A battery state of charge calibration method and device based on short-time static voltage

Abstract

The application relates to the technical field of battery management, and discloses a battery state of charge calibration method and device based on short-time static voltage, which selects a pre-stored reference discharge OCV table or a reference charging OCV table according to the judgment of the battery static state and the stable charging and discharging direction before static, obtains a target SOC according to the current lowest single voltage, and only executes calibration when the current SOC and the target SOC meet preset direction conditions, otherwise, the current SOC remains unchanged. The application aims to utilize the voltage information after short-time static of the battery, quickly corrects the SOC error accumulated by ampere-hour integration method, does not need long-time static required by the traditional open circuit voltage method, continuously performs calibration during the static process, considers the accuracy and timeliness of calibration, can effectively correct the SOC after short-time static, and significantly improves the availability of the energy storage system and the SOC estimation accuracy.

Description

Technical Field

[0001] This invention relates to the field of battery management technology, and in particular to a method and apparatus for calibrating the state of charge of a battery based on short-time resting voltage. Background Technology

[0002] In existing battery management systems, the open-circuit voltage (OCV) method is widely regarded as one of the most reliable methods for calibrating the state of charge (SOC). Its basic principle lies in utilizing the definite correspondence between battery terminal voltage and remaining capacity to correct for accumulated errors in ampere-hour integration through a lookup table. However, this method faces several long-standing technical bottlenecks in practical engineering applications.

[0003] Based on battery operating characteristics, after a battery is charged and left to rest, polarization slowly subsides, and the battery voltage gradually decreases over time, eventually stabilizing at the open-circuit voltage (OCV). Conversely, after a battery is discharged and left to rest, polarization slowly subsides, and the battery voltage gradually increases over time, eventually stabilizing at the OCV. Therefore, traditional OCV calibration requires the battery to undergo a full resting period of 2 to 4 hours to ensure that the polarization voltage generated during charging and discharging completely dissipates, thus obtaining a truly stable open-circuit voltage value. This stringent time condition is particularly critical in commercial and industrial energy storage systems, as energy storage devices often need to maintain continuous power supply or respond to dispatch commands at any time. Allocating several hours of resting time will significantly reduce system availability and operational economics.

[0004] Secondly, for lithium iron phosphate (LFP) batteries, which are widely used in the current energy storage field, the voltage at the end of the inherent voltage plateau region in the SOC range of 25% to 95% changes very slowly with SOC. The OCV-SOC mapping relationship lacks sufficient sensitivity in this region. Even after sufficient resting, a small voltage measurement deviation may lead to a significant SOC estimation error. This makes it difficult for the calibration accuracy of the traditional OCV method in the plateau region to meet the actual needs.

[0005] Furthermore, the timing of triggering existing calibration strategies is extremely limited. Calibration operations can only be performed in an absolutely static state where the battery is completely unloaded and polarization is completely eliminated. It is impossible to effectively intervene in the relatively static stage when the battery still has some polarization voltage. This greatly reduces calibration opportunities, resulting in SOC errors not being corrected for a long time in many actual operating scenarios.

[0006] Furthermore, from the perspective of user experience, frequently requiring system operators to proactively arrange long-term shutdowns for calibration not only disrupts normal charging and discharging scheduling plans but also increases the complexity of operation and maintenance management and labor costs. This calibration mode, which relies on manual intervention, is clearly not feasible, especially for unattended energy storage sites.

[0007] To overcome these limitations, several technical solutions have been proposed in recent years. For example, patent CN121741499A attempts to determine the degree of polarization decay by monitoring the voltage change rate in real time. However, this method still requires waiting for the voltage gradient to drop to a set threshold before calibration can be triggered, and it does not achieve a substantial reduction in time. Another type of solution, such as CN121454344A, attempts to extrapolate the steady-state OCV value by analyzing the morphological characteristics of the voltage relaxation curve. Although it can theoretically shorten the waiting time, this type of method relies on relatively complex mathematical modeling and parameter identification, making the algorithm implementation cumbersome. Furthermore, it is highly sensitive to voltage sampling noise and changes in relaxation characteristics caused by battery aging, making it difficult to guarantee robustness and reliability in practical engineering.

[0008] In summary, due to the inherent electrochemical characteristics of lithium-ion batteries—voltage relaxation decreases after charging and recovers after discharging—the terminal voltage changes slowly with polarization during battery resting, and the State of Charge (SOC) cannot be corrected instantaneously. If only a single calibration is performed, residual calibration deviations will occur due to incomplete voltage stabilization, leading to continuous SOC drift over time. The current battery management technology field urgently needs an online SOC calibration solution that can significantly shorten calibration resting time, does not rely on complex calculation models, and possesses good anti-interference capabilities and engineering applicability, thus simultaneously considering calibration accuracy, system availability, and ease of implementation. Summary of the Invention

[0009] Therefore, the technical problem to be solved by the present invention is to overcome the problems of low efficiency, poor accuracy and difficulty in engineering implementation of online SOC calibration caused by long-term static placement, low sensitivity of the platform area and limited calibration opportunities in the prior art.

[0010] To address the aforementioned technical problems, this invention provides a battery state-of-charge calibration method based on short-time resting voltage, comprising: Real-time monitoring of the working status of the battery pack to be calibrated; when the battery pack to be calibrated is detected to enter a static state, the current time is obtained as the detection time. Obtain the lowest single-cell voltage and current state of charge of the battery pack to be calibrated at the time of testing; Based on the charging and discharging state of the battery pack to be calibrated during the preset working period before the detection time, the stable working state of the battery pack to be calibrated is obtained; if the stable working state is a stable discharging state, the reference discharging OCV table is used as the target lookup table; if the stable working state is a stable charging state, the reference charging OCV table is used as the target lookup table. Based on the lowest single cell voltage of the battery pack to be calibrated, the target state of charge of the battery pack to be calibrated is obtained from the target lookup table. Based on the stable operating state of the battery pack to be calibrated, the current state of charge and the target state of charge, SOC calibration is performed hourly starting from the current moment. Based on the lowest single cell voltage after calibration, a new target state of charge is obtained, and SOC calibration continues until the preset termination condition is reached, thus completing the battery state of charge calibration of the battery pack to be calibrated. The SOC calibration is performed at each time step. At each time step, the following steps are taken: if the stable operating state is a stable discharge state and the current state of charge is less than the target state of charge, then the actual state of charge of the battery pack to be calibrated is calibrated to the target state of charge; if the stable operating state is a stable charging state and the current state of charge is greater than the target state of charge, then the actual state of charge of the battery pack to be calibrated is calibrated to the target state of charge; otherwise, the battery pack to be calibrated is not calibrated.

[0011] Preferably, when the absolute value of the total current of the battery pack to be calibrated is detected to be lower than the preset resting current threshold for a first preset time, the battery pack to be calibrated is identified as entering a resting state.

[0012] Preferably, the first preset time is 5 minutes, and the preset static current threshold is 0.05C.

[0013] Preferably, obtaining the lowest single-cell voltage and current state of charge of the battery pack to be calibrated at the time of testing includes: Collect the terminal voltage of all the cells connected in series in the battery pack to be calibrated, and select the minimum value as the lowest single cell voltage of the battery pack to be calibrated. Read the state of charge value calculated by the BMS of the battery pack to be calibrated using ampere-hour integration, and use it as the current state of charge of the battery pack to be calibrated.

[0014] Preferably, the stable operating state of the battery pack to be calibrated is obtained based on its charge and discharge state during a preset working period before the testing time, including: If the battery pack to be calibrated is continuously charged with a charging current not lower than the preset operating current during the preset working period before the testing time, the stable working state of the battery pack to be calibrated is the stable charging state. If the battery pack to be calibrated continues to discharge at a discharge current not lower than the preset operating current during the preset working period before the testing time, the stable working state of the battery pack to be calibrated is the stable discharge state.

[0015] Preferably, the preset working period is 10 minutes and the preset working current is 0.1C.

[0016] Preferably, the acquisition of the reference discharge OCV meter and the reference charge OCV meter includes: The battery pack to be calibrated is discharged at a constant current under specific operating conditions at a standard ambient temperature to multiple preset SOC nodes. The discharge is stopped after each preset SOC node is reached, and the battery is left to stand until the rate of change of the terminal voltage is lower than the preset change threshold. The stable voltage of each preset SOC node at the end of the stand is recorded and its corresponding true SOC is recorded as the target state of charge for each preset SOC node, forming a reference discharge OCV table. The battery pack to be calibrated is charged at a constant current under specific operating conditions to multiple preset SOC nodes at standard ambient temperature. Charging is stopped after each preset SOC node is reached, and the battery is left to stand until the rate of change of the terminal voltage is lower than a preset threshold. The stable voltage of each preset SOC node at the end of the stand is recorded along with its corresponding true SOC. This serves as the target state of charge for each preset SOC node, forming a reference charging OCV table.

[0017] Preferably, the preset termination condition includes: The total time from the detection time to the current time is greater than the preset resting time. Alternatively, the current time will reach the next working time of the battery pack to be calibrated.

[0018] Preferably, if the total time from the detection time to the current time is greater than the preset resting time, then a precise calibration is performed on the battery pack to be calibrated to calibrate the current state of charge of the battery pack to be calibrated to the target state of charge.

[0019] This embodiment also provides a battery state-of-charge calibration device based on short-time static voltage, including: The voltage acquisition module is used to acquire the operating voltage of the battery pack to be calibrated in real time in order to obtain the lowest single-cell voltage. The current acquisition module is used to monitor the charging and discharging currents of the battery pack to be calibrated in real time. The memory is used to store the reference discharge OCV meter and the reference charge OCV meter; The microprocessor, which is communicatively connected to the voltage acquisition module, the current acquisition module, and the memory, is used to calibrate the battery pack to be calibrated based on the battery state-of-charge calibration method based on short-time resting voltage as described above.

[0020] Compared with the prior art, the above-described technical solution of the present invention has the following advantages: The battery state-of-charge (SOC) calibration method based on short-term resting voltage described in this invention abandons the stringent requirement of the traditional open-circuit voltage method, which requires waiting 2-4 hours for the polarization voltage to completely dissipate. It can trigger effective calibration logic using the voltage information after the battery has been resting for a short time. This eliminates the need for energy storage systems to schedule long downtime maintenance windows. The SOC correction can be automatically completed during routine operation intervals such as charge-discharge transitions and planned short-term shutdowns. This greatly improves the continuous operation capability and equipment utilization of industrial and commercial energy storage systems and reduces the economic losses caused by calibration downtime.

[0021] Based on the fundamental electrochemical characteristics of lithium-ion batteries—voltage relaxation decreases after charging and voltage relaxation recovers after discharging—this invention distinguishes and stores a reference discharge OCV table and a reference charge OCV table. By selecting the corresponding OCV table for lookup based on the working state before resting, it avoids the lookup error caused by neglecting the relaxation direction in traditional single-table solutions. This makes the voltage-SOC mapping relationship under short-term rest more accurate and reliable, and solves the calibration deviation caused by the difference in relaxation direction from a physical mechanism perspective, providing a solid data foundation for rapid calibration.

[0022] Meanwhile, the present invention adopts a continuous approximation calibration strategy. As the resting time increases, the SOC will be gradually and continuously corrected to the true value according to the voltage relaxation trend. This effectively maintains the stability of the BMS output parameters and the smooth transition of the system control strategy, avoids the impact of numerical changes on the energy management strategy, and improves the user experience. Attached Figure Description

[0023] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein: Figure 1 This is a flowchart of the steps of the battery state-of-charge calibration method based on short-time static voltage of the present invention; Figure 2 This is a schematic diagram illustrating the principle of the battery state-of-charge calibration method based on short-time static voltage provided by the present invention. Detailed Implementation

[0024] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0025] Reference Figure 1 The flowchart of the battery state of charge calibration method based on short-time static voltage of the present invention is shown below, and the specific steps are shown in S101 to S105.

[0026] S101: Real-time monitoring of the working status of the battery pack to be calibrated. When the battery pack to be calibrated is detected to enter a static state, the current time is obtained as the detection time.

[0027] In this embodiment, when the absolute value of the total current of the battery pack to be calibrated is detected to be lower than a preset resting current threshold for a first preset time, the battery pack to be calibrated is determined to have entered a resting state. In this embodiment, the first preset time is 5 minutes, and the preset resting current threshold is 0.05C.

[0028] S102: Obtain the lowest single-cell voltage and current state of charge of the battery pack to be calibrated at the time of testing, including: Collect the terminal voltage of all the cells connected in series in the battery pack to be calibrated, and select the minimum value as the lowest single cell voltage of the battery pack to be calibrated. Read the state of charge value calculated by the BMS of the battery pack to be calibrated using ampere-hour integration, and use it as the current state of charge of the battery pack to be calibrated.

[0029] S103: Based on the charging and discharging state of the battery pack to be calibrated during the preset working period before the detection time, obtain the stable working state of the battery pack to be calibrated; if the stable working state is a stable discharging state, then use the reference discharge OCV table as the target lookup table; if the stable working state is a stable charging state, then use the reference charging OCV table as the target lookup table.

[0030] In this embodiment, if the battery pack to be calibrated is continuously charged with a charging current not lower than the preset operating current during a preset working period before the detection time, the stable working state of the battery pack to be calibrated is the stable charging state; if the battery pack to be calibrated is continuously discharged with a discharging current not lower than the preset operating current during a preset working period before the detection time, the stable working state of the battery pack to be calibrated is the stable discharging state.

[0031] Specifically, the preset working period is 10 minutes, and the preset working current is 0.1C.

[0032] In this embodiment, the acquisition of the reference discharge OCV meter and the reference charge OCV meter includes: The battery pack to be calibrated is discharged at a constant current under specific operating conditions at a standard ambient temperature to multiple preset SOC nodes. The discharge is stopped after each preset SOC node is reached, and the battery is left to stand until the rate of change of the terminal voltage is lower than the preset change threshold. The stable voltage of each preset SOC node at the end of the stand is recorded and its corresponding true SOC is recorded as the target state of charge for each preset SOC node, forming a reference discharge OCV table. The battery pack to be calibrated is charged at a constant current under specific operating conditions to multiple preset SOC nodes at standard ambient temperature. Charging is stopped after each preset SOC node is reached, and the battery is left to stand until the rate of change of the terminal voltage is lower than a preset threshold. The stable voltage of each preset SOC node at the end of the stand is recorded along with its corresponding true SOC. This serves as the target state of charge for each preset SOC node, forming a reference charging OCV table.

[0033] This invention is based on a dual OCV meter mechanism, which distinguishes and uses a reference charging OCV meter and a reference discharging OCV meter, fundamentally solving the problem of voltage-SOC correspondence differences caused by different relaxation directions. This is a prerequisite for achieving short-term static calibration.

[0034] S104: Based on the lowest single-cell voltage of the battery pack to be calibrated, obtain the target state of charge of the battery pack to be calibrated from the target lookup table.

[0035] S105: Based on the stable operating state of the battery pack to be calibrated, the current state of charge and the target state of charge, start from the current moment and perform SOC calibration hour by hour. Based on the lowest single cell voltage after calibration, obtain the new target state of charge and continue to perform SOC calibration until the preset end condition is reached, and complete the battery state of charge calibration of the battery pack to be calibrated. The SOC calibration is performed at each time step. At each time step, the following steps are taken: if the stable operating state is a stable discharge state and the current state of charge is less than the target state of charge, then the actual state of charge of the battery pack to be calibrated is calibrated to the target state of charge; if the stable operating state is a stable charging state and the current state of charge is greater than the target state of charge, then the actual state of charge of the battery pack to be calibrated is calibrated to the target state of charge; otherwise, the battery pack to be calibrated is not calibrated.

[0036] To ensure that the SOC deviation remains within a very small range during each start-up, shutdown, and operation of the equipment, this embodiment of the invention adopts a time-by-time iterative calibration mechanism during the entire static period: at each moment of short static period, the lowest single-cell voltage is refreshed synchronously, the latest target state of charge is obtained by looking up the table again, and the SOC value is gradually corrected step by step, continuously approaching the true SOC value as the voltage relaxes, and continuously suppressing the accumulation of deviation.

[0037] This invention directly designs calibration logic based on the fundamental electrochemical principle of lithium-ion batteries: charging relaxation voltage drop and discharging relaxation voltage rise. The physical principles are clear, the logic is rigorous, avoiding black-box models and ensuring high reliability. Simultaneously, it sets three judgment conditions: resting state and time, stable operating state, and comparison of the current state of charge with the target state of charge. Calibration is only performed when there is an interpretable deviation between the estimated true SOC corresponding to the measured voltage and the current integrated SOC (i.e., a falsely high SOC after charging or a falsely low SOC after discharging). This effectively prevents erroneous calibration when the voltage is not yet stable and polarization voltage still exists, plugging logical loopholes.

[0038] Meanwhile, the time-by-time calibration in this embodiment expands the effective calibration opportunities from long periods of absolute stillness to short periods of relative stillness, significantly improving the calibration frequency and timeliness, which helps to keep the SOC estimation error within a small range. Furthermore, as short-term calibration continues, the SOC will be slowly calibrated to the accurate value as the voltage changes, effectively reducing the occurrence of SOC abrupt changes due to calibration.

[0039] The preset end condition in this embodiment is that the total time from the detection time to the current time is greater than the preset resting time; or, the current time reaches the next working time of the battery pack to be calibrated.

[0040] In this embodiment, if the total duration from the detection time to the current time is greater than the preset rest time, the battery pack to be calibrated will be precisely calibrated to calibrate the current state of charge of the battery pack to be calibrated to the target state of charge.

[0041] Reference Figure 2 The diagram illustrates the principle of the battery state-of-charge (SOC) calibration method based on short-term resting voltage provided by this invention. After the calibration process begins, the current lowest single-cell voltage and the SOC estimated by the BMS are first obtained. Then, it is determined whether the resting state condition is met. If so, it is further determined whether the battery was in a stable charging state before resting. This determination branch guides the process to select different OCV-SOC lookup tables (using the discharging OCV table for charging and the charging OCV table for discharging) to obtain the target SOC. Next, by comparing the current SOC with the target SOC (the current SOC should be greater than the target SOC after charging for calibration, and less than the target SOC after discharging for calibration), it is determined whether to perform the calibration operation. If the condition is met, the current SOC value is replaced with the target SOC value.

[0042] Specifically, in this embodiment, when performing SOC calibration, the state of the battery pack is monitored in real time, and the calibration process is triggered when it is detected that the battery pack enters a standing state; the lowest cell voltage V_cell of the current battery pack and the state of charge SOC_cur currently estimated by the BMS are obtained; then, it is determined whether the battery pack is in a stable working state before standing; and a corresponding OCV-SOC lookup table is selected according to the state before standing: if the battery pack is in a stable discharge state before standing, a reference discharge OCV table is used to look up the corresponding target SOC (SOC_target_dischg) according to V_cell; if the battery pack is in a stable charging state before standing, a reference charge OCV table is used to look up the corresponding target SOC (SOC_target_chg) according to V_cell; subsequently, it is determined whether the standing time is greater than 2 hours, if it is greater than 2 hours, precise calibration is directly performed, if it is less than 2 hours, the current SOC_cur is compared with the target SOC_target, and whether to perform calibration is determined according to a preset logic; the preset logic is: if the battery pack is in a discharge state before standing and SOC_cur < SOC_target_dischg, calibrate SOC to SOC_target_dischg; if the battery pack is in a charging state before standing and SOC_cur > SOC_target_chg, calibrate SOC to SOC_target_chg; in other cases, SOC_cur remains unchanged.

[0043] The present invention utilizes the inherent physical characteristic that the terminal voltage of a lithium-ion battery relaxes over time (drops after charging and rises after discharging) after charging / discharging stops, combines pre-calibrated OCV-SOC lookup tables for different relaxation directions, and can make a logical judgment on whether SOC calibration is required after the battery is standing for a short time (e.g., 30 minutes); moreover, the calibration is continuously performed during the standing process, and SOC will continuously approach the real SOC as the standing time increases. This calibration method implements fuzzy calibration for short-time standing of the battery, also takes into account precise calibration for long-time standing, and at the same time ensures that SOC changes slowly during the calibration process, instead of the sudden SOC change in conventional calibration methods.

[0044] Based on the above embodiments, in the embodiment of the present invention, the battery state of charge calibration method based on short-time standing voltage provided by the present invention is used to perform SOC calibration on a battery pack; this embodiment is described by taking a 314Ah lithium iron phosphate battery pack used for industrial and commercial energy storage as an example, and the specific calibration process includes: S201: Data preparation; when the battery pack leaves the factory, the "reference charge OCV table" and "reference discharge OCV table" are completely calibrated at 25°C by a charge and discharge tester, and burned into the BMS memory of the battery pack; S202: System operation; stop after the battery pack is charged at a constant current of 0.5C until the BMS displays that the current state of charge SOC_cur is 15%; make the battery enter the standby state; S203: Trigger judgment; the BMS detects that the total current is lower than 0.05C for 5 consecutive minutes, and determines that it enters the "static state". At the same time, query the historical record to confirm that the 10 minutes before standing still are all in a discharge state, and the current is greater than 0.1C, so it is determined that the battery pack is in a "stable discharge state" before standing still; S204: Table lookup and judgment; obtain the lowest cell voltage V_cell=3.235V after standing still for 30 minutes; according to the judgment that it is a discharge state before standing still, select the reference discharge OCV table for table lookup, and obtain the corresponding target state of charge SOC_target_dischg as 16%; S205: Logic calibration; compare SOC_cur (15%) < SOC_target_dischg (16%), which satisfies the calibration condition after discharge standing still (the current displayed value is less than the real value reflected by the voltage). Therefore, the BMS calibrates the displayed SOC from 15% to 16%; S206: Continuous calibration; after the battery stands still for 60 minutes, the lowest cell voltage V_cell of the battery pack rises back to 3.241V, which corresponds to 17% of the discharge OCV, and the displayed SOC is calibrated from 16% to 17%; S207: After only 30 minutes of standing still at the end of discharge, the system completes an upward correction of SOC, with a correction amount of 1%. After standing still for 60 minutes, another 1% upward correction of SOC is completed.

[0045] This embodiment timely corrects the falsely low SOC that may be caused by coulombic efficiency and measurement errors in ampere-hour integration, and avoids the subsequent over-discharge risk or misjudgment of energy management strategy that may be caused by too low SOC estimation.

[0046] The reference discharge OCV table and reference charge OCV table used in this embodiment can be calibrated and obtained by yourself, or can be the reference table provided by the manufacturer when the battery pack leaves the factory. When calibrating by yourself, after discharging / charging the battery pack to a certain SOC point under a specific working condition, let it stand still for a sufficient time (such as 4 hours) until the voltage is completely stable, record the corresponding relationship between the voltage and the real SOC, and the obtained table can simulate the end point of voltage relaxation rise / fall after discharging / charging.

[0047] Based on the above embodiment, after the battery pack is left standing for 30 minutes, the reference discharge OCV table is queried according to the voltage, and the target state of charge SOC_target_dischg is obtained as 13%; at this time, after comparison, SOC_cur (15%)>SOC_target_dischg (13%), which does not satisfy the calibration condition of "SOC_cur < SOC_target". This situation may be caused by insufficient standing time, and the polarization voltage has not fully dissipated, resulting in the measured voltage still being low, and thus the SOC_target obtained from table lookup is also low; in this case, calibration is not performed to prevent misoperation, and the calibration window will be retained until the next standing that meets the conditions occurs. Then, after continuing to stand for 2 hours, the voltage rebounds, and the SOC_target_dischg obtained by querying the reference discharge OCV table according to the voltage is 14%. At this time, the precise calibration condition of standing for 2 hours is satisfied, and it is displayed that the SOC is calibrated to 14%.

[0048] Further, in this embodiment, for a battery pack whose SOC_target is in a voltage plateau (e.g., 25%-95%), calibration may not be performed according to actual conditions to avoid mis-calibration.

[0049] The present invention achieves fast and reliable calibration of SOC by introducing a dual OCV table mechanism based on relaxation direction and a triple judgment logic, and skillfully utilizes the voltage information of the battery after short-time standing in engineering. This method does not require additional hardware cost, has low algorithm complexity, can be embedded into existing BMS software, can effectively improve the estimation accuracy of battery SOC and system availability in applications such as energy storage and electric vehicles, and has high practical value and promotion prospects.

[0050] Based on the above embodiments, the embodiment of the present invention further provides a battery state of charge calibration device based on short-time standing voltage, comprising: a voltage acquisition module, configured to collect the working voltage of the battery pack to be calibrated in real time, so as to obtain the lowest cell voltage; a current acquisition module, configured to monitor the charging current and discharging current of the battery pack to be calibrated in real time; a memory, configured to store a reference discharge OCV table and a reference charge OCV table; a microprocessor, which is in communication connection with the voltage acquisition module, the current acquisition module and the memory, and is configured to calibrate the battery pack to be calibrated based on the battery state of charge calibration method based on short-time standing voltage as described above.

[0051] The battery state-of-charge (SOC) calibration method based on short-term resting voltage described in this invention abandons the stringent requirement of the traditional open-circuit voltage method, which requires waiting 2-4 hours for the polarization voltage to completely dissipate. It can trigger effective calibration logic using the voltage information after the battery has been resting for a short time. This eliminates the need for energy storage systems to schedule long downtime maintenance windows. The SOC correction can be automatically completed during routine operation intervals such as charge-discharge transitions and planned short-term shutdowns. This greatly improves the continuous operation capability and equipment utilization of industrial and commercial energy storage systems and reduces the economic losses caused by calibration downtime.

[0052] This invention is based on the fundamental electrochemical characteristics of lithium-ion batteries: voltage relaxation decreases after charging and voltage relaxation recovers after discharging. It distinguishes and stores a reference discharge OCV table and a reference charge OCV table. By selecting the corresponding OCV table based on the operating state before resting, it avoids the lookup error caused by neglecting the relaxation direction in traditional single-table solutions. This makes the voltage-SOC mapping relationship more accurate and reliable under short resting periods, solving the calibration deviation caused by differences in relaxation direction from a physical mechanism perspective, and providing a solid data foundation for rapid calibration. Simultaneously, this invention employs a continuous approximation calibration strategy. As the resting time increases, the SOC is gradually and continuously corrected to the true value according to the voltage relaxation trend, effectively maintaining the stability of BMS output parameters and the smooth transition of system control strategies. This avoids the impact of numerical abrupt changes on energy management strategies and improves the user experience.

[0053] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0054] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0055] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0056] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0057] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for calibrating the state of charge of a battery based on short-time resting voltage, characterized in that, include: The working status of the battery pack to be calibrated is monitored in real time. When the battery pack to be calibrated is detected to enter a static state, the current time is obtained as the detection time. Obtain the lowest single-cell voltage and current state of charge of the battery pack to be calibrated at the time of testing; Based on the charging and discharging state of the battery pack to be calibrated during a preset working period before the detection time, the stable working state of the battery pack to be calibrated is obtained. If the stable operating state is the stable discharge state, then the reference discharge OCV table is used as the target lookup table. If the stable operating state is the stable charging state, then the reference charging OCV table is used as the target lookup table. Based on the lowest single cell voltage of the battery pack to be calibrated, the target state of charge of the battery pack to be calibrated is obtained from the target lookup table. Based on the stable operating state of the battery pack to be calibrated, the current state of charge and the target state of charge, SOC calibration is performed hourly starting from the current moment. Based on the lowest single cell voltage after calibration, a new target state of charge is obtained, and SOC calibration continues until the preset termination condition is reached, thus completing the battery state of charge calibration of the battery pack to be calibrated. During the time-by-time SOC calibration, each time step includes: if the stable operating state is a stable discharge state and the current state of charge is less than the target state of charge, then the actual state of charge of the battery pack to be calibrated is calibrated to the target state of charge; if the stable operating state is a stable charging state and the current state of charge is greater than the target state of charge, then the actual state of charge of the battery pack to be calibrated is calibrated to the target state of charge; otherwise, the battery pack to be calibrated is not calibrated.

2. The battery state-of-charge calibration method based on short-time static voltage according to claim 1, characterized in that, When the absolute value of the total current of the battery pack to be calibrated is detected to be lower than the preset resting current threshold for a first preset time, the battery pack to be calibrated is identified as entering the resting state.

3. The battery state-of-charge calibration method based on short-time static voltage according to claim 2, characterized in that, The first preset time is 5 minutes, and the preset static current threshold is 0.05C.

4. The battery state-of-charge calibration method based on short-time static voltage according to claim 1, characterized in that, Obtain the lowest single-cell voltage and current state of charge of the battery pack to be calibrated at the time of testing, including: Collect the terminal voltage of all the cells connected in series in the battery pack to be calibrated, and select the minimum value as the lowest single cell voltage of the battery pack to be calibrated. Read the state of charge value calculated by the BMS of the battery pack to be calibrated using ampere-hour integration, and use it as the current state of charge of the battery pack to be calibrated.

5. The battery state-of-charge calibration method based on short-time static voltage according to claim 1, characterized in that, Based on the charge and discharge states of the battery pack to be calibrated during a preset working period before the testing time, the stable working state of the battery pack to be calibrated is obtained, including: If the battery pack to be calibrated is continuously charged with a charging current not lower than the preset operating current during the preset working period before the testing time, the stable working state of the battery pack to be calibrated is the stable charging state. If the battery pack to be calibrated continues to discharge at a discharge current not lower than the preset operating current during the preset working period before the testing time, the stable working state of the battery pack to be calibrated is the stable discharge state.

6. The battery state-of-charge calibration method based on short-time static voltage according to claim 5, characterized in that, The preset working period is 10 minutes, and the preset working current is 0.1C.

7. The battery state-of-charge calibration method based on short-time resting voltage according to claim 1, characterized in that, The acquisition of the reference discharge OCV meter and the reference charge OCV meter includes: The battery pack to be calibrated is discharged at a constant current under specific operating conditions at a standard ambient temperature to multiple preset SOC nodes. The discharge is stopped after each preset SOC node is reached, and the battery is left to stand until the rate of change of the terminal voltage is lower than the preset change threshold. The stable voltage of each preset SOC node at the end of the stand is recorded and its corresponding true SOC is recorded as the target state of charge for each preset SOC node, forming a reference discharge OCV table. The battery pack to be calibrated is charged at a constant current under specific operating conditions to multiple preset SOC nodes at standard ambient temperature. Charging is stopped after each preset SOC node is reached, and the battery is left to stand until the rate of change of the terminal voltage is lower than a preset threshold. The stable voltage of each preset SOC node at the end of the stand is recorded along with its corresponding true SOC. This serves as the target state of charge for each preset SOC node, forming a reference charging OCV table.

8. The battery state-of-charge calibration method based on short-time resting voltage according to claim 1, characterized in that, The preset termination conditions include: The total time from the detection time to the current time is greater than the preset resting time. Alternatively, the current time will reach the next working time of the battery pack to be calibrated.

9. The battery state-of-charge calibration method based on short-time resting voltage according to claim 8, characterized in that, If the total time from the detection time to the current time is greater than the preset rest time, then a precise calibration will be performed on the battery pack to be calibrated, and the current state of charge of the battery pack to be calibrated will be calibrated to the target state of charge.

10. A battery state-of-charge calibration device based on short-time static voltage, characterized in that, include: The voltage acquisition module is used to acquire the operating voltage of the battery pack to be calibrated in real time in order to obtain the lowest single-cell voltage. The current acquisition module is used to monitor the charging and discharging currents of the battery pack to be calibrated in real time. The memory is used to store the reference discharge OCV meter and the reference charge OCV meter; The microprocessor, which is communicatively connected to the voltage acquisition module, the current acquisition module, and the memory, is used to calibrate the battery pack to be calibrated based on the battery state-of-charge calibration method based on short-time static voltage as described in any one of claims 1 to 9.

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