameters into the initial thermal model of the battery pack, and performing a thermal energy state evaluation within the pack to obtain thermal energy state data of the battery pack; performing thermal imbalance region identification on the thermal energy state data of the battery pack to generate thermal imbalance region data; In an embodiment of the present invention, the operating parameters of the battery cells are input into the initial thermal model of the battery pack. The operating parameters include the voltage, current, temperature, and charge and discharge rate of each battery cell. These parameters are collected in real time by high-precision sensors and transmitted to the data processing system at a sampling frequency of 10ms. The voltage and current data are used to calculate the power loss and heat generation rate of the battery, the temperature data is used to evaluate the thermal state of the battery, and the charge and discharge rate is set according to the actual operating conditions of the battery; next, the thermal energy state of the battery pack is evaluated based on the initial thermal model to obtain the thermal energy state data of the battery pack. The evaluation process adopts an electrochemical-thermal coupling model, which comprehensively considers the physical processes such as electrochemical reaction heat generation, heat conduction, convection heat transfer, and thermal radiation inside the battery. Through simulation calculation, the thermal energy state data such as temperature distribution, temperature difference and heat flow path of the battery pack under different operating conditions are obtained. The specific parameters are set as follows: the nominal capacity of the battery cell is 2.7Ah and the nominal voltage is 3.6V; in the electrochemical model, the equivalent resistance of the current collector is used to calculate the heat generation of the current collector, and the parameters of the electrode model are input according to the electrode size and material properties; in the thermal model, the total heat generation of the battery is calculated by the electrochemical model and coupled to the three-dimensional thermal model to calculate the temperature rise; then, the thermal imbalance area is identified for the thermal energy state data of the battery pack to generate thermal imbalance area data. By analyzing the temperature distribution map and temperature difference data, the area with abnormally high temperature, i.e., the thermal imbalance area, is identified. In the specific operation, the temperature gradient of each area inside the battery pack is calculated. When the temperature gradient exceeds the set threshold (such as 10℃ / cm), the area is determined to be a thermal imbalance area. In addition, by comparing the temperature changes at different rates, the area that is prone to thermal runaway under high-rate charge and discharge conditions can be identified; the identified thermal imbalance area data is stored in the data processing system to provide a basis for the subsequent battery pack thermal management strategy.

[0033] Step S4: marking the thermally unbalanced battery cells of the initial thermal model of the battery pack according to the thermally unbalanced region data, and performing regional heat dissipation optimization on the thermally unbalanced battery cells to obtain a thermal model of the battery pack.

[0034] In the embodiment of the present invention, the thermally unbalanced battery cell is first marked on the initial thermal model of the battery pack according to the thermally unbalanced area data. The specific operation is as follows: by analyzing the thermally unbalanced area data, the location of the battery cell with abnormally high temperature is determined, and these cells are marked in the initial thermal model; during the marking process, the temperature threshold of the thermally unbalanced area is set to be more than 20°C higher than the ambient temperature, which is used as the basis for identifying the thermally unbalanced cells; the thermally unbalanced battery cell is regionally optimized to obtain the optimized thermal model of the battery pack. The specific technical operations of the thermal optimization include the following aspects: for the thermally unbalanced area, the heat dissipation structure of the battery pack is adjusted. For example, the area of ​​the heat sink is increased or the layout of the heat sink is changed to improve the heat dissipation efficiency. The material of the heat sink is selected from aluminum alloy with high thermal conductivity, with a thickness of 2mm and a thermal conductivity of 200W / (m·K) to ensure efficient heat dissipation. By increasing the spacing between battery cells, air circulation is improved and heat accumulation is reduced. According to experimental data, the temperature of the thermally unbalanced area can be significantly reduced by optimizing the battery spacing from 5mm to 10mm. For the liquid cooling system, the flow rate of the coolant is adjusted according to the temperature distribution of the thermally unbalanced area. Experiments show that when the coolant flow rate increases from 5L / min to 15L / min, the maximum temperature of the battery pack can be reduced by 4°C. Therefore, the coolant flow rate is adjusted to 15L / min to optimize the heat dissipation effect. High thermal conductivity materials, such as graphene or thermally conductive silicone, are filled between battery cells in the thermal imbalance area to enhance heat conduction. The thermal conductivity of these materials can reach 1000W / (m·K), which can effectively reduce the local temperature.

[0035] As an example of the present invention, refer to Figure 2 As shown, in this example, step S1 includes: Step S11: spatially locating each battery cell inside the battery pack by using an electromagnetic induction positioning device, obtaining the coordinates of the battery cell inside the battery pack, and recording them as cell coordinate data; Step S12: determining the arrangement order and the cell spacing of the battery cells according to the cell coordinate data; encoding the position information of the battery cells based on the arrangement order and the cell spacing to obtain the battery cell position; Step S13: determining the connection relationship of adjacent battery cells according to the battery cell positions; identifying the cell topology of the battery cell connection relationship; Step S14: selecting a plurality of measuring points in the battery pack, wherein the measuring points are selected at three fixed positions of the positive electrode, the negative electrode, and the surface midpoint of the battery cell; Step S15: setting the parameters of the electrical temperature parameter acquisition device, including the voltage acquisition range of 0-5V, the current acquisition range of 0-10A, the temperature acquisition range of -20°C to 80°C, and the acquisition accuracy of 0.01V, 0.01A and 0.1°C respectively; Step S16: The first collection is performed at the first minute after the battery cell starts charging and discharging, the second collection is performed at the fifth minute, and the third collection is performed at the tenth minute, and each collection lasts for 1 second; Step S17: classify and store the voltage parameters, current parameters and temperature parameters to form single-cell electrical and temperature parameters.

[0036] In the embodiment of the present invention, each battery cell inside the battery pack is spatially positioned by an electromagnetic induction positioning device, the coordinates of the battery cell in the battery pack are obtained, and recorded as the cell coordinate data; the electromagnetic induction positioning device adopts a high-precision three-dimensional positioning sensor, and its positioning accuracy reaches 0.1mm, which can accurately measure the three-dimensional coordinate position of each battery cell; the arrangement order and the cell spacing of the battery cell are determined according to the cell coordinate data, the cell spacing is determined by calculating the coordinate difference between adjacent cells, and the position information of the battery cell is encoded based on the arrangement order. The encoding rule is to number the cells according to the arrangement order of the cells in the battery pack, and record the coordinate information of each cell at the same time; determine the connection relationship of adjacent battery cells according to the battery cell position, and identify the cell topology of the battery cell connection relationship. By analyzing the connection mode between the cells (such as series or parallel connection), a cell topology diagram is constructed, the connection relationship of each cell is clarified, and multiple measurement points in the battery pack are selected, and the measurement points are located at three fixed positions of the positive electrode, negative electrode and surface midpoint of the battery cell. These measurement points are used for subsequent electrical and temperature parameter collection to ensure that the thermal state of the battery cell can be fully reflected; the parameters of the electrical and temperature parameter collection equipment are set, the voltage collection range is 0-5V, the current collection range is 0-10A, the temperature collection range is -20℃ to 80℃, and the collection accuracy is 0.01V, 0.01A and 0.1℃ respectively; the electrical and temperature parameters are collected, the first collection is carried out in the first minute after the battery cell starts charging and discharging, the second collection is carried out in the fifth minute, and the third collection is carried out in the tenth minute, and each collection lasts for 1 second. During the collection process, the voltage, current and temperature data are transmitted to the data processing system in real time through high-precision sensors, and the collected voltage parameters, current parameters and temperature parameters are classified and stored. The voltage data is stored as a voltage parameter file, the current data is stored as a current parameter file, and the temperature data is stored as a temperature parameter file to form a single-cell electrical and temperature parameter data set.

[0037] Preferably, the step S2 of calculating the difference in electrical temperature gradient of the electrical temperature parameters of the monomer includes: Marking the battery cell measurement points of the battery cell electrical temperature parameters, determining the positive and negative electrode areas of the battery according to the battery cell measurement points, and determining the body center area of ​​the battery cell surface based on the positive and negative electrode areas of the battery; The temperature difference between the positive and negative regions of the battery is calculated to obtain the temperature difference between the positive and negative regions; the voltage difference between the positive and negative regions of the battery is calculated to obtain the voltage difference between the positive and negative regions; the current difference between the positive and negative regions of the battery is calculated to obtain the current difference between the positive and negative regions; Extract the temperature value, voltage value and current value of the center area of ​​the battery cell surface; The temperature difference between the positive and negative electrodes, the voltage difference between the positive and negative electrodes, and the current difference between the positive and negative electrodes are numerically compared with the temperature value, voltage value, and current value of the body center area, respectively, and arranged according to the numerical gradient to obtain the electrical temperature gradient difference data.

[0038] In the embodiment of the present invention, Mark the battery cell measurement points for the single cell electrical and temperature parameters, and use high-precision sensors to arrange measurement points at the positive, negative and surface midpoint positions of the battery cell to collect voltage, current and temperature data; determine the positive and negative electrode areas of the battery based on the location information of the measurement points, where the positive electrode area corresponds to the positive electrode measurement point and the negative electrode area corresponds to the negative electrode measurement point. Based on the positive and negative electrode areas, further determine the body center area of ​​the battery cell surface, that is, the area where the surface midpoint measurement point is located; The temperature difference, voltage difference and current difference of the positive and negative regions of the battery are calculated. The specific operations are as follows: read the temperature values ​​of the positive and negative measurement points respectively, and calculate the temperature difference (ΔT) of the positive and negative electrodes. The formula is: ΔT=T_positive-T_negative; read the voltage values ​​of the positive and negative measurement points, and calculate the voltage difference (ΔV) of the positive and negative electrodes. The formula is: ΔV=V_positive-V_negative; read the current values ​​of the positive and negative measurement points, and calculate the current difference (ΔI) of the positive and negative electrodes. The formula is: ΔI=I_positive-I_negative; extract the temperature value (T_body center), voltage value (V_body center) and current value (I_body center) of the body center area of ​​the battery cell surface. These data are collected through the midpoint measurement point of the surface; compare the temperature difference, voltage difference and current difference of the positive and negative electrodes with the corresponding parameters of the body center area, and arrange them according to the numerical gradient to obtain the electric temperature gradient difference data. The specific operation is: calculate the ratio of ΔT to T_body center to obtain the temperature gradient difference. Calculate the ratio of ΔV to V_body center to get the voltage gradient difference. Calculate the ratio of ΔI to I_body center to get the current gradient difference.

[0039] Preferably, the step S2 of performing a temperature field distribution test on the topological structure of the monomer using the monomer electrical temperature difference data and drawing a monomer temperature distribution diagram comprises: The temperature difference data of the single cell is processed in time series, and the temperature change rate of each single cell at different time points is calculated to obtain the temperature change rate of the single cell; According to the monomer topological structure, determine whether the single battery is at the edge or the middle position, and obtain the battery position data; Determine the arrangement of the cell topology and classify the arrangement into series cells and parallel cells; Based on the battery location data, the series batteries and parallel batteries are used to calculate the heat dissipation space of the single battery to obtain the heat dissipation space data of the single battery; Determine the local temperature data of the single cell according to the heat dissipation space data of the single cell; Conduct temperature field statistics on the local temperature data of the monomer and detect the heat distribution data of the temperature field; Import the temperature field heat distribution data into the drawing tool, and map the data points into a two-dimensional coordinate system according to the temperature gradient, where the coordinate axes represent the physical position and temperature value of the battery pack, respectively, to obtain a single cell temperature distribution diagram.

[0040] In an embodiment of the present invention, the electric temperature difference data of the monomer is processed in time series, and the electric temperature change rate of each monomer battery at different time points is calculated to obtain the electric temperature change rate of the monomer battery. In the specific operation, the collected monomer electric temperature parameters are arranged in time order, and the voltage, current and temperature change rates at adjacent time points are calculated. For example, for the voltage change rate (ΔV / Δt), the current change rate (ΔI / Δt) and the temperature change rate (ΔT / Δt), the following formulas are used to calculate: ΔV / Δt=(V_t2-V_t1) / Δt, ΔI / Δt=(I_t2-I_t1) / Δt, ΔT / Δt=(T_t2-T_t1) / Δt, where V_t1, I_t1, T_t1 are the voltage, current and temperature values ​​at the initial time point, V_t2, I_t2, T_t2 are the corresponding values ​​at subsequent time points, and Δt is the time interval; according to the monomer topology structure, it is judged whether the monomer battery is at the edge and the middle position to obtain the battery position data. By analyzing the arrangement of the battery pack, the position of each single cell in the battery pack is identified. The edge battery is defined as a single cell in direct contact with the external environment, and the middle battery is a single cell surrounded by other single cells; the arrangement of the single cell topology is further determined, and the arrangement is divided into series batteries and parallel batteries. By analyzing the connection relationship of the battery pack, the single cells connected in series and in parallel are identified. The voltage of the series battery is accumulated, and the current is consistent; the current of the parallel battery is accumulated, and the voltage is consistent; based on the battery location data, the heat dissipation space of the single cell is calculated for the series battery and the parallel battery to obtain the heat dissipation space data of the single cell. For the edge battery, the heat dissipation space is larger and the heat dissipation coefficient is higher; for the middle battery, the heat dissipation space is limited and the heat dissipation coefficient is lower. The heat dissipation space calculation formula is: heat dissipation space = battery surface area × heat dissipation coefficient, where the heat dissipation coefficient is determined according to the battery position and the surrounding environment; according to the heat dissipation space data of the single cell, the local temperature data of the single cell is determined. The local temperature of each single cell is calculated based on the relationship between the heat dissipation space and the temperature. The calculation formula of local temperature is: local temperature = basic temperature + heat dissipation space × heat dissipation coefficient × heat flux density; the basic temperature is the ambient temperature, and the heat flux density is calculated according to the heat generation rate and heat dissipation coefficient of the battery; the local temperature data of the single cell is statistically analyzed in the temperature field, and the heat distribution data of the temperature field is detected. By statistically analyzing the local temperature of each single cell, a temperature field distribution diagram is drawn to analyze the distribution of heat in the battery pack. The temperature field heat distribution data is imported into the drawing tool, and the data points are mapped to a two-dimensional coordinate system according to the temperature gradient, where the coordinate axes represent the physical position and temperature value of the battery pack, respectively, to obtain the temperature distribution diagram of the single cell. The drawing tool uses professional software (such as MATLAB or ANSYS) to convert the temperature data points into a temperature distribution diagram through interpolation and fitting algorithms, and intuitively display the temperature distribution inside the battery pack.

[0041] It is particularly important that the temperature field statistics of the local temperature data of the monomer and the detection of the heat distribution data of the temperature field include: Dividing the local temperature data of the single cell into temperature range segments, determining a plurality of sub-regions of the temperature range segments, each sub-region containing at least 3 single cells; The temperature data in each sub-area is weighted averaged, where the weight range of the central area is 0.5 to 0.7, and the weight range of the edge area is 0.3-0.5; Perform temperature field statistics on the temperature data of each sub-area and calculate the temperature fluctuation coefficient of each sub-area; A heat flow sensor is provided in each sub-area, wherein the accuracy range of the heat flow sensor is ±0.005W / m² to ±0.02W / m², and the heat inflow and outflow data of each sub-area are collected; and the heat balance coefficient of each sub-area is calculated; The temperature thermal field distribution is determined based on the temperature fluctuation coefficient and the heat balance coefficient to obtain the temperature field heat distribution data.

[0042] In an embodiment of the present invention, first, the local temperature data of the single cell is divided into temperature range segments, and multiple sub-areas of the temperature range segment are determined, each sub-area containing at least 3 single cells. By analyzing the temperature data of the single cells in the battery pack, the temperature range is divided into several segments, for example, each 5°C is a temperature segment, and the sub-areas are divided according to the temperature segments. Then, the temperature data in each sub-area is weighted averaged, wherein the weight range of the central area is 0.5 to 0.7, and the weight range of the edge area is 0.3 to 0.5. The specific operation is: in each sub-area, weights are assigned according to the position of the battery cell, the weight of the single cell in the central area is 0.6, and the weight of the single cell in the edge area is 0.4, and the weighted average temperature is calculated. Then, the temperature field statistics of the temperature data of each sub-area are performed, and the temperature fluctuation coefficient of each sub-area is calculated. The temperature fluctuation coefficient is determined by calculating the ratio of the standard deviation of the temperature data in the sub-area to the average temperature, and the formula is: temperature fluctuation coefficient = (temperature standard deviation) / (weighted average temperature). A heat flow sensor with an accuracy range of ±0.005W / m² to ±0.02W / m² is set in each sub-area to collect heat inflow and outflow data of each sub-area. The heat flow sensor is installed at the boundary of the sub-area to monitor the flow of heat in real time. According to the collected heat inflow and outflow data, the heat balance coefficient of each sub-area is calculated, and the formula is: heat balance coefficient = (heat inflow-heat outflow) / (heat inflow+heat outflow). Finally, the temperature thermal field distribution is determined based on the temperature fluctuation coefficient and the heat balance coefficient to obtain the temperature field heat distribution data. By comprehensively analyzing the temperature fluctuation coefficient and the heat balance coefficient, the thermal field distribution of each sub-area is evaluated, and the results are recorded as the temperature field heat distribution data.

[0043] Preferably, the monomer thermal resistance flow path of the monomer temperature distribution diagram identified in step S2 includes: The monomer temperature distribution map is divided into regions according to the temperature range, and the temperature range of each region is set to 5°C; In each temperature gradient region, the temperature difference between adjacent single cells is measured, and the ratio of the temperature difference to the distance between adjacent single cells is calculated to obtain temperature-distance difference ratio data; If the temperature-distance difference ratio data is greater than 0.3°C / cm, it is preliminarily determined that the single cell corresponding to the temperature-distance difference ratio data is the starting point of the thermal resistance flow path; Determine the direction of the thermal resistance flow path based on the starting point of the thermal resistance flow path; if the single cells are connected in parallel, the direction of the thermal resistance flow path is perpendicular to the current flow direction; if the single cells are connected in series, the direction of the thermal resistance flow path is along the current flow direction; The intensity of the thermal resistance flow path is determined by comparing the temperature difference between the temperature gradient regions. The greater the temperature difference between the temperature gradient regions, the higher the intensity of the thermal resistance flow path. The direction and intensity of the thermal resistance flow path are marked on the monomer temperature distribution diagram with red lines, and the marked thermal resistance flow path is superimposed on the monomer temperature distribution diagram to form the monomer thermal resistance flow path.

[0044] In an embodiment of the present invention, the monomer temperature distribution diagram is divided into regions according to the temperature range, and the temperature range of each region is set to 5°C. By analyzing the monomer temperature distribution diagram, the temperature data is divided into several temperature gradient regions at intervals of 5°C. For example, the temperature range from 20°C to 40°C is divided into four regions of 20-25°C, 25-30°C, 30-35°C and 35-40°C; in each temperature gradient region, the temperature difference between adjacent monomer batteries is measured, and the ratio of the temperature difference to the distance between adjacent monomer batteries is calculated to obtain the temperature-distance difference ratio data. In the specific operation, a high-precision temperature sensor is used to measure the temperature difference (ΔT) between adjacent monomer batteries, and the temperature-distance difference ratio (ΔT / d) is calculated in combination with the actual distance (d) between the monomer batteries, with the unit of °C / cm; if the temperature-distance difference ratio data is greater than 0.3°C / cm, it is preliminarily determined that the monomer battery corresponding to the temperature-distance difference ratio data is the starting point of the thermal resistance flow path. By comparing the calculated temperature-distance difference ratio data, the single cells with a value greater than 0.3°C / cm are screened out and marked as the starting point of the thermal resistance flow path; the direction of the thermal resistance flow path is determined based on the starting point of the thermal resistance flow path. If the single cells are connected in parallel, the direction of the thermal resistance flow path is perpendicular to the current flow direction; if the single cells are connected in series, the direction of the thermal resistance flow path is along the current flow direction. By analyzing the topological structure of the battery pack, the connection mode of the single cells is identified, and the direction of the thermal resistance flow path is determined accordingly; the temperature difference between the temperature gradient regions is compared to determine the strength of the thermal resistance flow path. The greater the temperature difference between the temperature gradient regions, the higher the strength of the thermal resistance flow path. The strength of the thermal resistance flow path is evaluated by calculating the temperature difference between adjacent temperature gradient regions. The greater the temperature difference, the higher the strength of the thermal resistance flow path; the direction and strength of the thermal resistance flow path are marked on the single temperature distribution map with red lines, and the marked thermal resistance flow path is superimposed on the single temperature distribution map to form a single thermal resistance flow path. Use a drawing tool (such as Origin or Tecplot) to plot the direction and intensity of the thermal resistance flow path as a red line on the monomer temperature distribution diagram to complete the visualization of the thermal resistance flow path.

[0045] Preferably, the step S2 of constructing the initial thermal model of the battery pack based on the cell topology and the cell thermal resistance flow path includes: Convert the cell topology and the cell thermal resistance flow path into a battery cell file, and import the battery cell file into Solidworks software; Set the single cell as a thermal network node according to the single cell topology, determine the arrangement, connection structure and battery layout of the single cell, and mark the position and size of each single cell; The thermal resistance flow path is set as the connecting edge between the thermal network nodes, and the thermal resistance parameters between the nodes are set; Connect the thermal resistance flow paths of adjacent single cells; if they are series cells, the current directions are connected sequentially; if they are parallel cells, the current directions are connected perpendicular to the parallel currents; The Solidworks simulation function is started to build an initial thermal model of the battery pack.

[0046] In an embodiment of the present invention, the monomer topology and the monomer thermal resistance flow path are converted into a battery monomer file. The specific operation is: according to the monomer topology and thermal resistance flow path of the battery pack, a file containing the position, size, connection relationship and thermal resistance parameters of the monomer battery is generated. The file can be in a general format supported by Solidworks, such as STEP or IGES file; the battery monomer file is imported into the Solidworks software. Open Solidworks, select "Open" from the "File" menu, browse and select the generated battery monomer file (such as STEP or IGES format), and click "Open" to complete the import. During the import process, make sure to select the correct file format and select the appropriate template (such as a part or assembly template) when prompted; according to the monomer topology, the monomer battery is set as a thermal network node, and the arrangement, connection structure and battery layout of the monomer battery are determined. In Solidworks, each monomer battery model is inserted into the assembly through the "Insert Component" function, and its position and direction are adjusted according to the topological structure. Mark the position and size of each single cell to ensure that it is consistent with the actual battery pack design; set the thermal resistance flow path as the connection edge between the thermal network nodes, and define the heat transfer path by setting the thermal resistance parameters between the nodes. In Solidworks, use the "Assembly" function to add the thermal resistance flow path between the single cells in the form of a virtual connector, and specify the thermal resistance parameters for each connection edge; connect the thermal resistance flow paths of adjacent single cells. For series batteries, the current direction is connected in sequence; for parallel batteries, the current direction is connected perpendicular to the parallel current. In Solidworks, adjust the direction and position of the connection edge to ensure that it complies with the connection rules of series or parallel; start the simulation function of Solidworks software to build the initial thermal model of the battery pack. Enter the FlowSimulation module of Solidworks and set the simulation parameters, including the initial temperature of the battery pack, ambient temperature, heat source power, material properties (such as thermal conductivity, specific heat capacity), and boundary conditions. Run the simulation, observe the temperature distribution and heat transfer path of the battery pack, generate a single cell temperature distribution diagram, and mark the direction and intensity of the thermal resistance flow path.

[0047] Preferably, the step S3 of inputting the battery cell operating parameters into the initial thermal model of the battery pack and evaluating the thermal energy state within the pack includes: Inputting the battery cell operating parameters into the initial thermal model of the battery pack; Set the initial conditions of the battery cell temperature, and set the initial temperature to 25°C and the coolant temperature to 20°C; Set the battery cell operation mode to intermittent charge and discharge, and set the charge and discharge current to 1A and the charge and discharge voltage to 5V; Continuously monitor the temperature values ​​of the middle battery and the batteries on both sides of the group, and calculate the temperature difference between the temperature values ​​of the middle battery and the batteries on both sides of the group to obtain the temperature aggregation data within the group; Mark the temperature aggregation space of the temperature aggregation data within the group, and divide the temperature aggregation space into temperature aggregation points; The thermal energy parameters around the temperature gathering point are monitored incrementally with a circle of 0.1 cm radius to obtain the thermal energy diffusion data within the group; The thermal energy diffusion data within the group is subjected to diffusion gradient identification, and the thermal energy state of the diffusion gradient is evaluated to obtain the thermal energy state data of the battery group.

[0048] In an embodiment of the present invention, the operating parameters of the battery cell are input into the initial thermal model of the battery pack. The operating parameters include charge and discharge current, voltage, initial temperature, etc. The specific operation is: in the simulation software (such as ANSYS or SolidworksSimulation), set the initial temperature of the battery cell to 25°C and the coolant temperature to 20°C. At the same time, set the battery cell operation mode to intermittent charge and discharge, the charge and discharge current to 1A, and the charge and discharge voltage to 5V; next, continuously monitor the temperature values ​​of the middle battery in the group and the batteries on both sides of the group. By setting the temperature monitoring point in the simulation model, the temperature changes of the middle battery and the batteries on both sides are recorded in real time. The temperature difference between the temperature value of the middle battery in the group and the temperature value of the batteries on both sides of the group is calculated to obtain the temperature aggregation data in the group. The specific operation is: in the simulation software, use the temperature field analysis function to calculate the temperature difference between the middle battery and the batteries on both sides; mark the temperature aggregation space of the temperature aggregation data in the group, and divide the temperature aggregation space into temperature aggregation points. Through the temperature field cloud map analysis, the temperature concentration area is identified, and the thermal energy parameters around the temperature concentration point are monitored incrementally with a circle with a radius of 0.1 cm; further, the thermal energy diffusion data within the group is identified by diffusion gradient, and the thermal energy state of the diffusion gradient is evaluated to obtain the thermal energy state data of the battery pack. The specific operation is: in the simulation software, the thermal flow analysis function is used to calculate the thermal energy diffusion gradient and evaluate the thermal energy state of the battery pack. By analyzing the distribution law of the temperature field and the temperature difference change, it is determined whether the thermal energy state of the battery pack is within a reasonable range.

[0049] Preferably, the step S3 of identifying the thermal imbalance area of ​​the battery pack thermal energy status data includes: Calculate the average temperature of the single cells in the battery pack according to the thermal energy status data of the battery pack; The difference between the temperature of each single battery and the average temperature is counted. When the difference exceeds 2°C, the battery is marked as a temperature abnormal point. If there are more than three temperature anomaly points in an area, and the temperature anomaly points are connected to each other, the area is determined to be a potential thermal imbalance area; Conduct voltage and current detection on cells in potential thermal imbalance areas, and set the voltage threshold to ±10% of the rated voltage of the cell, and the current threshold to ±20% of the rated current; When the voltage or current of a single cell exceeds the corresponding threshold, it is recorded as an abnormal state; if a single cell has abnormal temperature, abnormal voltage and abnormal current at the same time, it is determined that the battery cell has thermal runaway, and the potential thermal imbalance area where the battery cell is located is determined as the thermal imbalance area and recorded as thermal imbalance area data.

[0050] In an embodiment of the present invention, the average temperature of the single cells in the battery pack is calculated according to the thermal energy state data of the battery pack. The temperature data of all the single cells in the battery pack are collected, and the arithmetic mean thereof is calculated to obtain the average temperature of the battery pack. The specific operation is: the temperature values ​​of all the single cells are accumulated and divided by the total number of single cells; then, the difference between the temperature of each single cell and the average temperature is counted. When the difference exceeds 2°C, the battery is marked as a temperature abnormal point. The specific operation is: the difference between the temperature of each single cell and the average temperature is calculated one by one, and the single cells with a difference greater than 2°C are screened out; if there are more than 3 temperature abnormal points in an area, and these temperature abnormal points are connected to each other, the area is determined to be a potential thermal imbalance area. By analyzing the spatial distribution of the temperature abnormal points, the area that meets the conditions is identified; the voltage and current of the single cells in the potential thermal imbalance area are detected. The voltage threshold is set to ±10% of the rated voltage of the single cell, and the current threshold is set to ±20% of the rated current. The specific operation is: using high-precision voltage and current sensors (such as INA226) to measure the voltage and current of the single cells in the potential thermal imbalance area respectively, and compare them with the set thresholds. For example, for a battery with a rated voltage of 3.7V and a rated current of 1A, the voltage threshold range is 3.33V~4.07V, and the current threshold range is 0.8A~1.2A; when the voltage or current of a single battery exceeds the corresponding threshold, it is recorded as an abnormal state; if a single battery has abnormal temperature, abnormal voltage and abnormal current at the same time, it is determined that the battery cell has thermal runaway, and the potential thermal imbalance area where the battery cell is located is determined as a thermal imbalance area, and recorded as thermal imbalance area data.

[0051] As an example of the present invention, refer to Figure 3 As shown, in this example, step S4 includes: Step S41: dividing the thermal imbalance area data into a high-risk area, a medium-risk area and a normal area to determine the thermal imbalance division area; Step S42: color-marking the initial thermal model of the battery pack according to the thermal imbalance division area, wherein red indicates a high-risk area, yellow indicates a medium-risk area, and green indicates a normal area; determining the thermally unbalanced battery cell according to the model color marking information; Step S43: increasing the cooling wind speed of the area of ​​the thermally unbalanced battery cell and reducing the number of charge and discharge times to obtain optimized parameters of the thermally unbalanced battery; Step S44: transmitting the thermally unbalanced battery optimization parameters back to the initial thermal model of the battery pack to obtain the thermal model of the battery pack.

[0052] In an embodiment of the present invention, the thermal imbalance area data is divided into high-risk areas, medium-risk areas and normal areas to determine the thermal imbalance division areas. The specific operation is: according to the temperature abnormality degree, voltage and current abnormality of the single battery in the battery pack, combined with the pre-set threshold, the thermal imbalance area is classified. For example, when the temperature abnormality of the single battery exceeds 5°C, the voltage abnormality exceeds ±15% of the rated voltage, or the current abnormality exceeds ±30% of the rated current, it is divided into a high-risk area; when the temperature abnormality is between 3°C and 5°C, the voltage abnormality is between ±10% and ±15% of the rated voltage, or the current abnormality is between ±20% and ±30% of the rated current, it is divided into a medium-risk area; the rest of the cases are divided into normal areas; the initial thermal model of the battery pack is color-coded according to the thermal imbalance division area, where red indicates a high-risk area, yellow indicates a medium-risk area, and green indicates a normal area. The specific operation is: in the thermal model of the battery pack, according to the division results of each area, use the color coding tool to mark the corresponding area. Through the color mapping function of visualization software (such as ANSYS or SolidworksSimulation), high-risk areas are marked as red, medium-risk areas are marked as yellow, and normal areas are marked as green. According to the model color marking information, the thermally unbalanced battery cells, that is, the battery cells in the area marked as red or yellow, are determined; the cooling wind speed in the area of ​​thermally unbalanced battery cells is increased, and the number of charge and discharge times is reduced to obtain the thermally unbalanced battery optimization parameters. The specific operation is: for the battery cell area marked as thermally unbalanced, the cooling system parameters are adjusted to increase the cooling wind speed from the initial value (such as 5m / s) to the optimized value (such as 8m / s). At the same time, the battery charge and discharge strategy is adjusted to reduce the number of charge and discharge times from the initial setting value (such as 5 times a day) to the optimized value (such as 3 times a day). The adjustment of these optimization parameters is aimed at reducing the temperature of the thermally unbalanced area and reducing the heat generation of the battery during the charge and discharge process, thereby alleviating the thermal imbalance phenomenon; the thermally unbalanced battery optimization parameters are transmitted back to the initial thermal model of the battery pack to obtain the battery pack thermal model. The specific operation is: input the adjusted cooling wind speed and charge and discharge times and other optimization parameters into the battery pack thermal model, update the relevant parameter settings of the model. By re-running the thermal model simulation, verify the effectiveness of the optimization parameters to ensure that the model can accurately reflect the thermal state of the battery pack after optimization.

[0053] It is particularly important that step S43 includes the following steps: Step S431: performing regional imbalance state judgment on the thermally unbalanced battery cells to obtain imbalance state data; Step S432: quantifying the urgency of the imbalance state data to generate imbalance urgency data; Step S433: sorting the thermally unbalanced battery cells by cell imbalance priority based on the imbalance urgency data to obtain cell imbalance priority data; Step S434: determining the regional cooling wind speed parameter according to the imbalance severity data, and determining the number of charge and discharge times according to the imbalance state data; Step S435: matching cooling measures for thermally unbalanced battery cells through cell imbalance priority data, and optimizing thermal imbalance for thermally unbalanced battery cells based on regional cooling wind speed parameters and charge and discharge times to obtain thermally unbalanced battery optimization parameters.

[0054] In an embodiment of the present invention, a regional imbalance state judgment is performed on a thermally unbalanced battery cell to obtain imbalance state data. By monitoring the temperature, voltage and current changes of the battery cell, its imbalance state is judged in combination with a preset threshold. For example, when the temperature abnormality of the single cell exceeds 5°C, the voltage abnormality exceeds ±15% of the rated voltage, or the current abnormality exceeds ±30% of the rated current, the battery cell is judged to be in a high imbalance state; when the temperature abnormality is between 3°C and 5°C, the voltage abnormality is between ±10% and ±15% of the rated voltage, or the current abnormality is between ±20% and ±30% of the rated current, it is judged to be a medium imbalance state; the rest of the cases are low imbalance states; the imbalance state data is quantified for urgency, and imbalance urgency data is generated. According to the severity of the imbalance state, the urgency is divided into three levels: high, medium and low. The specific quantification standard is: the urgency corresponding to the high imbalance state is high (the value is 3), the urgency corresponding to the medium imbalance state is medium (the value is 2), and the urgency corresponding to the low imbalance state is low (the value is 1). The imbalance urgency data is obtained by calculating the urgency value of each battery cell. Based on the imbalance urgency data, the thermally unbalanced battery cells are prioritized for imbalance, and the imbalance priority data is obtained. The battery cells are sorted according to the urgency value. The higher the urgency value, the higher the priority. For example, the battery cell with an urgency of 3 has the highest priority, followed by the urgency of 2, and the urgency of 1 has the lowest priority. The sorting result is used as the monomer imbalance priority data for subsequent optimization measures allocation. The regional cooling wind speed parameters are determined according to the imbalance urgency data, and the number of charge and discharge times is determined according to the imbalance state data. For battery cells in a high imbalance state, the cooling wind speed is increased to 8m / s, and the number of charge and discharge times is reduced to 2 times a day; for battery cells in a medium imbalance state, the cooling wind speed is increased to 6m / s, and the number of charge and discharge times is reduced to 3 times a day; for battery cells in a low imbalance state, the cooling wind speed is increased to 4m / s, and the number of charge and discharge times remains unchanged. The thermal imbalance battery cells are matched with cooling measures through the cell imbalance priority data, and the thermal imbalance of the thermal imbalance battery cells is optimized based on the regional cooling wind speed parameters and the number of charge and discharge times to obtain the thermal imbalance battery optimization parameters. According to the priority sorting results, cooling measures are implemented for the high-priority battery cells in turn, including adjusting the cooling wind speed and charge and discharge strategies. The optimized parameters are used as the thermal imbalance battery optimization parameters for subsequent battery pack thermal management.

[0055] The present specification also provides a battery pack thermal model modeling system, which is used to execute the battery pack thermal modeling method as described above. The battery pack thermal model modeling system includes: The cell electrical temperature parameter acquisition module is used to determine the battery cell position inside the battery pack; identify the cell topology structure of the battery cell position, and collect the cell electrical temperature parameters of the battery cell position; The module for constructing the initial thermal model of the battery pack is used to measure the difference in the electrical temperature gradient of the electrical temperature parameters of the cells and generate the data of the electrical temperature difference of the cells; to detect the distribution of the temperature field of the cells on the topological structure of the cells using the electrical temperature difference data of the cells and draw the temperature distribution diagram of the cells; to identify the thermal resistance flow path of the cells in the temperature distribution diagram of the cells; and to construct the initial thermal model of the battery pack based on the topological structure of the cells and the thermal resistance flow path of the cells; The thermal state region detection module is used to input the battery cell operating parameters into the initial thermal model of the battery pack, and to evaluate the thermal energy state within the pack to obtain the thermal energy state data of the battery pack; to identify the thermal imbalance region of the thermal energy state data of the battery pack to generate the thermal imbalance region data; The thermal imbalance identification and optimization module is used to mark the thermally unbalanced battery cells in the initial thermal model of the battery pack according to the thermal imbalance area data, and to perform regional heat dissipation optimization on the thermally unbalanced battery cells to obtain the thermal model of the battery pack.

[0056] The present invention realizes accurate modeling and dynamic optimization of the temperature distribution inside the battery pack through the synergistic effects of single-cell electrical temperature parameter collection, initial thermal model construction, thermal state area detection, and thermal imbalance identification and optimization. It can accurately identify the thermal imbalance area and perform targeted heat dissipation optimization, thereby improving the thermal stability of the battery pack, optimizing the thermal management effect of the battery pack, extending the battery life, and ensuring the safety and reliability of the battery pack during operation.

[0057] Therefore, the embodiments should be regarded as illustrative and non-restrictive from all points, and the scope of the present invention is limited by the appended claims rather than the above description, and it is therefore intended that all changes falling within the meaning and range of equivalent elements of the application documents are included in the present invention.

[0058] The above description is only a specific embodiment of the present invention, so that those skilled in the art can understand or implement the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but should conform to the widest scope consistent with the principles and novel features invented herein.

Claims

1. A method for modeling a battery pack thermal model, characterized in that: The following steps are involved: Step S1: determining the battery cell position inside the battery pack; identifying the cell topology structure at the battery cell position, and collecting the cell electrical temperature parameters at the battery cell position; Step S2: Calculate the electric temperature gradient difference of the electric temperature parameters of the cells to generate electric temperature difference data of the cells; perform a temperature field distribution detection on the cell topology structure of the cells using the electric temperature difference data of the cells, and draw a temperature distribution diagram of the cells; identify the thermal resistance flow path of the cells in the temperature distribution diagram of the cells; and construct an initial thermal model of the battery pack based on the cell topology structure and the thermal resistance flow path of the cells; Step S3: inputting the battery cell operating parameters into the initial thermal model of the battery pack, and evaluating the thermal energy state within the pack to obtain the thermal energy state data of the battery pack; Identify thermal imbalance areas on the thermal energy status data of the battery pack and generate thermal imbalance area data; Step S4: marking the thermally unbalanced battery cells of the initial thermal model of the battery pack according to the thermally unbalanced region data, and performing regional heat dissipation optimization on the thermally unbalanced battery cells to obtain a thermal model of the battery pack.

2. The method for modeling a battery pack thermal model according to claim 1, characterized in that: Step S1 includes the following steps: Step S11: spatially locating each battery cell inside the battery pack by using an electromagnetic induction positioning device, obtaining the coordinates of the battery cell inside the battery pack, and recording them as cell coordinate data; Step S12: determining the arrangement order and the cell spacing of the battery cells according to the cell coordinate data; encoding the position information of the battery cells based on the arrangement order and the cell spacing to obtain the battery cell position; Step S13: determining the connection relationship of adjacent battery cells according to the battery cell positions; identifying the cell topology of the battery cell connection relationship; Step S14: selecting a plurality of measuring points in the battery pack, wherein the measuring points are selected at three fixed positions of the positive electrode, the negative electrode, and the surface midpoint of the battery cell; Step S15: setting the parameters of the electrical temperature parameter acquisition device, including the voltage acquisition range of 0-5V, the current acquisition range of 0-10A, the temperature acquisition range of -20°C to 80°C, and the acquisition accuracy of 0.01V, 0.01A and 0.1°C respectively; Step S16: The first collection is performed at the first minute after the battery cell starts charging and discharging, the second collection is performed at the fifth minute, and the third collection is performed at the tenth minute, and each collection lasts for 1 second; Step S17: classify and store the voltage parameters, current parameters and temperature parameters to form single-cell electrical and temperature parameters.

3. The method for modeling a battery pack thermal model according to claim 1, characterized in that: The step S2 of calculating the difference in electrical temperature gradient of the electrical temperature parameters of the monomer includes: Marking the battery cell measurement points of the battery cell electrical temperature parameters, determining the positive and negative electrode areas of the battery according to the battery cell measurement points, and determining the body center area of ​​the battery cell surface based on the positive and negative electrode areas of the battery; The temperature difference between the positive and negative regions of the battery is calculated to obtain the temperature difference between the positive and negative regions; the voltage difference between the positive and negative regions of the battery is calculated to obtain the voltage difference between the positive and negative regions; the current difference between the positive and negative regions of the battery is calculated to obtain the current difference between the positive and negative regions; Extract the temperature value, voltage value and current value of the center area of ​​the battery cell surface; The temperature difference between the positive and negative electrodes, the voltage difference between the positive and negative electrodes, and the current difference between the positive and negative electrodes are numerically compared with the temperature value, voltage value, and current value of the body center area, respectively, and arranged according to the numerical gradient to obtain the electrical temperature gradient difference data.

4. The method for modeling a battery pack thermal model according to claim 1, characterized in that: The step S2 of using the cell electrical temperature difference data to detect the cell temperature field distribution of the cell topology structure and drawing a cell temperature distribution diagram includes: The temperature difference data of the single cell is processed in time series, and the temperature change rate of each single cell at different time points is calculated to obtain the temperature change rate of the single cell; According to the monomer topological structure, determine whether the single battery is at the edge or the middle position, and obtain the battery position data; Determine the arrangement of the cell topology and classify the arrangement into series cells and parallel cells; Based on the battery location data, the series batteries and parallel batteries are used to calculate the heat dissipation space of the single battery to obtain the heat dissipation space data of the single battery; Determine the local temperature data of the single cell according to the heat dissipation space data of the single cell; Conduct temperature field statistics on the local temperature data of the monomer and detect the heat distribution data of the temperature field; Import the temperature field heat distribution data into the drawing tool, and map the data points into a two-dimensional coordinate system according to the temperature gradient, where the coordinate axes represent the physical position and temperature value of the battery pack, respectively, to obtain a single cell temperature distribution diagram.

5. The method for modeling a battery pack thermal model according to claim 4, characterized in that: The step S2 of identifying the monomer thermal resistance flow path of the monomer temperature distribution diagram includes: The monomer temperature distribution map is divided into regions according to the temperature range, and the temperature range of each region is set to 5°C; In each temperature gradient region, the temperature difference between adjacent single cells is measured, and the ratio of the temperature difference to the distance between adjacent single cells is calculated to obtain temperature-distance difference ratio data; If the temperature-distance difference ratio data is greater than 0.3°C / cm, it is preliminarily determined that the single cell corresponding to the temperature-distance difference ratio data is the starting point of the thermal resistance flow path; Determine the direction of the thermal resistance flow path based on the starting point of the thermal resistance flow path; if the single cells are connected in parallel, the direction of the thermal resistance flow path is perpendicular to the current flow direction; if the single cells are connected in series, the direction of the thermal resistance flow path is along the current flow direction; The intensity of the thermal resistance flow path is determined by comparing the temperature difference between the temperature gradient regions. The greater the temperature difference between the temperature gradient regions, the higher the intensity of the thermal resistance flow path. The direction and intensity of the thermal resistance flow path are marked on the monomer temperature distribution diagram with red lines, and the marked thermal resistance flow path is superimposed on the monomer temperature distribution diagram to form the monomer thermal resistance flow path.

6. The method for modeling a battery pack thermal model according to claim 1, characterized in that: The step S2 of constructing the initial thermal model of the battery pack based on the cell topology and the cell thermal resistance flow path includes: Convert the cell topology and the cell thermal resistance flow path into a battery cell file, and import the battery cell file into Solidworks software; Set the single cell as a thermal network node according to the single cell topology, determine the arrangement, connection structure and battery layout of the single cell, and mark the position and size of each single cell; The thermal resistance flow path is set as the connecting edge between the thermal network nodes, and the thermal resistance parameters between the nodes are set; Connect the thermal resistance flow paths of adjacent single cells; if they are series cells, the current directions are connected sequentially; if they are parallel cells, the current directions are connected perpendicular to the parallel currents; The Solidworks simulation function is started to build an initial thermal model of the battery pack.

7. The method for modeling a battery pack thermal model according to claim 1, characterized in that: Inputting the battery cell operating parameters into the initial thermal model of the battery pack and evaluating the thermal energy state within the pack in step S3 includes: Inputting the battery cell operating parameters into the initial thermal model of the battery pack; Set the initial conditions of the battery cell temperature, and set the initial temperature to 25°C and the coolant temperature to 20°C; Set the battery cell operation mode to intermittent charge and discharge, and set the charge and discharge current to 1A and the charge and discharge voltage to 5V; Continuously monitor the temperature values ​​of the middle battery and the batteries on both sides of the group, and calculate the temperature difference between the temperature values ​​of the middle battery and the batteries on both sides of the group to obtain the temperature aggregation data within the group; Mark the temperature aggregation space of the temperature aggregation data within the group, and divide the temperature aggregation space into temperature aggregation points; The thermal energy parameters around the temperature gathering point are monitored incrementally with a circle of 0.1 cm radius to obtain the thermal energy diffusion data within the group; The thermal energy diffusion data within the group is subjected to diffusion gradient identification, and the thermal energy state of the diffusion gradient is evaluated to obtain the thermal energy state data of the battery group.

8. The method for modeling a battery pack thermal model according to claim 1, characterized in that: The step S3 of identifying the thermal imbalance area of ​​the battery pack thermal energy status data includes: Calculate the average temperature of the single cells in the battery pack according to the thermal energy status data of the battery pack; The difference between the temperature of each single battery and the average temperature is counted. When the difference exceeds 2°C, the battery is marked as a temperature abnormal point. If there are more than three temperature anomaly points in an area, and the temperature anomaly points are connected to each other, the area is determined to be a potential thermal imbalance area; Conduct voltage and current detection on cells in potential thermal imbalance areas, and set the voltage threshold to ±10% of the rated voltage of the cell, and the current threshold to ±20% of the rated current; When the voltage or current of a single cell exceeds the corresponding threshold, it is recorded as an abnormal state; if a single cell has abnormal temperature, abnormal voltage and abnormal current at the same time, it is determined that the battery cell has thermal runaway, and the potential thermal imbalance area where the battery cell is located is determined as the thermal imbalance area and recorded as thermal imbalance area data.

9. The method for modeling a battery pack thermal model according to claim 1, characterized in that: Step S4 includes the following steps: Step S41: dividing the thermal imbalance area data into a high-risk area, a medium-risk area and a normal area to determine the thermal imbalance division area; Step S42: color-marking the initial thermal model of the battery pack according to the thermal imbalance division area, wherein red indicates a high-risk area, yellow indicates a medium-risk area, and green indicates a normal area; determining the thermally unbalanced battery cell according to the model color marking information; Step S43: increasing the cooling wind speed of the area of ​​the thermally unbalanced battery cell and reducing the number of charge and discharge times to obtain optimized parameters of the thermally unbalanced battery; Step S44: transmitting the thermally unbalanced battery optimization parameters back to the initial thermal model of the battery pack to obtain the thermal model of the battery pack.

10. A modeling system for a battery pack thermal model, characterized in that: A method for modeling a battery pack thermal model according to claim 1, wherein the modeling system of the battery pack thermal model comprises: The cell electrical temperature parameter acquisition module is used to determine the battery cell position inside the battery pack; identify the cell topology structure of the battery cell position, and collect the cell electrical temperature parameters of the battery cell position; The module for constructing the initial thermal model of the battery pack is used to measure the difference in the electrical temperature gradient of the electrical temperature parameters of the cells and generate the data of the electrical temperature difference of the cells; to detect the distribution of the temperature field of the cells on the topological structure of the cells using the electrical temperature difference data of the cells and draw the temperature distribution diagram of the cells; to identify the thermal resistance flow path of the cells in the temperature distribution diagram of the cells; and to construct the initial thermal model of the battery pack based on the topological structure of the cells and the thermal resistance flow path of the cells; The thermal state region detection module is used to input the battery cell operating parameters into the initial thermal model of the battery pack, and to evaluate the thermal energy state within the pack to obtain the thermal energy state data of the battery pack; to identify the thermal imbalance region of the thermal energy state data of the battery pack to generate the thermal imbalance region data; The thermal imbalance identification and optimization module is used to mark the thermally unbalanced battery cells in the initial thermal model of the battery pack according to the thermal imbalance area data, and to perform regional heat dissipation optimization on the thermally unbalanced battery cells to obtain the thermal model of the battery pack.

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