Method of monitoring battery block of battery

Abstract

The invention relates to a method of monitoring a battery block of a battery. A system and method for monitoring the behavior of battery blocks (b1,..., bn) connected in series. For each of a plurality of points in time (t0, t-1, t-2) and for each battery block, a deviation value ([delta] Ub1,..., [delta] Ubn), which is a voltage deviation of the voltage measurement with respect to an average (M) of the voltage measurements (Ub1,..., Ubn) of the battery block, or a corresponding charge deviation, is calculated. A mapping (10) of the voltage values (U1,..., Uz) or the current values to the deviation values ([delta] U1,..., [delta] Uz) is determined. Each voltage value or current value is assigned an extreme value of those deviation values of the battery block that have been calculated for a point in time at which a voltage measurement or current measurement corresponding to the voltage value or current value is measured. The map (10) is evaluated to detect a potential abnormal state of the battery block.

Description

[0001] The present invention relates to monitoring the behavior of a plurality of battery blocks connected in series in a battery for detecting an abnormal state of one of the plurality of battery blocks. SUMMARY

[0002] Batteries, in particular electrochemical batteries such as lithium-ion batteries, are increasingly used for battery storage. It is desirable to provide an economic, safe and sustainable operation of a battery storage device.

[0003] It is an object of the present invention to provide a novel method of monitoring the behavior of a plurality of battery blocks connected in series in a battery.

[0004] It is desirable that the method allows monitoring the behavior of the battery blocks based on electrical parameters only readily available in a battery management system of a battery storage device.

[0005] It is desirable that the method allows establishing the monitoring of the behavior of the battery blocks in a non-intrusive manner.

[0006] In particular, it is desirable that the method allows monitoring the behavior of the battery blocks based on voltage measurements only at respective points in time or voltage measurements at respective points in time and current measurements.

[0007] Further, it is desirable to be able to automatically detect an abnormal state of one of the plurality of battery blocks, in particular a potentially safety-relevant state and / or a state reflecting a manufacturing defect.

[0008] It is further desirable that the method can detect an abnormal state of the battery blocks without having to rely on an ideal or completely normal battery as a reference.

[0009] The invention is specified in independent claims. Further embodiments are specified in dependent claims.

[0010] According to an aspect of the application, there is provided a method of monitoring the behavior of a plurality of battery blocks connected in series in a battery for detecting a potential abnormal state of one of the plurality of battery blocks. The method comprises, for each of a plurality of time points, providing a voltage measurement of each of the plurality of battery blocks measured at the time point. The method further comprises, for each of the plurality of time points, and for each of the plurality of battery blocks, calculating a deviation value of the battery block. The deviation value is a voltage deviation of the voltage measurement of the battery block with respect to an average of the voltage measurements of the plurality of battery blocks at the time point, or is a charge deviation of the battery block corresponding to the voltage deviation. The method further comprises, for each of the plurality of battery blocks and for a first time frame, determining a mapping of voltage values or current values to deviation values, wherein to each of the voltage values or to each of the current values is assigned an extreme value of those deviation values of the battery block that have been calculated for the respective time points at which the voltage measurement or the current measurement of the battery block corresponding to the voltage value or the current value, respectively, was measured. The respective time points belong to the first time frame. That is, determining the mapping comprises assigning the respective extreme value to the respective voltage value or current value. The mapping of voltage values or current values to deviation values is a mapping of voltage values or current values to deviation values in the form of the extreme values. The method further comprises, for each of the plurality of battery blocks, evaluating the determined mapping for detecting a potential abnormal state of the battery block.

[0011] The battery can also be referred to as "the monitored battery". During use of the battery, the battery blocks connected in series typically undergo the same succession of charging, energy storage, discharging, etc. Furthermore, the battery blocks typically have a similar structure and a similar age, with similar electrical parameters such as capacity. When calculating the deviation values of the battery blocks, the average of the voltage measurements of the battery blocks is used as a "self-generated" reference on a local basis. The voltage measurements stem from the battery blocks being subjected to the same current at a certain time point, as the battery blocks are connected in series. When taken individually, the difference between the voltage measurement of a single battery block and the average of the voltage measurements of the battery blocks can not reveal any significant characteristics. However, by determining the mapping, the deviation values are distinguished according to the voltage measurement (or current measurement) at which the deviation value occurs. This is advantageous, as the deviation of the behavior of a particular battery block with respect to the average of the battery blocks can depend on the voltage. Furthermore, for the voltage values, only the extreme values of the individual deviation values are selected for the mapping. Thus, the evaluation is based on a highly selective mapping, which further emphasizes the extreme values. Thus, based on the voltage measurements, and using the average of the voltage measurements of the battery blocks as a "self-generated" reference, a potential abnormal state of one of the battery blocks connected in series can be detected.

[0012] Because the deviation value calculated by mapping / assignment is chosen as the extreme value, the relevant abnormal deviation value is highlighted relative to the "normal" deviation value that may also occur. This improves the assessment to detect potential abnormal states. Furthermore, since multiple deviation values ​​allow for differentiation of the voltage (or current) at which deviation values ​​(e.g., voltage difference) occur, the behavior of the battery pack can be specifically assessed within one or more specific voltage (or current) ranges. Therefore, even if the behavior appears "normal" in other voltage or current ranges, abnormal behavior of the battery pack within one or more specific voltage (or current) ranges can be detected. For example, deviations specific to predetermined higher / lower voltage sub-ranges of a voltage range that includes multiple voltage measurements can be assessed. Therefore, even if the behavior appears "normal" in an intermediate charging state, abnormal behavior of the battery pack in relatively high / low charging states can be detected. In the following, whenever the assessment / detection of deviations within a sub-range is described, this can include the assessment / detection of deviations specific to that sub-range.

[0013] For example, the extreme values ​​of these deviations could be the calculated deviations with the largest absolute values. Alternatively, the extreme values ​​could include the minimum and maximum values ​​of those deviations.

[0014] The term "battery block" is understood to refer to a unit within a battery or battery storage device, where unit voltage measurements are available. A battery block may include one or more battery units. In particular, a battery block may include multiple battery units connected in parallel. The term "battery block" may also include a single battery unit.

[0015] The battery may include battery modules or battery strings, wherein the plurality of battery modules are connected in series. The battery may be part of a battery storage device. The battery storage device may include a battery management system.

[0016] The term "voltage measurement result" is understood to mean a value obtained by measuring voltage. Providing a voltage measurement result can include measuring voltage to obtain the voltage measurement result. For example, a voltage measurement result can be provided by a battery management system. The voltage measurement result is measured at a corresponding point in time. For example, the voltage measurement may be performed at a specific point in time or may have already occurred at that point in time.

[0017] The calculated deviation value is correlated with the corresponding voltage measurement time point. In other words, the deviation value "appears" at that time point, "appears" at the voltage measurement result, and / or "appears" at the corresponding current measurement result taken at the same time point.

[0018] The calculated deviation value is a signed deviation value; that is, the sign of the voltage deviation relative to the average value of the voltage measurements is retained. Where applicable, the sign of the charge deviation corresponds to the sign of the voltage deviation.

[0019] Charge deviation can be an estimated charge deviation. It can be estimated based on voltage deviation. Charge deviation can be calculated based on the voltage-charge characteristics of a battery cell or multiple battery cells and on voltage measurements of the battery cells. Voltage-charge characteristics can define the relationship between voltage and charge at different voltages. The voltage-charge characteristics of a battery cell can be ideal or estimated. The voltage-charge characteristics of a battery cell can be voltage-charge curves, particularly voltage-SoC curves that describe the relationship between voltage and state of charge (SoC). For example, at a specific voltage (voltage measurement result), the slope or local behavior of the voltage-charge curve describes the relationship between voltage deviation and corresponding charge deviation at that specific voltage.

[0020] The method may include providing current measurement results for multiple battery cells for each of the plurality of time points.

[0021] The first time frame can have a predetermined length or duration. The length of the first time frame can be at least 14 days, preferably at least 20 days, and more preferably at least 28 days. Therefore, voltage measurements at many different charge states of the battery can typically be included in the voltage measurement results. The length of the first time frame can be less than 2 months, preferably less than 1 month. This allows for the detection of the development of abnormal states in the battery pack on a suitable timescale.

[0022] The number of time points belonging to the first time frame can be at least 100,000, preferably at least 400,000.

[0023] Multiple time points can be sequentially spaced, for example, at intervals of one second or longer. The time interval can be at least one second or at least five seconds. The time interval can be one hour or less, 10 minutes or less, 5 minutes or less, or preferably 60 seconds or less.

[0024] The mapped voltage or current values ​​may include at least 20 different values, preferably at least 50 different values. Voltage measurements and / or voltage values ​​may extend over a voltage range of at least 0.5V. Current measurements and / or current values ​​may extend over a current range of at least 0.2C, preferably at least 1C. Herein, 0.2C or 1C represents the charge-discharge rate (C-rate).

[0025] In this embodiment, the average value of the voltage measurements of the multiple battery cells is the median value of the voltage measurements of the multiple battery cells.

[0026] However, the average value can also be the arithmetic mean or other central tendency of the voltage measurements of the battery cells at the corresponding time points.

[0027] In an embodiment, the evaluation includes evaluating a determined mapping relative to at least one reference deviation value, wherein the at least one reference deviation value is at least one predetermined reference deviation value, or wherein the at least one reference deviation value is obtained based on the mapping of other blocks among a plurality of battery blocks, or wherein the at least one reference deviation value is obtained based on the corresponding mapping of the corresponding battery block of the corresponding battery.

[0028] In an embodiment, the evaluation includes evaluating a determined mapping relative to at least one reference mapping, wherein the at least one reference mapping is a predetermined reference mapping, or wherein the at least one reference mapping includes mappings for other blocks among a plurality of battery blocks, or wherein the at least one reference mapping is obtained based on a corresponding mapping of a corresponding battery block for a corresponding battery.

[0029] The corresponding battery can be a battery that is structurally identical to the battery being monitored, or a battery of a similar type to the battery being monitored. The corresponding battery includes all batteries except the one used to provide voltage measurement (the battery being monitored).

[0030] The corresponding mapping of the corresponding battery block for the corresponding battery is obtained in the same manner as the mapping determined for the corresponding block among multiple battery blocks of the monitored battery. That is, the corresponding mapping can be determined in the same manner as the steps of calculating the deviation value and determining the mapping of the corresponding battery block for the monitored battery. Similarly, the deviation value of the corresponding battery block is obtained in the same manner as the deviation value of the corresponding block among multiple battery blocks of the monitored battery. The deviation value of the corresponding battery block can also be referred to as the corresponding deviation value.

[0031] Therefore, the reference deviation value or reference mapping can be obtained based on corresponding measurements of multiple batteries of similar kind (“corresponding batteries”), particularly batteries that are structurally identical to the battery being monitored. This is particularly advantageous because, for example, the behavior of a particular battery block (e.g., battery block #n in a series-connected battery block) can be evaluated relative to the behavior of battery block #n of multiple structurally identical batteries in the field. Although battery block #n may have a specific behavior, this specific behavior may be due to structural differences between series-connected battery blocks and may appear in multiple structurally identical batteries in a similar manner. However, when the behavior of battery block #n differs from the behavior of battery block #n of multiple structurally identical batteries, an anomalous state can be detected. Thus, the detection of potential anomalous states of a single battery block within a battery block is significantly improved. For example, the reference mapping can be the average of reference mappings of multiple corresponding batteries. That is, obtaining the average of the reference mappings is understood to include the average (e.g., an arithmetic mean) of the calculated deviation values ​​for each of the corresponding voltage or current values ​​of the mapping. Obtaining the average of the reference mappings can include interpolating the reference mappings over the voltage or current values.

[0032] Specifically, for example, a potential safety-related state of the battery block can be detected when the deviation of the behavior of a particular battery block relative to the behavior of corresponding battery blocks of multiple corresponding batteries increases over monitoring time. This increase over monitoring time can be determined, for example, by repeating the steps of determining and evaluating the determined mapping for at least one second time frame (e.g., for multiple new second time frames), each second time frame advancing temporally relative to a previous time frame; detecting the deviation for each time frame; and determining the increase in deviation, for example, based on a linear regression of the detected deviation. The increase in deviation can also be determined using other algorithms.

[0033] The second time frame can be an updated time frame. For example, a new second time frame can be processed daily. Each second time frame can overlap with a previous time frame or the first time frame via time overlap. Each first time frame and the second time frame can have the same length or duration.

[0034] In this document, the increase or decrease of monitoring time can include an increase or decrease of time in the direction toward the first time frame (end), specifically, from at least one second time frame toward the first time frame (end). For example, the monitoring time can be extended over a period longer than the length of the corresponding time frame. For example, the steps of determining the mapping and evaluating the determined mapping can be repeated for new / updated time frames, for example, daily or after several days, wherein the number of days is preferably at least 1 and / or preferably less than 8. Each new time frame can overlap with a previous time frame. For example, each new time frame can overlap with a previous time frame by at least one day or the several days.

[0035] Furthermore, embodiments for determining whether the deviation increases with monitoring time are described below. Additionally, embodiments for determining whether the degree of deviation increases with monitoring time are described. This can be determined in a similar manner.

[0036] At least one reference deviation value may be a (statistical) representation of the deviation value of the corresponding battery. Similarly, at least one reference mapping may be a (statistical) representation of the corresponding mapping.

[0037] The method may include: collecting at least one corresponding deviation value for a corresponding battery block specific to the corresponding battery from the corresponding battery. The method may include: determining at least one reference deviation value based on the at least one corresponding deviation value for the corresponding battery block specific to the corresponding battery. The method may include: determining at least one reference mapping based on the at least one corresponding deviation value for the corresponding battery block specific to the corresponding battery.

[0038] In this embodiment, the potential abnormal state of the battery block is a potential safety-related state and / or a state reflecting a manufacturing defect.

[0039] This method may include detecting potential safety-related states and detecting states reflecting manufacturing defects. Specifically, safety-related states can be detected independently of detecting states reflecting manufacturing defects. In particular, a potential safety-related state can be detected when a deviation from expected behavior or from at least one reference mapping is detected to increase over monitoring time.

[0040] In an embodiment, the mapping is a mapping from a voltage value to a deviation value, wherein the steps of determining the mapping and evaluating the determined mapping are repeated for at least one second time frame, wherein the evaluation includes: detecting a negative deviation of the deviation value relative to a first reference deviation value within a predetermined higher voltage sub-range of a voltage range including voltage measurements of the battery cell. The method may include: determining whether the negative deviation increases with (monitoring) time. That is, determining whether the absolute value of the negative deviation increases with monitoring time.

[0041] In particular, negative deviations can be specific to a predetermined higher voltage subrange and / or can be detected only within a predetermined higher voltage subrange.

[0042] This increased negative deviation in the higher voltage range may be caused by charging energy being used for undesirable side reactions, which could lead to unwanted lithium plating in the corresponding battery cell. When lithium dendrites or flat lithium structures accumulate in the battery cell, this can cause internal short circuits, resulting in a strong exothermic reaction. Detecting negative deviation in the higher voltage range allows for timely identification of abnormal conditions, which can help prevent serious damage.

[0043] The method may include: detecting a potential abnormal state of the battery block when it is determined that the negative deviation increases with (monitoring) time, the potential abnormal state being a potential safety-related state.

[0044] The first reference deviation value can be a predetermined first reference deviation value. Alternatively, the first reference deviation value can be a reference deviation value determined based on the mapping of other cells in a plurality of battery cells.

[0045] In an embodiment, the mapping is a mapping from voltage values ​​to deviation values. The evaluation may include: detecting a positive deviation of the deviation value relative to a predetermined second reference deviation value in a predetermined higher voltage subrange of the voltage range including the voltage measurement results of the battery pack, the positive deviation generally increasing with increasing voltage values; and / or detecting a negative deviation of the deviation value relative to a predetermined third reference deviation value in a predetermined lower voltage subrange of the voltage range including the voltage measurement results of the battery pack, the negative deviation generally increasing with decreasing voltage values.

[0046] Specifically, positive deviations can be specific to a predetermined higher voltage subrange and / or can be detected only within the predetermined higher voltage subrange. Similarly, negative deviations can be specific to a predetermined lower voltage subrange and / or can be detected only within the predetermined lower voltage subrange.

[0047] This combination of positive and negative deviations indicates that a particular battery cell appears to have a lower capacity than others. This combination of positive and negative deviations may be due to poor welding quality in the battery cell. Therefore, construction errors (such as poor welding quality) that would otherwise be difficult to detect during battery use can be detected. In particular, detectable deviations may not exist in the intermediate voltage sub-range. Therefore, abnormal states can be detected due to separate evaluations of the higher and lower voltage sub-ranges outside the intermediate voltage sub-range, and due to the selection and allocation of extreme values.

[0048] The method may include detecting potential abnormal states of the battery pack when positive and negative deviations are detected.

[0049] Whether positive deviation generally increases with increasing voltage value, and / or whether negative deviation generally increases with decreasing voltage value, can be determined, for example, by linear regression.

[0050] In one embodiment, the mapping is a mapping from voltage values ​​to deviation values, wherein the method includes: evaluating the determined mapping for each of a plurality of battery blocks to determine whether at least one first mapping and at least one second mapping in the mapping show a corresponding deviation relative to zero deviation, wherein the deviation of at least one first mapping and the deviation of at least one second mapping are generally symmetrical about the sign of the deviation values. The method may include: if this is the case, detecting a potential anomalous state of the corresponding battery block. This can indicate asynchronous behavior of the battery block or battery cell.

[0051] In an embodiment, the mapping is a mapping from voltage values ​​to deviation values, wherein the evaluation includes: detecting a negative deviation of the deviation value relative to a predetermined fourth reference deviation value in a predetermined higher voltage subrange of the voltage range including the voltage measurement results of the battery pack, the negative deviation generally increasing with increasing voltage values; and / or detecting a positive deviation of the deviation value relative to a predetermined fifth reference deviation value in a predetermined lower voltage subrange of the voltage range including the voltage measurement results of the battery pack, the positive deviation generally increasing with decreasing voltage values.

[0052] Specifically, negative deviations can be specific to a predetermined higher voltage subrange and / or can be detected only within the predetermined higher voltage subrange. Similarly, positive deviations can be specific to a predetermined lower voltage subrange and / or can be detected only within the predetermined lower voltage subrange.

[0053] The method may include detecting potential abnormal states of the battery cell when negative and positive deviations are detected.

[0054] In an embodiment, the mapping is a mapping from voltage values ​​to deviation values, wherein the steps of determining the mapping and evaluating the determined mapping are repeated for at least one second time frame. The evaluation may include detecting a negative deviation of the deviation value relative to a seventh reference deviation value within a predetermined lower voltage sub-range of a voltage range including voltage measurements of the battery cell. The method may include determining whether the negative deviation increases over (monitoring) time.

[0055] The method may include: detecting a potential abnormal state of the battery block when it is determined that the negative deviation increases with (monitoring) time, the potential abnormal state being a potential safety-related state.

[0056] The method may further include: determining the rate of increase of the negative deviation. The method may also include: detecting a potential abnormal state of the battery cell when the rate of increase is determined to exceed a reference value; this potential abnormal state is a potential safety-related state.

[0057] This increased negative deviation may be due to lithium plating reactions within the battery cells. Therefore, abnormal states related to lithium plating can be detected even when the battery does not (or infrequently) reach the predetermined higher voltage range during normal battery operation.

[0058] The evaluation may include: evaluating a mapping for a first time frame and a mapping for at least one second time frame using a machine learning algorithm trained to detect potential anomalous states of the battery block as potential safety-related states. The machine learning algorithm may be configured to detect potential anomalous states of the battery block based on a negative deviation increasing over time and / or the rate of increase of the negative deviation. For example, a portion of the corresponding mapping for a predetermined lower voltage subrange of a voltage range may be fed into the machine learning algorithm.

[0059] In one embodiment, the mapping is a mapping from voltage values ​​to deviation values, wherein the method includes: scaling and / or adjusting the determined mapping based on a reference mapping prior to the step of evaluating the mapping, wherein the reference mapping is obtained based on a corresponding mapping of a corresponding battery block for a corresponding battery. The evaluation may include: detecting a positive deviation of the deviation value relative to a predetermined sixth reference deviation value within a predetermined lower voltage sub-range of a voltage range including voltage measurements of the battery blocks, the positive deviation generally increasing as the voltage value decreases.

[0060] The method may include: when a positive deviation is detected, detecting a potential abnormal state of the battery block, which is a potential safety-related state.

[0061] This increased positive deviation in the lower voltage range can indicate an increase in overvoltage in the battery cell. This could be caused by unwanted, partially reversible lithium plating appearing in the respective battery cell.

[0062] In one embodiment, the mapping is a mapping from current values ​​to deviation values, wherein the evaluation includes: determining a zero-current deviation value corresponding to the value of a linear function at zero current, the linear function having the best fit to the mapping. The evaluation may include: detecting a potential abnormal state of the battery cell, which is a potential safety-related state, when the absolute value of the zero-current deviation value exceeds a threshold.

[0063] The zero current deviation value indicates the magnitude of the battery pack's self-discharge. In particular, when the absolute value of the zero current deviation exceeds a threshold, the battery pack is highly likely to have a high-impedance internal short circuit, which poses a potential hazard. Preferably, the threshold is less than 20 mV. The threshold could be, for example, 10 mV.

[0064] For example, a linear function can be fitted to a mapping, and the value of the linear function at zero current can be determined.

[0065] The method may include: determining the slope of a linear function that best fits the mapping, wherein a potential anomalous state of the battery cell is detected when the absolute value of the slope exceeds a threshold. The slope corresponds to the relative ohmic impedance of the corresponding battery cell.

[0066] One or more of the evaluations described in this paper can be combined, that is, the evaluations can be performed in parallel.

[0067] In any of the above embodiments, the method may include one or more of the following features: This method can be implemented by a computer.

[0068] The first, second, third, fourth, fifth, sixth and / or seventh reference deviation values ​​can be the corresponding first, second, third, fourth, fifth, sixth and / or seventh thresholds.

[0069] As described above, the steps of determining the mapping and evaluating the determined mapping can be repeated for at least one second time frame.

[0070] This method may include: determining whether the degree of deviation increases over (monitoring) time. This method may also include: determining whether the degree of deviation remains generally the same over (monitoring) time.

[0071] The method may include: detecting a potential abnormal state of the battery cell as the degree of deviation increases over (monitoring) time, the potential abnormal state being a potential safety-related state. The method may also include: detecting a potential abnormal state of the battery cell as the degree of deviation remains generally constant over (monitoring) time, the potential abnormal state being a state reflecting a manufacturing defect.

[0072] This method may include: determining whether the degree of positive deviation and / or negative deviation increases over (monitoring) time. This method may also include: determining whether the degree of positive deviation and / or negative deviation remains generally the same over (monitoring) time.

[0073] This method may include detecting a potential anomalous state of the battery cell as the degree of positive deviation and / or negative deviation increases over (monitoring) time. This potential anomalous state is a potential safety-related state. In particular, this could allow for the detection of situations where the battery cell is undergoing a rapid aging process that could lead to thermal runaway.

[0074] The method may include: detecting a potential abnormal state of the battery block that reflects a manufacturing defect when it is determined that the degree of positive deviation and / or the degree of negative deviation remains generally the same over (monitoring) time.

[0075] In aspects of the present invention, a battery monitoring system is provided, comprising means for performing the steps of the methods described herein. In at least one embodiment, the system includes computing means for receiving and processing voltage measurement results or voltage measurement results and current measurement results. The system may include means for receiving and / or calculating reference deviation values. The system may include means for receiving and / or calculating reference mappings. Attached Figure Description

[0076] Preferred embodiments of the invention will now be described with reference to the accompanying drawings, in which: Figure 1 This is a schematic diagram of a method and system for monitoring the behavior of multiple battery blocks connected in series in a battery; Figure 2 a) to Figure 2 d) is a graph showing the mapping of voltage values ​​to deviation values ​​for multiple battery cells connected in series in a battery; Figure 3 a) to Figure 3 d) is a graph showing a series of mappings from the voltage values ​​of multiple battery cells connected in series in the battery to the deviation values ​​during the monitoring period; Figure 4 This is a schematic diagram of the steps involved in a method for monitoring the behavior of multiple battery blocks connected in series in a battery. Figure 5 This is a schematic diagram of a method for monitoring the behavior of multiple battery cells connected in series in a battery; and Figure 6 a) and Figure 6 b) is a graph showing the mapping of voltage values ​​to deviation values ​​for multiple battery cells connected in series in a battery.

[0077] Figure 1 A method and system 100 for monitoring the behavior of multiple battery blocks b1, ..., bn connected in series in a battery is schematically illustrated for detecting a potential abnormal state of one of the multiple battery blocks b1, ..., bn. The battery may be part of a battery storage device.

[0078] For multiple time points t0, t -1 t -2 For each time point in ..., provide the voltage measurement result U for each of the multiple battery blocks b1, ..., bn measured at that time point. b1 ... U bn For example, measurements can be taken every 5 minutes within the first time frame T1 of, for example, 28 days.

[0079] For the first time frame T1, perform the following operations: For multiple time points t0, t1 belonging to the first time frame T1 -1 t -2 For each time point in the series b1, ..., bn, calculate the voltage measurement result U for each of the multiple battery blocks b1, ..., bn. b1 ... U bn The median value M is the average value. Furthermore, the deviation value ΔU of the battery cells is calculated. b1 ... ΔU bn Deviation value ΔU b1 ... ΔU bn This refers to the voltage measurement result U of the battery pack at the corresponding time point. b1 ... U bn The voltage measurement results U of multiple battery blocks b1, ..., bn b1 ... U bn The average voltage deviation M.

[0080] For each of the multiple battery blocks b1, ..., bn and for the first time frame T1, determine the voltage values ​​U1, ..., Un. z To the deviation values ​​ΔU1, ..., ΔU z Mapping 10. Specifically, for voltage values ​​U1, ..., U... z For each voltage value, the deviation value of the battery cell at that voltage value is evaluated, and the extreme values ​​of these deviation values ​​are assigned to the voltage value (i.e., the voltage value is mapped to the corresponding extreme value). The extreme value is the deviation value with the largest absolute value among these deviation values.

[0081] For example, for U b1 ΔU b1 It has already been calculated (it has already occurred); for example, if U b1 The voltage value is equal to ΔU3 = 4.0V, and if ΔU b1 For multiple time points t0, t1 belonging to the first time frame T1 -1 t -2 The maximum deviation value ΔU of ... b1 And it has already appeared at the voltage value ΔU3, then ΔU b1 It will be assigned to the voltage value ΔU3.

[0082] In other words, for the battery pack, the voltage values ​​U1, ..., U... z Each voltage value in the calculation is assigned an extreme value of the deviation values ​​of the battery cell calculated for the corresponding time point, at which the voltage measurement result or current measurement result of the battery cell corresponding to the voltage value is measured, the corresponding time point belonging to the first time frame T1.

[0083] existFigure 1 The lower right part shows a diagram of mapping 10 for multiple battery blocks b1, ..., bn.

[0084] For each of the multiple battery blocks b1, ..., bn, the determined mapping 10 is evaluated to detect potential abnormal states of the battery block. The determined mapping 10 is evaluated relative to at least one reference deviation value 12, 14 (shown as a vertical line in the figure). Specifically, as... Figure 1 As shown in the figure, including voltage measurement results U b1 ... U bn and voltage values ​​U1, ..., U z The negative deviation 16 of the detection deviation value relative to the first reference deviation value 14 in the predetermined higher voltage sub-range of the voltage range.

[0085] The steps of determining mapping 10 and evaluating the determined mapping 10 are repeated for multiple second time frames T2, and it is determined whether the observed negative deviation 16 increases with monitoring time (i.e., the observed negative deviation 16 generally increases with overlapping time frames T1, T2, ...). If this is the case, a potential abnormal state of the battery block is detected, which is a potential safety-related state; the battery block may be affected by undesirable lithium plating.

[0086] For comparison, Figure 2 a) shows a graph mapping voltage values ​​to deviation values ​​when no negative deviation 16 was observed within the indicated voltage range.

[0087] Figure 2 (b) A similar diagram showing the mapping from voltage value to deviation value is presented. In this case, within a predetermined higher voltage sub-range of the voltage range including the voltage measurement results of the battery pack, a positive deviation 22 (within the upper box) of the detection deviation value relative to a predetermined second reference deviation value (corresponding to the left boundary of the upper box) is detected. As schematically shown by the dotted line, the positive deviation 22 generally increases with increasing voltage value. Furthermore, within a predetermined lower voltage sub-range of the voltage range, a negative deviation 24 (within the lower box) of the detection deviation value relative to a predetermined third reference deviation value (corresponding to the right boundary of the lower box) is detected. As schematically shown by the dotted line, the negative deviation 24 generally increases with decreasing voltage value.

[0088] Figure 2c) shows another similar diagram illustrating the mapping from voltage values ​​to deviation values. In this case, the determined mapping for each of the plurality of battery blocks b1, ..., bn is evaluated to determine whether at least one first mapping and at least one second mapping in the mappings show a corresponding deviation relative to zero deviation (e.g., exceeding reference deviation values ​​in the form of positive and negative threshold deviation values, respectively). This diagram shows the case where the deviation of at least one first mapping is symmetrical to the deviation of at least one second mapping overall with respect to the sign of the deviation values ​​(i.e., they are mirror-symmetric with respect to the value ΔU = 0mV). In this case, a potential abnormal state of the corresponding battery block is detected. Thus, asynchronous behavior of the battery block or battery cell can be detected.

[0089] Figure 2 d) shows another similar diagram illustrating the mapping from voltage values ​​to deviation values. In this case, within a predetermined higher voltage sub-range of the voltage range including the voltage measurement results of the battery pack, the detection deviation value shows a negative deviation 26 relative to a predetermined fourth reference deviation value (corresponding to the right boundary of the upper box). As schematically shown by the dotted lines, the negative deviation generally increases with increasing voltage values. Furthermore, within a predetermined lower voltage sub-range of the voltage range, the detection deviation value shows a positive deviation 28 relative to a predetermined fifth reference deviation value (corresponding to the left boundary of the lower box). As schematically shown by the dotted lines, the positive deviation generally increases with decreasing voltage values.

[0090] Figure 3 a) to Figure 3 d) shows a series of similar diagrams illustrating the mapping from voltage values ​​to deviation values. The steps of determining mapping 10 and evaluating the determined mapping 10 are repeated for multiple second time frames T2, and within a predetermined lower voltage subrange of the voltage range including the voltage measurement results of the battery pack, a negative deviation 32 of the deviation value relative to a seventh reference deviation value (corresponding to the right boundary of the inner frame) is detected. For this series, it is determined whether the negative deviation generally increases with monitoring time (i.e., the observed negative deviation 32 generally increases with overlapping time frames T1, T2, ...).

[0091] Figure 4 The steps of another method for monitoring the behavior of multiple battery blocks b1, ..., bn connected in series in a battery are schematically illustrated. The steps preceding the determination of mapping 10 are similar to those in the previous steps. Figure 1 The method is described herein and will not be repeated here. In step 46, before evaluating mapping 10, each determined mapping 10 is scaled based on reference mapping 40. Reference mapping 40 is obtained based on the corresponding mapping of the corresponding battery block of the corresponding battery 42. Specifically, this is achieved by calculating the corresponding deviation value ΔU of the corresponding battery block of the corresponding battery 42. b1 ... ΔU bnThe average value is used to obtain a reference map. Evaluating the scaled map 10 includes detecting a positive deviation 44 of the deviation value relative to a predetermined sixth reference deviation value within a predetermined lower voltage sub-range of the voltage range including the voltage measurements of the battery cell. As schematically shown by the dotted lines, the positive deviation generally increases as the voltage value decreases. Therefore, a continuously increasing overvoltage of the battery cell, which may be caused by undesirable, partially reversible lithium plating, can be detected.

[0092] Figure 5 and Figure 6 a) and Figure 6 (b) Schematarily illustrates the steps of another method for monitoring the behavior of multiple battery blocks b1, ..., bn connected in series in a battery. This method is similar to... Figure 1 The method; the differences are described below. The main difference is that mapping 50 represents the current values ​​I1, ..., I... z To the deviation values ​​ΔU1, ..., ΔU z The mapping.

[0093] For each of the multiple battery blocks b1, ..., bn and for the first time frame T1, determine the current values ​​I1, ..., In. z To the deviation values ​​ΔU1, ..., ΔU z The mapping. Specifically, for current values ​​I1, ..., I... z For each current value, the deviation value of the battery cell at that current value is evaluated (measured for battery cells connected in series), and the extreme values ​​of these deviation values ​​are assigned to the current value (i.e., the current value is mapped to the corresponding extreme value). The extreme value is the deviation value with the largest absolute value among these deviation values.

[0094] Figure 6 a) A mapping 50 is shown for multiple battery blocks b1, ..., bn in a normal state. Each mapping corresponds to a linear function whose slope indicates the ohmic resistance of the battery block.

[0095] Figure 6 b) illustrates the mapping 50 for multiple battery blocks b1, ..., bn under the condition that a potential safety-related state is detected as follows. For illustrative purposes, the mapping 50 for one of the battery blocks is indicated by a dashed line 62, which has a (negative) minimum at zero current. A linear function 64 is determined to have the best fit for the mapping 50. The linear function 64 in... Figure 6 (b) is schematically shown. A zero-current deviation value 66 corresponding to the value of the linear function 64 at the zero-current value is determined. When the absolute value of the zero-current deviation value 66 of the battery cell exceeds a threshold, a potential abnormal state of the battery cell is detected, which is a potential safety-related state.

Claims

1. A method of monitoring the behavior of a plurality of battery blocks (bl,..., bn) connected in series in a battery for detecting a potential abnormal state of one of the plurality of battery blocks (bl,..., bn), the method comprising: For each of a plurality of time points (t0, t -1 , t -2 ,...), a voltage measurement (U b1 ,..., U bn ) of each of the plurality of battery blocks (b1,..., bn) measured at said time point is provided; for each of the plurality of time points (t0, t -1 , t -2 ,...), and for each of the plurality of battery blocks (b1,..., bn), a deviation value (AU b1 ,..., AU bn ; AQ b1 ,..., AQ bn ) of the battery block is calculated, wherein the deviation value is a voltage deviation of the voltage measurement of the battery block with respect to an average value (M) of the voltage measurements (U b1 ,..., U bn ) of the plurality of battery blocks (b1,..., bn), or a charge deviation of the battery block corresponding to the voltage deviation; for each of the plurality of battery blocks (bl,..., bn) and for a first time frame (Tl), determining a mapping (10) of voltage values (Ul,..., U z ) or current values (Il,..., I z ) to deviation values (AUl,..., AU z ), wherein to each of the voltage values (Ul,..., U z ) or to each of the current values (Il,..., I z ) is assigned an extreme value of those deviation values of the battery block which have been calculated for a respective point in time at which a voltage measurement or a current measurement of the battery block corresponding to the voltage value or the current value, respectively, has been measured, the respective point in time belonging to the first time frame (Tl); and for each of the plurality of battery blocks (bl,..., bn), evaluating the determined mapping (10) for detecting a potential abnormal state of the battery block.

2. The method of claim 1, wherein, The average value (M) of the voltage measurements (U b1 ,..., U bn ) of the plurality of battery blocks (b1,..., bn) is a median value of the voltage measurements of the plurality of battery blocks.

3. The method according to any of the preceding claims, wherein, The evaluation comprises evaluating the determined mapping (10) with respect to at least one reference deviation value (12; 14), wherein the at least one reference deviation value (12; 14) is at least one predetermined reference deviation value, or wherein the at least one reference deviation value is obtained based on mappings of other blocks of the plurality of battery blocks (bl,..., bn), or wherein the at least one reference deviation value is obtained based on corresponding mappings of corresponding battery blocks of a corresponding battery.

4. The method according to any of the preceding claims, wherein, The evaluation comprises evaluating the determined mapping with respect to at least one reference mapping (40), wherein the at least one reference mapping is a predetermined reference mapping, or wherein the at least one reference mapping comprises mappings of other blocks of the plurality of battery blocks, or wherein the at least one reference mapping (40) is obtained based on corresponding mappings of corresponding battery blocks of a corresponding battery (42).

5. The method according to any one of the preceding claims, wherein, The potential abnormal state of the battery block is a potential safety-relevant state and / or a state reflecting a manufacturing defect.

6. The method according to any of the preceding claims 1 to 5, wherein The mapping (10) is a mapping of voltage values (U1,..., U z ) to deviation values (ΔU1,..., ΔU z ), wherein the steps of determining a mapping (10) and evaluating the determined mapping (10) are repeated for at least one second time frame (T2), wherein the evaluation comprises detecting a negative deviation (16) of the deviation value with respect to a first reference deviation value (14) in a predetermined higher voltage sub-range of a voltage range comprising voltage measurements of the battery block, and determining whether the negative deviation (16) increases over the monitoring time.

7. The method according to any of the preceding claims 1 to 5, wherein, The mapping (10) is a mapping of voltage values (U1,..., U z ) to deviation values (ΔU1,..., ΔU z ), wherein the evaluation comprises: detecting a positive deviation (22) of the deviation value with respect to a predetermined second reference deviation value in a predetermined higher voltage sub-range of a voltage range comprising voltage measurements of the battery block, the positive deviation (22) generally increasing with increasing voltage values; and detecting a negative deviation (24) of the deviation value with respect to a predetermined third reference deviation value in a predetermined lower voltage sub-range of the voltage range comprising voltage measurements of the battery block, the negative deviation (24) generally increasing with decreasing voltage values.

8. The method according to any of the preceding claims 1 to 5, wherein, The mapping (10) is the voltage value (U1, ..., U...). z ) to deviation values ​​(ΔU1, ..., ΔU z The method includes: evaluating a determined mapping for each of the plurality of battery blocks (b1, ..., bn) to determine whether at least one first mapping and at least one second mapping in the mapping show a corresponding deviation relative to zero, wherein the deviation of the at least one first mapping is generally symmetrical with respect to the sign of the deviation of the at least one second mapping in the mapping, and if so, detecting a potential abnormal state of the corresponding battery block.

9. The method according to any of the preceding claims 1 to 5, wherein The mapping (10) is a mapping of voltage values (U1,..., U z ) to deviation values (ΔU1,..., ΔU z ), wherein the evaluation comprises: detecting a negative deviation (26) of the deviation value with respect to a predetermined fourth reference deviation value in a predetermined higher voltage sub-range of a voltage range comprising voltage measurements of the battery block, the negative deviation generally increasing with increasing voltage values; and In a predetermined lower voltage sub-range of the voltage range comprising the voltage measurement of the battery block, a positive deviation of the deviation values from a predetermined fifth reference deviation value is detected (28), which positive deviation generally increases with a decrease of the voltage values.

10. The method according to any of the preceding claims 1 to 5, wherein The mapping (10) is a mapping of voltage values (U1,..., U z ) to deviation values (ΔU1,..., ΔU z ), wherein the steps of determining a mapping (10) and evaluating the determined mapping (10) are repeated for at least one second time frame (T2), wherein the evaluation comprises: in a predetermined lower voltage sub-range of the voltage range comprising the voltage measurement of the battery block, detecting a negative deviation of the deviation values from a seventh reference deviation value (32); and determining whether the negative deviation increases over the monitoring time.

11. The method according to any of the preceding claims 1 to 5, wherein The mapping (10) is a mapping of voltage values (U1,..., U z ) to deviation values (ΔU1,..., ΔU z ), wherein the method comprises: scaling (46) and / or adjusting the determined mapping (10) based on a reference mapping (40) prior to the step of evaluating the mapping (10), wherein the reference mapping (40) is obtained based on a corresponding mapping of a corresponding battery block of a corresponding battery (42), wherein the evaluation comprises: in a predetermined lower voltage sub-range of the voltage range comprising the voltage measurement of the battery block, detecting a positive deviation of the deviation values from a predetermined sixth reference deviation value (44), which positive deviation generally increases with a decrease of the voltage values.

12. The method according to any of the preceding claims 1 to 5, wherein, The mapping (50) is a mapping of current values (I1,..., I z ) to deviation values (ΔU1,..., ΔU z ), wherein the evaluation comprises: determining a zero current deviation value (66) corresponding to a value of a linear function (64) at a zero current value, the linear function (64) having a best fit to the mapping (50), wherein a potential abnormal state of the battery block is detected when an absolute value of the zero current deviation value (66) exceeds a threshold value, the potential abnormal state being a potential safety relevant state.

13. A battery monitoring system (100), the system comprising means for performing the steps of the method according to any of claims 1 to 12.

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