Abnormal battery cell identification method and energy storage system
By performing equalization operations in energy storage batteries, the process of identifying abnormal cells is simplified, solving the complex and inefficient identification problem in existing technologies. This achieves efficient and low-cost identification of abnormal cells and is suitable for identifying the working status of energy storage batteries.
Patent Information
- Application Number
- CN202511178850.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-21
- Publication Date
- 2025-11-21
AI Technical Summary
In existing technologies, abnormal cell identification methods are complex to operate and require long-term static placement, resulting in low identification efficiency and failing to meet the scheduling needs of energy storage batteries when connected to the grid.
By identifying cells in the energy storage battery that meet preset conditions and performing a balancing operation to make the state of charge of the remaining cells consistent with the target cell, abnormal cells can be identified using the balancing amount of the balancing operation, simplifying the identification process to one that does not require long-term static placement.
It enables efficient identification of abnormal battery cells, simplifies operation steps, reduces identification costs, maintains the working state of energy storage batteries, and improves the versatility of identification.
Smart Images
Figure CN120993250A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of energy storage systems, and particularly relates to an abnormal battery cell identification method and an energy storage system. BACKGROUND
[0002] Energy storage batteries are used to store electrical energy and release electrical energy when needed. A battery cell is the smallest energy storage unit in an energy storage battery, and a single energy storage battery can include thousands of battery cells. In an energy storage battery, the self-discharge phenomenon of the battery cells can cause differences in the capacity of each battery cell, affecting the battery capacity and service life of the energy storage battery. Related technologies can determine the self-discharge rate of the battery cells by calculating the pressure drop, and then determine the abnormal battery cells. However, the traditional calculation method requires the battery cells to be at rest for a long time, so that the current abnormal battery cell identification method is complex to operate, and the long time at rest also leads to low efficiency of identifying abnormal battery cells. SUMMARY
[0003] Embodiments of the present application provide an abnormal battery cell identification method and an energy storage system, which can improve the identification efficiency of abnormal battery cells, simplify the identification steps, and have good versatility, to at least partially solve the above technical problems.
[0004] To achieve the above-mentioned purpose, according to a first aspect of the present application, an abnormal battery cell identification method is provided, comprising: in the case that there is a first battery cell satisfying a first preset condition in an energy storage battery, performing an equalization operation on the remaining battery cells in the energy storage battery except the first battery cell; wherein the SOC of the first battery cell is in a first interval, and the SOC of the remaining battery cells is greater than the maximum value of the first interval; after the equalization operation, if there is a second battery cell in the energy storage battery, and the second battery cell and the first battery cell both include a third battery cell satisfying a second preset condition, then determining the abnormal condition of the third battery cell according to the equalization amount of the equalization operation; wherein the SOC of the second battery cell is in the first interval.
[0005] Optionally, the first battery cell satisfying the first preset condition includes: the number of battery cells of the first battery cell is less than or equal to a first threshold, or the ratio of the number of battery cells of the first battery cell to the total number of battery cells of the energy storage battery is less than or equal to a second threshold.
[0006] Optionally, the third battery cell satisfying the second preset condition includes: a first SOC corresponding to the third battery cell before the equalization operation is greater than a second SOC of the third battery cell after the equalization operation.
[0007] Optionally, the first interval is in a low SOC linear interval in an open-circuit voltage-state-of-charge curve of the battery cell.
[0008] Optionally, the method further comprises: in a case where the battery current value of the energy storage battery is zero for a duration exceeding a first duration, determining an open circuit voltage value according to the cell voltage value of the cell in the energy storage battery, so as to determine the SOC of each cell in the energy storage battery in the open circuit voltage-state of charge curve according to the open circuit voltage value.
[0009] Optionally, the equalization operation on the remaining cells other than the first cell in the energy storage battery comprises: connecting each of the remaining cells to an equalization resistor respectively; and controlling each of the remaining cells to discharge at a preset current, so as to consume the electric quantity of each of the remaining cells through the equalization resistor.
[0010] Optionally, the determination of the abnormal condition of the third cell according to the equalization amount of the equalization operation comprises: in a case where the duration of the equalization operation is a second duration, obtaining a first equalization amount of the equalization operation within the second duration; and in a case where the first equalization amount is greater than a preset equalization threshold, determining that the third cell is abnormal.
[0011] Optionally, the method further comprises: in a case where it is determined that the third cell is abnormal, outputting prompt information.
[0012] According to a second aspect of the present application, an energy storage system is provided, comprising: an energy storage battery module comprising cells; and a control module connected to the energy storage battery module, the control module being configured to perform the abnormal cell identification method provided in the first aspect.
[0013] Optionally, the control module comprises: a collection circuit connected to the energy storage battery module and / or the cells, and an equalization circuit connected to the cells; wherein the collection circuit is configured to collect electrical parameters of the energy storage battery module and / or the cells; and the equalization circuit is configured to perform an equalization operation on the cells.
[0014] In summary, the abnormal cell identification method and the energy storage system provided in the embodiments of the present application perform an equalization operation on the remaining cells other than the first cell in the energy storage battery in a case where the first cell satisfying the first preset condition exists in the energy storage battery; wherein the SOC of the first cell is in a first interval, and the SOC of the remaining cells is greater than the maximum value of the first interval. After the equalization operation on the remaining cells other than the first cell, if a second cell exists in the energy storage battery, and the second cell and the first cell both comprise a third cell satisfying a second preset condition, the abnormal condition of the third cell is determined according to the equalization amount of the equalization operation, wherein the SOC of the second cell is also in the first interval.
[0015] The embodiment of the present application first determines the first battery cell with abnormal risk in the first interval in the energy storage battery, controls all battery cells in the energy storage battery to have the same state of charge through the equalization operation of the remaining battery cells except the first battery cell, and then determines the second battery cell with abnormal risk in the first interval in the energy storage battery after the equalization operation; in the case that the first battery cell and the second battery cell both include the third battery cell, the abnormal state of the third battery cell is determined according to the equalization amount of the equalization operation of the remaining battery cells, and the identification of the abnormal battery cell of the energy storage battery is realized. The embodiment of the present application does not need a complex calculation model or detection device, and the abnormal battery cell identification can be realized through the equalization operation of part of the battery cells in the energy storage battery, which is simple in calculation, low in identification cost, and high in identification efficiency. The abnormal battery cell identification method of the embodiment of the present application does not need to be placed for a long time, and the energy storage battery can remain in the working state, and has strong versatility.
[0016] Other features and advantages of the present application will be described in detail in the following specific embodiments. BRIEF DESCRIPTION OF DRAWINGS
[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiment description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without any creative labor on the basis of these drawings.
[0018] In order to more completely understand the present application and its beneficial effects, the following will be described in conjunction with the drawings, wherein the same reference numerals in the following description represent the same parts.
[0019] Figure 1 is a flowchart of an abnormal battery cell identification method provided by the embodiment of the present application;
[0020] Figure 2 is a schematic diagram of the state of charge of a battery cell provided by the embodiment of the present application;
[0021] Figure 3 is a schematic diagram of the open-circuit voltage-state of charge curve of a battery cell provided by the embodiment of the present application;
[0022] Figure 4 is a schematic diagram of a battery cell equalization circuit provided by the embodiment of the present application;
[0023] Figure 5 is a schematic diagram of the voltage of a battery cell of an energy storage battery provided by the embodiment of the present application;
[0024] Figure 6 is a flowchart of another abnormal battery cell identification method provided by the embodiment of the present application;
[0025] Figure 7 is a structural schematic diagram of an energy storage system provided by an embodiment of the present application;
[0026] Figure 8 is a circuit diagram of a voltage acquisition circuit provided by an embodiment of the present application;
[0027] Figure 9 is a circuit diagram of an AFE chip provided by an embodiment of the present application;
[0028] Figure 10 is a circuit diagram of a current acquisition circuit provided by an embodiment of the present application. DETAILED DESCRIPTION
[0029] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person skilled in the art without creative labor fall within the protection scope of the present application.
[0030] The energy storage battery is a device for storing electric energy in an energy storage system and releasing the stored electric energy when needed. The energy storage battery includes a plurality of battery cells, and the battery cell is the smallest energy storage unit in the energy storage battery. The self-discharge abnormality refers to the phenomenon that the energy of the battery cell is lost significantly faster than the normal level in the case that the energy storage battery is not connected to any load, thereby causing the energy storage battery to be abnormal.
[0031] The self-discharge abnormality of the battery cell can be caused by different reasons, such as manufacturing defects of the battery cell, internal short circuit of the battery cell, environmental influence, physical damage, electrolyte corrosion, etc. Among them, the manufacturing defects of the battery cell include material or process problems that can occur in the production process of the battery cell; the internal short circuit of the battery cell includes an additional current path caused by the internal short circuit of the battery cell, which causes the battery cell to discharge quickly when not in use; the environmental influence includes an increase in the self-discharge rate caused by the battery cell being in a high temperature or excessively low temperature environment; the physical damage includes abnormal self-discharge caused by the battery cell being physically damaged by puncture or impact; and the electrolyte corrosion includes abnormal discharge caused by the battery cell due to leakage or chemical change of the electrolyte.
[0032] The energy storage battery includes a plurality of battery cells connected in series or in parallel. Based on the bucket effect, the capacity and the service life of the energy storage battery depend on the battery cell with the lowest capacity. Therefore, continuous self-discharge anomaly of the battery cell can cause abnormal electric energy of the energy storage battery. Therefore, it is necessary to identify the abnormal battery cell in the energy storage battery. When the self-discharge anomaly of the battery cell is identified, the abnormal battery cell can be timely repaired or replaced by the battery management system (BMS), so as to ensure the safety and reliability of the whole energy storage battery.
[0033] The related art can estimate the self-discharge rate of the battery cell by the pressure drop method, and take the self-discharge rate as an evaluation index of the self-discharge of the battery cell, and determine whether the battery cell has a self-discharge anomaly according to the self-discharge rate. However, the pressure drop method needs to place the energy storage battery in an experimental environment for a long time, so that the target abnormal battery cell identification method is complex to operate, and the long-time placement also leads to low identification efficiency of the abnormal battery cell. In addition, in the case where the energy storage battery is connected to the power grid, the energy storage battery cannot meet the long-time placement condition according to the scheduling adjustment state of the power grid.
[0034] Therefore, the embodiments of the present application provide an abnormal battery cell identification method and an energy storage system, which can improve the identification efficiency of the abnormal battery cell and simplify the identification steps, and have good versatility.
[0035] Please refer to Figure 1 , Figure 1 is a flowchart of an abnormal battery cell identification method provided by the embodiments of the present application. As shown in the abnormal battery cell identification method shown in Figure 1 , the following steps S110 to S120 are included.
[0036] Step S110, in the case where a first battery cell satisfying a first preset condition exists in the energy storage battery, performing balancing operation on the remaining battery cells except the first battery cell in the energy storage battery; wherein the SOC of the first battery cell is in a first interval, and the SOC of the remaining battery cells is greater than the maximum value of the first interval.
[0037] The SOC (State of Charge) of the battery cell represents the state of charge of the battery cell, which can be understood as the remaining power of the battery cell. When the energy storage battery performs charging and discharging operations, the charging operation is realized by inputting a charging current to the battery cell, and the discharging operation is realized by outputting a discharging current from the battery cell. When the energy storage battery performs charging and discharging operations, the charging and discharging currents have the same effect on the power of each battery cell. That is, when the energy storage battery performs charging operation, the power of each battery cell is the same; when performing discharging operation, the power of each battery cell is also the same. In the case that the initial power of each battery cell is the same, the remaining power of each battery cell after the energy storage battery performs charging and discharging operations should also be the same. If there is a difference in the remaining power between the battery cells of the energy storage battery, the battery cells with power difference may have self-discharge abnormalities. The existence of self-discharge abnormalities in the battery cells may affect the overall power of the energy storage battery, and timely abnormality identification is required.
[0038] The first interval is an interval corresponding to the SOC of the battery cell. The low SOC interval of the battery cell is represented by the first interval according to the embodiments of the present application, which is used to determine the battery cell with abnormal risk. It can be understood that the battery cell in the first interval, which has abnormal risk, is the battery cell with power difference from most battery cells in the energy storage battery and low power.
[0039] After determining the battery cell with abnormal risk according to the first interval, the embodiments of the present application further need to judge the battery cell with abnormal risk according to the first preset condition. The battery cell that meets the first preset condition and has SOC in the first interval is regarded as the first battery cell, and the battery cell in the energy storage battery except the first battery cell is regarded as the remaining battery cell. The first preset condition can limit the number of battery cells with abnormal risk to ensure the accuracy and reliability of abnormal battery cell identification.
[0040] It can be understood that the first battery cell of the embodiments of the present application can include only one battery cell, or can include multiple battery cells. The embodiments of the present application do not limit the number of first battery cells, as long as there is a battery cell that meets the first preset condition and is in the first interval.
[0041] After determining the first battery cell, the embodiments of the present application perform balancing operation on the remaining battery cells in the energy storage battery except the first battery cell. The balancing operation can reduce or eliminate the power difference between the battery cells through power balancing, and ensure the consistency of all battery cells in the energy storage battery. Through the balancing operation on the remaining battery cells, the embodiments of the present application make the state of charge of all battery cells in the energy storage battery the same, so as to realize the identification of abnormal battery cells under the condition that the state of charge of all battery cells in the energy storage battery is the same.
[0042] Exemplarily, since the SOC of the first battery cell is less than the SOC of the remaining battery cells, the equalization operation on the remaining battery cells in the embodiments of the present application can be to reduce the power of the remaining battery cells in an active consumption manner, so as to reduce the SOC of the remaining battery cells to be consistent with the SOC of the first battery cell.
[0043] In step S120, after the equalization operation, if there is a second battery cell in the energy storage battery, and the second battery cell and the first battery cell both include a third battery cell satisfying a second preset condition, the abnormality of the third battery cell is determined according to the equalization amount of the equalization operation; wherein the SOC of the second battery cell is in the first interval.
[0044] Since the abnormal battery cell identification method of the embodiments of the present application does not require the energy storage battery to be in a stationary state, while the equalization operation is performed on the remaining battery cells in step S110, the energy storage battery can still be in a working state, that is, each battery cell in the energy storage battery can continue to perform charging and discharging operations. That is, in the case of equalizing the remaining battery cells to consume the power of the remaining battery cells, since the energy storage battery is still in a working state, the state of charge of the battery cells in the energy storage battery is in a changing state.
[0045] As mentioned above, the battery cell in the first interval indicates that the battery cell is in the low SOC interval, and there is a difference in power with the remaining battery cells and belongs to the low power interval. After the equalization operation is performed on the remaining battery cells in step S110, the battery cells in the energy storage battery are judged again to determine whether there is a second battery cell in the first interval of the low SOC in the energy storage battery. In the case where there is a second battery cell, it indicates that there is still a battery cell with abnormal risk in the energy storage battery at this time.
[0046] It is determined whether the second battery cell and the first battery cell both include a third battery cell satisfying a second preset condition. In the case where the second battery cell and the first battery cell both include a third battery cell satisfying a second preset condition, it indicates that before the equalization operation is performed on the remaining battery cells, the third battery cell with abnormal risk still has abnormal risk after the equalization operation, and the abnormality of the third battery cell can be determined according to the equalization amount of the equalization operation.
[0047] It should be noted that the first battery cell and the second battery cell in the embodiments of the present application can be one battery cell or multiple battery cells. In the case where the first battery cell and the second battery cell each include only one battery cell, the third battery cell is the one battery cell; in the case where the first battery cell and / or the second battery cell include multiple battery cells, the third battery cell is the same battery cell, for example, the first battery cell includes three battery cells, which are No. 1 battery cell, No. 2 battery cell and No. 3 battery cell, and the second battery cell includes two battery cells, which are No. 1 battery cell and No. 4 battery cell, and the third battery cell is No. 1 battery cell included in both.
[0048] Since the abnormal cell of the energy storage battery is identified in the embodiment of the present application, the cells of the energy storage battery are still in the working state, therefore, the SOC of the third cell is judged by the second preset condition, so as to ensure that the identified abnormal cell is the cell with self-discharge abnormality.
[0049] Please refer to Figure 2 , Figure 2 is a schematic diagram of the state of charge of the cell provided by the embodiment of the present application. As shown in Figure 2 , i represents the cell identification in the energy storage battery, and Cell_i represents the i th cell in the energy storage battery. As shown in Figure 2 (a), in the initial state of the energy storage battery in grid-connected operation, the state of charge of each cell in the energy storage battery is basically consistent. As shown in Figure 2 (b), after one month of charging and discharging of the energy storage battery, there may be a difference in the electric quantity between the cells of the energy storage battery. When identifying the abnormal cell, the embodiment of the present application does not define the cell with the difference in the electric quantity as the abnormal cell, but controls all the cells in the energy storage battery to be in the same state through the balancing operation, and after balancing for a period of time, the difference in the electric quantity between the cells in the energy storage battery is obtained to see whether there is still a cell with low electric quantity. If there is still a second cell with low electric quantity in the energy storage battery, and the second cell and the first cell both include a third cell, that is, there is a cell in the low electric quantity interval before and after balancing, it is considered that the cell may have self-discharge abnormality, and the abnormality of the third cell can be determined according to the balancing amount of the balancing operation. As shown in Figure 2 (c), the difference between the cells in the energy storage battery is mainly due to the abnormal self-discharge current of the cells. In the case that the state of the cells in the energy storage battery is consistent through the balancing operation, if there is still a difference in the electric quantity between the cells, it is possible that the cells are abnormal and cause self-discharge abnormality, and the abnormal state of the cells can be determined based on the balancing amount of the balancing operation.
[0050] In the embodiment of the present application, when identifying the abnormal cell of the energy storage battery, the first cell with abnormal risk in the first interval is determined in the energy storage battery, and the balancing operation of the remaining cells other than the first cell is used to control all the cells in the energy storage battery to have the same state of charge, and then the second cell with abnormal risk in the first interval is determined in the energy storage battery after the balancing operation. In the case that the first cell and the second cell both include a third cell, the abnormal state of the third cell is determined according to the balancing amount of the balancing operation of the remaining cells, so as to identify the abnormal cell of the energy storage battery.
[0051] The abnormal battery cell identification method provided in the embodiments of the present application does not need to keep the energy storage battery for a long time, and the energy storage battery can be kept in a working state, and has strong versatility.
[0052] In some embodiments, the abnormality of the third battery cell is determined according to the balancing amount of the balancing operation, including: in a case where the duration of the balancing operation is the second duration, obtaining a first balancing amount of the balancing operation within the second duration; and in a case where the first balancing amount is greater than a preset balancing amount threshold, determining that the third battery cell is abnormal.
[0053] In the embodiments of the present application, the balancing operation on the remaining battery cells can improve the reliability of battery cell abnormality identification by performing the balancing operation for a second duration. The second duration can be a week, a month or even a longer period of time. It can be understood that the balancing operation for the second duration does not necessarily mean that the balancing operation is continuously performed for the second duration. If an abnormality such as excessive temperature occurs during the balancing operation on the remaining battery cells, the balancing operation can be temporarily stopped to ensure the safety and reliability of the energy storage battery.
[0054] Exemplarily, the balancing operation can be performed by connecting the remaining battery cells to the balancing circuit to balance the remaining battery cells through the balancing resistor in the balancing circuit to consume the electric quantity of the remaining battery cells. The balancing circuit controls the start of the balancing operation through the on-off state of the balancing switch. As mentioned before, to ensure the safety and reliability of the energy storage battery, the balancing operation can not be continuously performed, and correspondingly, when the balancing operation is performed on the remaining battery cells through the balancing switch, the on time of the balancing switch is less than or equal to the second duration.
[0055] The preset balancing amount threshold can be determined according to the error data of the balancing operation obtained through experiments. The balancing error data can be 3% or 5%, and the preset balancing amount threshold can be determined according to different balancing error data in different scenarios.
[0056] The first balancing amount represents the electric quantity consumed by the remaining battery cells within the second duration through the balancing operation. In some embodiments, the first balancing amount can be determined according to the balancing current during the balancing operation, the duration of the balancing operation and the rated capacity of the battery cell.
[0057] The balancing amount can be represented as the ratio of the balancing electric quantity consumed or transferred by the balancing operation to the rated capacity of the battery cell. The balancing electric quantity can be determined according to the balancing current during the balancing operation and the duration of the balancing operation. The balancing current can be obtained by collecting the current on the balancing circuit, and the duration of the balancing operation can be obtained by collecting the on time of the balancing switch on the balancing circuit.
[0058] Please continue to refer to Figure 2 , the difference in the amount of electricity between the battery cells is mainly related to the equalization current of the equalization operation and the self-discharge current of the battery cell. In the case where the third battery cell is determined to have an abnormal risk, the abnormal state of the third battery cell is judged by the equalization amount of the equalization operation. For example, in the case where the first equalization amount is greater than the preset equalization amount threshold, it indicates that the self-discharge current of the battery cell causes the difference in the amount of electricity between the battery cells, so that the equalization operation consumes more than the preset equalization amount threshold. It can be determined that the third battery cell is an abnormal battery cell.
[0059] The embodiment of the present application determines the abnormal state of the third battery cell based on the first equalization amount of the second duration equalization operation, without the need for complex calculation models or detection devices. The operation is simple and low in cost, and the abnormal battery cell can be identified during normal operation of the energy storage battery, and the universality is good.
[0060] In some embodiments, the first battery cell satisfying the first preset condition includes: the number of battery cells of the first battery cell is less than or equal to a first threshold, or the ratio of the number of battery cells of the first battery cell to the total number of battery cells of the energy storage battery is less than or equal to a second threshold.
[0061] In the abnormal battery cell identification of the embodiment of the present application, after determining the battery cell in the first interval that has an abnormal risk, the battery cell in the first interval is further judged according to the first preset condition to obtain the first battery cell. The first preset condition can be a condition corresponding to the number of battery cells with an abnormal risk, such as the number of battery cells of the first battery cell, or the proportion of the number of first battery cells in the total number of battery cells of the energy storage battery. It can be understood that the number of first battery cells is less than a certain threshold, or the proportion of the number of first battery cells is less than a certain threshold, which means that the first battery cell is a small part of the entire battery pack. Therefore, the abnormality can be identified by equalizing the other battery cells.
[0062] It can be understood that the abnormal battery cell identification of the embodiment of the present application is to first determine the first battery cell with a difference in the amount of electricity in the energy storage battery, and further determine the reason for the difference in the amount of electricity of the first battery cell based on the equalization operation of the remaining battery cells in the energy storage battery except the first battery cell, to realize the identification of the abnormal battery cell. Therefore, when identifying the abnormality by the embodiment of the present application, the number of first battery cells can be limited by the first preset condition to ensure that there are remaining battery cells for equalization operation in the energy storage battery. In addition, to ensure the accuracy of the abnormality identification of the embodiment of the present application, the proportion of the number of first battery cells can be limited within a certain range.
[0063] Exemplarily, the number of the first battery cell is one. The embodiment of the present application realizes the identification of the abnormal battery cell through the balancing operation of the battery cell. In the case that there is only one first battery cell, the remaining battery cells can also be balanced in electric quantity through the method of the embodiment of the present application, so that all the battery cells in the energy storage battery are in the same state, and then the abnormal state of the first battery cell is determined after balancing for a period of time.
[0064] Compared with the method for determining the abnormal battery cell by calculating the pressure drop in the related art, the embodiment of the present application can also realize the abnormal identification in the case that there is only one abnormal battery cell in the energy storage battery, and has good universality.
[0065] In some embodiments, the third battery cell satisfying the second preset condition includes that the first SOC corresponding to the third battery cell before the balancing operation is greater than the second SOC after the balancing operation.
[0066] In the process of identifying the abnormal battery cell, the embodiment of the present application also sets the second preset condition to limit the SOC of the third battery cell, so as to avoid that the third battery cell has no self-discharge abnormality, but has a low state of charge due to the charging and discharging operation of the energy storage battery or other reasons, and reduce the probability of error in identifying the abnormal battery cell.
[0067] The third battery cell satisfying the second preset condition is that the first SOC before the balancing operation is greater than the second SOC after the balancing operation. It can be understood that the balancing operation on the remaining battery cells in step S110 can control all the battery cells in the energy storage battery to be in the same state (such as the discharging state) through the balancing operation. After balancing for a period of time, if the energy storage battery still includes the third battery cell having a difference in electric quantity from the remaining battery cells, and the third battery cell has a difference in electric quantity from the remaining battery cells before the balancing operation, and the SOC of the third battery cell is lower and lower (i.e. the difference is larger and larger) with the balancing operation on the remaining battery cells, it indicates that the third battery cell has a low electric quantity due to self-discharge. In the case that the third battery cell has a difference in electric quantity from the remaining battery cells, it indicates that the self-discharge quantity of the third battery cell is different from that of the remaining battery cells, and the third battery cell has a self-discharge abnormality, which belongs to the battery cell having the abnormal state.
[0068] In some embodiments, the first interval is in a low SOC linear interval in an open circuit voltage-state of charge curve of the battery cell.
[0069] The open circuit voltage (OCV) is the voltage between the positive electrode and the negative electrode of the battery cell in an open circuit state. The open circuit state can be a state in which the battery cell is connected with a load. Exemplarily, the OCV can be obtained according to the voltage of the battery cell in a static state.
[0070] The open-circuit voltage-state-of-charge curve represents the relationship between the OCV of the battery cell and the SOC. By analyzing the OCV-SOC curve, the change between the open-circuit voltage of the battery cell and the battery cell capacity can be determined, and the change state of the battery cell capacity under different open-circuit voltages of the battery cell can also be determined.
[0071] Please refer to Figure 3 , Figure 3 is a schematic diagram of an open-circuit voltage-state-of-charge curve of a battery cell provided by an embodiment of the present application. The same type of battery cell is usually used in the same energy storage battery, so the same SOC-OCV curve can be referred to when identifying an abnormal battery cell in the present embodiment.
[0072] As shown in the open-circuit voltage-state-of-charge curve, Figure 3 , according to different SOC values, the OCV can be divided into a low linear SOC interval, a plateau interval, and a high linear SOC interval; wherein the low linear SOC interval represents the SOC interval at the end of discharging of the battery cell, and the high linear SOC interval represents the SOC interval at the end of charging of the battery cell. In the low linear SOC interval and the high linear SOC interval, the OCV and the SOC are in a linear relationship, and the corresponding SOC can be obtained by the OCV, that is, the remaining capacity of the battery cell can be determined according to the voltage of the battery cell. In the plateau interval, the remaining capacity of the battery cell cannot be directly determined according to the voltage of the battery cell.
[0073] Taking the open-circuit voltage-state-of-charge curve shown in Figure 3 as an example, when the SOC of the battery cell is in the SOC0-SOC1 interval, the OCV of the corresponding battery cell is in the low linear SOC interval, and the range of the OCV is V0-V1; when the SOC of the battery cell is in the SOC1-SOC2 interval, the OCV of the corresponding battery cell is in the plateau interval, and the range of the OCV is V1-V2; when the SOC of the battery cell is in the SOC2-SOC3 interval, the OCV of the corresponding battery cell is in the high linear SOC interval, and the range of the OCV is V2-V3.
[0074] When identifying an abnormal battery cell, the present embodiment needs to determine the battery cell that has an abnormal risk of identification according to the remaining capacity of the battery cell. When the SOC of the battery cell is in the plateau interval of the open-circuit voltage-state-of-charge curve, the slope of the curve in the plateau interval is low, and the accurate SOC cannot be obtained by the OCV. Therefore, the remaining capacity of the battery cell needs to be determined based on the linear SOC interval. The low linear SOC interval has a wider interval range than the high interval SOC, and the present embodiment determines the interval range of the first interval based on the low linear SOC interval. That is, the SOC interval corresponding to the range of the OCV in V0-V1 in Figure 3 is taken as the first interval.
[0075] In some embodiments, determining the first interval according to the low linear SOC interval at the end of the discharging can be to set a part of the low linear SOC interval as the first interval. For example, the maximum value of the first interval is set to be less than the maximum value of the low linear SOC interval. Still taking the open-circuit voltage- state-of-charge curve shown in the above as an example, the maximum SOC of the low linear SOC interval is denoted as SOC1, and the maximum value of the first interval is less than SOC1, such as setting the first error less than SOC1 as the maximum value of the first interval. The first error can be determined according to the SOC calculation error of the battery cell, for example, 3%. That is, in the case that there is a battery cell with a SOC less than SOC1-3% in the energy storage battery, the battery cell is taken as the first battery cell, and the equalization operation is performed on the remaining battery cells except the first battery cell in the energy storage battery. Figure 3
[0076] The embodiments of the present application determine the first interval according to the low linear SOC interval of the open-circuit voltage- state-of-charge curve of the battery cell, can calibrate the SOC by OCV when performing the equalization operation on the energy storage battery, obtain the accurate SOC of the battery cell, and then can realize the identification of the abnormal battery cell based on the equalization operation on the remaining battery cells.
[0077] In some embodiments, the abnormal battery cell identification method further includes: in the case that the battery current value of the energy storage battery continuously reaches zero for a time length exceeding a first time length, determining the open-circuit voltage value according to the battery cell voltage value of the battery cell in the energy storage battery, to determine the SOC of each battery cell in the energy storage battery in the open-circuit voltage- state-of-charge curve according to the open-circuit voltage value.
[0078] The embodiments of the present application can obtain the accurate state-of-charge of the battery cell according to the open-circuit voltage based on the open-circuit voltage- state-of-charge curve, and determine the remaining capacity of the battery cell. The open-circuit voltage of the battery cell can be obtained by collecting the voltage of the battery cell in the open-circuit state. The open-circuit state is that the battery cell is not connected to a load and is in a stationary state. When the battery cell is in the open-circuit state, the battery current value of the energy storage battery is zero.
[0079] For example, the embodiments of the present application can collect the energy storage current value of the energy storage battery, and in the case that the battery current value of the energy storage battery continuously reaches zero for a first time length, determine that the energy storage battery is in the open-circuit state. The voltage of the battery cell in the open-circuit state is collected, the collected voltage value is taken as the open-circuit voltage value, and the SOC of each battery cell in the energy storage battery is determined based on the low SOC linear interval of the open-circuit voltage- state-of-charge curve.
[0080] In some embodiments, the equalization operation on the remaining battery cells except the first battery cell in the energy storage battery includes: connecting each battery cell in the remaining battery cells to an equalization resistor respectively; and controlling each remaining battery cell to discharge at a preset current, to consume the capacity of each remaining battery cell through the equalization resistor.
[0081] The equalization operation on the remaining battery cells in the embodiment of the application mainly consumes the electric quantity of the remaining battery cells through the equalization operation, and eliminates the electric quantity difference between the first battery cell and the remaining battery cells, so that the electric quantity of the first battery cell is the same as or similar to that of the remaining battery cells.
[0082] Exemplarily, the equalization operation on the remaining battery cells can be performed through passive equalization, each of the remaining battery cells is connected with an equalization resistor, and when the equalization operation on the remaining battery cells is started, the remaining battery cells are controlled to discharge to the equalization resistor at a preset current. When the discharging current flows through the equalization resistor, heat is generated on the equalization resistor, and the consumption of the electric quantity of the first battery cell is realized.
[0083] Please refer to Figure 4 , Figure 4 is a schematic diagram of a battery cell equalization circuit provided by the embodiment of the application. As shown in Figure 4 , the battery cell is connected with an equalization resistor. When the equalization switch is opened, the equalization loop is conducted, and the electric quantity of the battery cell is consumed on the equalization resistor in the form of heat. Taking the equalization of the No. 2 battery cell as an example, the No. 2 battery cell is connected with an equalization resistor, and the equalization resistor includes three parallel resistors. The equalization switch corresponding to the No. 2 battery cell is Q2, and the control end of Q2 is connected with a drive resistor to drive the control switch S2. When it is necessary to discharge the No. 2 battery cell, the control switch S2 is closed, an electric signal is applied to the control of the equalization switch Q2 through the drive resistor to turn on the equalization switch Q2, so that the No. 2 battery cell, the equalization resistor and the equalization switch Q2 form a path, and the electric quantity of the No. 2 battery cell is consumed on the equalization resistor in the form of heat.
[0084] It should be noted that the equalization resistor in the embodiment of the application includes three parallel resistors. In actual application, the number and resistance value of the equalization resistor can be determined according to different connection modes of the resistors, as long as the electric quantity of the battery cell can be consumed through the equalization resistor in the embodiment of the application to ensure that the first battery cell and the remaining battery cells have the same residual electric quantity.
[0085] In some embodiments, the abnormal battery cell identification method further includes: in a case where it is determined that the third battery cell is abnormal, outputting prompt information.
[0086] The prompt information can include the abnormal battery cell identification result of the energy storage battery, such as the identified abnormal battery cell information. The prompt information can display the battery cell identifier of the identified abnormal battery cell through a WEB page, so that the operation and maintenance personnel can determine the specific position of the abnormal battery cell according to the battery cell identifier, and facilitate the operation and maintenance personnel to repair and replace the abnormal battery cell in time.
[0087] The prompt information can also include an operation prompt for the abnormal battery cell, such as an abnormal clearing operation such as repairing or replacing the abnormal battery cell, so that the energy storage battery can recover to normal after the abnormal clearing operation. The repaired battery cell can be a battery cell that is identified as abnormal and is repaired or activated to restore the abnormal battery cell to a normal state. Alternatively, the abnormal battery cell is directly replaced to improve the reliability of the energy storage battery.
[0088] Next, the abnormal battery cell identification method of the embodiment of the present application will be described through a specific example. Please refer to Figure 5 , Figure 5 is a schematic diagram of a battery cell voltage of an energy storage battery provided by the embodiment of the present application. In Figure 5 , the voltage between the battery cells is different, and the battery cells of the energy storage battery need to be identified for abnormalities to determine whether the battery cell with voltage difference is caused by the self-discharge abnormality of the battery cell.
[0089] Please refer to Figure 6 , Figure 6 is a flowchart of another abnormal battery cell identification method provided by the embodiment of the present application. As Figure 6 indicated, in some embodiments, the abnormal battery cell identification method includes the following steps S610 to S690.
[0090] Step S610, collecting a battery cell voltage value of each battery cell in the energy storage battery;
[0091] Step S620, collecting a battery current value of the energy storage battery;
[0092] Step S630, determining whether the battery current value is zero for one hour.
[0093] In the case where the battery current value is zero for one hour, it is determined that the energy storage battery is in an open circuit state at this time, and step S640 is performed. In the case where the battery current value does not satisfy the condition of being zero for one hour, it is considered that the battery has not yet been in an open circuit state at this time, and the identification condition is not satisfied, and the abnormal battery cell identification process is exited.
[0094] Step S640, determining whether there is a first battery cell in the energy storage battery according to the battery cell voltage value.
[0095] In the case where the battery current value is zero for one hour, it is determined that the energy storage battery is in an open circuit state, and the collected battery cell voltage value is taken as an open circuit voltage value of the battery cell. The SOC of the energy storage battery is determined according to the open circuit voltage value and the open circuit voltage-state of charge curve. It is determined whether there is a first battery cell whose SOC satisfies a first preset condition, and the SOC of the first battery cell is in a first interval of a low linear SOC in the open circuit voltage-state of charge curve. The first preset condition is that the number of the first battery cell is less than or equal to a first threshold value.
[0096] In the case that the first battery cell exists in the energy storage battery, the battery cell considered to have an abnormal risk in the energy storage battery is executed step S650.
[0097] In the case that the battery cell in the first interval does not exist in the energy storage battery, the state of charge of the battery cell cannot be determined according to the voltage value of the battery cell, and whether the battery cell has an abnormal risk cannot be further determined, and the abnormal battery cell identification process is exited.
[0098] In the case that the battery cell in the first interval exists in the energy storage battery, but the battery cell in the first interval does not satisfy the first preset condition, for example, all battery cells in the energy storage battery are in the first interval, it is considered that there is no abnormal battery cell in the energy storage battery, or the battery cell marked with an abnormal risk has been cleared, and the abnormal battery cell identification process is also exited.
[0099] Step S650, the remaining battery cells except the first battery cell in the energy storage battery are subjected to equalization operation.
[0100] The equalization operation is performed on the remaining battery cells, and the SOC of the remaining battery cells is adjusted to be the same as that of the first battery cell through the equalization operation, so that the states of all battery cells are consistent.
[0101] Step S660, in the case that the equalization operation lasts for one month, it is judged whether a second battery cell exists in the energy storage battery, and the second battery cell and the first battery cell both include a third battery cell satisfying a second preset condition.
[0102] Step S650 makes the states of all battery cells in the energy storage battery consistent through the equalization operation on the remaining battery cells. After the equalization operation on the remaining battery cells for a period of time, the SOC of the energy storage battery is determined according to the open circuit voltage value and the open circuit voltage-state of charge curve, and it is judged whether a second battery cell exists, and the SOC of the second battery cell is also in the first interval of the low linear SOC in the open circuit voltage-state of charge curve. In the case that the second battery cell exists, it indicates that the energy storage battery still has a battery cell with an abnormal risk.
[0103] In the case that the third battery cell existing in the first battery cell is included in the second battery cell, and the third battery cell satisfies the second preset condition, the abnormal state of the third battery cell needs to be further determined according to the equalization amount of the equalization operation. The third battery cell of the second preset condition indicates that the SOC of the third battery cell after the equalization operation is less than the SOC before the equalization operation. The first battery cell and the second battery cell include the same risk battery cell, which indicates that the abnormal risk of the risk battery cell has not been eliminated after the equalization operation. At this time, if the SOC of the risk battery cell becomes lower with the equalization operation for one month, it indicates that the risk battery cell includes the SOC reduction caused by self-discharge abnormality, and the risk battery cell is further identified as the third battery cell in step S670.
[0104] Step S670, the equalization amount of the equalization operation is compared with a preset equalization threshold.
[0105] In a case where the equalization amount of the equalization operation is greater than the preset equalization threshold, it is determined that the third battery cell is abnormal, and step S680 is performed. In a case where the equalization amount of the equalization operation is less than or equal to the equalization threshold, it is considered that the third battery cell does not have a self-discharge abnormality, and the current abnormal battery cell identification process is exited.
[0106] Step S680, prompting the abnormal third battery cell on the WEB interface.
[0107] The embodiments of the present application do not need a complex calculation model or detection device, and the abnormal battery cell identification can be realized through the equalization operation on part of the battery cells in the energy storage battery. The calculation is simple, the identification cost is low, and the identification efficiency is high. The abnormal battery cell identification method of the embodiments of the present application does not need to be placed for a long time, and the energy storage battery can remain in a working state, and has strong versatility.
[0108] According to a second aspect of the present application, in some embodiments, an energy storage system is provided. Please refer to Figure 7 , Figure 7 is a structural schematic diagram of an energy storage system provided by the embodiments of the present application, as Figure 7 shown, the energy storage system includes an energy storage battery module 100 and a control module 200, the energy storage battery module 100 includes a battery cell 110, the control module 200 is connected with the energy storage battery module 100, and is used for executing the abnormal battery cell identification method in the above-mentioned embodiments on the battery cell in the energy storage battery module 100.
[0109] The energy storage battery module 100 is a module for storing electric energy in the energy storage system, the energy storage battery module 100 includes at least one battery cell, the battery cell 110 in the energy storage battery module 100 can be connected in series or in parallel, and the connection mode of the battery cell 110 in the energy storage battery module 100 is not limited in the present application. The control module 200 is used for identifying the abnormality of the battery cell 110 in the energy storage battery module 100, so as to improve the reliability of the energy storage system.
[0110] In some embodiments, the control module 200 includes a collection circuit connected with the energy storage battery module 100 and / or the battery cell 110, and an equalization circuit connected with the battery cell 110. The collection circuit is used for collecting the electrical parameters of the energy storage battery module 100 and / or the battery cell 110. The equalization circuit is used for performing equalization operation on the battery cell 110.
[0111] The electrical parameters can include current parameters and / or voltage parameters. The collection circuit can be directly connected with the energy storage battery module 100 to collect the battery current value and / or the battery voltage value of the energy storage battery module 100; or can be directly connected with the battery cell 110 to collect the battery cell current value and / or the battery cell voltage value of the battery cell 110.
[0112] The abnormal battery cell identification method provided in the embodiments of the present application needs to firstly determine that the energy storage battery module 100 is in an open circuit state according to the collected battery current value, and then determine the SOC of the battery cell according to the open circuit voltage-charge state curve and the voltage value of the battery cell in the open circuit state.
[0113] Please refer to Figure 8 and Figure 9 , Figure 8 is a circuit diagram of a voltage acquisition circuit provided by the embodiments of the present application, Figure 9 is a control circuit diagram of an analog front end chip (AFE) provided by the embodiments of the present application. As shown in Figure 8 , the voltage acquisition circuit includes a plurality of parallel voltage acquisition paths, each of which includes an acquisition resistor, a clamping diode and a capacitor. Taking the voltage acquisition path of the No. 1 battery cell as an example, the No. 1 battery cell is connected to the port C5_1 of the AFE through the acquisition resistor R1, and the voltage value of the battery cell is acquired through the acquisition resistor R1 under the control of the AFE. The acquisition path between the No. 1 battery cell and the No. 2 battery cell is provided with a diode for realizing circuit protection through voltage clamping.
[0114] Please refer to Figure 10 , Figure 10 is a circuit diagram of a current acquisition circuit provided by the embodiments of the present application. One end of the current acquisition circuit is connected to the output end of the energy storage battery module 100 through a connection terminal, and the other end is connected to a sampling chip. The battery acquisition circuit acquires the current parameter of the energy storage battery module 100, and takes the acquired current parameter as the battery current value of the energy storage battery module 100.
[0115] Please continue to refer to Figure 4 , the circuit diagram of the equalization circuit. The equalization circuit includes an equalization resistor, an equalization switch Q and a control switch S. One end of the equalization resistor is connected to the battery cell, and the other end is connected to the equalization switch Q. The equalization switch Q is turned on or turned off under the control of the control switch S. The control switch S is connected to the AFE. When it is needed to perform equalization operation on the battery cell, the AFE controls to close the control switch S corresponding to the battery cell, so that the control signal applied to the equalization switch Q is turned on after the control switch is closed, and the battery cell and the equalization resistor form a loop. After the equalization loop is formed, the battery cell discharges according to a preset current, so that the equalization current flows through the equalization resistor, and the equalization resistor consumes the electric quantity of the battery cell in the form of heat. When it is not needed to perform equalization operation on the battery cell, the AFE controls to open the control switch S corresponding to the battery cell, so that the control signal applied to the equalization switch Q is turned off after the control switch is opened, and the loop of the battery cell and the equalization resistor is disconnected, and the equalization operation is stopped.
[0116] In some embodiments, the energy storage system further comprises an interaction module. The interaction module is connected with the control module 200, and is configured to perform a prompt operation when the control module 200 determines that the third battery cell is abnormal.
[0117] Exemplarily, the interaction module can be a display device, to remind an operation and maintenance personnel of the position of the third battery cell through a WEB display page or the like when it is determined that the third battery cell is abnormal, so as to facilitate the operation and maintenance personnel to repair the abnormal battery cell in time, and ensure the safety and reliability of the energy storage system.
[0118] It should be understood that the above embodiments corresponding to the energy storage system are described in detail for the structure and working mode of each module in the energy storage system and the beneficial effects thereof, please refer to the above embodiments of the abnormal battery cell identification method, and no more description is given here.
[0119] In the description of the present application, the terms "first", "second" are only for descriptive purpose, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise specifically limited.
[0120] In the above embodiments, the description of each embodiment is focused on, and the parts not described in detail in a certain embodiment can be referred to the relevant description of other embodiments.
[0121] The embodiments, implementation manners and related technical features of the present application can be combined, replaced with each other without conflict.
[0122] The above is only the preferred embodiments of the present application, and does not limit the present application in any form, but any simple modification, equivalent change and modification made according to the technical essence of the present application without departing from the technical scheme of the present application, still belongs to the scope of the technical scheme of the present application.
Claims
1. A method for identifying abnormal battery cells, characterized in that, include: If a first cell in the energy storage battery meets a first preset condition, an equalization operation is performed on the remaining cells in the energy storage battery other than the first cell; wherein the SOC of the first cell is in a first range, and the SOC of the remaining cells is greater than the maximum value of the first range; After the balancing operation, if there is a second cell in the energy storage battery, and both the second cell and the first cell include a third cell that meets the second preset condition, then the abnormal condition of the third cell is determined according to the balancing amount of the balancing operation; wherein the SOC of the second cell is in the first range.
2. The method according to claim 1, wherein the first battery cell satisfying the first preset condition comprises: The number of cells in the first battery cell is less than or equal to a first threshold, or the ratio of the number of cells in the first battery cell to the total number of cells in the energy storage battery is less than or equal to a second threshold.
3. The method according to claim 1, characterized in that, The third battery cell that meets the second preset condition includes: The first SOC of the third cell before the equalization operation is greater than the second SOC of the third cell after the equalization operation.
4. The method according to claim 1, characterized in that, The first interval is located in the low SOC linear interval of the cell's open-circuit voltage-state-of-charge curve.
5. The method according to claim 4, characterized in that, The method further includes: If the battery current value of the energy storage battery remains zero for a period of time exceeding a first duration, the open circuit voltage value is determined based on the cell voltage value of the cells in the energy storage battery, and the SOC of each cell in the energy storage battery is determined based on the open circuit voltage-state of charge curve according to the open circuit voltage value.
6. The method according to any one of claims 1 to 5, characterized in that, The balancing operation for the remaining cells in the energy storage battery, excluding the first cell, includes: Connect each of the remaining battery cells to an equalization resistor; Each of the remaining cells is controlled to discharge at a preset current, so as to consume the power of each of the remaining cells through the equalization resistor.
7. The method according to any one of claims 1 to 5, characterized in that, The step of determining the abnormal condition of the third cell based on the balancing amount of the balancing operation includes: If the duration of the balancing operation is a second duration, obtain the first balancing amount of the balancing operation within the second duration; If the first equalization value is greater than the preset equalization value threshold, the third cell is determined to be abnormal.
8. The method according to any one of claims 1 to 5, characterized in that, The method further includes: If the third battery cell is found to be faulty, a prompt message will be output.
9. An energy storage system, characterized in that, include: An energy storage battery module (100) includes battery cells (110); A control module (200) is connected to the energy storage battery module (100), and the control module (200) is used to perform the abnormal cell identification method as described in any one of claims 1 to 8 on the cells (110) of the energy storage battery module (100).
10. The energy storage system according to claim 9, characterized in that, The control module (200) includes: a data acquisition circuit connected to the energy storage battery module (100) and / or the battery cell (110), and an equalization circuit connected to the battery cell (110); wherein, The acquisition circuit is used to: acquire the electrical parameters of the energy storage battery module (100) and / or the battery cell (110); The equalization circuit is used to perform equalization operations on the battery cell (110).