Battery pack short circuit evaluation method, system, device, medium and product

Abstract

The invention relates to the technical field of battery fault detection, in particular to a battery pack short-circuit evaluation method, system and device, a medium and a product. According to charging voltage curve segments, obtained in real time, of all single batteries in a battery pack, a mid-value end voltage curve of the battery pack is determined to serve as a reference standard; by determining the Hausdorff distance between the charging voltage curve segment and the median end voltage curve of each battery monomer, the Hausdorff distance is utilized to evaluate the condition of early internal short circuit of the battery monomer, so that the short-circuit battery monomer is detected by utilizing the Hausdorff distance, the accuracy and the reliability of short circuit detection are ensured, and meanwhile, the accuracy and the reliability of short circuit detection are improved. A complete charging voltage curve is not needed, so that the method is still effective when the battery cannot be fully charged and discharged, the calculation complexity is reduced, and the applicability of short circuit evaluation is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of battery fault detection, and in particular, to a method, system, device, medium and product for evaluating the short - circuit of a battery pack. Background Art

[0002] Due to the advantages of high power density, low self - discharge rate, long cycle life and no memory effect, lithium - ion batteries are widely used in fields such as electric vehicles and grid energy storage. However, lithium - ion batteries have potential safety problems, especially accidents characterized by thermal runaway occur from time to time, which has caused public concerns about the safety of lithium - ion batteries. In the past few years, analysis reports of battery pack spontaneous combustion accidents from different research institutions have shown that internal short - circuit is one of the main reasons for the thermal runaway of lithium - ion batteries. Before the internal short - circuit deteriorates into thermal runaway, there is usually a long evolution and development process. In the early stage of internal short - circuit, the equivalent short - circuit resistance is relatively large, and the changes in battery electro - thermal parameters caused by the short - circuit are not obvious, with strong concealment. This also makes it difficult to detect early internal short - circuit faults. Therefore, timely diagnosis of early internal short - circuit faults is a crucial and challenging task for ensuring the safe and stable operation of lithium - ion batteries.

[0003] Existing diagnostic methods for early internal short - circuit of battery packs all require a complete charging voltage curve during the diagnostic implementation process. However, during actual operation, affected by users' charging habits, lithium - ion batteries may not experience full charge and full discharge. In other words, the initial state of charge (SOC) of battery charging may not be 0%. At this time, it is difficult to obtain a complete charging voltage curve, which will lead to poor effectiveness and reliability of the early internal short - circuit diagnosis of the battery pack, limit the applicability of the diagnostic method, and the computational complexity is also relatively high. Summary of the Invention

[0004] In view of this, the present invention provides a method, system, device, medium and product for evaluating the short - circuit of a battery pack, which solves the technical problems of poor effectiveness and reliability of the early internal short - circuit diagnosis of the battery pack, limiting the applicability of the diagnostic method, and relatively high computational complexity.

[0005] In the first aspect of the present invention, a method for evaluating the short - circuit of a battery pack is provided, including:

[0006] Determining the median terminal voltage curve of the battery pack according to the charging voltage curve segments of each battery cell in the battery pack obtained in real - time; wherein, the median terminal voltage curve is obtained by sorting the terminal voltages of each battery cell at any moment within the charging voltage curve segments.

[0007] Determine the Hausdorff distance between the charging voltage curve segments of each of the battery cells and the median terminal voltage curve;

[0008] In the case where it is determined that the Hausdorff distance is greater than a preset distance threshold, it is determined that the battery cell corresponding to the Hausdorff distance has an early internal short circuit.

[0009] Preferably, the determining the median terminal voltage curve of the battery pack according to the charging voltage curve segments of each battery cell in the battery pack obtained in real time includes:

[0010] According to the charging voltage curve segments of each of the battery cells in the battery pack obtained in real time, take the average value of the terminal voltages of each of the battery cells at each moment to obtain the median value of the terminal voltages of each of the battery cells at each moment;

[0011] Sort the median values of the terminal voltages of each of the battery cells at each moment according to the time sequence to determine the median terminal voltage curve.

[0012] Preferably, the method further includes:

[0013] Perform a normalization operation on the median terminal voltage curve and the charging voltage curve segments of each of the battery cells.

[0014] Preferably, the method further includes:

[0015] Perform a moving average filtering operation on the median terminal voltage curve and the charging voltage curve segments of each of the battery cells.

[0016] Preferably, the method further includes:

[0017] In the case where it is determined that the Hausdorff distance is not greater than the preset distance threshold, it is determined that the battery cell corresponding to the Hausdorff distance has not had an early internal short circuit.

[0018] Preferably, the method further includes:

[0019] For each short-circuited battery cell, determine the charging power of the short-circuited battery cell according to the charging current and the short-circuit charging period of the charging voltage curve segment of the short-circuited battery cell; wherein, the short-circuited battery cell is the battery cell determined to have an early internal short circuit;

[0020] For each normal battery cell, determine the charging power of the normal battery cell according to the charging current and the normal charging period of the charging voltage curve segment of the normal battery cell; wherein, the normal battery cell is the battery cell determined not to have an early internal short circuit;

[0021] Determine the short-circuit current of the short-circuited battery cell within the charging voltage curve segment based on the charging power of the short-circuited battery cell, the charging power of the normal battery cell, and the short-circuit charging cycle;

[0022] Determine the short-circuit resistance of the short-circuited battery cell within the charging voltage curve segment based on the short-circuit current and the average value of the charging voltage of the short-circuited battery cell within the charging voltage curve segment;

[0023] Evaluate the severity of the internal short circuit of the short-circuited battery cell based on the short-circuit resistance.

[0024] In a second aspect, the present invention provides a battery pack short-circuit evaluation system, including:

[0025] A median voltage determination module, configured to determine the median terminal voltage curve of the battery pack according to the charging voltage curve segments of each battery cell in the battery pack obtained in real time; wherein, the median terminal voltage curve is obtained by sorting the terminal voltages of each battery cell at any moment within the charging voltage curve segment;

[0026] A distance determination module, configured to determine the Hausdorff distance between the charging voltage curve segment of each battery cell and the median terminal voltage curve;

[0027] A short-circuit evaluation module, configured to determine that the battery cell corresponding to the Hausdorff distance has an early internal short circuit if it is determined that the Hausdorff distance is greater than a preset distance threshold.

[0028] In a third aspect, the present invention provides an electronic device, which includes a memory and a processor. When a computer program stored in the memory is executed by the processor, the processor is caused to execute the steps of the battery pack short-circuit evaluation method described in the first aspect.

[0029] In a fourth aspect, the present invention provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed, the steps of the battery pack short-circuit evaluation method described in the first aspect are implemented.

[0030] In a fifth aspect, the present invention provides a computer program product, which includes a computer program stored on a non-transitory computer-readable storage medium. The computer program includes program instructions. When the program instructions are executed by a computer, the computer is caused to execute the steps of the battery pack short-circuit evaluation method described in the first aspect.

[0031] As can be seen from the above technical solutions, the present invention determines the median terminal voltage curve of the battery pack as a reference standard by obtaining the charging voltage curve segments of each battery cell in the battery pack in real time. By determining the Hausdorff distance between the charging voltage curve segment of each battery cell and the median terminal voltage curve, the Hausdorff distance is used to evaluate the occurrence of early internal short circuit in the battery cell, so as to detect the short-circuited single battery using the Hausdorff distance, ensuring the accuracy and reliability of short-circuit detection. At the same time, a complete charging voltage curve is not required, which makes the method of the present invention still effective when the battery cannot be fully charged and discharged, reduces the computational complexity, and improves the applicability of short-circuit evaluation. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0033] Figure 1 It is an application environment diagram of a battery pack short-circuit evaluation method provided by an embodiment of the present invention;

[0034] Figure 2 It is a flowchart of a battery pack short-circuit evaluation method provided by an embodiment of the present invention;

[0035] Figure 3 It is a schematic diagram of short-circuit resistance estimation provided by an embodiment of the present invention;

[0036] Figure 4 It is a schematic diagram of the Hausdorff distance of each single battery when no short circuit occurs in Cycle 1 provided by an embodiment of the present invention;

[0037] Figure 5 It is a schematic diagram of the Hausdorff distance of each single battery when the short-circuit resistance is 300 Ω in Cycle 2 provided by an embodiment of the present invention;

[0038] Figure 6 It is a schematic diagram of the Hausdorff distance of each single battery when the short-circuit resistance is 200 Ω in Cycle 3 provided by an embodiment of the present invention;

[0039] Figure 7 It is a schematic diagram of the Hausdorff distance of each single battery when the short-circuit resistance is 100 Ω in Cycle 4 provided by an embodiment of the present invention;

[0040] Figure 8 It is a schematic diagram of the Hausdorff distance of each single battery when the short-circuit resistance is 50 Ω in Cycle 5 provided by an embodiment of the present invention;

[0041] Figure 9 Schematic diagram of the Hausdorff distance of each single battery when the short - circuit resistance of cycle 6 is 10 Ω provided by the embodiment of the present invention;

[0042] Figure 10 Schematic diagram of the Hausdorff distance of each single battery when the short - circuit resistance of cycle 7 is 5 Ω provided by the embodiment of the present invention;

[0043] Figure 11 Schematic diagram of the structure of a battery pack short - circuit evaluation system provided by the embodiment of the present invention;

[0044] Figure 12 Schematic diagram of the structure of an electronic device provided by the embodiment of the present invention. Detailed implementation manners

[0045] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0046] The battery pack short - circuit evaluation method provided by the embodiments of the present application can be applied to an application environment as Figure 1 shown. Among them, the terminal 101 communicates with the server 102 through the network. The data storage system can store the data that the server 102 needs to process. The data storage system can be integrated on the server 102, or can be placed in the cloud or other network servers. The terminal 101 or the server 102 determines the median terminal voltage curve of the battery pack according to the charging voltage curve segments of each battery cell in the battery pack obtained in real - time; among them, the median terminal voltage curve is obtained by sorting the terminal voltages of each battery cell at any moment within the charging voltage curve segment; determines the Hausdorff distance between the charging voltage curve segment of each battery cell and the median terminal voltage curve; and in the case of determining that the Hausdorff distance is greater than a preset distance threshold, it is determined that the battery cell corresponding to the Hausdorff distance has an early internal short - circuit.

[0047] The terminal 101 can be, but is not limited to, various personal computers, laptop computers, smart phones, tablet computers, etc.

[0048] The server 102 can be an independent physical server, or a server cluster or distributed system composed of multiple physical servers, or a cloud server providing cloud computing services.

[0049] Such as Figure 2As shown in the figure, an embodiment of the present application provides a method for evaluating the short - circuit of a battery pack. Taking the application of this method to the Figure 1 terminal 101 or server 102 in it as an example for illustration, it includes the following steps S1 to S3. Among them:

[0050] Step S1: Determine the median terminal voltage curve of the battery pack according to the charging voltage curve segments of each battery cell in the battery pack obtained in real time; among them, the median terminal voltage curve is obtained by sorting the terminal voltages of each battery cell at any moment within the charging voltage curve segment.

[0051] Among them, the charging voltage curve segment can be an incomplete charging voltage curve. Among them, the complete charging curve refers to the curve in the range of state of charge from 0% to 100%, that is, the voltage curve during the process of charging the battery from the fully discharged state to the fully charged state. And the incomplete charging voltage curve refers to the charging voltage curve in any state - of - charge interval. The incomplete charging voltage curve does not require a long charging process, only fragment data, and is easier to obtain in an actual energy storage system.

[0052] Considering that the median is not affected by extreme values, at any moment, the terminal voltages among the individual cells in the lithium - ion battery pack are sorted to obtain the median terminal voltage curve, which is used as a reference standard to represent the state of normal cells in the battery pack.

[0053] Among them, at each moment, the average value of the terminal voltages of all batteries is taken to obtain the voltage median of the battery pack at the current moment. The voltage median obtained in this way over time can form the median terminal voltage curve, without considering the voltage interval, and only the voltage values are statistically averaged at each moment.

[0054] Step S2: Determine the Hausdorff distance between the charging voltage curve segment of each battery cell and the median terminal voltage curve.

[0055] Among them, in the embodiment of the present application, the Hausdorff distance is used to measure the similarity between the charging voltage curve segment of each battery cell and the median terminal voltage curve, and further detect the short - circuited single - cell battery in the battery pack.

[0056] The Hausdorff distance, also often referred to as the Pompeiu–Hausdorff metric, can calculate the distance between two non - empty finite subsets in the same space.

[0057] Specifically, in the present invention, the numerical values of the charging voltage curve segments of each battery cell of the single - cell battery and the median terminal voltage curve are respectively represented as V med and V:

[0058]

[0059]

[0060] Among them, N represents the data length. The Hausdorff distance between them is defined as the maximum distance from any element in V med to any element in V, as shown in the following formula:

[0061]

[0062]

[0063] Among them, d H (V med , V) represents the Hausdorff distance from V med to V. ǁ ǁ represents any basic norm on V med and V, such as the L2 norm or the Euclidean norm, etc. h(V med , V) represents the directed Hausdorff distance from V med to V, which determines the element V med in V that is farthest from V, V med (i), and calculates the distance from this element V med (i) to the nearest element in V using the given norm. Specifically, h(V med , V) is actually the maximum distance in the output sequence after sorting the distances from each point in V med to the nearest point in the V set. d H (V med , V) represents the maximum return value of two directed Hausdorff distances, which quantitatively calculates the degree of difference between two curves.

[0064] Step S3: If it is determined that the Hausdorff distance is greater than a preset distance threshold, it is determined that the battery cell corresponding to the Hausdorff distance has an early internal short circuit.

[0065] Among them, based on the calculation process of the Hausdorff distance, the Hausdorff distances corresponding to all the battery cells in the battery pack can be calculated. The battery cells with a Hausdorff distance greater than the preset distance threshold are detected as having an early internal short circuit. On the contrary, if it is determined that the Hausdorff distance is not greater than the preset distance threshold, it is determined that the battery cell corresponding to the Hausdorff distance has not had an early internal short circuit, that is, a normal single battery cell.

[0066] Among them, early internal short circuit refers to the phenomenon that during the charge and discharge process of a battery cell, due to reasons such as internal material aging, structural changes, or manufacturing process defects, a tiny conductive channel appears inside the battery, thereby causing an internal short circuit of the battery. Early internal short circuit is usually not easily detected directly, but it will lead to problems such as a decline in battery performance, an increase in temperature, and even trigger safety issues such as battery thermal runaway. Through the battery pack short circuit evaluation method provided by the present invention, it is possible to timely detect the battery cells with early internal short circuit before the battery suffers a serious failure, thereby taking effective maintenance and management measures to avoid the occurrence of safety accidents and improve the reliability and safety of the battery pack.

[0067] Among them, the distance threshold is usually a fixed parameter value.

[0068] It should be noted that in the embodiments of the present application, by determining the median terminal voltage curve of the battery pack as a reference standard according to the charging voltage curve segments of each battery cell in the battery pack obtained in real time, and by determining the Hausdorff distance between the charging voltage curve segment of each battery cell and the median terminal voltage curve, the Hausdorff distance is used to evaluate the situation of early internal short circuit of the battery cell, so as to detect the short-circuited single battery using the Hausdorff distance, ensuring the accuracy and reliability of the short circuit detection. At the same time, a complete charging voltage curve is not required, which makes the method of the present invention still effective when the battery cannot be fully charged and discharged, reduces the computational complexity, and improves the applicability of the short circuit evaluation.

[0069] In some embodiments, determining the median terminal voltage curve of the battery pack according to the charging voltage curve segments of each battery cell in the battery pack obtained in real time includes:

[0070] Step S101: According to the charging voltage curve segments of each battery cell in the battery pack obtained in real time, take the average value of the terminal voltages of each battery cell at each moment to obtain the median terminal voltage of each battery cell at each moment.

[0071] Step S102: Sort the median terminal voltages of each battery cell at each moment in chronological order to determine the median terminal voltage curve.

[0072] In some embodiments, in order to amplify the abnormal voltage change caused by the early internal short circuit fault for convenient fault detection, this method further includes:

[0073] Perform a normalization operation on the median terminal voltage curve and the charging voltage curve segments of each battery cell.

[0074] Among them, due to the relatively large equivalent short-circuit resistance and small short-circuit current, early internal short circuits do not cause obvious abnormal changes in the battery voltage. To facilitate fault detection, it is necessary to amplify the voltage difference between the short-circuited single battery and the normal single battery caused by early internal short circuits through normalization operations. Specifically, in the present invention, the obtained median voltage curve and the voltage curves of each single battery are combined for normalization. Assuming that the battery pack is composed of n battery monomers connected in series, together with the median voltage curve, a total of n + 1 voltage curves can be obtained. The normalization value of the jth voltage curve at time ti is as follows:

[0075]

[0076] Among them, U j (t i ) is the value of the jth voltage curve at t i moment, where j = [1, 2,..., n + 1]. U mean (t i ) is the average value of all voltage curves at t i moment. U max (t i ) and U min (t i ) are the maximum and minimum values of the jth voltage curve at t i moment respectively. Note that the normalization value is dimensionless.

[0077] Compared with normal single battery cells, the voltage of the single battery cell with an internal short circuit will gradually decrease. At this time, U min (t i ) in the formula is the voltage of the short-circuited single battery cell. Therefore, for the short-circuited single battery cell, the denominator in the formula continuously increases and the numerator continuously decreases, and its voltage normalization value will continuously decrease. On the contrary, the normalization value of the normal single battery cell will increase slowly. It can be seen that through the above normalization operation, the voltage difference between the short-circuited single battery cell and the normal single battery cell can be amplified, thereby facilitating fault detection.

[0078] Considering that the voltage value after normalization is easily contaminated by sensor measurement noise, a moving average filter is used to smooth it to suppress the interference of sensor measurement noise on fault detection. Specifically, this method further includes:

[0079] Performing a moving average filtering operation on the median terminal voltage curve and the charging voltage curve segments of each battery single cell.

[0080] Among them, the normalized value of the above voltage is vulnerable to measurement noise. Therefore, it is necessary to adopt a suitable filter to obtain a smooth normalized voltage curve. The present invention uses moving average filtering to smooth the normalized voltage curve. Moving average filtering smooths the signal by calculating the average value of the signal within a preset window. Given the normalized voltage signal Z contaminated by noise, the moving average filter can be designed as:

[0081]

[0082] Among them, Z r represents the value of the normalized voltage signal Z at the r-th moment, is the corresponding value after filtering, 2N p is the window size of the sliding filter and N p is an integer, l is the number of time lags, and Z r-l is the value of the normalized voltage signal at the (r - l)-th moment.

[0083] In some embodiments, after detecting a short-circuited single battery in the battery pack, the embodiments of the present application further estimate its short-circuit current and short-circuit resistance to quantitatively evaluate the severity and evolution stage of the short circuit. Among them, the charging voltage curve segment of the short-circuited battery cell and the incomplete charging voltage curve of the normal single battery are compared horizontally, and its short-circuit current and short-circuit resistance are calculated to quantitatively evaluate the severity of its short-circuit fault.

[0084] Specifically, the method further includes:

[0085] Step S401: For each short-circuited battery cell, determine the charging power of the short-circuited battery cell according to the charging current and short-circuit charging cycle of the charging voltage curve segment of the short-circuited battery cell; among them, the short-circuited battery cell is a battery cell determined to have an early internal short circuit;

[0086] Step S402: For each normal battery cell, determine the charging power of the normal battery cell according to the charging current and normal charging cycle of the charging voltage curve segment of the normal battery cell; among them, the normal battery cell is a battery cell determined not to have an early internal short circuit;

[0087] Step S403: Determine the short-circuit current of the short-circuited battery cell within the charging voltage curve segment according to the charging power of the short-circuited battery cell, the charging power of the normal battery cell, and the short-circuit charging cycle;

[0088] Step S404: Determine the short-circuit resistance of the short-circuited battery cell within the charging voltage curve segment according to the short-circuit current and the average value of the charging voltage of the short-circuited battery cell within the charging voltage curve segment;

[0089] Step S405: Evaluate the severity of the internal short circuit of the short-circuited battery cell based on the short-circuit resistance.

[0090] Exemplarily, as Figure 3 shown, Figure 3 FIG. shows a schematic diagram of the complete constant-current charging voltage curves of a normal cell and a cell with an early internal short circuit in a series battery pack. The solid line represents the charging voltage of the normal cell, and the dashed line represents the charging voltage of the short-circuited cell. It can be seen that during the entire constant-current charging process, the equivalent short-circuit resistance continuously consumes the power of the short-circuited cell, which causes the charging voltage curve of the short-circuited cell to be lower than that of the normal cell.

[0091] During actual operation, affected by the user's usage habits, the battery pack may not experience full charge and discharge, that is, a complete charging voltage curve cannot be obtained. Assume that only a charging voltage segment is obtained, and the starting voltage of this voltage segment is U A , and the ending voltage is U B . For a normal cell, the moment corresponding to the voltage U A of the cell is denoted as t normal,A , and the moment corresponding to the voltage U B is denoted as t normal,B . The time period from t normal,A to t normal,B is the normal charging cycle.

[0092] For the short-circuited cell, the moment corresponding to the voltage U A is denoted as t isc,A , and the moment corresponding to the voltage U B is denoted as t isc,B . For a normal cell, its charging power Q A within the voltage segment [U B can be calculated as: normal

[0093]

[0094] A , U B , the charging power Q isc of the short-circuited cell can be calculated as:

[0095]

[0096] Since the short-circuit resistance continuously consumes the power of the short-circuited cell, within the same voltage segment [U A , U B , Q normal > Q isc ​​, the difference between the two can be regarded as the leakage power of the short-circuited single battery caused by the short-circuit current. Therefore, within the voltage segment [U A , U B , the short-circuit current I isc can be estimated as:

[0097]

[0098] Finally, since the voltage across the short-circuit resistance is equal to the terminal voltage of the short-circuited single battery, using Ohm's law, within the voltage segment [U A , U B , the short-circuit resistance R isc can be calculated as:

[0099]

[0100] Among them, represents the average value of the charging voltage of the short-circuited single battery within the voltage segment [U A , U B .

[0101] Based on the above process, the short-circuit current and short-circuit resistance of the short-circuited single battery can be calculated, and the severity of the early internal short-circuit can be quantitatively evaluated based on this: the smaller the short-circuit resistance and the larger the short-circuit current, the more serious the internal short-circuit.

[0102] Among them, in the embodiment of the present application, the incomplete charging voltage segment is used to calculate the leakage power of the short-circuited single battery, and then the short-circuit current and short-circuit resistance are estimated to quantitatively evaluate the severity of the short-circuit, which is applicable to the actual application scenario.

[0103] In order to verify the technical effects presented by the present invention, tests were carried out on a battery pack composed of 4 cylindrical lithium-ion battery monomers connected in series to verify the effectiveness of the technology. The specifications of the monomers are shown in Table 1.

[0104] Table 1 Lithium-ion battery specification parameters

[0105]

[0106] The battery pack was charged at a constant current of 0.5 C. When the maximum terminal voltage of a single cell reached the charging cut-off voltage of 4.2 V, the battery pack stopped charging to prevent overcharging of the single cell. Then, the battery pack was subjected to a dynamic stress test discharge. When the minimum terminal voltage of a single cell reached the discharge cut-off voltage of 2.75 V, the battery pack stopped discharging to prevent over-discharging of the single cell. A total of 7 charge-discharge cycles were performed on the battery pack.

[0107] The present invention adopts the method of paralleling an external resistor across the two ends of the battery to simulate the early internal short - circuit fault. This method can not only better control the triggering time and location of the early internal short - circuit, but also simulate the evolution process of the early internal short - circuit, with good controllability and repeatability.

[0108] Specifically, in order to simulate the evolution process of the early internal short - circuit, short - circuit resistors with different amplitudes and corresponding manual switches are connected in series and then paralleled across the two ends of the single cell 4. By closing different switches, short - circuit resistors with different amplitudes can be paralleled across the two ends of the battery to simulate the occurrence and evolution of the early internal short - circuit. The smaller the short - circuit resistor, the larger the short - circuit current, indicating a more severe short - circuit. The short - circuit resistors paralleled corresponding to each charge - discharge cycle are shown in Table 2.

[0109] Table 2 Short - circuit resistors corresponding to different charge - discharge cycles

[0110]

[0111] Next, the Hausdorff distance corresponding to each single cell is calculated and compared with a predetermined threshold to detect the short - circuited single - cell battery.

[0112] Specifically, for the battery pack used in the present invention, the fault detection threshold is set to 0.3. It should be noted that during the actual use process, the fault detection threshold can be flexibly adjusted according to the battery type, application scenario, etc. to improve the sensitivity of the fault detection algorithm. The Hausdorff distances of each single cell in the battery pack during different charge - discharge cycles are as Figures 4 to 10 shown, where the dashed line represents the threshold. From Figures 4 to 10 it can be observed that in the first cycle, the Hausdorff distances of all single cells are lower than the threshold, indicating that all single cells are in a normal state and no short - circuit occurs within the first cycle. Starting from the second cycle, the Hausdorff distance corresponding to single cell 4 exceeds the threshold. On the contrary, the Hausdorff distances of other single cells are always lower than the threshold, indicating that starting from the second cycle, single cell 4 has an early internal short - circuit fault, while other single cells are still in a normal state. In addition, it can also be observed that as the short - circuit resistor decreases, the Hausdorff distance of single cell 4 shows an increasing trend, indicating that as the short - circuit deteriorates, the Hausdorff distance of the short - circuited single - cell battery will gradually increase. The above diagnostic results are consistent with the aforementioned fault injection situation, indicating that the proposed method can accurately detect the short - circuited single - cell battery in the lithium - ion battery pack, proving the effectiveness of the proposed method.

[0113] After detecting a short-circuited single cell in the battery pack, the method proposed above is further used to estimate its short-circuit resistance to quantify the severity and evolution stage of the short circuit. The true value, estimated value, and relative error of the short-circuit resistance of the short-circuited single cell 4 are listed in Table 3. As shown in Table 3, for the short-circuited single cell 4, the maximum relative error of the short-circuit resistance estimation result is 4.19%, and the minimum relative error is 1.40%. In addition, it can also be found from Table 3 that as the true short-circuit resistance connected in parallel at both ends of the battery decreases, the relative error of the estimation result generally shows a decreasing trend. This is because as the short-circuit resistance decreases, the short-circuit current gradually increases, and the fault characteristics caused by the short circuit become more and more obvious. The above-mentioned estimation error of the short-circuit resistance is within an acceptable range, which proves the effectiveness of the short-circuit quantitative evaluation method proposed by the present invention.

[0114] Table 3 Estimation results of the short-circuit resistance of the short-circuited single cell 4

[0115]

[0116] Based on the same inventive concept, the embodiment of the present application also provides a battery pack short-circuit evaluation system for implementing the battery pack short-circuit evaluation method involved above.

[0117] The implementation solution provided by this system to solve the problem is similar to the implementation solution described in the above method. Therefore, the specific limitations in one or more embodiments of the battery pack short-circuit evaluation system provided below can refer to the limitations on the battery pack short-circuit evaluation method in the above text, and will not be repeated here.

[0118] As Figure 11 shown, the embodiment of the present application provides a battery pack short-circuit evaluation system, including:

[0119] A median voltage determination module 100, configured to determine the median terminal voltage curve of the battery pack according to the charging voltage curve segments of each battery cell in the battery pack obtained in real time; wherein, the median terminal voltage curve is obtained by sorting the terminal voltages of each battery cell at any moment within the charging voltage curve segment.

[0120] A distance determination module 200, configured to determine the Hausdorff distance between the charging voltage curve segment of each battery cell and the median terminal voltage curve.

[0121] A short-circuit evaluation module 300, configured to determine that the battery cell corresponding to the Hausdorff distance has an early internal short circuit when it is determined that the Hausdorff distance is greater than a preset distance threshold.

[0122] In some embodiments, the median voltage determination module 100 is configured to:

[0123] According to the charging voltage curve segments of each battery cell in the battery pack obtained in real time, the average value of the terminal voltage of each battery cell at each moment is taken to obtain the median terminal voltage of each battery cell at each moment;

[0124] Sort the median terminal voltages of each battery cell at each moment according to the time sequence to determine the median terminal voltage curve.

[0125] In some embodiments, the system further includes: a normalization module for performing a normalization operation on the median terminal voltage curve and the charging voltage curve segments of each battery cell.

[0126] In some embodiments, the system further includes: a filtering module for performing a moving average filtering operation on the median terminal voltage curve and the charging voltage curve segments of each battery cell.

[0127] In some embodiments, the system further includes: a short - circuit judgment module for determining that the battery cell corresponding to the Hausdorff distance has not experienced an early internal short - circuit when it is determined that the Hausdorff distance is not greater than a preset distance threshold.

[0128] In some embodiments, the system further includes: a short - circuit resistance determination module for:

[0129] For each short - circuit battery cell, determine the charging power of the short - circuit battery cell according to the charging current and the short - circuit charging period of the charging voltage curve segment of the short - circuit battery cell; wherein, the short - circuit battery cell is a battery cell determined to have experienced an early internal short - circuit;

[0130] For each normal battery cell, determine the charging power of the normal battery cell according to the charging current and the normal charging period of the charging voltage curve segment of the normal battery cell; wherein, the normal battery cell is a battery cell determined not to have experienced an early internal short - circuit;

[0131] According to the charging power of the short - circuit battery cell, the charging power of the normal battery cell, and the short - circuit charging period, determine the short - circuit current of the short - circuit battery cell within the charging voltage curve segment;

[0132] According to the short - circuit current and the average value of the charging voltage of the short - circuit battery cell within the charging voltage curve segment, determine the short - circuit resistance of the short - circuit battery cell within the charging voltage curve segment;

[0133] Evaluate the severity of the internal short - circuit of the short - circuit battery cell according to the short - circuit resistance.

[0134] As Figure 12As shown in the figure, an embodiment of the present application provides an electronic device. The electronic device 10 includes a memory 20 and a processor 30. A computer program is stored in the memory 20. When the computer program is executed by the processor 30, the processor 30 is caused to execute the steps of the battery pack short - circuit evaluation method in the above - mentioned embodiment.

[0135] An embodiment of the present application provides a computer - readable storage medium, on which a computer program is stored. When the computer program is executed, it implements the steps of the battery pack short - circuit evaluation method in the above - mentioned embodiment.

[0136] An embodiment of the present application provides a computer program product. The computer program product includes a computer program stored on a non - transitory computer - readable storage medium. The computer program includes program instructions. When the program instructions are executed by a computer, the computer is caused to execute the steps of the battery pack short - circuit evaluation method described in the above - mentioned embodiment.

[0137] Those skilled in the art can clearly understand that for the convenience and brevity of description, the specific working processes of the above - described system, electronic device, computer storage medium, and computer program product can refer to the corresponding processes in the foregoing method embodiments and will not be described herein again.

[0138] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above - mentioned drawings are used to distinguish similar objects and do not necessarily need to describe a specific order or sequence. It should be understood that such used data can be interchanged under appropriate circumstances so that the embodiments of the present invention described herein can be implemented in an order different from those illustrated or described herein. In addition, the terms "include" and "have" and any variations thereof are intended to cover non - exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products, or devices.

[0139] It should be understood that although the steps in the flowcharts involved in the above - mentioned embodiments are shown in sequence according to the arrows, these steps do not necessarily have to be executed in the order indicated by the arrows. Unless clearly stated herein, the execution of these steps has no strict order limitation, and these steps can be executed in other orders. Moreover, at least a part of the steps in the flowcharts involved in the above - mentioned embodiments may include multiple steps or multiple stages. These steps or stages do not necessarily have to be executed at the same moment, but can be executed at different moments. The execution order of these steps or stages does not necessarily have to be sequential, but can be executed alternately or in turn with at least a part of other steps or steps in other steps.

[0140] In several embodiments provided by the present invention, it should be understood that the disclosed systems, electronic devices, computer storage media, computer program products and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For example, the division of the units is only a logical function division. In actual implementation, there may be other division methods. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed couplings or direct couplings or communication connections to each other can be through some interfaces. The indirect couplings or communication connections of the devices or units can be in electrical, mechanical or other forms.

[0141] The units described as separate components may or may not be physically separated. The components displayed as units may or may not be physical units, that is, they can be located in one place, or they can be distributed to multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0142] In addition, in each embodiment of the present invention, the functional units can be integrated in a processing unit, or each unit can exist physically alone, or two or more units can be integrated in one unit. The above integrated units can be implemented in the form of hardware or in the form of software functional units.

[0143] If the above integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of this technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in each embodiment of the present invention. And the foregoing storage medium includes: USB flash drives, mobile hard disks, read-only memories (English full name: Read-Only Memory, English abbreviation: ROM), random access memories (English full name: Random Access Memory, English abbreviation: RAM), magnetic disks or optical disks and other various media that can store program codes.

[0144] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A method for evaluating a short circuit of a battery pack, characterized in that, Including: Determine the median terminal voltage curve of the battery pack according to the charging voltage curve segments of each battery cell in the battery pack obtained in real time; wherein, the median terminal voltage curve is obtained by sorting the terminal voltages of each battery cell at any moment within the charging voltage curve segments; Determine the Hausdorff distance between the charging voltage curve segments of each battery cell and the median terminal voltage curve; In the case where it is determined that the Hausdorff distance is greater than a preset distance threshold, it is determined that the battery cell corresponding to the Hausdorff distance has an early internal short circuit.

2. The battery pack short circuit evaluation method according to claim 1, wherein The determining the median terminal voltage curve of the battery pack according to the charging voltage curve segments of each battery cell in the battery pack obtained in real time includes: According to the charging voltage curve segments of each battery cell in the battery pack obtained in real time, take the average value of the terminal voltages of each battery cell at each moment to obtain the median value of the terminal voltages of each battery cell at each moment; Sort the median values of the terminal voltages of each battery cell at each moment according to the time sequence to determine the median terminal voltage curve.

3. The battery pack short circuit evaluation method according to claim 1, characterized in that It further includes: Perform a normalization operation on the median terminal voltage curve and the charging voltage curve segments of each battery cell.

4. The battery pack short-circuit evaluation method according to any one of claims 1 to 3, characterized in that It further includes: Perform a moving average filtering operation on the median terminal voltage curve and the charging voltage curve segments of each battery cell.

5. The battery pack short circuit evaluation method according to claim 1, characterized in that It further includes: In the case where it is determined that the Hausdorff distance is not greater than the preset distance threshold, it is determined that the battery cell corresponding to the Hausdorff distance has not had an early internal short circuit.

6. The battery pack short circuit evaluation method according to claim 1 or 5, characterized in that It further includes: For each short-circuited battery cell, determine the charging power of the short-circuited battery cell according to the charging current and the short-circuit charging cycle of the charging voltage curve segment of the short-circuited battery cell; wherein, the short-circuited battery cell is the battery cell determined to have an early internal short circuit; For each normal battery cell, determine the charging power of the normal battery cell according to the charging current and the normal charging cycle of the charging voltage curve segment of the normal battery cell; wherein, the normal battery cell is the battery cell determined not to have an early internal short circuit; According to the charging power of the short-circuited battery cell, the charging power of the normal battery cell, and the short-circuit charging cycle, determine the short-circuit current of the short-circuited battery cell within the charging voltage curve segment; According to the short-circuit current and the average value of the charging voltage of the short-circuited battery cell within the charging voltage curve segment, determine the short-circuit resistance of the short-circuited battery cell within the charging voltage curve segment; Evaluate the severity of the internal short circuit of the short-circuited battery cell according to the short-circuit resistance.

7. A battery pack short - circuit evaluation system, characterized in that, Including: A median voltage determination module, configured to determine the median terminal voltage curve of the battery pack according to the charging voltage curve segments of each battery cell in the battery pack obtained in real time; wherein, the median terminal voltage curve is obtained by sorting the terminal voltages of each battery cell at any moment within the charging voltage curve segments; A distance determination module, configured to determine the Hausdorff distance between the charging voltage curve segments of each battery cell and the median terminal voltage curve; A short-circuit evaluation module, which is configured to determine that an early internal short circuit has occurred in the battery cell corresponding to the Hausdorff distance if it is determined that the Hausdorff distance is greater than a preset distance threshold.

8. An electronic device, characterized in that, The electronic device includes a memory and a processor. A computer program is stored in the memory. When the computer program is executed by the processor, the processor is caused to execute the steps of the battery pack short-circuit evaluation method according to any one of claims 1-6.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed, the steps of the battery pack short-circuit evaluation method according to any one of claims 1-6 are implemented.

10. A computer program product, characterized in that, The computer program product includes a computer program stored on a non-transitory computer-readable storage medium. The computer program includes program instructions. When the program instructions are executed by a computer, the computer is caused to execute the steps of the battery pack short-circuit evaluation method according to any one of claims 1-6.

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