A multi-parameter early warning method and system for battery overheat runaway

Abstract

The application provides a multi-parameter early warning method and system for battery overheat runaway, and the early warning method comprises the following steps: collecting measurement values of multiple parameters of a battery, wherein the parameters include voltage, temperature and surface pressure of the battery; processing the measurement values of various parameters to obtain processing values of various parameters; and determining an overheat runaway early warning level of the battery through a multi-parameter coupling overheat runaway early warning level criterion based on the measurement values and the processing values. The multi-parameter early warning method and system for battery overheat runaway provided by the application can determine key characteristic parameters for predicting the overheat runaway level of the battery based on the coupling relationship between multiple parameters of the battery in the overheat runaway process, and provide accurate early warning for the overheat runaway process of the battery.

Description

Technical Field

[0001] This application belongs to the field of battery safety testing technology, specifically, it provides a multi-parameter early warning method and system for battery overheating runaway. Background Technology

[0002] Electric vehicles, as a representative of new energy vehicle technology, have achieved rapid development in recent years, and the level of attention to the safety of electric vehicles is also increasing. Various rechargeable batteries that serve as the power source for electric vehicles, such as lithium-ion batteries, lithium iron phosphate batteries, and ternary lithium-ion batteries, may experience overheating and runaway in the event of various emergencies, and may even cause fires. Because the incidents happen suddenly, it is difficult for vehicles and vehicle users to receive warnings before battery problems occur. Therefore, it is essential to provide early warnings based on the mechanism of battery thermal runaway.

[0003] Currently, there are various methods for monitoring and warning of battery overheating runaway. For example, Gao Fei et al. (Gao Fei, Yang Kai, Wang Kangkang, Wang Songcen, Zhuang Mingzhao. Design and verification of lithium-ion battery safety early warning and protection system [J]. Electronic Design Engineering, 2019, 27(01): 1-4.) used a highly sensitive temperature sensor, combined with the characteristics of lithium-ion batteries during combustion, and integrated multiple sensors such as smoke and infrared flame sensors to design a thermal runaway early warning system. When the relevant parameters exceed the threshold, a graded early warning can be issued. Deng Yuanbing (Deng Yuanbing. Experimental and simulation study on thermal runaway and its early warning mechanism of lithium-ion power battery [D]. Huazhong University of Science and Technology, 2017.) used the voltage, temperature and current signals collected by the battery management system (BMS) to issue a thermal runaway early warning. When the temperature change rate reaches the threshold, an alarm is issued. When the threshold is not reached, the appropriate type of thermal runaway model is selected according to the signal characteristics, the remaining time of thermal runaway is calculated, and feedback is given to the driver.

[0004] Current battery overheat runaway early warning methods mostly use voltage and temperature data, and mainly determine the overheat runaway level by the segmented intervals of voltage and temperature. Since various battery parameters are mutually coupled during the overheat runaway process, and the changes of each parameter are simultaneously affected by multiple other parameters, batteries of different models and specifications may be in completely different overheat runaway stages even in the same segmented interval. Therefore, simply judging the early warning level based on the segmented interval has certain problems in terms of prediction accuracy and robustness. Summary of the Invention

[0005] To address the problems existing in the prior art, the purpose of this application is to provide a multi-parameter early warning method and system for battery overheating runaway. Based on a comprehensive consideration of the mutual coupling and influence effects between multiple parameters during battery overheating runaway, it can provide accurate early warning for overheating runaway of various battery models.

[0006] On the one hand, this application provides a multi-parameter early warning method for battery overheating runaway through embodiments, including the following steps:

[0007] The system collects measurements of various parameters of the battery, including the battery's voltage, temperature, and surface pressure.

[0008] The measured values ​​of various parameters are processed to obtain the processed values ​​of various parameters;

[0009] Based on the measured and processed values, the overheating runaway warning level of the battery is determined by a multi-parameter coupled overheating runaway warning level criterion.

[0010] Furthermore, the processed values ​​include: the first and second derivatives of the voltage measurement with respect to time, the first and second derivatives of the temperature measurement with respect to time, and the pressure state change vector.

[0011] Furthermore, the pressure state transition vector is [P_, P, N], where P_ is the pressure state of the battery surface at the previous measurement time, P is the pressure state of the battery surface at the current measurement time, and N is the cumulative number of pressure state transitions on the battery surface; when the battery surface pressure is less than a preset pressure threshold, the pressure state is zero, otherwise the pressure state is non-zero.

[0012] Furthermore, the criteria for determining the overheating runaway warning level are determined through the following steps:

[0013] S1, Obtain experimental data on overheating runaway of multiple batteries of the same model;

[0014] S2, extract the overheating runaway experimental data of any battery, and perform the following steps in sequence:

[0015] S21, Extract the measured and processed values ​​of each parameter of the battery at each measurement time;

[0016] S22, determine the arrival time of multiple parameter characteristic values ​​of the battery during the overheat runaway process;

[0017] S23, extract the state of charge of the battery at the arrival time of each parameter characteristic value and the difference between the state of charge and the state of charge when the overheating runaway occurs.

[0018] S24, extract the overheat runaway experimental data of another battery of the same model and return to step S21, until all experimental data are traversed;

[0019] S3, Based on the data extracted in step S2, perform correlation mining to obtain the importance of each parameter feature value;

[0020] S4. Based on the importance of each parameter feature value, select a specific parameter feature value to construct a multi-parameter coupled overheat runaway early warning level criterion corresponding to the battery model.

[0021] Preferably, the parameter characteristics include multiple characteristic voltages, multiple characteristic temperatures, and multiple characteristic pressures.

[0022] Preferably, the plurality of characteristic voltages include: the voltage when the voltage reaches its peak value for the first time under overcharge conditions, the voltage when the first derivative of the voltage with respect to time changes from positive to negative for the second time under overcharge conditions, and the voltage when the voltage suddenly increases during the decreasing phase under overcharge conditions and then decreases again within a certain period of time.

[0023] Preferably, the plurality of characteristic temperatures include: the temperature at which the temperature changes by more than 5°C for the first time under overcharge conditions and the rate of temperature change exceeds 0.1°C / s, and the temperature at which the second derivative of temperature with respect to time changes from a positive value to a negative value.

[0024] Preferably, the plurality of characteristic pressures include: pressure state change vectors with vector values ​​of [zero state, non-zero state, 1], [non-zero state, zero state, 2], and [zero state, non-zero state, 3], respectively.

[0025] Preferably, the multi-parameter early warning method for battery overheating runaway further includes the following step: estimating the time difference between when the battery reaches its current overheating runaway warning level and when overheating runaway occurs.

[0026] On the other hand, this application also provides a multi-parameter early warning system for battery overheating runaway through embodiments, including:

[0027] The acquisition unit is used to acquire measured values ​​of various parameters of the battery, including the battery's voltage, temperature, and surface pressure.

[0028] The processing unit is used to process the measured value of each parameter to obtain the processed value of that parameter;

[0029] The judgment unit determines the overheating runaway warning level of the battery based on the measured and processed values ​​through a multi-parameter coupled overheating runaway warning level criterion.

[0030] The multi-parameter early warning method and system for battery overheating runaway provided in the embodiments of this application determine key characteristic parameters based on the coupling relationship between multiple characteristic voltages, characteristic temperatures, and characteristic pressures during the battery overheating runaway process, and establish a multi-parameter coupled overheating runaway early warning level criterion. This effectively solves the problem that single-dimensional parameter characteristic values ​​cannot completely and accurately reflect the state changes experienced by the battery during the overheating runaway process, and effectively improves the accuracy and effectiveness of battery overheating runaway early warning. Attached Figure Description

[0031] Figure 1 This is a flowchart illustrating a multi-parameter early warning method for battery overheating runaway provided according to an embodiment of this application;

[0032] Figure 2 This is a schematic diagram illustrating the changes in voltage and rate of voltage change over time for a specific battery during its overheating runaway process.

[0033] Figure 3 This is a schematic diagram illustrating how the temperature and rate of temperature change change over time in a specific battery during its overheating runaway process.

[0034] Figure 4 This is a schematic diagram illustrating the change in surface pressure over time in a specific battery during its overheating runaway process.

[0035] Figure 5 A flowchart illustrating the process of constructing a multi-parameter coupled overheat runaway early warning level criterion corresponding to a specific battery model;

[0036] Figure 6 This is a schematic diagram illustrating the correlation between the feature values ​​of various parameters obtained using the Apriori algorithm and the importance evaluation index in a specific embodiment.

[0037] Figure 7 This is a flowchart illustrating a multi-parameter early warning method for battery overheating runaway provided according to an embodiment of this application;

[0038] Figure 8 This describes the response of various parameters after the battery enters a first-level warning state in a specific battery overheating runaway experiment.

[0039] Figure 9 This describes the response of various parameters after the battery enters a secondary warning state in a specific battery overheating runaway experiment.

[0040] Figure 10 This describes the response of various parameters after the battery enters a level 3 warning state in a specific battery overheating runaway experiment.

[0041] Figure 11 This describes the response of various parameters after the battery enters a level 4 warning state in a specific battery overheating runaway experiment.

[0042] Figure 12 This is a schematic diagram of the framework of a multi-parameter early warning system for battery overheating runaway provided according to an embodiment of this application. Detailed Implementation

[0043] The present application will now be further described based on preferred embodiments and with reference to the accompanying drawings. The embodiments described below are merely some, not all, embodiments of the present application, and should not be construed as limiting the scope of the technical solutions claimed in this application.

[0044] Furthermore, the terms used in this specification, such as “comprising,” “having,” and their cognates, are used only to indicate a specific feature, variable, value, step, element, or combination thereof, and should not be construed as excluding the possibility of the presence of at least one other feature, variable, value, step, element, or combination thereof; and the terms used in this specification, such as “first” and “second,” are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0045] Unless otherwise specified, the technical and scientific terms used in this specification have the same meanings as commonly understood by one of ordinary skill in the art.

[0046] This application provides a multi-parameter early warning method for battery overheating runaway, used to provide early warning of the battery overheating runaway process. In the specification of this application, the batteries involved in the various embodiments can be various types of batteries such as lithium batteries and ternary lithium batteries that provide power for electric vehicles, or batteries that provide power sources for other types of equipment.

[0047] Figure 1 The flowchart of the early warning method is shown in some preferred embodiments, such as... Figure 1 As shown, the early warning method includes the following steps:

[0048] Step 100: Collect measurement values ​​of various parameters of the battery, including battery voltage, temperature and surface pressure;

[0049] Step 200: Process the measured values ​​of various parameters to obtain the processed values ​​of various parameters;

[0050] Step 300: Based on the measured value and the processed value, determine the overheat runaway warning level of the battery through a multi-parameter coupled overheat runaway warning level criterion.

[0051] The following describes in detail the multi-parameter early warning method for battery overheating runaway provided in this application, based on the accompanying drawings and preferred embodiments.

[0052] Step 100 is used to measure various parameters of the battery. In the embodiments of this application, the parameters include the battery voltage, temperature, and surface pressure. During the overheating runaway process, the battery voltage and temperature often change rapidly with the overheating runaway state, so they are generally used as important parameters for judging the battery state. In addition, for different battery models, their packaging materials and packaging methods are different, resulting in significant differences in the hardness of the battery surface, and different morphological changes occur at different stages of the battery overheating runaway process. Therefore, in the embodiments of this application, the surface pressure of the battery is used as an important parameter, and the measured value of the battery surface pressure is obtained by a pressure sensor set between adjacent battery modules or between the battery surface and its external fixed structure.

[0053] In some specific embodiments, parameters such as battery voltage, temperature, and surface pressure can be continuously measured at certain sampling time intervals, and a sequence of measured values ​​for each of these parameters can be generated according to the sampling time. The aforementioned measurement of battery voltage, temperature, and surface pressure is known to those skilled in the art and will not be elaborated upon here.

[0054] Step 200 further processes the measured values ​​of battery voltage, temperature, and surface pressure to obtain processed values ​​corresponding to the aforementioned parameters. The processed values ​​corresponding to the battery voltage parameter include the first and second derivatives of the voltage measurement with respect to time; the processed values ​​corresponding to the battery temperature parameter include the first and second derivatives of the temperature measurement with respect to time. Specifically, the first derivative of the voltage / temperature measurement with respect to time reflects the rate of change of voltage / temperature, expressed in V / s and ℃ / s, respectively; the second derivative of the voltage / temperature measurement with respect to time reflects the speed of change of the rate of change of voltage / temperature, expressed in V / s. 2 and ℃ / S 2 Units. Figure 2 This is a schematic diagram showing the measured voltage and rate of change of a specific battery over time during its overheating runaway process. Figure 3 This is a schematic diagram showing the temperature measurement and rate of change over time for a specific battery during its overheating runaway process.

[0055] Figure 4 This diagram illustrates the change in surface pressure over time during the thermal runaway of a specific battery. Figure 4 It is evident that the trend of battery surface pressure over time differs significantly from that of voltage and temperature. Specifically, as the overheating runaway process continues, the battery surface pressure experiences drastic abrupt changes at certain points in time, for example, at... Figure 4At the boundary between Zone I and Zone II, the surface pressure of the battery jumps from 0 to a large pressure value in a very short time (corresponding to the sudden bulging of the battery). Then, at the boundary between Zone II and Zone III, the surface pressure value drops sharply (corresponding to the sudden retraction of the battery), and at the boundary between Zone III and Zone IV, another jump in surface pressure occurs (corresponding to the battery suddenly bulging again). These characteristics of battery surface pressure changes make the pressure parameter more distinctive than other parameters, more sensitive to changes in battery state, and more responsive. It is also more cost-effective than other researchers' microsensors. However, at the aforementioned jump points, the rate of change of battery surface pressure will exhibit extreme peaks. Therefore, the conventional method of calculating the rate of change is not suitable for characterizing the surface pressure during battery overheating and runaway.

[0056] Therefore, in the embodiments of this application, a 1×3 pressure state change vector is used as the processing value of the battery surface pressure to characterize the change in battery surface pressure. The specific form of this pressure state change vector is [P_, P, N], where P_ is the pressure state of the battery surface at the previous measurement time, P is the pressure state of the battery surface at the current measurement time, and N is the cumulative number of pressure state changes on the battery surface.

[0057] The surface pressure state can be determined based on the following criterion: when the battery surface pressure is less than a preset pressure threshold, the pressure state is zero; otherwise, the pressure state is non-zero. Using this criterion, the measured values ​​of the battery surface pressure can be binarized, and the pressure state change vector corresponding to each measurement moment can be further obtained. (Continuing with...) Figure 4 For example, (1) in region I of the figure, the value of the pressure state change vector remains [zero state, zero state, 0]; (2) at the moment when the surface pressure jumps upward for the first time (i.e., at the junction of region I and region II), the pressure state change vector is [zero state, non-zero state, 1], and remains [non-zero state, non-zero state, 1] thereafter; (3) at the moment when the surface pressure jumps downward for the first time (i.e., at the junction of region II and region III), the pressure state change vector becomes [non-zero state, zero state, 2], and remains [zero state, zero state, 2] thereafter; (4) at the moment when the surface pressure jumps upward for the second time (i.e., at the junction of region III and region IV), the pressure state change vector becomes [zero state, non-zero state, 3], and remains [non-zero state, non-zero state, 3] thereafter.

[0058] After obtaining the measured and processed values ​​of each parameter through steps 100 and 200 above, step 300 determines the overheat runaway warning level of the battery. In the embodiments of this application, the above determination is performed using a pre-established overheat runaway warning level criterion coupled with multiple parameters corresponding to the specific battery model.

[0059] The following detailed description of the construction process of the multi-parameter coupled overheat runaway early warning level criterion, with reference to specific embodiments, illustrates this process.

[0060] pass Figure 4 It can be seen that during the overheating runaway process of the battery, the surface pressure of the battery undergoes a sudden change in state at certain moments. The value of the pressure state change vector at this moment can be used to characterize some key features of the battery overheating runaway process. For example, in some preferred embodiments of this application, the values ​​of the pressure state change vectors at the junctions of region I and region II, region II and region III, and region III and region IV can be used as characteristic pressures, and respectively designated as characteristic pressure 1, characteristic pressure 2, and characteristic pressure 3.

[0061] Similarly, in Figure 2 and Figure 3 In this process, regions where multiple voltages, voltage change rates, and temperatures and temperature change rates change significantly can be identified. Using a similar processing method, multiple characteristic voltages and characteristic temperatures can be determined separately.

[0062] In some preferred embodiments, such as Figure 2 As shown, multiple characteristic voltages include characteristic voltage 1, characteristic voltage 2 and characteristic voltage 3, which respectively correspond to the voltage when the voltage reaches its peak value for the first time under overcharge conditions, the voltage when the first derivative of the voltage with respect to time changes from positive to negative for the second time under overcharge conditions, and the voltage when the voltage suddenly increases during the falling phase under overcharge conditions and then decreases again within a certain time (e.g., within 1 second).

[0063] In some preferred embodiments, such as Figure 3 As shown, multiple characteristic temperatures include characteristic temperature 1 and characteristic temperature 2, which correspond to the temperatures when the temperature changes by more than 5°C for the first time under overcharge conditions and the rate of temperature change exceeds 0.1°C / s, and the temperatures when the second derivative of temperature with respect to time changes from a positive value to a negative value.

[0064] The aforementioned characteristic voltages, characteristic temperatures, and characteristic pressures collectively constitute the parametric characteristic values ​​of a battery during overheating runaway. Statistical analysis of the battery's state when it reaches each of these characteristic values ​​and the time elapsed from that state to complete overheating runaway reveals that no single-dimensional parametric characteristic value can fully and accurately reflect the state changes experienced by the battery during overheating runaway. Furthermore, the mapping degree of each parametric characteristic value to the overheating runaway state varies for batteries of different models, specifications, and packaging methods. For example, different battery models may correspond to completely different characteristic voltages when reaching the same characteristic temperature. Similarly, for batteries with soft surfaces and batteries with hard surfaces, their characteristic pressures may undergo completely different changes during the same characteristic voltage and temperature. Therefore, it is necessary to determine the parametric characteristic value with the highest coupling influence weight during overheating runaway for each model to construct a corresponding multi-parameter coupled overheating runaway warning level criterion.

[0065] In some preferred embodiments of this application, such as Figure 5 As shown in the flowchart, the overheat runaway warning level criterion coupled with multiple parameters corresponding to the characteristic battery model is constructed through the following steps:

[0066] S1, Obtain experimental data on overheating runaway of multiple batteries of the same model;

[0067] S2, extract the overheating runaway experimental data of any battery, and perform the following steps in sequence:

[0068] S21, Extract the measured and processed values ​​of each parameter of the battery at each measurement time;

[0069] S22, determine the arrival time of multiple parameter characteristic values ​​of the battery during the overheat runaway process;

[0070] S23, extract the state of charge of the battery at the arrival time of each parameter characteristic value and the difference between the state of charge and the state of charge when the overheating runaway occurs.

[0071] S24, extract the overheat runaway experimental data of another battery of the same model and return to step S21, until all experimental data are traversed;

[0072] S3, Based on the data extracted in step S2, perform correlation mining to obtain the importance of each parameter feature value;

[0073] S4. Based on the importance of each parameter feature value, select a specific parameter feature value to construct a multi-parameter coupled overheat runaway early warning level criterion corresponding to the battery model.

[0074] In the above steps, the overheating runaway test data of multiple batteries of the same model are first obtained through step S1. For each battery, the overheating runaway test data includes voltage, temperature, surface pressure and state of charge data recorded at certain sampling time intervals.

[0075] After obtaining the above raw data, based on the experimental data of each battery, the state of charge when it reaches the characteristic value of each parameter and the difference between the state of charge when it reaches the overheat runaway are statistically analyzed through steps S21 to S23.

[0076] Table 1 below shows the parameter characteristic values ​​obtained from the overheating runaway experiment data of a specific battery model. The meanings of characteristic voltage 1, characteristic voltage 2, characteristic voltage 3, characteristic temperature 1, characteristic temperature 2, characteristic pressure 1, characteristic pressure 2, and characteristic pressure 3 are explained above. The parameter characteristic value column is sorted according to the time it takes to reach each parameter characteristic value.

[0077] Table 1

[0078]

[0079] Table 2 below shows the parameter characteristic values ​​of another battery of this model obtained through the same processing method.

[0080] Table 2

[0081]

[0082] Analysis of the state of charge (SOC) and corresponding parameter measurements of the batteries at various characteristic values ​​in Tables 1 and 2 reveals that different batteries of the same model do not exhibit a simple linear or monotonic relationship between their voltage, temperature, and other parameters when reaching these characteristic values. For example, in Tables 1 and 2, the characteristic voltage of the battery may decrease or initially increase and then decrease as the overheating runaway progresses. This phenomenon illustrates the mutual influence and coupling between battery parameters such as voltage, temperature, and surface pressure. Therefore, when determining the overheating runaway warning level for a specific battery model, the optimal parameter characteristic values ​​should be selected from different characteristic values ​​based on their degree of influence on battery state changes and the strength of the relationships between them to construct the warning level criterion.

[0083] For example, in some preferred embodiments of this application, the Apriori algorithm known to those skilled in the art can be used to perform correlation mining on the discretized parameter feature values ​​to obtain the correlation between them, and the importance of each parameter feature value after correlation mining can be marked to determine the overheat runaway warning level criterion for constructing a multi-parameter coupling corresponding to a specific battery model.

[0084] Figure 6 The diagram illustrates the correlation between the feature values ​​of various parameters obtained using the Apriori algorithm and the importance evaluation indicators in a specific embodiment, where A, B, C, and D are the evaluation indicators sorted by importance. Table 3 below shows the importance evaluation results of the feature values ​​of various overheating runaway parameters obtained according to this embodiment.

[0085] Table 3

[0086] Parameter eigenvalues Importance evaluation results Characteristic temperature 1 unimportant Characteristic voltage 1 Marginal Characteristic voltage 2 Marginal Characteristic pressure 1 important Characteristic voltage 3 important Characteristic pressure 2 important Characteristic temperature 2 unimportant Characteristic pressure 3 important

[0087] The following formula gives the criterion for the overheating runaway early warning level of multi-parameter coupling constructed by selecting specific parameter characteristic values ​​based on the evaluation results of the importance of the above parameter characteristic values ​​in this embodiment:

[0088]

[0089] Among them, U c1 Here, U is the first characteristic voltage, U' is the voltage measured across the battery terminals, and T is the voltage difference. c1 Let T0 be the first characteristic temperature, T be the initial temperature, T be the battery surface temperature, T′ be the temperature difference, and P be the battery surface pressure. -1 This represents the surface pressure of the battery at the previous moment.

[0090] Clearly, for different battery models and specifications, the above steps can be used to obtain the corresponding multi-parameter coupled overheating runaway warning level criteria, so as to achieve early warning of the severity of battery overheating runaway.

[0091] Figure 7 This application illustrates another preferred embodiment, in which, in addition to steps 100 to 300, step 400 is further included: estimating the time difference between the time the battery reaches its current overheat runaway warning level and the time when overheat runaway occurs. Specifically, the time elapsed from reaching a specific overheat runaway level to the occurrence of overheat runaway for a particular battery model can be obtained by statistically analyzing multiple sets of overheat runaway experimental data for that battery model. Specifically, after obtaining the multi-parameter coupled overheat runaway warning level criterion for that battery model using step 300 above, the time when each set of overheat runaway experimental data enters each warning level is marked, and the time elapsed until overheat runaway is calculated. Finally, the time difference between the time the battery model reaches each warning level and the time when overheat runaway occurs is obtained by statistical analysis.

[0092] Table 4 shows the state-of-charge difference, time difference, and comparison with measured data for a specific battery from entering various warning levels to overheating runaway using the method of this embodiment.

[0093] Table 4

[0094]

[0095] As can be seen from Table 4, the difference in state of charge between the four warning levels and the occurrence of thermal runaway, predicted by the method of this application embodiment, is very close to the difference in state of charge between the four warning levels and the occurrence of thermal runaway. The error of the time difference prediction is within 20 seconds, and the warning signal can be issued earlier than the actual overheating runaway. This proves that the method can achieve better multi-parameter coupled thermal runaway early warning.

[0096] Table 5 shows the results of an overheat runaway early warning experiment for a specific battery. Figures 8 to 11 The battery parameter responses after entering each warning level are shown respectively.

[0097] Table 5

[0098]

[0099] Through Table 5 and Figures 8 to 11 It can be seen that Level 1, Level 2, and Level 3 warnings can effectively prevent thermal runaway. At Level 1 warning, the battery shows no damage, but at Level 2 warning, the battery has undergone minor deformation, potentially posing a safety hazard for subsequent use. After a Level 3 warning, the battery is severely damaged, unusable, and requires immediate attention. Level 4 warning fails to prevent thermal runaway, but a certain time elapses between the warning and its occurrence, providing valuable time for rapid evacuation. Level 1 and Level 2 warnings meet the national standard requirement of issuing an alarm signal 5 minutes before a hazard occurs in the passenger compartment, while Level 3 warning, although exceeding this requirement, still prevents thermal runaway. Compared to previous safety redundancy studies that only met national standard safety requirements without considering precise level classification, this study considers both national standard requirements and provides more accurate level classification. The different results corresponding to different warning levels further demonstrate the beneficial effects of graded warnings and proactive countermeasures.

[0100] On the other hand, this application also provides a multi-parameter early warning system for battery overheating runaway through embodiments, such as Figure 12 As shown, the early warning system includes:

[0101] The acquisition unit is used to acquire measured values ​​of various parameters of the battery, including the battery's voltage, temperature, and surface pressure.

[0102] The processing unit is used to process the measured value of each parameter to obtain the processed value of that parameter;

[0103] The judgment unit determines the overheating runaway warning level of the battery based on the measured and processed values ​​through a multi-parameter coupled overheating runaway warning level criterion.

[0104] In some embodiments, the multi-parameter early warning system can be implemented entirely or partially through software, hardware, or a combination thereof. The aforementioned units can be embedded in or independent of the processor in a computer device in hardware form, or stored in the memory of the computer device in software form, so that the processor can call and execute the operations corresponding to each of the above modules. The specific implementation methods of the acquisition unit, processing unit, and judgment unit have been described in detail in the preceding description of the multi-parameter early warning method for battery overheating runaway, and will not be repeated here.

[0105] The specific embodiments of this application have been described in detail above. For those skilled in the art, several improvements and modifications can be made to this application without departing from the principle of this application, and these improvements and modifications also fall within the protection scope of the claims of this application.

Claims

1. A multi-parameter early warning method for battery overheat runaway, characterized in that, The method comprises the following steps: collecting measurement values of multiple parameters of the battery, the parameters including voltage, temperature and surface pressure of the battery; processing the measurement values of the parameters to obtain processed values of the parameters; determining an overheat runaway early warning level of the battery based on the measurement values and the processed values by using an overheat runaway early warning level criterion coupled with multiple parameters; the processed values include: first and second order derivatives of the voltage measurement values with respect to time, first and second order derivatives of the temperature measurement values with respect to time, and a pressure state mutation vector; The pressure state mutation vector is Wherein is the pressure state of the battery surface at the previous measurement time, is the pressure state of the battery surface at the current measurement time, is the cumulative number of times of conversion of the pressure state of the battery surface; when the surface pressure of the battery is less than a preset pressure threshold, the pressure state is a zero state, otherwise the pressure state is a non-zero state; the overheat runaway early warning level criterion is determined by the following steps: S1, obtaining overheat runaway experimental data of multiple batteries of the same type; S2, extracting overheat runaway experimental data of any one battery, and sequentially performing the following steps: S21, extracting measurement values and processed values of each parameter of the battery at each measurement time; S22, determining the arrival time of multiple parameter characteristic values of the battery in the overheat runaway process; S23, extracting the state of charge of the battery at the arrival time of each parameter characteristic value and the difference between the state of charge and the state of charge at the arrival of the overheat runaway; S24, extracting overheat runaway experimental data of another battery of the same type and returning to step S21 until all experimental data are traversed; S3, performing correlation mining based on the data extracted in step S2 to obtain the importance of each parameter characteristic value; S4, selecting a specific parameter characteristic value based on the importance of each parameter characteristic value to construct an overheat runaway early warning level criterion coupled with multiple parameters corresponding to the battery of the same type; the parameter characteristic values include multiple characteristic voltages, multiple characteristic temperatures and multiple characteristic pressures.

2. The multi-parameter early warning method for battery overheat runaway according to claim 1, characterized in that, the multiple characteristic voltages include: the voltage when the voltage reaches a peak value for the first time in the overcharge state, the voltage when the first order derivative of the voltage with respect to time changes from positive to negative for the second time in the overcharge state, and the voltage when the voltage suddenly increases in the falling stage and then decreases again within a certain time in the overcharge state. 3.The multi-parameter pre-warning method for battery overheat runaway according to claim 1, characterized in that, the multiple characteristic temperatures include: the temperature when the temperature changes by more than 5℃ and the temperature change rate is more than 0.1℃ / S for the first time in the overcharge state, and the temperature when the second order derivative of the temperature with respect to time changes from positive to negative.

4. The multi-parameter early warning method of battery overheat runaway according to claim 1, characterized in that, the multiple characteristic pressures include: The vector values are respectively , , pressure state mutation vectors.

5. The multi-parameter pre-warning method of battery overheat runaway according to claim 1, characterized in that, the following steps are further included: estimating the time difference from the time when the battery reaches the overheat runaway early warning level to the time when the overheat runaway occurs.

6. A multi-parameter early warning system for battery overheat runaway, characterized in that, It comprises: a collection unit for collecting measurement values of multiple parameters of the battery, the parameters including voltage, temperature and surface pressure of the battery; a processing unit for processing the measurement values of each parameter to obtain the processed values of the parameter; a judgment unit for determining an overheat runaway early warning level of the battery based on the measurement values and the processed values by using an overheat runaway early warning level criterion coupled with multiple parameters; the processed values include: first and second order derivatives of the voltage measurement values with respect to time, first and second order derivatives of the temperature measurement values with respect to time, and a pressure state mutation vector; The pressure state mutation vector is wherein is the pressure state of the battery surface at the previous measurement time, is the pressure state of the battery surface at the current measurement time, is the cumulative number of times of conversion of the pressure state of the battery surface; When the battery surface pressure is less than a preset pressure threshold, the pressure state is a zero state, otherwise the pressure state is a non-zero state; The overheat runaway early warning level criterion is determined by the following steps: S1, obtaining overheat runaway experimental data of multiple batteries of the same model; S2, extracting overheat runaway experimental data of any one battery, and sequentially performing the following steps: S21, extracting measurement values and processing values of each parameter of the battery at each measurement time; S22, determining the arrival time of multiple parameter characteristic values of the battery during the overheat runaway process; S23, extracting the state of charge of the battery at the arrival time of each parameter characteristic value and the difference between the state of charge and the state of charge at the arrival of the overheat runaway; S24, extracting overheat runaway experimental data of another battery of the same model and returning to step S21 until all experimental data are traversed; S3, based on the data extracted in step S2, correlation mining is performed to obtain the importance of each parameter characteristic value; S4, based on the importance of each parameter characteristic value, a specific parameter characteristic value is selected to construct an overheat runaway early warning level criterion corresponding to the multiple parameter coupling of the battery of the same model; The parameter characteristic values include multiple characteristic voltages, multiple characteristic temperatures and multiple characteristic pressures.

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