Battery thermal boundary current acquisition method, system, equipment, medium and product

Abstract

The invention relates to the technical field of battery thermal management, and discloses a battery thermal boundary current acquisition method, system and device, a medium and a product. The method comprises the following steps: coupling an electrochemical conduction process and a heat conduction process of a target battery to determine an initial electrochemical-thermal coupling model of the target battery; and identifying unknown model parameters of the initial electrochemical-thermal coupling model, and obtaining a thermal abuse current boundary of the target battery by combining a temperature value output by the electrochemical-thermal coupling model obtained by identifying the parameters based on a PID algorithm, so as to accurately capture small current change. The battery thermal boundary current obtaining precision, real-time performance and accuracy are improved, accurate control over the battery thermal boundary current can be achieved through the PID algorithm, and the method is suitable for complex working conditions.

Description

Technical Field

[0001] The present invention relates to the technical field of battery thermal management, and particularly to a method, a system, a device, a medium and a product for obtaining battery thermal boundary current. Background Art

[0002] Due to the characteristics of lithium-ion batteries such as high energy density, high power density, long cycle life and no memory effect, they have been widely used in fields such as electric vehicles and new power systems at present. With the increasing demand for the cruising range of electric vehicles and the scale of grid energy storage, the requirements for the energy and power density of lithium-ion batteries are increasing day by day. The continuously increasing energy and power density cause lithium-ion batteries to generate a large amount of heat during operation, resulting in an increasingly significant temperature rise and temperature difference. Research shows that the performance of the battery is optimal when the battery temperature is between 20°C and 30°C. Therefore, designing an effective thermal management system and formulating a scientific thermal management strategy are of great significance for the high-reliability and long-life operation of the battery system.

[0003] Battery thermal management can start from two aspects: increasing heat dissipation and reducing heat generation. At the design stage of the thermal management system, the heat dissipation conditions of the battery system can be improved by selecting a cooling medium with a large thermal conductivity coefficient and optimizing the flow path of the cooling medium; during the operation stage of the battery system, when the thermal management system reaches its maximum efficiency and still cannot effectively limit the battery temperature rise, it is necessary to further limit the charge and discharge power of the battery, that is, the battery current, to ensure the thermal boundary of the battery system from the perspective of reducing heat generation.

[0004] The method of reducing heat generation is achieved by limiting the battery current. When the cooling system cannot limit the battery temperature within the optimal range, it is necessary to appropriately limit the charge and discharge power of the battery to ensure that the battery operates within the boundary temperature range by reducing heat generation, and improve the thermal boundary of the battery system. Accurately estimating the battery temperature state online through an electrochemical-thermal coupling model, combining with a control algorithm to estimate the thermal boundary current, and controlling the battery heat generation by limiting the battery current are important means to ensure that the battery is at the optimal operating temperature from the source.

[0005] At present, the method for obtaining the battery thermal boundary current is difficult to accurately capture small current changes, resulting in poor accuracy, poor real-time performance, and poor accuracy in obtaining the battery thermal boundary current, and it is difficult to adapt to relatively complex working conditions. Summary of the Invention

[0006] In view of this, the present invention provides a method, a system, a device, a medium and a product for obtaining battery thermal boundary current, which solves the technical problem that the current method for obtaining battery thermal boundary current is difficult to accurately capture small current changes, resulting in poor accuracy, poor real-time performance, and poor accuracy in obtaining the battery thermal boundary current, and it is difficult to adapt to relatively complex working conditions.

[0007] The first aspect of the present invention provides a method for obtaining the thermal boundary current of a battery, including:

[0008] Couple the electrochemical conduction process and the heat conduction process of the target battery to determine the initial electrochemical-thermal coupling model of the target battery; wherein, the initial electrochemical-thermal coupling model is used to describe the temperature change under the influence of the battery terminal current of the target battery.

[0009] Identify the unknown model parameters of the initial electrochemical-thermal coupling model to obtain the electrochemical-thermal coupling model.

[0010] Based on the PID algorithm, obtain the thermal abuse current boundary of the target battery by combining the temperature value output by the electrochemical-thermal coupling model.

[0011] Preferably, the coupling of the electrochemical conduction process and the heat conduction process of the target battery to determine the initial electrochemical-thermal coupling model of the target battery includes:

[0012] According to the electrochemical conduction process of the target battery and the charge and discharge behavior of the battery, determine the electrochemical model of the target battery; wherein, the electrochemical model determines the battery terminal voltage of the target battery according to the open circuit voltage, concentration polarization overpotential, ohmic polarization overpotential and reaction polarization overpotential of the target battery.

[0013] According to the three-dimensional thermal model of the target battery and simplify the heat conduction process of the three-dimensional thermal model to obtain the lumped parameter heat transfer model of the target battery; wherein, the lumped parameter heat transfer model is used to describe the temperature change of the target battery during the heat conduction process.

[0014] Perform parameter coupling according to the electrochemical model and the lumped parameter heat transfer model to obtain the initial electrochemical-thermal coupling model of the target battery.

[0015] Preferably, the method for simplifying the heat conduction process of the three-dimensional thermal model includes at least one of the following methods:

[0016] Regard the heat generation amount at each position inside the target battery as equal.

[0017] Use the surface temperature of the target battery as the average temperature of the target battery to characterize the battery temperature characteristics.

[0018] Regard the heat capacities of different materials inside the target battery as constants.

[0019] Preferably, the unknown model parameters include the unknown model parameters of the electrochemical model and the unknown model parameters of the lumped parameter heat transfer model; the unknown model parameters of the electrochemical model include the open circuit voltage, the concentration polarization overpotential, the ohmic polarization overpotential, and the reaction polarization overpotential; the unknown model parameters of the lumped parameter heat transfer model include the heat dissipation coefficient between the battery and the air and the battery entropy coefficient;

[0020] The identification of the unknown model parameters of the initial electrochemical-thermal coupling model to obtain the electrochemical-thermal coupling model includes:

[0021] Identifying the unknown model parameters of the electrochemical model based on the excitation response analysis method;

[0022] Identifying the heat dissipation coefficient between the battery and the air based on the excitation response analysis method;

[0023] Based on the identification results of the unknown model parameters of the electrochemical model and the identification results of the heat dissipation coefficient between the battery and the air, using a data-driven method and combining the least squares method to identify the battery entropy coefficient;

[0024] Integrating the identification results of the unknown model parameters of the electrochemical model, the identification results of the heat dissipation coefficient between the battery and the air, and the identification results of the battery entropy coefficient to obtain the model parameters of the initial electrochemical-thermal coupling model;

[0025] Updating the initial electrochemical-thermal coupling model according to the model parameters of the initial electrochemical-thermal coupling model to obtain the electrochemical-thermal coupling model.

[0026] Preferably, the method further includes: correcting the identification results of the unknown model parameters of the electrochemical model;

[0027] The correction of the identification results of the unknown model parameters of the electrochemical model includes:

[0028] Based on the Nernst equation, correcting the open circuit voltage according to the open circuit voltage at the reference temperature;

[0029] Based on the Arrhenius equation, correcting the concentration polarization overpotential, the ohmic polarization overpotential, and the reaction polarization overpotential respectively according to the model parameters at the reference temperature.

[0030] Preferably, the obtaining of the thermal abuse current boundary of the target battery based on the PID algorithm and combining the temperature value output by the electrochemical-thermal coupling model includes:

[0031] According to the electrochemical-thermal coupling model, outputting the current temperature value under the condition of inputting the current battery terminal current;

[0032] Subtract the current temperature value from the reference temperature value, input the result of the subtraction into the PID algorithm, output the updated battery terminal current, update the updated battery terminal current as the current battery terminal current, and then go to output the current temperature value under the condition of inputting the current battery terminal current according to the electrochemical-thermal coupling model, and perform iterative loop operations until the discharge voltage of the target battery reaches the preset maximum discharge voltage threshold, at which point the iterative loop stops, and output the current battery terminal current after the iterative loop stops as the thermal abuse current boundary of the target battery.

[0033] In a second aspect, the present invention provides a system for obtaining the thermal boundary current of a battery, comprising:

[0034] A model coupling module, configured to couple the electrochemical conduction process and the heat conduction process of the target battery to determine the initial electrochemical-thermal coupling model of the target battery; wherein, the initial electrochemical-thermal coupling model is used to describe the temperature change under the influence of the battery terminal current of the target battery.

[0035] A parameter identification module, configured to identify the unknown model parameters of the initial electrochemical-thermal coupling model to obtain the electrochemical-thermal coupling model.

[0036] A current boundary obtaining module, configured to obtain the thermal abuse current boundary of the target battery based on the PID algorithm in combination with the temperature value output by the electrochemical-thermal coupling model.

[0037] In a third aspect, the present invention provides an electronic device, which includes a memory and a processor. When the computer program stored in the memory is executed by the processor, the processor is caused to execute the steps of the method for obtaining the thermal boundary current of a battery as described in the first aspect.

[0038] In a fourth aspect, the present invention provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed, the steps of the method for obtaining the thermal boundary current of a battery as described in the first aspect are implemented.

[0039] In a fifth aspect, the present invention provides a computer program product, which includes a computer program stored on a non-transitory computer-readable storage medium. The computer program includes program instructions. When the program instructions are executed by a computer, the computer is caused to execute the steps of the method for obtaining the thermal boundary current of a battery as described in the first aspect.

[0040] As can be seen from the above technical solutions, the present invention couples the electrochemical conduction process and the heat conduction process of the target battery to determine the initial electrochemical-thermal coupling model of the target battery, and identifies the unknown model parameters of the initial electrochemical-thermal coupling model. Based on the PID algorithm, the thermal abuse current boundary of the target battery is obtained by combining the temperature value output by the electrochemical-thermal coupling model obtained from the identified parameters, so as to accurately capture small current changes, improve the accuracy, real-time performance and accuracy of obtaining the battery thermal boundary current, and the precise control of the battery thermal boundary current can be achieved through the PID algorithm, which is suitable for relatively complex working conditions. Description of the Drawings

[0041] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention, and those of ordinary skill in the art can obtain other drawings according to these drawings without creative efforts.

[0042] Figure 1 It is an application environment diagram of a method for obtaining the battery thermal boundary current provided by an embodiment of the present invention;

[0043] Figure 2 It is a flowchart of a method for obtaining the battery thermal boundary current provided by an embodiment of the present invention;

[0044] Figure 3 It is a schematic diagram of the battery equivalent model provided by an embodiment of the present invention;

[0045] Figure 4 It is a schematic diagram of the voltage change when the current changes suddenly provided by an embodiment of the present invention;

[0046] Figure 5 It is a schematic diagram of the control process of the PID algorithm provided by an embodiment of the present invention;

[0047] Figure 6a It is a schematic diagram of the current excitation change provided by an embodiment of the present invention;

[0048] Figure 6b It is a schematic diagram of the voltage response change provided by an embodiment of the present invention;

[0049] Figure 7a It is a schematic diagram of the voltage comparison curve provided by an embodiment of the present invention;

[0050] Figure 7b It is a schematic diagram of the temperature comparison curve provided by an embodiment of the present invention;

[0051] Figure 8a It is a schematic diagram of the current curve provided by an embodiment of the present invention;

[0052] Figure 8b Schematic diagram of the temperature curve provided by an embodiment of the present invention;

[0053] Figure 9 Schematic structural diagram of a battery thermal boundary current acquisition system provided by an embodiment of the present invention;

[0054] Figure 10 Schematic structural diagram of an electronic device provided by an embodiment of the present invention. Detailed implementation manners

[0055] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0056] The battery thermal boundary current acquisition method provided by the embodiments of the present application can be applied to an application environment as Figure 1 shown. Among them, the terminal 101 communicates with the server 102 through a network. The data storage system can store the data that the server 102 needs to process. The data storage system can be integrated on the server 102, or placed in the cloud or other network servers. The terminal 101 or the server 102 couples the electrochemical conduction process and the heat conduction process of the target battery to determine the initial electrochemical-thermal coupling model of the target battery; wherein, the initial electrochemical-thermal coupling model is used to describe the temperature change under the influence of the battery terminal current of the target battery; identify the unknown model parameters of the initial electrochemical-thermal coupling model to obtain the electrochemical-thermal coupling model; based on the PID algorithm, combine the temperature value output by the electrochemical-thermal coupling model to obtain the thermal abuse current boundary of the target battery.

[0057] The terminal 101 can be, but is not limited to, various personal computers, laptop computers, smart phones, tablet computers, etc.

[0058] The server 102 can be an independent physical server, or a server cluster or distributed system composed of multiple physical servers, or a cloud server providing cloud computing services.

[0059] As Figure 2 shown, the embodiments of the present application provide a battery thermal boundary current acquisition method. Taking this method applied to Figure 1 the terminal 101 or the server 102 in it as an example for illustration, the method includes the following steps S1 to S3. Among them:

[0060] Step S1: Couple the electrochemical conduction process and the heat conduction process of the target battery to determine the initial electrochemical-thermal coupling model of the target battery. Among them, the initial electrochemical-thermal coupling model is used to describe the temperature change under the influence of the battery terminal current of the target battery.

[0061] Among them, the electrochemical conduction process is the process in which ions inside the battery migrate under the action of an electric field and generate current, and this process is accompanied by energy conversion and chemical reactions. The heat conduction process is the process in which heat inside the battery is transferred inside the battery and between the battery and the external environment through heat conduction, convection, radiation, etc. Combining the basic working principle of the battery, adding a description of the thermal behavior, establishing the correlation between the internal process of the battery and the external characteristics, and completing the construction of the simplified electrochemical-thermal coupling model, so as to more accurately describe the temperature change of the battery under the influence of the battery terminal current.

[0062] Step S2: Identify the unknown model parameters of the initial electrochemical-thermal coupling model to obtain the electrochemical-thermal coupling model.

[0063] Among them, the unknown model parameters are the key factors affecting the accuracy of the electrochemical-thermal coupling model. By accurately identifying these unknown model parameters, the accuracy and reliability of the electrochemical-thermal coupling model can be further improved. In specific implementation, various parameter identification methods can be used, such as excitation response analysis method, data-driven method, etc., and combined with experimental data or actual operation data, the unknown model parameters are iteratively optimized until an electrochemical-thermal coupling model that meets the accuracy requirements is obtained.

[0064] Step S3: Based on the PID algorithm, obtain the thermal abuse current boundary of the target battery by combining the temperature value output by the electrochemical-thermal coupling model.

[0065] Among them, the Proportional-Integral-Derivative (PID) controller algorithm is used to accurately control the thermal abuse current boundary of the target battery according to the temperature value output by the electrochemical-thermal coupling model. By continuously adjusting the battery terminal current, the battery temperature is kept within a safe range, thus avoiding the occurrence of battery overheating or thermal abuse phenomena.

[0066] During specific implementation, the temperature value output by the electrochemistry-thermal coupling model can be compared with a preset temperature threshold. According to the comparison result and the control law of the PID algorithm, the battery terminal current value that needs to be adjusted is calculated and used as a new input value to be re-input into the electrochemistry-thermal coupling model for iterative calculation until the preset control accuracy is achieved or other stop conditions are met. In this way, the accurate acquisition and effective control of the battery thermal abuse current boundary can be realized, improving the safety and reliability of the battery system.

[0067] It should be noted that in the embodiment of the present application, by coupling the electrochemical conduction process and the heat conduction process of the target battery, the initial electrochemistry-thermal coupling model of the target battery is determined, and the unknown model parameters of the initial electrochemistry-thermal coupling model are identified. Based on the PID algorithm, the temperature value output by the electrochemistry-thermal coupling model obtained by combining the identified parameters is used to obtain the thermal abuse current boundary of the target battery, so as to accurately capture small current changes, improve the accuracy, real-time performance and accuracy of the battery thermal boundary current acquisition, and the precise control of the battery thermal boundary current can be realized through the PID algorithm, which is suitable for relatively complex working conditions.

[0068] In some embodiments, coupling the electrochemical conduction process and the heat conduction process of the target battery to determine the initial electrochemistry-thermal coupling model of the target battery includes:

[0069] Step S101: Determine the electrochemical model of the target battery according to the electrochemical conduction process of the target battery and the charge and discharge behavior of the battery; wherein, the electrochemical model determines the battery terminal voltage of the target battery according to the open circuit voltage, concentration polarization overpotential, ohmic polarization overpotential and reaction polarization overpotential of the target battery.

[0070] Among them, the lithium-ion battery electrochemical model describes the charge and discharge behavior of the battery from the perspective of electrochemical mechanism. The battery terminal voltage U app is the result of the combined action of the internal electrode thermodynamic process, the diffusion process of lithium ions in the solid and liquid phases, the ohmic process and the electrochemical reaction process in the battery. Therefore, the electrochemical model is:

[0071] (1)

[0072] In the formula, U app (t) is the battery terminal voltage at time t, E ocv (t) is the open circuit voltage at time t; η con (t) is the concentration polarization overpotential at time t; η ohm (t) is the ohmic polarization overpotential at time t; η act (t) is the reaction polarization overpotential at time t.

[0073] Among them, the lithium intercalation concentration fraction of the positive and negative electrode active materials directly affects the open-circuit voltage of the battery through the electrode potential curve, and the open-circuit voltage of the battery is calculated as:

[0074] (2)

[0075] where U p is the open-circuit voltage of the battery positive electrode, provided by the battery manufacturer; U n is the open-circuit voltage of the battery negative electrode, provided by the battery manufacturer; y surf is the lithium intercalation concentration fraction on the surface of the positive electrode active material; x surf is the lithium intercalation concentration fraction on the surface of the negative electrode active material.

[0076] The solid-phase diffusion of lithium ions in the electrode active particles causes changes in the lithium intercalation concentration fractions on the surfaces of the positive and negative electrodes, as shown in Equation (3), and further affects the open-circuit voltage of the battery.

[0077] (3)

[0078] where y avg (t) is the average lithium intercalation concentration fraction of the positive electrode active material; x avg (t) is the average lithium intercalation concentration fraction of the negative electrode active material; Δy(t) is the difference between the lithium intercalation concentration fraction on the surface of the positive electrode active material and the average lithium intercalation concentration fraction; Δx(t) is the difference between the lithium intercalation concentration fraction on the surface of the negative electrode active material and the average lithium intercalation concentration fraction.

[0079] In the simplified electrochemical model, a three-parameter parabola is used to approximately solve the lithium ion concentration distribution during the solid-phase diffusion process, and Δy and Δx can be obtained from Equation (4).

[0080] (4)

[0081] where is the positive electrode solid-phase diffusion time constant; is the negative electrode solid-phase diffusion time constant; Q p is the capacity of the negative electrode of the lithium ion battery; Q n is the capacity of the positive electrode of the lithium ion battery; Δy' is an intermediate variable generated during the calculation process; Δx' is an intermediate variable generated during the calculation process, and I app (t) is the battery terminal current.

[0082] The discretization formulas for Δy' and Δx' are:

[0083] (5)

[0084] The liquid-phase diffusion process results in significant lithium ion concentration differences inside the battery, and thus generates a concentration polarization overpotential. The concentration polarization overpotential η con can be obtained from Equation (6).

[0085] (6)

[0086] Wherein, R is the ideal gas constant; F is the Faraday constant (C / mol); c0 is the initial lithium ion concentration of the electrolyte; Δc(t) is the difference in lithium ion concentration of the electrolyte at the positive and negative electrodes; t + is the charge transfer number. The calculation formula of Δc is:

[0087] (7)

[0088] Wherein, τ e is the liquid-phase diffusion time constant; P con is the liquid-phase diffusion coefficient.

[0089] The ohmic effect inside the battery causes the generation of ohmic polarization overpotential. The ohmic effects of each part of the simplified electrochemical model are lumped, and the ohmic internal resistance is used to characterize the combined effect of the ohmic processes of each part. The ohmic polarization overpotential η ohm is as follows:

[0090] (8)

[0091] Wherein, R ohm is the ohmic internal resistance.

[0092] The polarization effect of the electrochemical reaction will generate reaction polarization overpotential. Under the assumption of uniform distribution of the reaction current density, the simplified electrochemical model simplifies the Bulter-Volmer formula, and the reaction polarization overpotential η act can be calculated by the following formula:

[0093] (9)

[0094] Wherein, m p is an intermediate variable in the calculation process; m n is an intermediate variable in the calculation process; P act is the reaction polarization constant.

[0095] Step S102: According to the three-dimensional thermal model of the target battery, and simplifying the heat conduction process of the three-dimensional thermal model, a lumped parameter heat transfer model of the target battery is obtained; wherein, the lumped parameter heat transfer model is used to describe the temperature change of the target battery during the heat conduction process.

[0096] Among them, the three-dimensional thermal model of the target battery describes the temperature distribution inside the battery based on heat transfer methods such as heat conduction, convection, and radiation inside the battery. However, the three-dimensional thermal model often involves a large amount of computing resources and complex calculation processes, which is not conducive to real-time applications. Therefore, in order to simplify the calculation and improve the application efficiency of the model, the heat conduction process of the three-dimensional thermal model can be simplified to obtain a lumped parameter heat transfer model.

[0097] The lumped parameter heat transfer model regards the battery as a whole, ignores the temperature distribution difference inside the battery, and only considers the temperature change of the whole battery. Through reasonable assumptions and simplifications, the heat transfer equation of the whole battery can be derived, thus obtaining the lumped parameter heat transfer model. This model has the advantages of simple calculation and easy implementation, and can meet the needs of real-time applications. As Figure 3 shown, in the embodiments of the present application, the battery in the lumped parameter heat transfer model is regarded as a particle, and heat is exchanged with the surrounding air through the thermal resistance R d Therefore, the temperature obtained by the model is an approximate value.

[0098] To meet the needs of online applications, a large number of approximations and ignorances are made for the heat transfer process of the battery, that is, the ways to simplify the heat conduction process of the three-dimensional thermal model include at least one of the following ways:

[0099] (1) Regard the heat generation amount at each position inside the target battery as equal.

[0100] Among them, by regarding the heat generation amount at each position inside the target battery as equal, the uneven current distribution inside the battery is ignored, and the battery is regarded as a uniformly heated body.

[0101] (2) Use the surface temperature of the target battery as the average temperature of the target battery to characterize the battery temperature characteristics.

[0102] Among them, by assuming that the temperature value at each position inside the battery volume is equal, the temperature difference between the inside and outside of the battery is ignored, and the surface temperature is used instead of the average temperature to characterize the battery temperature characteristics.

[0103] (3) Regard the heat capacities of different materials inside the target battery as constants.

[0104] Among them, by ignoring the differences in the heat capacities of different materials inside laminated and wound lithium-ion batteries, the heat capacity of the battery is regarded as a constant and does not change with temperature.

[0105] Step S103: Perform parameter coupling according to the electrochemical model and the lumped parameter heat transfer model to obtain the initial electrochemical-thermal coupling model of the target battery.

[0106] It should be noted that by constructing a simplified electrochemistry-thermal coupling model in the embodiments of the present application, the computational complexity is significantly reduced. Traditional electrochemistry-thermal coupling models usually contain a large number of complex partial differential equations, which involve a large amount of calculation and are difficult to apply in real time. However, in the present invention, through the lumped parameter method and approximation processing, the model is simplified into a mathematical form that is easy to apply online, while retaining sufficient accuracy.

[0107] According to the energy conservation equation and the lumped parameter heat transfer model, the heat conduction equation of the target battery is obtained and described as the battery temperature T at time t t Calculate the temperature T at time t' t The calculation formula is:

[0108] (10)

[0109] In the formula, Q g (s) is the battery heating power; Q diss (s) is the battery heat dissipation power (W); m is the battery mass; s is the integration variable; C p is the specific heat capacity of the battery.

[0110] The heating power of the battery is calculated by the Bernardi equation, as shown in formula (11):

[0111] (11)

[0112] In the formula, is the entropy coefficient of the battery. According to Newton's cooling law and the lumped parameter heat transfer model, the heat dissipation power of the battery can be calculated by the following formula:

[0113] (12)

[0114] (13)

[0115] In the formula, T a is the temperature of the air around the battery; R d is the thermal resistance between the battery and the air; S surf is the external heat dissipation area of the battery; h d is the heat dissipation coefficient between the battery and the air.

[0116] It can be understood that the battery terminal voltage U app can be obtained through the electrochemistry model. Furthermore, the battery heating power can be calculated through formula 11. After substituting it into the heat transfer equation (11), it can be coupled with the heat conduction to obtain the initial electrochemistry-thermal coupling model.

[0117] As can be seen from the aforementioned formulas (1) to (13), the unknown model parameters include the unknown model parameters of the electrochemical model and the unknown model parameters of the lumped parameter heat transfer model; the unknown model parameters of the electrochemical model include the open circuit voltage, concentration overpotential, ohmic overpotential, and reaction overpotential; the unknown model parameters of the lumped parameter heat transfer model include the heat dissipation coefficient between the battery and the air and the battery entropy coefficient.

[0118] In some embodiments, the unknown model parameters of the initial electrochemical-thermal coupling model are identified to obtain the electrochemical-thermal coupling model, including:

[0119] Step S201: Identify the unknown model parameters of the electrochemical model based on the excitation-response analysis method.

[0120] Among them, the excitation-response analysis method infers the internal parameters of the system by applying a specific excitation signal to the system and observing the response of the system. The core idea of the excitation-response analysis method is to decouple the mechanism processes of each part of the battery from the terminal voltage through different forms of current excitation, and complete the relevant parameter identification for each mechanism process separately.

[0121] In the embodiments of the present application, a known battery terminal current excitation signal can be applied to the electrochemical model, and the response of the battery terminal voltage is observed. By comparing the difference between the actual response and the model prediction response, the unknown parameters of the electrochemical model are continuously adjusted until the error between the actual response and the model prediction response reaches a preset range, so as to realize the identification of the unknown parameters of the electrochemical model.

[0122] Specifically, the parameters of the simplified electrochemical model are shown in Table 1. To avoid obtaining model parameters through destructive testing of the battery, the method based on excitation-response analysis is used for model parameter identification.

[0123] Table 1

[0124]

[0125] 1) Identification of parameters related to open circuit voltage

[0126] According to formulas (2) and (5), the parameters related to the open circuit voltage of the battery are y0, Q p 、Q n 、y ofs 、 With , according to formula (3), y0, Q p 、Q n And y ofs Affect the average lithium intercalation concentration fraction through the transfer of lithium ions during charge and discharge, With Affect the difference between the surface lithium intercalation concentration fraction and the average lithium intercalation concentration fraction through solid-phase diffusion.

[0127] Design a low-rate discharge condition of 0.02 C to complete the identification of the first four parameters. When the battery is discharged at a low rate, the effects of solid-liquid phase diffusion, concentration polarization, and ohmic polarization on the battery terminal voltage can be ignored. The measured battery terminal voltage can be approximately regarded as the open-circuit voltage, and the average lithium intercalation concentration fraction can be approximately regarded as the surface lithium intercalation concentration fraction. Therefore, we have:

[0128] (14)

[0129] In the formula, SoC(t) is the state of charge of the battery; Cap is the total capacity of the battery.

[0130] According to the physical meaning of the parameters to be identified, set the numerical range of parameter fitting, that is, y0 and y ofs represent percentages, and their values range from 0 to 1, while Q p and Q n represent the capacities of the positive and negative electrodes, which are closely related to the total capacity of the battery. Their value ranges should be between 0.1 times and 10 times the total capacity. Therefore, for formula (14), with the SoC curve as the input and the E ocv curve as the output, the values of y0, Q p , Q n and y ofs can be obtained by using the non-linear least squares fitting algorithm.

[0131] Since the solid-phase diffusion time constant of the battery is much larger than the liquid-phase diffusion time constant, design a constant current charge-discharge condition for a long time (greater than 103 seconds) to identify the time constant of the battery solid-phase diffusion process. After a long time of charging or discharging, the diffusion processes in various parts of the battery have tended to be stable. At this time, the calculation formula for the open-circuit voltage of the battery is as follows:

[0132] (15)

[0133] In the formula, is the difference between the surface of the positive electrode active material and the average lithium intercalation concentration fraction under steady state; is the difference between the surface of the negative electrode active material and the average lithium intercalation concentration fraction under steady state.

[0134] Similarly, the values of Δy stable , Δx stable are obtained by using the non-linear least squares fitting algorithm. According to formula (15), the solid-phase diffusion time constants of the positive and negative electrodes and are directly calculated from Δystable and Δxstable.

[0135] Among them, the model parameters related to the reaction polarization process and the ohmic polarization process are P ac t and R ohm . When an instantaneous pulse current is applied to the battery, the change in the battery terminal voltage includes two parts: a rapid change and a slow change, as Figure 4 shown.

[0136] The reaction polarization overpotential and the ohmic polarization overpotential change rapidly with the sudden change of the current. The sum of these two overpotentials, the reaction polarization overpotential and the ohmic polarization overpotential, corresponds to Figure 4 η in fast . The ohmic internal resistance R of the battery ohm can be measured by an AC internal resistance tester, and then the ohmic overpotential η can be calculated using Ohm's law ohm . The calculation formula for the reaction polarization overpotential is as follows

[0137] (16)

[0138] The reaction polarization overpotential is calculated under pulse current excitations of different amplitudes, and the reaction polarization constant P can be identified by using non-linear least squares fitting act . For equation (16), the only unknown parameter is η act , and thus η can be solved through the formula act curve. Then, it can be known from equation (9) that with the current curve as the input and the η act curve as the output, only the reaction polarization constant Pact to be identified is unknown. Therefore, the parameter identification can be directly completed using the least squares method.

[0139] The parameters related to the concentration polarization overpotential include P con and τ e . A series of constant current charge-discharge conditions with a short design time (100 seconds) and different amplitudes are designed for the parameter identification related to the concentration polarization overpotential. Based on the above parameter identification, the calculation of the concentration polarization overpotential is shown in formula (17) as follows:

[0140] (17)

[0141] In the formula, E ocv (t) is the open-circuit potential at time t; η ohm (t) is the ohmic overpotential at time t; η act (t) is the reaction polarization overpotential at time t.

[0142] From η con , the concentration difference of liquid-phase lithium ions at the positive and negative electrode current collector boundaries can be obtained in reverse, as shown in formula (18):

[0143] (18)

[0144] In the formula, R is the ideal gas constant; F is the Faraday constant; c0 is the initial lithium ion concentration of the electrolyte; Δc(t) is the difference in lithium ion concentration of the electrolyte at time t; T(t) is the battery temperature at time t; t + is the charge transfer number.

[0145] According to formula (7), the liquid phase diffusion proportionality coefficient P con and the liquid phase diffusion time constant τ e can be obtained from Δc. For formula (18), the only unknown is Δc. The Δc curve calculation can be completed using the formula. It can be known from formula (7) that with the current curve as the input and the Δc curve as the output, only the liquid phase diffusion proportionality coefficient P con and the liquid phase diffusion time constant τ e are unknown. Therefore, the least squares method can be used to directly complete the identification of the two parameters together. Since lithium ion batteries are highly sensitive to temperature, the above parameter identification process except for the small rate operating conditions needs to be completed at a fixed temperature. The temperature correction of the model parameters needs to be completed based on the model parameters identified at different temperatures.

[0146] In order to make the identified parameters more accurate, the embodiment of the present application also corrects the identification results of the unknown model parameters of the electrochemical model;

[0147] Specifically, correcting the identification results of the unknown model parameters of the electrochemical model includes:

[0148] Step S21: Based on the Nernst equation, correct the open circuit voltage according to the open circuit voltage at the reference temperature.

[0149] Among them, since temperature affects the open circuit voltage, ohmic polarization overpotential, reaction polarization overpotential, and concentration polarization overpotential of the battery. First, the effect of temperature on the open circuit voltage of the battery follows the Nernst equation, as shown in formula (19)

[0150] (19)

[0151] In the formula, is the open circuit voltage (V) at the reference temperature; T(t) represents the battery temperature at time t, T ref is the battery reference temperature; is the entropy heat coefficient.

[0152] Step S22: Based on the Arrhenius equation, correct the concentration polarization overpotential, ohmic polarization overpotential, and reaction polarization overpotential respectively according to the model parameters at the reference temperature.

[0153] Among them, since the influence of temperature on the relevant parameters of the battery ohmic polarization process, reaction polarization process, and concentration polarization process follows the Arrhenius equation, as shown in formula (20):

[0154] (20)

[0155] In the formula: is the model parameter to be corrected; is the model parameter value at the reference temperature, ∈ concentration polarization overpotential, ohmic polarization overpotential, and reaction polarization overpotential; is the activation energy.

[0156] It should be noted that the embodiment of the present application considers the influence of temperature on the battery model parameters, and corrects the model parameters for temperature through the Arrhenius formula and the Nernst equation, improving the applicability of the model under different temperature conditions.

[0157] Step S202: Identify the heat dissipation coefficient between the battery and the air based on the excitation response analysis method.

[0158] Among them, according to the heat generation equation, when the external current is zero, the total heat generation rate of the battery is zero, and the change rate of the battery temperature can be considered approximately equal. The approximate calculation formula for the battery temperature is obtained as:

[0159] (21)

[0160] The above formula satisfies that when t = 0, T t is the initial battery temperature T0; when k = ∞, Tt is the ambient temperature T a . Rearranging the above formula gives:

[0161] (22)

[0162] (23)

[0163] Among them, the parameter to be identified in formula (23) is the heat dissipation coefficient h between the battery and the air d .

[0164] Since the above derivation process is carried out under the condition that the external current is zero, the embodiment of the present application places the battery after the battery terminal voltage reaches the discharge cut-off point, and uses the battery temperature data during the placement period to fit the time constant τ heat , that is, during placement, the current is zero, and at this time the battery does not generate heat. Its temperature calculation formula is (22), where T0 and T a are the initial battery temperature and the ambient temperature respectively, and both can be measured using a temperature sensor. t can be regarded as the placement time curve, and Tt It can be regarded as the battery temperature curve when shelved. Therefore, the only unknown parameter in (22) is τ heat , which can be obtained using the least squares method. Then, since the only unknown parameter in Equation (23) is the heat dissipation coefficient h between the battery and the air d , and other parameters are the physical properties parameters of the battery, which can be obtained through measurement and consulting the battery manufacturer. Thus, the heat dissipation coefficient h between the battery and the air can be identified d .

[0165] Step S203: Based on the identification results of the unknown model parameters of the electrochemical model and the identification results of the heat dissipation coefficient between the battery and the air, a data-driven method is adopted, and the least squares method is combined to identify the battery entropy coefficient

[0166] After the above parameter identification is completed, the only unknown parameter of the electrochemistry-thermal coupling model is the battery entropy coefficient. Therefore, based on the identification results of the above electrochemical model parameters and h d , a data-driven method is adopted. With a constant current discharge of 1C as the identification condition, the input is the current at this time, and the output is the battery temperature, both of which can be measured by sensors. Based on these data, using the electrochemistry-thermal coupling model and combining the least squares method, the entropy coefficient curve under this condition can be obtained, and a polynomial fitting is performed on it to obtain the battery entropy coefficient

[0167] Step S204: Integrate the identification results of the unknown model parameters of the electrochemical model, the identification results of the heat dissipation coefficient between the battery and the air, and the identification results of the battery entropy coefficient to obtain the model parameters of the initial electrochemistry-thermal coupling model

[0168] Step S205: Update the initial electrochemistry-thermal coupling model according to the model parameters of the initial electrochemistry-thermal coupling model to obtain the electrochemistry-thermal coupling model

[0169] Among them, after obtaining the identification results of the unknown model parameters of the electrochemical model, the identification results of the heat dissipation coefficient between the battery and the air, and the identification results of the battery entropy coefficient, the model parameters of the initial electrochemistry-thermal coupling model can be obtained and substituted into the initial electrochemistry-thermal coupling model to obtain the electrochemistry-thermal coupling model

[0170] It can be understood that the embodiment of the present application uses the excitation response analysis method for model parameter identification, avoiding the need for destructive testing of the battery in the traditional method. By designing different current excitation conditions, each mechanism process of the battery (such as open circuit voltage, concentration polarization, ohmic polarization, and reaction polarization) is gradually decoupled, realizing accurate parameter identification

[0171] In some embodiments, based on the PID algorithm, the thermal abuse current boundary of the target battery is obtained by combining the temperature value output by the electrochemical-thermal coupling model, including:

[0172] Step S301: According to the electrochemical-thermal coupling model, under the condition of inputting the current battery terminal current, output the current temperature value;

[0173] Step S302: Subtract the current temperature value from the reference temperature value, input the difference result into the PID algorithm, output the updated battery terminal current, update the updated battery terminal current as the current battery terminal current, and then go to output the current temperature value according to the electrochemical-thermal coupling model under the condition of inputting the current battery terminal current, and perform iterative loop operations until the discharge voltage of the target battery reaches the preset maximum discharge voltage threshold, at which point the iterative loop stops, and output the current battery terminal current after the iterative loop stops as the thermal abuse current boundary of the target battery.

[0174] Among them, the PID algorithm is a commonly used control method, which is applied in estimating the thermal boundary current in the present invention. The design of the PID algorithm includes three parts: Proportional, Integral, and Differential. The PID control algorithm combines three links of proportional, integral, and differential. The essence of its control is to perform operations according to the function relationships of proportional, integral, and differential based on the input deviation value, and the operation result is used to control the output.

[0175] The design of the PID controller involves the adjustment of three key parameters of proportional, integral, and differential to ensure the accurate estimation of the electrical abuse boundary. The PID output structure formula is as shown in Equation (24):

[0176] (24)

[0177] In the formula, K P is the proportionality constant; K I is the integral constant; K D is the differential constant; e(t) is the control variable (the difference between the temperature set value and the temperature estimated by the electrochemical-thermal coupling model); U(t) is the output value. When the PID controller controls a predetermined target, the parameter settings are usually set according to the characteristics of the predetermined target.

[0178] The basic structure of the PID control algorithm is as Figure 5 shown. The temperature set value refers to the maximum temperature allowed for the battery, that is, when the temperature of a single battery exceeds this set value, it is considered that the battery will be in danger. The battery model refers to the previous electrochemical-thermal coupling model, which can output the battery terminal voltage and temperature at this time when the battery terminal current is input.

[0179] Combined with a simplified electrochemistry-thermal coupling battery model, the required parameters, namely the state of charge (SOC) at the previous cycle, temperature, current, etc., are transmitted to the PID controller. Based on the PID algorithm, current estimation is realized and then fed back to the battery model in this cycle. By utilizing the parameters such as SOC, temperature, and current included in the model at the previous cycle, the maximum current at which the battery discharge does not cause the temperature to exceed the limit value is obtained through the PID algorithm and transmitted to the electrochemical model. Thereby, the SOC, voltage, and temperature of the battery at this current are obtained, and the parameters such as SOC, temperature, and current are transmitted to the PID algorithm again to obtain the thermal boundary current of the next cycle until the iteration stops when the entire working condition is completed (for example: the battery discharge voltage reaches the limit value). Thus, the thermal abuse boundary current under the full SOC can be obtained, that is, when the battery operates at this current, the battery temperature will not exceed the limit value, and it includes the current boundary data of any SOC under the entire working condition.

[0180] It should be noted that in the embodiment of the present application, the PID control algorithm is introduced into the thermal boundary current estimation. Through the adjustment of the proportional, integral, and differential links, the precise control of the battery thermal boundary current is realized. The introduction of the PID algorithm makes the current estimation have a higher dynamic response ability. By combining the simplified electrochemistry-thermal coupling model and the PID control algorithm, the thermal boundary current estimation within the full state of charge SOC range is realized. This method can dynamically adjust the current boundary to ensure the thermal safety of the battery under different SOC states.

[0181] To specifically illustrate the method we used, the thermal boundary current estimation process of a lithium iron phosphate battery is taken as an implementation case in the present invention. In this implementation, the acquisition of the battery terminal voltage and current is realized through a Neware high-performance battery charge and discharge tester and an auxiliary temperature measurement channel. During the test process, the current and voltage data correspond one by one in time sequence. The parameter identification working conditions in this implementation are as Figures 6a - 6b shown, and it is considered that the discharge current is positive in the current excitation.

[0182] In this embodiment, with an ambient temperature of 20°C, the battery is discharged at a constant current of 1C as the test working condition to investigate the accuracy of the model in simulating the internal and external characteristics of the battery. The comparison curves of the measured values and simulation values of the lithium-ion battery terminal voltage and temperature are as Figures 7a - 7b shown.

[0183] For the identified working conditions of the simplified electrochemistry-thermal coupling model in this embodiment, the average absolute errors of the terminal voltage and temperature simulation do not exceed 12.5 mV and 0.18 K respectively, and the accurate simulation of the internal and external characteristics of the battery can be realized.

[0184] Based on the established PID controller and combined with the battery model, this embodiment realizes the estimation of the thermal boundary current of lithium-ion batteries. In this embodiment, the maximum temperature boundary target value is set to 303.15K. Figures 8a - 8b The estimation results of the thermal boundary current and the temperature change curve within the full SOC range of the lithium-ion battery during the 2.5C constant current discharge process are given.

[0185] It can be seen from Figures 8a - 8b that when the battery discharges at a constant current of 2.5C, the temperature will increase sharply and exceed the set threshold at about 600s. At this time, if the discharge current is changed and the discharge is carried out with the thermal boundary described in the embodiment of the present application, the battery temperature will be effectively improved and the battery safety will be protected. From the newly added temperature curve that always fits the set temperature threshold, it can be proved that the estimation of the thermal boundary current in the embodiment of the present application is accurate.

[0186] Based on the same inventive concept, the embodiment of the present application also provides a battery thermal boundary current acquisition system for implementing the battery thermal boundary current acquisition method involved above.

[0187] The implementation solution provided by this system to solve the problem is similar to the implementation solution recorded in the above method. Therefore, the specific limitations in one or more embodiments of the battery thermal boundary current acquisition system provided below can refer to the limitations on the battery thermal boundary current acquisition method in the above text, and will not be elaborated here.

[0188] As Figure 9 shown, the embodiment of the present application provides a battery thermal boundary current acquisition system, including:

[0189] A model coupling module 100, configured to couple the electrochemical conduction process and the heat conduction process of the target battery to determine the initial electrochemical-thermal coupling model of the target battery; wherein, the initial electrochemical-thermal coupling model is used to describe the temperature change under the influence of the battery terminal current of the target battery.

[0190] A parameter identification module 200, configured to identify the unknown model parameters of the initial electrochemical-thermal coupling model to obtain the electrochemical-thermal coupling model.

[0191] A current boundary acquisition module 300, configured to obtain the thermal abuse current boundary of the target battery based on the PID algorithm and in combination with the temperature value output by the electrochemical-thermal coupling model.

[0192] In some embodiments, the model coupling module 100 is configured to:

[0193] Determine the electrochemical model of the target battery according to the electrochemical conduction process of the target battery and the charge-discharge behavior of the battery; wherein, the electrochemical model determines the battery terminal voltage of the target battery based on the open-circuit voltage, concentration polarization overpotential, ohmic polarization overpotential, and reaction polarization overpotential of the target battery.

[0194] According to the three-dimensional thermal model of the target battery and by simplifying the heat conduction process of the three-dimensional thermal model, obtain the lumped parameter heat transfer model of the target battery; wherein, the lumped parameter heat transfer model is used to describe the temperature change of the target battery during the heat conduction process.

[0195] Perform parameter coupling according to the electrochemical model and the lumped parameter heat transfer model to obtain the initial electrochemistry-thermal coupling model of the target battery.

[0196] In some embodiments, the method of simplifying the heat conduction process of the three-dimensional thermal model includes at least one of the following methods:

[0197] Regard the heat generation amount at each position inside the target battery as an equal heat generation amount.

[0198] Take the surface temperature of the target battery as the average temperature of the target battery to characterize the battery temperature characteristics.

[0199] Regard the heat capacities of different materials inside the target battery as constants.

[0200] In some embodiments, the unknown model parameters include the unknown model parameters of the electrochemical model and the unknown model parameters of the lumped parameter heat transfer model; the unknown model parameters of the electrochemical model include the open-circuit voltage, concentration polarization overpotential, ohmic polarization overpotential, and reaction polarization overpotential; the unknown model parameters of the lumped parameter heat transfer model include the heat dissipation coefficient between the battery and the air and the battery entropy coefficient.

[0201] The parameter identification module 200 is used for:

[0202] Identify the unknown model parameters of the electrochemical model based on the excitation-response analysis method.

[0203] Identify the heat dissipation coefficient between the battery and the air based on the excitation-response analysis method.

[0204] Based on the identification results of the unknown model parameters of the electrochemical model and the identification result of the heat dissipation coefficient between the battery and the air, adopt a data-driven method and combine the least squares method to identify the battery entropy coefficient.

[0205] Integrate the identification results of the unknown model parameters of the electrochemical model, the identification result of the heat dissipation coefficient between the battery and the air, and the identification result of the battery entropy coefficient to obtain the model parameters of the initial electrochemistry-thermal coupling model.

[0206] Update the initial electrochemistry-thermal coupling model according to the model parameters of the initial electrochemistry-thermal coupling model to obtain the electrochemistry-thermal coupling model.

[0207] In some embodiments, the system further includes: a correction module for correcting the identification result of the unknown model parameters of the electrochemistry model;

[0208] The correction module is specifically configured to:

[0209] Based on the Nernst equation, correct the open-circuit voltage according to the open-circuit voltage at the reference temperature;

[0210] Based on the Arrhenius equation, correct the concentration polarization overpotential, the ohmic polarization overpotential, and the reaction polarization overpotential respectively according to the model parameters at the reference temperature.

[0211] In some embodiments, the current boundary acquisition module 300 is configured to:

[0212] Output the current temperature value according to the electrochemistry-thermal coupling model under the condition of inputting the current battery terminal current;

[0213] Take the difference between the current temperature value and the reference temperature value, input the difference result into the PID algorithm, output the updated battery terminal current, update the updated battery terminal current as the current battery terminal current, and then go to output the current temperature value according to the electrochemistry-thermal coupling model under the condition of inputting the current battery terminal current, and perform iterative loop operations until the discharge voltage of the target battery reaches the preset maximum discharge voltage threshold, at which point the iterative loop stops, and output the current battery terminal current after the iterative loop stops as the thermal abuse current boundary of the target battery.

[0214] As Figure 10 shown, an embodiment of the present application provides an electronic device. The electronic device 10 includes a memory 20 and a processor 30. A computer program is stored in the memory 20. When the computer program is executed by the processor 30, the processor 30 is caused to execute the steps of the battery thermal boundary current acquisition method in the above embodiment.

[0215] An embodiment of the present application provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed, the steps of the battery thermal boundary current acquisition method in the above embodiment are implemented.

[0216] An embodiment of the present application provides a computer program product. The computer program product includes a computer program stored on a non-transitory computer-readable storage medium. The computer program includes program instructions. When the program instructions are executed by a computer, the computer is caused to execute the steps of the battery thermal boundary current acquisition method described in the above embodiment.

[0217] Those skilled in the art can clearly understand that for the convenience and brevity of description, the specific working processes of the systems, electronic devices, computer storage media, and computer program products described above can refer to the corresponding processes in the foregoing method embodiments and will not be elaborated herein.

[0218] It should be noted that the terms "including" and "having" and any variations thereof in the specification and claims of the present invention and the above-mentioned drawings are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products, or devices.

[0219] It should be understood that although the steps in the flowcharts involved in the above-described embodiments are shown in sequence according to the indications of the arrows, these steps do not necessarily have to be executed in the order indicated by the arrows. Unless otherwise clearly stated in this article, there is no strict order restriction for the execution of these steps, and these steps can be executed in other orders. Moreover, at least a part of the steps in the flowcharts involved in the above-described embodiments may include multiple steps or multiple stages. These steps or stages do not necessarily have to be executed at the same time, but can be executed at different times. The execution order of these steps or stages does not necessarily have to be sequential, but can be executed alternately or in turn with at least a part of other steps or steps or stages in other steps.

[0220] In several embodiments provided by the present invention, it should be understood that the disclosed systems, electronic devices, computer storage media, computer program products, and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For example, the division of the units is only a logical function division, and there may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed couplings or direct couplings or communication connections to each other can be through some interfaces, and the indirect couplings or communication connections of devices or units can be in electrical, mechanical, or other forms.

[0221] The units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they can be located in one place or distributed to multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0222] In addition, in each embodiment of the present invention, each functional unit may be integrated into a processing unit, or each unit may exist physically alone, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of a software functional unit.

[0223] If the above-mentioned integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on such an understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of this technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for a computer device (which may be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in each embodiment of the present invention. The aforementioned storage medium includes: various media such as USB flash drives, mobile hard disks, read-only memories (English full name: Read-Only Memory, English abbreviation: ROM), random access memories (English full name: Random Access Memory, English abbreviation: RAM), magnetic disks, or optical discs that can store program codes.

[0224] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of each embodiment of the present invention.

Claims

1. A method for obtaining the battery thermal boundary current, characterized in that Including: Couple the electrochemical conduction process and the heat conduction process of the target battery to determine the initial electrochemical-thermal coupling model of the target battery; wherein, the initial electrochemical-thermal coupling model is used to describe the temperature change under the influence of the battery terminal current of the target battery; Identify the unknown model parameters of the initial electrochemical-thermal coupling model to obtain the electrochemical-thermal coupling model; Based on the PID algorithm, obtain the thermal abuse current boundary of the target battery by combining the temperature value output by the electrochemical-thermal coupling model.

2. The method for obtaining the battery thermal boundary current according to claim 1, wherein The coupling of the electrochemical conduction process and the heat conduction process of the target battery to determine the initial electrochemical-thermal coupling model of the target battery includes: Determine the electrochemical model of the target battery according to the electrochemical conduction process of the target battery and the charge and discharge behavior of the battery; wherein, the electrochemical model determines the battery terminal voltage of the target battery according to the open circuit voltage, concentration polarization overpotential, ohmic polarization overpotential and reaction polarization overpotential of the target battery; According to the three-dimensional thermal model of the target battery and simplify the heat conduction process of the three-dimensional thermal model to obtain the lumped parameter heat transfer model of the target battery; wherein, the lumped parameter heat transfer model is used to describe the temperature change of the target battery in the heat conduction process; Perform parameter coupling according to the electrochemical model and the lumped parameter heat transfer model to obtain the initial electrochemical-thermal coupling model of the target battery.

3. The method for obtaining the battery thermal boundary current according to claim 2, wherein The method of simplifying the heat conduction process of the three-dimensional thermal model includes at least one of the following methods: Regard the heat generation amount at each position in the target battery as equal heat generation amount; Use the surface temperature of the target battery as the average temperature of the target battery to characterize the battery temperature characteristics; Regard the heat capacity of different materials inside the target battery as a constant.

4. The method for obtaining the battery thermal boundary current according to claim 2, wherein The unknown model parameters include the unknown model parameters of the electrochemical model and the unknown model parameters of the lumped parameter heat transfer model; the unknown model parameters of the electrochemical model include open circuit voltage, concentration polarization overpotential, ohmic polarization overpotential and reaction polarization overpotential; the unknown model parameters of the lumped parameter heat transfer model include the heat dissipation coefficient between the battery and the air and the battery entropy coefficient; The identification of the unknown model parameters of the initial electrochemical-thermal coupling model to obtain the electrochemical-thermal coupling model includes: Identify the unknown model parameters of the electrochemical model based on the excitation response analysis method; Identify the heat dissipation coefficient between the battery and the air based on the excitation response analysis method; Based on the identification results of the unknown model parameters of the electrochemical model and the identification result of the heat dissipation coefficient between the battery and the air, use a data-driven method and combine the least squares method to identify the battery entropy coefficient; Integrate the identification results of the unknown model parameters of the electrochemical model, the identification result of the heat dissipation coefficient between the battery and the air, and the identification result of the battery entropy coefficient to obtain the model parameters of the initial electrochemical-thermal coupling model; Updating the initial electrochemistry-thermal coupling model according to the model parameters of the initial electrochemistry-thermal coupling model to obtain the electrochemistry-thermal coupling model.

5. The method for obtaining the battery thermal boundary current according to claim 4, wherein It further includes: Correcting the identification result of the unknown model parameters of the electrochemistry model; The correction of the identification result of the unknown model parameters of the electrochemistry model includes: Based on the Nernst equation, correcting the open-circuit voltage according to the open-circuit voltage at the reference temperature; Based on the Arrhenius equation, correcting the concentration polarization overpotential, the ohmic polarization overpotential, and the reaction polarization overpotential respectively according to the model parameters at the reference temperature.

6. The method for obtaining the battery thermal boundary current according to any one of claims 1 to 5, characterized in that The obtaining of the thermal abuse current boundary of the target battery based on the PID algorithm in combination with the temperature value output by the electrochemistry-thermal coupling model includes: According to the electrochemistry-thermal coupling model, outputting the current temperature value under the condition of inputting the current battery terminal current; Taking the difference between the current temperature value and the reference temperature value, inputting the difference result into the PID algorithm, outputting the updated battery terminal current, updating the updated battery terminal current as the current battery terminal current, and turning to outputting the current temperature value according to the electrochemistry-thermal coupling model under the condition of inputting the current battery terminal current, and performing iterative loop operations until the discharge voltage of the target battery reaches the preset maximum discharge voltage threshold, stopping the iterative loop, and outputting the current battery terminal current after the iterative loop stops as the thermal abuse current boundary of the target battery.

7. A battery thermal boundary current acquisition system, characterized in that, It includes: A model coupling module, configured to couple the electrochemistry conduction process and the heat conduction process of the target battery to determine the initial electrochemistry-thermal coupling model of the target battery; wherein, the initial electrochemistry-thermal coupling model is used to describe the temperature change under the influence of the battery terminal current of the target battery; A parameter identification module, configured to identify the unknown model parameters of the initial electrochemistry-thermal coupling model to obtain the electrochemistry-thermal coupling model; A current boundary obtaining module, configured to obtain the thermal abuse current boundary of the target battery based on the PID algorithm in combination with the temperature value output by the electrochemistry-thermal coupling model.

8. An electronic device, characterized in that, The electronic device includes a memory and a processor. When the computer program stored in the memory is executed by the processor, the processor executes the steps of the battery thermal boundary current obtaining method according to any one of claims 1-6.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed, it realizes the steps of the battery thermal boundary current obtaining method according to any one of claims 1-6.

10. A computer program product, characterized in that, The computer program product includes a computer program stored on a non-transitory computer-readable storage medium. The computer program includes program instructions. When the program instructions are executed by a computer, the computer executes the steps of the battery thermal boundary current obtaining method according to any one of claims 1-6.

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