A battery pack fault detection method, device, apparatus and medium

Abstract

The application discloses a battery pack fault detection method, device, equipment and medium. 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 corresponding relationship between the temperature of the battery pack and time. The temperature model is established based on a heat generation process and a heat dissipation process. The model parameters of the temperature model include a heat coefficient. The heat coefficient includes a first heat generation coefficient, a second heat generation coefficient, a first heat transfer coefficient and a second heat transfer coefficient. The temperature model is used to obtain a first corresponding relationship between the temperature of a temperature measuring point of the battery pack and time. The heat coefficient is determined by fitting the first corresponding relationship between the temperature and time. Finally, whether the battery pack has a fault is determined according to the heat coefficient. The heat coefficient obtained by fitting the first corresponding relationship between the temperature and time is relatively accurate, and whether the battery pack has a fault in terms of temperature can be determined according to the heat coefficient.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of detection, and particularly relates to a battery pack fault detection method, device, equipment and medium. BACKGROUND

[0002] A battery pack is arranged in a vehicle. The battery pack is used to store electric energy and provide electric energy for the vehicle so that the vehicle can run normally. The temperature of the battery pack changes with the running state of the vehicle and to some extent reflects the state of the battery pack.

[0003] The temperature of the battery pack is affected by the running state of the vehicle and the external environment. Since the running state of the vehicle is relatively complex and the external environment is also relatively difficult to control, it is difficult to measure the state of the battery pack according to the measured temperature of the battery pack. In some cases, the temperature of the normally running battery pack can also exceed the temperature threshold. Therefore, how to more accurately detect whether the battery pack has a fault in terms of temperature is a technical problem to be solved. SUMMARY

[0004] Therefore, the present application provides a battery pack fault detection method, device, equipment and medium, which can more accurately determine whether the battery pack has a fault in terms of temperature.

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

[0006] In a first aspect, the present application provides a battery pack fault detection method, which comprises:

[0007] 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 corresponding relationship between the temperature of the battery pack and time, the model parameters of the temperature model include a heat coefficient, the heat coefficient includes a first heat generation coefficient, a second heat generation coefficient, a first heat transfer coefficient and a second heat transfer coefficient, the first heat transfer coefficient is the heat transfer coefficient of the cooling liquid to the battery bottom surface when the liquid cooling system is closed, and the second heat transfer coefficient is the heat transfer coefficient of the cooling liquid to the battery bottom surface when the liquid cooling system is opened;

[0008] The temperature model is used to obtain a first corresponding relationship between the temperature of a temperature measuring point of the battery pack and time;

[0009] The heat coefficient is determined by fitting the first corresponding relationship between the temperature and time;

[0010] Whether the battery pack has a fault is determined according to the heat coefficient.

[0011] In a possible implementation, the temperature model is obtained according to a temperature-time correspondence of an upper boundary point of the battery pack, a temperature-time correspondence of at least one inner point between the upper boundary point and a lower boundary point of the battery pack, and a temperature-time correspondence of the lower boundary point.

[0012] In a possible implementation, the fitting of the heat coefficient by using the first temperature-time correspondence includes:

[0013] obtaining a second temperature-time correspondence of the temperature measuring point, the second temperature-time correspondence being measured and determined;

[0014] fitting the heat coefficient by using the second temperature-time correspondence and the first temperature-time correspondence to obtain a fitting result;

[0015] determining the heat coefficient according to a fitting evaluation index and the fitting result, the fitting evaluation index being used to measure a gap between the first temperature-time correspondence and the second temperature-time correspondence.

[0016] In a possible implementation, the determining of whether the battery pack has a fault according to the heat coefficient includes:

[0017] in response to the heat coefficient being lower than a first threshold, determining that the battery pack has a fault.

[0018] In a possible implementation, the establishment condition is that the battery pack is stable.

[0019] In a possible implementation, the stability of the battery pack is that a running duration of the battery is longer than a stable duration.

[0020] In a second aspect, the present application provides a battery pack fault detection device, the device comprising:

[0021] an establishment unit configured to, in response to determining that a battery pack meets an establishment condition, establish a temperature model of the battery pack, the temperature model being used to describe a temperature-time correspondence of the battery pack, and model parameters of the temperature model including a heat coefficient, the heat coefficient including a first heat generation coefficient, a second heat generation coefficient, a first heat transfer coefficient, and a second heat transfer coefficient, the first heat transfer coefficient being a heat transfer coefficient of cooling liquid to a bottom surface of the battery when a liquid cooling system is turned off, and the second heat transfer coefficient being a heat transfer coefficient of the cooling liquid to the bottom surface of the battery when the liquid cooling system is turned on;

[0022] a determination unit configured to obtain a first temperature-time correspondence of a temperature measuring point of the battery pack by using the temperature model;

[0023] a fitting unit configured to fit the heat coefficient by using the first correspondence between the temperature and the time;

[0024] a detecting unit configured to determine whether the battery pack has a fault according to the heat coefficient.

[0025] In a possible implementation, the temperature model is obtained according to a correspondence between a temperature of an upper boundary point of the battery pack and time, a correspondence between a temperature of at least one inner point and time, and a correspondence between a temperature of a lower boundary point of the battery pack and time, the inner point being a point between the upper boundary point and the lower boundary point of the battery pack.

[0026] In a possible implementation, the fitting unit is configured to obtain a second correspondence between the temperature of the temperature measuring point and the time, the second correspondence being measured and determined; fit the heat coefficient by using the second correspondence between the temperature and the time and the first correspondence between the temperature and the time to obtain a fitting result; and determine the heat coefficient according to a fitting evaluation index and the fitting result, the fitting evaluation index being used to measure a gap between the first correspondence between the temperature and the time and the second correspondence between the temperature and the time.

[0027] In a possible implementation, the detecting unit is configured to determine that the battery pack has a fault in response to the heat coefficient being lower than a first threshold.

[0028] In a possible implementation, the condition is that the battery pack is stable.

[0029] In a possible implementation, the battery pack being stable means that a running duration of the battery pack is longer than a stable duration.

[0030] In a third aspect, the present application provides a battery pack fault detection device, comprising: 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, the one or more programs comprising instructions that, when executed by the processor, cause the processor to perform the method of the first aspect.

[0033] In a fourth aspect, the present application provides a computer readable storage medium, the computer readable storage medium storing instructions, when the instructions are run on a terminal device, causing the terminal device to perform the method of the first aspect.

[0034] Therefore, the present application has the following beneficial effects:

[0035] The application provides a battery pack fault detection method, device, equipment and medium. In response to determining that a battery pack meets establishment conditions, a temperature model of the battery pack is established. The temperature model is used to describe the corresponding relationship between the temperature of the battery pack and time. The temperature model is established based on heat generation and heat dissipation processes. Model parameters of the temperature model include heat coefficients. The heat coefficients include a first heat generation coefficient, a second heat generation coefficient, a first heat transfer coefficient and a second heat transfer coefficient. The temperature model is used to obtain a first corresponding relationship between the temperature of a temperature measurement point of the battery pack and time. The heat coefficients are determined by fitting the first corresponding relationship between the temperature and time. Finally, whether the battery pack has a fault is determined according to the heat coefficients. The heat coefficients obtained by fitting the first corresponding relationship between the temperature and time are relatively accurate, and whether the battery pack has a fault in terms of temperature can be determined according to the heat coefficients. BRIEF DESCRIPTION OF DRAWINGS

[0036] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0037] Figure 1 A flowchart of a battery pack fault detection method provided by an embodiment of the present application;

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

[0039] Figure 3 A structural schematic diagram of a battery pack fault detection device provided by an embodiment of the present application. DETAILED DESCRIPTION

[0040] In order to facilitate understanding and explaining the technical solutions provided by the embodiments of the present application, the background art of the present application will be described first.

[0041] The battery pack of a vehicle generates a certain amount of heat during operation. The cooling system of the battery pack can conduct excess heat, so that the battery pack works within a normal temperature range. The temperature of the battery pack can reflect the operation of the cooling system to some extent. However, the temperature of the battery pack is influenced by many factors, and it is difficult to accurately determine whether the battery pack has a fault only by the temperature of the battery pack.

[0042] Based on this, the application provides a battery pack fault detection method, device, equipment and medium. 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 corresponding relationship between the temperature of the battery pack and time. The temperature model is established based on the heat generation process and the heat dissipation process. The model parameters of the temperature model include a heat coefficient. The heat coefficient includes a first heat generation coefficient, a second heat generation coefficient, a first heat transfer coefficient and a second heat transfer coefficient. The temperature model is used to obtain a first corresponding relationship between the temperature of a temperature measuring point of the battery pack and time. The heat coefficient is determined by fitting the first corresponding relationship between the temperature and time. Finally, whether the battery pack has a fault is determined according to the heat coefficient. The heat coefficient obtained by fitting the first corresponding relationship between the temperature and time is relatively accurate, and the heat coefficient can be used to determine whether the battery pack has a fault in terms of temperature.

[0043] In order to facilitate understanding of the technical solutions provided by the embodiments of the application, the battery pack fault detection method provided by the embodiments of the application will be described below with reference to the accompanying drawings.

[0044] Referring to Figure 1 , the figure is a flowchart of a battery pack fault detection method provided by an embodiment of the application, including S101-S104.

[0045] S101: In response to determining that the battery pack meets the establishment condition, a temperature model of the battery pack is established.

[0046] In the case that the cooling system of the battery pack is stable, the heat generation process and the heat dissipation process of the battery pack are relatively stable. At this time, the profile of the temperature field of the battery pack is relatively simple, and the isothermal surface is close to a plane. Referring to Figure 2 , the figure is a schematic diagram of a battery pack temperature field provided by an embodiment of the application. 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 for describing the temperature field of the battery pack.

[0047] When the battery pack meets the establishment condition, the temperature model of the battery pack is established. The establishment condition is that the cooling system of the battery pack is stable.

[0048] In some possible implementation manners, the running stability of the cooling system of the battery pack is that the running time of the cooling system of the battery pack exceeds a stable time. Specifically, the running time of the cooling system of the battery pack is obtained. When the running time of the cooling system exceeds the stable time, it is determined that the cooling system is in a running stable state, and the temperature field of the battery pack is relatively simple and stable. The embodiments of the present application do not limit the specific implementation manners of obtaining the running time of the cooling system of the battery pack. As an example, the battery pack management system of the vehicle can record the running time of the cooling system. As another example, the battery pack management system of the vehicle can record the time when the cooling system starts. According to the time when the cooling system starts and the current time, the running time of the cooling system is obtained.

[0049] 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 runs stably, the isothermal surface approaches a plane. The temperature model can be simplified to one dimension.

[0050] In some possible implementation manners, the embodiments of the present application provide a temperature model for describing the temperature field of the battery pack. The structure of the battery pack is shown in Figure 2 , where 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.

[0051] The temperature model can be established based on the principle that the heat generation process and the heat transfer process are balanced when the battery pack runs stably. As an example, the temperature model includes a heat generation part and a heat transfer part.

[0052] The heat generation part of the temperature model can be determined based on the power of the battery pack.

[0053] The heat transfer part of the temperature model can be represented by the temperatures of several key points in the battery pack. The embodiments of the present application do not limit the key points in the battery pack used to establish the heat transfer part of the temperature model. For example, the upper boundary point, the lower boundary point and at least one inner point of the battery pack can be selected as the key points. The inner point is a point inside the battery pack, and is a point on the plane between the upper boundary surface and the lower boundary surface of the battery pack. It should be noted that when the cooling system of the battery pack runs stably, the isothermal surface approaches a plane. The temperatures of the points in the same plane can be considered to be the same. The embodiments of the present application do not limit the number of inner points selected from different planes. The inner points of different planes can be one or more.

[0054] The heat transfer part of the temperature model is established based on the upper boundary point, the lower boundary point and one inner point of the battery pack. The inner point used to establish the heat transfer part of the temperature model is in the plane of the middle height of the battery pack.

[0055] The temperature description for the upper boundary point is represented by equation (1):

[0056]

[0057] where T0(t) is the temperature of the upper boundary point at time t, P(t) is the battery heat generation power, V is the battery volume, T1(t) is the temperature of the inner point at time t, dl is the distance between two points, λ is the battery thermal conductivity, ρ is the battery density, C p is the mass specific heat capacity.

[0058] The temperature description for the inner point is represented by equation (2):

[0059]

[0060] The temperature description for the lower boundary point is represented by equation (3):

[0061]

[0062] where the lower boundary point is closer to the liquid cooling system, T(t) is the cooling liquid temperature. T2(t) is the temperature of the inner point at time t. h1 is the first heat transfer coefficient, which is the heat transfer coefficient from the cooling liquid to the bottom surface of the battery when the liquid cooling system is off. h1 + h2 is the second heat transfer coefficient, which is the heat transfer coefficient from the cooling liquid to the bottom surface of the battery when the liquid cooling system is on. s(t) is the liquid cooling system request time sequence of the battery pack, taking the value of 1 when the liquid cooling system is on and 0 when the liquid cooling system is off.

[0063] Based on the above equations (1)-(3), the heat transfer part of the temperature model is obtained by solving the recursive relationship in a discretized form, which is equation (4).

[0064]

[0065] The above example is described with one inner point. As another example, the key points for establishing the heat transfer part of the temperature model include multiple inner points.

[0066] The temperature description for the upper boundary point is represented by equation (5):

[0067]

[0068] where T0(t) is the temperature of the upper boundary point at time t, P(t) is the battery heat generation power, V is the battery volume, T1(t) is the temperature of the first inner point at time t, dl is the distance between two points, λ is the battery thermal conductivity.

[0069] The temperature description for the nth inner point is represented by equation (6):

[0070]

[0071] where T n (t) is the temperature of the nth inner point at time t.

[0072] For the temperature description of the lower boundary point, it is represented by formula (7):

[0073]

[0074] where the lower boundary point is located in the cooling liquid, and T(t) is the cooling liquid temperature. T N (t) is the temperature of the lower boundary point at time t. N is equal to the total number of inner points plus 1.

[0075] S102: Obtain the first correspondence between the temperature of the temperature measuring point of the battery pack and time by using the temperature model.

[0076] The temperature model can describe the correspondence between the temperature of the battery pack and time. According to the position of the temperature measuring point of the battery pack in the battery pack, the first correspondence between the temperature measuring point of the battery pack and time can be obtained by using the temperature model.

[0077] It should be noted that the first correspondence between the temperature measuring point of the battery pack and time obtained according to the temperature model is only a theoretical correspondence. After establishing the temperature model, the temperature model needs to be trained according to the second correspondence between the temperature of the temperature measuring point of the battery pack and time actually measured, to determine the model parameters included in the temperature model.

[0078] Taking the heat transfer model of the temperature model described by formula (4) as an example, which is determined according to the upper boundary point, one inner point and the lower boundary point as key points, the first correspondence between the temperature measuring point of the battery pack and time is obtained. Wherein, the temperature measuring point of the battery pack is located at the upper boundary point of the battery pack.

[0079] Formula (4) can be solved as a linear equation set, and the solving formula is shown in formula (8).

[0080]

[0081] Solving by using the linear relationship can improve the solving speed. The expression of T0(t) is obtained by solving, that is, the first correspondence between the temperature of the temperature measuring point of the battery pack and time.

[0082] T0(t) calculated according to formula (8) is based on the description of the heat transfer process, including two unknown quantities h1 and h2.

[0083] In addition, according to the heat generation part of the temperature model, another expression of T0(t) can be obtained, as shown in formula (9).

[0084] T0(t) = f3(P(t), T(t), s(t), At(t), T0(t - 1)) (9)

[0085] where P(t) is the total heat generation power time series. At(t) is the time interval time series.

[0086] P(t) is represented by equation (10).

[0087] P(t) = P1(t) + P2(t) (10)

[0088] P1(t) is the polarization heat generation power time series. P2(t) is the entropy change heat generation power time series.

[0089] P1(t) is represented by equation (11).

[0090] P1(t) = [OCV(t) - u(t)] * I(t) (11)

[0091] where OCV(t) is the open circuit voltage time series. u(t) is the voltage time series. I(t) is the current time series.

[0092] OCV(t) is measured according to the SOC-OCV experiment and the single cell cycling experiment in the constant temperature room. OCV(t) is represented by equation (12).

[0093]

[0094] SOC(t) is the SOC (State of charge) time series. i1 and a i2 are determined parameters. In one possible implementation, a i1 and a i2 are obtained by Kalman filtering according to the confidence degree of the experimental data of the SOC-OCV experiment and the single cell cycling experiment in the constant temperature room. β1 is the first heat generation coefficient, which is an unknown quantity.

[0095] P2(t) is represented by equation (13).

[0096] P2(t) = P s (t) * I(t) (13)

[0097] where P s (t) is the entropy change heat generation power time series under the condition of 1 ampere. I(t) is the current time series.

[0098] P s (t) is represented by equation (14).

[0099]

[0100] SOC(t) is the SOC time series.b i1 and b i2 are determined parameters. In one possible implementation, b i1 and b i2 are obtained by Kalman filtering according to the confidence degree of experimental data of the SOC-OCV experiment and the monomer battery cycle experiment in the constant-temperature room. β2 is the second heat generation coefficient, which is an unknown quantity.

[0101] It should be noted that the first correspondence obtained by the above example is that the temperature measurement point is on the upper boundary surface, and the heat transfer part of the temperature model is established according to the upper boundary point, the lower boundary point and an inner point on the middle plane. The embodiments of the present application do not limit the position of the temperature measurement point and the specific representation form of the first correspondence. Based on the above calculation method, the first correspondence in other cases can be calculated, which will not be described here again.

[0102] S103: fitting the heat generation coefficient by using the first correspondence between the temperature and the time.

[0103] The model parameters in the temperature model are all fixed values. The heat generation coefficient is fitted by using the first correspondence between the temperature and the time of the temperature measurement point obtained by the temperature model.

[0104] The heat generation coefficient can be fitted by using the second correspondence between the temperature and the time and the first correspondence between the temperature and the time.

[0105] In one possible implementation, the process of fitting the heat generation coefficient includes the following three steps.

[0106] A1: obtaining the second correspondence between the temperature and the time of the temperature measurement point.

[0107] The second correspondence between the temperature and the time of the temperature measurement point is determined by measurement. Specifically, the temperature of the battery pack temperature measurement point at different time is obtained to obtain the second correspondence between the temperature and the time.

[0108] A2: fitting the heat generation coefficient by using the second correspondence between the temperature and the time and the first correspondence between the temperature and the time, to obtain a fitting result.

[0109] The fitting of the heat generation coefficient by using the second correspondence and the first correspondence obtains a plurality of fitting results.

[0110] It should be noted that the heat coefficients include the first heat generation coefficient, the second heat generation coefficient, the first heat transfer coefficient and the second heat transfer coefficient. The embodiments of the present application do not limit the fitting determination manner of determining the four coefficients included in the heat coefficients. In one possible implementation manner, the four coefficients can be determined together. As an example, the heat coefficients are determined by fitting the second correspondence relationship between the temperature and the time and the first correspondence relationship between the temperature and the time. In another possible implementation manner, the four coefficients can be determined respectively. As an example, the first heat transfer coefficient and the second heat transfer coefficient are determined by fitting the static condition when the current is 0. After the first heat transfer coefficient and the second heat transfer coefficient are determined, the first heat transfer coefficient and the second heat transfer coefficient are taken as known quantities, and the first heat generation coefficient and the second heat generation coefficient are determined by fitting the condition when the current is not 0.

[0111] The embodiments of the present application do not limit the method of fitting the heat coefficients, for example, the least square curve fitting method in the curve fitting method.

[0112] A3: determining the heat coefficients according to the fitting evaluation index and the fitting result.

[0113] The fitting evaluation index is used to measure the gap between the first correspondence relationship between the temperature and the time and the second correspondence relationship between the temperature and the time. As some examples, the fitting evaluation index is the mean square error.

[0114] In some possible implementation manners, the heat coefficients with the corresponding fitting evaluation indexes in the fitting result lower than the loss threshold are determined as the heat coefficients of the battery pack. In another possible implementation manner, the heat coefficients with the minimum corresponding fitting evaluation indexes in the fitting result are determined as the heat coefficients of the battery pack.

[0115] S104: determining whether a fault exists in the battery pack according to the heat coefficients.

[0116] The heat coefficients can measure the heat generation and heat transfer capabilities of the battery pack.

[0117] In some possible implementation manners, the heat coefficients can be determined in advance based on data of normal operation of the battery pack. For example, a first threshold is determined in advance. The first threshold includes thresholds corresponding to the first heat generation coefficient, the second heat generation coefficient, the first heat transfer coefficient and the second heat transfer coefficient respectively. The first threshold is used to determine whether the battery pack has a fault. After obtaining the heat coefficients, the heat coefficients are compared with the first threshold. If the heat coefficients are lower than the first threshold, it is determined that the battery pack has a fault. In some possible implementation manners, when more than a target number of coefficients in the heat coefficients are less than the corresponding thresholds, it is determined that the battery pack has a fault. For example, when more than two coefficients in the heat coefficients are less than the corresponding thresholds, it is determined that the battery pack has a fault. For another example, a first threshold and a second threshold are determined in advance. The first threshold is used to determine whether the battery pack has a fault, and the second threshold is used to determine whether the battery pack has an abnormality. The first threshold includes thresholds corresponding to the first heat generation coefficient, the second heat generation coefficient, the first heat transfer coefficient and the second heat transfer coefficient respectively. The second threshold includes thresholds corresponding to the first heat generation coefficient, the second heat generation coefficient, the first heat transfer coefficient and the second heat transfer coefficient respectively. The heat coefficients are compared with the first threshold and the second threshold respectively. If the heat coefficients are less than the first threshold, it is determined that the battery pack has a fault. If the heat coefficients are greater than the first threshold and less than the second threshold, it is determined that the battery pack has a poor operation. If the heat coefficients are greater than the second threshold, it is determined that the battery pack has a good operation.

[0118] Based on the related content of S101-S104, 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 temperature model is established based on the heat generation process and the heat dissipation process. The model parameters of the temperature model include heat coefficients. The heat coefficients include the first heat generation coefficient, the second heat generation coefficient, the first heat transfer coefficient and the second heat transfer coefficient. The temperature model is used to obtain a first correspondence between the temperature of the temperature measurement point of the battery pack and time. The heat coefficients are fitted and determined by using the first correspondence between the temperature and time. Finally, whether the battery pack has a fault is determined according to the heat coefficients. The heat coefficients fitted by using the first correspondence between the temperature and time are relatively accurate, and whether the battery pack has a fault in terms of temperature can be determined according to the heat coefficients.

[0119] Based on the battery pack fault detection method provided in the method embodiment, an embodiment of the present application further provides a battery pack fault detection device, which will be described below with reference to the accompanying drawings.

[0120] Referring to Figure 3 , the figure is a structural schematic diagram of a battery pack fault detection device provided by an embodiment of the present application. As Figure 3 indicated, the battery pack fault detection device includes:

[0121] The establishing unit 301 is configured to establish a temperature model of the battery pack in response to determining that the battery pack meets an establishing condition, the temperature model being used to describe a correspondence between a temperature of the battery pack and time, and model parameters of the temperature model including heat coefficients, the heat coefficients including a first heat generation coefficient, a second heat generation coefficient, a first heat transfer coefficient, and a second heat transfer coefficient, the first heat transfer coefficient being a heat transfer coefficient of a cooling liquid to a bottom surface of the battery when a liquid cooling system is turned off, and the second heat transfer coefficient being a heat transfer coefficient of the cooling liquid to the bottom surface of the battery when the liquid cooling system is turned on.

[0122] The determining unit 302 is configured to obtain a first correspondence between the temperature of the temperature measuring point of the battery pack and time by using the temperature model.

[0123] The fitting unit 303 is configured to fit and determine the heat coefficients by using the first correspondence between the temperature and time.

[0124] The detecting unit 304 is configured to determine whether a fault exists in the battery pack according to the heat coefficients.

[0125] In a possible implementation, the temperature model is obtained according to a correspondence between a temperature of an upper boundary point of the battery pack and time, a correspondence between a temperature of at least one inner point and time, and a correspondence between a temperature of a lower boundary point and time, the inner point being a point between the upper boundary point and the lower boundary point of the battery pack.

[0126] In a possible implementation, the fitting unit 303 is configured to obtain a second correspondence between the temperature of the temperature measuring point and time, the second correspondence being measured and determined, fit the heat coefficients by using the second correspondence between the temperature and time and the first correspondence between the temperature and time to obtain a fitting result, and determine the heat coefficients according to a fitting evaluation index and the fitting result, the fitting evaluation index being used to measure a gap between the first correspondence between the temperature and time and the second correspondence between the temperature and time.

[0127] In a possible implementation, the detecting unit 304 is configured to determine that the battery pack has a fault in response to the heat coefficients being lower than a first threshold.

[0128] In a possible implementation, the establishing condition is that the battery pack is stable in operation.

[0129] In a possible implementation, the battery pack being stable in operation means that a running duration of the battery pack is longer than a stable duration.

[0130] Based on the battery pack fault detection method provided in the above method embodiments, the embodiment of the application further provides a battery pack fault detection device, comprising: a processor, a memory, a system bus;

[0131] The processor and the memory are connected through the system bus;

[0132] The memory is configured to store one or more programs, the one or more programs comprising instructions that, when executed by the processor, cause the processor to perform the battery pack fault detection method of any one of the above embodiments.

[0133] Based on the battery pack fault detection method provided in the above method embodiments, the embodiment of the application provides a computer-readable storage medium, the computer-readable storage medium storing instructions, when the instructions run on a terminal device, causing the terminal device to perform the battery pack fault detection method of any one of the above embodiments.

[0134] It should be noted that the embodiments in the specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts of each embodiment can be referred to each other. For the system or device disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple, and the relevant parts are described in the method part.

[0135] It should be understood that in the present application, "at least one" means one or more, and "multiple" means two or more. "And / or" is used to describe the association between the associated objects, which means that there can be three kinds of relationships, for example, "A and / or B" can represent three cases: only A, only B, and A and B exist at the same time, where A and B can be singular or plural. The character " / " generally represents an "or" relationship between the associated objects. "At least one of the following" or similar expressions means any combination of these items, including any combination of single or multiple items. For example, at least one of a, b or c can represent: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, and c can be single or multiple.

[0136] It is also to be noted that, as used in the specification and the appended claims, the singular forms "a," "an" and "the" include plural referents unless otherwise indicated. Furthermore, to the extent that the terms "including," "includes," "having," "has," "with," or "contains" are used in either the detailed description and the claims, such terms are intended to be inclusive in a manner similar to the term "comprising" as an open transition term without precluding any additional or other elements.

[0137] The embodiments disclosed herein can each be implemented as a method, apparatus, or article of manufacture using programming instructions. The embodiments disclosed herein can be implemented using software, firmware, hardware, or a combination thereof. The various elements of the disclosed embodiments, as well as the procedural aspects of the disclosed embodiments, can be implemented using a variety of programming instructions, software, firmware, or other programming instructions. In one embodiment, programming instructions are distributed via a computer medium, such as a compact disc, diskette, tape, file, or other computer medium. In another embodiment, programming instructions are downloaded into a computer from a network connection, such as the Internet, a local area network, a wide area network, or other network connection.

[0138] The above description of disclosed embodiments is intended to be illustrative and not restrictive. Many embodiments will be apparent to those of skill in the art upon reading and understanding the above description. The scope of the disclosure should, therefore, be determined not with reference to the above description, but instead with reference to the appended claims, along with their full scope of equivalents. What is claimed is:

Claims

1. A battery pack failure detection method, characterized by, The method comprises: in response to determining that the battery pack meets the establishment condition, establishing a temperature model of the battery pack, the temperature model being used to describe a correspondence between temperature and time of the battery pack, model parameters of the temperature model comprising heat coefficients, the heat coefficients comprising a first heat generation coefficient, a second heat generation coefficient, a first heat transfer coefficient and a second heat transfer coefficient, the first heat transfer coefficient being a heat transfer coefficient of cooling liquid to a battery bottom surface when a liquid cooling system is turned off, the second heat transfer coefficient being a heat transfer coefficient of cooling liquid to the battery bottom surface when the liquid cooling system is turned on, the establishment condition being that the battery pack is running stably, the temperature model being established based on a principle that a heat generation process and a heat transfer process are balanced when the battery pack is running stably, the first heat generation coefficient and the second heat generation coefficient being respectively coefficients related to a power at which the battery pack runs; obtaining, by using the temperature model, a first correspondence between temperature and time of a temperature measuring point of the battery pack; fitting and determining the heat coefficients by using the first correspondence between temperature and time, comprising: obtaining a second correspondence between temperature and time of the temperature measuring point, the second correspondence being determined by measurement; fitting the heat coefficients 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 coefficients according to a fitting evaluation index and the fitting result, the fitting evaluation index being used to measure a gap between the first correspondence between temperature and time and the second correspondence between temperature and time; determining whether a fault exists in the battery pack according to the heat coefficients.

2. The method of claim 1, wherein, The temperature model is obtained according to a correspondence between temperature and time of an upper boundary point of the battery pack, a correspondence between temperature and time of at least one inner point, and a correspondence between temperature and time of a lower boundary point, the inner point being a point between the upper boundary point and the lower boundary point of the battery pack.

3. The method of claim 1, wherein, The determining whether the fault exists in the battery pack according to the heat coefficients comprises: in response to the heat coefficients being lower than a first threshold value, determining that the battery pack has a fault.

4. The method of claim 1, wherein, The battery pack running stably means that the battery runs for a time longer than a stable time.

5. A battery pack failure detection apparatus characterized by comprising: The apparatus comprises: an establishment unit configured to, in response to determining that a battery pack meets an establishment condition, establish a temperature model of the battery pack, the temperature model being used to describe a correspondence between temperature and time of the battery pack, model parameters of the temperature model comprising heat coefficients, the heat coefficients comprising a first heat generation coefficient, a second heat generation coefficient, a first heat transfer coefficient and a second heat transfer coefficient, the first heat transfer coefficient being a heat transfer coefficient of cooling liquid to a battery bottom surface when a liquid cooling system is turned off, the second heat transfer coefficient being a heat transfer coefficient of cooling liquid to the battery bottom surface when the liquid cooling system is turned on, the establishment condition being that the battery pack is running stably, the temperature model being established based on a principle that a heat generation process and a heat transfer process are balanced when the battery pack is running stably, the first heat generation coefficient and the second heat generation coefficient being respectively coefficients related to a power at which the battery pack runs; a determination unit configured to obtain, by using the temperature model, a first correspondence between temperature and time of a temperature measuring point of the battery pack; The fitting unit is configured to fit the heat coefficient by using the first temperature-time correspondence relationship. The fitting unit is configured to obtain a second temperature-time correspondence relationship of the temperature measuring point, the second temperature-time correspondence relationship being measured and determined; fit the heat coefficient by using the second temperature-time correspondence relationship and the first temperature-time correspondence relationship to obtain a fitting result; and determine the heat coefficient according to a fitting evaluation index and the fitting result, the fitting evaluation index being used to measure a gap between the first temperature-time correspondence relationship and the second temperature-time correspondence relationship. The detecting unit is configured to determine whether the battery pack has a fault according to the heat coefficient.

6. The apparatus of claim 5, wherein, The temperature model is obtained according to a temperature-time correspondence relationship of an upper boundary point of the battery pack, a temperature-time correspondence relationship of at least one inner point between the upper boundary point and a lower boundary point of the battery pack, and a temperature-time correspondence relationship of the lower boundary point.

7. A battery pack failure detection apparatus characterized by comprising: The system comprises: 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, the one or more programs comprising instructions which, when executed by the processor, cause the processor to perform the method of any one of claims 1-4.

8. A computer-readable storage medium, characterized in that, The computer readable storage medium stores instructions, when the instructions run on the terminal device, cause the terminal device to perform the method of any one of claims 1-4.

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