A detection method, device, equipment and medium for the cooling capacity of a battery pack

Abstract

The present application discloses a method, device, equipment and medium for detecting the cooling capacity of a battery pack. When it is determined that the battery pack meets the establishment condition, a temperature model of the battery pack is established. Using the temperature model, a first correspondence between the temperature of the temperature measurement point of the battery pack and time can be obtained. Then, the heat transfer coefficient is obtained by fitting the first correspondence between temperature and time. The cooling capacity of the battery pack is measured according to the heat transfer coefficient. The established temperature model can better describe the first correspondence between the temperature of the temperature measurement point of the battery pack and time. The heat transfer coefficient obtained by fitting the first correspondence between temperature and time is relatively accurate. According to the heat transfer coefficient, the cooling capacity of the battery pack can be determined, and the battery pack with a malfunction in the cooling system can be discovered in time.

Description

Technical Field

[0001] The present application relates to the field of detection technology, and particularly relates to a method, device, equipment and medium for detecting the cooling capacity of a battery pack. Background Art

[0002] A battery pack is configured in a vehicle. The battery pack is used to store electrical energy and provide electrical energy for the vehicle so that the vehicle can operate normally. The temperature of the battery pack changes with the operating state of the vehicle and reflects the state of the battery pack to a certain extent.

[0003] The temperature of the battery pack is affected by the operating state of the vehicle and the external environment. Since there are many operating states of the vehicle and the external environment is relatively complex, it is difficult to measure the state of the battery pack only based on the temperature of the battery pack. When a fault occurs in the cooling system of the battery pack, heat cannot be dissipated in time, resulting in the battery pack operating under extreme conditions, reducing the battery life and affecting the normal operation of the vehicle. Therefore, how to accurately detect the cooling capacity of the battery pack is a technical problem to be solved. Summary of the Invention

[0004] In view of this, the present application provides a method, device, equipment and medium for detecting the cooling capacity of a battery pack, which can accurately determine the cooling capacity of the battery pack.

[0005] To solve the above problems, the technical solutions provided by the present application are as follows:

[0006] In a first aspect, the present application provides a method for detecting the cooling capacity of a battery pack, the method including:

[0007] In response to determining that the battery pack meets the establishment condition, establish a temperature model of the battery pack, the temperature model being used to describe the correspondence between the temperature of the battery pack and time, and the model parameters of the temperature model including a heat transfer coefficient, the heat transfer coefficient being the heat transfer coefficient from the coolant to the bottom surface of the battery;

[0008] Obtain a first correspondence between the temperature of the temperature measurement point of the battery pack and time by using the temperature model;

[0009] Fit the heat transfer coefficient by using the first correspondence between the temperature and time;

[0010] Determine the cooling capacity of the battery pack according to the heat transfer coefficient.

[0011] In some possible implementation manners, the establishment condition is that the cooling system of the battery pack operates stably.

[0012] In some possible implementation manners, the stable operation of the battery pack means that the operation duration of the cooling system of the battery pack exceeds the stable duration.

[0013] In some possible implementations, the heat transfer coefficient is an unknown quantity to be determined, and obtaining the heat transfer coefficient by fitting using the first correspondence between the temperature and time includes:

[0014] Obtaining a second correspondence between the temperature and time at the temperature measurement point, where the second correspondence is determined by measurement;

[0015] Fitting the heat transfer coefficient using the second correspondence between the temperature and time and the first correspondence between the temperature and time to obtain a fitting result;

[0016] Determining the heat transfer coefficient according to a fitting evaluation index and the fitting result, where the fitting evaluation index is used to measure the gap between the first correspondence between the temperature and time and the second correspondence between the temperature and time.

[0017] In some possible implementations, the fitting evaluation index is the mean square error.

[0018] In some possible implementations, determining the cooling capacity of the battery pack according to the heat transfer coefficient includes:

[0019] When the heat transfer coefficient is lower than a first threshold, it is determined that the cooling capacity of the battery pack fails.

[0020] In a second aspect, the present application provides a detection device for the cooling capacity of a battery pack, where the device includes:

[0021] A building unit, configured to build a temperature model of the battery pack in response to determining that the battery pack meets the building condition, where the temperature model is used to describe the correspondence between the temperature and time of the battery pack, and the model parameters of the temperature model include a heat transfer coefficient, and the heat transfer coefficient is the heat transfer coefficient from the coolant to the bottom surface of the battery;

[0022] A calculation unit, configured to obtain a first correspondence between the temperature and time at the temperature measurement point of the battery pack using the temperature model;

[0023] A fitting unit, configured to obtain the heat transfer coefficient by fitting using the first correspondence between the temperature and time;

[0024] A determining unit, configured to determine the cooling capacity of the battery pack according to the heat transfer coefficient.

[0025] In a possible implementation, the building condition is that the cooling system of the battery pack operates stably.

[0026] In a possible implementation, the battery pack operates stably when the operating duration of the cooling system of the battery pack exceeds a stable duration.

[0027] In a possible implementation, the heat transfer coefficient is an unknown quantity to be determined. The fitting unit is configured to obtain a second correspondence between the temperature of the temperature measurement point and time, where the second correspondence is determined by measurement; fit the heat transfer coefficient using the second correspondence between the temperature and time and the first correspondence between the temperature and time to obtain a fitting result; determine the heat transfer coefficient according to a fitting evaluation index and the fitting result, where the fitting evaluation index is used to measure the gap between the first correspondence between the temperature and time and the second correspondence between the temperature and time.

[0028] In a possible implementation, the fitting evaluation index is the mean square error.

[0029] In a possible implementation, the determination unit is configured to determine that a failure occurs in the cooling capacity of the battery pack when the heat transfer coefficient is lower than a first threshold.

[0030] In a third aspect, the present application provides a detection device for the cooling capacity of a battery pack, including: a processor, a memory, and a system bus;

[0031] The processor and the memory are connected through the system bus;

[0032] The memory is configured to store one or more programs, and the one or more programs include instructions that, when executed by the processor, cause the processor to execute the method described in the first aspect.

[0033] In a fourth aspect, the present application provides a computer-readable storage medium storing instructions that, when run on a terminal device, cause the terminal device to execute the method described in the first aspect.

[0034] It can be seen that the present application has the following beneficial effects:

[0035] A detection method, device, equipment, and medium for the cooling capacity of a battery pack provided by the present application, when it is determined that the battery pack meets the establishment condition, establish a temperature model of the battery pack. Using the temperature model, a first correspondence between the temperature of the temperature measurement point of the battery pack and time can be obtained. Then, the heat transfer coefficient is obtained by fitting using the first correspondence between the temperature and time. The cooling capacity of the battery pack is measured according to the heat transfer coefficient. The established temperature model can better describe the first correspondence between the temperature of the temperature measurement point of the battery pack and time. The heat transfer coefficient obtained by fitting using the first correspondence between the temperature and time is relatively accurate. According to the heat transfer coefficient, the cooling capacity of the battery pack can be determined, and the battery pack with a malfunction in the cooling system can be discovered in time. Description of the Drawings

[0036] To more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0037] Figure 1 Schematic flowchart of a method for detecting the cooling capacity of a battery pack provided by an embodiment of the present application;

[0038] Figure 2 Schematic diagram of the temperature field of a battery pack provided by an embodiment of the present application;

[0039] Figure 3 Schematic diagram of the distribution of a fitting result provided by an embodiment of the present application;

[0040] Figure 4 Schematic structural diagram of a device for detecting the cooling capacity of a battery pack provided by an embodiment of the present application. Detailed implementation manners

[0041] To facilitate the understanding and interpretation of the technical solutions provided by the embodiments of the present application, the background technology of the present application will be described first.

[0042] During the operation of the vehicle's battery pack, certain heat will be generated. The cooling system of the battery pack can conduct the excess heat, enabling the battery pack to operate within the normal temperature range. The temperature of the battery pack can reflect the operation of the cooling system to a certain extent. However, the temperature of the battery pack is affected by various factors, and it is difficult to accurately judge the cooling capacity of the battery pack only based on the temperature of the battery pack.

[0043] Based on this, the present application provides a method, device, equipment and medium for detecting the cooling capacity of a battery pack. When it is determined that the battery pack meets the establishment condition, a temperature model of the battery pack is established. Using the temperature model, the first correspondence between the temperature of the temperature measurement points of the battery pack and time can be obtained. Then, the heat transfer coefficient is obtained by fitting the first correspondence between temperature and time. The cooling capacity of the battery pack is measured according to the heat transfer coefficient. The established temperature model can better describe the first correspondence between the temperature of the temperature measurement points of the battery pack and time. The heat transfer coefficient obtained by fitting the first correspondence between temperature and time is relatively accurate. According to the heat transfer coefficient, the cooling capacity of the battery pack can be determined, and the battery packs with faults in the cooling system can be detected in time.

[0044] To facilitate the understanding of the technical solutions provided by the embodiments of the present application, the following will describe the method for detecting the cooling capacity of the battery pack provided by the embodiments of the present application with reference to the accompanying drawings.

[0045] SeeFigure 1 As shown in the figure, it is a schematic flowchart of a method for detecting the cooling capacity of a battery pack provided by an embodiment of the present application, including S101 - S104.

[0046] S101: In response to determining that the battery pack meets the establishment condition, establish a temperature model of the battery pack.

[0047] When the cooling system of the battery pack is operating stably, the heat generation process and heat dissipation process of the battery pack are relatively stable. At this time, the contour of the temperature field of the battery pack is relatively simple, and the isothermal surface is close to a plane. Refer to Figure 2 As shown in the figure, it is a schematic diagram of the temperature field of a battery pack provided by an embodiment of the present application. Among them, the positive direction of the x - axis is the vertically downward direction. The isothermal surface is approximately perpendicular to the x - axis. In this case, it is convenient to establish a temperature model describing the temperature field of the battery pack.

[0048] When the battery pack meets the establishment condition, establish a temperature model of the battery pack. Among them, the establishment condition is that the cooling system of the battery pack is operating stably.

[0049] In some possible implementation manners, the stable operation of the cooling system of the battery pack means that the operation duration of the cooling system of the battery pack exceeds the stable duration. Specifically, obtain the operation duration of the cooling system of the battery pack. When the operation duration of the cooling system exceeds the stable duration, it is determined that the cooling system is in a stable operation state, and the temperature field of the battery pack is relatively simple and stable. The present application embodiment does not limit the specific implementation manner of obtaining the operation duration of the cooling system of the battery pack. As an example, the battery pack management system of the vehicle can record the operation duration of the cooling system. As another example, the battery pack management system of the vehicle can record the start time of the cooling system. According to the start time of the cooling system and the current time, the operation duration of the cooling system is obtained. Further, during the operation of the cooling system, the temperature change of the battery pack obtained should be greater than the temperature measurement error value, so that a relatively accurate temperature of the battery pack can be obtained.

[0050] The temperature model of the battery pack is used to describe the temperature of the battery pack at different times. The temperature model of the battery pack is established based on the law of conservation of energy. When the cooling system of the battery pack is operating stably, the isothermal surface is close to a plane. The temperature model can be simplified to one - dimensional. The temperature model can be described by a one - dimensional heat conduction equation with initial conditions and boundary conditions.

[0051] The model parameters of the temperature model include the heat transfer coefficient from the coolant to the bottom surface of the battery. The heat transfer coefficient can be used to measure the cooling capacity of the cooling system.

[0052] In some possible implementation manners, the present application embodiment provides a temperature model describing the temperature field of the battery pack. The schematic of the temperature field of the battery pack is as Figure 2As shown, the upper surface of the battery pack is the plane of x = 0, and the lower surface of the battery pack is the plane of x = l. l is the height of the battery pack.

[0053] According to Figure 2 The temperature model established based on the structure of the battery pack shown is as shown in formula (1):

[0054]

[0055] Where is the heat conduction equation. T = T 0 |t = 0 is the initial condition. is the boundary condition. In the temperature model, ρ is the density of the battery pack, C p is the specific heat capacity at constant pressure, λ is the thermal conductivity of the battery pack in the vertical direction, q(T, t) is the heat generation power per unit volume. V is the volume of the battery pack. R(T) is the equivalent internal resistance of the battery under the condition of temperature T. R(T) ≈ (2.04·e -0.08·T + 0.724)·R′(25°C). T 0 is the initial temperature of the battery pack. T 1 is the coolant temperature. h is the heat transfer coefficient from the coolant to the bottom surface of the battery. l is the height of the battery pack. °C is Celsius. I(t) is the current of the battery pack.

[0056] In the temperature model, ρ, C p , l, λ, V, T 0 , I(t) are known quantities. The known quantities can be determined by measurement or according to the basic parameter information of the battery pack. While R(25°C), h and T 1 are unknown quantities to be determined.

[0057] S102: Obtain the first correspondence between the temperature and time of the temperature measurement points of the battery pack using the temperature model.

[0058] The temperature model can describe the first correspondence between the temperature and time of the battery pack. According to the positions of the temperature measurement points of the battery pack in the battery pack, the first correspondence between the temperature measurement points and time of the battery pack can be obtained using the temperature model.

[0059] It should be noted that the first correspondence between the temperature measurement points and time of the battery pack obtained according to the temperature model is only a theoretical correspondence. After establishing the temperature model, it is also necessary to train the temperature model according to the second correspondence between the temperature and time of the temperature measurement points of the battery pack obtained by actual measurement to determine the model parameters included in the temperature model.

[0060] Solve formula (1) to obtain the first correspondence between the temperature and time of the temperature measurement points of the battery pack. In addition, Figure 2Taking the structure of the battery pack shown and the above temperature model as an example, the temperature measurement point of the battery pack is located on the upper surface of the battery pack. Therefore, the first correspondence between the temperature of the temperature measurement point of the battery pack and time, that is, the correspondence between the temperature of the upper surface of the battery pack and time. Therefore, substituting x = 0 into the formula, we get formula (2).

[0061]

[0062] where ε n is the root of the equation ε n , ρ, C p , l, λ, V, T 0 , I(t) are known quantities. R(25°C), h and T 1 are unknown quantities to be determined.

[0063] S103: Fit the heat transfer coefficient using the first correspondence between temperature and time.

[0064] The model parameters in the temperature model are all fixed values. The first correspondence between the temperature of the temperature measurement point obtained using the temperature model and time is used to fit the heat transfer coefficient.

[0065] In a possible implementation, taking the first correspondence between the temperature of the temperature measurement point obtained using the above temperature model and time as an example, the first correspondence between the temperature of the temperature measurement point and time includes unknown quantities to be determined. The unknown quantities to be determined include R(25°C), h and T 1 .

[0066] where T 1 can be determined according to the coolant temperature after the cooling system stabilizes under normal circumstances. As some examples, according to the thermal management strategy of the battery pack, it can be obtained that in a battery pack operating stably, the coolant temperature is generally 25 degrees Celsius. The value of R(25°C) with the largest probability is 2.6 milliohms.

[0067] The heat transfer coefficient can be fitted using the second correspondence between the temperature of the temperature measurement point and time and the first correspondence between temperature and time.

[0068] In a possible implementation, the process of fitting the heat transfer coefficient includes the following three steps.

[0069] A1: Obtain the second correspondence between the temperature of the temperature measurement point and time.

[0070] The second correspondence between the temperature of the temperature measurement point and time is determined by measurement. Specifically, the temperature of the temperature measurement point of the battery pack at different times is obtained to obtain the second correspondence between temperature and time.

[0071] A2: Fit the heat transfer coefficient by using the second correspondence between the temperature and time and the first correspondence between the temperature and time, and obtain a fitting result.

[0072] Fit the heat transfer coefficient by using the second correspondence and the first correspondence, and obtain multiple fitting results.

[0073] The embodiments of the present application do not limit the method for fitting the heat transfer coefficient. For example, the least squares curve fitting method in the curve fitting method.

[0074] A3: Determine the heat transfer coefficient according to the fitting evaluation index and the fitting result.

[0075] The fitting evaluation index is used to measure the gap between the first correspondence between the temperature and time and the second correspondence between the temperature and time. As some examples, the fitting evaluation index is the mean square error. See Figure 3 As shown, this figure is a schematic diagram of the distribution of a fitting result provided by an embodiment of the present application.

[0076] In some possible implementation manners, the heat transfer coefficient corresponding to the fitting evaluation index lower than the loss threshold in the fitting result is determined as the heat transfer coefficient of the battery pack. In another possible implementation manner, the heat transfer coefficient corresponding to the minimum fitting evaluation index in the fitting result is determined as the heat transfer coefficient of the battery pack.

[0077] The above process of fitting the heat transfer coefficient of the battery pack does not consider the influence of the SOC (state of charge) on the heat generation capacity of the battery pack.

[0078] Further, after fitting the heat transfer coefficient of the battery pack, the heat transfer coefficient can be corrected based on different SOCs.

[0079] In some possible implementation manners, obtain the average SOC of the battery pack. The average SOC of the battery pack is the average value of the SOC of the battery pack during the process of fitting the heat transfer coefficient of the battery pack. Establish the correspondence between the heat transfer coefficient of the fitted battery pack and the average SOC during the fitting process, and obtain a fitting function.

[0080] The fitting function can be obtained based on polynomial fitting. The fitting function is shown in Formula (3).

[0081]

[0082] Where n is a natural number, and the maximum value of n is k.

[0083] Correct the heat transfer coefficient of the battery pack based on the fitting function. The corrected heat transfer coefficient is shown in Formula (4).

[0084] hcorrect = h - h(soc) + h original_mean (4)

[0085] Wherein, h is the uncorrected heat transfer coefficient. h original_mean is the average value of the uncorrected heat transfer coefficients of multiple battery packs. h original_mean can be obtained by fitting the heat transfer coefficients of the battery packs multiple times.

[0086] S104: Determine the cooling capacity of the battery pack according to the heat transfer coefficient.

[0087] The heat transfer coefficient can measure the cooling capacity of the battery pack. In some possible implementation manners, the value range of the heat transfer coefficient can be determined in advance based on the cooling capacity of the battery pack. For example, a first threshold is determined in advance. The first threshold is used to determine that a failure occurs in the cooling capacity of the cooling system of the battery pack. After obtaining the heat transfer coefficient, the heat transfer coefficient is compared with the first threshold. If the heat transfer coefficient is lower than the first threshold, it is determined that a failure occurs in the cooling capacity of the battery pack. For another example, a first threshold and a second threshold are determined in advance. Wherein, the first threshold is used to determine that a failure occurs in the cooling capacity of the cooling system of the battery pack, and the second threshold is used to determine that the cooling capacity of the cooling system of the battery pack is poor. The heat transfer coefficient is compared with the first threshold and the second threshold respectively. If the heat transfer coefficient is less than the first threshold, it indicates that a failure occurs in the cooling system. If the heat transfer coefficient is greater than the first threshold and less than the second threshold, it indicates that the operation of the cooling system is poor. If the heat transfer coefficient is greater than the second threshold, it indicates that the operation of the cooling system is good.

[0088] Based on the relevant content of the above S101 - S104, it can be known that when it is determined that the battery pack meets the establishment condition, a temperature model of the battery pack is established. Using the temperature model, the first correspondence between the temperature and time of the temperature measurement points of the battery pack can be obtained. Then, the heat transfer coefficient is obtained by fitting the first correspondence between the temperature and time. The cooling capacity of the battery pack is measured according to the heat transfer coefficient. The established temperature model can better describe the first correspondence between the temperature and time of the temperature measurement points of the battery pack. The heat transfer coefficient obtained by fitting the first correspondence between the temperature and time is relatively accurate. According to the heat transfer coefficient, the cooling capacity of the battery pack can be determined, and the battery packs with failures in the cooling system can be discovered in time.

[0089] Based on the detection method for the cooling capacity of a battery pack provided in the above method embodiment, the embodiment of the present application further provides a detection device for the cooling capacity of a battery pack. The detection device for the cooling capacity of a battery pack will be described below with reference to the accompanying drawings.

[0090] See Figure 4 , this figure is a schematic structural diagram of a detection device for the cooling capacity of a battery pack provided in the embodiment of the present application. As Figure 4As shown in the figure, the detection device for the cooling capacity of the battery pack includes:

[0091] A establishing unit 401, configured to establish a temperature model of the battery pack in response to determining that the battery pack meets the establishing condition, where the temperature model is used to describe the correspondence between the temperature of the battery pack and time, and the model parameters of the temperature model include a heat transfer coefficient, and the heat transfer coefficient is the heat transfer coefficient from the coolant to the bottom surface of the battery;

[0092] A calculating unit 402, configured to obtain a first correspondence between the temperature and time of the temperature measurement point of the battery pack by using the temperature model;

[0093] A fitting unit 403, configured to fit and obtain the heat transfer coefficient by using the first correspondence between the temperature and time;

[0094] A determining unit 404, configured to determine the cooling capacity of the battery pack according to the heat transfer coefficient.

[0095] In a possible implementation manner, the establishing condition is that the cooling system of the battery pack operates stably.

[0096] In a possible implementation manner, the stable operation of the battery pack means that the operation duration of the cooling system of the battery pack exceeds the stable duration.

[0097] In a possible implementation manner, the heat transfer coefficient is an unknown quantity to be determined, and the fitting unit 403 is configured to obtain a second correspondence between the temperature and time of the temperature measurement point, where the second correspondence is determined by measurement; fit the heat transfer coefficient by using the second correspondence between the temperature and time and the first correspondence between the temperature and time to obtain a fitting result; determine the heat transfer coefficient according to the fitting evaluation index and the fitting result, and the fitting evaluation index is used to measure the gap between the first correspondence between the temperature and time and the second correspondence between the temperature and time.

[0098] In a possible implementation manner, the fitting evaluation index is the mean square error.

[0099] In a possible implementation manner, the determining unit 404 is configured to determine that the cooling capacity of the battery pack fails when the heat transfer coefficient is lower than a first threshold.

[0100] Based on the detection method for the cooling capacity of the battery pack provided in the above method embodiment, the embodiment of the present application further provides a detection device for the cooling capacity of the battery pack, including: a processor, a memory, and a system bus;

[0101] The processor and the memory are connected through the system bus;

[0102] The memory is used to store one or more programs, and the one or more programs include instructions, which, when executed by the processor, cause the processor to execute the method for detecting the battery pack cooling capacity described in any one of the above embodiments.

[0103] Based on the method for detecting the battery pack cooling capacity provided in the above method embodiments, the present application provides a computer-readable storage medium, in which instructions are stored, and when the instructions are run on a terminal device, the terminal device is caused to execute the method for detecting the battery pack cooling capacity described in any one of the above embodiments.

[0104] It should be noted that the various embodiments in this specification are described in a progressive manner, and the key point of each embodiment is to illustrate the differences from other embodiments. The same or similar parts among the various embodiments can be referred to each other. For the systems or devices disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple, and the relevant parts can be referred to the description of the method part.

[0105] It should be understood that in the present application, "at least one (item)" means one or more, and "a plurality" means two or more. "And / or" is used to describe the association relationship of associated objects, indicating that three relationships can exist. For example, "A and / or B" can mean: only A exists, only B exists, and both A and B exist at the same time. Among them, A and B can be singular or plural. The character " / " generally means that the associated objects before and after are in an "or" relationship. "At least one (one) of the following" or its similar expression means any combination of these items, including any combination of single item (one) or plural items (ones). For example, at least one (one) of a, b, or c can mean: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, c can be single or multiple.

[0106] It should also be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "including a..." does not exclude the existence of another identical element in the process, method, article or device including the element.

[0107] The steps of the methods or algorithms described in connection with the embodiments disclosed herein may be implemented directly in hardware, in a software module executed by a processor, or in a combination thereof. The software module may be disposed in a random access memory (RAM), a memory, a read-only memory (ROM), an electrically programmable ROM, an electrically erasable programmable ROM, a register, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art.

[0108] The foregoing description of the disclosed embodiments enables those skilled in the art to make or use the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for detecting the cooling capacity of a battery pack, characterized in that, the method includes: In response to determining that the battery pack meets the establishment condition, a temperature model of the battery pack is established. The temperature model is used to describe the correspondence between the temperature of the battery pack and time. The model parameters of the temperature model include a heat transfer coefficient, and the heat transfer coefficient is the heat transfer coefficient from the coolant to the bottom surface of the battery; the temperature model includes a calculation formula constructed by known quantities and unknown quantities to be determined. The known quantities include the density of the battery pack, the mass specific heat capacity, the height of the battery pack, the thermal conductivity of the battery pack in the vertical direction, the volume of the battery pack, the initial temperature of the battery pack, and the current of the battery pack. The unknown quantities to be determined include the equivalent internal resistance of the battery under temperature T, the heat transfer coefficient, and the coolant temperature; Obtain the first correspondence between the temperature and time of the temperature measurement point of the battery pack by using the temperature model; the temperature measurement point of the battery pack is located on the upper surface of the battery pack; Fitting the heat transfer coefficient by using the first correspondence between temperature and time includes: obtaining the second correspondence between the temperature and time of the temperature measurement point, and the second correspondence is determined by measurement; fitting the heat transfer coefficient by using the second correspondence between temperature and time and the first correspondence between temperature and time to obtain a fitting result; determining the heat transfer coefficient according to the fitting evaluation index and the fitting result, and the fitting evaluation index is used to measure the gap between the first correspondence between temperature and time and the second correspondence between temperature and time; Determine the cooling capacity of the battery pack according to the heat transfer coefficient.

2. The method according to claim 1, characterized in that, the establishment condition is that the cooling system of the battery pack operates stably.

3. The method according to claim 2, characterized in that, the battery pack operates stably when the operation duration of the cooling system of the battery pack exceeds the stable duration.

4. The method according to claim 1, characterized in that, the fitting evaluation index is the mean square error.

5. The method according to claim 1, characterized in that, determining the cooling capacity of the battery pack according to the heat transfer coefficient includes: When the heat transfer coefficient is lower than the first threshold, it is determined that the cooling capacity of the battery pack fails.

6. The method according to claim 1, characterized in that, the method further includes: Obtain the average state of charge of the battery pack; Correct the heat transfer coefficient based on the average state of charge to obtain a corrected heat transfer coefficient.

7. A detection device for the cooling capacity of a battery pack, characterized in that, the device includes: A building unit, configured to build a temperature model of the battery pack in response to determining that the battery pack meets the building condition, where the temperature model is used to describe the correspondence between the temperature of the battery pack and time, and the model parameters of the temperature model include a heat transfer coefficient, and the heat transfer coefficient is the heat transfer coefficient from the coolant to the bottom surface of the battery; the temperature model includes a calculation formula constructed by known quantities and unknown quantities to be determined, the known quantities include the density of the battery pack, the mass specific heat capacity, the height of the battery pack, the thermal conductivity of the battery pack in the vertical direction, the volume of the battery pack, the initial temperature of the battery pack, and the current of the battery pack, and the unknown quantities to be determined include the equivalent internal resistance of the battery at temperature T, the heat transfer coefficient, and the coolant temperature; A calculation unit, configured to obtain a first correspondence between the temperature and time of the temperature measurement point of the battery pack by using the temperature model; the temperature measurement point of the battery pack is located on the upper surface of the battery pack; A fitting unit, configured to fit and obtain the heat transfer coefficient by using the first correspondence between the temperature and time; The fitting unit is configured to obtain a second correspondence between the temperature and time of the temperature measurement point, where the second correspondence is determined by measurement; fit the heat transfer coefficient by using the second correspondence between the temperature and time and the first correspondence between the temperature and time to obtain a fitting result; determine the heat transfer coefficient according to a fitting evaluation index and the fitting result, where the fitting evaluation index is used to measure the gap between the first correspondence between the temperature and time and the second correspondence between the temperature and time; A determination unit, configured to determine the cooling capacity of the battery pack according to the heat transfer coefficient.

8. A detection device for the cooling capacity of a battery pack, characterized in that, it includes: a processor, a memory, and a system bus; the processor and the memory are connected through the system bus; the memory is configured to store one or more programs, and the one or more programs include instructions, and when the instructions are executed by the processor, the processor executes the method according to any one of claims 1-6.

9. A computer-readable storage medium, characterized in that, the computer-readable storage medium stores instructions, and when the instructions run on a terminal device, the terminal device executes the method according to any one of claims 1-6.

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