System and method for measuring thermal runaway eruption kinetic parameters of lithium battery

Abstract

The invention relates to the technical field of lithium battery eruption parameter measurement, in particular to a lithium battery thermal runaway eruption kinetic parameter measurement system and method, and the method specifically comprises the steps: controlling the use state of a high-speed camera array; constructing a dynamic field model and a thermal distribution model under thermal runaway eruption of the lithium battery; calculating a first sampling validity, and adjusting the initial sampling frequency to obtain a first adjustment frequency; calculating a lithium battery injection coefficient, and drawing a change trend curve; evaluating a second sampling validity degree, and dynamically controlling the sampling frequency of the high-speed camera array to obtain a second adjustment frequency; and keeping the second adjustment frequency to measure the out-of-control eruption process of the lithium battery. The problem that in the prior art, due to the fact that the lithium battery thermal runaway eruption speed is high, and the sampling frequency of a camera is difficult to dynamically adjust in real time according to eruption parameters of the lithium battery, collected data in the lithium battery thermal runaway eruption process is not comprehensive is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium battery eruption parameter measurement, in particular to a lithium battery thermal runaway eruption dynamics parameter measurement system and method. Background Art

[0002] As a high-energy-density energy storage device, lithium batteries are widely used in electronic products, electric vehicles, and other high-power demand fields. However, lithium batteries may experience thermal runaway under abnormal conditions, causing the internal temperature of the battery to rise sharply, eventually triggering violent eruptions and explosions. This thermal runaway eruption may not only pose a serious safety threat to equipment and users, but also pose potential risks to the environment and public safety. A notable feature of lithium battery thermal runaway eruptions is the extremely fast ejection speed. During the eruption process, the high-temperature gas and electrolyte inside the battery will be rapidly released to form a high-speed jet stream. The speed of this jet phenomenon usually reaches several meters per second or even higher, making it extremely challenging to accurately measure the eruption process. In the study of thermal runaway eruptions of lithium batteries, accurate measurement of kinetic parameters is crucial. By measuring parameters such as the eruption velocity, jet angle, and distribution of erupted materials, we can gain a deeper understanding of the dynamic characteristics of the thermal runaway process, thereby providing improvement suggestions for battery design and a basis for optimizing the protection system. However, due to the following problems, the actual measurement process faces many difficulties: First, the eruption point of thermal runaway of lithium batteries cannot usually be accurately determined in advance. This uncertainty makes it difficult to set the camera's shooting angle in advance. The randomness of the eruption point may cause the camera to be unable to capture the eruption process at the optimal angle, thereby affecting the accuracy of the measurement results; second, the eruption speed of lithium batteries during thermal runaway is extremely fast, which may exceed The rapid changes in eruption speed exceed the sampling capacity of traditional camera systems. The camera system must have a sufficiently high sampling frequency to capture the rapid changes during the eruption. If the sampling frequency is insufficient, important dynamic features of the eruption process may be missed, resulting in the inflection point data of the eruption trend curve cannot be accurately recorded. If the sampling frequency is too fast, the computer's real-time data processing capacity will increase. Finally, due to the large changes in eruption speed, the statically set sampling frequency may not be able to adapt to the eruption characteristics at different stages. Therefore, the camera's sampling frequency needs to be dynamically adjusted to ensure that the key data of speed changes can be accurately recorded throughout the eruption process.

[0003] Among the existing disclosed invention technologies, Chinese patent publication number CN118376931A discloses a lithium battery thermal runaway simulation test system and test method, wherein the test system includes a battery thermal runaway trigger device, an ejecta post-processing device, an ejecta storage device, an online flammability test device, and a control system connected in sequence; the ejecta collection device in the battery thermal runaway trigger device can comprehensively collect the battery thermal runaway ejecta, and the ejecta post-processing device, the ejecta storage device, and the online flammability test device can collect and ignite the ejecta in real time according to a unit time step online, and can perform real-time and detailed analysis and online flammability testing of the ejecta generated after the battery thermal runaway occurs, providing theoretical and practical guidance for battery thermal runaway prevention and control and prediction of battery ignition behavior after thermal runaway.

[0004] The test system described in the above patent mainly focuses on the collection and processing of eruption materials, and does not involve real-time monitoring of dynamic characteristics during the eruption process, such as eruption speed, eruption angle, etc. The lack of dynamic monitoring of the eruption process will lead to the inability to accurately capture rapid changes and key data during the eruption process, thereby affecting the comprehensive understanding of the dynamic characteristics of thermal runaway. Summary of the Invention

[0005] The technical problem to be solved by the present invention is that, in view of the fast eruption speed of lithium battery thermal runaway, the sampling frequency of the camera is difficult to be dynamically adjusted in real time according to the eruption parameters of the lithium battery, resulting in incomplete data collection during the thermal runaway eruption process of the lithium battery. A system and method for measuring the dynamic parameters of thermal runaway eruption of lithium battery are proposed.

[0006] In order to achieve the above-mentioned object, the technical solution of a method for measuring the dynamic parameters of thermal runaway eruption of a lithium battery of the present invention comprises the following steps:

[0007] S1: Use an infrared camera to monitor the temperature distribution on the surface of the lithium battery in real time, and dynamically control the use status of the high-speed camera array based on the temperature distribution on the surface of the lithium battery;

[0008] S2: Extract the battery status data of the lithium battery under thermal runaway eruption captured by the high-speed camera array, and construct the dynamic field model and thermal distribution model under the thermal runaway eruption of the lithium battery based on the battery status data;

[0009] S3: extracting dynamic characteristic data from the dynamic field model, calculating a first sampling validity based on the dynamic characteristic data, and adjusting an initial sampling frequency of the high-speed camera array based on the first sampling validity to obtain a first adjusted frequency;

[0010] S4: extracting thermodynamic characteristic data from the thermal distribution model, calculating the lithium battery ejection coefficient during the battery thermal runaway eruption process in real time, and drawing a trend curve of the lithium battery ejection coefficient during the lithium battery thermal runaway eruption process versus the eruption time based on the thermodynamic characteristic data;

[0011] S5: Marking data sampling points of the high-speed camera array in the trend curve of the change of the lithium battery ejection coefficient with the ejection time, monitoring the change trend curve in real time, evaluating the second sampling effectiveness of the high-speed camera array, and dynamically controlling the sampling frequency of the high-speed camera array according to the second sampling effectiveness to obtain a second adjustment frequency;

[0012] S6: Maintain the second adjustment frequency to measure the uncontrolled eruption process of the lithium battery.

[0013] Specifically, in S1, the use of an infrared camera to monitor the temperature distribution on the surface of a lithium battery in real time specifically includes: obtaining temperature distribution image data on the surface of the lithium battery, and grayscale processing the temperature distribution image data, presetting the maximum grayscale threshold and the minimum grayscale threshold corresponding to the uncontrolled eruption temperature, screening the pixel points in the temperature distribution image that are within the maximum grayscale threshold and the minimum grayscale threshold, and calibrating the pixel area obtained by screening as the key monitoring area for uncontrolled eruption of lithium batteries.

[0014] Specifically, in S1, dynamically controlling the use status of the high-speed camera array according to the temperature distribution on the surface of the lithium battery specifically includes: extracting the key monitoring area of ​​the uncontrolled eruption of the lithium battery, and controlling the four high-speed cameras through the electric pan-tilt head to keep them in the on state, wherein the first high-speed camera is set to be directly aimed at the front of the lithium battery to capture the main front area of ​​the lithium battery's uncontrolled eruption; the second high-speed camera is set to be on the left side of the lithium battery to capture the main area of ​​the left side of the lithium battery's uncontrolled eruption; the third high-speed camera is set to be on the right side of the lithium battery to capture the main area of ​​the right side of the lithium battery's uncontrolled eruption; and the fourth high-speed camera is set to be directly above the lithium battery to capture the overhead sub-area of ​​the lithium battery's uncontrolled eruption.

[0015] Specifically, the dynamic field model described in S2 includes: real-time eruption velocity data, eruption area length data, eruption angle data and eruption morphology data; the thermal distribution model described in S2 includes: lithium battery surface temperature data, heat flux density data, thermal diffusivity and convective heat transfer coefficient.

[0016] Specifically, in S3, the calculation strategy of the first sampling validity e1 is:

[0017]

[0018] Among them, in the main frontal area of ​​the battery uncontrolled eruption, the length of the eruption area is divided into one meter as a sampling validity unit analysis distance, and a total of X sampling validity unit analysis distances are obtained, where x is the subscript, indicating the xth sampling validity unit analysis distance;

[0019] v x ,v x-1 ,v x+1 The real-time eruption speed of lithium batteries in the x-th, x-1th and x+1th sampling validity units are analyzed respectively;

[0020] The mean of the real-time ejection velocity of the lithium battery in the analysis distance for X sampling validity units.

[0021] Specifically, in S3, the calculation strategy of the first adjustment frequency pl1 is:

[0022] pl1=e1×pl0;

[0023] Where p10 is the initial sampling frequency of the high-speed camera array.

[0024] Specifically, S4 includes the following specific steps:

[0025] S41: extracting thermodynamic characteristic data from the thermal distribution model;

[0026] S42: Real-time calculation of the lithium battery ejection coefficient ps during the battery thermal runaway ejection process. The calculation strategy of the lithium battery ejection coefficient is as follows:

[0027] ps=∫∫∫(ε1×Q1+ε2×Q2)dW;

[0028] Where W is the unit volume of the monitoring enclosed space for thermal runaway eruption of lithium batteries;

[0029] ε1 and ε2 are the combustion heat ratio coefficient and the convection heat ratio coefficient respectively;

[0030] Q1 is the combustion heat released by the thermal runaway eruption of the lithium battery into the monitored enclosed space;

[0031] Q1 = ln[R′(t) + 2.32], where R′(t) is the heat function of the lithium battery thermal runaway eruption;

[0032] Q2 is the heat generated by thermal convection between the air and the lithium battery in the enclosed space during the thermal runaway eruption of the lithium battery; S ldc is the surface area of ​​the lithium battery; Te max ,Te min The maximum and minimum temperatures on the surface of the lithium battery during the thermal runaway eruption of the lithium battery; are the average surface temperature of the lithium battery and the average air temperature in the monitored enclosed space during the thermal runaway eruption of the lithium battery; hc is the convective heat transfer coefficient;

[0033] S43: Draw a trend curve of the lithium battery ejection coefficient during the thermal runaway eruption process of the lithium battery as a function of the eruption time.

[0034] Specifically, S5 includes the following specific steps:

[0035] S51: In the trend curve of the lithium battery ejection coefficient versus ejection time, mark the data sampling points of the high-speed camera array and obtain the data sampling point set {A1, A2...A j ...A J}, where j is a subscript, indicating the jth data sampling point of the high-speed camera array, and J is the total number of data sampling points; A j Indicates the sampling time point corresponding to the j-th data sampling point;

[0036] S52: Monitor the change trend curve in real time and evaluate the second sampling effectiveness e2 of the high-speed camera array. The calculation strategy of the second sampling effectiveness is specifically as follows:

[0037]

[0038] Among them, g′ j ,g′ j-1 ,g′ j+1 Respectively represent the derivative values ​​of the change trend curve at the jth, j-1th and j+1th data sampling points; Indicates the positive midpoint of the change trend curve between the sampling time point corresponding to the j-th data sampling point and the sampling time point corresponding to the j+1-th data sampling point; Indicates the reverse midpoint of the variation trend curve between the sampling time point corresponding to the j-1th data sampling point and the sampling time point corresponding to the jth data sampling point; represents the derivative value at the positive midpoint; represents the derivative value at the reverse midpoint.

[0039] Specifically, S5 further includes the following specific steps:

[0040] S53: Dynamically control the sampling frequency of the high-speed camera array according to the second sampling effectiveness to obtain a second adjustment frequency p12, wherein the acquisition strategy of the second adjustment frequency is:

[0041] pl2=e2×pl1.

[0042] In addition, the present invention provides a lithium battery thermal runaway eruption dynamics parameter measurement system including the following modules:

[0043] Camera use control module, model building module, first adjustment frequency acquisition module, change trend curve drawing module, second adjustment frequency acquisition module, dynamic parameter measurement module;

[0044] The camera control module uses an infrared camera to monitor the temperature distribution on the surface of the lithium battery in real time, and dynamically controls the use state of the high-speed camera array according to the temperature distribution on the surface of the lithium battery;

[0045] The model building module is used to extract battery status data of the lithium battery under thermal runaway eruption state captured by the high-speed camera array, and to build a dynamic field model and a thermal distribution model of the lithium battery under thermal runaway eruption based on the battery status data;

[0046] The first adjustment frequency acquisition module is used to extract dynamic characteristic data from the dynamic field model, calculate a first sampling validity based on the dynamic characteristic data, and adjust the initial sampling frequency of the high-speed camera array based on the first sampling validity to obtain a first adjustment frequency;

[0047] The change trend curve drawing module is used to extract the thermodynamic characteristic data in the thermal distribution model, calculate the lithium battery ejection coefficient during the battery thermal runaway eruption process in real time, and draw a change trend curve of the lithium battery ejection coefficient during the lithium battery thermal runaway eruption process as a function of the eruption time based on the thermodynamic characteristic data;

[0048] The second adjustment frequency acquisition module is used to mark the data sampling points of the high-speed camera array in the trend curve of the change of the lithium battery injection coefficient with the ejection time, monitor the change trend curve in real time, evaluate the second sampling effectiveness of the high-speed camera array, and dynamically control the sampling frequency of the high-speed camera array according to the second sampling effectiveness to obtain the second adjustment frequency;

[0049] The kinetic parameter measurement module is used to maintain the second adjustment frequency to measure the uncontrolled eruption process of the lithium battery.

[0050] Compared with the prior art, the technical effects of the present invention are as follows:

[0051] 1. The present invention uses an infrared camera to monitor the temperature distribution on the surface of the lithium battery in real time and dynamically controls the use status of the high-speed camera array. This enables the camera to adjust the shooting angle and position in real time, thereby improving the accuracy of capturing the eruption point. Even if the eruption point is uncertain, the camera system can still stay in the key area through dynamic adjustment, ensuring that key data of the eruption process is accurately recorded, reducing data loss caused by the randomness of the eruption point.

[0052] 2. The present invention constructs a dynamic field model and a thermal distribution model based on battery status data, extracts dynamic characteristic data, and dynamically adjusts the sampling frequency, which can adapt to changes in the eruption speed in real time, ensuring that the changing trend of the eruption speed can be accurately captured during high-speed eruption, and avoiding the problem of inaccurate data caused by insufficient or excessive sampling frequency in traditional methods.

[0053] 3. The present invention marks data sampling points in the changing trend curve and evaluates the sampling effectiveness in real time. The sampling frequency of the high-speed camera array is dynamically controlled according to the sampling effectiveness, and the dynamic adjustment of the sampling frequency is optimized, so that key data can be accurately recorded at each stage of the eruption process, which is conducive to the subsequent comprehensive sampling of data at the peak inflection point of the changing trend curve, ensuring the comprehensiveness and accuracy of the data while avoiding excessive data processing load. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0055] in:

[0056] Figure 1 A schematic flow chart of a method for measuring dynamic parameters of thermal runaway eruption of a lithium battery according to the present invention;

[0057] Figure 2 This is a schematic structural diagram of a lithium battery thermal runaway eruption dynamics parameter measurement system according to the present invention;

[0058] Figure 3 This is an example diagram of the four eruption stages of a lithium battery eruption process of the present invention;

[0059] Figure 4 This is a temperature trend comparison curve of the surface temperature of two lithium batteries of the same type under the same eruption environment during the eruption process as a function of the eruption time in an embodiment of the present invention;

[0060] Figure 5 Schematic diagram of the process of drawing a trend curve of the ejection coefficient of the lithium battery according to the present invention as a function of the ejection time;

[0061] Figure numerals: 101, the dividing line between the first eruption stage and the second eruption stage of the lithium battery; 102, the dividing line between the second eruption stage and the third eruption stage of the lithium battery; 103, the dividing line between the third eruption stage and the fourth eruption stage of the lithium battery. DETAILED DESCRIPTION

[0062] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0063] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0064] Secondly, the term "one embodiment" or "embodiment" herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in various places throughout this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive of other embodiments.

[0065] Example 1

[0066] like Figure 1 、 Figure 5 As shown, a method for measuring the dynamic parameters of thermal runaway eruption of a lithium battery according to an embodiment of the present invention is as follows: Figure 1 As shown, the specific steps are as follows:

[0067] S1: Use an infrared camera to monitor the temperature distribution on the surface of the lithium battery in real time, and dynamically control the use status of the high-speed camera array based on the temperature distribution on the surface of the lithium battery;

[0068] In S1, the use of an infrared camera to monitor the temperature distribution on the surface of a lithium battery in real time specifically includes: obtaining temperature distribution image data on the surface of the lithium battery, and grayscale processing the temperature distribution image data, presetting the maximum grayscale threshold and the minimum grayscale threshold corresponding to the uncontrolled eruption temperature, screening the pixel points in the temperature distribution image that are within the maximum grayscale threshold and the minimum grayscale threshold, and calibrating the pixel area obtained by screening as the key monitoring area for uncontrolled eruption of lithium batteries.

[0069] In S1, the use status of the high-speed camera array is dynamically controlled according to the temperature distribution on the surface of the lithium battery, specifically including: extracting the key monitoring area of ​​the uncontrolled eruption of the lithium battery, and controlling the four high-speed cameras through the electric pan-tilt head to keep them in the on state, wherein the first high-speed camera is set to be directly aimed at the front of the lithium battery to capture the main front area of ​​the lithium battery uncontrolled eruption; the second high-speed camera is set to be on the left side of the lithium battery to capture the main area of ​​the left side of the lithium battery uncontrolled eruption; the third high-speed camera is set to be on the right side of the lithium battery to capture the main area of ​​the right side of the lithium battery uncontrolled eruption; the fourth high-speed camera is set to be directly above the lithium battery to capture the overhead sub-area of ​​the uncontrolled eruption of the lithium battery.

[0070] S2: Extract the battery status data of the lithium battery under thermal runaway eruption captured by the high-speed camera array, and construct the dynamic field model and thermal distribution model under the thermal runaway eruption of the lithium battery based on the battery status data;

[0071] The battery status data in S2 includes: real-time eruption speed data, eruption area length data, eruption angle data and eruption morphology data, lithium battery surface temperature data, heat flux density data, thermal diffusivity and convective heat transfer coefficient;

[0072] The dynamic field model in S2 includes: real-time eruption velocity data, eruption area length data, eruption angle data, and eruption morphology data;

[0073] The thermal distribution model in S2 includes: lithium battery surface temperature data, heat flux density data, thermal diffusivity and convection heat transfer coefficient.

[0074] S3: extracting dynamic characteristic data from the dynamic field model, calculating a first sampling validity based on the dynamic characteristic data, and adjusting an initial sampling frequency of the high-speed camera array based on the first sampling validity to obtain a first adjusted frequency;

[0075] In S3, the calculation strategy of the first sampling validity e1 is specifically as follows:

[0076]

[0077] Among them, in the main frontal area of ​​the battery uncontrolled eruption, the length of the eruption area is divided into one meter as a sampling validity unit analysis distance, and a total of X sampling validity unit analysis distances are obtained, where x is the subscript, indicating the xth sampling validity unit analysis distance;

[0078] v x ,v x-1 ,v x+1 The real-time eruption speed of lithium batteries in the x-th, x-1th and x+1th sampling validity units are analyzed respectively;

[0079] The mean of the real-time ejection velocity of the lithium battery in the analysis distance for X sampling validity units.

[0080] In S3, the calculation strategy of the first adjustment frequency pl1 is specifically:

[0081] pl1=e1×pl0;

[0082] Where p10 is the initial sampling frequency of the high-speed camera array.

[0083] S4: extracting thermodynamic characteristic data from the thermal distribution model, calculating the lithium battery ejection coefficient during the battery thermal runaway eruption process in real time, and drawing a trend curve of the lithium battery ejection coefficient during the lithium battery thermal runaway eruption process versus the eruption time based on the thermodynamic characteristic data;

[0084] like Figure 5 As shown, S4 includes the following specific steps:

[0085] S41: extracting thermodynamic characteristic data from the thermal distribution model;

[0086] S42: Real-time calculation of the lithium battery ejection coefficient ps during the battery thermal runaway ejection process. The calculation strategy of the lithium battery ejection coefficient is as follows:

[0087] ps=∫∫∫(ε1×Q1+ε2×Q2)dW;

[0088] Where W is the unit volume of the monitoring enclosed space for thermal runaway eruption of lithium batteries;

[0089] ε1 and ε2 are the combustion heat ratio coefficient and the convection heat ratio coefficient respectively;

[0090] Q1 is the combustion heat released by the thermal runaway eruption of the lithium battery into the monitored enclosed space;

[0091] Q1 = ln[R′(t) + 2.32], where R′(t) is the heat function of the lithium battery thermal runaway eruption;

[0092] For example, in this embodiment, an expression of the heat function of thermal runaway eruption of a lithium battery is given: R′(t)=n djy ×ΔH fj +n Li ×ΔH rs , n djy is the number of moles of sprayed electrolyte in the electrolyte; ΔH fj is the enthalpy change of the electrolyte decomposition at high temperature; n Li is the number of moles of lithium metal; ΔH rs is the enthalpy change of the lithium metal combustion reaction;

[0093] Q2 is the heat generated by thermal convection between the air and the lithium battery in the enclosed space during the thermal runaway eruption of the lithium battery; S ldc is the surface area of ​​the lithium battery; Te max ,Te min The maximum and minimum temperatures on the surface of the lithium battery during the thermal runaway eruption of the lithium battery; are the average surface temperature of the lithium battery and the average air temperature in the monitored enclosed space during the thermal runaway eruption of the lithium battery; hc is the convective heat transfer coefficient;

[0094] For example, in this embodiment, a strategy for determining the convective heat transfer coefficient hc is provided. The specific strategy includes:

[0095]

[0096] Wherein, dr is the thermal conductivity of lithium battery electrolyte;

[0097] lm is the dimensionless value of the farthest eruption distance of the lithium battery;

[0098] Re is the Reynolds number; ρ is the heat flux density of the lithium battery electrolyte, μ is the viscosity of the electrolyte, and L is the length of the eruption area of ​​the lithium battery;

[0099] Pr is the Prandtl number; γ is the thermal diffusivity; σ is the dynamic viscosity of the lithium battery electrolyte,

[0100] S43: Draw a trend curve of the lithium battery ejection coefficient during the thermal runaway eruption process of the lithium battery as a function of the eruption time.

[0101] S5: Marking data sampling points of the high-speed camera array in the trend curve of the change of the lithium battery ejection coefficient with the ejection time, monitoring the change trend curve in real time, evaluating the second sampling effectiveness of the high-speed camera array, and dynamically controlling the sampling frequency of the high-speed camera array according to the second sampling effectiveness to obtain a second adjustment frequency;

[0102] S5 includes the following specific steps:

[0103] S51: In the trend curve of the lithium battery ejection coefficient versus ejection time, mark the data sampling points of the high-speed camera array and obtain the data sampling point set {A1, A2...A j ...A J}, where j is a subscript, indicating the jth data sampling point of the high-speed camera array, and J is the total number of data sampling points; A j Indicates the sampling time point corresponding to the j-th data sampling point;

[0104] S52: Monitor the change trend curve in real time and evaluate the second sampling effectiveness e2 of the high-speed camera array. The calculation strategy of the second sampling effectiveness is specifically as follows:

[0105]

[0106] Among them, g′ j ,g′ j-1 ,g′ j+1 Respectively represent the derivative values ​​of the change trend curve at the jth, j-1th and j+1th data sampling points; Indicates the positive midpoint of the change trend curve between the sampling time point corresponding to the j-th data sampling point and the sampling time point corresponding to the j+1-th data sampling point; Indicates the reverse midpoint of the variation trend curve between the sampling time point corresponding to the j-1th data sampling point and the sampling time point corresponding to the jth data sampling point; represents the derivative value at the positive midpoint; represents the derivative value at the reverse midpoint.

[0107] S5 also includes the following specific steps:

[0108] S53: Dynamically control the sampling frequency of the high-speed camera array according to the second sampling effectiveness to obtain a second adjustment frequency p12, wherein the acquisition strategy of the second adjustment frequency is:

[0109] pl2=e2×pl1.

[0110] S6: Maintain the second adjustment frequency to measure the uncontrolled eruption process of the lithium battery.

[0111] Example 2

[0112] like Figure 2 As shown, a lithium battery thermal runaway eruption dynamics parameter measurement system according to an embodiment of the present invention is as follows: Figure 2 As shown, it includes the following modules:

[0113] Camera use control module, model building module, first adjustment frequency acquisition module, change trend curve drawing module, second adjustment frequency acquisition module, dynamic parameter measurement module;

[0114] The camera control module uses an infrared camera to monitor the temperature distribution on the surface of the lithium battery in real time, and dynamically controls the use state of the high-speed camera array according to the temperature distribution on the surface of the lithium battery;

[0115] The model building module is used to extract battery status data of the lithium battery under thermal runaway eruption state captured by the high-speed camera array, and to construct a dynamic field model and a thermal distribution model of the lithium battery under thermal runaway eruption according to the dynamics of the battery status data;

[0116] The first adjustment frequency acquisition module is used to extract dynamic characteristic data from the dynamic field model, calculate a first sampling validity based on the dynamic characteristic data, and adjust the initial sampling frequency of the high-speed camera array based on the first sampling validity to obtain a first adjustment frequency;

[0117] The change trend curve drawing module is used to extract the thermodynamic characteristic data in the thermal distribution model, calculate the lithium battery ejection coefficient during the battery thermal runaway eruption process in real time, and draw a change trend curve of the lithium battery ejection coefficient during the lithium battery thermal runaway eruption process as a function of the eruption time based on the thermodynamic characteristic data;

[0118] The second adjustment frequency acquisition module is used to mark the data sampling points of the high-speed camera array in the trend curve of the change of the lithium battery injection coefficient with the ejection time, monitor the change trend curve in real time, evaluate the second sampling effectiveness of the high-speed camera array, and dynamically control the sampling frequency of the high-speed camera array according to the second sampling effectiveness to obtain the second adjustment frequency;

[0119] The kinetic parameter measurement module is used to maintain the second adjustment frequency to measure the uncontrolled eruption process of the lithium battery.

[0120] Example 3

[0121] For example, in this embodiment, a specific implementation of the technical solution of the method for measuring the dynamic parameters of thermal runaway eruption of a lithium battery as described above is provided, including:

[0122] In this embodiment, the surface temperature of two lithium batteries of the same type during the eruption process under the same eruption environment is sampled using the technical solution of the above-mentioned method for measuring the dynamic parameters of thermal runaway eruption of lithium batteries.

[0123] Among them, Figure 3 As shown, the eruption of lithium batteries mainly includes: the first eruption stage, the second eruption stage, the third eruption stage and the fourth eruption stage;

[0124] During the first eruption stage, the electrolyte inside the lithium battery heats up and is in the eruption preparation stage. During the first eruption stage, the surface temperature of the lithium battery slowly rises;

[0125] In the second eruption stage, the electrolyte inside the lithium battery erupts rapidly, and the surface temperature of the lithium battery rises rapidly in the second eruption stage;

[0126] In the third eruption stage, the electrolyte inside the lithium battery gradually erupts and is exhausted. In the third eruption stage, the surface temperature of the lithium battery shows a downward trend.

[0127] The lithium battery eruption is completed in the fourth eruption stage, and the surface temperature of the lithium battery is in a gradually stable trend in the fourth eruption stage;

[0128] Furthermore, if Figure 4 As shown, the temperature trend comparison curves corresponding to the two lithium batteries are drawn according to the surface temperature of the lithium battery during the lithium battery eruption process;

[0129] according to Figure 4 As shown, according to the technical solution of the method for measuring the dynamic parameters of thermal runaway eruption of a lithium battery described above, during the eruption process of two lithium batteries of the same type under the same eruption environment, the sampling frequency of the high-speed camera array can be dynamically controlled by sampling effectiveness so that the peak inflection point time of the two temperature trend curves during the eruption process of the two lithium batteries tends to be consistent; it shows that the technical solution of the method for measuring the dynamic parameters of thermal runaway eruption of a lithium battery described above can adapt to the changes in the eruption speed in real time with small error, ensuring that the changing trend of the eruption speed can be accurately captured during the high-speed eruption process, avoiding the problem of inaccurate data caused by insufficient or too fast sampling frequency in the key sampling stage in traditional methods.

[0130] It should be understood that in the various embodiments of the present application, the size of the serial numbers of the above-mentioned processes does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0131] It should be understood that determining B based on A does not mean determining B only based on A. B can also be determined based on A and / or other information.

[0132] The above embodiments can be implemented in whole or in part through software, hardware, firmware, or any other combination. When implemented using software, the above embodiments can be implemented in whole or in part in the form of a computer program product. A computer program product includes one or more computer instructions or computer programs. When the computer instructions or computer program are loaded or executed on a computer, the processes or functions according to the embodiments of the present invention are generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via a wired network or / and a wireless network. The computer-readable storage medium can be any available medium that can be accessed by a computer or a data storage device such as a server or data center that contains a collection of one or more available media. The available media can be magnetic media (e.g., floppy disks, hard disks, tapes), optical media (e.g., DVDs), or semiconductor media. The semiconductor media can be a solid-state drive.

[0133] Those skilled in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed in the present invention can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professionals and technicians can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of the present invention.

[0134] Those skilled in the art will clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0135] In the several embodiments provided by the present invention, it should be understood that the disclosed systems, devices, and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For example, the division of units is only one type. In actual implementation, there may be other division methods, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0136] Units described as separate components may or may not be physically separate, and components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of these units may be selected to achieve the purpose of this embodiment according to actual needs.

[0137] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0138] Throughout this specification, references to terms such as "one embodiment," "example," or "specific example" indicate that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0139] In summary, compared with the prior art, the technical effects of the present invention are as follows:

[0140] 1. The present invention uses an infrared camera to monitor the temperature distribution on the surface of the lithium battery in real time and dynamically controls the use status of the high-speed camera array. This enables the camera to adjust the shooting angle and position in real time, thereby improving the accuracy of capturing the eruption point. Even if the eruption point is uncertain, the camera system can still stay in the key area through dynamic adjustment, ensuring that key data of the eruption process is accurately recorded, reducing data loss caused by the randomness of the eruption point.

[0141] 2. The present invention constructs a dynamic field model and a thermal distribution model based on battery status data, extracts dynamic characteristic data, and dynamically adjusts the sampling frequency, which can adapt to changes in the eruption speed in real time, ensuring that the changing trend of the eruption speed can be accurately captured during high-speed eruption, and avoiding the problem of inaccurate data caused by insufficient or excessive sampling frequency in traditional methods.

[0142] 3. The present invention marks data sampling points in the changing trend curve and evaluates the sampling effectiveness in real time. The sampling frequency of the high-speed camera array is dynamically controlled according to the sampling effectiveness, and the dynamic adjustment of the sampling frequency is optimized, so that key data can be accurately recorded at each stage of the eruption process, which is conducive to the subsequent comprehensive sampling of data at the peak inflection point of the changing trend curve, ensuring the comprehensiveness and accuracy of the data while avoiding excessive data processing load.

[0143] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for measuring the dynamic parameters of thermal runaway eruption of a lithium battery, characterized by: The method comprises the following specific steps: S1: Use an infrared camera to monitor the temperature distribution on the surface of the lithium battery in real time, and dynamically control the use status of the high-speed camera array based on the temperature distribution on the surface of the lithium battery; S2: Extract the battery status data of the lithium battery under thermal runaway eruption captured by the high-speed camera array, and construct the dynamic field model and thermal distribution model under the thermal runaway eruption of the lithium battery based on the battery status data; S3: extracting dynamic characteristic data from the dynamic field model, calculating a first sampling validity based on the dynamic characteristic data, and adjusting an initial sampling frequency of the high-speed camera array based on the first sampling validity to obtain a first adjusted frequency; S4: extracting thermodynamic characteristic data from the thermal distribution model, calculating the lithium battery ejection coefficient during the battery thermal runaway eruption process in real time, and drawing a trend curve of the lithium battery ejection coefficient during the eruption process versus the eruption time based on the thermodynamic characteristic data; S5: Marking data sampling points of the high-speed camera array in the trend curve of the change of the lithium battery ejection coefficient with the ejection time, monitoring the change trend curve in real time, evaluating the second sampling effectiveness of the high-speed camera array, and dynamically controlling the sampling frequency of the high-speed camera array according to the second sampling effectiveness to obtain a second adjustment frequency; S6: Maintain the second adjustment frequency to measure the uncontrolled eruption process of the lithium battery.

2. The method for measuring the thermal runaway eruption dynamics parameters of a lithium battery according to claim 1, characterized in that: In S1, the use of an infrared camera to monitor the temperature distribution on the surface of a lithium battery in real time specifically includes: obtaining temperature distribution image data on the surface of the lithium battery, and grayscale processing the temperature distribution image data, presetting the maximum grayscale threshold and the minimum grayscale threshold corresponding to the uncontrolled eruption temperature, screening the pixel points in the temperature distribution image that are within the maximum grayscale threshold and the minimum grayscale threshold, and calibrating the pixel area obtained by screening as the key monitoring area for uncontrolled eruption of lithium batteries.

3. The method for measuring the thermal runaway eruption dynamics parameters of a lithium battery according to claim 2, characterized in that: In S1, the use status of the high-speed camera array is dynamically controlled according to the temperature distribution on the surface of the lithium battery, specifically including: extracting the key monitoring area of ​​the uncontrolled eruption of the lithium battery, and controlling the four high-speed cameras through the electric pan-tilt head to keep them in the on state, wherein the first high-speed camera is set to be directly aimed at the front of the lithium battery to capture the main front area of ​​the lithium battery uncontrolled eruption; the second high-speed camera is set to the left side of the lithium battery to capture the main area of ​​the left side of the lithium battery uncontrolled eruption; the third high-speed camera is set to the right side of the lithium battery to capture the main area of ​​the right side of the lithium battery uncontrolled eruption; the fourth high-speed camera is set to be directly above the lithium battery to capture the overhead sub-area of ​​the uncontrolled eruption of the lithium battery.

4. The method for measuring the thermal runaway eruption dynamics parameters of a lithium battery according to claim 3, characterized in that: The dynamic field model described in S2 includes: real-time eruption velocity data, eruption area length data, eruption angle data and eruption morphology data; the thermal distribution model described in S2 includes: lithium battery surface temperature data, heat flux density data, thermal diffusivity and convective heat transfer coefficient.

5. The method for measuring the thermal runaway eruption dynamics parameters of a lithium battery according to claim 4, characterized in that: In S3, the calculation strategy of the first sampling validity e1 is specifically as follows: Among them, in the main front area of ​​the battery uncontrolled eruption, the length of the eruption area is divided into one meter as a sampling validity unit analysis distance, and a total of X sampling validity unit analysis distances are obtained, where x is the subscript, indicating the xth sampling validity unit analysis distance; v x ,v x-1 ,v x+1 The real-time eruption speed of lithium batteries in the x-th, x-1th and x+1th sampling validity units are analyzed respectively; The mean of the real-time ejection velocity of the lithium battery in the analysis distance for X sampling validity units.

6. The method for measuring the thermal runaway eruption dynamics parameters of a lithium battery according to claim 5, characterized in that: In S3, the calculation strategy of the first adjustment frequency pl1 is specifically: pl1=e1×pl0; Where p10 is the initial sampling frequency of the high-speed camera array.

7. The method for measuring the thermal runaway eruption dynamics parameters of a lithium battery according to claim 6, characterized in that: S4 includes the following specific steps: S41: extracting thermodynamic characteristic data from the thermal distribution model; S42: Real-time calculation of the lithium battery ejection coefficient ps during the battery thermal runaway ejection process. The calculation strategy of the lithium battery ejection coefficient is as follows: ps=∫∫∫(ε1×Q1+ε2×Q2)dW; Where W is the unit volume of the monitoring enclosed space for thermal runaway eruption of lithium batteries; ε1 and ε2 are the combustion heat ratio coefficient and the convection heat ratio coefficient respectively; Q1 is the combustion heat released by the thermal runaway eruption of the lithium battery into the monitored enclosed space; Q1 = ln[R′(t) + 2.32], where R′(t) is the heat function of the lithium battery thermal runaway eruption; Q2 is the heat generated by thermal convection between the air and the lithium battery in the enclosed space during the thermal runaway eruption of the lithium battery; S ldc is the surface area of ​​the lithium battery; Te max ,Te min The maximum and minimum temperatures on the surface of the lithium battery during the thermal runaway eruption of the lithium battery; are the average surface temperature of the lithium battery and the average air temperature in the monitored enclosed space during the thermal runaway eruption of the lithium battery; hc is the convective heat transfer coefficient; S43: Draw a trend curve of the lithium battery ejection coefficient during the thermal runaway eruption process of the lithium battery as a function of the eruption time.

8. The method for measuring the thermal runaway eruption dynamics parameters of a lithium battery according to claim 7, characterized in that: S5 includes the following specific steps: S51: In the trend curve of the lithium battery ejection coefficient versus ejection time, mark the data sampling points of the high-speed camera array and obtain the data sampling point set {A1, A2...A j ...A J }, where j is a subscript, indicating the jth data sampling point of the high-speed camera array, and J is the total number of data sampling points; A j Indicates the sampling time point corresponding to the j-th data sampling point; S52: Monitor the change trend curve in real time and evaluate the second sampling effectiveness e2 of the high-speed camera array. The calculation strategy of the second sampling effectiveness is specifically as follows: Among them, g′ j ,g′ j-1 ,g′ j+1 Respectively represent the derivative values ​​of the change trend curve at the jth, j-1th and j+1th data sampling points; Indicates the positive midpoint of the change trend curve between the sampling time point corresponding to the j-th data sampling point and the sampling time point corresponding to the j+1-th data sampling point; Indicates the reverse midpoint of the variation trend curve between the sampling time point corresponding to the j-1th data sampling point and the sampling time point corresponding to the jth data sampling point; represents the derivative value at the positive midpoint; represents the derivative value at the reverse midpoint.

9. The method for measuring the thermal runaway eruption dynamics parameters of a lithium battery according to claim 8, characterized in that: S5 also includes the following specific steps: S53: Dynamically control the sampling frequency of the high-speed camera array according to the second sampling effectiveness to obtain a second adjustment frequency p12, wherein the acquisition strategy of the second adjustment frequency is: pl2=e2×pl1.

10. A lithium battery thermal runaway eruption dynamics parameter measurement system, used to implement a lithium battery thermal runaway eruption dynamics parameter measurement method according to any one of claims 1 to 9, characterized in that: The system includes the following modules: Camera use control module, model building module, first adjustment frequency acquisition module, change trend curve drawing module, second adjustment frequency acquisition module, dynamic parameter measurement module; The camera control module uses an infrared camera to monitor the temperature distribution on the surface of the lithium battery in real time, and dynamically controls the use state of the high-speed camera array according to the temperature distribution on the surface of the lithium battery; The model building module is used to extract battery status data of the lithium battery under thermal runaway eruption state captured by the high-speed camera array, and to construct a dynamic field model and a thermal distribution model of the lithium battery under thermal runaway eruption according to the dynamics of the battery status data; The first adjustment frequency acquisition module is used to extract dynamic characteristic data from the dynamic field model, calculate a first sampling validity based on the dynamic characteristic data, and adjust the initial sampling frequency of the high-speed camera array based on the first sampling validity to obtain a first adjustment frequency; The change trend curve drawing module is used to extract the thermodynamic characteristic data in the thermal distribution model, calculate the lithium battery ejection coefficient during the battery thermal runaway eruption process in real time, and draw a change trend curve of the lithium battery ejection coefficient during the lithium battery thermal runaway eruption process as a function of the eruption time based on the thermodynamic characteristic data; The second adjustment frequency acquisition module is used to mark the data sampling points of the high-speed camera array in the trend curve of the change of the lithium battery injection coefficient with the ejection time, monitor the change trend curve in real time, evaluate the second sampling effectiveness of the high-speed camera array, and dynamically control the sampling frequency of the high-speed camera array according to the second sampling effectiveness to obtain the second adjustment frequency; The kinetic parameter measurement module is used to maintain the second adjustment frequency to measure the uncontrolled eruption process of the lithium battery.

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