Capacity calibration method and related device

Abstract

The invention provides a capacity calibration method and a related device, and relates to the field of energy storage systems. Under the condition that the battery cluster meets the capacity calibration condition, the target charge state of the battery cluster is obtained, the battery cluster is charged, and under the condition that the charge state of the battery cluster reaches a discharge depth set value or the running state of the battery cluster is changed, the target charge state of the battery cluster is obtained. The calibration capacity of the battery cluster in the current calibration period is obtained based on the charging amount of the battery cluster, and the capacity calibration value of the battery cluster is determined based on the comparison result of the calibration capacity in the current calibration period and the current capacity value of the battery cluster. Therefore, when the charge state of the battery cluster reaches the discharge depth set value or the operation state of the battery cluster changes, the capacity calibration operation of the battery cluster can be carried out, so that the problem that the battery cluster cannot be fully charged and discharged due to the limit of the discharge depth is avoided; therefore, the problem that the capacity of the battery cluster cannot be calibrated when the battery is fully charged and discharged is solved.

Description

Technical Field

[0001] This application relates to the field of energy storage systems, and more specifically, to a capacity calibration method and related devices. Background Art

[0002] An energy storage system is provided with a battery cluster, the battery cluster includes a plurality of battery packs, and a plurality of battery cells are arranged in the battery packs. If there is an abnormal battery cell in the battery cluster, the abnormal battery cell will affect the capacity of the battery cluster, and it is necessary to replace the abnormal battery cell or the abnormal battery pack where the abnormal battery cell is located.

[0003] After replacing the abnormal battery cell or the abnormal battery pack, the capacity of the battery cluster changes, and it is necessary to perform a capacity calibration operation on the battery cluster. How to accurately calibrate the capacity of the battery cluster is a technical problem that needs to be solved urgently by those skilled in the art. Summary of the Invention

[0004] In view of this, this application provides a capacity calibration method and related devices to achieve the purpose of improving the accuracy of capacity calibration of the battery cluster.

[0005] To solve the above technical problems, this application adopts the following technical solutions:

[0006] The first aspect of this application discloses a capacity calibration method, including:

[0007] When the battery cluster meets the capacity calibration condition, obtain the target state of charge of the battery cluster;

[0008] Perform a charging operation on the battery cluster. When the state of charge of the battery cluster reaches the set value of the depth of discharge or the operating state of the battery cluster changes, obtain the calibration capacity of the battery cluster in the current calibration period based on the charging amount of the battery cluster;

[0009] Determine the capacity calibration value of the battery cluster based on the comparison result between the calibration capacity in the current calibration period and the current capacity value of the battery cluster.

[0010] Optionally, the step of obtaining the target state of charge of the battery cluster when the battery cluster meets the capacity calibration condition includes:

[0011] When the state of charge of the battery cells in the battery cluster is in the linear region and the static time of the battery cells reaches the specified time, determine that the battery cluster meets the capacity calibration condition;

[0012] Obtain the state of charge of each battery cell in the battery cluster;

[0013] Take the minimum state of charge as the target state of charge of the battery cluster.

[0014] Optionally, obtaining the state of charge of each battery cell in the battery cluster includes:

[0015] Obtaining the open-circuit voltage of each battery cell in the battery cluster;

[0016] Determining the state of charge corresponding to the open-circuit voltage of the battery cell according to the correspondence between the open-circuit voltage and the state of charge.

[0017] Optionally, obtaining the calibration capacity of the battery cluster in the current calibration period based on the charge amount of the battery cluster includes:

[0018] Obtaining the charge amount of the battery cluster;

[0019] Determining the difference between a preset value and the target state of charge;

[0020] Taking the ratio of the charge amount to the difference as the calibration capacity of the battery cluster in the current calibration period.

[0021] Optionally, determining the capacity calibration value of the battery cluster based on the comparison result between the calibration capacity in the current calibration period and the current capacity value of the battery cluster includes:

[0022] Obtaining the current capacity value of the battery cluster; wherein, when the current calibration period is the first calibration period, the current capacity value is the rated capacity of the battery cluster;

[0023] When the calibration capacity in the current calibration period is greater than or equal to the current capacity value, taking the calibration capacity in the current calibration period as the capacity calibration value of the battery cluster.

[0024] Optionally, when the calibration capacity in the current calibration period is less than the current capacity value, it further includes:

[0025] Taking the current capacity value as the capacity calibration value of the battery cluster.

[0026] Optionally, the state of charge of the battery cluster reaching the set discharge depth includes:

[0027] The state of charge of at least one battery cell in the battery cluster reaches the set maximum discharge depth;

[0028] The change in the operating state of the battery cluster includes: the battery cluster switches from the charging state to the discharging state.

[0029] A second aspect of the present application discloses a capacity calibration device, including:

[0030] An acquisition module, configured to acquire the target state of charge of the battery cluster when the battery cluster meets the capacity calibration condition;

[0031] A determination module, configured to perform a charging operation on the battery cluster, and based on the charging amount of the battery cluster, obtain a calibration capacity of the battery cluster in a current calibration period when the state of charge of the battery cluster reaches a set value of discharge depth or the operating state of the battery cluster changes;

[0032] A calibration module, configured to determine a capacity calibration value of the battery cluster based on a comparison result between the calibration capacity in the current calibration period and the current capacity value of the battery cluster.

[0033] A third aspect of the present application discloses a capacity calibration device, including at least one processor and a memory connected to the processor, wherein:

[0034] The memory is used to store a computer program;

[0035] The processor is configured to execute the computer program so that the electronic device can implement the above-mentioned capacity calibration method.

[0036] A fourth aspect of the present application discloses an energy storage system, including a battery cluster and the above-mentioned capacity calibration device.

[0037] A fifth aspect of the present application discloses a computer program product, including computer-readable instructions, which, when running on an electronic device, enable the electronic device to implement the above-mentioned capacity calibration method provided by the embodiments of the present application.

[0038] The present application provides a capacity calibration method and related devices. In the present application, when the battery cluster meets the capacity calibration condition, the target state of charge of the battery cluster is obtained, a charging operation is performed on the battery cluster, and when the state of charge of the battery cluster reaches the set value of discharge depth or the operating state of the battery cluster changes, the calibration capacity of the battery cluster in the current calibration period is obtained based on the charging amount of the battery cluster, and the capacity calibration value of the battery cluster is determined based on the comparison result between the calibration capacity in the current calibration period and the current capacity value of the battery cluster. That is, the present application can perform a capacity calibration operation on the battery cluster when the state of charge of the battery cluster reaches the set value of discharge depth or the operating state of the battery cluster changes, avoiding the problem that the battery cluster cannot be fully charged and discharged due to the discharge depth limitation, and thus the battery cluster capacity calibration cannot be achieved during full charge and discharge. Description of the Drawings

[0039] To more clearly illustrate the technical solutions in the embodiments of the present application or the related art, the following will briefly introduce the accompanying drawings required for the description of the embodiments or the related art. Obviously, the accompanying drawings in the following description are only the embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can also be obtained based on the provided drawings.

[0040] Figure 1 It is a schematic structural diagram of an energy storage system provided by an embodiment of the present application;

[0041] Figure 2 It is a flowchart of a capacity calibration method provided by an embodiment of the present application;

[0042] Figure 3 It is a schematic diagram of an open circuit voltage - SOC curve provided by an embodiment of the present application;

[0043] Figure 4 It is a flowchart of a capacity calibration process provided by an embodiment of the present application;

[0044] Figure 5 It is another flowchart of a capacity calibration process provided by an embodiment of the present application;

[0045] Figure 6 It is a flowchart of a capacity calibration device provided by an embodiment of the present application. Detailed implementation manners

[0046] The following will clearly and completely describe the technical solutions in the embodiments of the present application in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments of the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present application.

[0047] The structure of the energy storage system is as Figure 1 shown. An SMU (System Management Unit, battery stack management unit) is provided in the energy storage system, and the SMU is connected to multiple BCMUs (Battery Cluster Management Unit, battery cluster management units) to achieve the control of the BCMUs.

[0048] Among them, each BCMU can communicate with each other, and the BCMU is used to realize the control of the battery cluster. A BCMU is connected to a battery cluster RACK, and a plurality of battery packs PACK are arranged in the RACK. The plurality of PACKs can be connected in series. Each PACK is provided with a BMU (Battery Management Unit, battery pack management unit) and a plurality of battery cells. In practical applications, the SMU issues control instructions to the BCMU, and the BCMU issues control instructions to the BMU to realize battery management, such as performing charge and discharge operations on the battery cells.

[0049] During the operation of the energy storage system, for a certain battery cluster, if there are battery cells with abnormal internal resistance or abnormal self-discharge in the battery cluster, the capacity of the PACK with abnormal battery cells will be lower than the average capacity of all PACKs in the battery cluster. Due to the cask effect (under the same RACK, when any one PACK is full, the entire RACK stops charging, and when any one PACK is emptied, the entire RACK stops discharging), the discharge capacity of the RACK in the energy storage system is reduced, and then the discharge capacity of the energy storage system is reduced. In addition, there are also safety risks when the PACK with abnormal battery cells continues to charge and discharge. Therefore, it is necessary to replace the abnormal battery cell or the abnormal PACK where the abnormal battery cell is located.

[0050] After replacing the abnormal battery cell or abnormal PACK, the capacity of the battery cluster has changed, and it is necessary to perform a calibration operation on the capacity of the battery cluster. Currently, when calibrating the capacity of the battery cluster, generally the energy storage system is charged from the full discharge state to the full charge state, and then the capacity calibration operation of the battery cluster is performed. Among them, in one implementation, the voltage of the battery cell in the full discharge state is generally 2.7V, and the voltage of the battery cell in the full charge state is generally 3.65V.

[0051] However, in practical applications, the DOD (Depth of Discharge) upper and lower limits of the operation of the energy storage system are usually set during the operation of the energy storage system, and generally do not allow users to modify them. Among them, DOD is used to measure the percentage between the discharge amount of the battery cell and the rated capacity of the battery cell. When the SOC (State-of-Charge) of the battery cell is greater than the DOD upper limit, the energy storage system stops charging. When the SOC of the battery cell is less than the DOD lower limit, the energy storage system stops discharging.

[0052] Generally, the DOD upper limit refers to the upper SOC limit value that the battery cell is allowed to reach during discharge, and the DOD lower limit refers to the lower SOC limit value that the battery is allowed to reach during discharge. Users can set the DOD upper and lower limits to any value from 0% to 100%, but the DOD upper limit should be higher than the DOD lower limit. In one embodiment, the DOD lower limit is usually not set to 0% to reserve a certain amount of power to prevent the battery from running out of power due to long-term static placement. The DOD upper limit is usually not set to 100% to avoid fully charging the battery, so as to extend the service life of the battery. In one embodiment, the DOD upper limit can be set to a certain value between 95% and 97%. The DOD lower limit can be set to a certain value between 2% and 10%. Due to the setting of the DOD upper and lower limits, the battery cell cannot be fully discharged or fully charged, and the energy storage system cannot be fully discharged or fully charged, so the operation of charging the energy storage system from the fully discharged state to the fully charged state cannot be performed, making it difficult to accurately calibrate the battery cluster capacity.

[0053] Therefore, in the embodiments of the present application, when the battery cluster meets the capacity calibration conditions, the target state of charge of the battery cluster is obtained, and the battery cluster is charged. When the state of charge of the battery cluster reaches the set value of the depth of discharge or the operating state of the battery cluster changes, the calibration capacity of the battery cluster in the current calibration period is obtained based on the charging amount of the battery cluster. Based on the comparison result between the calibration capacity of the current calibration period and the current capacity value of the battery cluster, the capacity calibration value of the battery cluster is determined. That is, the present application can perform the capacity calibration operation of the battery cluster when the state of charge of the battery cluster reaches the set value of the depth of discharge or the operating state of the battery cluster changes, avoiding the problem that the battery cluster cannot be fully charged and discharged due to the depth of discharge limitation, and thus the capacity calibration of the battery cluster cannot be realized during full charge and discharge.

[0054] An embodiment of the present application provides a capacity calibration method. The execution subject of this capacity calibration method can be the BCMU, that is, the capacity calibration operation of the connected RACK is realized through the BCMU. Referring to Figure 2 , a capacity calibration method may include:

[0055] S11. When the battery cluster meets the capacity calibration conditions, obtain the target state of charge of the battery cluster.

[0056] In this embodiment, when capacity calibration is required, step S11 is executed. Among them, the scenarios where capacity calibration is required can be:

[0057] 1. An abnormal battery cell is replaced in the RACK connected to the BCMU, or an abnormal PACK where the abnormal battery cell is located is replaced.

[0058] In practical applications, after replacing the abnormal battery cell or the abnormal PACK where the abnormal battery cell is located in the RACK, the capacity of the RACK changes. At this time, a capacity calibration operation needs to be performed.

[0059] 2. Reach the set capacity calibration time.

[0060] In practical applications, a capacity calibration period can be set to periodically perform the capacity calibration operation of the RACK to ensure the accuracy of the RACK capacity. Therefore, when the periodic capacity calibration time is reached, the capacity calibration operation can be performed.

[0061] 3. Receive a manual or automatic capacity calibration instruction.

[0062] Specifically, when manually or automatically analyzing the operating state of the energy storage system, if it is found that the RACK capacity is inaccurate, a capacity calibration instruction can be issued at this time to perform the capacity calibration operation.

[0063] It should be noted that the capacity calibration in this embodiment can be to perform the capacity calibration operation only on the RACK that has replaced the abnormal battery cell or the abnormal PACK, or to perform the capacity calibration operation on multiple RACKs in the energy storage system, or to perform the capacity calibration operation on all RACKs in the energy storage system.

[0064] After determining that the capacity calibration is required through the above steps, first determine whether the RACK meets the capacity calibration conditions. If it meets, the capacity calibration operation will be performed. If it does not meet, the capacity calibration operation will not be performed. Among them, the capacity calibration conditions can be configured according to the actual situation.

[0065] When the battery cluster meets the capacity calibration conditions, the capacity calibration operation is performed. When performing the capacity calibration operation, the target state of charge of the battery cluster needs to be obtained. The target state of charge in this embodiment is the state of charge of at least one battery cell selected from the battery cluster. The battery cells selected in this embodiment can be configured according to the actual situation, such as the battery cell with the minimum SOC, or the battery cell with a relatively small SOC.

[0066] In one implementation, when the battery cluster meets the capacity calibration conditions, obtaining the target state of charge of the battery cluster may include the following steps:

[0067] When the state of charge of the battery cells in the battery cluster is in the linear region and the static duration of the battery cells reaches the specified time, it is determined that the battery cluster meets the capacity calibration conditions, and then the state of charge of each battery cell in the battery cluster is obtained to use the minimum state of charge as the target state of charge of the battery cluster.

[0068] Among them, this linear region may refer to the linear region at the end of discharge.

[0069] In specific implementation, when performing capacity calibration, the battery cells in the battery cluster are charged from a low SOC state to a high SOC state, and subsequent capacity calibration can be performed based on the charging situation.

[0070] When the SOC of the battery cells in the battery cluster is in the linear region at the end of discharge, the SOC is generally considered to be in the low SOC state. The linear region at the end of discharge can refer to the line segment in the square box in Figure 3 . Among them, Figure 3 is the open-circuit voltage - SOC curve, Figure 3 the abscissa of which is SOC and the ordinate is the open-circuit voltage. In this linear region, the SOC of the battery cell is proportional to the open-circuit voltage. The SOC of the battery cell can be determined by using the open-circuit voltage of the battery cell, and then it can be determined whether the SOC of the battery cell is in the linear region. In one example, when the SOC of the battery cell is between 0% and 15%, the SOC is considered to be in the linear region. In another example, when the SOC of the battery cell is between 0% and 30%, the SOC is considered to be in the linear region. The specific SOC limit value of the linear region is related to the type of the battery cell.

[0071] In addition to the need to satisfy that the state of charge of the battery cells in the battery cluster is in the linear region, it is also necessary to satisfy the condition that the static time of the battery cells reaches the specified time before the battery cluster is considered to meet the capacity calibration condition.

[0072] The condition of limiting the static time of the battery cells to reach the specified time is due to:

[0073] In the actual scenario, during the charge and discharge process of the battery cells, the electrode potential will deviate from its equilibrium potential, that is, the polarization phenomenon occurs. To avoid the problem of inaccurate SOC value inside the battery cell caused by the polarization phenomenon, after the energy storage system stops the charge and discharge operation, the battery cells are left static for at least the specified time (the specific time length can be configured according to the actual situation), waiting for the depolarization of the battery cells (depolarization refers to the process of reducing or eliminating the polarization effect by a certain method to make the electrode potential return to the equilibrium potential). When the voltage reaches the depolarization voltage, the voltage of the battery cell returns to the equilibrium potential, and the SOC of the battery cell can be accurately calculated.

[0074] Therefore, in this embodiment, when the state of charge of the battery cells in the battery cluster is in the linear region and the static time of the battery cells reaches the specified time, the state of charge of the battery cells can be accurately determined, avoiding the problem of inaccurate capacity calibration caused by the inability to accurately determine the state of charge of the battery cells. At this time, it is determined that the battery cluster meets the capacity calibration condition. Since the battery cells in the battery cluster need to be charged from a low SOC state to a high SOC state during capacity calibration, in the embodiments of the present application, it is necessary to determine the SOC of the battery cluster at the start of charging. Generally, since the SOCs of the individual batteries in the battery cluster are all relatively low, the lowest SOC can represent the minimum SOC of the battery cluster. Therefore, the SOCs of the individual battery cells in the battery cluster can be obtained, and the lowest SOC can be used as the target state of charge of the battery cluster. In addition, the average value of multiple relatively low SOCs (such as less than the set SOC value) can also be calculated, and this average value can be used as the target state of charge of the battery cluster.

[0075] In one implementation, when obtaining the state of charge of each battery cell in the battery cluster, the open-circuit voltage of each battery cell in the battery cluster can be obtained first, and then, according to the correspondence between the open-circuit voltage and the state of charge, the state of charge corresponding to the open-circuit voltage of the battery cell can be determined.

[0076] Among them, the correspondence between the open-circuit voltage and the state of charge can be Figure 3 the open-circuit voltage - SOC curve in.

[0077] Specifically, the SOC of the battery cells in the battery cluster is in the linear region. In this linear region, the open-circuit voltage of the battery cells is proportional to the SOC. At this time, the open-circuit voltage of the battery cells can be collected by devices such as voltage sensors, and then, using the proportional relationship between the open-circuit voltage and the SOC, the accurate SOC value can be obtained by looking up a table or calculation. Subsequently, the lowest SOC is used as the target state of charge of the battery cluster to determine the minimum SOC of the battery cluster, which is used as the lowest SOC value for subsequent capacity calibration to obtain the minimum SOC value during battery cluster capacity calibration.

[0078] It should be noted that if the state of charge of the battery cells in the battery cluster is not in the linear region or the static time of the battery cells does not reach the specified time, the capacity calibration operation is not performed first until the state of charge of the battery cells in the battery cluster is in the linear region and the static time of the battery cells reaches the specified time, and then the capacity calibration operation is performed.

[0079] S12. Perform a charging operation on the battery cluster. When the state of charge of the battery cluster reaches the set discharge depth value or the operating state of the battery cluster changes, obtain the calibration capacity of the battery cluster in the current calibration cycle based on the charging amount of the battery cluster.

[0080] In this embodiment, after the minimum SOC of the battery cluster is known, the battery cluster can be charged. After the battery cluster starts charging, the charging amount of the battery cluster can be obtained. In one implementation, the charging current of the battery cluster can be integrated to obtain the charging amount of the battery cluster.

[0081] Specifically, the integration operation can adopt the ampere-hour integration method, that is, during the charging process of the battery cluster, the charging current of the battery cluster is integrated using the ampere-hour integration method to obtain the charging amount chg_cap of the battery cluster.

[0082] During the charging process of the battery cluster, the value of the charging amount chg_cap is continuously updated until the battery cluster stops charging operation, and the final charging amount chg_cap is obtained.

[0083] In this embodiment, there are two scenarios for the battery cluster to stop charging operation. One scenario is that the SOC of the battery cluster reaches the set value of the depth of discharge. In one implementation, the set value of the depth of discharge is the maximum set value of the depth of discharge, that is, the above-mentioned DOD upper limit. When the state of charge of at least one battery cell in the battery cluster reaches the maximum set value of the depth of discharge, it is considered that the SOC of the battery cells in the battery cluster reaches the DOD upper limit. At this time, the battery cluster will stop charging operation. For example, if the DOD upper limit is 95% and the SOC of a certain battery cell in the battery cluster is 95%, it is considered that the SOC reaches the DOD upper limit, and at this time, the battery cluster will stop charging operation.

[0084] Another scenario is to determine that the battery cluster stops charging operation when the operating state of the battery cluster changes. Specifically, since the battery cluster is in a charging state during capacity calibration and the battery cluster needs to be controlled to discharge when energy storage is required, at this time, the battery cluster switches from the charging state to the discharging state, and the operating state of the battery cluster changes. For example, when the battery cluster is charging and the SOC of a certain battery cell increases from 5% to 60%, and at this time the battery cluster needs to discharge, then the battery cluster switches to the discharging state, and it can be determined that the battery cluster stops charging operation.

[0085] In addition, other limiting conditions for the battery cluster to stop charging operation can also be set, such as manual control to stop charging the battery cluster, and the battery cluster needs to stop charging operation due to energy storage system failure, etc. The specific limiting conditions can be configured according to the actual situation and are not limited in this embodiment.

[0086] After the battery cluster stops charging operation, the calibration capacity of the battery cluster in the current calibration period is calculated using the charging operation of this time, that is, the charging amount chg_cap of the current calibration period.

[0087] S13. Determine the capacity calibration value of the battery cluster based on the comparison result between the calibration capacity of the current calibration period and the current capacity value of the battery cluster.

[0088] Among them, the current capacity value of the battery cluster refers to the capacity value of the battery cluster currently in use. This current capacity value can be the rated capacity, a certain capacity calibration value of a historical capacity calibration operation, or the capacity calibration value of the previous calibration cycle. The specific content depends on the actual configuration.

[0089] In this embodiment, when the battery cluster stops the charging operation, since the battery cells in the battery cluster do not reach the fully charged state due to the DOD upper limit, the actually calculated calibration capacity may have inaccurate problems. Therefore, the current capacity value of the battery cluster can be obtained, and the calibration capacity of the current calibration cycle can be calibrated by using the current capacity value of the battery cluster, so as to obtain the capacity calibration value of the battery cluster in the current calibration cycle.

[0090] In this embodiment, when the battery cluster meets the capacity calibration condition, the target state of charge of the battery cluster is obtained, and the battery cluster is charged. When the state of charge of the battery cluster reaches the set value of the depth of discharge or the operating state of the battery cluster changes, the calibration capacity of the battery cluster in the current calibration cycle is obtained based on the charge amount of the battery cluster, and the capacity calibration value of the battery cluster is determined based on the comparison result between the calibration capacity of the current calibration cycle and the current capacity value of the battery cluster. That is, in this application, when the state of charge of the battery cluster reaches the set value of the depth of discharge or the operating state of the battery cluster changes, the capacity calibration operation of the battery cluster can be performed, avoiding the problem that the battery cluster cannot be fully charged and discharged due to the depth of discharge limit, and thus the problem that the battery cluster capacity calibration can only be performed when fully charged and discharged cannot be realized.

[0091] On the basis of any of the above embodiments, referring to Figure 4 , obtaining the calibration capacity of the battery cluster in the current calibration cycle based on the charge amount of the battery cluster may include:

[0092] S21. Obtain the charge amount of the battery cluster.

[0093] In this embodiment, the charge amount of the battery cluster can be obtained by integrating the charging current of the battery cluster. For the specific implementation, refer to the corresponding description above.

[0094] S22. Determine the difference between the preset value and the target state of charge.

[0095] Among them, the preset value is 100%.

[0096] In this embodiment, due to the DOD upper limit, the battery cluster usually cannot perform a full charge operation, so the battery cluster capacity calibration operation cannot be performed during full charge. In this embodiment, the calibration operation will be performed before full charge, that is, when the SOC reaches the DOD upper limit or when a discharge operation is performed before reaching the DOD upper limit.

[0097] During the calibration operation, generally, the difference between the maximum SOC of the battery cells in the battery cluster at the end of charging and the minimum SOC of the battery cells in the battery cluster at the start of charging is calculated to obtain the SOC change amount of the battery cluster during the entire charging process.

[0098] Since the SOC of the battery cluster continuously increases during charging, as Figure 3 shown, after the SOC increases, the SOC of the subsequent battery cluster is no longer in the linear region but in the non-linear region. At this time, the SOC is no longer proportional to the open-circuit voltage, and an accurate SOC value cannot be obtained by calculating the open-circuit voltage. Therefore, at this time, 100% can be used to replace the actual maximum SOC value of the battery cells in the battery cluster. If the battery cluster continues to charge and reaches the linear region at the end of charging, since the interval of this linear region is relatively narrow, it may be impossible to obtain the SOC value or the obtained SOC error is relatively large. At this time, 100% can be used to replace the actual maximum SOC value of the battery cells in the battery cluster.

[0099] In summary, determining the difference between the preset value and the state of charge is the result of calculating "100% - state of charge". Since the state of charge is the minimum SOC of the battery cluster, that is, the result of calculating "100% - minimum SOC".

[0100] S23. Use the ratio of the charging amount to the difference as the calibration capacity of the battery cluster in the current calibration cycle.

[0101] In this embodiment, the calibration capacity is represented by CAP, and the calculation formula for the calibration capacity CAP is:

[0102] CAP = chg_cap / (100% - minimum SOC).

[0103] Wherein, chg_cap is the charging amount.

[0104] It should be noted that generally, the SOC reaches 100% only when the battery is fully charged. In this embodiment, since the battery cluster is not fully charged and the actual maximum SOC of the battery cluster is less than 100%, when 100% is used to calculate the maximum SOC of the battery cluster, in fact, a value greater than the actual maximum SOC in the battery cluster is used for capacity calibration. At this time, the calculated value of "100% - minimum SOC" will be greater than the difference between the actual maximum SOC and the minimum SOC in the battery cluster, resulting in the calculated CAP being less than the actual capacity of the battery cluster.

[0105] In this embodiment, when the full charge of the battery cluster cannot be achieved due to DOD limitations, using a value greater than the maximum SOC in the battery cluster for capacity calibration can estimate the capacity of the battery cluster.

[0106] In the above embodiments, the calculated CAP will be less than the capacity of the actual battery cluster. At this time, it is necessary to determine whether this CAP can be used as the capacity calibration value of the battery cluster. Therefore, in the embodiments of the present application, with reference to Figure 5 , based on the comparison result between the calibration capacity of the current calibration period and the current capacity value of the battery cluster, determining the capacity calibration value of the battery cluster includes:

[0107] S31. Obtain the current capacity value of the battery cluster.

[0108] Wherein, the current capacity value of the battery cluster refers to the capacity value of the currently used battery cluster, and the specific content depends on the actual configuration.

[0109] In one embodiment, when the current calibration period is the first calibration period, at this time, no capacity calibration has been performed, and there is no capacity calibration value obtained from historical calibration operations. At this time, the current capacity value is set as the rated capacity of the battery cluster.

[0110] As the capacity calibration operation of the battery cluster is continuously carried out, there will be more and more capacity calibration values of the battery cluster. The capacity calibration values of different periods are sorted in chronological order. The current capacity value can be the largest capacity calibration value obtained historically, or the capacity calibration value of the previous calibration period, or the average value of the capacity calibration values obtained from historical calibration operations, or the average value of some capacity calibration values selected from the capacity calibration values obtained from historical calibration operations. Among them, the selection principle can be to select the capacity calibration values whose difference from the average value of all capacity calibration values is less than the difference threshold to ensure the accuracy of the selected capacity calibration values.

[0111] In this embodiment, when the battery cluster needs to perform capacity calibration, a capacity calibration operation will be carried out. Each capacity calibration operation can be considered as a capacity calibration operation within a calibration period. The calibration period can be regular or irregular, depending on the actual configuration.

[0112] After the capacity calibration operation is carried out within the current calibration period, the current capacity value of the battery cluster can be obtained.

[0113] The current capacity value of the battery cluster can be stored in the storage device of the BCMU and directly obtained from the storage device of the BCMU. In addition, the current capacity value of the battery cluster can also be stored in the SMU, and the BCMU communicates with the SMU to obtain the current capacity value of the battery cluster.

[0114] S32. Determine whether the calibration capacity of the current calibration period is greater than the current capacity value; if so, execute step S33; if not, execute step S34.

[0115] Specifically, according to the above discussion, since the CAP calculated for the current calibration period is less than the capacity of the actual battery cluster, if the calibration capacity calculated for the current calibration period is greater than or equal to the current capacity value, it indicates that the current capacity value is inaccurate and calibration needs to be triggered. If the calibration capacity for the current calibration period is less than the current capacity value, calibration is not triggered, that is, the current capacity value is maintained, which can also be understood as taking the current capacity value as the capacity calibration value of the battery cluster.

[0116] S33. Take the calibration capacity of the current calibration period as the capacity calibration value of the battery cluster.

[0117] In this embodiment, when the calibration capacity for the current calibration period is greater than the current capacity value, it indicates that the capacity value estimated to be smaller than the actual capacity this time is still greater than the current capacity value. Furthermore, it indicates that the current capacity value is even smaller than the actual capacity. Then, take the calibration capacity of the current calibration period as the capacity calibration value of the battery cluster. In one implementation, the capacity calibration value of the battery cluster can be used as the latest current capacity value, or the latest current capacity value can be determined by using the above method for determining the current capacity value.

[0118] In this embodiment, when the calibration capacity for the current calibration period is equal to the current capacity value, the calibration capacity for the current calibration period can also be taken as the capacity calibration value of the battery cluster.

[0119] S34. Keep the current capacity value unchanged, that is, take the current capacity value as the capacity calibration value of the battery cluster.

[0120] In this embodiment, when the calibration capacity for the current calibration period is less than the current capacity value, since the capacity value estimated to be smaller than the actual capacity this time is on the small side, the current capacity value is still taken as the capacity calibration value of the battery cluster.

[0121] After obtaining the capacity calibration value of the battery cluster, the capacity calibration value of the battery cluster can be written into storage devices such as registers and memories, so that this data can be called later when controlling an energy storage system such as charge and discharge control.

[0122] In this embodiment, due to the limitation of DOD, the calibration condition of fully charging the battery cluster cannot be achieved. In this embodiment, even if the battery cluster cannot be fully charged and discharged, capacity estimation can still be performed. Through multiple capacity calibration operations, the calibrated capacity calibration value will gradually approach the actual capacity value of the battery cluster.

[0123] In addition, the capacity calibration method in this application has a simple calculation method, does not require the establishment of a complex calculation model, and requires less random access memory and storage resources. It is suitable for real-time calculation of capacity calibration by embedded devices and can achieve fast calibration of capacity.

[0124] Based on the embodiments of the above capacity calibration method, another embodiment of the present application provides a capacity calibration device. Referring to Figure 6 , it may include:

[0125] An acquisition module 11, configured to acquire the target state of charge of the battery cluster when the battery cluster meets the capacity calibration condition;

[0126] A determination module 12, configured to perform a charging operation on the battery cluster, and when the state of charge of the battery cluster reaches the set value of the depth of discharge or the operating state of the battery cluster changes, obtain the calibration capacity of the battery cluster in the current calibration period based on the charging amount of the battery cluster;

[0127] A calibration module 13, configured to determine the capacity calibration value of the battery cluster based on the comparison result between the calibration capacity in the current calibration period and the current capacity value of the battery cluster.

[0128] In one implementation, the acquisition module 11 includes:

[0129] A first determination sub-module, configured to determine that the battery cluster meets the capacity calibration condition when the state of charge of the battery cells in the battery cluster is in the linear region and the static duration of the battery cells reaches the specified time;

[0130] A first acquisition sub-module, configured to acquire the state of charge of each battery cell in the battery cluster;

[0131] The first determination sub-module is further configured to use the minimum state of charge as the target state of charge of the battery cluster.

[0132] In one implementation, the first acquisition sub-module is specifically configured to:

[0133] Acquire the open-circuit voltage of each battery cell in the battery cluster, and determine the state of charge corresponding to the open-circuit voltage of the battery cell according to the corresponding relationship between the open-circuit voltage and the state of charge.

[0134] In one implementation, the determination module 12 includes:

[0135] A second acquisition sub-module, configured to acquire the charging amount of the battery cluster;

[0136] A second determination sub-module, configured to determine the difference between the preset value and the target state of charge;

[0137] The second determination sub-module is further configured to use the ratio of the charging amount to the difference as the calibration capacity of the battery cluster in the current calibration period.

[0138] In one implementation, the calibration module 13 includes:

[0139] A third acquisition sub-module, configured to acquire the current capacity value of the battery cluster; wherein, when the current calibration period is the first calibration period, the current capacity value is the rated capacity of the battery cluster;

[0140] A third determination sub-module, configured to use the calibration capacity of the current calibration period as the capacity calibration value of the battery cluster when the calibration capacity of the current calibration period is greater than or equal to the current capacity value.

[0141] In one implementation, the third determination sub-module is further configured to use the current capacity value as the capacity calibration value of the battery cluster when the calibration capacity of the current calibration period is less than the current capacity value.

[0142] In one implementation, the state of charge of the battery cluster reaching the set discharge depth includes:

[0143] The state of charge of at least one battery cell in the battery cluster reaches the set maximum discharge depth;

[0144] The change in the operating state of the battery cluster includes: the battery cluster switches from the charging state to the discharging state.

[0145] In this embodiment, when the battery cluster meets the capacity calibration condition, the target state of charge of the battery cluster is acquired, and the battery cluster is charged. When the state of charge of the battery cluster reaches the set discharge depth or the operating state of the battery cluster changes, the calibration capacity of the battery cluster in the current calibration period is obtained based on the charge amount of the battery cluster, and the capacity calibration value of the battery cluster is determined based on the comparison result between the calibration capacity of the current calibration period and the current capacity value of the battery cluster. That is, in this application, when the state of charge of the battery cluster reaches the set discharge depth or the operating state of the battery cluster changes, the capacity calibration operation of the battery cluster can be performed, avoiding the problem that the battery cluster cannot be fully charged and discharged due to the discharge depth limitation, and thus the battery cluster capacity calibration cannot be achieved during full charge and discharge.

[0146] It should be noted that for the working processes of each module and sub-module in this embodiment, please refer to the corresponding descriptions in the above embodiments.

[0147] Based on any of the above embodiments, another embodiment of the present application provides a capacity calibration device, including at least one processor and a memory connected to the processor, wherein:

[0148] The memory is used to store a computer program;

[0149] The processor is configured to execute the computer program so that the electronic device can implement the above capacity calibration method.

[0150] The capacity calibration device in this embodiment can be the above-mentioned BCMU or the like.

[0151] Another implementation of this application discloses an energy storage system, including a battery cluster and the above-mentioned capacity calibration device.

[0152] In one implementation, when the capacity calibration device is the above-mentioned BCMU, as Figure 1 shown, the capacity calibration device can respond to the control instructions of the SMU and control the operating state of the battery cluster connected to the BCMU. For the specific implementation process, refer to the corresponding description above.

[0153] This application embodiment also provides a computer program product, including computer-readable instructions. When the computer-readable instructions run on an electronic device, the electronic device can implement any capacity calibration method provided by this application embodiment.

[0154] This application embodiment also provides a computer-readable storage medium. The storage medium carries one or more computer programs. When the one or more computer programs are executed by an electronic device, the electronic device can implement any capacity calibration method provided by this application embodiment.

[0155] The above description of the disclosed embodiments enables those skilled in the art to implement or use this application. Various modifications to these embodiments will be obvious to those skilled in the art. The general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application will not be limited to the embodiments shown herein, but will be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A capacity calibration method, characterized in that, Including: When the battery cluster meets the capacity calibration condition, obtaining the target state of charge of the battery cluster; Performing a charging operation on the battery cluster, and when the state of charge of the battery cluster reaches the set value of discharge depth or the operating state of the battery cluster changes, obtaining the calibration capacity of the battery cluster in the current calibration period based on the charging amount of the battery cluster; Determining the capacity calibration value of the battery cluster based on the comparison result between the calibration capacity in the current calibration period and the current capacity value of the battery cluster.

2. The capacity calibration method according to claim 1, wherein The step of, when the battery cluster meets the capacity calibration condition, obtaining the target state of charge of the battery cluster includes: When the state of charge of the battery cells in the battery cluster is in the linear region and the static time of the battery cells reaches the specified time, determining that the battery cluster meets the capacity calibration condition; Obtaining the state of charge of each battery cell in the battery cluster; Taking the minimum state of charge as the target state of charge of the battery cluster.

3. The capacity calibration method according to claim 2, characterized in that The step of obtaining the state of charge of each battery cell in the battery cluster includes: Obtaining the open-circuit voltage of each battery cell in the battery cluster; Determining the state of charge corresponding to the open-circuit voltage of the battery cell according to the correspondence between the open-circuit voltage and the state of charge.

4. The capacity calibration method according to claim 1, wherein The step of obtaining the calibration capacity of the battery cluster in the current calibration period based on the charging amount of the battery cluster includes: Obtaining the charging amount of the battery cluster; Determining the difference between the preset value and the target state of charge; Taking the ratio of the charging amount to the difference as the calibration capacity of the battery cluster in the current calibration period.

5. The capacity calibration method according to claim 1, wherein The step of determining the capacity calibration value of the battery cluster based on the comparison result between the calibration capacity in the current calibration period and the current capacity value of the battery cluster includes: Obtaining the current capacity value of the battery cluster; wherein, when the current calibration period is the first calibration period, the current capacity value is the rated capacity of the battery cluster; When the calibration capacity in the current calibration period is greater than or equal to the current capacity value, taking the calibration capacity in the current calibration period as the capacity calibration value of the battery cluster.

6. The capacity calibration method according to claim 5, characterized in that When the calibration capacity in the current calibration period is less than the current capacity value, it further includes: Taking the current capacity value as the capacity calibration value of the battery cluster.

7. The capacity calibration method according to claim 1, wherein The state of charge of the battery cluster reaching the set value of discharge depth includes: The state of charge of at least one battery cell in the battery cluster reaches the set value of maximum discharge depth; The change in the operating state of the battery cluster includes: the battery cluster switches from the charging state to the discharging state.

8. A capacity calibration device, characterized in that, Including: An acquisition module, configured to obtain the target state of charge of the battery cluster when the battery cluster meets the capacity calibration condition; A determination module, configured to perform a charging operation on the battery cluster, and when the state of charge of the battery cluster reaches the set value of discharge depth or the operating state of the battery cluster changes, obtaining the calibration capacity of the battery cluster in the current calibration period based on the charging amount of the battery cluster; A calibration module, configured to determine the capacity calibration value of the battery cluster based on the comparison result between the calibration capacity in the current calibration period and the current capacity value of the battery cluster.

9. A capacity calibration device, characterized in that, Including at least one processor and a memory connected to the processor, wherein: The memory is used to store a computer program; The processor is used to execute the computer program, so that the electronic device can implement the capacity calibration method described in any one of claims 1 to 7.

10. A energy storage system, characterized in that, It includes a battery cluster and the capacity calibration device described in claim 9.

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