Method and device for detecting micro-short circuit of battery cell, electronic equipment and storage medium

Abstract

The application provides a battery cell micro-short circuit detection method, device, electronic equipment and storage medium, and relates to the technical field of battery cell detection. The battery cell micro-short circuit detection method comprises the following steps: counting the probability of occurrence of each voltage of the battery cell in a first charging stage; the charging process of the battery cell comprises a second charging stage and the first charging stage; the charging current of the first charging stage is smaller than the charging current of the second charging stage; the maximum peak probability is selected from all the probabilities; and the micro-short circuit of the battery cell is determined in the case that the peak probability exceeds a preset range. In the embodiment of the application, the probability of occurrence of each voltage of the battery cell is easy to obtain, so the method can be applied to most battery cells and has a wide range of application. In the first charging stage, the voltage of the battery cell is usually large, and the micro-short circuit of the battery cell is more obvious, so the detection of the micro-short circuit of the battery cell is more accurate.

Description

Technical Field

[0001] This invention relates to the field of battery cell testing technology, and in particular to a method, apparatus, electronic device, and storage medium for detecting micro short circuits in battery cells. Background Technology

[0002] Micro-short circuit faults inside battery cells mainly originate from two aspects. Firstly, defects such as the intrusion of metal foreign objects or redundant tabs during the manufacturing process can cause micro-short circuits in the contact between the positive and negative electrodes of the internal winding core. Secondly, after prolonged use, cell aging, accompanied by defects such as lithium plating and excessive local stress, can lead to diaphragm puncture and trigger localized micro-short circuits in the winding core. Micro-short circuit phenomena may worsen after vehicle vibration or frequent fast charging, manifesting externally as a noticeable voltage drop and heat generation. In severe cases, it can directly cause safety accidents such as cell fires and explosions. Therefore, micro-short circuit detection of battery cells is essential.

[0003] Currently, the main method for detecting micro-short circuits in battery cells is to statistically analyze the voltage changes of the battery cell under long-term static conditions, and then determine whether the self-discharge is normal based on empirical thresholds, thereby determining whether the battery cell has experienced a micro-short circuit fault.

[0004] However, the above testing methods have poor applicability because the battery cells need to be left to stand for a long time, which is difficult to achieve when the battery cells need to be used frequently. Summary of the Invention

[0005] This invention provides a method, apparatus, electronic device, and storage medium for detecting micro short circuits in battery cells, aiming to solve the problem of poor adaptability of existing methods for detecting micro short circuits in battery cells.

[0006] A first aspect of the present invention provides a method for detecting micro-short circuits in a battery cell, comprising:

[0007] The probability of each voltage of the battery cell occurring during the first charging stage is statistically analyzed; the charging process of the battery cell includes a second charging stage and a first charging stage; the charging current of the first charging stage is less than the charging current of the second charging stage.

[0008] From all the probabilities mentioned, select the highest peak probability;

[0009] If the peak probability exceeds a preset range, it is determined that a micro short circuit has occurred in the battery cell.

[0010] In this embodiment of the invention, determining whether a battery cell has experienced a micro-short circuit involves using the probability of each voltage of the battery cell occurring during the first charging stage. Since batteries require charging when their charge is low, the probabilities of each voltage occurring during the first charging stage are readily available, making this method applicable to the vast majority of battery cells and thus having a wide range of applications. Furthermore, this invention only requires the probabilities of each voltage occurring during the first charging stage and a preset range to detect whether a micro-short circuit has occurred, making the micro-short circuit detection method simple. Moreover, during the charging process, the charging current typically decreases as charging continues. The charging process of this battery cell includes a first charging stage and a second charging stage. The charging current in the first charging stage is smaller than the charging current in the second charging stage. Therefore, the voltage of the battery cell is usually higher in the first charging stage, making micro-short circuits more apparent and thus more accurate in detecting them. During this first charging phase, the voltage change of the battery cell is usually relatively gradual. The impact of voltage changes on the misjudgment of micro-short circuits is negligible, which further improves the accuracy of micro-short circuit detection.

[0011] Optionally, the battery cell can be any cell in the battery system, and the probability of each voltage of the battery cell occurring during the first charging stage includes:

[0012] For each cell in the battery system, the probability of each voltage of the cell occurring during the first charging stage is calculated.

[0013] The step of selecting the largest peak probability from all said probabilities includes:

[0014] For each cell in the battery system, the highest peak probability is selected from all probabilities of that cell;

[0015] Before determining that a micro-short circuit has occurred in the battery cell when the peak probability exceeds a preset range, the method further includes:

[0016] The preset range is determined based on all probabilities corresponding to all cells in the battery system.

[0017] The step of determining that the battery cell has experienced a micro-short circuit when the peak probability exceeds a preset range includes:

[0018] For each cell in the battery system, if the peak probability of the cell exceeds the preset range, it is determined that the cell has a micro-short circuit.

[0019] Optionally, determining the preset range based on all probabilities corresponding to all cells in the battery system includes:

[0020] Calculate the average probability and variance of all probabilities corresponding to all cells in the battery system;

[0021] The preset range is determined based on the average probability and variance.

[0022] Optionally, for each cell in the battery system, calculating the probability of each voltage of the cell occurring during the first charging stage includes:

[0023] For each cell in the battery system during each charging cycle, the probability of each voltage of the cell occurring during the first charging phase of that charging cycle is calculated.

[0024] For each cell in the battery system, selecting the highest peak probability from all probabilities for that cell includes:

[0025] For each charge of each cell in the battery system, the highest peak probability is selected from all probabilities corresponding to that charge of the cell.

[0026] The step of determining the preset range based on all probabilities corresponding to all cells in the battery system includes:

[0027] Based on each charge of each cell in the battery system, and all the probabilities corresponding to each charge of all cells, the preset range corresponding to the next charge is determined;

[0028] The step of determining that a micro-short circuit has occurred in each cell of the battery system when the peak probability of the cell exceeds the preset range includes:

[0029] For each cell in the battery system during each charge, if the peak probability of the charge of the cell exceeds the preset range corresponding to the charge, it is determined that the cell has experienced a micro-short circuit during the charge.

[0030] For each cell in the battery system, if a micro-short circuit occurs in all charging cycles of the cell within a preset number of charging cycles, then the cell is determined to have experienced a micro-short circuit.

[0031] Optionally, in all the charging cycles, there is a time interval between two adjacent charging cycles; among all the time intervals corresponding to all the charging cycles, there are at least two different time intervals; the sorting result of the at least two different time intervals in descending order is the same as the sorting result of the at least two different time intervals in ascending order.

[0032] Optionally, the probability of each voltage of the battery cell occurring during the first charging stage includes:

[0033] The probability of each voltage level occurring during the first charging phase of the battery cell, specifically the portion where the battery cell voltage first decreases and then increases.

[0034] Optionally, determining the preset range based on the average probability and variance includes:

[0035] The set defined by subtracting three times the variance from the average probability and adding three times the variance to the average probability is determined as the preset range.

[0036] Optionally, the first charging phase includes a trickle charging phase.

[0037] Optionally, determining that a cell has a micro-short circuit during all charging cycles for each cell in the battery system, provided that a micro-short circuit occurs in each cell during a preset number of charging cycles, includes:

[0038] For each cell in the battery system, if a micro-short circuit occurs in the cell during at least one charge, it is determined that the cell has experienced a micro-short circuit.

[0039] Optionally, the charging current in the first charging stage is less than or equal to the constant current corresponding to the constant current used to fully charge the battery cell within a preset time period at room temperature.

[0040] A second aspect of the present invention provides a device for detecting micro-short circuits in battery cells, comprising:

[0041] The statistics module is used to calculate the probability of each voltage of the battery cell occurring during the first charging stage; the charging process of the battery cell includes a second charging stage and a first charging stage; the charging current of the first charging stage is less than the charging current of the second charging stage.

[0042] The selection module is used to select the largest peak probability from all the probabilities stated.

[0043] The micro-short circuit determination module is used to determine that a micro-short circuit has occurred in the battery cell when the peak probability exceeds a preset range.

[0044] A third aspect of the present invention provides an electronic device comprising:

[0045] A processor, a memory, and a computer program stored in the memory and executable on the processor, wherein the processor, when executing the program, implements any of the aforementioned methods for detecting micro-short circuits in a battery cell.

[0046] In a fourth aspect, the present invention provides a readable storage medium that, when instructions in the storage medium are executed by a processor of an electronic device, enables the electronic device to perform any of the aforementioned methods for detecting micro-short circuits in a battery cell.

[0047] In this invention, the method for detecting micro short circuits in battery cells, the device for detecting micro short circuits in battery cells, the electronic device, and the readable storage medium all have the same or similar beneficial effects, and will not be described again here to avoid repetition. Attached Figure Description

[0048] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0049] Figure 1 A flowchart illustrating the steps of a method for detecting micro-short circuits in a battery cell according to an embodiment of the present invention is shown.

[0050] Figure 2 This invention illustrates a schematic diagram of parameter changes during the charging process of a battery cell in an embodiment of the present invention.

[0051] Figure 3 This diagram illustrates parameter changes during a first charging stage in an embodiment of the present invention.

[0052] Figure 4 A flowchart illustrating the steps of another method for detecting micro-short circuits in a battery cell according to an embodiment of the present invention is shown.

[0053] Figure 5 This diagram illustrates the parameter changes during the first charging phase of all cells in a battery system according to an embodiment of the present invention.

[0054] Figure 6 This diagram illustrates the probability of each voltage occurring during the first charging stage of the three battery cells in an embodiment of the present invention.

[0055] Figure 7 This invention illustrates a schematic diagram of the peak probability distribution for each cell in a battery system according to an embodiment of the present invention.

[0056] Figure 8This invention illustrates another distribution diagram of the peak probability corresponding to each cell in a battery system according to an embodiment of the present invention;

[0057] Figure 9 A structural block diagram of an embodiment of a battery cell micro-short circuit detection device according to the present invention is shown. Detailed Implementation

[0058] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0059] This invention provides a method for detecting micro-short circuits in battery cells. Figure 1 A flowchart illustrating the steps of a method for detecting micro-short circuits in a battery cell according to an embodiment of the present invention is shown. (Refer to...) Figure 1 The method for detecting micro-short circuits in the battery cell may include the following steps.

[0060] Step 101: Calculate the probability of each voltage of the battery cell occurring during the first charging stage; the charging process of the battery cell includes: a second charging stage and the first charging stage; the charging current of the first charging stage is less than the charging current of the second charging stage.

[0061] During the charging process, to meet consumers' fast charging demands, the initial charging current is typically higher. As the battery capacity increases, the charging current usually decreases to avoid overcharging and other safety hazards. In this invention, the charging process of the battery cell includes a second charging stage and a first charging stage. The charging current in the first charging stage is less than the charging current in the second charging stage, indicating that the second charging stage is an earlier charging stage, while the first charging stage is a later stage or one that is closer to a fully charged state. The specific value of the difference between the charging current in the second charging stage and the charging current in the first charging stage is not limited here.

[0062] Figure 2 This diagram illustrates the parameter changes during the charging process of a battery cell according to an embodiment of the present invention. Figure 2 The horizontal axis in the diagram can represent the charging duration, or the number of times the cell voltage or charging current was measured. Stepped charging 1 is the first step in this charging process, and stepped charging 6 is the last step in this charging process. Figure 2Part 'a' in the diagram refers to the upper part, which is a schematic diagram showing the change of the cell voltage with the charging time during the charging process. The vertical axis represents the cell voltage, and it can be concluded that the cell voltage increases with the increase of the charging duration. Figure 2 Part b, or the lower part, is a schematic diagram showing the change of charging current with charging time during the battery cell charging process. The vertical axis represents the charging current. It can be concluded that as the charging duration increases, the charging current decreases, and the closer to the fully charged state, the smaller the charging current becomes. Figure 2 During the charging process of the battery cell, the voltage and charging current of the cell were measured 5000 times. The sampling points were the serial numbers of either the voltage measurement or the charging current measurement. Figure 2 During the entire charging process, the cell voltage was measured 5000 times, resulting in 5000 voltage values. Simultaneously with each voltage measurement, the charging current was also measured, yielding 5000 charging current values. The intervals between adjacent measurements were approximately equal.

[0063] The inventors discovered that the early self-discharge current of a battery cell's micro-short circuit is very small, and the 'internal friction' phenomenon caused by micro-short circuit self-discharge during high-current charging is difficult to observe. Furthermore, the large battery capacity in current battery systems makes fault diagnosis even more challenging. Therefore, this invention selects the probability of each voltage occurring in the battery cell during the first charging stage, where the charging current is relatively small or the voltage is relatively large. The micro-short circuit is more pronounced in this stage, making its detection more accurate.

[0064] The probability of each voltage occurring in the battery cell during the first charging stage can be understood as: the number of times each voltage of the battery cell occurs during the first charging stage, measured at the same frequency. The higher the number of times a particular voltage occurs, the greater its probability of occurrence. It should be noted that if multiple voltage measurements yield equal values ​​but the measurement times are not adjacent, each voltage value is treated as a separate voltage and its probability of occurrence is calculated separately. If multiple voltage measurements yield equal values ​​and the measurement times are adjacent, these multiple voltage values ​​are treated as the same voltage and their probability of occurrence is calculated. The probability of a voltage can be directly obtained by taking the total number of times a voltage occurs, or by dividing the total number of times a voltage occurs by the total number of voltage measurements in the first stage.

[0065] Figure 3 This diagram illustrates parameter changes during a first charging stage in an embodiment of the present invention. Figure 3 The horizontal axis can represent the duration of the first charging phase, or the number of times the cell voltage and charging current were measured during the first charging phase. Figure 3Part 'a' in the diagram refers to the upper part, which is a schematic diagram showing the change of cell voltage with charging time during the first charging stage. The vertical axis represents the cell voltage, and it can be concluded that the cell voltage generally increases as the charging duration increases. Figure 3 Part b, or the lower part, is a schematic diagram showing the change of charging current with charging time during the first charging stage. The vertical axis represents the charging current. It can be concluded that the charging current decreases as the charging duration increases, and the closer to the fully charged state, the smaller the charging current becomes. Figure 3 In the first charging stage, the cell voltage and charging current were measured 1800 times. The sampling points were the cell voltage measurement count numbers or the charging current measurement count numbers. Figure 3 During the entire first charging phase, the cell voltage was measured 1800 times, resulting in 1800 voltage values. Simultaneously, the charging current was measured each time, yielding 1800 charging current values. The intervals between adjacent measurements were equal. For two voltage values ​​that were measured at adjacent times and differed by less than or equal to a preset difference, they could be treated as the same voltage value when calculating their probability of occurrence. This preset difference can be determined according to actual needs. For example, the preset difference could be less than or equal to 1mV (millivolts).

[0066] Step 102: Select the highest peak probability from all the probabilities.

[0067] This step involves selecting the peak probability with the highest value from the probabilities of each voltage occurring during the first charging stage.

[0068] Step 103: If the peak probability exceeds the preset range, determine that the cell has a micro short circuit.

[0069] The preset range here can be determined based on actual conditions, and is not specifically limited. The inventors discovered that, under normal circumstances, the probability of each voltage occurring during the first charging stage is roughly within a certain range. If the peak probability exceeds this preset range, it indicates that the battery cell may have a micro-short circuit fault.

[0070] In this embodiment of the invention, determining whether a battery cell has experienced a micro-short circuit involves using the probability of each voltage of the battery cell occurring during the first charging stage. Since batteries require charging when their charge is low, the probabilities of each voltage occurring during the first charging stage are readily available, making this method applicable to the vast majority of battery cells and thus having a wide range of applications. Furthermore, this invention only requires the probabilities of each voltage occurring during the first charging stage and a preset range to detect whether a micro-short circuit has occurred, making the micro-short circuit detection method simple. Moreover, during the charging process, the charging current typically decreases as charging continues. The charging process of this battery cell includes a first charging stage and a second charging stage. The charging current in the first charging stage is smaller than the charging current in the second charging stage. Therefore, the voltage of the battery cell is usually higher in the first charging stage, making micro-short circuits more apparent and thus more accurate in detecting them. During this first charging phase, the voltage change of the battery cell is usually relatively gradual. The impact of voltage changes on the misjudgment of micro-short circuits is negligible, which further improves the accuracy of micro-short circuit detection.

[0071] Optionally, in step 101 above, the first charging stage may include a trickle charging stage. This trickle charging stage can be the charging stage with the lowest charging current during the entire charging process of the battery cell, or the charging stage closest to a fully charged state. During the trickle charging stage, the charging current is the lowest; therefore, the voltage increase of the battery cell is slower, and thus, micro-short circuits in the battery cell are more pronounced, resulting in more accurate detection of micro-short circuits. In the trickle charging stage, the voltage change of the battery cell is usually relatively gradual, and the impact of voltage changes on misjudgments of micro-short circuits is negligible, further improving the accuracy of micro-short circuit detection. For example, referring to… Figure 2 As shown, the entire charging process of the battery cell includes six stages: stepped charging 1 to stepped charging 6. Stepped charging 6 is the last stage, and the charging current of stepped charging 6 is the smallest. The first charging stage can be stepped charging 6.

[0072] Optionally, in step 101 above, the charging current of the first charging stage can be less than or equal to the constant current corresponding to the constant current used to fully charge the cell within a preset time period at room temperature. Here, room temperature can be 25±3℃, and the preset time period can be 5 to 10 hours. This can be converted to a relationship corresponding to the cell capacity. For example, if the cell capacity is C, then at room temperature, 10 hours of constant current charging corresponds to a constant current of 0.1C. Under these conditions, the charging current of the first charging stage is smaller, the cell voltage increase is slower, and thus the micro-short circuit of the cell is more pronounced, resulting in more accurate detection of micro-short circuits. Because the charging current of the first charging stage is smaller, the cell voltage change is usually more gradual, and the impact of voltage changes on the misjudgment of micro-short circuits is negligible, further improving the accuracy of micro-short circuit detection.

[0073] For example, the charging current in the first charging stage can be less than or equal to the constant current required to fully charge the cell at room temperature for 10 hours. Alternatively, the charging current in the first charging stage can be less than or equal to the constant current required to fully charge the cell at room temperature for 9 hours. Alternatively, the charging current in the first charging stage can be less than or equal to the constant current required to fully charge the cell at room temperature for 8.5 hours. Alternatively, the charging current in the first charging stage can be less than or equal to the constant current required to fully charge the cell at room temperature for 7 hours. Alternatively, the charging current in the first charging stage can be less than or equal to the constant current required to fully charge the cell at room temperature for 6 hours. Alternatively, the charging current in the first charging stage can be less than or equal to the constant current required to fully charge the cell at room temperature for 5 hours.

[0074] Optionally, step 101 may include: calculating the probability of each voltage level occurring during the first charging phase, specifically the portion of the battery cell's voltage that initially decreases and then increases. For details, refer to... Figure 3 In part a of the invention, the inventors discovered that in almost every battery cell, during the first charging stage, the voltage initially decreases and then increases. The main reason is that the charging current in the first charging stage is smaller than in the second charging stage. Because the charging current decreases, the charging voltage also decreases initially. As the charging current continues to stimulate the cells, the voltage gradually increases. For normal battery cells, the voltage decrease and recovery trends are consistent. However, if there is a micro-short-circuited cell, because the charging current is larger in the second charging stage, the voltage decrease trend may not differ significantly. But because the micro-short-circuited cell is like a leaky bucket with continuous internal energy loss, its voltage increase may be slower during the charging ramp-up phase. Figure 3In the diagram, the two cell curves shown by the dashed circle exhibit slight differences. During the initial 40A charging segment, the voltage switches to 15A trickle charging at 4.284V, causing a continuous drop to 4.27V before rising again. During this process, the two cells spend the longest periods at 4.271V and 4.273V, respectively, for 50s and 42s. In other words, a micro-short-circuited cell may spend the longest time at a particular voltage. By statistically analyzing the difference in these two voltage levels, a micro-short-circuited cell can be identified. Therefore, in this first charging stage, the portion where the cell's voltage initially drops and then rises makes the micro-short circuit more pronounced and easier to detect, thus improving the accuracy of micro-short-circuit detection.

[0075] Figure 4 A flowchart illustrating the steps of another method for detecting micro-short circuits in a battery cell according to an embodiment of the present invention is shown. (Refer to...) Figure 4 The method for detecting micro-short circuits in the battery cell may include the following steps.

[0076] Step 201: The cell is any cell in the battery system. For each cell in the battery system, the probability of each voltage of the cell occurring in the first charging stage is calculated.

[0077] A battery system typically includes multiple cells. For example, a battery system composed of 1 parallel 96 series (1P96S) cells may have a capacity of 150 Ah (ampere-hours). The aforementioned 0.1C is 150 Ah × 0.1 = 15A. The cells in a battery system are usually used simultaneously or charged simultaneously. That is, the usage conditions of the cells in a battery system are quite similar. The number of cells in a battery system is not limited. This step involves, for each cell in the battery system, calculating the probability of each voltage occurring during the first charging stage. This step is similar to step 101 mentioned above.

[0078] For example, a battery system may have 100 cells. This step involves calculating the probability of each voltage of the cell occurring during the first charging stage for each of the 100 cells.

[0079] Figure 5 This diagram illustrates the parameter changes during the first charging phase of all cells in a battery system according to an embodiment of the present invention. Figure 5In the diagram, charging segments 1 to 7 represent the probability distributions of various voltages occurring in the seven first charging stages for all cells in a battery system at different time periods. The difference between each charging segment lies in the measurement time period. The measurement times for charging segments 1 to 7 are sequentially ordered, meaning that the measurement time for charging segment 1 is earlier than the measurement time for charging segment 2, and so on.

[0080] Figure 6 This diagram illustrates the probability of each voltage occurring during the first charging stage of the three battery cells in an embodiment of the present invention. Figure 6 In the image, the area enclosed by the dashed box represents the peak probability for each of the three battery cells. From... Figure 6 It can be concluded that the peak probabilities corresponding to the three cells are not equal, and each cell has a peak probability. The voltages of the three cells at the peak probabilities are also not equal.

[0081] Step 202: For each cell in the battery system, select the highest peak probability from all probabilities of the cell.

[0082] Step 202 is similar to the aforementioned step 102, except that for each cell in the battery system, the highest peak probability is selected from all probabilities of that cell.

[0083] For example, in the above case, for each of the 100 cells in a battery system, the highest peak probability is selected from all the probabilities of that cell.

[0084] Step 203: Determine the preset range based on all probabilities corresponding to all cells in the battery system.

[0085] In a battery system, all cells are used in similar conditions. Therefore, based on the probabilities corresponding to all cells in the battery system, a preset range is determined. This preset range then provides more targeted and accurate detection of micro-short circuits in each cell of the battery system. It should be noted that the application environment of this battery system is not limited. For example, the battery system can be a battery system in an electric vehicle. Using the micro-short circuit detection method of this invention, micro-short circuit faults can be accurately detected, allowing for early recall and location of the affected vehicles, effectively reducing the risk of accidents caused by micro-short circuits in the cells.

[0086] Optionally, step 203 may include steps 2031 and 2032. Step 2031: Calculate the average probability and variance of all probabilities corresponding to all cells in the battery system. Step 2032: Determine the preset range based on the average probability and variance.

[0087] Specifically, within the lifespan of a battery system, typically, a few individual cells may experience micro-short circuits, while the vast majority will not. In this battery system, the preset range is determined by the average probability and variance of all probabilities corresponding to all cells. This preset range reflects the average distribution of probabilities for each cell in the battery system as a whole. The inventors also discovered that the probability of a cell experiencing a micro-short circuit often exhibits outlier behavior. Therefore, by simply using the average probability and variance of all probabilities corresponding to all cells in a battery system, this preset range can be accurately and specifically determined. This method is simple, highly targeted, and highly accurate.

[0088] Optionally, step 2032 includes: determining the preset range by subtracting three times the variance from the average probability of all probabilities corresponding to all cells in the battery system, and by adding three times the aforementioned variance to the average probability. Specifically, in the battery system, the average probability of all probabilities corresponding to all cells is u, and the variance of all probabilities corresponding to all cells in the battery system is σ. The set (u-3σ, u+3σ) is then determined as the preset range for the battery system. More specifically, the inventors have found that, for all cells in the same battery system, setting the preset range within this range results in a more accurate and consistent detection of whether micro-short circuits occur in individual cells within the battery system.

[0089] Step 204: For each cell in the battery system, if the peak probability of the cell exceeds the preset range, determine that the cell has a micro short circuit.

[0090] Since this preset range can reflect the average distribution of the probability corresponding to each cell in the battery system as a whole, the preset range can be accurately determined in a targeted manner by simply using the average probability and variance of all probabilities corresponding to all cells in a battery system. This method is simple, highly targeted, and highly accurate.

[0091] Figure 7 This paper presents a schematic diagram showing the distribution of peak probabilities for each cell in a battery system according to an embodiment of the present invention. Figure 7 This is a schematic diagram comparing the peak probability and preset range for each of the 100 cells in the battery system within charging segment 1 of section 5. From... Figure 7 It can be concluded that the peak probabilities corresponding to the 100 cells of the battery system all fall within the preset range (u-3σ, u+3σ). In other words, none of the 100 cells of the battery system experienced a micro-short circuit fault at the time point corresponding to charging segment 1.

[0092] Figure 8 This paper presents another schematic diagram showing the peak probability distribution of each cell in a battery system according to an embodiment of the present invention. Figure 8 This is a schematic diagram comparing the peak probability and preset range for each of the 100 cells in the battery system within charging segment 5. From... Figure 8 It can be concluded that among the 100 cells in this battery system, only cell number 49 had a peak probability outside the preset range (u-3σ, u+3σ), while the packaging probabilities of the remaining cells all fell within the preset range (u-3σ, u+3σ). In other words, at the time point corresponding to charging segment 5, only cell number 49 experienced a micro-short circuit, while the other cells did not. Through actual verification, cell number 49 subsequently experienced a significant short circuit and overheating event, and lithium plating was found upon disassembly of cell number 49.

[0093] Figure 7 and Figure 8 All of these tests were conducted on 100 cells within the same battery system. Figure 7 The corresponding time is earlier than Figure 8 At the corresponding time, that is, for the same battery system, in the earlier tests, none of the cells in the battery system experienced micro-short circuits, but as the battery system continued to be used, some of the cells in the battery system experienced micro-short circuits.

[0094] Optionally, step 201 may include: step 2011, for each charge of each cell in the battery system, calculating the probability of each voltage of the cell occurring in the first charging stage of the next charge. Step 202 may include: step 2021, for each charge of each cell in the battery system, selecting the highest peak probability from all probabilities corresponding to the next charge of the cell. Step 203 may include: step 2033, determining the preset range corresponding to the next charge based on all probabilities corresponding to the next charge of all cells in each charge of the battery system. The aforementioned step 204 may include: step 2041, for each charge of each cell in the battery system, if the peak probability of the charge of the cell exceeds the preset range corresponding to the charge, determining that the cell has a micro short circuit in the charge; step 2042, for all charges of each cell in the battery system, if the cell has a micro short circuit in all charges within a preset number of charges, determining that the cell has a micro short circuit.

[0095] Specifically, this means further refining the micro-short circuit detection to each charge within a battery system. Each charge corresponds to a preset range, and then this preset range is used to evaluate whether a micro-short circuit occurs in each cell of the battery system during the first charging stage of that charge. The preset range here is determined for all cells in the charging system for that specific charge, making it more targeted and thus further improving the accuracy of detecting micro-short circuits in each cell of the battery system during the first charging stage of that charge.

[0096] It should be noted that the determination of the preset range corresponding to this charging system for this charging session can refer to the aforementioned record, except that its corresponding average probability and variance are both corresponding to this charging session.

[0097] In step 2041 above, the preset number of times is determined based on actual needs. A larger preset number can avoid false detections and further improve detection accuracy, while a smaller preset number can appropriately improve security. The selection of this preset number is determined based on the actual situation.

[0098] Optionally, step 2041 may include: for all charging cycles of each cell in the battery system, if a cell experiences a micro-short circuit in at least one charging cycle, determining that the cell has experienced a micro-short circuit. That is, for all charging cycles of each cell in the battery system, if a cell experiences a micro-short circuit in even one charging cycle, it is determined that the cell has experienced a micro-short circuit, which can further improve safety.

[0099] Optionally, in step 2042, there is a time interval between two adjacent charges in all sub-charges; among all the time intervals corresponding to all sub-charges, there are at least two different time intervals; the sorting result of the at least two different time intervals in descending order is the same as the sorting result of the at least two different time intervals in ascending order. That is to say, in the statistical analysis of the probability of voltage occurrence of the battery cell in the first charging stage, the earlier the statistical time, the longer the interval between two adjacent statistical analyses may be; the later the statistical time, the shorter the interval between two adjacent statistical analyses may be. Specifically, the inventors found that as the battery cell is used, the longer the battery cell is used, the greater the probability of micro-short circuits. At the same time, micro-short circuits are not easy to detect in the early stages, and they may not easily occur. Moreover, with the continuous use of the battery cell and the passage of time, the self-discharge phenomenon becomes more and more obvious. Therefore, by observing the peak probability corresponding to the battery cell for a long time, the micro-short circuit phenomenon that was not easy to observe before will surface. Therefore, the later the statistical time, the shorter the interval between two adjacent statistics, the better it matches the pattern of micro-short circuits in the battery cell. This not only avoids unnecessary statistical waste but also enables the detection of micro-short circuits in the battery cell as soon as possible.

[0100] For example, regarding the aforementioned Figure 5 The seven charging segments shown represent the probability of each voltage occurring in all cells of the battery system during the first charging stage. The statistical time corresponding to charging segment 1 is earlier than that corresponding to charging segment 2, which is earlier than charging segment 3, which is earlier than charging segment 4, which is earlier than charging segment 5, which is earlier than charging segment 6, and which is earlier than charging segment 7. The time interval between the statistical time of charging segment 1 and that of charging segment 2, between the statistical time of charging segment 2 and that of charging segment 3, and between the statistical time of charging segment 3 and that of charging segment 4 are all three weeks. The statistical time corresponding to charging segment 4 and the time interval between the statistical time corresponding to charging segment 5, the time interval between the statistical time corresponding to charging segment 5 and the statistical time corresponding to charging segment 6, and the time interval between the statistical time corresponding to charging segment 6 and the statistical time corresponding to charging segment 7 are all 3 days. In the early stage, the time interval between adjacent statistical times is longer, and in the later stage, the time interval between adjacent statistical times is shorter, which is more consistent with the pattern of micro short circuits in the battery cell. This not only avoids unnecessary statistical waste, but also enables the battery cell micro short circuits to be detected as soon as possible.

[0101] It should be noted that, for the sake of simplicity, the method embodiments are all described as a series of actions. However, those skilled in the art should understand that the embodiments of this application are not limited to the described order of actions, because according to the embodiments of this application, some steps can be performed in other orders or simultaneously. Secondly, those skilled in the art should also understand that the embodiments described in the specification are all preferred embodiments, and the actions involved are not necessarily essential to the embodiments of this application.

[0102] Reference Figure 9 , Figure 9 The diagram shows a structural block diagram of an embodiment of a battery cell micro-short circuit detection device according to the present invention, which may specifically include the following modules:

[0103] The statistics module 301 is used to calculate the probability of each voltage of the battery cell occurring during the first charging stage; the charging process of the battery cell includes a second charging stage and the first charging stage; the charging current of the first charging stage is less than the charging current of the second charging stage.

[0104] Selection module 302 is used to select the largest peak probability from all the probabilities;

[0105] The micro-short circuit determination module 303 is used to determine that a micro-short circuit has occurred in the battery cell when the peak probability exceeds a preset range.

[0106] Optionally, the statistics module 301 includes:

[0107] The first statistics submodule is used to calculate the probability of each voltage of the battery cell occurring during the first charging stage for each cell in the battery system.

[0108] The selection module 302 includes:

[0109] The selection submodule is used to select the highest peak probability from all probabilities of each cell in the battery system.

[0110] The device further includes:

[0111] The preset range determination module is used to determine the preset range based on all probabilities corresponding to all cells in the battery system.

[0112] The micro-short circuit determination module 303 includes:

[0113] The micro-short circuit determination submodule is used to determine that a micro-short circuit has occurred in each cell of the battery system when the peak probability of the cell exceeds the preset range.

[0114] Optionally, the preset range determination module includes:

[0115] The calculation submodule is used to calculate the average probability and variance of all probabilities corresponding to all cells in the battery system;

[0116] The first preset range determination submodule is used to determine the preset range based on the average probability and variance.

[0117] Optionally, the first statistics submodule includes:

[0118] The statistics unit is used to calculate the probability of each voltage of the cell occurring in the first charging stage of each charging cycle for each cell in the battery system.

[0119] The selection submodule includes:

[0120] The selection unit is used to select the highest peak probability from all probabilities corresponding to each charge of each cell in the battery system for each charge.

[0121] The preset range determination module includes:

[0122] The second preset range determination submodule is used to determine the preset range corresponding to the next charge based on each charge of each cell in the battery system and all the probabilities corresponding to the next charge of all cells.

[0123] The micro-short circuit determination submodule includes:

[0124] A micro-short circuit determination unit for each cell in the battery system is used to determine that a micro-short circuit has occurred in the cell during each charge if the peak probability of the cell during the charge exceeds the preset range corresponding to the charge.

[0125] The micro-short circuit determination unit is used to determine that a micro-short circuit has occurred in a cell during all charging cycles of each cell in the battery system, provided that a micro-short circuit has occurred in the cell during a preset number of charging cycles.

[0126] Optionally, in all the charging cycles, there is a time interval between two adjacent charging cycles; among all the time intervals corresponding to all the charging cycles, there are at least two different time intervals; the sorting result of the at least two different time intervals in descending order is the same as the sorting result of the at least two different time intervals in ascending order.

[0127] Optionally, the statistics module includes:

[0128] The second statistical submodule is used to calculate the probability of each voltage of the battery cell occurring during the first charging stage, when the battery cell voltage first decreases and then increases.

[0129] Optionally, the preset range first determining submodule includes:

[0130] The preset range determination unit is used to determine the set defined by subtracting three times the variance from the average probability and adding three times the variance to the average probability as the preset range.

[0131] Optionally, the first charging phase includes a trickle charging phase.

[0132] Optionally, the micro-short circuit determination unit includes:

[0133] A micro-short circuit determination subunit is used to determine if a micro-short circuit has occurred in a cell during at least one charge of each cell in the battery system, for all charges.

[0134] Optionally, the charging current in the first charging stage is less than or equal to the constant current corresponding to the constant current used to fully charge the battery cell within a preset time period at room temperature.

[0135] As the device embodiment is basically similar to the method embodiment, the description is relatively simple, and relevant parts can be found in the description of the method embodiment.

[0136] The present invention also provides an electronic device, comprising: a processor, a memory, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the steps of the above-described embodiments of the method for detecting micro-short circuits in battery cells.

[0137] The present invention also provides a readable storage medium, wherein when the instructions in the storage medium are executed by the processor of an electronic device, the electronic device is able to perform the steps of the above-described method for detecting micro short circuits in a battery cell.

[0138] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0139] Through the above description of the embodiments, those skilled in the art can clearly understand that the methods of the above embodiments can be implemented by means of software plus necessary general-purpose hardware platforms. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk), and includes several instructions to cause a terminal (which may be a mobile phone, computer, server, air conditioner, or network device, etc.) to execute the methods described in the various embodiments of the present invention.

[0140] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims. All of these forms are within the protection scope of the present invention.

Claims

1. A method for detecting micro-short circuits in a battery cell, characterized in that, include: The probability of each voltage of the battery cell occurring during the first charging stage is statistically analyzed. The charging process of the battery cell includes: a second charging stage and a first charging stage; the charging current of the first charging stage is less than the charging current of the second charging stage. From all the probabilities mentioned, select the highest peak probability; If the peak probability exceeds a preset range, it is determined that a micro short circuit has occurred in the battery cell.

2. The method for detecting micro-short circuits in a battery cell according to claim 1, characterized in that, The battery cell is any cell in the battery system. The probability of each voltage of the battery cell occurring during the first charging stage is statistically analyzed, including: For each cell in the battery system, the probability of each voltage of the cell occurring during the first charging stage is calculated. The step of selecting the largest peak probability from all said probabilities includes: For each cell in the battery system, the highest peak probability is selected from all probabilities of that cell; Before determining that a micro-short circuit has occurred in the battery cell when the peak probability exceeds a preset range, the method further includes: The preset range is determined based on all probabilities corresponding to all cells in the battery system. The step of determining that the battery cell has experienced a micro-short circuit when the peak probability exceeds a preset range includes: For each cell in the battery system, if the peak probability of the cell exceeds the preset range, it is determined that the cell has a micro-short circuit.

3. The method for detecting micro-short circuits in a battery cell according to claim 2, characterized in that, The step of determining the preset range based on all probabilities corresponding to all cells in the battery system includes: Calculate the average probability and variance of all probabilities corresponding to all cells in the battery system; The preset range is determined based on the average probability and variance.

4. The method for detecting micro-short circuits in a battery cell according to claim 2 or 3, characterized in that, For each cell in the battery system, the probability of each voltage of the cell occurring during the first charging phase is calculated, including: For each cell in the battery system during each charging cycle, the probability of each voltage of the cell occurring during the first charging phase of that charging cycle is calculated. For each cell in the battery system, selecting the highest peak probability from all probabilities for that cell includes: For each charge of each cell in the battery system, the highest peak probability is selected from all probabilities corresponding to that charge of the cell. The step of determining the preset range based on all probabilities corresponding to all cells in the battery system includes: Based on each charge of each cell in the battery system, and all the probabilities corresponding to each charge of all cells, the preset range corresponding to the next charge is determined; The step of determining that a micro-short circuit has occurred in each cell of the battery system when the peak probability of the cell exceeds the preset range includes: For each cell in the battery system during each charge, if the peak probability of the charge of the cell exceeds the preset range corresponding to the charge, it is determined that the cell has experienced a micro-short circuit during the charge. For each cell in the battery system, if a micro-short circuit occurs in all charging cycles of the cell within a preset number of charging cycles, then the cell is determined to have experienced a micro-short circuit.

5. The method for detecting micro-short circuits in a battery cell according to claim 4, characterized in that, In all the charging cycles, there is a time interval between two adjacent charging cycles; among all the time intervals corresponding to all the charging cycles, there are at least two different time intervals; the sorting result of the at least two different time intervals in descending order is the same as the sorting result of the at least two different time intervals in ascending order.

6. The method for detecting micro-short circuits in a battery cell according to any one of claims 1 to 3, characterized in that, The probability of each voltage of the battery cell occurring during the first charging stage is statistically analyzed, including: The probability of each voltage level occurring during the first charging phase of the battery cell, specifically the portion where the battery cell voltage first decreases and then increases.

7. The method for detecting micro-short circuits in a battery cell according to claim 3, characterized in that, Determining the preset range based on the average probability and variance includes: The set defined by subtracting three times the variance from the average probability and adding three times the variance to the average probability is determined as the preset range.

8. The method for detecting micro-short circuits in a battery cell according to any one of claims 1 to 3, characterized in that, The first charging stage includes a trickle charging stage.

9. The method for detecting micro-short circuits in a battery cell according to claim 4, characterized in that, The determination of a micro-short circuit in a cell during all charging cycles for each cell in the battery system, where a micro-short circuit occurs in each cell within a preset number of charging cycles, includes: For each cell in the battery system, if a micro-short circuit occurs in the cell during at least one charge, it is determined that the cell has experienced a micro-short circuit.

10. The method for detecting micro-short circuits in a battery cell according to any one of claims 1 to 3, characterized in that, The charging current in the first charging stage is less than or equal to the constant current corresponding to the constant current that fills the cell at a constant current within a preset time at room temperature.

11. A device for detecting micro-short circuits in battery cells, characterized in that, include: The statistics module is used to calculate the probability of each voltage of the battery cell occurring during the first charging stage. The charging process of the battery cell includes: a second charging stage and a first charging stage; the charging current of the first charging stage is less than the charging current of the second charging stage. The selection module is used to select the largest peak probability from all the probabilities stated. The micro-short circuit determination module is used to determine that a micro-short circuit has occurred in the battery cell when the peak probability exceeds a preset range.

12. An electronic device, characterized in that, include: A processor, a memory, and a computer program stored in the memory and executable on the processor, characterized in that, when the processor executes the program, it implements a method for detecting micro-short circuits in a battery cell as described in any one of claims 1-10.

13. A readable storage medium, characterized in that, When the instructions in the storage medium are executed by the processor of the electronic device, the electronic device is able to perform the cell micro-short circuit detection method according to any one of claims 1-10.

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