Battery pack health monitoring method, device, computer equipment and storage medium

Abstract

The present invention relates to a battery pack health monitoring method, device, computer equipment and storage medium. The method comprises monitoring the temperature of each battery in the battery pack to obtain original monitoring data; at a monitoring time point, calculating the first average temperature of the battery pack, and calculating the second average temperature of the monitored battery subgroup according to a preset sequence; calculating the ratio of the second average temperature to the first average temperature; and judging whether the ratio is greater than the corresponding preset threshold value Z. i ; If yes, the monitored battery subgroup is listed as the battery subgroup to be evaluated, and the specified temperature data of each battery to be evaluated in the battery subgroup to be evaluated is obtained; the specified temperature data is subjected to time differential processing respectively; and it is determined whether each differential curve contains a preset lifting feature respectively; if yes, the battery containing the preset lifting feature is listed as a healthy defective battery, and a battery health defect reminder is issued. The present invention can realize timely monitoring of the occurrence of internal micro short circuits in single cells in a battery pack.

Description

Technical Field

[0001] The present invention relates to the technical field of data processing, and in particular to a battery pack health monitoring method, device, computer equipment and storage medium. Background Art

[0002] The development of battery technology has made great progress in recent decades. The energy density and cycle life of batteries have been significantly improved, and they have been gradually widely used in electric vehicles, portable electronic devices, energy storage and other fields. With the continuous evolution of battery technology and the continuous expansion of application scenarios, people have higher and higher requirements for the health of batteries during use. Among them, battery short circuit is an important factor affecting battery health. Unlike factors that slowly affect battery health, such as battery capacity decay and internal resistance increase, battery short circuit may bring rapid and serious thermal runaway consequences. Battery short circuit may be caused by external damage, overcharge, over discharge, failure of internal battery materials or manufacturing defects. Short circuit can cause battery overheating, gas release, and even explosion and fire, posing a serious threat to personal safety and property. When a battery short circuit occurs seriously, its internal pressure, temperature, voltage, etc. will change very significantly, and it is easy to distinguish that the battery is already in a seriously unhealthy state, but at this time the battery may be close to the edge of thermal runaway, and the timeliness of the battery health status warning cannot be guaranteed. Therefore, with the development of battery technology, in terms of battery pack health monitoring, early monitoring of battery short circuit has become crucial. When a battery has an internal short circuit, its temperature and other parameters will change to a certain extent, but the change may not be obvious. Due to the complexity of the battery itself, many factors (such as ambient temperature, battery contact, etc.) may cause temperature fluctuations. If an early warning is issued for a small fluctuation, it may cause too many misjudgments, which will affect the user's trust in the early warning signal issued by the battery monitoring system. Therefore, the battery monitoring system usually does not issue an early warning for a small fluctuation. This makes the early monitoring of the internal short circuit of the battery very difficult. Summary of the invention

[0003] The main purpose of the present invention is to provide a battery pack health monitoring method, device, computer equipment and storage medium, aiming to solve the problem of difficulty in early monitoring of internal short circuit of the battery in the prior art.

[0004] To achieve the above object, the present invention provides a battery pack health monitoring method, comprising the following steps:

[0005] Monitor the temperature of each battery in the battery pack at a preset frequency, and record the battery coordinates and battery temperature of each battery at each monitoring time point to obtain original monitoring data; wherein the battery pack is divided into a plurality of battery subgroups, and each of the battery subgroups includes a plurality of batteries;

[0006] At a monitoring time point, calculating a first average temperature of the battery group, selecting a battery subgroup from the plurality of battery subgroups as a monitoring battery subgroup in a preset order, and calculating a second average temperature of the monitoring battery subgroup;

[0007] calculating a ratio of the second average temperature to the first average temperature;

[0008] Determine whether the ratio is greater than the corresponding preset threshold Z i , where i is the i-th battery subgroup;

[0009] If yes, the monitored battery subgroup is listed as a battery subgroup to be evaluated, and the specified temperature data of each battery to be evaluated in the battery subgroup to be evaluated is obtained;

[0010] Performing time differentiation processing on the designated temperature data of each battery to be evaluated, respectively, to obtain a differential curve of dT / dt versus t, wherein T is the battery temperature and t is the time length;

[0011] Determining whether the differential curve of each battery to be evaluated contains a preset lifting feature;

[0012] If so, the battery containing the preset lifting feature is listed as a health defect battery, and a battery health defect reminder is issued.

[0013] Furthermore, the step of monitoring the temperature of each battery in the battery pack at a preset frequency includes:

[0014] Monitoring the use status of each battery in the battery pack, wherein the use status is selected from constant current charging, constant current discharging, static and other states;

[0015] Determining whether all batteries in the battery pack are in the same preset use state, wherein the preset use state is selected from one of constant current charging, constant current discharging or static;

[0016] If so, the temperature of each battery in the battery pack is monitored at a preset frequency.

[0017] Furthermore, the determination of whether the ratio is greater than the corresponding preset threshold Z i In the step, the preset threshold Z i The setting methods include:

[0018] Calculate the initial preset threshold Z0 corresponding to each battery subgroup i , Z0 i =(R / m) / (R i / n), where R is the initial total internal resistance of the battery pack, R iis the total internal resistance of the i-th battery subgroup, i is a natural number greater than 0, m is the number of batteries in the battery group, and n is the number of batteries in the battery subgroup;

[0019] Determine whether each battery subgroup is listed as a battery subgroup to be evaluated;

[0020] If not, then Z0 i As the preset threshold Z i ;

[0021] If so, get Z from historical data a i , where Z a i is the ratio when the battery subgroup is most recently listed as a battery subgroup to be evaluated and the differential curve of each battery to be evaluated in the battery subgroup to be evaluated does not contain a preset lifting feature, and Z a i As the preset threshold Z i .

[0022] Further, the step of obtaining the specified temperature data of each battery to be evaluated in the battery subgroup to be evaluated includes:

[0023] From the charge and discharge process data of the battery pack no more than three times before the current time, determine whether there is process data of the battery pack being discharged completely and left to stand for more than a first preset time before entering constant current charging;

[0024] If so, the original monitoring data collected during the second preset time period from the start of constant current charging of each battery to be evaluated in the battery subgroup to be evaluated in the process data is used as the designated temperature data.

[0025] Further, the step of obtaining the specified temperature data of each battery to be evaluated in the battery subgroup to be evaluated includes:

[0026] From the charge and discharge process data of the battery pack no more than three times before the current time, determine whether there is process data of the battery pack being discharged completely and left to stand for more than a first preset time before entering constant current charging;

[0027] If not, when the battery group is in an idle state, the battery subgroup to be evaluated is discharged, and the discharged electricity is charged into the battery subgroup that does not need to be evaluated via the battery balancing system;

[0028] After the battery subgroup to be evaluated is completely discharged and has been left to stand for a first preset time, the battery balancing system uses a preset current to charge the battery subgroup to be evaluated from the battery subgroup that does not need to be evaluated, and collects the battery coordinates and battery temperature of each battery to be evaluated in the battery subgroup to be evaluated at a preset frequency, which are used as the designated temperature data.

[0029] Furthermore, in the step of determining whether the differential curve of each battery to be evaluated contains a preset lifting feature, the preset lifting feature is a transition curve connecting two gentle lines, and the inclination of the transition curve is greater than the inclination of the two gentle lines.

[0030] Furthermore, the battery subgroups are allocated according to positions, and a preset number of batteries with close positions are used as a group of battery subgroups. The step of respectively determining whether the differential curve of each battery to be evaluated contains a preset lifting feature includes:

[0031] Determining whether the battery subgroup to be evaluated includes a plurality of batteries to be evaluated that have transition curves, wherein the transition curve is a curve connecting two gentle lines, and a slope of the transition curve is greater than a slope of the two gentle lines;

[0032] If so, determining whether the plurality of batteries to be evaluated that contain transition curves are located adjacent to each other according to the battery coordinates of the plurality of batteries to be evaluated that contain transition curves;

[0033] If so, it is determined that the battery to be evaluated that first appears the transition curve contains the preset lifting feature.

[0034] The present invention also provides a battery pack health monitoring device, comprising:

[0035] A temperature monitoring module is used to monitor the temperature of each battery in the battery pack at a preset frequency, and record the battery coordinates and battery temperature of each battery at each monitoring time point to obtain original monitoring data; wherein the battery pack is divided into a plurality of battery subgroups, and each of the battery subgroups includes a plurality of batteries;

[0036] A first calculation module is used to calculate a first average temperature of the battery group at a monitoring time point, and select a battery subgroup from the plurality of battery subgroups as a monitoring battery subgroup in a preset order, and calculate a second average temperature of the monitoring battery subgroup;

[0037] a second calculation module, configured to calculate a ratio of the second average temperature to the first average temperature;

[0038] The first judgment module is used to judge whether the ratio is greater than the corresponding preset threshold Z i, where i is the i-th battery subgroup;

[0039] A data acquisition module is used to obtain a value if the ratio is greater than the corresponding preset threshold value Z. i , then the monitored battery subgroup is listed as a battery subgroup to be evaluated, and the specified temperature data of each battery to be evaluated in the battery subgroup to be evaluated is obtained;

[0040] A differential calculation module, used for performing time differential processing on the specified temperature data of each battery to be evaluated, to obtain a differential curve of dT / dt versus t, where T is the battery temperature and t is the time;

[0041] A second judgment module is used to judge whether the differential curve of each battery to be evaluated contains a preset lifting feature;

[0042] The defect determination module is used to classify the battery containing the preset lifting feature as a healthy defective battery if it contains the preset lifting feature, and issue a battery health defect reminder.

[0043] The present invention also provides a computer device, comprising a memory and a processor, wherein the memory stores a computer program, and the processor implements the steps of any of the above-mentioned battery pack health monitoring methods when executing the computer program.

[0044] The present invention also provides a computer-readable storage medium having a computer program stored thereon, and when the computer program is executed by a processor, the steps of any of the above-mentioned battery pack health monitoring methods are implemented.

[0045] The present invention provides a battery pack health monitoring method, which monitors the temperature of each battery in the battery pack at a preset frequency and records the original monitoring data; then, at a monitoring time point, calculates the first average temperature of the battery pack, selects a battery subgroup from the plurality of battery subgroups as a monitoring battery subgroup in a preset order, calculates the second average temperature of the monitoring battery subgroup, and calculates the ratio of the second average temperature to the first average temperature; if the ratio is greater than the corresponding preset threshold value Z i, then the monitored battery subgroup is listed as a battery subgroup to be evaluated for further detailed evaluation, and the specified temperature data of each battery to be evaluated in the battery subgroup to be evaluated is obtained; the specified temperature data of each battery to be evaluated is differentiated by time to obtain the differential curve of dT / dt to t, where T is the battery temperature and t is the duration; then it is determined whether the differential curve of each battery to be evaluated contains a preset lifting feature; the battery containing the preset lifting feature is listed as a healthy defect battery, and a battery health defect reminder is issued. By performing block-based temperature monitoring on the battery group and performing differential processing on the specified temperature data of the battery subgroup with increased temperature, the health status of each battery is carefully evaluated, so that timely monitoring of the internal micro-short circuit of the single battery in the battery group can be achieved without causing excessive burden on the data processing of the battery management system and interfering with the user's use. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 is a schematic diagram of a battery pack health monitoring method according to an embodiment of the present invention;

[0047] Figure 2 is a structural block diagram of a battery pack health monitoring device according to an embodiment of the present invention;

[0048] Figure 3 It is a schematic block diagram of the structure of a computer device according to an embodiment of the present invention.

[0049] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0050] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0051] Reference Figure 1 , an embodiment of the present invention discloses a battery pack health monitoring method, comprising the following steps:

[0052] S1. Monitoring the temperature of each battery in the battery pack at a preset frequency, and recording the battery coordinates and battery temperature of each battery at each monitoring time point to obtain original monitoring data; wherein the battery pack is divided into a plurality of battery subgroups, and each of the battery subgroups includes a plurality of batteries;

[0053] S2. At a monitoring time point, calculating a first average temperature of the battery group, and selecting a battery subgroup from the plurality of battery subgroups as a monitoring battery subgroup in a preset order, and calculating a second average temperature of the monitoring battery subgroup;

[0054] S3, calculating the ratio of the second average temperature to the first average temperature;

[0055] S4. Determine whether the ratio is greater than the corresponding preset threshold Z i , where i is the i-th battery subgroup;

[0056] S5. If yes, list the monitored battery subgroup as a battery subgroup to be evaluated, and obtain designated temperature data of each battery to be evaluated in the battery subgroup to be evaluated;

[0057] S6, performing time differentiation processing on the designated temperature data of each battery to be evaluated, to obtain a differential curve of dT / dt versus t, where T is the battery temperature and t is the time;

[0058] S7, determining whether the differential curve of each battery to be evaluated contains a preset lifting feature;

[0059] S8. If yes, the battery having the preset lifting feature is listed as a battery with health defects, and a battery health defect reminder is issued.

[0060] In an embodiment of the present invention, the battery pack health monitoring method can be executed by a battery management system (BMS). The present invention mainly monitors the health of the battery pack to timely monitor the occurrence of internal micro short circuits in the single cells in the battery pack, wherein micro short circuit means that the internal short circuit point of the battery is small, the battery can still be used normally, but there is a small leakage current.

[0061] The above step S1 involves the process of monitoring the temperature of each battery in the battery pack and recording the original monitoring data. Among them, the battery temperature monitoring at a preset frequency is that the system monitors the temperature of each battery in the battery pack according to a preset time interval, and the temperature collected is usually the external shell temperature of the battery cell. The preset frequency is a frequency set according to a rule preset manually. The temperature is collected by the battery management system (BMS), and the preset frequency of collecting the temperature can be set according to the specific battery type, application scenario and other requirements. Specifically, the preset frequency of this embodiment can be a frequency of collecting once every few seconds. At each monitoring time point, the battery coordinates and corresponding battery temperature of each battery are recorded, and these records can constitute the original monitoring data. At the same time, the battery pack is divided into a plurality of battery subgroups, each of which includes a plurality of batteries. The allocation of battery subgroups is manually pre-set in the battery management system, and the number of batteries in each battery subgroup is the same. Specifically, the allocation rule can be to group several batteries with close positions according to the position of the battery; or to group several batteries with close initial internal resistance or capacity according to the initial performance of the battery. Through the above monitoring and recording process, the battery management system obtains the original monitoring data, including the temperature conditions of each battery at different time points and the coordinate information of the battery.

[0062] The above step S2 involves calculating the first average temperature of the battery pack, and selecting a battery subgroup to calculate the second average temperature at a monitoring time point. The battery management system collects battery temperature at a frequency of several seconds and accumulates a large amount of data. The high-frequency processing of data requires a high computing power of the battery management system, which creates a burden on the operation of the battery management system. In this step S2, at a monitoring time point, a battery subgroup is selected to calculate the second average temperature, rather than calculating all battery subgroups separately, which can effectively reduce the data processing volume of the battery management system. The above preset order is an order pre-arranged manually, for example, it can be in the order of the battery subgroup numbers.

[0063] The above step S3 involves calculating the ratio of a monitored battery subgroup to the average temperature of the entire battery group at a monitoring time point. It can be understood that after a period of time, the ratio of each battery subgroup in the battery group to the average temperature of the entire battery group can be calculated, that is, the monitoring of each battery subgroup can be completed. For the first or second average temperature, the factors affecting its change are ambient temperature, charge and discharge current value, charge and discharge time, average internal resistance, and leakage current, among which the ambient temperature, charge and discharge current value, and charge and discharge time have synchronous effects on the entire battery group and a single battery subgroup. Therefore, by calculating the ratio of the two, the effects of ambient temperature, charge and discharge current value, and charge and discharge time can be offset. The change in the ratio of the two can reflect the change in average internal resistance and leakage current. Usually, when the batteries in the battery subgroup are in a healthy state, the above ratio should be relatively constant, with slight fluctuations based on a baseline value.

[0064] In the above step S4, for each battery subgroup, there is a corresponding preset threshold Z set according to a preset rule or manually. i For different battery subgroups, the corresponding preset threshold Z i The values ​​can be different.

[0065] In the above step S5, if the temperature of a single cell rises, the temperature increase of the battery subgroup where it is located will be much more significant than the temperature increase of the entire battery group. i , it means that in the monitored battery subgroup, the temperature of at least one battery is higher than its previous temperature, and further detailed evaluation of the monitored battery subgroup is required to determine whether there are healthy defective batteries in it. If the ratio is less than or equal to the preset threshold value Z i , needs to be further compared with the lower threshold. If it is within the preset threshold Z i If the ratio is between the upper and lower thresholds, it indicates that the batteries in the monitored battery subgroup are in a healthy state. If the ratio is lower than the lower threshold, it indicates that the temperature of batteries in other battery subgroups may be significantly increased. When the battery management system monitors other battery subgroups, it can detect abnormal ratios. The above specified temperature data is used for detailed evaluation of individual batteries in subsequent steps.

[0066] In a specific embodiment, the step S5 of acquiring the specified temperature data of each battery to be evaluated in the battery subgroup to be evaluated comprises:

[0067] S501, judging from the charge and discharge process data of the battery pack no more than three times before the current time whether there is process data of the battery pack being discharged completely and left to stand for more than a first preset time before entering constant current charging;

[0068] S502: If yes, use the original monitoring data collected during the second preset time period from the start of constant current charging of each battery to be evaluated in the battery subgroup to be evaluated in the process data as the designated temperature data.

[0069] This embodiment involves searching for data that meets the requirements in the data of the last three charge and discharge processes. If so, the data can be directly retrieved for fine evaluation of a single battery in subsequent steps, which does not affect the current use of the battery and improves the user's experience. In the above step S501, the first preset duration is a manually preset duration. Those skilled in the art can set it according to the type, material, volume, etc. of the battery so that the battery can reach a stable state when it is discharged and left to stand for the first preset duration, for example, it can be tens of minutes to several hours. In the above step S502, the second preset duration is a preset duration. Specifically, it can be set according to the type, material, volume, etc. of the battery. The second preset duration can be tens of minutes to several hours, at least greater than the heat conduction duration from the center point of the battery to the shell. The heat conduction duration can be calculated by the battery heat conduction model in the prior art, such as a heat conduction equation model, a three-dimensional heat conduction model, a particle-scale heat conduction model, etc. The present invention does not repeat these models here. By collecting the specified temperature data that meets the above conditions, it can be ensured that the temperature changes caused by the internal micro-short circuit are monitored.

[0070] In another specific embodiment, the step S5 of acquiring the specified temperature data of each battery to be evaluated in the battery subgroup to be evaluated comprises:

[0071] S511, judging from the charge and discharge process data of the battery pack no more than three times before the current time whether there is process data of the battery pack being discharged completely and left to stand for more than a first preset time before entering constant current charging;

[0072] S512: If not, when the battery group is in an idle state, the battery subgroup to be evaluated is discharged, and the discharged electricity is charged into the battery subgroup that does not need to be evaluated via the battery balancing system;

[0073] S513: After the battery subgroup to be evaluated is completely discharged and has been left to stand for a first preset time, the battery balancing system uses a preset current to charge the battery subgroup to be evaluated from the battery subgroup that does not need to be evaluated, and collects the battery coordinates and battery temperature of each battery to be evaluated in the battery subgroup to be evaluated at a preset frequency, and uses them as the designated temperature data.

[0074] This embodiment involves searching for data that meets the requirements in the data of the last three charge and discharge processes. If not, a program is set to collect specified temperature data when the battery pack is in an idle state. In the above step S511, the first preset duration is a manually preset duration. Those skilled in the art can set it according to the type, material, volume, etc. of the battery so that the battery can reach a stable state when it is discharged and left to stand for the first preset duration, for example, it can be tens of minutes to several hours. In the above step S512, the idle state is a state in which the battery pack still has power and does not need to be charged, and the battery pack has not received a discharge instruction at that time. When the battery pack is in an idle state, the specified temperature data of the battery subgroup to be evaluated is collected without affecting the user's experience. Through the battery balancing system, the power of the battery subgroup to be evaluated is discharged and charged into other battery subgroups. A group can be selected from multiple other battery subgroups at will, or a group of battery subgroups can be manually determined in advance to receive the power of the battery subgroup to be evaluated. In the above step S513, the battery subgroup to be evaluated is discharged and left to stand for the first preset duration so that the temperature of the battery subgroup to be evaluated is stable. The battery balancing system is used to charge the discharged electricity released in step S513 back into the battery subgroup to be evaluated. At this time, the battery coordinates and battery temperature of each battery to be evaluated in the battery subgroup to be evaluated are collected as the designated temperature data for further detailed evaluation. The above-mentioned preset current is a pre-set current, which can be set according to the capacity, material type, etc. of the specific battery pack. Preferably, a small rate current of less than 0.5C is set. Using the method of this embodiment, the designated temperature data is collected in the idle state of the battery, and the power is transferred between the two battery subgroups through the battery balancing system. After the designated temperature data collection is completed, the battery pack returns to the state before the data collection, which does not affect the user's continued use, and the user experience is good.

[0075] In the above step S6, by performing differential processing on the specified temperature data and obtaining the differential curve of dT / dt to t, the change in temperature per unit time of the battery during use can be accurately evaluated. Since the battery itself has a certain internal resistance, when current passes through, the battery temperature will gradually rise at a first speed. If an internal micro-short circuit occurs in the battery at the same time, a leakage current will be generated, and the heat generated by the leakage current will accumulate from the internal short circuit point and slowly conduct outward. It can only be conducted to the surface of the battery shell after a certain conduction time. When the heat caused by the internal micro-short circuit is conducted to the surface of the shell, it can be measured that the battery temperature rises faster, and then rises at a second speed, which is higher than the first speed. If an internal micro-short circuit occurs in the battery, by making a differential curve of dT / dt to t, the change trend of the change in temperature per unit time can be more clearly shown, which is convenient for the battery management system to capture the subtle changes in the battery temperature and identify that the subtle changes are caused by the internal short circuit, so as to timely discover the early internal short circuit for effective battery health monitoring.

[0076] In the above step S7, by identifying the differential curve, it is determined whether the differential curve contains the preset lifting feature.

[0077] In a specific embodiment, the preset lifting feature is a transition curve connecting two gentle lines, and the inclination of the transition curve is greater than the inclination of the two gentle lines. The slope range of the gentle lines can be defined according to historical data, and the slope range of the transition curve exceeds a preset slope threshold, which can also be defined according to historical data. Specifically, the following method can be used to automatically identify the above-mentioned preset lifting features: calculate the slope at each point on the differential curve, and the slope is obtained by calculating the ratio of the height difference between two adjacent points to the horizontal distance; for each point, calculate the average slope of several points before and after it; when it is detected that the slope change amplitude exceeds the preset slope threshold, it can be considered that the transition curve is found, wherein the preset slope threshold can be set according to actual conditions or according to statistical data, for example, the preset slope threshold is defined according to the slope range of the gentle lines; when the transition curve is identified, it can be further verified whether its inclination is greater than the inclination of the two gentle lines. By performing linear fitting on the transition curve, its slope is obtained, and then compared with the slopes of the gentle lines on both sides. If the verification result shows that the curve meets the conditions of the preset lifting feature, it can be determined that the preset lifting feature has been found.

[0078] In a specific embodiment, the battery subgroups are allocated according to positions, and a preset number of batteries that are close in position are taken as a group of battery subgroups. The step S7 of respectively determining whether the differential curve of each battery to be evaluated contains a preset lifting feature includes:

[0079] S701, determining whether the battery subgroup to be evaluated includes a plurality of batteries to be evaluated that have transition curves, wherein the transition curve is a curve connecting two gentle lines, and a slope of the transition curve is greater than a slope of the two gentle lines;

[0080] S702: If yes, determine whether the multiple batteries to be evaluated that have transition curves are adjacent to each other according to the battery coordinates of the multiple batteries to be evaluated that have transition curves;

[0081] S703: If yes, determine that the battery to be evaluated that has the transition curve appearing earliest contains the preset lifting feature.

[0082] This embodiment is used to solve the following problem: when multiple batteries located close to each other are used as a battery subgroup, when a healthy defective battery appears in a battery subgroup, it is possible that after its own temperature rises, the heat is further transferred to the surrounding batteries, causing the temperature of the surrounding batteries to also rise, and the characteristics of the transition curve may also appear in the differential curve of the surrounding batteries.

[0083] In step S701, the slope range of the gentle line can be defined according to historical data, and the slope range of the transition curve exceeds the preset slope threshold, and the preset slope threshold can also be defined according to historical data. Specifically, the following method can be used to automatically identify the above-mentioned preset lifting feature: calculate the slope at each point on the differential curve, and the slope is obtained by calculating the ratio of the height difference between two adjacent points to the horizontal distance; for each point, calculate the average slope of several points before and after it; when it is detected that the slope change exceeds the preset slope threshold, it can be considered that the transition curve is found, wherein the preset slope threshold can be set according to actual conditions or according to statistical data, for example, the preset slope threshold is defined according to the slope range of the gentle line; when the transition curve is identified, it can be further verified whether its inclination is greater than the inclination of the two gentle lines, by linearly fitting the transition curve, obtaining its slope, and then comparing it with the slopes of the gentle lines on both sides, if the verification result shows that the curve meets the conditions of the preset lifting feature, it can be determined that the preset lifting feature is found.

[0084] In step S702, by comparing the battery coordinates of multiple batteries to be evaluated that contain transition curves, it is determined whether the multiple batteries to be evaluated that contain transition curves are adjacent to each other. If they are adjacent, step S703 is entered to select the battery to be evaluated that first appears the transition curve feature, and the transition curve it contains is used as the preset lifting feature. The surrounding batteries of the battery are not temporarily determined to contain the preset lifting feature. Since in the subsequent steps, the battery containing the preset lifting feature is determined to have a health defect of an internal micro-short circuit, the user will replace or repair it, that is, remove the battery with the health defect. The surrounding batteries will continue to monitor whether there is a temperature abnormality in the next round of health monitoring. If there is still a temperature abnormality, it will be evaluated again; if there is no temperature abnormality, it indicates that the appearance of the transition curve in the differential curve in this evaluation is affected by the health defect battery next to it. If they are not adjacent, the non-adjacent batteries to be evaluated will be determined to contain the preset lifting feature.

[0085] In the above step S8, for the battery with the preset lifting feature, it can be determined that it has a health defect of internal micro-short circuit. Although thermal runaway has not yet occurred, the short circuit defect will become more and more obvious with the continuous use of the battery. Therefore, a battery health defect reminder is issued to the user during the micro-short circuit period to remind the user of the battery defect as early as possible, leaving the user time for repair or replacement.

[0086] In one embodiment, the step S1 of monitoring the temperature of each battery in the battery pack at a preset frequency comprises:

[0087] S101, monitoring the use status of each battery in the battery pack, wherein the use status is selected from constant current charging, constant current discharging, static and other states;

[0088] S102, determining whether all batteries in the battery pack are in the same preset use state, wherein the preset use state is selected from one of constant current charging, constant current discharging or static;

[0089] S103: If yes, monitor the temperature of each battery in the battery pack at a preset frequency.

[0090] This embodiment is used to optimize the range of original monitoring data, select a suitable time period to monitor the temperature of the battery pack, and also reduce the data collection and data processing of the battery management system. When the batteries in the battery pack are in the same use state, the average temperature of each battery subgroup and the battery pack has synchronous comparison value. When the battery is in different use states, there are too many external factors affecting the temperature, and it cannot be determined that the temperature change is caused by the battery itself. In the above step S102, the preset use state is one of constant current charging, constant current discharge or static. When the batteries in the battery pack are in the same state of these three preset use states, it means that the external conditions of each battery are consistent, and the external input or output current to the outside is equal, which is suitable for temperature comparison. When the battery is in other states, such as constant voltage charging, pulse charging, etc., the current applied to each battery is inconsistent, which will cause the temperature of each battery to be different, and it does not have the meaning of parallel comparison.

[0091] In a specific embodiment, the determination of whether the ratio is greater than the corresponding preset threshold value Z i In step S4, the preset threshold value Z i The setting methods include:

[0092] S401, calculating the initial preset threshold value Z0 corresponding to each battery subgroup i , Z0 i =(R / m) / (R i / n), where R is the initial total internal resistance of the battery pack, R i is the total internal resistance of the i-th battery subgroup, i is a natural number greater than 0, m is the number of batteries in the battery group, and n is the number of batteries in the battery subgroup;

[0093] S402, determining whether each battery subgroup is listed as a battery subgroup to be evaluated;

[0094] S403, if not, then Z0 i As the preset threshold Z i ;

[0095] S404: If yes, obtain Z from historical data a i , where Z a i is the ratio when the battery subgroup is most recently listed as a battery subgroup to be evaluated and the differential curve of each battery to be evaluated in the battery subgroup to be evaluated does not contain a preset lifting feature, and Z a i As the preset threshold Z i .

[0096] In step S401 of this embodiment, R or Ri The test can be performed by a constant current discharge method well known to those skilled in the art, or by simulation calculation through an equivalent circuit, as well as other feasible methods in the prior art. Specifically, the constant current discharge method is to apply a known load current to the battery pack / battery sub-group for constant current discharge, and then measure the change of the output voltage of the battery pack over time, and calculate the total internal resistance of the battery pack by analyzing the discharge curve. The equivalent circuit method is to simulate the battery pack as an equivalent circuit, obtain the internal resistance of each battery in the battery pack through actual measurement, and then perform circuit analysis to calculate the internal resistance of the battery pack. In step S403, if the battery sub-group is not listed as an over-evaluated battery sub-group, the preset threshold value Z i Using the initial preset threshold Z0 i In step S404, if the battery subgroup has been listed as a battery subgroup to be evaluated, it means that the battery subgroup has had a ratio greater than the preset threshold value Z in previous use. i However, after the differential calculation and evaluation in the subsequent steps, it is found that the batteries in the battery pack have no health defects. The deviation of the ratio may be related to the normal use of the battery, environmental factors, etc., but not to the health defect of micro-short circuit. In this case, Z a i As the new preset threshold Z i , to avoid frequent misjudgments that trigger subsequent differential calculation evaluations.

[0097] Reference Figure 2 The present invention also provides a battery pack health monitoring device, comprising:

[0098] The temperature monitoring module 10 is used to monitor the temperature of each battery in the battery pack at a preset frequency, and record the battery coordinates and battery temperature of each battery at each monitoring time point to obtain original monitoring data; wherein the battery pack is divided into a plurality of battery subgroups, and each of the battery subgroups includes a plurality of batteries;

[0099] A first calculation module 20 is used to calculate a first average temperature of the battery group at a monitoring time point, and select a battery subgroup from the plurality of battery subgroups as a monitoring battery subgroup according to a preset order, and calculate a second average temperature of the monitoring battery subgroup;

[0100] A second calculation module 30, configured to calculate a ratio of the second average temperature to the first average temperature;

[0101] The first judgment module 40 is used to judge whether the ratio is greater than the corresponding preset threshold Z i , where i is the i-th battery subgroup;

[0102] The data acquisition module 50 is used to obtain the value of the ratio if it is greater than the corresponding preset threshold value Z. i, then the monitored battery subgroup is listed as a battery subgroup to be evaluated, and the specified temperature data of each battery to be evaluated in the battery subgroup to be evaluated is obtained;

[0103] A differential calculation module 60 is used to perform time differential processing on the specified temperature data of each battery to be evaluated, and obtain a differential curve of dT / dt versus t, where T is the battery temperature and t is the time length;

[0104] A second judgment module 70, used to judge whether the differential curve of each battery to be evaluated contains a preset lifting feature;

[0105] The defect determination module 80 is used to classify the battery containing the preset lifting feature as a healthy defective battery if it contains the preset lifting feature, and issue a battery health defect reminder.

[0106] In this embodiment, for the specific implementation of each unit in the above-mentioned battery pack health monitoring device, please refer to the content of each corresponding step in the above-mentioned battery pack health monitoring method embodiment, and the present invention will not be repeated here.

[0107] In one embodiment, the temperature monitoring module 10 includes:

[0108] A usage status monitoring submodule, used to monitor the usage status of each battery in the battery pack, wherein the usage status is selected from constant current charging, constant current discharging, static and other states;

[0109] A state judgment submodule, used to judge whether all batteries in the battery pack are in the same preset use state, wherein the preset use state is selected from one of constant current charging, constant current discharging or static;

[0110] The state determination submodule is used to monitor the temperature of each battery in the battery pack at a preset frequency if each battery in the battery pack is in the same preset use state.

[0111] In one embodiment, in the first judgment module 40, the preset threshold value Z i The setting methods include:

[0112] The initial threshold calculation submodule is used to calculate the initial preset threshold Z0 corresponding to each battery subgroup i , Z0 i =(R / m) / (R i / n), where R is the initial total internal resistance of the battery pack, R i is the total internal resistance of the i-th battery subgroup, i is a natural number greater than 0, m is the number of batteries in the battery group, and n is the number of batteries in the battery subgroup;

[0113] The subgroup to be evaluated judgment submodule is used to judge whether each battery subgroup is listed as a battery subgroup to be evaluated;

[0114] The first determination submodule is used to set Z0 if the battery subgroup is not listed as a battery subgroup to be evaluated. i As the preset threshold Z i ;

[0115] The second determination submodule is used to obtain Z from historical data if the battery subgroup is listed as a battery subgroup to be evaluated. a i , where Z a i is the ratio when the battery subgroup is most recently listed as a battery subgroup to be evaluated and the differential curve of each battery to be evaluated in the battery subgroup to be evaluated does not contain a preset lifting feature, and Z a i As the preset threshold Z i .

[0116] In one embodiment, the data acquisition module 50 includes:

[0117] A process data judgment submodule, used to judge whether the process data of the battery pack's charge and discharge process no more than three times from the current state contains process data of the battery pack being discharged completely and left to stand for more than a first preset time before entering constant current charging;

[0118] The first process data determination submodule is used to use the original monitoring data collected from each battery to be evaluated in the battery subgroup to be evaluated during the second preset time period starting from the entry into constant current charging as the designated temperature data if the process data contains process data in which the battery group is discharged completely and left to stand for more than a first preset time period before entering constant current charging.

[0119] In one embodiment, the data acquisition module 50 includes:

[0120] A process data judgment submodule, used to judge whether the process data of the battery pack's charge and discharge process no more than three times from the current state contains process data of the battery pack being discharged completely and left to stand for more than a first preset time before entering constant current charging;

[0121] A second process data determination submodule is configured to discharge the battery subgroup to be evaluated when the battery group is in an idle state, and charge the discharged electricity into the battery subgroup that does not need to be evaluated via the battery balancing system, if there is no process data of the battery group being discharged completely and being left stationary for more than a first preset time before entering constant current charging;

[0122] After the battery subgroup to be evaluated is completely discharged and has been left to stand for a first preset time, the battery balancing system uses a preset current to charge the battery subgroup to be evaluated from the battery subgroup that does not need to be evaluated, and collects the battery coordinates and battery temperature of each battery to be evaluated in the battery subgroup to be evaluated at a preset frequency, which are used as the designated temperature data.

[0123] In one embodiment, in the second judgment module 70, the preset lifting feature is a transition curve connecting two gentle lines, and the inclination of the transition curve is greater than the inclination of the two gentle lines.

[0124] In one embodiment, the battery subgroups are allocated according to positions, and a preset number of batteries that are close to each other are taken as a group of battery subgroups. The second determination module 70 includes:

[0125] The submodule for determining the number of subgroups to be evaluated is used to determine whether the subgroup of batteries to be evaluated contains a plurality of batteries to be evaluated that have a transition curve, wherein the transition curve is a curve connecting two gentle lines, and the inclination of the transition curve is greater than the inclination of the two gentle lines;

[0126] A submodule for determining the position of a subgroup to be evaluated, for determining whether the multiple batteries to be evaluated containing transition curves are adjacent to each other according to the battery coordinates of the multiple batteries to be evaluated containing transition curves if the subgroup to be evaluated contains multiple batteries to be evaluated containing transition curves;

[0127] The preset lifting feature determination submodule is used to determine that the battery to be evaluated that has the transition curve appearing earliest contains the preset lifting feature if the positions are adjacent.

[0128] For the specific implementation of each submodule in the above-mentioned device embodiments, please refer to the corresponding description in the above-mentioned method embodiments, which will not be repeated here.

[0129] Reference Figure 3 In an embodiment of the present invention, a computer device is also provided. The computer device may be a server, and its internal structure may be as follows: Figure 3 As shown. The computer device includes a processor, a memory, a display screen, an input device, a network interface and a database connected through a system bus. Among them, the processor designed by the computer is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program and a database. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The database of the computer device is used to store the corresponding data in this embodiment. The network interface of the computer device is used to communicate with an external terminal through a network connection. When the computer program is executed by the processor, the above method is implemented.

[0130] Those skilled in the art will understand that Figure 3 The structure shown in the figure is merely a block diagram of a portion of the structure related to the solution of the present invention, and does not constitute a limitation on the computer device to which the solution of the present invention is applied.

[0131] An embodiment of the present invention further provides a computer-readable storage medium on which a computer program is stored, and when the computer program is executed by a processor, the above method is implemented. It can be understood that the computer-readable storage medium in this embodiment can be a volatile readable storage medium or a non-volatile readable storage medium.

[0132] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, storage, database or other media provided by the present invention and used in the embodiments may include non-volatile and / or volatile memory. Non-volatile memory may include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM) or flash memory. Volatile memory may include random access memory (RAM) or external cache memory. As an illustration and not limitation, RAM is available in a variety of forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double-speed data rate SDRAM (SSRSDRAM), enhanced SDRAM (ESDRAM), synchronous link (Synchlink) DRAM (SLDRAM), memory bus (Rambus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM.

[0133] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, device, article or method including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, device, article or method. In the absence of further restrictions, an element defined by the sentence "includes a ..." does not exclude the presence of other identical elements in the process, device, article or method including the element.

[0134] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made by using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A battery pack health monitoring method, characterized in that: The following steps are involved: The temperature of each battery in the battery pack is monitored at a preset frequency, and the battery coordinates and the battery temperature of each battery at each monitoring time point are correspondingly recorded to obtain original monitoring data; wherein the battery pack is divided into a plurality of battery subgroups, and each of the battery subgroups includes a plurality of batteries; At a monitoring time point, calculating a first average temperature of the battery group, selecting a battery subgroup from the plurality of battery subgroups as a monitoring battery subgroup in a preset order, and calculating a second average temperature of the monitoring battery subgroup; calculating a ratio of the second average temperature to the first average temperature; Determine whether the ratio is greater than the corresponding preset threshold Z i , where i is the i-th battery subgroup; If yes, the monitored battery subgroup is listed as a battery subgroup to be evaluated, and the specified temperature data of each battery to be evaluated in the battery subgroup to be evaluated is obtained; Performing time differentiation processing on the designated temperature data of each battery to be evaluated, respectively, to obtain a differential curve of dT / dt versus t, wherein T is the battery temperature and t is the time length; Determining whether the differential curve of each battery to be evaluated contains a preset lifting feature; If so, the battery containing the preset lifting feature is listed as a health defect battery, and a battery health defect reminder is issued.

2. The battery pack health monitoring method according to claim 1, characterized in that: The step of monitoring the temperature of each battery in the battery pack at a preset frequency comprises: Monitoring the use status of each battery in the battery pack, wherein the use status is selected from constant current charging, constant current discharging, static and other states; Determining whether all batteries in the battery pack are in the same preset use state, wherein the preset use state is selected from one of constant current charging, constant current discharging or static; If so, the temperature of each battery in the battery pack is monitored at a preset frequency.

3. The battery pack health monitoring method according to claim 1, characterized in that: Determine whether the ratio is greater than the corresponding preset threshold Z i In the step, the preset threshold Z i The setting methods include: Calculate the initial preset threshold Z0 corresponding to each battery subgroup i , Z0 i =(R / m) / (R i / n), where R is the initial total internal resistance of the battery pack, R i is the total internal resistance of the i-th battery subgroup, i is a natural number greater than 0, m is the number of batteries in the battery group, and n is the number of batteries in the battery subgroup; Determine whether each battery subgroup is listed as a battery subgroup to be evaluated; If not, then Z0 i As the preset threshold Z i ; If so, get Z from historical data a i , where Z a i is the ratio when the battery subgroup is most recently listed as a battery subgroup to be evaluated and the differential curve of each battery to be evaluated in the battery subgroup to be evaluated does not contain a preset lifting feature, and Z a i As the preset threshold Z i .

4. The battery pack health monitoring method according to claim 1, characterized in that: The step of obtaining the specified temperature data of each battery to be evaluated in the battery subgroup to be evaluated comprises: From the charge and discharge process data of the battery pack no more than three times before the current time, determine whether there is process data of the battery pack being discharged completely and left to stand for more than a first preset time before entering constant current charging; If so, the original monitoring data collected during the second preset time period from the start of constant current charging of each battery to be evaluated in the battery subgroup to be evaluated in the process data is used as the designated temperature data.

5. The battery pack health monitoring method according to claim 1, characterized in that: The step of obtaining the specified temperature data of each battery to be evaluated in the battery subgroup to be evaluated comprises: From the charge and discharge process data of the battery pack no more than three times before the current time, determine whether there is process data of the battery pack being discharged completely and left to stand for more than a first preset time before entering constant current charging; If not, when the battery group is in an idle state, the battery subgroup to be evaluated is discharged, and the discharged electricity is charged into the battery subgroup that does not need to be evaluated via the battery balancing system; After the battery subgroup to be evaluated is completely discharged and has been left to stand for a first preset time, the battery balancing system uses a preset current to charge the battery subgroup to be evaluated from the battery subgroup that does not need to be evaluated, and collects the battery coordinates and battery temperature of each battery to be evaluated in the battery subgroup to be evaluated at a preset frequency, which are used as the designated temperature data.

6. The battery pack health monitoring method according to claim 1, characterized in that: In the step of determining whether the differential curve of each battery to be evaluated contains a preset lifting feature, the preset lifting feature is a transition curve connecting two gentle lines, and the inclination of the transition curve is greater than the inclination of the two gentle lines.

7. The battery pack health monitoring method according to claim 1, characterized in that: The battery subgroups are allocated according to positions, and a preset number of batteries that are close in position are used as a group of battery subgroups. The step of respectively determining whether the differential curve of each battery to be evaluated contains a preset lifting feature includes: Determining whether the battery subgroup to be evaluated includes a plurality of batteries to be evaluated that have transition curves, wherein the transition curve is a curve connecting two gentle lines, and a slope of the transition curve is greater than a slope of the two gentle lines; If so, determining whether the plurality of batteries to be evaluated that contain transition curves are located adjacent to each other according to the battery coordinates of the plurality of batteries to be evaluated that contain transition curves; If so, it is determined that the battery to be evaluated that first appears the transition curve contains the preset lifting feature.

8. A battery pack health monitoring device, characterized in that: include: A temperature monitoring module is used to monitor the temperature of each battery in the battery pack at a preset frequency, and record the battery coordinates and battery temperature of each battery at each monitoring time point to obtain original monitoring data; wherein the battery pack is divided into a plurality of battery subgroups, and each of the battery subgroups includes a plurality of batteries; A first calculation module is used to calculate a first average temperature of the battery group at a monitoring time point, and select a battery subgroup from the plurality of battery subgroups as a monitoring battery subgroup in a preset order, and calculate a second average temperature of the monitoring battery subgroup; a second calculation module, configured to calculate a ratio of the second average temperature to the first average temperature; The first judgment module is used to judge whether the ratio is greater than the corresponding preset threshold Z i , where i is the i-th battery subgroup; A data acquisition module is used to obtain a value if the ratio is greater than the corresponding preset threshold value Z. i , then the monitored battery subgroup is listed as a battery subgroup to be evaluated, and the specified temperature data of each battery to be evaluated in the battery subgroup to be evaluated is obtained; A differential calculation module, used for performing time differential processing on the specified temperature data of each battery to be evaluated, to obtain a differential curve of dT / dt versus t, where T is the battery temperature and t is the time; A second judgment module is used to judge whether the differential curve of each battery to be evaluated contains a preset lifting feature; The defect determination module is used to classify the battery containing the preset lifting feature as a healthy defective battery if it contains the preset lifting feature, and issue a battery health defect reminder.

9. A computer device comprising a memory and a processor, wherein a computer program is stored in the memory, wherein: When the processor executes the computer program, the steps of the battery pack health monitoring method according to any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the battery pack health monitoring method according to any one of claims 1 to 7 are implemented.

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