Abnormal Detection Method, Device and Readable Storage Medium for Lithium Iron Phosphate Battery Pack

Abstract

An embodiment of the present application provides a method, device, and readable storage medium for detecting abnormalities in a lithium iron phosphate battery pack, including: obtaining a first voltage relaxation curve and a second voltage relaxation curve of the battery pack to be detected; obtaining a first inflection point corresponding to the first voltage relaxation curve and a second inflection point corresponding to the second voltage relaxation curve, where the first inflection point is a peak point in the first voltage relaxation curve where the degree of mutation corresponding to the highest voltage value satisfies a first preset condition, and the second inflection point is a time point in the second voltage relaxation curve where the degree of mutation corresponding to the lowest voltage value satisfies a second preset condition; performing self-discharge detection processing on the battery pack according to the first inflection point and the second inflection point to obtain a target detection result, where the target detection result indicates whether there is an abnormality in the self-discharge of the battery pack.

Description

Technical Field

[0001] Embodiments of the present disclosure relate to the field of battery technologies, and more particularly, to a method for detecting anomalies in a lithium iron phosphate battery pack, an electronic device, and a computer-readable storage medium. Background Art

[0002] With the strong demand for renewable energy solutions, lithium-ion batteries have been increasingly widely used. Currently, due to cost and technology limitations, battery manufacturers often cannot achieve complete consistency during the battery production process, and even some batteries may exhibit extreme self-discharge anomalies.

[0003] In practice, multiple battery cells are usually used as battery cores and are combined in series or parallel to form a battery pack. When one or more battery cores in the battery pack exhibit self-discharge anomalies, it will directly cause failures in the physical objects using the battery pack, such as vehicles, ships, etc. Therefore, how to detect self-discharge anomalies in the battery pack in a timely and accurate manner has become an urgent problem to be solved. Summary of the Invention

[0004] An object of the present disclosure is to provide a new technical solution for detecting anomalies in a lithium iron phosphate battery pack, especially self-discharge anomalies in a lithium iron phosphate battery pack.

[0005] According to a first aspect of the present disclosure, an embodiment of a method for detecting anomalies in a lithium iron phosphate battery pack is provided, including:

[0006] Obtain a first voltage relaxation curve and a second voltage relaxation curve of a battery pack to be detected, where the battery pack includes multiple battery cores, and the first voltage relaxation curve and the second voltage relaxation curve are curves that respectively reflect the change of the highest voltage and the lowest voltage among the multiple battery cores with the capacity at the same capacity during the charging process of the battery pack;

[0007] Obtain a first inflection point corresponding to the first voltage relaxation curve and a second inflection point corresponding to the second voltage relaxation curve, where the first inflection point is a peak point where the degree of mutation of the highest voltage value corresponding to the first voltage relaxation curve satisfies a first preset condition, and the second inflection point is a peak point where the degree of mutation of the lowest voltage value corresponding to the second voltage relaxation curve satisfies a second preset condition;

[0008] Based on the first inflection point and the second inflection point, perform self-discharge detection processing on the battery pack to obtain a target detection result, where the target detection result indicates whether there is an anomaly in the self-discharge of the battery pack.

[0009] Optionally, obtaining the first inflection point corresponding to the first voltage relaxation curve and obtaining the second inflection point corresponding to the second voltage relaxation curve includes:

[0010] Performing a difference processing on the highest voltage value and the capacity at each point in the first voltage relaxation curve to obtain a first voltage difference capacity curve;

[0011] Performing a difference processing on the lowest voltage value and the capacity at each point in the second voltage relaxation curve to obtain a second voltage difference capacity curve;

[0012] Obtaining the first inflection point according to the first voltage difference capacity curve and obtaining the second inflection point according to the second voltage difference capacity curve.

[0013] Optionally, the first inflection point is the second peak value point in the first voltage difference capacity curve;

[0014] The second inflection point includes a first sub-inflection point and a second sub-inflection point, where the first sub-inflection point is the first peak value point in the second voltage difference capacity curve, and the second sub-inflection point is the second peak value point in the second voltage difference capacity curve;

[0015] Performing a self-discharge detection process on the battery pack according to the first inflection point and the second inflection point to obtain a target detection result, includes:

[0016] Obtaining the absolute value of the difference between the first capacity at the first inflection point and the second capacity at the first sub-inflection point as a first capacity difference;

[0017] Obtaining the absolute value of the difference between the first capacity and the third capacity at the second sub-inflection point as a second capacity difference;

[0018] Performing a self-discharge detection process on the battery pack according to at least one of the first capacity difference and the second capacity difference to obtain the target detection result.

[0019] Optionally, performing a self-discharge detection process on the battery pack according to at least one of the first capacity difference and the second capacity difference to obtain the target detection result, includes:

[0020] When the first capacity difference is not greater than a first preset threshold, and / or the second capacity difference is not less than a second preset threshold, setting the target detection result as information indicating that the battery pack has abnormal self-discharge.

[0021] Optionally, performing a self-discharge detection process on the battery pack according to the first inflection point and the second inflection point to obtain a target detection result, further includes:

[0022] Obtain the state of charge deviation value corresponding to the battery pack at the first inflection point and / or at the second inflection point, where the state of charge deviation value represents the deviation degree between the actual state of charge and the estimated state of charge of the battery pack at the corresponding inflection point, and the estimated state of charge is the value of the state of charge of the battery estimated at the inflection point;

[0023] When the state of charge deviation value is not less than a preset deviation threshold, set the target detection result to information indicating abnormal self-discharge of the battery pack.

[0024] Optionally, the obtaining the state of charge deviation value of the battery pack at the first inflection point and / or at the second inflection point includes:

[0025] Obtain the voltage-state-of-charge relaxation curve corresponding to the battery pack, where the voltage-state-of-charge relaxation curve is a curve reflecting the corresponding relationship between the state of charge of the battery pack and the open-circuit voltage;

[0026] Perform a difference operation on the voltage-state-of-charge relaxation curve to obtain a voltage-difference state-of-charge curve;

[0027] Obtain the estimated state of charge according to the voltage-difference state-of-charge curve;

[0028] Obtain the actual state of charge according to the capacity corresponding to the battery pack at the first inflection point and / or at the second inflection point and the nominal capacity of the battery pack;

[0029] Obtain the absolute value of the difference between the actual state of charge and the estimated state of charge as the state of charge deviation value.

[0030] Optionally, the obtaining the first voltage relaxation curve and the second voltage relaxation curve of the battery pack to be detected includes:

[0031] Obtain the first AC charging data corresponding to the battery pack, where the first AC charging data includes the current value, the highest voltage value, the lowest voltage value, and the initial state of charge at each moment during the charging process of the battery pack;

[0032] Obtain the first voltage relaxation curve and the second voltage relaxation curve according to the first AC charging data.

[0033] Optionally, the obtaining the first voltage relaxation curve and the second voltage relaxation curve according to the first AC charging data includes:

[0034] Perform data cleaning on the first AC charging data, and sort the first AC charging data after the data cleaning in chronological order to obtain the second AC charging data;

[0035] Calculate the initial capacity of the battery pack at the initial moment according to the nominal capacity of the battery pack and the initial state of charge;

[0036] Obtain the capacity of the battery pack corresponding to each moment according to the current corresponding to each moment in the second AC charging data and the initial capacity;

[0037] Obtain the first voltage relaxation curve and the second voltage relaxation curve according to the initial capacity, the highest voltage value at each moment, the lowest voltage value at each moment, and the capacity at each moment.

[0038] Optionally, the obtaining the first voltage relaxation curve and the second voltage relaxation curve according to the initial capacity, the highest voltage value at each moment, the lowest voltage value at each moment, and the capacity at each moment includes:

[0039] Generate a first initial voltage relaxation curve and a second initial voltage relaxation curve according to the initial capacity, the highest voltage value at each moment, the lowest voltage value at each moment, and the capacity at each moment;

[0040] Perform smoothing filtering on the first initial voltage relaxation curve and the second initial voltage relaxation curve respectively to obtain the first voltage relaxation curve and the second voltage relaxation curve.

[0041] According to a second aspect of the present disclosure, an embodiment of an electronic device is provided, including:

[0042] A memory for storing executable instructions;

[0043] A processor for operating the electronic device to execute the method described in the first aspect of the present disclosure according to the control of the instructions.

[0044] According to a third aspect of the present disclosure, a computer-readable storage medium is further provided, on which a computer program is stored, and the computer program implements the method described in the first aspect of the present disclosure when executed by a processor.

[0045] One beneficial effect of the embodiments of the present disclosure is that for a lithium iron phosphate battery pack to be detected, by obtaining a first voltage relaxation curve and a second voltage relaxation curve that respectively reflect the highest voltage and the lowest voltage among multiple battery cells of the battery pack changing with the capacity at the same capacity during the charging process of the battery pack, according to the first voltage relaxation curve and the second voltage relaxation curve, a first inflection point reflecting a sudden change in the highest voltage during the charging process of the battery pack and a second inflection point reflecting a sudden change in the lowest voltage are obtained. According to the positional difference between the two inflection points, a target detection result indicating whether there is abnormal self-discharge in the battery pack during actual use can be obtained timely and accurately.

[0046] Other features and advantages of the present specification will become clear through the following detailed description of the exemplary embodiments of the present specification with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] The drawings incorporated in the specification and constituting a part of the specification illustrate the embodiments of the present specification and, together with the description thereof, are used to explain the principles of the present specification.

[0048] Figure 1 is a flowchart of a method for detecting abnormalities in a lithium iron phosphate battery pack provided by an embodiment of the present disclosure.

[0049] Figure 2 is a schematic diagram of the first voltage relaxation curve and the second voltage relaxation curve provided by an embodiment of the present disclosure.

[0050] Figure 3 is a schematic diagram of the hardware structure of an electronic device provided by an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0051] Now, various exemplary embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. It should be noted that: unless otherwise specifically stated, the relative arrangements of components and steps, numerical expressions, and numerical values set forth in these embodiments do not limit the scope of the present invention.

[0052] The following description of at least one exemplary embodiment is merely illustrative in nature and in no way serves as a limitation on the present invention or its application or use.

[0053] Technologies, methods, and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and devices should be regarded as part of the specification.

[0054] In all the examples shown and discussed here, any specific value should be construed as merely exemplary and not as a limitation. Therefore, other examples of the exemplary embodiments may have different values.

[0055] It should be noted that similar reference numerals and letters refer to similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0056] <Method Embodiment>

[0057] In the related art, when performing self-discharge anomaly detection on a battery, the general method is to first let the battery to be tested stand for a period of time under set temperature, humidity, and magnetic field to promote the battery's self-discharge. After that, the battery is demagnetized and its internal resistance and open-circuit voltage are measured. Based on this internal resistance and open-circuit voltage, self-discharge anomaly detection is performed on the battery. Additionally, in the related art, there is also a method of performing self-discharge anomaly detection on the battery by measuring the open-circuit voltage after the battery is fully charged under constant voltage and constant current and the open-circuit voltage after high-temperature storage. It can be seen from this that when performing self-discharge anomaly detection on a battery in the existing technology, it is only possible to detect the battery at the production end, that is, before the battery leaves the factory. Moreover, all such methods require the battery to be left standing for a long time and constant voltage and constant current charge and discharge tests to be performed on the battery. Therefore, all such self-discharge anomaly detection methods for batteries have the problem that they cannot timely and accurately detect anomalies in the battery throughout its entire life cycle.

[0058] To solve the above problems, an embodiment of the present disclosure provides a method for detecting anomalies in a lithium iron phosphate battery pack. Please refer to Figure 1 , which is a schematic flowchart of the method for detecting anomalies in a lithium iron phosphate battery pack provided by an embodiment of the present disclosure. This method can be implemented in an electronic device, which can be, for example, a server.

[0059] It should be noted that in the embodiments of the present disclosure, the battery pack to be detected refers to a lithium iron phosphate battery (LFP, Lithium Iron Phosphate Battery), that is, an LFP lithium-ion battery pack. Of course, according to needs, this anomaly detection method can also be applied to the anomaly detection of other battery packs, and no special limitation is made here.

[0060] In specific implementation, the battery pack to be detected can be a battery pack constructed by connecting multiple battery cells in series or in parallel, etc. Taking the battery pack to be detected as an example of being constructed by connecting multiple battery cells in series, for the same type of lithium battery constructed in series, the increment of the state of charge (SOC, State Of Charge) during AC charging, that is, ΔSOC, is the same. On the other hand, for a lithium-ion battery, the true SOC corresponding to this battery cell at the voltage inflection point is the same. Therefore, the order of appearance of the voltage inflection points during the charging process of the battery pack represents the difference in its true SOC, that is, the battery cell with self-discharge anomaly appears at the inflection point last.

[0061] As Figure 1 shown, the method of this embodiment may include the following steps S1100 - S1300, which will be described in detail below.

[0062] Step S1100, obtaining a first voltage relaxation curve and a second voltage relaxation curve of a battery pack to be detected, where the battery pack includes multiple battery cells, and the first voltage relaxation curve and the second voltage relaxation curve are respectively curves reflecting the change of the highest voltage and the lowest voltage among the multiple battery cells with the capacity at the same capacity during the charging process of the battery pack.

[0063] Specifically, in an embodiment of the present disclosure, the first voltage relaxation curve and the second voltage relaxation curve can be obtained by obtaining the same capacity of the multiple battery cells at the same moment during the charging of the battery pack to be detected, such as AC charging, that is, the first voltage relaxation curve and the second voltage relaxation curve corresponding to the highest voltage and the lowest voltage among the multiple battery cells at the same battery capacity. By detecting and extracting the first inflection point and the second inflection point where the voltage value mutation degree in these two curves meets the first and second preset conditions, it is determined whether the battery has abnormal self - discharge according to the difference in the positions of the first inflection point and the second inflection point. Hereinafter, how to obtain the first voltage relaxation curve and the second voltage relaxation curve will be described first.

[0064] In one embodiment, the obtaining of the first voltage relaxation curve and the second voltage relaxation curve of the battery pack to be detected includes: obtaining first AC charging data corresponding to the battery pack, where the first AC charging data includes the current value, the highest voltage value, the lowest voltage value, and the initial state of charge at each moment during the charging process of the battery pack; and obtaining the first voltage relaxation curve and the second voltage relaxation curve according to the first AC charging data.

[0065] In this embodiment, the obtaining of the first voltage relaxation curve and the second voltage relaxation curve according to the first AC charging data includes: performing data cleaning processing on the first AC charging data, and sorting the first AC charging data after the data cleaning processing in chronological order to obtain second AC charging data; calculating the initial capacity of the battery pack at the initial moment according to the nominal capacity and the initial state of charge of the battery pack; obtaining the capacity of the battery pack at each moment according to the current at each moment in the second AC charging data and the initial capacity; and obtaining the first voltage relaxation curve and the second voltage relaxation curve according to the initial capacity, the highest voltage value at each moment, the lowest voltage value at each moment, and the capacity at each moment.

[0066] Specifically, in view of the problems of cumbersome steps, lack of timeliness and accuracy in the existing self-discharge anomaly detection of battery packs. When detecting, it can only be carried out at the production end, that is, the battery pack is placed in a specific environment for a long time before leaving the factory, and then detected based on the test data obtained from the constant voltage and constant current charge and discharge of the battery pack. In the embodiments of the present disclosure, the AC charging data uploaded during the entire life cycle of the battery pack at the production end and the usage end can be obtained based on the cloud platform. Based on this AC charging data, the first voltage relaxation curve and the second voltage relaxation curve can be sorted out.

[0067] In this embodiment, the data cleaning process for the first AC charging data can be the elimination process for the data outliers in the first AC charging data caused by various reasons such as hardware failures, communication failures, and parsing errors.

[0068] In addition, when sorting the first AC charging data after the data cleaning process, specifically, it can be sorted in ascending order according to the data generation time to obtain high-quality second AC charging data that changes with time. Then, based on this second AC charging data, the first voltage relaxation curve and the second voltage relaxation curve can be obtained.

[0069] The calculation of the initial capacity of the battery pack at the initial moment according to the nominal capacity and the initial state of charge of the battery pack can be specifically: multiplying the initial state of charge by the nominal capacity to obtain the initial capacity of the battery pack at the initial moment, that is, at the t0 moment.

[0070] The obtaining of the moment capacity of the battery pack corresponding to each moment according to the moment current corresponding to each moment in the second AC charging data and the initial capacity can be specifically: multiplying the moment current corresponding to the next moment after the initial moment, that is, the t1 moment, by the time interval between t1 and t0 to obtain the capacity increment of the t1 moment relative to the t0 moment, and then adding the initial capacity to this capacity increment to obtain the moment capacity of the battery pack at the t1 moment; then, calculate the capacity increment of the next moment t2 after the t1 moment relative to the t1 moment in turn, and then obtain the moment capacity of the t2 moment; and so on, that is, the moment capacity of the battery pack corresponding to each moment can be obtained.

[0071] After obtaining the initial capacity of the battery pack, the highest voltage value, the lowest voltage value and the capacity at each moment according to the above steps, the first voltage relaxation curve and the second voltage relaxation curve can be sorted out.

[0072] It should be noted that, in specific implementation, in order to improve the accuracy of the processing result, the obtaining of the first voltage relaxation curve and the second voltage relaxation curve according to the initial capacity, the highest voltage value at each moment, the lowest voltage value at each moment, and the capacity at each moment may also be: generating a first initial voltage relaxation curve and a second initial voltage relaxation curve according to the initial capacity, the highest voltage value at each moment, the lowest voltage value at each moment, and the capacity at each moment; and respectively performing smoothing filtering processing on the first initial voltage relaxation curve and the second initial voltage relaxation curve to obtain the first voltage relaxation curve and the second voltage relaxation curve.

[0073] Step S1200, obtaining a first inflection point corresponding to the first voltage relaxation curve, and obtaining a second inflection point corresponding to the second voltage relaxation curve, where the first inflection point is a peak point in the first voltage relaxation curve where the mutation degree corresponding to the highest voltage value satisfies a first preset condition, and the second inflection point is a peak point in the second voltage relaxation curve where the mutation degree corresponding to the lowest voltage value satisfies a second preset condition; and step S1300, performing self-discharge detection processing on the battery pack according to the first inflection point and the second inflection point to obtain a target detection result, where the target detection result indicates whether there is an abnormality in the self-discharge of the battery pack.

[0074] Please refer to Figure 2 , which is a schematic diagram of the first voltage relaxation curve and the second voltage relaxation curve provided by an embodiment of the present disclosure. As Figure 2 shown, generally, in the curves of the highest voltage and the lowest voltage of a battery pack, that is, an LFP lithium-ion battery pack, changing with the capacity, there will be three intervals where the voltage changes relatively slowly, and such intervals can be called voltage platform regions. And there is often a region where the voltage changes relatively fast between two voltage platform regions. The point where the voltage changes fastest, that is, the point with the highest mutation degree, in this region can be called a voltage inflection point. Generally, it is distinguished by the voltage level. The one with a higher voltage can be called a high voltage transition point (HVTP), and the one with a lower voltage can be called a low voltage transition point (LVTP).

[0075] In the embodiments of the present disclosure, unless otherwise specified, the first inflection point may be the high voltage inflection point in the first voltage relaxation curve, that is, the HVTP corresponding to the first voltage relaxation curve. The second inflection point includes a first sub-inflection point and a second sub-inflection point, and these two sub-inflection points may be the low voltage inflection point and the high voltage inflection point corresponding to the second voltage relaxation curve respectively, that is, the LVTP and HVTP corresponding to the second voltage relaxation curve.

[0076] The following describes how to obtain the first inflection point and the second inflection point.

[0077] In one embodiment, obtaining the first inflection point corresponding to the first voltage relaxation curve and obtaining the second inflection point corresponding to the second voltage relaxation curve includes: performing a difference processing on the highest voltage value and the capacity at each point of the first voltage relaxation curve to obtain a first voltage difference capacity curve; performing a difference processing on the lowest voltage value and the capacity at each point of the second voltage relaxation curve to obtain a second voltage difference capacity curve; obtaining the first inflection point according to the first voltage difference capacity curve, and obtaining the second inflection point according to the second voltage difference capacity curve.

[0078] Specifically, first, through the formula d V / d Q perform a difference processing on the voltage and the capacity at each point of the first voltage relaxation curve and the second voltage relaxation curve to obtain a first voltage difference capacity curve and a second voltage difference capacity curve, where d V represents the voltage difference at each point of the corresponding curve, and d Q represents the capacity difference at each point of the corresponding curve.

[0079] After obtaining the first voltage difference capacity curve and the second voltage difference capacity curve, the second peak value point in the first voltage difference capacity curve can be used as the first inflection point, that is, the peak value point corresponding to the HVTP of the highest voltage V max of the battery pack; the first peak value point in the second voltage difference capacity curve can be used as the first sub-inflection point in the second inflection point, that is, the peak value point corresponding to the LVTP of the lowest voltage V min of the battery pack; and the second peak value point in the second voltage difference capacity curve can be used as the second sub-inflection point in the second inflection point, that is, the peak value point corresponding to the HVTP of the lowest voltage V min of the battery.

[0080] After obtaining the above first inflection point and second inflection point, in the embodiments of the present disclosure, performing a self-discharge detection process on the battery pack according to the first inflection point and the second inflection point to obtain a target detection result includes: obtaining the absolute value of the difference between the first capacity at the first inflection point and the second capacity at the first sub-inflection point as a first capacity difference; obtaining the absolute value of the difference between the first capacity and the third capacity at the second sub-inflection point as a second capacity difference; performing a self-discharge detection process on the battery pack according to at least one of the first capacity difference and the second capacity difference to obtain the target detection result.

[0081] Let Q1 represent the first capacity, Q2 represent the second capacity, Q3 represent the third capacity, ΔQ1 represent the first capacity difference, and ΔQ2 represent the second capacity difference. Then, the above-mentioned first capacity difference and second capacity difference can be calculated respectively through the formulas ΔQ1 = |Q2 - Q1| and ΔQ2 = |Q3 - Q1|.

[0082] After obtaining the first capacity difference and the second capacity difference through the above steps, according to at least one of the first capacity difference and the second capacity difference, perform a self-discharge detection process on the battery pack to obtain a target detection result, which can be: when the first capacity difference is not greater than the first preset threshold, and / or, when the second capacity difference is not less than the second preset threshold, set the target detection result as information indicating that the self-discharge of the battery pack is abnormal; and, it can also be when the first capacity difference is greater than the first preset threshold and the second capacity difference is less than the second preset threshold, set the target detection result as information indicating that the self-discharge of the battery pack is normal.

[0083] Specifically, let ΔQ1 represent the first capacity difference, ΔQ2 represent the second capacity difference, th1 represent the first preset threshold corresponding to the first capacity difference, and th2 represent the second preset threshold corresponding to the second capacity difference. Then, when ΔQ1 ≤ th1 or ΔQ2 ≥ th2, it can be determined that the self-discharge of the battery is abnormal; and when ΔQ1 > th1 or ΔQ2 < th2, it can be determined that the self-discharge of the battery is normal.

[0084] It should be noted that in the above description, the first inflection point is taken as the high-voltage inflection point in the first voltage relaxation curve, that is, the second high-peak value point HVTP corresponding to the first voltage relaxation curve is taken as an example for illustration. In one embodiment, to improve the accuracy of the judgment result, the first inflection point may also include a third sub-inflection point and a fourth sub-inflection point. Among them, the third sub-inflection point may be the low-voltage inflection point in the first voltage relaxation curve, that is, the first high-peak value point LVTP corresponding to the first voltage relaxation curve, and the fourth sub-inflection point may still be the high-voltage inflection point in the first voltage relaxation curve, that is, the second high-peak value point HVTP corresponding to the first voltage relaxation curve. When performing self-discharge abnormality detection processing on the battery pack according to the first inflection point and the second inflection point, in addition to obtaining the above first capacity difference and second capacity difference by calculating the absolute value of the difference between the first capacity at the fourth sub-inflection point and the above second capacity and the above third capacity, the absolute value of the difference between the fourth capacity at the third sub-inflection point and the above second capacity and the above third capacity can also be obtained to obtain the third capacity difference and the fourth capacity difference, and the battery pack is subjected to self-discharge abnormality detection processing according to at least one of the first capacity difference, the second capacity difference, the third capacity difference, and the fourth capacity difference. In addition, in another embodiment of the present application, after obtaining the absolute value of the difference between the fourth capacity at the third sub-inflection point and the above second capacity and the above third capacity to obtain the third capacity difference and the fourth capacity difference, the battery pack is subjected to self-discharge detection processing according to at least one of the third capacity difference and the fourth capacity difference to obtain a target detection result, which may be: when the third capacity difference is not less than a third preset threshold, and / or, the fourth capacity difference is not greater than a fourth preset threshold, setting the target detection result as information indicating that the battery pack has abnormal self-discharge; and, when the third capacity difference is less than the third preset threshold and the fourth capacity difference is greater than the fourth preset threshold, setting the target detection result as information indicating that the battery pack has normal self-discharge.

[0085] The above has described in detail how to perform self-discharge abnormality detection processing on the battery pack according to the first inflection point and the second inflection point. In one embodiment of the present disclosure, the battery pack can also be subjected to self-discharge detection processing according to the following steps based on the first inflection point and the second inflection point to obtain a target detection result: obtaining the state-of-charge deviation value corresponding to the battery pack at the first inflection point and / or at the second inflection point, where the state-of-charge deviation value represents the deviation degree between the actual state of charge and the estimated state of charge of the battery pack at the corresponding inflection point, and the estimated state of charge is the value of the estimated state of charge of the battery at the inflection point; when the state-of-charge deviation value is not less than a preset deviation threshold, setting the target detection result as information indicating that the battery pack has abnormal self-discharge.

[0086] It should be noted that the state of charge deviation value can directly be the SOC value of the battery pack. In this case, the preset deviation threshold can correspond to the state of charge deviation threshold. Of course, when specifically implementing this embodiment, it can also be that after obtaining the state of charge deviation value, by multiplying the state of charge deviation value by the initial capacity of the battery pack at the initial moment, to obtain the capacity deviation value corresponding to the battery pack at the corresponding inflection point. Then at this time, the preset deviation threshold can correspond to the capacity deviation threshold.

[0087] In this embodiment, the state of charge deviation value of the battery pack at the first inflection point and / or at the second inflection point can be obtained through the following steps: Obtain the voltage state of charge relaxation curve corresponding to the battery pack, where the voltage state of charge relaxation curve is a curve reflecting the corresponding relationship between the state of charge of the battery pack and the open circuit voltage; perform a difference processing on the voltage state of charge relaxation curve to obtain a voltage difference state of charge curve; obtain an estimated state of charge according to the voltage difference state of charge curve; obtain the actual state of charge according to the corresponding capacity of the battery pack at the first inflection point and / or at the second inflection point and the nominal capacity of the battery; obtain the absolute value of the difference between the actual state of charge and the estimated state of charge as the state of charge deviation value.

[0088] Specifically, the first state of charge deviation value, the second state of charge deviation value, and the third state of charge deviation value corresponding to the battery pack at the first inflection point, at the first sub - inflection point of the second inflection point, and at the second sub - inflection point of the second inflection point can be represented by ΔSOC1, ΔSOC2, and ΔSOC3 respectively; then the actual state of charge of the battery pack at the first inflection point can be obtained through the following formula: The first actual state of charge = the first capacity / the battery nominal capacity, the second actual state of charge = the second capacity / the battery nominal capacity, the third actual state of charge = the third capacity / the battery nominal capacity.

[0089] The first estimated state of charge, the second estimated state of charge, and the third estimated state of charge corresponding to the estimated inflection points, or which can also be called the theoretical inflection points, at the first inflection point, the first sub - inflection point of the second inflection point, and the second sub - inflection point of the second inflection point of the battery pack can be obtained through their respectively corresponding voltage state of charge relaxation curves.

[0090] Specifically, in this embodiment, the voltage state of charge relaxation curve may respectively include a first voltage state of charge sub-relaxation curve and a second voltage state of charge sub-relaxation curve, wherein the first voltage state of charge sub-relaxation curve may be a curve reflecting the corresponding relationship between the state of charge of the battery pack and the highest open-circuit voltage, and the second voltage state of charge sub-relaxation curve may be a curve reflecting the corresponding relationship between the state of charge of the battery pack and the lowest open-circuit voltage; then, by respectively performing differential processing on the first and second voltage state of charge sub-relaxation curves, and based on the inflection point data in the corresponding first voltage differential state of charge sub-relaxation curve and second voltage differential state of charge sub-relaxation curve, the above-mentioned first estimated state of charge, second estimated state of charge, and third estimated state of charge can be obtained. For example, the first estimated state of charge may be the state of charge corresponding to the high-voltage inflection point, i.e., HVTP, in the first voltage differential state of charge sub-relaxation curve, the second estimated state of charge may be the state of charge corresponding to the low-voltage inflection point, i.e., LVTP, in the second voltage differential state of charge sub-relaxation curve, and the third estimated state of charge may be the state of charge corresponding to the high-voltage inflection point, i.e., HVTP, in the second voltage differential state of charge sub-relaxation curve.

[0091] After obtaining the above-mentioned first state of charge deviation value, second state of charge deviation value, third state of charge deviation value, first estimated state of charge, second estimated state of charge, and third estimated state of charge, by respectively calculating the absolute value of the difference between each actual state of charge and the corresponding estimated state of charge, ΔSOC1, ΔSOC2, and ΔSOC3 can be obtained.

[0092] After obtaining ΔSOC1, ΔSOC2, and ΔSOC3 through the above processing, by comparing their magnitude relationships with the corresponding preset deviation thresholds, it is possible to determine whether there is an abnormal self-discharge in the battery pack. Specifically, the preset deviation thresholds may respectively include a third preset threshold th3, a fourth preset threshold th4, and a fifth preset threshold th5 corresponding to the above three state-of-charge deviation thresholds. Then, by comparing the magnitude relationships between ΔSOC1 and th3, ΔSOC2 and th4, and ΔSOC3 and th5, it is possible to determine whether there is an abnormal self-discharge in the battery pack. Of course, in specific implementation, it is also possible to determine whether there is an abnormal self-discharge in the battery pack according to the magnitude relationship between at least one of ΔSOC1, ΔSOC2, and ΔSOC3 and the corresponding preset deviation threshold; or, the first inflection point may also include a third sub-inflection point and a fourth sub-inflection point. Among them, the third sub-inflection point may be the low-voltage inflection point in the first voltage relaxation curve, that is, the LVTP corresponding to the first voltage relaxation curve, and the fourth sub-inflection point may still be the high-voltage inflection point in the first voltage relaxation curve. Then, the battery pack can be subjected to self-discharge abnormal detection processing according to at least one of the state-of-charge deviation values corresponding to the first sub-inflection point, the second sub-inflection point, the third sub-inflection point, and the fourth sub-inflection point. The detailed processing process will not be elaborated here.

[0093] It should be noted that in specific implementation, the battery pack can be subjected to self-discharge abnormal detection processing according to at least one of the above one or more embodiments for self-discharge detection of the battery pack, and no special limitation is made here.

[0094] In summary, the abnormal detection method for the lithium iron phosphate battery pack provided by the embodiments of the present disclosure is directed to the lithium iron phosphate battery pack to be detected. By obtaining the first voltage relaxation curve and the second voltage relaxation curve that respectively reflect the highest voltage and the lowest voltage of multiple battery cells in the battery pack changing with the capacity at the same capacity at the same moment during the charging process of the battery pack, according to the first voltage relaxation curve and the second voltage relaxation curve, a first inflection point reflecting the sudden change of the highest voltage during the charging process of the battery pack and a second inflection point where the lowest voltage suddenly changes are obtained. According to the position difference between the two inflection points, a target detection result indicating whether there is an abnormal self-discharge in the battery pack during actual use can be obtained in a timely and accurate manner.

[0095] <Device Embodiment>

[0096] Corresponding to the above method embodiment, in this embodiment, an electronic device is further provided. Please refer to Figure 3 which is a schematic structural diagram of an electronic device provided by the embodiments of the present disclosure.

[0097] As Figure 3As shown, the electronic device 3000 may include a processor 3200 and a memory 3100. The memory 3100 is used to store executable instructions. The processor 3200 is used to operate the electronic device according to the control of the instructions to execute the method according to any embodiment of the present disclosure.

[0098] <Medium Embodiment>

[0099] Corresponding to the above method embodiment, this embodiment also provides a computer-readable storage medium. A computer program is stored on the computer-readable storage medium, and when the computer program is executed by a processor, the method described in any method embodiment of the present disclosure is implemented.

[0100] One embodiment or multiple embodiments of this specification may be a system, a method, and / or a computer program product. The computer program product may include a computer-readable storage medium having computer-readable program instructions thereon for causing a processor to implement various aspects of this specification.

[0101] The computer-readable storage medium may be a tangible device that can hold and store instructions used by an instruction execution device. The computer-readable storage medium may be, for example, but not limited to, an electrical storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination of the above. More specific examples (a non-exhaustive list) of the computer-readable storage medium include: a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), a static random access memory (SRAM), a portable compact disc read-only memory (CD-ROM), a digital versatile disc (DVD), a memory stick, a floppy disk, a mechanically encoded device, such as a punched card or raised structures in grooves storing instructions thereon, and any suitable combination of the above. The computer-readable storage medium used herein is not construed as an instantaneous signal itself, such as a radio wave or other freely propagating electromagnetic wave, an electromagnetic wave propagated through a waveguide or other transmission medium (e.g., an optical pulse through an optical fiber cable), or an electrical signal transmitted through a wire.

[0102] The computer-readable program instructions described herein may be downloaded from a computer-readable storage medium to various computing / processing devices, or downloaded to an external computer or external storage device through a network, such as the Internet, a local area network, a wide area network, and / or a wireless network. The network may include copper transmission cables, optical fiber transmission, wireless transmission, routers, firewalls, switches, gateway computers, and / or edge servers. A network adapter or network interface in each computing / processing device receives the computer-readable program instructions from the network and forwards the computer-readable program instructions for storage in the computer-readable storage medium in each computing / processing device.

[0103] The computer program instructions for performing the operations of the embodiments of this specification may be assembly instructions, instruction set architecture (ISA) instructions, machine instructions, machine-related instructions, microcode, firmware instructions, state setting data, or source code or object code written in any combination of one or more programming languages, including object-oriented programming languages such as Smalltalk, C++, etc., and conventional procedural programming languages such as the "C" language or similar programming languages. The computer-readable program instructions may be executed entirely on the user's computer, partially on the user's computer, executed as a stand-alone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In the case of a remote computer, the remote computer may be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or may be connected to an external computer (e.g., through the Internet using an Internet service provider). In some embodiments, by using the state information of the computer-readable program instructions to customize an electronic circuit, such as a programmable logic circuit, a field-programmable gate array (FPGA), or a programmable logic array (PLA), the electronic circuit can execute the computer-readable program instructions to implement various aspects of this specification.

[0104] Aspects of this specification are described herein with reference to the flowcharts and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this specification. It should be understood that each block of the flowcharts and / or block diagrams, and combinations of blocks in the flowcharts and / or block diagrams, can be implemented by computer-readable program instructions.

[0105] These computer-readable program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing apparatus, thereby producing a machine such that when these instructions are executed by the processor of the computer or other programmable data processing apparatus, a device is produced that implements the functions / acts specified in one or more blocks of the flowchart and / or block diagram. These computer-readable program instructions can also be stored in a computer-readable storage medium, and these instructions cause a computer, a programmable data processing apparatus, and / or other devices to work in a specific manner, so that the computer-readable medium storing the instructions includes a manufactured article that includes instructions for implementing various aspects of the functions / acts specified in one or more blocks of the flowchart and / or block diagram.

[0106] Computer-readable program instructions may also be loaded onto a computer, other programmable data processing apparatus, or other device, causing a series of operational steps to be performed on the computer, other programmable data processing apparatus, or other device to produce a computer-implemented process such that the instructions executed on the computer, other programmable data processing apparatus, or other device implement the functions / acts specified in one or more boxes of the flowchart and / or block diagram.

[0107] The flowcharts and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of the present specification. In this regard, each box in the flowchart or block diagram may represent a module, a segment of a program, or a portion of an instruction, which contains one or more executable instructions for implementing the specified logical function. In some alternative implementations, the functions noted in the boxes may occur in a different order than noted in the figures. For example, two consecutive boxes may actually be executed substantially in parallel, or they may sometimes be executed in the reverse order, depending on the functions involved. It should also be noted that each box in the block diagrams and / or flowcharts, and combinations of boxes in the block diagrams and / or flowcharts, can be implemented by a dedicated hardware-based system that performs the specified functions or acts, or by a combination of dedicated hardware and computer instructions. As is well known to those of ordinary skill in the art, implementation by hardware, implementation by software, and implementation by a combination of software and hardware are equivalent.

[0108] The embodiments of the present specification have been described above. The above description is exemplary and not exhaustive, and is not limited to the disclosed embodiments. Many modifications and variations will be apparent to those of ordinary skill in the art in the technical field without departing from the scope and spirit of the described embodiments. The choice of terms used herein is intended to best explain the principles of the embodiments, the practical application, or improvements to the technology in the market, or to enable other ordinary skill in the art in the technical field to understand the embodiments disclosed herein. The scope of the present application is defined by the appended claims.

Claims

1. An abnormal detection method for a lithium iron phosphate battery pack, characterized in that, Including: Obtaining a first voltage relaxation curve and a second voltage relaxation curve of a battery pack to be detected, where the battery pack includes multiple battery cells, and the first voltage relaxation curve and the second voltage relaxation curve are respectively curves reflecting the change of the highest voltage and the lowest voltage among the multiple battery cells with the capacity at the same capacity during the charging process of the battery pack; Obtaining a first inflection point corresponding to the first voltage relaxation curve and a second inflection point corresponding to the second voltage relaxation curve, where the first inflection point is a peak point where the mutation degree corresponding to the highest voltage value in the first voltage relaxation curve meets a first preset condition, and the second inflection point is a peak point where the mutation degree corresponding to the lowest voltage value in the second voltage relaxation curve meets a second preset condition; Performing self-discharge detection processing on the battery pack according to the first inflection point and the second inflection point to obtain a target detection result, where the target detection result indicates whether there is an abnormality in the self-discharge of the battery pack.

2. The method according to claim 1, wherein The obtaining the first inflection point corresponding to the first voltage relaxation curve and the second inflection point corresponding to the second voltage relaxation curve includes: Obtaining a first voltage difference capacity curve by performing difference processing on the highest voltage value and the capacity at each point in the first voltage relaxation curve; Obtaining a second voltage difference capacity curve by performing difference processing on the lowest voltage value and the capacity at each point in the second voltage relaxation curve; Obtaining the first inflection point according to the first voltage difference capacity curve and obtaining the second inflection point according to the second voltage difference capacity curve.

3. The method according to claim 2, wherein The first inflection point includes a second peak value point in the first voltage difference capacity curve; The second inflection point includes a first sub-inflection point and a second sub-inflection point, where the first sub-inflection point is the first peak value point in the second voltage difference capacity curve, and the second sub-inflection point is the second peak value point in the second voltage difference capacity curve; The performing self-discharge detection processing on the battery pack according to the first inflection point and the second inflection point to obtain a target detection result includes: Obtaining the absolute value of the difference between the first capacity at the first inflection point and the second capacity at the first sub-inflection point as a first capacity difference; obtaining the absolute value of the difference between the first capacity and the third capacity at the second sub-inflection point as a second capacity difference; Performing self-discharge detection processing on the battery pack according to at least one of the first capacity difference and the second capacity difference to obtain the target detection result.

4. The method according to claim 3, wherein The performing self-discharge detection processing on the battery pack according to at least one of the first capacity difference and the second capacity difference to obtain the target detection result includes: When the first capacity difference is not greater than a first preset threshold and / or the second capacity difference is not less than a second preset threshold, setting the target detection result as information indicating that the self-discharge of the battery pack is abnormal.

5. The method according to claim 2, characterized in that The performing self-discharge detection processing on the battery pack according to the first inflection point and the second inflection point to obtain a target detection result further includes: Obtain the state of charge deviation value of the battery pack at the first inflection point and / or at the second inflection point, where the state of charge deviation value represents the degree of deviation between the actual state of charge and the estimated state of charge of the battery pack at the corresponding inflection point, and the estimated state of charge is the value of the state of charge of the battery obtained by estimation at the inflection point; When the state of charge deviation value is not less than the preset deviation threshold, set the target detection result to information indicating abnormal self-discharge of the battery pack.

6. The method according to claim 5, characterized in that The obtaining the state of charge deviation value of the battery pack at the first inflection point and / or at the second inflection point includes: Obtain the voltage-state-of-charge relaxation curve corresponding to the battery pack, where the voltage-state-of-charge relaxation curve is a curve reflecting the corresponding relationship between the state of charge of the battery pack and the open-circuit voltage; Perform a difference processing on the voltage-state-of-charge relaxation curve to obtain a voltage difference-state-of-charge curve; Obtain the estimated state of charge according to the voltage difference-state-of-charge curve; Obtain the actual state of charge according to the capacity corresponding to the battery pack at the first inflection point and / or at the second inflection point and the nominal capacity of the battery pack; Obtain the absolute value of the difference between the actual state of charge and the estimated state of charge as the state of charge deviation value.

7. The method according to claim 1, wherein The obtaining the first voltage relaxation curve and the second voltage relaxation curve of the battery pack to be detected includes: Obtain the first AC charging data corresponding to the battery pack, where the first AC charging data includes the current value, the highest voltage value, the lowest voltage value, and the initial state of charge of the battery pack at each moment during the charging process; Obtain the first voltage relaxation curve and the second voltage relaxation curve according to the first AC charging data.

8. The method according to claim 7, wherein The obtaining the first voltage relaxation curve and the second voltage relaxation curve according to the first AC charging data includes: Perform data cleaning processing on the first AC charging data, and sort the first AC charging data after the data cleaning processing in chronological order to obtain second AC charging data; Calculate the initial capacity of the battery pack at the initial moment according to the nominal capacity of the battery pack and the initial state of charge; Obtain the capacity of the battery pack at each moment according to the current at each moment in the second AC charging data and the initial capacity; Obtain the first voltage relaxation curve and the second voltage relaxation curve according to the initial capacity, the highest voltage value at each moment, the lowest voltage value at each moment, and the capacity at each moment.

9. The method according to claim 8, wherein The obtaining the first voltage relaxation curve and the second voltage relaxation curve according to the initial capacity, the highest voltage value at each moment, the lowest voltage value at each moment, and the capacity at each moment includes: Generate a first initial voltage relaxation curve and a second initial voltage relaxation curve according to the initial capacity, the highest voltage value at each moment, the lowest voltage value at each moment, and the capacity at each moment; Perform smoothing filtering on the first initial voltage relaxation curve and the second initial voltage relaxation curve respectively to obtain the first voltage relaxation curve and the second voltage relaxation curve.

10. An electronic device, characterized in that, Comprising: A memory for storing executable instructions; A processor for operating the electronic device to execute the method according to any one of claims 1-9 under the control of the instructions.

11. A computer-readable storage medium, characterized in that, A computer program is stored on the computer-readable storage medium, and the computer program realizes the method according to any one of claims 1-9 when executed by a processor.

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