Method and apparatus for detecting a failed battery in a battery pack

Abstract

The application discloses a method and device for detecting a fault battery in a battery pack. The voltage of each battery string is collected to determine N voltage arrays, and then the battery string with a fault is determined according to the bit order change of the voltage in each voltage array. In this way, the battery string with a fault can be determined based on the voltage data, the fault can be identified in advance from the data end, and the battery string with a fault can be accurately located, so that early warning and intervention can be made before an accident occurs, thereby improving the safety of the battery pack in use.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and more particularly to a method and apparatus for detecting faulty batteries in a battery pack. Background Technology

[0002] Electric vehicles are typically powered by battery packs, which contain multiple individual cells. During the use of the battery pack, if a single cell malfunctions (such as an open circuit), it will cause a sudden or continuous drop in the voltage of the entire vehicle under various operating conditions. Because this voltage drop is relatively insignificant, the battery management system may have difficulty identifying it and thus be unable to take effective measures, leading to more dangerous situations and greatly reducing the safety of electric vehicles.

[0003] Therefore, how to identify faulty batteries in a battery pack is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0004] This invention provides a method and apparatus for detecting faulty batteries in a battery pack, used to identify faulty batteries in the battery pack.

[0005] In a first aspect, embodiments of the present invention provide a method for detecting faulty batteries in a battery pack, wherein the battery pack includes multiple battery strings connected in series, each battery string including at least one individual battery cell, and when the battery string includes multiple individual batteries, the multiple individual batteries are connected in parallel; the detection method includes:

[0006] Within a first preset time period, the voltage of each battery string is collected according to a preset collection cycle, and N voltage arrays are determined in chronological order of collection time; wherein each voltage array includes the voltage of each battery string after being sorted in size order; when the first preset time period includes M collection cycles, M is a positive integer not less than N;

[0007] The faulty battery string is determined based on the change in the position of the voltage in each of the voltage arrays.

[0008] Secondly, embodiments of the present invention provide a device for detecting faulty batteries in a battery pack, comprising:

[0009] Memory, used to store program instructions;

[0010] The processor is configured to call the program instructions stored in the memory and execute the detection method described above as provided in the embodiments of the present invention according to the obtained program.

[0011] Thirdly, embodiments of the present invention provide an electric device, including: a detection device for faulty batteries in a battery pack as described in the embodiments of the present invention.

[0012] The technical effects that the above technical solution can achieve include:

[0013] This invention provides a method and apparatus for detecting faulty batteries in a battery pack. By collecting the voltage of each battery string, N voltage arrays are determined. Then, based on the change in the position of the voltage in each voltage array, the faulty battery string is determined. In this way, the faulty battery string can be determined based on the voltage data, realizing early identification of faults and accurate location of faulty battery strings from the data end. This allows for early warning and intervention before an accident occurs, thereby improving the safety of the battery pack during use. Attached Figure Description

[0014] Figure 1 This is a schematic diagram illustrating the connection relationship of individual cells in a battery pack provided in an embodiment of the present invention;

[0015] Figure 2 This is a flowchart of a detection method provided in an embodiment of the present invention;

[0016] Figure 3 This is a diagram showing the relationship between position and time provided in an embodiment of the present invention;

[0017] Figure 4 for Figure 3 Internal diagram of the faulty battery within the corresponding battery string;

[0018] Figure 5 This is another diagram showing the relationship between position and time provided in an embodiment of the present invention;

[0019] Figure 6 for Figure 5 Internal diagram of the faulty battery within the corresponding battery string;

[0020] Figure 7 This is a schematic diagram of the structure of a detection device provided in an embodiment of the present invention;

[0021] Figure 8 This is a schematic diagram of the structure of an electric device provided in an embodiment of the present invention. Detailed Implementation

[0022] The specific implementation methods and apparatus for detecting faulty batteries in a battery pack provided by the present invention will be described in detail below with reference to the accompanying drawings. It should be noted that the described embodiments are merely some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0023] This invention provides a method for detecting faulty batteries in a battery pack, wherein, as shown in the embodiments of the present invention... Figure 1 As shown, the battery pack includes multiple battery strings connected in series (e.g., C1, C2, and C3 represent three battery strings), each battery string including at least one individual cell. When a battery string includes multiple individual cells (e.g., battery strings C1 and C2), the multiple individual cells are connected in parallel; wherein, Figure 1 D1, D2, D3, D4, D5, and D6 in the diagram all represent individual cells.

[0024] like Figure 2 As shown, the detection method may include:

[0025] S201. Within a first preset time period, the voltage of each battery string is collected according to a preset collection cycle, and N voltage arrays are determined in chronological order of collection time; wherein, each voltage array includes the voltage of each battery string after being sorted in size order; when the first preset time period includes M collection cycles, M is a positive integer not less than N.

[0026] Specifically, in this embodiment of the invention, each battery string can be numbered to distinguish each battery string.

[0027] Specifically, the data collection period can be set according to actual needs, such as, but not limited to, 10 seconds (i.e., data collection every 10 seconds), 20 seconds, or 30 seconds, etc., and is not limited here.

[0028] S202. Determine the faulty battery string based on the change in the position of the voltage in each voltage array.

[0029] By collecting the voltage of each battery string, N voltage arrays are determined. Then, based on the change in the position of the voltage in each voltage array, the faulty battery string is identified. In this way, the faulty battery string can be identified based on the voltage data, realizing early identification of faults and accurate location of faulty battery strings from the data end. This allows for early warning and intervention before an accident occurs, thereby improving the safety of the battery pack during use.

[0030] Optionally, in this embodiment of the invention, determining the faulty battery string based on the change in the position of the voltage in each voltage array includes:

[0031] The voltage position is determined to reach a preset position within a second preset time; wherein the second preset time is less than the first preset time; the preset position is set close to the end of the voltage array with the lowest voltage.

[0032] The faulty battery string is determined based on its position before and after the voltage reaches the preset position.

[0033] If the voltages in the voltage array are arranged in ascending order, and the left end of the voltage array contains smaller voltages while the right end contains larger voltages, the preset position is set closer to the left end of the voltage array.

[0034] Alternatively, if the voltages in the voltage array are arranged in descending order, and the left end of the voltage array contains larger voltages while the right end contains smaller voltages, the preset position is set closer to the right end of the voltage array.

[0035] Furthermore, the first and second preset times can be set according to actual needs. For example, but not limited to, the second preset time can be set to 1-3 days, and the first preset time can be set to 30 days, etc. There are no restrictions here.

[0036] In this way, the faulty battery string can be identified based on its position before and after the voltage reaches the preset position. By taking into account the situation before and after the voltage reaches the preset position, a comprehensive analysis is conducted, reducing the probability of misjudgment and thus improving the accuracy and effectiveness of detection.

[0037] Optionally, in this embodiment of the invention, determining the faulty battery string based on its position before the voltage reaches a preset position and its position after the voltage reaches the preset position includes:

[0038] The voltage array at which the voltage reaches a preset position is defined as the first voltage array;

[0039] In the X voltage arrays following the first voltage array, the k1 voltage arrays are determined to maintain the voltage at a preset position continuously;

[0040] The probability that the position of a voltage is within a preset range in the Y voltage arrays preceding the first voltage array is k2.

[0041] The battery string corresponding to this voltage is identified as the faulty battery string;

[0042] Where k1, X and Y are all positive integers, k1 is greater than X / 2 and less than or equal to X, k2∈[0,0.3], and the preset position is within the preset range.

[0043] In other words, when the voltages in the voltage array are arranged in ascending order, with smaller voltages at the left end and larger voltages at the right end, and the default position is set to be closer to the left end of the voltage array, for the voltage of a certain battery string:

[0044] In the X voltage arrays following the first voltage array, more than half of the voltage arrays have the voltage position remaining in a low position, indicating that the voltage of the battery string is low and this low voltage has been maintained for a long time.

[0045] In the Y voltage arrays preceding the first voltage array, the probability of the voltage's position being within the preset range is relatively small, meaning the voltage's position is relatively high. In other words, the voltage value is relatively large, indicating that the battery string previously had a higher voltage, which in turn indicates that the voltage of the battery string decreased sharply within the second preset time period.

[0046] Specifically, in the embodiments of the present invention, the values ​​of X and Y can be set according to actual needs, such as, but not limited to, X being set to 180 and Y being set to 1-3 charging times (where the charging time refers to the time from the start of this charging to the start of the next charging), etc., and are not limited here.

[0047] Similarly, the values ​​of k1 and k2 can be set according to actual needs. For example, but not limited to, k1 can also be set to be greater than two-thirds of X and less than or equal to X, and k2 can be set to k2∈[0,0.4], etc., which are not limited here.

[0048] Specifically, this sharp drop in voltage may be caused by the following reasons:

[0049] 1. A sudden internal or external short circuit occurs in the battery string;

[0050] Internal short circuit refers to a short circuit occurring inside a single cell; external short circuit refers to a short circuit occurring between single cells.

[0051] 2. Abnormal degradation occurred in the cells within the individual battery.

[0052] 3. As the battery pack is used in a cycle of charging and discharging, the self-discharge rate gradually increases.

[0053] Optionally, in this embodiment of the invention, when the voltages in the voltage array are arranged in ascending order, the preset position is the first position, and the preset range is from the first to the fifth position;

[0054] When the voltages in the voltage array are arranged in descending order, the default position is the last one, and the default range is from the fifth from the end to the last one.

[0055] Of course, the preset position is not limited to the first or the last position. It can also be the second or the second to last position, or the third or the third to last position. Similarly, the preset range is not limited to the first to the fifth position or the fifth to the last position. It can also be the first to the fourth position or the fourth to the last position, or the first to the sixth position or the sixth to the last position.

[0056] In other words, the preset position and preset range can be set according to actual needs, and are not limited here.

[0057] For example, suppose a battery pack contains 96 battery strings connected in series (in reality, it is not limited to 96, but is used as an example here). Each battery string contains three individual cells connected in parallel (in reality, it is not limited to three, but is used as an example here). Suppose that the voltage of battery string numbered 60# drops sharply to 1 in the voltage array within 1-3 days (i.e., from September 5th to September 7th, 2020), and remains at 1 for nearly a month after dropping to 1. The probability of its position being in [1,5] during the 1-3 charging periods before dropping to 1 (e.g., from September 4th to September 7th, 2020) is less than 30%. Figure 3 As shown, it can be determined at this point that the battery string numbered 60# has malfunctioned;

[0058] Furthermore, to verify the above conclusion, after disassembling the battery string numbered 60#, it was found that one of the individual cells had electrode wrinkles (such as...). Figure 4 (As shown in the dashed circle in the image), this leads to an internal short circuit problem.

[0059] For example, the voltage position of battery string number 38 in the voltage array dropped sharply to 1 within 1-3 days (around September 2, 2020), and remained at position 1 for the next two weeks. The probability of its position being in the range [1, 5] during the 1-3 charging periods before dropping to 1 was less than 30%. Figure 5 As shown, it can be determined at this point that the battery string numbered 60# has malfunctioned;

[0060] Furthermore, to verify the above conclusion, after disassembling the battery string numbered 38#, it was found that one of the individual cells had electrode wrinkles (such as...). Figure 6 The problem of internal short circuit was caused by the dashed circle in Figure (a). Another individual cell had minor electrode scratches (such as...). Figure 6 (As shown within the dashed circle in Figure (b)).

[0061] Optionally, in this embodiment of the invention, in the Y voltage arrays prior to determining the first voltage array, the probability that the position of the voltage falls within a preset range is k2 or later, and before determining the battery string corresponding to the voltage as a faulty battery string, the method further includes:

[0062] If the voltages in any voltage array are arranged in ascending order, then in the voltage arrays following the first voltage array, the position of that voltage shows a decreasing trend.

[0063] Alternatively, the voltages in any voltage array are arranged in descending order, and the position of the voltage in the voltage arrays after the first voltage array shows an upward trend.

[0064] In other words, taking the voltages in the voltage array arranged in ascending order as an example, after the position of the voltage in the battery string decreases, the position of that voltage generally shows a downward trend, that is, it remains in a low position, which further indicates that the battery string corresponding to that voltage has failed. This can reduce misjudgments and improve the accuracy of the judgment results.

[0065] In specific implementation, in this embodiment of the invention, the determination of the number N of voltage arrays can include the following cases:

[0066] Case 1: N = M.

[0067] Optionally, in this embodiment of the invention, N voltage arrays arranged in chronological order of acquisition time are determined, specifically including:

[0068] Each voltage collected in each acquisition cycle is combined into a first data point, and the first data points are arranged in chronological order of acquisition time.

[0069] Sort the voltages in the first data according to their size to obtain a voltage array.

[0070] For example, taking a battery pack containing three battery strings as an example, three voltages are collected when the first collection cycle is reached. These three voltages are combined into the first data, and the three voltages are sorted in order of size to obtain the corresponding voltage array.

[0071] When the second acquisition cycle arrives, three voltages are also acquired. These three voltages are combined to form the second set of first data, and the three voltages are sorted in order of size to obtain the corresponding voltage array.

[0072] Similarly, three voltages are collected in each acquisition cycle to form the corresponding first data. The three voltages included in each first data are sorted in order of size to obtain the corresponding voltage array.

[0073] One point to note is that the voltages in each of the first data items can be sorted either in descending order or in ascending order.

[0074] Therefore, during the first preset time, which includes M acquisition cycles, a total of M first data points are obtained. Each first data point is arranged in chronological order of acquisition time, so the corresponding voltage arrays are also arranged in chronological order of acquisition time, resulting in a total of M voltage arrays.

[0075] Specifically, in case 1, each voltage in the first data set can be sorted in order of magnitude upon obtaining the first data set to obtain the corresponding voltage array, as in the example above; or, after obtaining all the first data sets, the voltages in each first data set can be sorted separately to obtain the voltage arrays; either method is acceptable, and the choice can be made according to actual needs during implementation, and is not limited here.

[0076] Case 2: N <M。

[0077] Optionally, in this embodiment of the invention, N voltage arrays arranged in chronological order of acquisition time are determined, including:

[0078] Each voltage collected in each acquisition cycle is combined into a first data point, and the first data points are arranged in chronological order of acquisition time.

[0079] Using A consecutive first data points as a fixed length, a moving average filter is applied to each first data point to obtain N second data points arranged in chronological order of collection time. The second data points include the average voltage of each battery string, which is determined based on A voltages corresponding to each battery string, where A is an integer greater than 1.

[0080] The average voltage values ​​in the second set of data are sorted in ascending order to obtain a voltage array.

[0081] Thus, by using moving average filtering, disturbances from abnormal voltages can be avoided, making the data more stable and reliable, thereby improving the accuracy of subsequent fault diagnosis.

[0082] Optionally, in this embodiment of the invention, using A consecutive first data points as a fixed length, a moving average filtering process is performed on each first data point, including:

[0083] Consider A consecutive first data points as a queue;

[0084] For the first data point to the Ath data point collected: take the queue containing the first data point to the Ath data point as the current queue, calculate the average voltage of the A voltages corresponding to each battery string in the current queue, and the average voltage of each battery string constitutes the first data point.

[0085] For each of the first data points from the second to the last, the following procedure is executed:

[0086] Determine the current queue;

[0087] Remove the first element from the current queue and move the remaining elements to the front in the current queue.

[0088] The latest collected first data is added to the current queue as the tail of the queue to form the updated current queue. The average voltage of A corresponding voltages for each battery string in the updated current queue is calculated.

[0089] The updated average voltage values ​​in the current queue constitute a second set of data.

[0090] For example, taking a battery pack containing 3 battery strings, with A = 30 and M = 40, a total of 40 first data points can be obtained, and these 40 first data points are arranged in chronological order of collection time; the specific process of moving average filtering includes:

[0091] When the 30 consecutive first data points are regarded as a queue, the first queue includes the first data point to the thirtieth data point. Since each data point includes the voltage of three battery strings, the average of the 30 voltages of each battery string can be calculated to obtain the average voltage of each battery string, that is, a total of three average voltages are obtained. Then, these three average voltages are used as the second data points, and the three average voltages are sorted to obtain the first voltage array.

[0092] Next, remove the first data from the first queue, move the second to thirtieth data forward in sequence, and add the thirty-first data as the tail of the queue to form the second queue. Calculate the average of the 30 voltages of each battery string to obtain the average voltage of each battery string, that is, obtain a total of three average voltages. Then, use these three average voltages as the second data and sort them to obtain the second voltage array.

[0093] Next, remove the second first data from the second queue, move the third to the thirty-first first data forward in sequence, and add the thirty-second first data as the tail of the queue to form the third queue. Calculate the average of the 30 voltages of each battery string to obtain the average voltage of each battery string, that is, obtain a total of three average voltages. Then, use these three average voltages as the second data and sort them to obtain the third voltage array.

[0094] Similarly, the above process is performed on the remaining first data in sequence to obtain the fourth voltage value to the eleventh voltage array. Therefore, N is 11 at this time. Since M is 40, N is less than M.

[0095] In summary, in practical implementation, either scenario 1 or scenario 2 can be used to determine each voltage array according to actual needs, and there is no limitation here.

[0096] Optionally, in embodiments of the present invention, it further includes:

[0097] If multiple voltages of the same battery string are collected in any acquisition cycle, and the voltages of the multiple battery strings are the same, then any one of the voltages of the multiple battery strings will be taken as the voltage of that battery string in that acquisition cycle.

[0098] This is because:

[0099] Ideally, when acquiring the voltage of a battery string in a certain acquisition cycle, only one voltage should be acquired. However, in actual voltage acquisition, abnormal situations may occur, resulting in multiple voltages being acquired in a certain acquisition cycle for a particular battery string. In such cases, duplicate voltages need to be removed to avoid errors in determining the voltage array, improve the accuracy of voltage array determination, and thus improve the accuracy of faulty battery detection.

[0100] Based on the same inventive concept, this invention provides a detection device for faulty batteries in a battery pack. The implementation principle of this detection device is similar to that of the aforementioned detection method. For the specific implementation of this detection device, please refer to the specific embodiments of the aforementioned detection method. Repeated details will not be repeated.

[0101] Specifically, embodiments of the present invention provide a device for detecting faulty batteries in a battery pack, such as... Figure 7 As shown, it may include:

[0102] Memory 701 is used to store program instructions;

[0103] The processor 702 is used to call the program instructions stored in the memory 701 and execute the detection method described above as provided in the embodiments of the present invention according to the obtained program.

[0104] Based on the same inventive concept, embodiments of the present invention provide an electric device, such as... Figure 8 As shown, it may include: the detection device 801 provided in the embodiments of the present invention.

[0105] Of course, in specific implementations, electric equipment may include not only detection devices, but also other structures used to realize the functions of electric equipment, which will not be described in detail here.

[0106] Optionally, in embodiments of the present invention, the electric device may be, but is not limited to, an electric vehicle.

[0107] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for detecting faulty batteries in a battery pack, characterized in that, The battery pack includes multiple battery strings connected in series, each battery string including at least one individual cell, and when the battery string includes multiple individual cells, the multiple individual cells are connected in parallel; the detection method includes: Within a first preset time period, the voltage of each battery string is collected according to a preset collection cycle, and N voltage arrays are determined in chronological order of collection time; wherein each voltage array includes the voltage of each battery string after being sorted in size order; when the first preset time period includes M collection cycles, M is a positive integer not less than N; The voltage position is determined to reach a preset position within a second preset time; wherein the second preset time is less than the first preset time; the preset position is set near the end of the voltage array with the lowest voltage. The voltage array in which the voltage reaches the preset position in the voltage array is defined as the first voltage array; In determining k1 of the X voltage arrays following the first voltage array, the voltage is continuously maintained at the preset position; The probability that the position of a voltage in the Y voltage arrays preceding the first voltage array falls within a preset range is k2; The battery string corresponding to the voltage is identified as the faulty battery string; After determining the first voltage array, in the Y voltage arrays prior to that determination, the probability that the position of the voltage falls within a preset range is k2, and before determining the battery string corresponding to that voltage as a faulty battery string, the process further includes: If the voltages in any of the voltage arrays are arranged in ascending order, then in the voltage arrays following the first voltage array, the position of the voltage shows a decreasing trend. Alternatively, the voltages in any of the voltage arrays are arranged in descending order, and it is determined that the position of the voltage in the voltage arrays following the first voltage array shows an upward trend; Where k1, X and Y are all positive integers, k1 is greater than X / 2 and less than or equal to X, k2∈[0,0.3], and the preset position is within the preset range.

2. The detection method as described in claim 1, characterized in that, When the voltages in the voltage array are arranged in ascending order, the preset position is the first position, and the preset range is from the first to the fifth position. When the voltages in the voltage array are arranged in descending order, the preset position is the last one, and the preset range is from the fifth from the end to the last one.

3. The detection method as described in claim 1, characterized in that, N voltage arrays were determined in chronological order of acquisition time, including: Each voltage collected in each acquisition cycle is combined into a first data point, and the first data points are arranged in chronological order of acquisition time. Using A consecutive first data points as a fixed length, a moving average filter is applied to each first data point to obtain N second data points arranged in chronological order of collection time; wherein, the second data points include the average voltage of each battery string, the average voltage being determined based on A voltages corresponding to each battery string; A is an integer greater than 1; The average voltage values ​​in the second data are sorted in ascending order to obtain the voltage array.

4. The detection method as described in claim 3, characterized in that, Using A consecutive first data points as a fixed length, perform moving average filtering on each of the first data points, including: Treat A consecutive A first data points as a queue; For the first data to the Ath data collected: take the queue including the first data to the Ath data as the current queue, calculate the average voltage of the A voltages corresponding to each battery string in the current queue, and the average voltage of each battery string constitutes the first data. For each of the second to the last piece of first data, the following process is performed: Determine the current queue; Remove the first piece of data from the current queue, and move the remaining pieces of data in the current queue forward in sequence; The latest collected first data is added to the current queue as the tail of the queue to form an updated current queue. The average voltage of A voltages corresponding to each battery string in the updated current queue is calculated. The average voltage values ​​in the updated current queue constitute a second set of data.

5. The detection method as described in claim 1, characterized in that, Also includes: If multiple voltages of the same battery string are collected in any one of the acquisition cycles, and the voltages of the multiple battery strings are the same, then any one of the voltages of the multiple battery strings shall be taken as the voltage of the battery string in that acquisition cycle.

6. A device for detecting faulty batteries in a battery pack, characterized in that, include: Memory, used to store program instructions; A processor is configured to invoke the program instructions stored in the memory and execute the detection method as described in any one of claims 1-5 according to the obtained program.

7. An electric device, characterized in that, include: The device for detecting faulty batteries in a battery pack as described in claim 6.

Images