Self-discharge determination method for battery module and computer system
By obtaining the charge state characteristic amount of the battery cell and the voltage increment at the charging cut-off time during the charging process, combining the average and difference values of multiple battery cells, the self-discharge risk of lithium iron phosphate batteries is accurately identified, and lithium iron phosphate is solved The problem of self-discharge detection of batteries improves battery safety and service life.
Patent Information
- Application Number
- CN202310768942.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-06-26
- Publication Date
- 2024-12-27
AI Technical Summary
The self-discharge detection of lithium iron phosphate system batteries is difficult to identify through the OCV-SOC curve, resulting in difficult monitoring of self-discharge abnormalities, affecting the health and safety of the battery.
By obtaining the charge state characteristic amount of the battery cell and the voltage increment at the charging cut-off time during the charging process, combining the average and difference of multiple battery cells, we can judge whether there is a risk of self-discharge in the battery cell, and eliminate the capacity difference caused by aging. to achieve accurate self-discharge monitoring.
It improves the accuracy of battery self-discharge identification, ensures the safety of battery use and extends the battery life.
Smart Images
Figure CN119199535A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of vehicle batteries, and more specifically to a method and device for determining self-discharge of a battery module, a computer system, and a storage medium. Background Art
[0002] With the gradual popularization of new energy vehicles, people have put forward higher and higher requirements for the actual endurance provided by on-board batteries. Self-discharge, as one of the important factors affecting the capacity retention ability of battery modules, needs to be monitored in real time to determine the health of the battery modules. When abnormal self-discharge occurs, the battery module should be discovered in time to avoid causing a bad experience to users or even safety hazards. Common self-discharge is due to the formation of a local current loop due to the large particle size inside the battery. When the particle size gradually expands to pierce the diaphragm, it will directly form an internal short circuit, thereby accelerating the aging of the battery cell and causing high-risk safety issues such as thermal runaway of the battery cell.
[0003] Compared with ternary system batteries, the open circuit voltage (OCV)-state of charge (SOC) curve of lithium iron phosphate system batteries is relatively flat (see attached Figure 1 ), usually a certain OCV value can be mapped to a wide range of SOC values, which makes it difficult to identify the abnormal SOC reduction caused by self-discharge through the change of OCV. Therefore, self-discharge detection of batteries with a flat OCV-SOC curve, such as lithium iron phosphate system batteries, has always been a difficult problem in the industry. Summary of the invention
[0004] In order to solve or at least alleviate one or more of the above problems, the present invention proposes a method and device for determining self-discharge of a battery module, a computer system, and a storage medium, which can improve the accuracy and efficiency of identifying battery self-discharge, ensure the safety of battery use and extend the battery life.
[0005] According to a first aspect of the present invention, there is provided a method for determining self-discharge of a battery module, wherein the battery module comprises a plurality of battery cells, and the method comprises: charging the battery module until a charging cut-off time; during the charging process, obtaining a charge state characteristic quantity of each battery cell in a first interval, wherein the charge state characteristic quantity represents the charge state when the battery cell capacity increment in the first interval is at a minimum value; obtaining a voltage increment of each battery cell at the charging cut-off time; and judging whether self-discharge occurs in each battery cell based on the charge state characteristic quantity of each battery cell and the voltage increment at the charging cut-off time.
[0006] As an alternative or supplement to the above scheme, in a method according to an embodiment of the present invention, the charge state characteristic quantity is obtained according to the following steps: during the charging process, based on the voltage and charging current of each battery cell at different times, the corresponding relationship between the capacity increment and the charge state of each battery cell is determined; based on the corresponding relationship between the capacity increment and the charge state of each battery cell, the charge state characteristic quantity of each battery cell in the first interval is obtained; the voltage increment at the charging cut-off time is obtained according to the following steps: during the charging process, based on the voltage and charging current of each battery cell at different times, the corresponding relationship between the voltage increment and time of each battery cell is determined; based on the corresponding relationship between the voltage increment and time of each battery cell, the voltage increment of each battery cell at the charging cut-off time is obtained.
[0007] As an alternative or supplement to the above scheme, in a method according to an embodiment of the present invention, the acquisition of the charge state characteristic quantity of each battery cell in the first interval includes: for each battery cell, determining the minimum value of the capacity increment in the charge state interval corresponding to the first interval, and determining the charge state when the capacity increment is equal to the minimum value as the charge state characteristic quantity of the battery cell. As an alternative or supplement to the above scheme, in a method according to an embodiment of the present invention, the multiple battery cells include a first battery cell, and judging whether each battery cell has self-discharged based on the charge state characteristic quantity of each battery cell and the voltage increment at the charging cutoff time includes: judging whether there is a risk of self-discharge based on the charge state characteristic quantity of the first battery cell; and if there is a risk of self-discharge in the first battery cell, judging whether self-discharge has occurred based on the voltage increment of the first battery cell at the charging cutoff time.
[0008] As an alternative or supplement to the above scheme, in a method according to an embodiment of the present invention, the multiple battery cells include a first battery cell, and the judging whether self-discharging occurs in each battery cell based on the charge state characteristic quantity of each battery cell and the voltage increment at the charging cut-off time includes: determining an average value of the charge state characteristic quantity of the multiple battery cells; if the difference between the charge state characteristic quantity of the first battery cell and the average value is greater than a first threshold value, judging that the first battery cell has a risk of self-discharging; determining the median and the absolute median difference of the voltage increments at the charging cut-off time of the multiple battery cells; calculating the difference between the median and twice the absolute median difference; if the voltage increment at the charging cut-off time of the first battery cell is less than the difference, judging that self-discharging occurs in the first battery cell.
[0009] As an alternative or supplement to the above scheme, in a method according to an embodiment of the present invention, the multiple battery cells include a first battery cell, and the method further includes: if it is determined that the first battery cell has self-discharged, the battery module is charged a second time; during the two charging processes, the self-discharge rate of the first battery cell is determined based on the charge state characteristic quantity of the first battery cell and the average value of the charge state characteristic quantities of the multiple battery cells.
[0010] As an alternative or supplement to the above scheme, in a method according to an embodiment of the present invention, the self-discharge rate of the first battery cell is determined based on the charge state characteristic quantity of the first battery cell and the average value of the charge state characteristic quantities of the multiple battery cells during the two charging processes, including: determining a first difference between the charge state characteristic quantity of the first battery cell and a first average value during the first charging process, wherein the first average value is the average value of the charge state characteristic quantities of the multiple battery cells during the first charging process; determining a second difference between the charge state characteristic quantity of the first battery cell and a second average value during the second charging process, wherein the second average value is the average value of the charge state characteristic quantities of the multiple battery cells during the second charging process; and determining the self-discharge rate of the first battery cell during the interval between two charges based on a third difference between the second difference and the first difference.
[0011] According to a second aspect of the present invention, a computer system is provided, the system comprising: a memory configured to store instructions; and a processor coupled to the memory, configured to execute the instructions so as to perform any one of the methods described in the first aspect of the present invention.
[0012] According to a third aspect of the present invention, there is provided a self-discharge determination device for a battery module, wherein the battery module comprises a plurality of battery cells, and the device comprises: a charging unit, configured to charge the battery module until the voltage of one battery cell in the battery module reaches a cut-off voltage or the voltages of at least two battery cells simultaneously reach the cut-off voltage; a processing unit, configured to: determine, based on the voltage and charging current of each battery cell during the charging process, a correspondence between a capacity increment and a charge state and a correspondence between a voltage increment and time of each battery cell during the charging process; and determine whether self-discharge occurs in each battery cell based on a charge state characteristic quantity at the minimum value of the capacity increment when the charge state is in a first interval and a voltage increment at the charging cut-off time.
[0013] According to a fourth aspect of the present invention, there is provided a computer storage medium, the computer storage medium comprising instructions, the instructions executing any one of the methods according to the first aspect of the present invention when run.
[0014] The self-discharge determination scheme for battery modules according to one or more embodiments of the present invention can accurately detect the position of the battery cell where self-discharge occurs by monitoring the charge state characteristic quantity of each battery cell in the battery module and the voltage increment at the charging cut-off time during the charging process, thereby realizing accurate and reliable monitoring of the self-discharge of each battery cell in the battery module. In addition, the self-discharge determination scheme for battery modules according to one or more embodiments of the present invention simultaneously utilizes the charge state characteristic quantity of each battery cell in the first interval and the voltage increment at the charging cut-off time to determine whether self-discharge occurs, so that the self-discharge misjudgment caused by the difference in battery cell capacity due to battery cell aging can be eliminated, thereby improving the accuracy of battery self-discharge identification, ensuring the safety of battery use and extending the battery life. BRIEF DESCRIPTION OF THE DRAWINGS
[0015] The above and / or other aspects and advantages of the present invention will become clearer and easier to understand through the following description of various aspects in conjunction with the accompanying drawings, in which the same or similar units are represented by the same reference numerals. In the accompanying drawings:
[0016] Figure 1 The OCV-SOC curves of lithium iron phosphate system batteries and ternary system batteries are shown;
[0017] Figure 2 A flow chart showing a self-discharge determination method 20 for a battery module according to one or more embodiments of the present invention; and
[0018] Figure 3 FIG. 4 is a schematic block diagram of an apparatus 30 for determining self-discharge of a battery module according to one or more embodiments of the present invention. DETAILED DESCRIPTION
[0019] The following will further describe in detail the self-discharge determination method and device for battery modules, computer systems, and storage media of the present invention in conjunction with the accompanying drawings. It should be noted that the description of the following specific embodiments is merely exemplary in nature and is not intended to limit the disclosed technology or the application and use of the disclosed technology. In addition, it is not intended to be bound by any express or implied theory presented in the aforementioned technical field, background technology, or the following specific embodiments.
[0020] In the following detailed description of the embodiments, many specific details are set forth in order to provide a more thorough understanding of the disclosed technology. However, it is apparent to one of ordinary skill in the art that the disclosed technology can be practiced without these specific details. In other instances, well-known features are not described in detail to avoid unnecessarily complicating the description.
[0021] Terms such as "comprising" and "including" indicate that in addition to the units and steps directly and clearly stated in the specification, the technical solution of the present invention does not exclude the situation of having other units and steps that are not directly or clearly stated. Terms such as "first" and "second" do not indicate the order of units in terms of time, space, size, etc., but are only used to distinguish between units.
[0022] Referring to the accompanying drawings, Figure 2 FIG. 2 is a flow chart of a self-discharge determination method 20 for a battery module according to one or more embodiments of the present invention.
[0023] like Figure 2 As shown, in step S210, the battery module is charged until the charging cut-off time.
[0024] Wherein, the battery module includes a plurality of battery cells, and the plurality of battery cells are two or more battery cells. Preferably, the battery module is a battery pack with good battery cell consistency. Exemplarily, the plurality of battery cells have the same model and have similar initial charge states (for example, the initial charge states of each battery cell are in the range of 25% to 35%), thereby excluding battery modules with poor consistency and obvious defects. The above-mentioned battery cells can be selected from lithium iron phosphate system batteries, ternary system batteries or any other system batteries. The above-mentioned battery cells can include columnar battery cells (such as cylindrical, hexagonal battery cells, etc.), square shell battery cells and soft pack battery cells and battery cells of other shapes.
[0025] The charging cut-off time is the time when the battery module stops charging. In a specific embodiment, when at least one battery cell in the battery module reaches its cut-off voltage, the battery module stops charging, and this time is recorded as the charging cut-off time of the battery module.
[0026] Optionally, the battery module is charged with a constant charging current. The charging current is preferably a small current with high stability, for example, less than or equal to 1 / 3C. C is the current of the nominal capacity of the battery. In addition, the collected charging current value can be used to determine whether the charging current is stable. For example, when the ratio of the difference between the maximum and minimum values of the charging current to the mean of the charging current value is less than a preset value, the charging current is determined to be a stable current. Performing the various steps of the self-discharge determination method under the premise of a stable small current can improve the accuracy of self-discharge identification.
[0027] In step S220, during the charging process of step S210, a charge state characteristic quantity of each battery cell in the first interval is obtained, wherein the charge state characteristic quantity represents the charge state when the battery cell capacity increment is at a minimum value in the first interval.
[0028] The first interval is a preset time interval, and the start time, end time and interval length of the first interval can be set according to requirements. Exemplarily, the first interval is related to the characteristics of the battery cell material.
[0029] Exemplarily, obtaining the charge state characteristic quantity of each battery cell in the first interval during the charging process includes obtaining the corresponding relationship between the capacity increment and the charge state of each battery cell (for example, a curve or function relationship), wherein the capacity increment dQ / dV of the battery cell represents the capacity change of the battery cell within a constant voltage interval. For lithium batteries, there are usually one or more voltage platforms, which means that a small fluctuation in the voltage of the lithium battery within the platform range corresponds to a larger capacity, which is reflected as a characteristic point of dQ / dV, and each characteristic point (for example, a valley, peak, maximum or minimum value) can represent an electrochemical reaction, and the characteristic point position represents the phase change point of the positive and negative electrode materials of the battery cell. After in-depth research, the inventors of the present application found that by obtaining the charge state characteristic quantity of each battery cell in the first interval, it can be determined whether each battery cell has a self-discharge risk. Optionally, the above-mentioned charge state characteristic quantity can be obtained specifically according to the following steps S221-222.
[0030] In step S221, during the charging process, the corresponding relationship between the capacity increment and the charge state of each battery cell is determined based on the voltage and charging current of each battery cell at different times. Exemplarily, the corresponding relationship between the voltage V of each battery cell during the charging process and the time t (for example, the Vt curve) and the corresponding relationship between the charging current I and the time t (for example, the It curve) can be collected and recorded during the charging process, and the corresponding relationship between the capacity Q of each battery cell and the time t (for example, the Qt curve) can be obtained by integrating the charging current I in ampere hours. Exemplarily, the capacity Q of the battery cell can be calculated by the following formula (1):
[0031]
[0032] Where I is the charging current, t is the charging time, and Q0 is the initial capacity of the battery cell. Next, the dQ / dV-SOC correspondence (for example, dQ / dV-SOC curve) of the capacity increment dQ / dV of each battery cell relative to the state of charge SOC can be obtained based on the Vt correspondence and Qt correspondence of each battery cell, where the state of charge of the battery cell is the ratio between the current capacity Q of the battery cell and the rated capacity of the battery cell.
[0033] In step S222, the charge state characteristic quantity of each battery cell in the first interval is obtained according to the correspondence between the capacity increment and the charge state of each battery cell. As described above, the first interval is a preset time interval and is related to the material characteristics of the battery cell. In one example, when the battery cell is a lithium iron phosphate system, the charging time interval corresponding to 50% SOC to 90% SOC can be set as the first interval. Correspondingly, step S222 includes: for each battery cell, determining the minimum value of the capacity increment in the charge state interval corresponding to the first interval, and determining the charge state when the capacity increment is equal to the minimum value as the charge state characteristic quantity of the battery cell. In one example, when the battery cell is a lithium iron phosphate system, the point with the smallest dQ / dV value within 50% SOC to 90% SOC is selected as a feature point, and the charge state of the feature point is the charge state characteristic quantity (for example, 63%).
[0034] In step S230, during the charging process of step S210, the voltage increment of each battery cell at the charging cut-off time is obtained. Exemplarily, obtaining the voltage increment of each battery cell at the charging cut-off time includes obtaining the corresponding relationship between the voltage increment and time (for example, a curve or a functional relationship), wherein the voltage increment dV / dQ of the battery cell characterizes the voltage change of the battery cell within a constant capacity interval. Similarly, the characteristic points of dV / dQ (for example, valley values, peak values, maximum values, or minimum values) can also represent the phase change points of the positive and negative electrode materials of the battery cell. After in-depth research, the inventors of the present application found that by obtaining the voltage increment of each battery cell at the charging cut-off time, it can be determined whether the battery cell is at risk of reduced capacity due to battery cell aging.
[0035] Optionally, the voltage increment at the charging cut-off moment may be obtained specifically according to the following steps S231-232.
[0036] In step S231, during the charging process, based on the voltage and charging current of each battery cell at different times, the corresponding relationship between the voltage increment of each battery cell and time is determined. Exemplarily, the corresponding relationship between the voltage V of each battery cell during the charging process and time t (for example, Vt curve) and the corresponding relationship between the charging current I and time t (for example, It curve) can be collected and recorded during the charging process, and the corresponding relationship between the capacity Q of each battery cell and time t (for example, Qt curve) can be obtained by integrating the charging current I in ampere hours (for example, according to the above formula 1). Next, based on the corresponding relationship between the Vt and Qt of each battery cell, the corresponding relationship between the voltage increment dV / dQ of each battery cell and time t (for example, dV / dQ-t curve) is obtained. In step S232, according to the corresponding relationship between the voltage increment of each battery cell and time, the voltage increment at the charging cut-off moment of each battery cell is obtained.
[0037] In step S240, it is determined whether each battery cell has self-discharged according to the charge state characteristic quantity of each battery cell and the voltage increment at the charging cut-off time. As described above, since the charge state characteristic quantity of the battery cell can be used to determine whether the battery cell has a risk of self-discharge, and the voltage increment at the charging cut-off time of the battery cell can be used to determine whether the battery cell has a risk of capacity reduction due to battery cell aging, the present invention creatively combines the above-mentioned charge state characteristic quantity of the battery cell and the characteristic quantity of the voltage increment (that is, the voltage increment at the charging cut-off time) to achieve accurate identification of self-discharge.
[0038] Specifically, after a large number of experiments, the inventors of the present application found that the difference between the minimum position of the capacity increment dQ / dV of the battery cell in a specific charge state interval and the average position of the minimum capacity increment dQ / dV of the entire battery module can characterize the self-discharge risk of the battery cell. Further, it can be understood that, according to the charging characteristics of the battery cell, the voltage will rise sharply when the battery cell is close to the full charge state, and the voltage increment dV / dQ at this time is large. If a battery cell has a lower capacity than other batteries in the battery module due to aging, the battery cell will be fully charged first during the charging process, and at the charging cut-off time, the voltage increment dV / dQ of the battery cell will be significantly higher than the voltage increment dV / dQ of other batteries. Therefore, the voltage increment dV / dQ at the charging cut-off time can be determined as the characteristic quantity of the voltage increment, and it can be used to judge whether there is a possibility that the battery cell has a reduced capacity due to battery cell aging.
[0039] Optionally, after determining the charge state characteristic quantity and the voltage increment at the charging cut-off time, in step S240, first determine whether the battery cell has a risk of self-discharge based on the charge state characteristic quantity of the battery cell; if it is determined that the battery cell has a risk of self-discharge, then further determine whether the battery cell has a risk of capacity reduction due to battery cell aging based on the voltage increment at the charging cut-off time of the battery cell; if the battery cell has a risk of self-discharge and does not have a risk of capacity reduction due to battery cell aging, then determine that the battery cell has self-discharged.
[0040] In one example, if the battery module includes a first battery cell, a second battery cell, and a third battery cell, the following steps can be performed to determine whether the first battery cell has a risk of self-discharge: determine the average value of the charge state characteristic quantity of multiple battery cells; if the difference between the charge state characteristic quantity of the first battery cell and the average value is greater than the first threshold value, it is determined that the first battery cell has a risk of self-discharge. Exemplarily, the first threshold value can be set to 4%. For example, if the charge state characteristic quantity of the first battery cell is 63%, the charge state characteristic quantity of the second battery cell is 57%, and the charge state characteristic quantity of the third battery cell is 54%, then the average value of the charge state characteristic quantity of the battery module is 58%. Since the difference between the charge state characteristic quantity of the first battery cell of 63% and the average value of 58% is 5%, and the difference is greater than the first threshold value of 4%, it is determined that the first battery cell has a risk of self-discharge.
[0041] Next, determine whether there is a possibility that the capacity of the first battery cell has decreased due to battery cell aging. Specifically, determine the median and absolute median difference of the voltage increments at the charging cutoff time of multiple battery cells; calculate the difference between the median and twice the absolute median difference; if the voltage increment at the charging cutoff time of the first battery cell is less than the difference, determine that the first battery cell has self-discharged. Exemplarily, the absolute median difference MAD of the voltage increments at the charging cutoff time of multiple battery cells can be calculated by the following formula (2):
[0042]
[0043] in, Indicates the voltage increment at the end of charging of each battery cell. Indicates the median of the voltage increments at the end of charging of multiple cells.
[0044] If the voltage increment of the first battery cell at the end of charging If the following formula (3) is satisfied, it is determined that the cell does not have the risk of capacity reduction due to cell aging, and then it is determined that the first cell has self-discharged:
[0045]
[0046] Optionally, method 20 also includes step S250: if it is determined that the first battery cell has self-discharged, the battery module is charged a second time, and during the two charging processes, the self-discharge rate of the first battery cell is determined based on the charge state characteristic quantity of the first battery cell and the average value of the charge state characteristic quantities of multiple battery cells.
[0047] Exemplarily, in step S250, the first difference between the charge state characteristic quantity of the first battery cell and the first average value during the first charging process (that is, the charging process in step S210) is first determined, wherein the first average value is the average value of the charge state characteristic quantities of multiple battery cells during the first charging process. Next, after a period of time (for example, one month), the battery module is recharged, and the second difference between the charge state characteristic quantity of the first battery cell and the second average value during the secondary charging process is determined, wherein the second average value is the average value of the charge state characteristic quantities of multiple battery cells during the secondary charging process. Continuing with the example above, if the charge state characteristic quantity of the first battery cell during the first charging process is 63% and the average value is 58%, the first difference is 5%; if the charge state characteristic quantity of the first battery cell during the secondary charging process is 70% and the average value is 59%, the second difference is 11%. At this time, the self-discharge rate of the first battery cell during the interval between two charges can be determined based on the third difference between the second difference and the first difference. For example, the self-discharge rate of the first battery cell is equal to the difference between the second difference of 11% and the first difference of 5%, which is 6%, divided by the length of the interval between two charges (1 month). During the charging interval, the self-discharge rate of the first battery cell is 5% SOC per month. Optionally, a recall threshold can also be set. If the self-discharge rate of the first battery cell is greater than or equal to the recall threshold (for example, 4.5% SOC per month), the first battery cell is recalled.
[0048] According to one or more embodiments of the present invention, the method 20 can accurately detect the position of the cell where self-discharge occurs (for example, the first cell) by monitoring the voltage and charging current of each cell in the battery module in real time during the charging process, thereby realizing accurate and reliable monitoring of the self-discharge of each cell in the battery module. In addition, the method 20 can simultaneously use the charge state characteristic quantity of each cell in the first interval and the voltage increment at the charging cut-off time to determine whether self-discharge occurs, so that the self-discharge misjudgment caused by the cell capacity difference caused by cell aging can be eliminated, thereby improving the accuracy of battery self-discharge identification, ensuring the safety of battery use and extending the battery life.
[0049] According to another aspect of the present invention, a device for determining self-discharge of a battery module is provided. Figure 3 As shown, the device 30 includes a charging unit 310 and a processing unit 320. The device 30 can accurately determine whether the battery module self-discharges and can detect the self-discharge rate of the self-discharging battery cell.
[0050] The charging unit 310 is configured to charge the battery module until the charging cut-off time. The processing unit 320 is configured to: during the charging process, obtain the charge state characteristic quantity of each battery cell in the first interval, wherein the charge state characteristic quantity represents the charge state when the battery cell capacity increment in the first interval is less than or equal to the preset value and is at the minimum value; obtain the voltage increment of each battery cell at the charging cut-off time; and determine whether each battery cell has self-discharged based on the charge state characteristic quantity of each battery cell and the voltage increment at the charging cut-off time. For the detailed steps of determining the charge state characteristic quantity and the voltage increment at the charging cut-off time and determining the self-discharge of the battery cell, please refer to the description of steps S220-S240 above, which will not be repeated here.
[0051] Optionally, the processing unit 320 is further configured to: if it is determined that the first battery cell self-discharges, the battery module is charged twice; during the two charging processes, the self-discharge rate of the first battery cell is determined based on the charge state characteristic quantity of the first battery cell and the average value of the charge state characteristic quantities of the plurality of battery cells. The detailed steps for determining the self-discharge rate can be referred to the description of step S250 above, which will not be repeated here.
[0052] According to another aspect of the present invention, a computer system is provided, comprising a memory configured to store instructions; and a processor coupled to the memory, configured to execute the instructions to perform any one of the self-discharge determination methods described above. Exemplarily, the computer system is a battery management system.
[0053] In addition, the present invention can also be implemented as a computer storage medium, in which instructions are stored, and when the instructions are executed by a processor, the processor executes any of the self-discharge determination methods described above. Here, as a computer storage medium, various computer storage media such as disks (e.g., magnetic disks, optical disks, etc.), cards (e.g., memory cards, optical cards, etc.), semiconductor memories (e.g., ROMs, non-volatile memories, etc.), and tapes (e.g., magnetic tapes, cassette tapes, etc.) can be used.
[0054] Where applicable, hardware, software or a combination of hardware and software may be used to implement the various embodiments provided by the present invention. Moreover, where applicable, without departing from the scope of the present invention, the various hardware components and / or software components set forth herein may be combined into composite components comprising software, hardware and / or both. Where applicable, without departing from the scope of the present invention, the various hardware components and / or software components set forth herein may be divided into subcomponents comprising software, hardware or both. In addition, where applicable, it is contemplated that software components may be implemented as hardware components, and vice versa.
[0055] Software according to the present invention (such as program code and / or data) can be stored on one or more computer storage media. It is also contemplated that the software identified herein can be implemented using one or more general or special computers and / or computer systems networked and / or otherwise. Where applicable, the order of the various steps described herein can be changed, combined into composite steps and / or divided into sub-steps to provide the features described herein.
[0056] The embodiments and examples set forth herein are provided to best illustrate embodiments according to the present invention and its specific applications, and thereby enable those skilled in the art to make and use the present invention. However, those skilled in the art will appreciate that the above description and examples are provided for ease of illustration and example only. The description set forth is not intended to cover all aspects of the present invention or to limit the present invention to the precise form disclosed.
Claims
1. A method for determining self-discharge of a battery module, characterized in that: The battery module includes a plurality of battery cells, and the method includes: Charging the battery module until the charging cut-off time; During the charging process, a charge state characteristic quantity of each battery cell in a first interval is obtained, wherein the charge state characteristic quantity represents the charge state when the battery cell capacity increment in the first interval is at a minimum value; Obtaining a voltage increment of each battery cell at the charging cut-off time; Whether self-discharge occurs in each battery cell is determined according to the charge state characteristic quantity of each battery cell and the voltage increment at the charging cut-off time.
2. The method according to claim 1, wherein: The charge state characteristic quantity is obtained according to the following steps: During the charging process, based on the voltage and charging current of each battery cell at different times, the corresponding relationship between the capacity increment and the charge state of each battery cell is determined; Acquire a charge state characteristic quantity of each battery cell in the first interval according to a correspondence between a capacity increment and a charge state of each battery cell; The voltage increment at the charging cut-off time is obtained according to the following steps: During the charging process, based on the voltage and charging current of each battery cell at different times, the corresponding relationship between the voltage increment and time of each battery cell is determined; According to the corresponding relationship between the voltage increment of each battery cell and time, the voltage increment of each battery cell at the charging cut-off moment is obtained.
3. The method according to claim 2, wherein: The acquiring the charge state characteristic quantity of each battery cell in the first interval includes: For each battery cell, a minimum value of a capacity increment in a charge state interval corresponding to the first interval is determined, and the charge state when the capacity increment is equal to the minimum value is determined as a charge state characteristic value of the battery cell.
4. The method according to any one of claims 1 to 3, wherein: The plurality of battery cells include a first battery cell, and judging whether self-discharge occurs in each battery cell according to the charge state characteristic quantity of each battery cell and the voltage increment at the charging cut-off time includes: Determining whether there is a self-discharge risk based on the charge state characteristic quantity of the first battery cell; and If the first battery cell has a risk of self-discharging, whether the first battery cell has self-discharging is determined based on a voltage increment of the first battery cell at the charging cut-off time.
5. The method according to any one of claims 1 to 3, wherein: The plurality of battery cells include a first battery cell, and judging whether self-discharge occurs in each battery cell according to the charge state characteristic quantity of each battery cell and the voltage increment at the charging cut-off time includes: Determining an average value of the charge state characteristic quantities of the plurality of battery cells; If the difference between the charge state characteristic value of the first battery cell and the average value is greater than a first threshold value, it is determined that the first battery cell has a self-discharge risk; If it is determined that the first battery cell has a self-discharge risk, determining the median and the absolute median difference of the voltage increments at the charging cut-off time of the plurality of battery cells; calculating the difference between the median and twice the absolute median difference; If the voltage increment of the first battery cell at the charging cut-off time is smaller than the difference, it is determined that the first battery cell self-discharges.
6. The method according to any one of claims 1 to 3, wherein: The plurality of battery cells include a first battery cell, and the method further includes: If it is determined that the first battery cell has self-discharged, recharging the battery module; During the two charging processes, the self-discharge rate of the first battery cell is determined based on the charge state characteristic quantity of the first battery cell and the average value of the charge state characteristic quantities of the plurality of battery cells.
7. The method according to claim 6, wherein: The method of determining the self-discharge rate of the first battery cell based on the charge state characteristic quantity of the first battery cell and the average value of the charge state characteristic quantities of the plurality of battery cells during the two charging processes includes: Determine a first difference between a charge state characteristic value of the first battery cell and a first average value during the first charging process, wherein the first average value is an average value of the charge state characteristic values of the plurality of battery cells during the first charging process; Determine a second difference between the charge state characteristic quantity of the first battery cell and a second average value during the secondary charging process, wherein the second average value is an average value of the charge state characteristic quantities of the plurality of battery cells during the secondary charging process; and A self-discharge rate of the first battery cell during an interval between two charges is determined based on a third difference between the second difference and the first difference.
8. A computer system, characterized in that: The system comprises: a memory configured to store instructions; and A processor coupled to the memory, configured to execute the instructions so as to perform the method according to any one of claims 1-7.
9. A self-discharge determination device for a battery module, characterized in that: The battery module includes a plurality of battery cells, and the device includes: a charging unit configured to charge the battery module until a charging cut-off time; A processing unit configured to: During the charging process, a charge state characteristic quantity of each battery cell in a first interval is obtained, wherein the charge state characteristic quantity represents the charge state when the battery cell capacity increment in the first interval is at a minimum value; Obtaining a voltage increment of each battery cell at the charging cut-off time; Whether self-discharge occurs in each battery cell is determined according to the charge state characteristic quantity of each battery cell and the voltage increment at the charging cut-off time.
10. A computer storage medium, wherein instructions are stored in the computer storage medium, characterized in that: When the instructions are executed by a processor, the processor is caused to perform the method according to any one of claims 1 to 7.