Battery cell internal short circuit detection method, device, system, equipment and server

Abstract

The invention discloses a method, a device, a system, equipment and a server for detecting short circuit in a battery cell, and relates to the technical field of batteries. The method comprises the following steps: acquiring internal short-circuit resistance data of a to-be-tested cell; based on reference data, performing normalization processing on the internal short circuit resistance data of the to-be-detected battery cell to obtain normalized data of the to-be-detected battery cell, the reference data including the internal short circuit resistance data of a reference battery cell, and the reference battery cell and the to-be-detected battery cell being in the same working condition; and according to the normalized data, detecting whether the internal short circuit occurs in the to-be-detected battery cell. According to the cell internal short circuit detection method, the internal short circuit resistance data of the to-be-detected cell can be evaluated online by using the normalized data to detect whether the to-be-detected cell has internal short circuit or not, so that the abnormal internal short circuit cell is identified in real time, the normal use condition of the battery does not need to be interfered, and the abnormal internal short circuit cell can be identified in real time in more scenes.

Description

Technical Field

[0001] This application belongs to the technical field of batteries, and particularly relates to a method, device, system, equipment, and server for detecting internal short circuits in battery cells. Background Art

[0002] As batteries are widely used in new energy vehicles, battery safety issues, as a pain point in the industry, have increasingly attracted people's attention. Since internal short circuits in battery cells are closely related to battery safety and are one of the important causes of battery thermal runaway problems. Therefore, it is necessary to timely identify and warn whether the battery cells have internal short circuits to avoid serious safety accidents. Summary of the Invention

[0003] In view of the above problems, this application provides a method, device, system, equipment, and server for detecting internal short circuits in battery cells to provide a detection mechanism for internal short circuits in battery cells.

[0004] In a first aspect, this application provides a method for detecting internal short circuits in battery cells, including:

[0005] Obtaining internal short circuit resistance data of the battery cell to be tested;

[0006] Based on reference data, performing normalization processing on the internal short circuit resistance data of the battery cell to be tested to obtain the normalized data of the battery cell to be tested, where the reference data includes the internal short circuit resistance data of the reference battery cell, and the reference battery cell and the battery cell to be tested are in the same working condition;

[0007] According to the normalized data, detecting whether the battery cell to be tested has an internal short circuit.

[0008] In the technical solution of the embodiments of this application, based on reference data, normalization processing is performed on the internal short circuit resistance data of the battery cell to be tested to obtain the normalized data of the battery cell to be tested, so as to use the normalized data to determine whether the battery cell to be tested has an internal short circuit. The above method for detecting internal short circuits in battery cells can online use the normalized data to evaluate the internal short circuit resistance data of the battery cell to be tested to detect whether the battery cell to be tested has an internal short circuit, so as to real-time identify battery cells with internal short circuit abnormalities, without interfering with the normal use conditions of the battery, and can real-time identify battery cells with internal short circuit abnormalities in more scenarios.

[0009] In some embodiments, after detecting whether the battery cell to be tested has an internal short circuit according to the normalized data, the method further includes:

[0010] According to the detection result of whether the battery cell to be tested has an internal short circuit, detecting whether the battery to which the battery cell to be tested belongs is abnormal.

[0011] In this embodiment, it is possible to detect whether the battery to which the battery cell to be tested belongs is abnormal by detecting whether the battery cell to be tested has an internal short circuit.

[0012] In some embodiments, the method further includes:

[0013] Determining a reference cell based on the current operating condition of the cell to be tested;

[0014] Obtaining the internal short - circuit resistance data of the reference cell to obtain reference data.

[0015] In this embodiment, by determining a reference cell in the same operating condition, reference data can be obtained.

[0016] In some embodiments, determining a reference cell based on the current operating condition of the cell to be tested includes:

[0017] Based on the operating condition parameters of the battery to which the cell to be tested belongs, determining at least one cell included in the target battery as the reference cell, where the operating condition parameters of the target battery are the same as those of the battery to which the cell to be tested belongs, and the operating condition parameters include at least one of state of charge, temperature, current, and humidity.

[0018] In this embodiment, by using the operating condition parameters of the battery to which the cell to be tested belongs and the target battery to determine a reference cell in the same operating condition, it has the advantage of simple operating condition identification.

[0019] In some embodiments, based on the reference data, normalizing the internal short - circuit resistance data to obtain the normalized data of the cell to be tested, which is:

[0020] Based on the reference data, solving the z - score or entropy of the internal short - circuit resistance data of the cell to be tested to obtain the normalized data of the cell to be tested.

[0021] In this embodiment, the normalized data such as z - score or entropy can be used to detect and determine whether the cell to be tested has an internal short - circuit.

[0022] In some embodiments, detecting whether the cell to be tested has an internal short - circuit according to the normalized data includes:

[0023] Comparing the size of the normalized data with the corresponding threshold, and judging whether the cell to be tested has an internal short - circuit according to the comparison result.

[0024] In this embodiment, by comparing the size of the normalized data such as z - score or entropy with the corresponding threshold, it can be quickly and accurately judged whether the cell to be tested has an internal short - circuit.

[0025] In some embodiments, the normalized data is a negative z - score;

[0026] Comparing the size of the normalized data with the corresponding threshold, and judging whether the cell to be tested has an internal short - circuit according to the comparison result includes:

[0027] When the z-score of the battery cell under test is less than or equal to the first threshold, it is determined that the battery cell under test has an internal short circuit; otherwise, it is determined that the battery cell under test does not have an internal short circuit; or,

[0028] When the duration for which the z-score of the battery cell under test is less than or equal to the second threshold is greater than or equal to the first duration, it is determined that the battery cell under test has an internal short circuit; otherwise, it is determined that the battery cell under test does not have an internal short circuit, and the second threshold is greater than or equal to the first threshold.

[0029] In this embodiment, by setting the first threshold and / or the second threshold, the z-score can be used to quickly and accurately detect whether the battery cell under test has an internal short circuit.

[0030] In some embodiments, the normalized data is entropy or a z-score that does not take negative values;

[0031] Comparing the size between the normalized data and the corresponding threshold, and determining whether the battery cell under test has an internal short circuit according to the comparison result, includes:

[0032] When the normalized data of the battery cell under test is greater than or equal to the third threshold, it is determined that the battery cell under test has an internal short circuit; otherwise, it is determined that the battery cell under test does not have an internal short circuit; or,

[0033] When the duration for which the normalized data of the battery cell under test is greater than or equal to the fourth threshold is greater than or equal to the second duration, it is determined that the battery cell under test has an internal short circuit; otherwise, it is determined that the battery cell under test does not have an internal short circuit, and the third threshold is greater than or equal to the fourth threshold.

[0034] In this embodiment, by setting the third threshold and / or the fourth threshold, the z-score or entropy can be used to quickly and accurately detect whether the battery cell under test has an internal short circuit.

[0035] In some embodiments, based on reference data, normalizing the internal short circuit resistance data of the battery cell under test to obtain the normalized data of the battery cell under test, includes:

[0036] Performing outlier statistics on the reference data and the internal short circuit resistance data of the battery cell under test to obtain the normalized data of the battery cell under test.

[0037] In this embodiment, by finding outliers, it is possible to quickly and accurately determine whether the battery cell under test has an internal short circuit.

[0038] In some embodiments, performing outlier statistics on the reference data and the internal short circuit resistance data of the battery cell under test is:

[0039] Performing outlier statistics on the reference data and the internal short circuit resistance data of the battery cell under test in a statistical graph manner.

[0040] In this embodiment, performing outlier statistics in a statistical graph manner has the advantage of simple implementation.

[0041] In some embodiments, obtaining the internal short - circuit resistance data of the battery cell to be measured includes:

[0042] Obtaining the state data of the battery cell to be measured, where the state data includes the internal short - circuit voltage, the normal voltage, and the ohmic internal resistance;

[0043] According to the state data and the first functional relationship between the state data and the internal short - circuit resistance of the battery cell to be measured, determining the internal short - circuit resistance data of the battery cell to be measured.

[0044] In this embodiment, according to Kirchhoff's law, the internal short - circuit resistance data of the battery cell to be measured can be determined through the state data of the battery cell to be measured.

[0045] In some embodiments, the first functional relationship is determined based on the equivalent circuit model of a normal battery cell, the equivalent circuit model of a battery cell with an internal short - circuit anomaly, and Kirchhoff's law.

[0046] In this embodiment, the first functional relationship can be determined through different equivalent circuit models, so that the server can select corresponding data to calculate the internal short - circuit resistance data of the battery cell to be measured according to this first functional relationship.

[0047] In some embodiments, the method for determining the internal short - circuit voltage includes:

[0048] Determining the external short - circuit port voltage of the battery cell to be measured as the internal short - circuit voltage.

[0049] In this embodiment, by determining the external short - circuit port voltage of the battery cell to be measured as the internal short - circuit voltage, the difficulty of implementing this detection method can be reduced.

[0050] In some embodiments, the method for determining the normal voltage includes:

[0051] Based on the equivalent circuit model of a normal battery cell, determining the normal voltage of the battery cell to be measured; or,

[0052] Based on the electrochemical model of a normal battery cell, determining the normal voltage of the battery cell to be measured; or,

[0053] Determining the normal voltage of the battery cell to be measured from the historical data of the battery cell to be measured, where the historical data includes the normal voltage of the battery cell to be measured.

[0054] In this embodiment, a method for determining the normal voltage of the battery cell to be measured is disclosed, which can reduce the difficulty of implementing this detection method.

[0055] In some embodiments, based on the equivalent circuit model of a normal battery cell, determining the normal voltage of the battery cell to be measured includes:

[0056] Determine the open-circuit voltage according to the state of charge of the battery cell to be measured and the second functional relationship between the state of charge and the open-circuit voltage of the battery cell.

[0057] Determine the normal voltage according to the ohmic internal resistance, open-circuit voltage and current of the battery cell to be measured.

[0058] In this embodiment, a method for determining the normal voltage of a battery cell to be measured is disclosed, which can reduce the difficulty of implementing this detection method.

[0059] In some embodiments, the method for determining the ohmic internal resistance of a battery cell to be measured includes:

[0060] Obtain the state of charge and temperature of the battery cell to be measured;

[0061] Determine the ohmic internal resistance according to the state of charge and temperature of the battery cell to be measured, and the third functional relationship between the state of charge, temperature and ohmic internal resistance.

[0062] In this embodiment, a method for determining the ohmic internal resistance of a battery cell to be measured is disclosed, which can reduce the difficulty of implementing this detection method.

[0063] In some embodiments, after detecting whether the battery cell to be measured has an internal short circuit according to the normalized data, the method further includes:

[0064] In the case where the detection result is that the battery cell to be measured has an internal short circuit, control the battery cell to stop working.

[0065] In this embodiment, by controlling the battery cell with an internal short circuit to stop working, the risk of thermal runaway of the battery can be reduced, and the impact on the normal operation of other battery cells in the battery can be reduced.

[0066] In a second aspect, the present application provides a device for detecting internal short circuit of a battery cell, including a module for executing the method in any of the above embodiments.

[0067] In a third aspect, the present application provides a battery management system, including: a memory, a processor, and a program stored on the memory and executable on the processor. When the processor executes the program, the method in any of the above embodiments is implemented.

[0068] In a fourth aspect, the present application provides an electrical device, including a battery cell to be measured and the battery management system provided in the third aspect above.

[0069] In a fifth aspect, the present application provides an energy storage device, including a battery cell to be measured and the battery management system provided in the third aspect above.

[0070] Sixth aspect, the present application provides a server, including: a memory, a processor, and a program stored on the memory and executable on the processor. When the processor executes the program, the method in any of the above embodiments is implemented.

[0071] Seventh aspect, the present application provides a computer-readable storage medium. The computer-readable storage medium stores a program, and when the program is executed by a processor, the method in any of the above embodiments is implemented.

[0072] The above description is only an overview of the technical solutions of the present application. In order to be able to understand the technical means of the present application more clearly, it can be implemented according to the content of the specification. And in order to make the above and other purposes, features and advantages of the present application more obvious and understandable, the following specifically illustrates the specific embodiments of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0073] By reading the detailed description of the preferred embodiments below, various other advantages and benefits will become clear to those of ordinary skill in the art. The drawings are only for the purpose of showing the preferred embodiments and are not considered to be a limitation of the present application. Moreover, in all the drawings, the same reference numerals are used to represent the same components.

[0074] Figure 1a It is a schematic structural diagram of a vehicle in some embodiments of the present application;

[0075] Figure 1b It is an application schematic diagram of the method for detecting internal short circuit in a battery cell in some embodiments of the present application;

[0076] Figure 2 It is a schematic flow diagram of a method for detecting internal short circuit in a battery cell provided by an embodiment of the present application;

[0077] Figure 3 It is another schematic flow diagram of a method for detecting internal short circuit in a battery cell provided by an embodiment of the present application;

[0078] Figure 4 It is another schematic flow diagram of a method for detecting internal short circuit in a battery cell provided by an embodiment of the present application;

[0079] Figure 5 It is a schematic structural diagram of an equivalent circuit model of a normal battery cell provided by an embodiment of the present application;

[0080] Figure 6 It is a schematic structural diagram of an equivalent circuit model of a battery cell with internal short circuit abnormality provided by an embodiment of the present application;

[0081] Figure 7 It is a curve graph of open circuit voltage and state of charge provided by an embodiment of the present application;

[0082] Figure 8Internal short-circuit resistance data of a single battery cell provided by an embodiment of this application;

[0083] Figure 9 Z-scores of multiple battery cells provided by an embodiment of this application at different times;

[0084] Figure 10 Schematic structural diagram of a server provided by an embodiment of this application. Detailed implementation manners

[0085] The embodiments of the technical solution of this application will be described in detail below with reference to the accompanying drawings. The following embodiments are only used to illustrate the technical solution of this application more clearly, so they are only examples and cannot be used to limit the protection scope of this application.

[0086] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above accompanying drawings are intended to cover non-exclusive inclusion.

[0087] In the description of the embodiments of this application, technical terms such as "first" and "second" are only used to distinguish different objects and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity, specific order or primary-secondary relationship of the indicated technical features. In the description of the embodiments of this application, "a plurality of" means more than two unless otherwise specifically defined.

[0088] Referring to "embodiments" herein means that the specific features, structures or characteristics described in connection with the embodiments may be included in at least one embodiment of this application. The phrase appears in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art explicitly and implicitly understand that the embodiments described herein may be combined with other embodiments.

[0089] In the description of the embodiments of this application, the term "and / or" is only a description of the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B may represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this article generally represents an "or" relationship between the associated objects before and after.

[0090] In the embodiments of this application, the battery includes at least one battery cell. When the battery includes a plurality of battery cells, the plurality of battery cells can be combined in series, in parallel, or in series-parallel.

[0091] In the embodiments of the present application, a battery can be regarded as a device including at least one battery cell, such as a battery cell, a battery module, a battery pack, or a battery stack.

[0092] Internal short circuit in a battery cell mainly refers to a short circuit caused by physical contact inside the battery cell. For example, internal short circuit is caused by various reasons such as introduction of impurities due to manufacturing defects, dendrite formation due to internal lithium deposition, and collapse and decomposition of the separator. Since the path forming the above internal short circuit has a certain resistance, the short circuit current will not be very large. However, if the internal short circuit is not detected in time, there may be a thermal runaway accident such as a sudden increase in battery temperature, smoking, fire, or even explosion due to the internal short circuit, seriously affecting the battery safety and battery service life.

[0093] Therefore, the related art provides the following methods for detecting internal short circuit in a battery cell:

[0094] The first method for detecting internal short circuit in a battery cell includes: using the current conversion process from the pre-charge stage to the large-current charge stage during the charging of an electric vehicle, based on the collected voltage and current information, establishing an equivalent circuit model for the internal short circuit fault of the battery cell (such as a battery cell) with abnormal voltage during the small-current pre-charge stage, and using the extended Kalman filter and the least squares method with a forgetting factor to jointly estimate the SOC (State of Charge) and the internal short circuit resistance value of the battery, so as to judge whether there is an internal short circuit fault in the battery cell, and further realize the early diagnosis of the internal short circuit fault in the battery. However, this method requires the cooperation of the battery charging strategy, and there is no pre-charge process during normal charge and discharge, and the discharge process cannot be pre-charged either. Therefore, it will interfere with the battery under normal use scenarios, resulting in limited use scenarios.

[0095] The second method for detecting internal short circuit in a battery cell includes: at two different times, respectively obtaining the measured values of the battery terminal voltage, denoted as the first terminal voltage measured value and the second terminal voltage measured value; respectively obtaining the open-circuit voltage expressions corresponding to the times, denoted as the first open-circuit voltage expression and the second open-circuit voltage expression, and then calculating the resistance value of the equivalent short circuit; based on the resistance value, detecting whether the battery has an internal short circuit fault. However, this method requires finding the open-circuit state working condition, but most of the data generated during the service of the battery are charge and discharge data. Therefore, the use scenarios of this detection method are also limited.

[0096] In summary, the methods for detecting internal short circuit in a battery cell provided by the related art usually require the cooperation of specific charge and discharge strategies or are applied in specific scenarios, resulting in limited use scenarios for this detection method.

[0097] In view of this, an embodiment of the present application provides a method for detecting internal short circuit of an electric core. First, obtain the internal short circuit resistance data of the electric core to be tested. Secondly, based on the reference data, normalize the internal short circuit resistance data of the electric core to be tested to obtain the normalized data of the electric core to be tested. Among them, the reference data includes the internal short circuit resistance data of the reference electric core, and the reference electric core and the electric core to be tested are in the same working condition. The purpose of normalization is to limit the internal short circuit resistance data of the electric core to be tested within a certain range, so as to eliminate the adverse effects caused by singular sample data, so that the normalized data can be used to detect whether the electric core to be tested has an internal short circuit. Since the normalized data is used to detect whether the electric core to be tested has an internal short circuit, the internal short circuit resistance data of the electric core to be tested can be evaluated online using the normalized data to detect whether the electric core to be tested has an internal short circuit, so as to identify the electric core with internal short circuit abnormality in real time, without interfering with the normal use condition of the battery, and the electric core with internal short circuit abnormality can be identified in real time in more scenarios.

[0098] The battery in the embodiment of the present application can be a secondary battery. The battery in the embodiment of the present application can be used in an electrical device using the battery as a power source or various energy storage devices using the battery as an energy storage element. The electrical device can be, but is not limited to, a mobile phone, a tablet computer, a laptop computer, an electric toy, an electric tool, a battery car, an electric vehicle, a ship, a spacecraft, and the like. Among them, the electric toy can include fixed or mobile electric toys, such as game consoles, electric vehicle toys, electric ship toys, and electric aircraft toys. The spacecraft can include airplanes, rockets, space shuttles, and spaceships. The energy storage device can be, but is not limited to, various energy storage valve systems. For example, the energy storage valve system includes, but is not limited to, a high-voltage direct-connected energy storage valve system.

[0099] For the convenience of description, the scenario example of the embodiment of the present application is described by taking an electrical device as a vehicle as an example.

[0100] Please refer to Figure 1a , Figure 1aSchematic diagram of the structure of vehicle 1000 provided for this scenario example. Vehicle 1000 can be a new energy vehicle, and the new energy vehicle can be a pure electric vehicle, a hybrid vehicle, an extended-range vehicle, etc. Inside vehicle 1000, there is a battery 100, and the battery 100 includes at least one battery cell. The battery 100 can be arranged at the bottom, the head or the tail of vehicle 1000. The battery 100 can be used for power supply of vehicle 1000. For example, the battery 100 can be used as the operating power source of vehicle 1000. Vehicle 1000 can also include a controller 200 and a motor 300. The controller 200 is used to control the battery 100 to supply power to the motor 300, for example, for the working power requirements during the start, navigation and driving of vehicle 1000. In this scenario example, the battery 100 can not only be used as the operating power source of vehicle 1000, but also be used as the driving power source of vehicle 1000 to provide driving power for vehicle 1000.

[0101] Please refer to Figure 1b , Figure 1b Application schematic diagram of the internal short circuit detection method for battery cells provided in this scenario example. This internal short circuit detection method for battery cells can be applied to Figure 1b the battery management system (BMS) in vehicle 1000 in Figure 1b or can be applied to the server 120 or the mobile terminal 130 in

[0102] In this scenario example, the application of the internal short circuit detection method for battery cells to the server 120 is taken as an example for illustration. Specifically, a variety of sensors are installed on vehicle 1000 to collect data of the battery 100, such as at least one of current, voltage, temperature, state of charge (SOC). Vehicle 1000 sends the data of the battery 100 collected by at least one sensor to the server 120 through a communication module. The server 120 determines the internal short circuit resistance data of the battery cell to be tested according to the data of the battery 100. Then, the server 120 normalizes the internal short circuit resistance data of the battery cell to be tested based on the reference data, and the reference data includes the internal short circuit resistance data of a reference battery cell under the same working conditions as the battery cell to be tested. Finally, the server 120 detects whether the battery cell to be tested has an internal short circuit according to the normalized data.

[0103] It should be noted that for the process of the BMS or the mobile terminal 130 to implement the method for detecting internal short circuit of the battery cell, reference can also be made to the specific process of the above-mentioned server 120 for implementing the method for detecting internal short circuit of the battery cell, which will not be elaborated here.

[0104] It can be understood that the server 120 can be connected to a display device, and the battery cell where the internal short circuit occurs is displayed through the connected display device.

[0105] In the above scenario example, the internal short circuit resistance data of the battery cell to be tested can be evaluated online using the normalized data to detect whether the internal short circuit occurs in the battery cell to be tested, so as to identify the battery cell with internal short circuit anomaly in real time, without interfering with the normal use conditions of the battery, and the battery cell with internal short circuit anomaly can be identified and warned in real time in more scenarios.

[0106] To illustrate the technical solution of the present application, the following will be described through specific embodiments.

[0107] In the following embodiments, taking the server as the execution subject as an example, a method for detecting internal short circuit of a battery cell provided by the embodiments of the present application is described.

[0108] Please refer to Figure 2 , some embodiments of the present application provide a method for detecting internal short circuit of a battery cell, including the following steps:

[0109] S110. The server obtains the internal short circuit resistance data of the battery cell to be tested.

[0110] It should be noted that although the internal short circuit resistance of the battery cell cannot be directly measured, the internal short circuit resistance data of the battery cell can be determined through data such as current and voltage during the use of the battery cell, so as to obtain the internal short circuit resistance data of the battery cell to be tested.

[0111] Therefore, as an example, data such as current and voltage during the use of the battery cell can be stored in the server. For example, the BMS of the vehicle can upload the above current, voltage and other data to the server. Then the server can call the above stored data and calculate the internal short circuit resistance data of the battery cell based on this, so as to obtain the internal short circuit resistance data of the battery cell to be tested. For example, the internal short circuit resistance data generated in real time of the battery cell to be tested, and / or the internal short circuit resistance data of the battery cell to be tested in the past period of time can be obtained.

[0112] As another example, the BMS in the vehicle can also determine the internal short-circuit resistance data of the cell to be tested based on the acquired data such as the current and voltage of the cell, and then store or send these internal short-circuit resistance data to the server. For example, after the BMS in the vehicle determines the internal short-circuit resistance data of the cell to be tested, it can be sent to the server periodically or regularly. It can be understood that the internal short-circuit resistance data of the cell to be tested can carry tags reflecting time.

[0113] It should be noted that the calculated internal short-circuit resistance data can be expressed as the resistance at a certain moment or as the resistance during a certain time period, and the embodiments of the present application do not limit this.

[0114] S120. The server normalizes the internal short-circuit resistance data of the cell to be tested based on the reference data to obtain the normalized data of the cell to be tested.

[0115] Among them, the reference data includes the internal short-circuit resistance data of the reference cell, and the reference cell and the cell to be tested are in the same working condition.

[0116] Since the internal short-circuit mechanism of the cell is different under different working conditions and it is difficult to unify and quantify, and the external characteristics such as the voltage of the cell are not obvious when the internal short-circuit occurs and it is difficult to identify. Therefore, in the embodiments of the present application, the internal short-circuit resistance data of the cell to be tested is normalized based on the reference data to obtain the normalized data of the cell to be tested, which can unify and quantify the internal short-circuit resistance data of the cell to be tested under any working condition.

[0117] In the embodiments of the present application, the working condition of the cell is determined by the working condition of the battery to which it belongs. For example, different cells in the same battery can be considered to be in the same working condition. Another example is that if the working conditions of two batteries are the same, it can be considered that any cell in one battery and any cell in the other battery are in the same working condition.

[0118] It should also be noted that the above cell to be tested and the reference cell can be the same cell or different cells.

[0119] As an example, in the case where the cell to be tested and the reference cell are the same cell, the internal short-circuit resistance data of the cell to be tested and the internal short-circuit resistance data of the reference cell are essentially the internal short-circuit resistance data of the cell to be tested at different times but in the same working condition. For example, the internal short-circuit resistance data of the cell to be tested refers to the internal short-circuit resistance data of the cell to be tested at the first time and in the first working condition; the internal short-circuit resistance data of the reference cell refers to the internal short-circuit resistance data of the cell to be tested at the second time and in the first working condition.

[0120] As an example, when the battery cell under test and the reference battery cell are different battery cells, the batteries to which the battery cell under test belongs and the batteries to which the reference battery cell belongs can be the same or different, but the operating conditions of the two batteries are the same. For example, the internal short-circuit resistance data of the battery cell under test and the internal short-circuit resistance data of the reference battery cell are respectively the internal short-circuit resistance data of different battery cells in the same battery; or the internal short-circuit resistance data of battery cells in different batteries respectively.

[0121] In the embodiments of the present application, the operating condition of the battery refers to the working state of the battery under different usage environments. For example, the factors affecting the operating condition of the battery include but are not limited to: the state of charge (SOC) of the battery, temperature, current, and humidity.

[0122] It should be noted that the purpose of normalization is to limit the internal short-circuit resistance data of the battery cell under test within a certain range, so as to eliminate the adverse effects caused by singular sample data, so that the normalized data can be used to detect whether the battery cell under test has an internal short circuit.

[0123] As an example, the normalized data is used to reflect the discrete situation of the internal short-circuit resistance data of the battery cell under test and the reference data.

[0124] As an example, the normalized data used to reflect the discrete situation of the internal short-circuit resistance data of the battery cell under test and the reference data includes but is not limited to data such as standard deviation, z-score, entropy, and whether there are outliers.

[0125] S130. The server detects whether the battery cell under test has an internal short circuit according to the normalized data.

[0126] For example, the discrete situation of the internal short-circuit resistance data of the battery cell under test can be determined through the normalized data to detect whether the battery cell under test has an internal short circuit.

[0127] For example, if the degree of discreteness of the normalized data is large, it is determined that the battery cell under test has an internal short circuit. If the degree of discreteness of the normalized data is small, it is determined that the battery cell under test has not had an internal short circuit.

[0128] In the above battery cell internal short-circuit detection method, the internal short-circuit mechanisms of battery cells under the same operating conditions can be considered the same (or approximately the same), so that the internal short-circuit resistance data of the battery cell under test under any operating condition can be uniformly quantified through normalization processing. Such a setting can be used to evaluate the internal short-circuit resistance data of the battery cell under test online using the normalized data to detect whether the battery cell under test has an internal short circuit, so as to identify abnormal battery cells with internal short circuits in real time, without interfering with the normal operating conditions of the battery, and abnormal battery cells with internal short circuits can be identified in real time in more scenarios.

[0129] In some embodiments of the present application, after step S130, the above-mentioned internal short-circuit detection method for the battery cell further includes the following steps:

[0130] S210. The server detects whether the battery to which the battery cell to be tested belongs is abnormal according to the detection result of whether the battery cell to be tested has an internal short circuit.

[0131] For example, when the detection result is that the battery cell to be tested has an internal short circuit, it is determined that the battery to which the battery cell to be tested belongs is abnormal, that is, the battery has an internal short circuit. When the detection result is that the battery cell to be tested does not have an internal short circuit, it is determined that the battery to which the battery cell to be tested belongs is normal, that is, the battery does not have an internal short circuit.

[0132] The above-mentioned internal short-circuit detection method for the battery cell can detect whether the battery to which the battery cell to be tested belongs is abnormal by detecting whether the battery cell to be tested has an internal short circuit.

[0133] In some embodiments of the present application, the internal short-circuit detection method for the battery cell further includes:

[0134] S310. Determine a reference battery cell based on the current working condition of the battery cell to be tested.

[0135] Since the reference data includes the internal short-circuit resistance data of the reference battery cell under the same working condition as the battery cell to be tested, a reference battery cell under the same working condition as the battery cell to be tested can be determined first to determine the reference data. That is, a reference battery cell can be determined first based on the current working condition of the battery cell to be tested.

[0136] S320. Obtain the internal short-circuit resistance data of the reference battery cell to obtain reference data.

[0137] In the case of determining the reference battery cell, the internal short-circuit resistance data of the reference battery cell can be obtained, thereby obtaining reference data.

[0138] For example, when the reference battery cell and the battery cell to be tested are the same battery cell, the internal short-circuit resistance data of the battery cell to be tested and the internal short-circuit resistance data of the reference battery cell are essentially the internal short-circuit resistance data of the battery cell to be tested under the same working condition at different times.

[0139] For example, when the reference battery cell and the battery cell to be tested are different battery cells, if the reference battery cell and the battery cell to be tested belong to the same battery, it is determined that the reference battery cell and the battery cell to be tested are in the same working condition. For example, the internal short-circuit resistance data of the battery cell to be tested is the internal short-circuit resistance data of the battery cell to be tested under the first working condition, and the internal short-circuit resistance data of the reference battery cell is the internal short-circuit resistance data of the reference battery cell under the first working condition.

[0140] For example, when the reference battery cell and the battery cell to be measured are different battery cells, if the reference battery cell and the battery cell to be measured belong to different batteries respectively, but the different batteries are in the same working condition, it is determined that the reference battery cell and the battery cell to be measured are in the same working condition. For example, the battery cell to be measured belongs to the first battery, and the internal short-circuit resistance data of the battery cell to be measured is the internal short-circuit resistance data of the first battery under the first working condition. The reference battery cell belongs to the second battery, and the internal short-circuit resistance data of the reference battery cell is the internal short-circuit resistance data of the second battery under the first working condition. The first battery and the second battery are different batteries.

[0141] The above method for detecting internal short circuit of battery cells determines a reference battery cell in the same working condition as the battery cell to be measured in order to determine reference data.

[0142] In some embodiments, based on the current working condition of the battery cell to be measured, determining a reference battery cell includes the following steps:

[0143] S311. Based on the working condition parameters of the battery to which the battery cell to be measured belongs, determine at least one battery cell included in the target battery as the reference battery cell, where the working condition parameters of the target battery are the same as those of the battery to which the battery cell to be measured belongs, and the working condition parameters include at least one of state of charge, temperature, current, and humidity.

[0144] It should be noted that the above-mentioned "same" means that the working condition parameters between the battery to which the battery cell to be measured belongs and the target battery to which the reference battery cell belongs are exactly equal, or the difference between them is within the allowable range.

[0145] For example, when the working condition parameters include the state of charge, the same working condition parameters can be understood as that the state of charge of the battery to which the battery cell to be measured belongs and the target battery to which the reference battery cell belongs are the same. For example, the state of charge of the battery to which the battery cell to be measured belongs and the target battery to which the reference battery cell belongs are exactly equal, or the difference is within 1%.

[0146] For example, when the working condition parameters include current, the same working condition parameters can be understood as that the current of the battery to which the battery cell to be measured belongs and the target battery to which the reference battery cell belongs are the same. For example, the current of the battery to which the battery cell to be measured belongs and the target battery to which the reference battery cell belongs are exactly equal, or the difference is within 10 mA.

[0147] For example, when the working condition parameters include the state of charge, temperature, current, and humidity, the same working condition parameters can be understood as that the state of charge, temperature, current, and humidity of the battery to which the battery cell to be measured belongs and the target battery to which the reference battery cell belongs are the same. For example, the state of charge, temperature, current, and humidity of the battery to which the battery cell to be measured belongs and the target battery to which the reference battery cell belongs are exactly equal, or the difference in the state of charge is within 1%, the difference in temperature is within 0.1 °C, the difference in current is within 10 mA, and the difference in humidity is within 1%.

[0148] It should be understood that the battery to which the battery cell to be measured belongs and the target battery to which the reference battery cell belongs may be the same battery or different batteries, which will not be elaborated here.

[0149] In the above method for detecting internal short circuit of a battery cell, at least one battery cell in the same working condition as the battery cell to be measured is determined as the reference battery cell through the working condition parameters of the battery to which the battery cell to be measured belongs and the target battery to which the reference battery cell belongs, which has the advantage of simple working condition identification.

[0150] In some embodiments, since the working condition parameters of different batteries connected in series are approximately the same, the working conditions of different batteries connected in series can also be regarded as the same working condition, so as to determine the battery cells in the same working condition. For example, the battery to which the battery cell to be measured belongs and the target battery to which the reference battery cell belongs are different batteries, and the different batteries are connected in series and work together. At this time, the working conditions of these different batteries can be regarded as the same working condition, so as to determine that the battery cell to be measured and the reference battery cell are in the same working condition.

[0151] In the above method for detecting internal short circuit of a battery cell, by judging whether the battery to which the battery cell to be measured belongs and the target battery to which the reference battery cell belongs are in a series relationship, it is determined whether the battery cell to be measured and the reference battery cell are in the same working condition, which has the advantage of simple working condition identification.

[0152] Please refer to Figure 3 , in some embodiments of the present application, the above step S120 may be:

[0153] S410. Based on the reference data, solve the z-score or entropy of the internal short-circuit resistance data of the battery cell to be measured to obtain the normalized data of the battery cell to be measured.

[0154] For example, the z-score, also called the standard score, is a process of subtracting a number from the average and then dividing by the standard deviation. Therefore, as an example, the internal short-circuit resistance data of the battery cell to be measured corresponds to a z-score. The z-score can be used to represent the degree of dispersion between the internal short-circuit resistance data of the battery cell to be measured and the reference data.

[0155] For example, the standard deviation, which refers to the arithmetic square root of the arithmetic mean of the squared deviations from the mean (i.e., the variance), is denoted by σ. The standard deviation is also known as the standard deviation or the experimental standard deviation, and is most commonly used in probability statistics to measure the degree of dispersion of a set of numerical values. In the embodiments of the present application, the standard deviation can be used to represent the degree of dispersion between the internal short-circuit resistance data of the battery cell to be measured and the reference data.

[0156] Correspondingly, in the field of mathematical statistics, entropy can also be used to reflect the degree of dispersion of a set of numerical values.

[0157] Therefore, it is possible to detect and judge whether the battery cell to be measured has an internal short circuit through the z-score or entropy of the internal short-circuit resistance data of the battery cell to be measured.

[0158] As an example, the above step S130 may include the following steps:

[0159] S510. Compare the normalized data with the corresponding threshold, and determine whether the battery cell to be tested has an internal short circuit according to the comparison result.

[0160] Since the normalized data can eliminate the adverse effects caused by singular sample data, it is possible to quickly and accurately determine whether the battery cell to be tested has an internal short circuit through the comparison result between the normalized data and the corresponding threshold.

[0161] In the above method for detecting internal short circuit of a battery cell, by comparing the normalized data such as z-score or entropy with the corresponding threshold, it is possible to quickly and accurately determine whether the battery cell to be tested has an internal short circuit.

[0162] In some embodiments of the present application, the normalized data is a z-score and is negative. The above step S510 includes the following steps:

[0163] S511. When the z-score of the battery cell to be tested is less than or equal to the first threshold, it is determined that the battery cell to be tested has an internal short circuit; otherwise, it is determined that the battery cell to be tested does not have an internal short circuit; or,

[0164] S512. When the duration for which the z-score of the battery cell to be tested is less than or equal to the second threshold is greater than or equal to the first duration, it is determined that the battery cell to be tested has an internal short circuit; otherwise, it is determined that the battery cell to be tested does not have an internal short circuit, and the second threshold is greater than or equal to the first threshold.

[0165] For example, in step S511, when the z-score of the battery cell to be tested is less than or equal to the first threshold, it is determined that the battery cell to be tested has an internal short circuit, and it is determined that the battery to which the battery cell to be tested belongs is abnormal. Otherwise, it is determined that none of the battery cells to be tested have an internal short circuit, and it is determined that the battery to which the battery cell to be tested belongs is normal.

[0166] For example, in step S512, when the duration for which the z-score of the battery cell to be tested is less than or equal to the second threshold is greater than or equal to the first duration, it is determined that the battery cell to be tested has an internal short circuit, and it is determined that the battery to which the battery cell to be tested belongs is abnormal. Otherwise, it is determined that none of the battery cells to be tested have an internal short circuit, and it is determined that the battery to which the battery cell to be tested belongs is normal.

[0167] In an embodiment of the present application, as an example, the first threshold is -6, the second threshold is -4, and the first duration is 10 minutes.

[0168] In the above method for detecting internal short circuit of a battery cell, by setting the first threshold and / or the second threshold, it is possible to quickly and accurately determine whether the battery cell to be tested has an internal short circuit by using the z-score.

[0169] In some embodiments of the present application, the normalized data is entropy or a z-score that is not negative.

[0170] The above step S510 includes the following steps:

[0171] S513. When the z-score or entropy of the battery cell under test is greater than or equal to a third threshold, it is determined that an internal short circuit has occurred in the battery cell under test; otherwise, it is determined that no internal short circuit has occurred in the battery cell under test; or,

[0172] S514. When the duration for which the z-score or entropy of the battery cell under test is greater than or equal to a fourth threshold is greater than or equal to a second duration, it is determined that an internal short circuit has occurred in the battery cell under test; otherwise, it is determined that no internal short circuit has occurred in the battery cell under test, and the third threshold is greater than or equal to the fourth threshold.

[0173] For example, in step S513, when the z-score or entropy of the battery cell under test is less than or equal to the third threshold, it is determined that an internal short circuit has occurred in the battery cell under test, and it is determined that the battery to which the battery cell under test belongs is abnormal. Otherwise, it is determined that no internal short circuit has occurred in any of the battery cells under test, and it is determined that the battery to which the battery cell under test belongs is normal.

[0174] For example, in step S514, when the duration for which the z-score or entropy of the battery cell under test is less than or equal to the fourth threshold is greater than or equal to the second duration, it is determined that an internal short circuit has occurred in the battery cell under test, and it is determined that the battery to which the battery cell under test belongs is abnormal. Otherwise, it is determined that no internal short circuit has occurred in any of the battery cells under test, and it is determined that the battery to which the battery cell under test belongs is normal.

[0175] In the embodiments of the present application, as an example, the absolute values of the first threshold and the third threshold may be equal or may not be equal; the absolute values of the second threshold and the fourth threshold may be equal or may not be equal; the first duration and the second duration may be equal or may not be equal. For example, when the normalized data is the z-score, the third threshold may be 6, the fourth threshold may be 4, and the second duration may also be 10 minutes.

[0176] In the above method for detecting internal short circuit of a battery cell, by setting the third threshold and / or the fourth threshold, it is possible to quickly and accurately determine whether an internal short circuit has occurred in the battery cell under test by using the z-score or entropy.

[0177] In some embodiments of the present application, in a set of data, according to the meanings of the standard deviation, z-score, and entropy, each data has a corresponding z-score and entropy. However, the standard deviation is a corresponding set of data used to reflect the overall degree of dispersion, rather than reflecting the dispersion of a single data, that is, a set of data corresponds to one standard deviation.

[0178] Therefore, when the standard deviation of the battery cell under test is less than or equal to the fifth threshold, it can be determined that there is a battery cell with internal short circuit in the battery cell under test and the reference battery cell; otherwise, it is determined that neither the battery cell under test nor the reference battery cell has an internal short circuit. Or, when the duration for which the standard deviation of the battery cell under test is less than or equal to the sixth threshold is greater than or equal to the third duration, it can be determined that there is a battery cell with internal short circuit in the battery cell under test and the reference battery cell; otherwise, it is determined that neither the battery cell under test nor the reference battery cell has an internal short circuit, and the sixth threshold is greater than or equal to the fifth threshold.

[0179] For example, when the standard deviation of the battery cell under test is less than or equal to the fifth threshold, it can be determined that there is a battery cell with internal short circuit in the battery cell under test and the reference battery cell, but it is impossible to determine which specific battery cell has an internal short circuit. In this case, when the battery cell under test and the reference battery cell belong to the same battery, it is also determined that the battery is abnormal; when the battery cell under test and the reference battery cell belong to different batteries, it is also determined that at least one of the different batteries is abnormal.

[0180] For example, when the duration for which the standard deviation of the battery cell under test is less than or equal to the sixth threshold is greater than or equal to the third duration, it can be determined that there is a battery cell with internal short circuit in the battery cell under test and the reference battery cell, but it is impossible to determine which specific battery cell has an internal short circuit. In this case, when the battery cell under test and the reference battery cell belong to the same battery, it is also determined that the battery is abnormal; when the battery cell under test and the reference battery cell belong to different batteries, it is also determined that at least one of the different batteries is abnormal.

[0181] Therefore, in some embodiments of the present application, a method for detecting internal short circuit of a battery is provided, which may include the following steps:

[0182] Obtain the internal short circuit resistance data of the battery cell under test and the reference data, where the reference data includes the internal short circuit resistance data of the reference battery cell, and the reference battery cell is under the same working condition as the battery cell under test;

[0183] Calculate the standard deviation of the internal short circuit resistance data of the battery cell under test and the internal short circuit resistance data of the reference battery cell;

[0184] According to the standard deviation, detect whether the battery to which the battery cell under test belongs and the battery to which the reference battery cell belongs have an internal short circuit.

[0185] For example, when the standard deviation is less than or equal to the fifth threshold, it can be determined that there is a battery cell with internal short circuit in the battery cell under test and the reference battery cell, but it is impossible to determine which specific battery cell has an internal short circuit. In this case, when the battery cell under test and the reference battery cell belong to the same battery, it is also determined that the battery is abnormal; when the battery cell under test and the reference battery cell belong to different batteries, it is also determined that at least one of the different batteries is abnormal.

[0186] For example, when the duration during which the standard deviation is less than or equal to the sixth threshold is greater than or equal to the third duration, it can be determined that there is a cell with an internal short circuit in the cell under test and the reference cell, but it is impossible to determine which specific cell has an internal short circuit. In this case, when the cell under test and the reference cell belong to the same battery, it is further determined that the battery is abnormal; when the cell under test and the reference cell belong to different batteries, it is further determined that at least one of the different batteries is abnormal.

[0187] In the above method for detecting internal short circuit of a battery, by setting the fifth threshold and / or the sixth threshold, it is possible to quickly and accurately determine whether there is a cell with an internal short circuit in the cell under test and the reference cell by using the standard deviation, and to determine whether the battery to which the cell under test belongs and the battery to which the reference cell belongs have an internal short circuit.

[0188] In some embodiments of the present application, the normalized data is an outlier statistical result, and the above step S120 may include the following steps:

[0189] S610. Perform outlier statistics on the reference data and the internal short circuit resistance data of the cell under test to obtain the normalized data of the cell under test.

[0190] For example, the outlier statistical result is the normalized data of the cell under test.

[0191] For example, outlier statistics can be performed on the reference data and the internal short circuit resistance data of the cell under test in some statistical graph forms to obtain the outlier statistical result. For example, the statistical result is whether there are outliers in the internal short circuit resistance data of the cell under test.

[0192] A statistical graph refers to an information graph used in the field of statistics to visualize quantitative data. In the embodiments of the present application, the statistical graph can intuitively reflect the differences in the internal short circuit resistance of the cells and the change trend of the internal short circuit resistance of the cells.

[0193] As an example, the statistical graph includes but is not limited to a scatter plot, a histogram, a probability plot, a residual plot, a box plot, a block plot, and a biplot.

[0194] Therefore, according to the outlier statistical result obtained in the above step S610, it can be determined whether there are outliers in the internal short circuit resistance data of the cell under test.

[0195] In the embodiments of the present application, the above step S130 may include the following steps:

[0196] S710. When the outlier statistical result indicates that there are outliers in the internal short circuit resistance data of the cell under test, it is determined that the cell under test has an internal short circuit; otherwise, it is determined that the cell under test does not have an internal short circuit.

[0197] For example, when the outlier statistical result indicates that there is an outlier in the internal short - circuit resistance data of the cell under test, it means that the internal short - circuit resistance data of the cell under test corresponding to this outlier is abnormal, that is, it is determined that the cell under test corresponding to this outlier has an internal short - circuit. When the outlier statistical result indicates that there is no outlier in the internal short - circuit resistance data of the cell under test, it is determined that the cell under test has not had an internal short - circuit.

[0198] The above - mentioned method for detecting the internal short - circuit of the cell can quickly and accurately determine whether the cell under test has an internal short - circuit by finding outliers.

[0199] Please refer to Figure 4 , in some embodiments of the present application, the above - mentioned step S110 includes the following steps:

[0200] S810. The server obtains the status data of the cell under test uploaded by the BMS. The status data includes the internal short - circuit voltage, the normal voltage, and the ohmic internal resistance.

[0201] As an example, the internal short - circuit voltage of the cell under test can be directly measured by measuring the external short - circuit port voltage of the cell under test. Therefore, the external short - circuit port voltage of the cell under test can be determined as the internal short - circuit voltage.

[0202] As an example, the normal voltage of the cell under test refers to the port voltage when the cell under test has no internal short - circuit. However, since it is not determined whether the cell under test has an internal short - circuit before detection, the normal voltage of the cell under test cannot be directly measured. In the embodiments of the present application, the normal voltage of the cell under test can be calculated by related technologies, or the normal voltage of the cell under test can be obtained from the historical data of the cell under test. For example, the historical data may include the normal voltage data calibrated when the cell under test leaves the factory, so this data can be used as the normal voltage in step S810.

[0203] As an example, since as the battery is used, data such as the current and voltage of the cell at different times can be uploaded to the server. Therefore, the server can calculate the ohmic internal resistance of the cell under test accordingly by related technologies. As another example, in other embodiments of the present application, other related technical means can also be used to evaluate and calculate the ohmic internal resistance of the cell under test, and then the server obtains the ohmic internal resistance of the cell under test obtained by this evaluation and calculation.

[0204] S820. The server determines the internal short - circuit resistance data of the cell under test according to the status data and the first functional relationship between the status data and the internal short - circuit resistance of the cell under test.

[0205] On the basis of determining the status data, the internal short - circuit resistance data of the cell under test can be determined according to the first functional relationship between the status data and the internal short - circuit resistance of the cell under test.

[0206] For example, based on the equivalent circuit model of the battery cell to be measured, the above first functional relationship can be determined.

[0207] As an example, the equivalent circuit model of a normal battery cell is as Figure 5 shown, and the equivalent circuit model of a battery cell with an internal short circuit anomaly is as Figure 6 shown. Among them, a normal battery cell refers to a battery cell without an internal short circuit, and a battery cell with an internal short circuit anomaly refers to a battery cell with an internal short circuit.

[0208] According to Kirchhoff's law, the following first functional relationship can be derived:

[0209]

[0210] Among them, R ISC is the internal short circuit resistance, U ISC is the internal short circuit voltage, U is the normal voltage, and R is the ohmic internal resistance.

[0211] Based on the above first functional relationship, on the basis of determining the internal short circuit voltage, the normal voltage, and the ohmic internal resistance, the internal short circuit resistance can be determined.

[0212] For the above method for detecting the internal short circuit of a battery cell, according to Kirchhoff's law, the internal short circuit resistance data of the battery cell to be measured can be determined through the state data of the battery cell to be measured.

[0213] In some embodiments of the present application, the first functional relationship is determined based on the equivalent circuit model of a normal battery cell, the equivalent circuit model of a battery cell with an internal short circuit anomaly, and Kirchhoff's law.

[0214] For example, the equivalent circuit model of a normal battery cell includes, but is not limited to, a first-order or second-order equivalent circuit model. It should be understood that the equivalent circuit model of a battery cell with an internal short circuit anomaly is obtained by adding an internal short circuit resistance R ISC to the equivalent circuit model of a normal battery cell. For example, as shown in Figure 5 and Figure 6 shown.

[0215] For the above method for detecting the internal short circuit of a battery cell, the first functional relationship can be determined through different equivalent circuit models, so that the server can select corresponding data to calculate the internal short circuit resistance data of the battery cell to be measured according to the first functional relationship.

[0216] In some embodiments of the present application, the method for determining the above internal short circuit voltage includes:

[0217] S811. The server determines the external short circuit port voltage of the battery cell to be measured uploaded by the BMS as the internal short circuit voltage.

[0218] For example, the external short - circuit port voltage of the battery cell to be measured can be directly measured by a sensor and uploaded to the server. The server uses this external short - circuit port voltage as the internal short - circuit voltage.

[0219] In the above - mentioned method for detecting internal short - circuit of a battery cell, by determining the external short - circuit port voltage of the battery cell to be measured as the internal short - circuit voltage, the difficulty of implementing this detection method can be reduced.

[0220] In some embodiments of the present application, the method for determining the above - mentioned normal voltage includes:

[0221] S812. The server determines the normal voltage of the battery cell to be measured based on the equivalent circuit model of a normal battery cell or the electrochemical model of a normal battery cell; or, the server determines the normal voltage of the battery cell to be measured from the historical data of the battery cell to be measured, where the historical data includes the normal voltage data of the battery cell to be measured.

[0222] For example, the normal voltage of the battery cell to be measured can be determined according to Figure 5 the equivalent circuit model of a normal battery cell as shown. Also, for example, in the historical data of the battery cell to be measured, there is included the previously determined normal voltage data or the normal voltage data calibrated at the time of leaving the factory of the battery cell to be measured, and then the normal voltage data in this data is used as the normal voltage in step S812.

[0223] The above - mentioned method for detecting internal short - circuit of a battery cell discloses a method for determining the normal voltage of the battery cell to be measured, which can reduce the difficulty of implementing this detection method.

[0224] In some embodiments of the present application, based on the equivalent circuit model of a normal battery cell, determining the normal voltage of the battery cell to be measured may include the following steps:

[0225] S8121. The server determines the open - circuit voltage according to the state of charge of the battery cell to be measured uploaded by the BMS and the second functional relationship between the state of charge and the open - circuit voltage of the battery cell to be measured.

[0226] In the related art, the functional relationship between the state of charge and the open - circuit voltage can be reflected by the second functional relationship. Therefore, after determining the state of charge of the battery cell to be measured, the open - circuit voltage can be determined through the second functional relationship.

[0227] As an example, in a laboratory environment, the second functional relationship can be determined in advance by means of interpolation or linear fitting. For example, the second functional relationship can be a specific formula or a table with a mapping relationship, so as to determine the open - circuit voltage by substituting into the formula or by the look - up table method.

[0228] S8122. The server determines the normal voltage according to the ohmic internal resistance, open - circuit voltage and current of the battery cell to be measured.

[0229] According to Kirchhoff's law, the sum of the product of the ohmic internal resistance and the current and the normal voltage is equal to the open-circuit voltage. Therefore, when determining the ohmic internal resistance, open-circuit voltage, and current of the cell under test, the normal voltage of the cell under test can be determined accordingly.

[0230] The above method for detecting internal short circuit of a cell discloses a method for determining the normal voltage of a cell under test, which can reduce the difficulty of implementing this detection method.

[0231] In some embodiments of the present application, the method for determining the ohmic internal resistance of a cell under test may include the following steps:

[0232] S813. The server obtains the state of charge and temperature of the cell under test uploaded by the BMS.

[0233] For example, the temperature can be directly measured by a sensor and uploaded to the server through the BMS. Again, for example, methods such as ampere-hour integration and Kalman filtering can be used to estimate the state of charge of the cell.

[0234] S814. The server determines the ohmic internal resistance according to the state of charge and temperature of the cell under test, and the third functional relationship between the state of charge, temperature, and ohmic internal resistance.

[0235] For example, since the ohmic internal resistance of a battery is related to temperature and state of charge, data on the ohmic internal resistance measured at different states of charge and temperatures in a laboratory can be used, and interpolation or multiple linear fitting can be performed to obtain the third functional relationship between the ohmic internal resistance, state of charge, and temperature. For example, the third functional relationship can be a specific formula or a table with a mapping relationship, so as to determine the ohmic internal resistance by substituting into the formula or by looking up the table.

[0236] Therefore, according to the state of charge, temperature, and the third functional relationship of the cell under test, the ohmic internal resistance of the cell under test can be determined.

[0237] The above method for detecting internal short circuit of a cell discloses a method for determining the ohmic internal resistance of a cell under test, which can reduce the difficulty of implementing this detection method.

[0238] In some embodiments of the present application, after step S130, the method for detecting internal short circuit of a cell may further include the following steps:

[0239] S910. In the case where the detection result is that the cell under test has an internal short circuit, the server controls the cell under test to stop working.

[0240] For example, the server can control the cell under test with an internal short circuit to stop working by sending an instruction to the BMS.

[0241] The above method for detecting internal short circuit of the battery cell can stop the battery cell under test with internal short circuit, so as to reduce the risk of thermal runaway of the battery and the impact on the normal operation of other battery cells in the battery.

[0242] In summary, in some embodiments of the present application, the method for detecting internal short circuit of the battery cell may include the following steps:

[0243] (1) The server obtains the status data of the battery cell under test uploaded by the BMS, such as voltage, current, state of charge, temperature, etc. As an optional implementation manner of this embodiment, the server also cleans these status data to remove invalid data. For example, the invalid data includes but is not limited to data beyond the preset range. For example, a voltage exceeding 5V is invalid data, and a state of charge beyond the range of 0-100% is invalid data.

[0244] (2) Interpolation (or multiple linear fitting) is performed using the ohmic internal resistance data at different states of charge and temperatures tested in the laboratory to obtain the third functional relationship between the ohmic internal resistance, temperature, and state of charge. Then, the ohmic internal resistance of the battery cell is calculated based on the temperature and state of charge of the battery cell under test.

[0245] Using the state of charge and open circuit voltage tested in the laboratory, interpolation is performed to obtain the second functional relationship between the state of charge and the open circuit voltage, and then the open circuit voltage is calculated according to the state of charge of the battery cell under test. For example, as Figure 7 shown, a relationship curve between the state of charge and the open circuit voltage is shown.

[0246] Based on the equivalent circuit model of a normal battery cell, the normal voltage of the battery cell under test is obtained based on the ohmic internal resistance, open circuit voltage, and current data. For example, as Figure 5 shown, U = E - I*R, where U is the normal voltage, E is the open circuit voltage, I is the current, and R is the ohmic internal resistance.

[0247] (3) According to the first functional relationship determined by the equivalent circuit model of the normal battery cell and the equivalent circuit model of the battery cell with internal short circuit abnormality, the internal short circuit resistance of the battery cell under test is determined, so as to obtain the internal short circuit resistance data of the battery cell under test. Among them, the first functional relationship is a relational expression between the internal short circuit voltage, normal voltage, ohmic internal resistance, and internal short circuit resistance. The derivation process is as follows:

[0248] According to Figure 5 the equivalent circuit model of the normal battery cell shown, it can be considered that its terminal voltage is: U = E - I*R.

[0249] According to Figure 6 the equivalent circuit model of the battery cell with internal short circuit abnormality shown, the following formula can be obtained: E - I R *R = I ISC *RISC , I R -I ISC = I.

[0250] Based on the above three equations, the following can be solved:

[0251] Then the following equations can be derived:

[0252] Finally, the calculation formula for the internal short-circuit resistance is derived:

[0253] According to the above calculation formula for the internal short-circuit resistance, the internal short-circuit resistance data of the battery cell to be measured can be calculated. For example, as Figure 8 shown, it is the internal short-circuit resistance data of a battery cell, where the vertical axis is the resistance value and the horizontal axis is the time.

[0254] (4) Based on the current working condition of the battery cell to be measured, determine a reference battery cell to determine reference data. And based on the reference data, normalize the internal short-circuit resistance data of the battery cell to be measured to obtain the normalized data of the battery cell to be measured. The reference data includes the internal short-circuit resistance data of the reference battery cell under the same working condition as the battery cell to be measured.

[0255] For example, the battery cell to be measured and the reference battery cell belong to the same battery, and the reference battery cell includes 4 battery cells. The battery cell to be measured and the reference battery cells total 5 battery cells.

[0256] As a first example:

[0257] For example, the internal short-circuit resistances of the 5 battery cells determined according to the above method are 7899.275466 ohms (Ω), 7907.174741 Ω, 1974.719138 Ω (corresponding to the battery cell to be measured), 7898.485538 Ω, and 7899.267566 Ω in sequence.

[0258] For example, the working condition parameters of the battery include the state of charge, temperature, and current, which are equal to 54%, 18 °C, and -15.2 amperes (A) respectively.

[0259] As a second example:

[0260] For example, the internal short-circuit resistances of the 5 battery cells determined according to the above method are 5743.417775 Ω, 5749.161193 Ω, 1435.781933 Ω (corresponding to the battery cell to be measured), 5742.843433 Ω, and 5743.412032 Ω in sequence.

[0261] For example, the working condition parameters of the battery include the state of charge, temperature, and current, which are equal to 54%, 18 °C, and -15.3 A respectively.

[0262] It should be noted that the data given in the first example and the second example are the data of the battery at different times respectively. Moreover, since the current in the operating conditions parameters differs by 0.1 A, the operating conditions of the battery in the first example and the second example are different.

[0263] (5) Normalize the internal short - circuit resistance data of the cell under test to obtain normalized data.

[0264] The above - mentioned first example:

[0265] Calculate the average value of the internal short - circuit resistance of the above 5 cells to be 6715.78449 Ω, the standard deviation to be 592.6337007, and the z - scores of the internal short - circuit resistances of the 5 cells are 1.99700249, 2.010331593, - 7.999992823 (corresponding to the cell under test), 1.99566958, 1.996989161 respectively.

[0266] The above - mentioned second example:

[0267] Calculate the average value of the internal short - circuit resistance of the above 5 cells to be 4882.923273 Ω, the standard deviation to be 430.8930541, and the z - scores of the internal short - circuit resistances of the 5 cells are 1.99700249, 2.010331593, - 7.999992823 (corresponding to the cell under test), 1.99566958, 1.996989161 respectively.

[0268] (6) Detect whether the cell under test has an internal short - circuit according to the normalized data.

[0269] For example, since the z - score of the cell under test in the above - mentioned first example is - 7.999992823 and is less than the first threshold (which is - 6), it can be determined that the cell under test corresponding to this z - score has an internal short - circuit, and it can be determined that the battery to which the cell under test belongs is abnormal.

[0270] Also, for example, since the z - score of the cell under test in the above - mentioned second example is - 7.999992823 and is less than the first threshold (which is - 6), it can be determined that the cell under test corresponding to this z - score has an internal short - circuit, and it can be determined that the battery to which the cell under test belongs is abnormal.

[0271] (7) For the cell under test that has been confirmed to have an internal short - circuit, the cell under test with the internal short - circuit can be controlled to stop working manually or through the server.

[0272] In summary, for the internal short - circuit detection method of the battery cell provided in the embodiments of the present application, the internal short - circuit internal resistance that cannot be directly measured can be calculated from the easily measurable voltage, current, and temperature data, and the severity of the internal short - circuit of the battery cell is quantified by normalizing the internal short - circuit resistance data of the battery cell to be measured, so as to detect whether an internal short - circuit occurs in the battery cell to be measured, thereby realizing real - time identification of internal short - circuit anomalies in more scenarios (or all scenarios).

[0273] It should be understood that the magnitudes of the sequence numbers of the steps in the above - mentioned embodiments do not mean the order of execution. The order of execution of each process should be determined by its function and internal logic, and should not constitute any limitation to the implementation process of the embodiments of the present application.

[0274] In some embodiments of the present application, an internal short - circuit detection device for a battery cell is provided. The internal short - circuit detection device for a battery cell includes modules for executing the method steps in any of the above - mentioned method embodiments.

[0275] In the internal short - circuit detection device for a battery cell provided in the embodiments of the present application, the process of each module realizing its respective function can be specifically referred to the descriptions of the foregoing Figure 2 illustrated embodiments and other related method embodiments, and will not be elaborated here.

[0276] The internal short - circuit detection device for a battery cell provided in the embodiments of the present application also has the above - mentioned beneficial effects, that is, it does not interfere with the normal use conditions of the battery and can identify abnormal battery cells with internal short - circuits in more scenarios in real - time.

[0277] The internal short - circuit detection method provided in the embodiments of the present application can be applied to devices such as BMS, electrical equipment including BMS, energy storage equipment including BMS, or servers.

[0278] Figure 10 It is a schematic structural diagram of a server provided in an embodiment of the present application. As Figure 10 shown, the server 120 in this embodiment includes: at least one processor 121 ( Figure 10 only one is shown here), a memory 122, and a computer program 123 stored in the memory 122 that can run on the processor 121. When the processor 121 executes the computer program 123, it implements the steps in the above - mentioned internal short - circuit detection method embodiment, such as Figure 2 the steps S110 - S130 shown.

[0279] The server 120 may include but is not limited to the processor 121 and the memory 122. Those skilled in the art can understand that Figure 10The server 120 is merely an example and does not limit the server 120. It may include more or fewer components than those shown in the figure, or combine certain components, or have different components. For example, the server may also include an input sending device, a network access device, a bus, etc.

[0280] The so-called processor 121 may be a central processing unit (CPU), or may also be other general-purpose processors, digital signal processors (DSPs), application specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or the processor may also be any conventional processor, etc.

[0281] In some embodiments, the memory 122 may be an internal storage unit of the server 120, such as the hard disk or memory of the server 120. The memory 122 may also be an external storage device of the server 120, such as a plug-in hard disk equipped on the server 120, a smart media card (SMC), a secure digital (SD) card, a flash card, etc. Further, the memory 122 may also include both the internal storage unit and the external storage device of the server 120. The memory 122 is used to store an operating system, application programs, a boot loader, data, and other programs, such as the program code of a computer program. The memory 122 may also be used to temporarily store data that has been sent or will be sent.

[0282] The embodiments of the present application also provide a computer-readable storage medium. The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps in the above-mentioned method embodiments can be implemented.

[0283] The embodiments of the present application also provide a BMS, including: a memory, a processor, and a program stored on the memory and executable on the processor. When the processor executes the program, the steps in the above-mentioned method embodiments can be implemented.

[0284] The embodiments of the present application also provide an electrical device, including a battery cell to be measured and the above-mentioned BMS.

[0285] An embodiment of the present application further provides an energy storage device, including a battery cell to be measured and the above-mentioned BMS.

[0286] The above embodiments are only used to illustrate the technical solutions of the present application, rather than limiting them; although the present application 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 described in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A method for detecting internal short circuit in an electric cell, characterized in that, it includes: Obtaining the internal short circuit resistance data of the electric cell to be measured; Based on the reference data, normalizing the internal short circuit resistance data of the electric cell to be measured to obtain the normalized data of the electric cell to be measured, where the reference data includes the internal short circuit resistance data of a reference electric cell, and the reference electric cell and the electric cell to be measured are under the same working conditions; According to the normalized data, detecting whether the electric cell to be measured has an internal short circuit.

2. The method for detecting internal short circuit in an electric cell according to claim 1, characterized in that, after detecting whether the electric cell to be measured has an internal short circuit according to the normalized data, it further includes: According to the detection result of whether the electric cell to be measured has an internal short circuit, detecting whether the battery to which the electric cell to be measured belongs is abnormal.

3. The method for detecting internal short circuit in an electric cell according to claim 1 or 2, characterized in that, the method further includes: Based on the current working condition of the electric cell to be measured, determining the reference electric cell; Obtaining the internal short circuit resistance data of the reference electric cell to obtain the reference data.

4. The method for detecting internal short circuit in an electric cell according to claim 3, characterized in that, determining the reference electric cell based on the current working condition of the electric cell to be measured includes: Based on the working condition parameters of the battery to which the electric cell to be measured belongs, determining at least one electric cell included in the target battery as the reference electric cell, where the working condition parameters of the target battery are the same as those of the battery to which the electric cell to be measured belongs, and the working condition parameters include at least one of state of charge, temperature, current, and humidity.

5. The method for detecting internal short circuit in an electric cell according to any one of claims 1 to 4, characterized in that, normalizing the internal short circuit resistance data based on the reference data to obtain the normalized data of the electric cell to be measured is: Based on the reference data, solving the z-score or entropy of the internal short circuit resistance data of the electric cell to be measured to obtain the normalized data of the electric cell to be measured.

6. The method for detecting internal short circuit in an electric cell according to any one of claims 1 to 4, characterized in that, normalizing the internal short circuit resistance data of the electric cell to be measured based on the reference data to obtain the normalized data of the electric cell to be measured includes: Performing outlier statistics on the reference data and the internal short circuit resistance data of the electric cell to be measured to obtain the normalized data of the electric cell to be measured.

7. The method for detecting internal short circuit in an electric cell according to any one of claims 1 to 6, characterized in that, obtaining the internal short circuit resistance data of the electric cell to be measured includes: Obtaining the state data of the electric cell to be measured, where the state data includes internal short circuit voltage, normal voltage, and ohmic internal resistance; According to the state data and the first functional relationship between the state data and the internal short circuit resistance of the electric cell to be measured, determining the internal short circuit resistance data of the electric cell to be measured.

8. The method for detecting internal short circuit in an electric cell according to claim 7, characterized in that, the method for determining the normal voltage includes: Based on the equivalent circuit model of a normal electric cell, determining the normal voltage of the electric cell to be measured; or, Based on the electrochemical model of a normal electric cell, determining the normal voltage of the electric cell to be measured; or, Determine the normal voltage of the cell under test from the historical data of the cell under test, where the historical data includes the normal voltage of the cell under test.

9. The method for detecting internal short circuit of a cell according to claim 8, wherein, determining the normal voltage of the cell under test based on the equivalent circuit model of a normal cell includes: determining the open-circuit voltage according to the state of charge of the cell under test and the second functional relationship between the state of charge and the open-circuit voltage of the cell under test; determining the normal voltage according to the ohmic internal resistance, open-circuit voltage and current of the cell under test.

10. The method for detecting internal short circuit of a cell according to any one of claims 7 to 9, wherein, the method for determining the ohmic internal resistance of the cell under test includes: acquiring the state of charge and temperature of the cell under test; determining the ohmic internal resistance according to the state of charge and temperature of the cell under test and the third functional relationship between the state of charge, temperature and ohmic internal resistance.

11. The method for detecting internal short circuit of a cell according to any one of claims 1 to 10, wherein, after detecting whether the cell under test has an internal short circuit according to the normalized data, further includes: when the detection result is that the cell under test has an internal short circuit, controlling the cell under test to stop working.

12. An apparatus for detecting internal short circuit of a cell, wherein, it includes a module for executing the method according to any one of claims 1 to 11.

13. A battery management system, wherein, it includes a memory, a processor, and a program stored on the memory and executable on the processor. When the processor executes the program, the method according to any one of claims 1 to 11 is implemented.

14. An electrical device, wherein, it includes a cell under test and the battery management system according to claim 13.

15. An energy storage device, wherein, it includes a cell under test and the battery management system according to claim 13.

16. A server, wherein, it includes a memory, a processor, and a program stored on the memory and executable on the processor. When the processor executes the program, the method according to any one of claims 1 to 11 is implemented.

17. A computer-readable storage medium, wherein, the computer-readable storage medium stores a program, and when the program is executed by a processor, the method according to claims 1 to 11 is implemented.

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