A method and apparatus for detecting temperature of a battery pack

Abstract

The application discloses a battery pack temperature detection method and device. According to the heat generation of the battery pack, the initial temperature at the current moment and the boundary condition of the module in the charging and discharging process of the battery cell, a three-dimensional transient heat conduction equation capable of reflecting the temperature change of the battery cell with time and the temperature distribution in the three-dimensional coordinate direction is constructed, and the model and the boundary condition of the battery cell are simplified to accelerate the temperature solution. The equation is solved to obtain the solution temperature of the battery cell at the current moment. The temperature is taken as the initial temperature to detect the battery cell temperature at the next moment. The application only relies on a small amount of NTC and ambient temperature point real-time data, and can realize real-time prediction of the global temperature of all battery cells in the battery pack, reduces the number of sensors arranged for monitoring the battery cell temperature, reduces the cost of the battery pack and simplifies the operation.

Description

Technical Field

[0001] This application relates to the field of battery temperature detection technology, and in particular to a method and apparatus for detecting the temperature of a battery pack. Background Technology

[0002] With the development of electric vehicles, battery safety has become a major concern. Prolonged operation of batteries outside their optimal operating temperature range will lead to a decline in performance, including reduced efficiency, cycle life, and usable capacity. In severe cases, it can even cause thermal runaway, resulting in safety incidents. Therefore, temperature monitoring of battery packs is crucial.

[0003] In existing technologies, thermistors (NTCs) are typically placed at predetermined locations within the battery pack for real-time temperature monitoring. Alternatively, commercial software is used to calculate the cell temperature field based on the acquired boundary conditions to obtain the global temperature field of the cell. The former method has the drawback of not being able to obtain the global temperature field distribution of the cell, and therefore cannot monitor the temperature at locations where NTCs are not placed. The latter method suffers from the drawback of the cumbersome and time-consuming calculation steps of commercial software, making real-time calculations difficult under real-time boundary conditions. Therefore, a faster method for obtaining the temperature field distribution is needed for efficient detection of the battery pack temperature. Summary of the Invention

[0004] To address the aforementioned issues, this application provides a method and apparatus for detecting battery pack temperature, which can easily and quickly acquire the distribution of the global temperature field of the battery cell, thereby enabling comprehensive and efficient detection of the battery pack temperature.

[0005] This application discloses a method for detecting the temperature of a battery pack, the method comprising:

[0006] Based on the heat generated during the charging and discharging process of the battery cells in the battery pack, the initial temperature of the battery cells at the current moment, and the boundary conditions of the module, a three-dimensional transient heat conduction equation is constructed.

[0007] Solve the three-dimensional transient thermal conduction equation to obtain the solution temperature of the battery cell at the current moment;

[0008] The solution temperature at the current moment is taken as the initial temperature at the current moment, and the next moment is taken as the current moment. The process is then repeated to complete the step of constructing the three-dimensional transient heat conduction equation.

[0009] Optionally, before constructing the three-dimensional transient heat conduction equation, the method further includes:

[0010] Based on the principle of linear interpolation, the thermistor NTC measurement value is assigned to the entire battery cell, and the obtained temperature of the entire battery cell is used as the initial temperature at the current moment.

[0011] Define the boundary conditions for each surface of the module; each surface of the module includes a bottom surface in contact with the cold plate, a top surface parallel to the bottom surface, and a side surface perpendicular to the bottom surface and the top surface; the third type of boundary condition of the top surface is related to the corrected temperature of the ambient temperature measuring point.

[0012] Optionally, the construction of the three-dimensional transient heat conduction equation includes:

[0013] Based on the preset temperature correction at the ambient temperature measuring point, the third type of boundary condition of the top surface is obtained, and combined with the heat generation and the initial temperature at the current moment, the original three-dimensional transient heat conduction equation is constructed.

[0014] The original three-dimensional transient heat conduction equation is calculated iteratively until the convergence condition is met, thus obtaining the three-dimensional transient heat conduction equation.

[0015] Optionally, the iterative calculation of the original three-dimensional transient heat conduction equation until the convergence condition is met includes:

[0016] Calculate the original three-dimensional transient heat conduction equation for the first iteration step to obtain the first output value;

[0017] The original three-dimensional transient heat conduction equation for the second iteration step is obtained based on the first output value;

[0018] Calculate the original three-dimensional transient heat conduction equation for the second iteration step to obtain the second output value;

[0019] The difference between the second output value and the first output value is taken as the temperature residual.

[0020] When the temperature residual satisfies the preset condition, it is determined that the original three-dimensional transient heat conduction equation satisfies the convergence condition;

[0021] When the temperature residual does not meet the preset condition, the iterative calculation of the temperature residual is repeated until the temperature residual meets the preset condition; the preset condition is that the temperature residual is less than a threshold.

[0022] Optionally, solving the three-dimensional transient heat conduction equation includes:

[0023] Solve the three-dimensional transient heat conduction equation to obtain the solution temperature of the top surface;

[0024] When the comparison result between the solved temperature and the NTC measurement value of the top surface meets the preset requirements, the corrected temperature of the ambient temperature measuring point is determined.

[0025] When the comparison result does not meet the preset requirements, the correction temperature of the ambient temperature measuring point is modified, the original three-dimensional transient heat conduction equation is reconstructed and iterative calculation is performed until the comparison result meets the preset requirements.

[0026] Optionally, modifying the correction temperature of the ambient temperature measuring point includes:

[0027] The temperature is adjusted ± the compensation temperature based on the corrected temperature at the ambient temperature measuring point.

[0028] Optionally, the preset correction temperature for the ambient temperature measuring point is the ambient temperature measuring point temperature.

[0029] Optionally, the construction of the three-dimensional transient heat conduction equation includes:

[0030] Ignoring the thermally conductive adhesive, cold plate structure, and electrode structure in the battery pack, the battery pack is divided into multiple grids according to the modules;

[0031] The three-dimensional transient heat conduction equation is constructed based on the mesh.

[0032] Based on the above-mentioned method for detecting battery pack temperature, this application also discloses a device for detecting battery pack temperature, including: a construction unit and a solution unit;

[0033] The construction unit is used to construct a three-dimensional transient thermal conductivity equation based on the heat generated during the charging and discharging process of the battery cell in the battery pack, the initial temperature of the battery cell at the current moment, and the boundary conditions of the module.

[0034] The solving unit is used to solve the three-dimensional transient thermal conduction equation and obtain the solution temperature of the battery cell at the current moment;

[0035] It is also used to take the solution temperature at the current moment as the initial temperature at the current moment, and take the next moment as the current moment, and return to execute the step of constructing the three-dimensional transient heat conduction equation.

[0036] Optionally, the device further includes:

[0037] The acquisition unit is used to assign the NTC measurement value of the thermistor to the entire battery cell based on the principle of linear interpolation, and use the obtained temperature of the entire battery cell as the initial temperature at the current moment.

[0038] A definition unit is used to define the boundary conditions of each surface of the module; each surface of the module includes a bottom surface in contact with the cold plate, a top surface parallel to the bottom surface, and a side surface perpendicular to the bottom surface and the top surface; the third type of boundary condition of the top surface is related to the corrected temperature of the ambient temperature measuring point.

[0039] Optionally, the building unit includes:

[0040] A sub-unit is constructed to obtain the third type of boundary conditions of the top surface based on the preset ambient temperature measurement point correction temperature, and to construct the original three-dimensional transient heat conduction equation by combining the heat generation and the initial temperature at the current moment.

[0041] An iterative sub-unit is used to iteratively calculate the original three-dimensional transient heat conduction equation until the convergence condition is met, thereby obtaining the three-dimensional transient heat conduction equation.

[0042] Optionally, the iterative subunit includes:

[0043] The first computational subunit is used to calculate the original three-dimensional transient heat conduction equation for the first iteration step and obtain the first output value;

[0044] Obtain a sub-unit, used to obtain the original three-dimensional transient heat conduction equation for the second iteration step based on the first output value;

[0045] The second computational subunit is used to calculate the original three-dimensional transient heat conduction equation for the second iteration step and obtain the second output value;

[0046] The residual subunit is used to treat the difference between the second output value and the first output value as the temperature residual.

[0047] A sub-unit is defined to determine that the original three-dimensional transient heat conduction equation satisfies the convergence condition when the temperature residual satisfies the preset condition.

[0048] The repeating subunit is used to repeat the iterative calculation of the temperature residual when the temperature residual does not meet the preset condition, until the temperature residual meets the preset condition; the preset condition is that the temperature residual is less than a threshold.

[0049] Optionally, the solution unit includes:

[0050] The top surface solver sub-element is used to solve the three-dimensional transient heat conduction equation and obtain the solution temperature of the top surface;

[0051] The correction determination subunit is used to determine the correction temperature of the ambient temperature measuring point when the comparison result between the solved temperature and the NTC measurement value of the top surface meets the preset requirements.

[0052] The sub-unit is reconstructed to modify the ambient temperature measurement point correction temperature when the comparison result does not meet the preset requirements, reconstruct the original three-dimensional transient heat conduction equation and perform iterative calculations until the comparison result meets the preset requirements.

[0053] Optionally, the reconstructed subunit is used for:

[0054] The temperature is adjusted ± the compensation temperature based on the corrected temperature at the ambient temperature measuring point.

[0055] Optionally, the preset correction temperature for the ambient temperature measuring point is the ambient temperature measuring point temperature.

[0056] Optionally, the building unit is used for:

[0057] Sub-units are used to ignore the thermally conductive adhesive, cold plate structure and electrode structure in the battery pack, and to divide the battery pack into multiple grids according to the modules;

[0058] Mesh sub-units are used to construct the three-dimensional transient heat conduction equation based on the mesh.

[0059] Based on the above-described method for detecting battery pack temperature, this application also discloses a computer program product, including a computer program that, when executed by a processor, implements the steps of the above-described method.

[0060] This application discloses a method and apparatus for detecting battery pack temperature. Based on the heat generated during the charging and discharging process of the battery cells, the initial temperature at the current moment, and the boundary conditions of the module, a three-dimensional transient heat conduction equation is constructed that reflects the temperature change of the cells over time and the temperature distribution along the three-dimensional coordinate direction. The cell model and boundary conditions are simplified to accelerate temperature calculation. Solving this equation yields the cell temperature at the current moment. This temperature is then used as the initial temperature for detecting the cell temperature at the next moment. This application relies only on a small number of thermistors (NTCs) and real-time ambient temperature data to achieve real-time prediction of the global temperature of all cells within the battery pack, reducing the number of sensors required for monitoring cell temperature, lowering battery pack costs, and simplifying operation. Attached Figure Description

[0061] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0062] Figure 1a This is a schematic flowchart of a battery pack temperature detection method disclosed in an embodiment of this application;

[0063] Figure 1b This is a schematic diagram of the battery pack structure disclosed in the embodiments of this application;

[0064] Figure 1c This is a schematic diagram of the bottom boundary conditions disclosed in the embodiments of this application;

[0065] Figure 2 This is a flowchart illustrating another method for detecting battery pack temperature disclosed in an embodiment of this application;

[0066] Figure 3This is a schematic diagram of the structure of a battery pack temperature detection device disclosed in an embodiment of this application. Detailed Implementation

[0067] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0068] Example 1: This application discloses a method for detecting the temperature of a battery pack.

[0069] For details, please refer to Figure 1a The battery pack temperature detection method disclosed in this embodiment includes the following steps:

[0070] Step 101: Based on the heat generated during the charging and discharging process of the battery cells in the battery pack, the initial temperature of the battery cells at the current moment, and the boundary conditions of the module, construct a three-dimensional transient heat conduction equation.

[0071] In the method described in this embodiment, it is necessary to obtain the number of battery cells in the battery pack, the cell dimensions (length, height, and thickness), and physical property parameters (thermal conductivity of the cell in the three directions of length X, height Y, and thickness Z, cell density, and specific heat capacity at constant pressure). Figure 1b Taking the battery pack shown as an example, the main structure of this battery pack consists of 64 battery cells, 16 welded thermistors (NTCs), a cold plate for thermal management, and thermally conductive adhesive between the battery cells and the cold plate. Figure 1c As shown, the battery pack consists of multiple modules along... Figure 1c The modules are arranged horizontally side by side, with each module consisting of multiple cells arranged along the same horizontal axis. Figure 1c It consists of vertically arranged components.

[0072] In the method described in this embodiment, the internal structure of the battery pack needs to be appropriately simplified to shorten the calculation time. Specifically, the thermally conductive adhesive, cold plate structure, and electrode tab structure in the battery pack (which account for a small proportion and have a small temperature difference with the top surface of the cells under low-rate (e.g., less than 1C) charge-discharge conditions) can be ignored, and the battery pack can be divided into multiple grids according to modules. That is, each grid can be composed of a module, thermally conductive adhesive, and cold plate.

[0073] In the method described in this embodiment, before constructing the three-dimensional transient heat conduction equation, it is necessary to preset the heat generation during the charging and discharging process of the battery cell, obtain the initial temperature, and define the boundary conditions. The heat generation is a preset value, which can be a preset variable. To make the temperature output by the equation more accurate, the battery cell can be allowed to stand for a certain period of time. When the battery cell temperature stabilizes, the NTC measurement value is assigned to the entire battery cell based on the principle of linear interpolation, and the obtained overall (global) temperature of the battery cell is used as the initial temperature. Whether the battery cell temperature is stable can be determined based on the standing time; for example, when the standing time reaches a preset value, the battery cell temperature is considered stable at the current moment.

[0074] Linear interpolation is a method for estimating or predicting the value of unknown data points based on the linear relationship between two known points on a model of the entire battery cell. Specifically, given the known NTC measurements at two points, a linear interpolation formula can be used to assume a linear change in the NTC values ​​between the two points. Therefore, the NTC value at any location between the two points can be predicted based on these two values. After linear interpolation, a global temperature distribution map of the battery cell or a single temperature value at each location can be obtained, reflecting the temperature status of the battery cell in its current state.

[0075] As an optional approach, all six faces of the module are defined using third-type boundary conditions, and the four sides of the module are defined using third-type boundary conditions h. 自然对流 and T 环温测点温度 The top surface of the module uses the third type of boundary condition h. 自然对流 and T 环温测点修正温度 The four sides can directly use the ambient temperature measurement points, while the top surface requires correction. This is because, for a bottom-cooled cell structure, heat transfer within the cell primarily occurs on the cross-section perpendicular to the cold plate. Accurate boundary conditions in this direction are crucial for cell temperature prediction. Therefore, the reference temperature used for heat transfer calculations on the top surface needs correction. After pre-setting the correction value for the ambient temperature measurement points on the top surface, and obtaining the corrected ambient temperature (the initial corrected ambient temperature can be the ambient temperature measurement point temperature), the third type of boundary conditions for the top surface can be obtained based on the preset corrected ambient temperature measurement point temperature.

[0076] It should be noted that in this embodiment, the bottom surface is the surface in contact with the cold plate, the top surface is the surface parallel to the bottom surface, and the side surface is the surface perpendicular to the bottom and top surfaces.

[0077] In the method described in this embodiment, the third type of boundary condition used on the bottom surface of the module is h. 冷却液 The thermally conductive adhesive and cold plate structure on the bottom surface are omitted, and are approximated by third-type boundary conditions (convective heat transfer coefficient and reference temperature). Figure 1cThis is a schematic diagram of the bottom boundary conditions disclosed in the embodiments of this application, as shown below. Figure 1c As shown on the left, the coolant on the bottom surface of module 1-4 flows along the coolant flow direction within the cold plate. For example... Figure 1c As shown on the right, h 冷却液 The relation is: h 1-冷却液 =f1(y1),h 2-冷却液 =f2(y2),h 3-冷却液 =f3(L-y3), h 4-冷却液 = f4(L-y4). Here, since the flow rate of the coolant at the inlet of the liquid-cooled battery pack remains essentially constant, and the fluid convective heat transfer coefficient is mainly determined by the Reynolds number, i.e., the Reynolds number is constant when the flow rate is constant. Therefore, h 冷却液 A relationship obtained through experiments or high-precision simulation under a specific operating condition can also be applied to other operating conditions. For example... Figure 1c As shown on the right, the reference temperature T f1-冷却液 T f2-冷却液 T f3-冷却液 and T f4-冷却液 Select T 冷却液进口温度 and T 冷却液出口温度 Linear interpolation or other values ​​determined based on the structure of the cold plate.

[0078] In the method described in this embodiment, the coolant and coolant temperature are different for different cold plates. The bottom boundary of other types of battery packs can be simplified to (T) f1-冷却液 h 1-冷却液 ),(T f2-冷却液 h 2-冷却液 ),……(T fn-冷却液 h n-冷却液 ), where n is the number of modules.

[0079] In the method described in this embodiment, a three-dimensional transient heat conduction equation is constructed based on a mesh to reflect the temperature change of the battery cell over time and the temperature distribution along the three-dimensional coordinates of the battery cell. The three-dimensional transient heat conduction equation can be solved under given boundary conditions. The equation is as follows:

[0080]

[0081] In the formula, ρ is density and c is specific heat capacity. The symbol is a partial differential, T is the initial temperature, t is time, S is the heat generated, x, y, z are the coordinates in three directions, and λ is the thermal conductivity, which is different in the three directions.

[0082] In the method described in this embodiment, parallel programs can be written using languages ​​such as C, C++, Python, or Fortran. The number of CPU cores is selected according to the number of modules in the specific battery pack for parallel computing.

[0083] Step 102: Solve the three-dimensional transient thermal conductivity equation to obtain the solution temperature of the battery cell at the current moment.

[0084] In the method described in this embodiment, a first output value is obtained by calculating the three-dimensional transient heat conduction equation of the first iteration step. Based on the first output value, the three-dimensional transient heat conduction equation of the second iteration step is obtained, and a second output value is calculated. Finally, the difference between the second output value and the first output value is taken as the temperature residual. The temperature residual can also be in the form of the quotient of the second output value and the first output value, and the specific form of the temperature residual is not limited here.

[0085] When the temperature residual satisfies the convergence condition, the three-dimensional transient heat conduction equation is confirmed to have convergence, and this equation can be used to output the temperature. Conversely, when the temperature residual does not satisfy the convergence condition, it indicates that the three-dimensional transient heat conduction equation does not meet the convergence condition. The iterative calculation of the temperature residual is then repeated until the temperature residual satisfies the convergence condition. The convergence condition can be that the temperature residual is less than a threshold (e.g., 0.0001), and its specific type and value can be set according to actual needs, without limitation here.

[0086] In the method described in this embodiment, after the three-dimensional transient heat conduction equation converges, the correction value of the ambient temperature measurement point on the top surface of the battery cell, which was preset in step 101, needs to be verified. If the verification fails, iterative iteration can be performed within a certain range above and below the correction value of the ambient temperature measurement point on the top surface of the battery cell (which can be set according to actual needs, for example, ±5℃).

[0087] Specifically, the iterative process involves solving the converged three-dimensional transient heat conduction equation to obtain the output temperature of the top surface of the battery cell. When the comparison between the output temperature and the NTC measurement value of the top surface of the battery cell meets preset requirements, a correction value for the ambient temperature measurement point on the top surface of the battery cell is determined. Meeting the preset requirements can be either a difference less than a threshold or a quotient within a preset range. The specific type of comparison result or the specific content of the preset requirements are not limited here; the goal is simply to determine the correction value for the ambient temperature measurement point on the top surface of the battery cell.

[0088] Furthermore, as an example, considering that the NTC measurement values ​​at both ends of the module deviate significantly from the temperature values ​​at the top of the cell, the average of the two NTC measurement values ​​in the middle of the module can be used as the NTC measurement value. In practice, it is not limited to selecting only the two middle NTC measurement values; any NTC measurement value that deviates from the two ends of the module can be used for verification. And it is not limited to using only the average value.

[0089] Accordingly, if the comparison result does not meet the preset requirements, the temperature correction value of the ambient temperature measuring point is modified, and the calculation is re-iterated until the comparison result meets the preset requirements. The method for modifying the ambient temperature measuring point temperature correction value can be to ± the compensation temperature (which can be set according to actual needs, for example, 2℃) based on the ambient temperature measuring point temperature correction value.

[0090] Step 103: Take the solution temperature at the current moment as the initial temperature at the current moment, and take the next moment as the current moment, and return to execute the step of constructing the three-dimensional transient heat conduction equation.

[0091] The temperature of the battery cell at the current moment is used as the initial temperature in the three-dimensional transient heat conduction equation for the next moment.

[0092] In the method described in this embodiment, data such as the coolant temperature at the inlet and outlet of the cold plate, the ambient temperature measuring point temperature, and the NTC measurement value can be acquired in real time in devices such as the battery control system, local control, and battery management system in the energy storage product.

[0093] The method described in this embodiment simplifies the computational model of the battery pack by dividing it into multiple meshes based on the modules and simplifying the boundary conditions on the bottom surface of the modules, thereby shortening the time required to solve the temperature field. Simultaneously, it uses real-time NTC measurements from the battery pack for calibration, improving the accuracy of the transient temperature field prediction for the cells. The method described in this embodiment relies on only a small number of NTC measurements and real-time ambient temperature data to predict the global temperature of all cells within the battery pack in real time, eliminating the need for numerous temperature monitoring sensors, making it easier to implement and reducing detection costs.

[0094] Example 2: This application discloses another method for detecting battery pack temperature. Please refer to [link / reference]. Figure 2 This embodiment describes the entire process of temperature detection.

[0095] Step 201: Input the number of battery cells, cell size, and physical properties of the battery pack.

[0096] Step 202: Preset the heat generated during the charging and discharging process of the battery cell and obtain the initial temperature.

[0097] Step 203: Set boundary conditions for the sides and bottom of the module.

[0098] Step 204: Set the correction value of the ambient temperature measurement point on the top surface of the module to obtain the boundary conditions of the top surface of the module.

[0099] Step 205: Construct and obtain the output values ​​of the three-dimensional transient heat conduction equation.

[0100] Step 206: Determine whether the temperature residual between the output value and the output value of the previous iteration satisfies the convergence condition. If yes, proceed to step 207. If yes, repeat step 206 iteratively.

[0101] Step 207: Obtain the output temperature of the top surface of the battery cell.

[0102] Step 208: Determine whether the comparison result between the output temperature and the NTC measurement value on the top surface of the battery cell meets the preset requirements. If yes, proceed to step 209. If yes, proceed to step 210.

[0103] Step 209: Obtain the current global cell temperature output by the three-dimensional transient heat conduction equation, and use this temperature as the initial temperature for the next moment. Return to step 204.

[0104] Step 210: Modify the temperature correction value of the ambient temperature measuring point in the boundary conditions of the top surface of the module to obtain the boundary conditions of the top surface of the module. Repeat step 205.

[0105] Based on the battery pack temperature detection method disclosed in the above embodiments, this embodiment correspondingly discloses a battery pack temperature detection device. Please refer to... Figure 3 The device for detecting battery pack temperature includes: a construction unit 301 and a solution unit 302;

[0106] The construction unit 301 is used to construct a three-dimensional transient thermal conductivity equation based on the heat generated during the charging and discharging process of the battery cell in the battery pack, the initial temperature of the battery cell at the current moment, and the boundary conditions of the module.

[0107] The solving unit 302 is used to solve the three-dimensional transient thermal conduction equation and obtain the solution temperature of the battery cell at the current moment.

[0108] It is also used to take the solution temperature at the current moment as the initial temperature at the current moment, and take the next moment as the current moment, and return to execute the step of constructing the three-dimensional transient heat conduction equation.

[0109] Optionally, the device further includes:

[0110] The acquisition unit is used to assign the NTC measurement value of the thermistor to the entire battery cell based on the principle of linear interpolation, and use the obtained temperature of the entire battery cell as the initial temperature at the current moment.

[0111] A definition unit is used to define the boundary conditions of each surface of the module; each surface of the module includes a bottom surface in contact with the cold plate, a top surface parallel to the bottom surface, and a side surface perpendicular to the bottom surface and the top surface; the third type of boundary condition of the top surface is related to the corrected temperature of the ambient temperature measuring point.

[0112] Optionally, the building unit 301 includes:

[0113] A sub-unit is constructed to obtain the third type of boundary conditions of the top surface based on the preset ambient temperature measurement point correction temperature, and to construct the original three-dimensional transient heat conduction equation by combining the heat generation and the initial temperature at the current moment.

[0114] An iterative sub-unit is used to iteratively calculate the original three-dimensional transient heat conduction equation until the convergence condition is met, thereby obtaining the three-dimensional transient heat conduction equation.

[0115] Optionally, the iterative subunit includes:

[0116] The first computational subunit is used to calculate the original three-dimensional transient heat conduction equation for the first iteration step and obtain the first output value;

[0117] Obtain a sub-unit, used to obtain the original three-dimensional transient heat conduction equation for the second iteration step based on the first output value;

[0118] The second computational subunit is used to calculate the original three-dimensional transient heat conduction equation for the second iteration step and obtain the second output value;

[0119] The residual subunit is used to treat the difference between the second output value and the first output value as the temperature residual.

[0120] A sub-unit is defined to determine that the original three-dimensional transient heat conduction equation satisfies the convergence condition when the temperature residual satisfies the preset condition.

[0121] The repeating subunit is used to repeat the iterative calculation of the temperature residual when the temperature residual does not meet the preset condition, until the temperature residual meets the preset condition; the preset condition is that the temperature residual is less than a threshold.

[0122] Optionally, the solving unit 302 includes:

[0123] The top surface solver sub-element is used to solve the three-dimensional transient heat conduction equation and obtain the solution temperature of the top surface;

[0124] The correction determination subunit is used to determine the correction temperature of the ambient temperature measuring point when the comparison result between the solved temperature and the NTC measurement value of the top surface meets the preset requirements.

[0125] The sub-unit is reconstructed to modify the ambient temperature measurement point correction temperature when the comparison result does not meet the preset requirements, reconstruct the original three-dimensional transient heat conduction equation and perform iterative calculations until the comparison result meets the preset requirements.

[0126] Optionally, the reconstructed subunit is used for:

[0127] The temperature is adjusted ± the compensation temperature based on the corrected temperature at the ambient temperature measuring point.

[0128] Optionally, the preset correction temperature for the ambient temperature measuring point is the ambient temperature measuring point temperature.

[0129] Optionally, the building unit 301 is used for:

[0130] Sub-units are used to ignore the thermally conductive adhesive, cold plate structure and electrode structure in the battery pack, and to divide the battery pack into multiple grids according to the modules;

[0131] Mesh sub-units are used to construct the three-dimensional transient heat conduction equation based on the mesh.

[0132] Based on the above-described method for detecting battery pack temperature, this application also discloses a computer program product, including a computer program that, when executed by a processor, implements the steps of the above-described method.

[0133] The embodiments in this specification are described in a progressive manner. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant details can be found in the method section.

[0134] It should also be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0135] The steps of the methods or algorithms described in conjunction with the embodiments disclosed herein can be implemented directly by hardware, a software module executed by a processor, or a combination of both. The software module can be located in random access memory (RAM), main memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, removable disk, CD-ROM, or any other form of storage medium known in the art.

[0136] The features described in the embodiments of this specification can be substituted for or combined with each other, so that those skilled in the art can implement or use this application.

[0137] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily 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 this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for detecting the temperature of a battery pack, characterized in that, include: Based on the heat generated during the charging and discharging process of the battery cells in the battery pack, the initial temperature of the battery cells at the current moment, and the boundary conditions of the module, a three-dimensional transient heat conduction equation is constructed. Solve the three-dimensional transient thermal conduction equation to obtain the solution temperature of the battery cell at the current moment; The solution temperature at the current moment is taken as the initial temperature at the current moment, and the next moment is taken as the current moment. The process is then repeated to complete the step of constructing the three-dimensional transient heat conduction equation.

2. The method according to claim 1, characterized in that, Before constructing the three-dimensional transient heat conduction equation, the method further includes: Based on the principle of linear interpolation, the thermistor NTC measurement value is assigned to the entire battery cell, and the obtained temperature of the entire battery cell is used as the initial temperature at the current moment. Define the boundary conditions for each surface of the module; each surface of the module includes a bottom surface in contact with the cold plate, a top surface parallel to the bottom surface, and a side surface perpendicular to the bottom surface and the top surface; the third type of boundary condition of the top surface is related to the corrected temperature of the ambient temperature measuring point.

3. The method according to claim 2, characterized in that, The construction of the three-dimensional transient heat conduction equation includes: Based on the preset temperature correction at the ambient temperature measuring point, the third type of boundary condition of the top surface is obtained, and combined with the heat generation and the initial temperature at the current moment, the original three-dimensional transient heat conduction equation is constructed. The original three-dimensional transient heat conduction equation is calculated iteratively until the convergence condition is met, thus obtaining the three-dimensional transient heat conduction equation.

4. The method according to claim 3, characterized in that, The iterative calculation of the original three-dimensional transient heat conduction equation until the convergence condition is met includes: Calculate the original three-dimensional transient heat conduction equation for the first iteration step to obtain the first output value; The original three-dimensional transient heat conduction equation for the second iteration step is obtained based on the first output value; Calculate the original three-dimensional transient heat conduction equation for the second iteration step to obtain the second output value; The difference between the second output value and the first output value is taken as the temperature residual. When the temperature residual satisfies the preset condition, it is determined that the original three-dimensional transient heat conduction equation satisfies the convergence condition; When the temperature residual does not meet the preset condition, the iterative calculation of the temperature residual is repeated until the temperature residual meets the preset condition; the preset condition is that the temperature residual is less than a threshold.

5. The method according to claim 4, characterized in that, Solving the three-dimensional transient heat conduction equation includes: Solve the three-dimensional transient heat conduction equation to obtain the solution temperature of the top surface; When the comparison result between the solved temperature and the NTC measurement value of the top surface meets the preset requirements, the corrected temperature of the ambient temperature measuring point is determined. When the comparison result does not meet the preset requirements, the correction temperature of the ambient temperature measuring point is modified, the original three-dimensional transient heat conduction equation is reconstructed and iterative calculation is performed until the comparison result meets the preset requirements.

6. The method according to claim 5, characterized in that, The modification of the ambient temperature measuring point correction temperature includes: The temperature is adjusted ± the compensation temperature based on the corrected temperature at the ambient temperature measuring point.

7. The method according to claim 3, characterized in that, The preset correction temperature for the ambient temperature measuring point is the ambient temperature measuring point temperature.

8. The method according to any one of claims 1-7, characterized in that, The construction of the three-dimensional transient heat conduction equation includes: Ignoring the thermally conductive adhesive, cold plate structure, and electrode structure in the battery pack, the battery pack is divided into multiple grids according to the modules; The three-dimensional transient heat conduction equation is constructed based on the mesh.

9. A device for detecting the temperature of a battery pack, characterized in that, include: Constructing elements and solving elements; The construction unit is used to construct a three-dimensional transient thermal conductivity equation based on the heat generated during the charging and discharging process of the battery cell in the battery pack, the initial temperature of the battery cell at the current moment, and the boundary conditions of the module. The solving unit is used to solve the three-dimensional transient thermal conduction equation and obtain the solution temperature of the battery cell at the current moment; It is also used to take the solution temperature at the current moment as the initial temperature at the current moment, and take the next moment as the current moment, and return to execute the step of constructing the three-dimensional transient heat conduction equation.

10. A computer program product, comprising a computer program, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1-8.

Images