Battery soc calibration method, battery management system, and vehicle

Abstract

This application provides a battery SOC calibration method, a battery management system, and a vehicle. The battery SOC calibration method includes: calculating the real-time charging capacity of the battery in response to the start of battery charging; determining a calibration curve for the current battery SOC based on the real-time charging capacity; wherein the calibration curve at least reflects the mapping relationship between battery voltage and battery SOC; and calibrating the battery SOC based on the calibration curve. Based on the above, by calculating the real-time charging capacity in response to the start of battery charging, and determining a calibration curve reflecting the mapping relationship between battery voltage and SOC based on the real-time charging capacity, and then calibrating the SOC based on the calibration curve, a more accurate battery voltage-SOC mapping relationship can be dynamically selected as the calibration basis according to the actual charging progress of the battery during the charging process. This effectively eliminates the accumulated error of ampere-hour integration, improves the accuracy of SOC estimation, and enhances the real-time performance and adaptability of SOC calibration.

Description

Technical Field

[0001] This application relates to the field of battery management, specifically to a battery SOC calibration method, a battery management system, and a vehicle. Background Technology

[0002] In the field of power battery management, accurate estimation of the state of charge (SOC) is crucial for optimizing battery performance and ensuring system energy efficiency and safety.

[0003] To meet this requirement, existing technologies typically employ the ampere-hour integration method. However, this method is prone to cumulative errors. To eliminate these errors, existing technologies often use voltage-SOC calibration curves for calibration. However, this method only triggers calibration when the battery is fully charged, and cannot trigger calibration in non-fully charged scenarios. Furthermore, existing technologies often use preset fixed calibration curves during charging, leading to a decrease in calibration accuracy. In summary, the battery SOC calibration methods of related technologies suffer from a lack of adaptive calibration and low calibration accuracy. Summary of the Invention

[0004] In view of this, this application aims to provide a battery SOC calibration method, a battery management system, and a vehicle to solve the problems of lack of adaptive calibration and low calibration accuracy in related technologies.

[0005] In a first aspect, this application provides a battery SOC calibration method, comprising: calculating the real-time charging capacity of the battery in response to the start of charging; determining the current calibration curve of the battery SOC based on the real-time charging capacity; wherein the calibration curve at least reflects the mapping relationship between the battery voltage and the battery SOC; and calibrating the battery SOC based on the calibration curve.

[0006] Optionally, the calibration curve of the current battery SOC is determined based on the real-time charging capacity, including: obtaining the reference calibration curve of the battery SOC; obtaining the current switching capacity point of the battery; and determining the current calibration curve of the battery SOC based on the real-time charging capacity, the reference calibration curve, and the switching capacity point; wherein the switching capacity point is determined based on the product between the capacity coefficient and the rated capacity of the battery, and the capacity coefficient is a real number greater than 0 and less than 1.

[0007] Optionally, the current calibration curve of the battery SOC is determined based on the real-time charging capacity, the reference calibration curve, and the switching capacity point, including: obtaining the compensation calibration curve of the battery SOC; when the real-time charging capacity is greater than or equal to the switching capacity point, selecting the reference calibration curve as the calibration curve; when the real-time charging capacity is less than the switching capacity point, selecting the compensation calibration curve as the calibration curve.

[0008] Optionally, the battery SOC is calibrated according to the calibration curve, including: acquiring the real-time voltage of the battery; when the real-time voltage reaches the calibration point, calibrating the battery SOC according to the calibration curve; after calibration, acquiring the next calibration point, and performing the step of determining the current calibration curve of the battery SOC based on the real-time charging capacity.

[0009] Optionally, obtaining the next calibration point includes: obtaining the current operating parameters of the battery; calculating the next calibration point based on the operating parameters; wherein the operating parameters include at least the battery's real-time current, real-time temperature, and real-time SOC.

[0010] Optionally, the calibration point includes an initial calibration point, which is determined before the battery begins charging.

[0011] Optionally, the method further includes: constructing a reference calibration curve for battery SOC; and constructing a compensation calibration curve for battery SOC based on the reference calibration curve.

[0012] Optionally, constructing a compensation calibration curve for battery SOC based on a reference calibration curve includes: obtaining the voltage deviation between the battery voltage under different charging conditions and the corresponding battery voltage in the reference calibration curve; and compensating for the voltage deviation to construct a compensation calibration curve.

[0013] In a second aspect, this application provides a battery management system, including: a power battery; and a controller connected to the power battery and configured to perform the battery SOC calibration method described in the first aspect above.

[0014] Thirdly, this application provides a vehicle including: the battery management system described in the second aspect above.

[0015] Based on the above, the real-time charging capacity is calculated in response to the start of battery charging, and a calibration curve reflecting the mapping relationship between battery voltage and SOC is determined based on the real-time charging capacity. Then, the SOC is calibrated based on this calibration curve. This allows for the dynamic selection of a more accurate mapping relationship between battery voltage and SOC as the calibration basis according to the actual charging progress of the battery during the charging process. This effectively eliminates the accumulated error of ampere-hour integration, improves the accuracy of SOC estimation, and enhances the real-time performance and adaptability of SOC calibration. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this disclosure or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0017] Figure 1This is a schematic flowchart of the battery SOC calibration method provided in the embodiments of this disclosure.

[0018] Figure 2 This is provided by the embodiments of this disclosure. Figure 1 A flowchart illustrating step S12.

[0019] Figure 3 This is provided by the embodiments of this disclosure. Figure 1 A flowchart of step S13.

[0020] Figure 4 This is another schematic diagram of the battery SOC calibration method provided in the embodiments of this disclosure.

[0021] Figure 5 This is a schematic diagram of the structure of the battery management system provided in an embodiment of this disclosure.

[0022] Figure 6 This is a schematic diagram of the vehicle structure provided in the embodiments of this disclosure. Detailed Implementation

[0023] The technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. Based on the embodiments of this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.

[0024] Where there is no conflict, the various embodiments of this disclosure and the features thereof in the embodiments may be combined with each other.

[0025] As used herein, the term “and / or” includes any and all combinations of one or more related enumerated entries.

[0026] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. As used herein, the singular forms “a” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will also be understood that when the terms “comprising” and / or “made of” are used in this specification, the presence of the stated feature, integral, step, operation, element, and / or component is specified, but the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or groups thereof is not excluded. Words such as “connected” or “linked” are not limited to physical or mechanical connections but can include electrical connections, whether direct or indirect.

[0027] Unless otherwise specified, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art. It will also be understood that terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant art and this disclosure, and will not be interpreted as having an idealized or overly formal meaning, unless expressly so defined herein.

[0028] Currently, in battery management systems, the ampere-hour integration method is commonly used as the basic calculation method to accurately estimate the battery's state of charge (SOC). This method calculates the change in battery capacity by integrating the current during charging or discharging over time, and then combines this with the initial SOC to deduce the current SOC. Its basic working principle is to use a current sensor to collect current values ​​in real time, and multiply the current value by the time step in each sampling period and then sum them up to obtain the cumulative capacity.

[0029] However, when the ampere-hour integration method is applied to real-world conditions where the initial charging capacity is uncertain and the charging process may not achieve full charging, this approach inherently relies on periodic full-charge calibration to eliminate current sampling errors and integration accumulation errors. However, in actual charging, the initial SOC varies and the charging termination point occurs earlier than expected, resulting in the battery rarely undergoing a complete cycle from full discharge to full charge. This makes it difficult to meet the conditions for periodic full-charge calibration. When full-charge calibration is missing, the accumulated error will continue to increase, directly manifesting as the estimated SOC gradually deviating from the true value. For example, in a short-term charging scenario where the battery starts charging at approximately 30% SOC and stops charging at approximately 80%, the mapping relationship between voltage and SOC shifts with the initial state and charging process, making the fixed mapping curve unable to accurately correspond, leading to increased SOC estimation errors, and even resulting in artificially high or low values.

[0030] Since the cumulative error of the ampere-hour integration method is essentially the result of open-loop calculation, its only closed-loop correction method relies on voltage calibration reset at the time of full charge. However, the battery voltage response trajectory differs under different initial SOCs and different charging depths. A fixed voltage-state-of-charge calibration curve cannot cover this difference, thus introducing new calibration deviations under non-full charge conditions.

[0031] This invention proposes a different technical approach: calculating the real-time charging capacity during the charging process and dynamically selecting a calibration curve reflecting the mapping relationship between battery voltage and SOC based on this capacity, thus replacing the fixed curve calibration method. In this way, the system can autonomously adapt the calibration curve according to the charging state, ensuring that the voltage-state-of-charge correspondence remains consistent with the current charging history. Specifically, it provides a curve selection method based on real-time charging capacity to solve the problem of inaccurate mapping of fixed calibration curves under non-full-charge conditions, thereby reducing the accumulated error of ampere-hour integration, decreasing dependence on full-charge calibration, and improving calibration accuracy.

[0032] It should be noted that the battery SOC calibration method of this application can be widely applied to various systems with battery power supply or energy storage functions, especially suitable for scenarios that require high-precision estimation and dynamic calibration of the remaining battery capacity under incomplete charging or non-standard initial charge conditions. For example, this solution can be integrated into the battery management system of new energy vehicles (such as pure electric vehicles, hybrid vehicles, fuel cell vehicles, etc.) to improve the reliability of SOC estimation of on-board power batteries under all operating conditions. It can also be deployed in the battery management chips or modules of various consumer electronic devices (such as smartphones, laptops, portable power supplies, etc.) to optimize the problem of inaccurate power display caused by frequent shallow charging and discharging in daily use. In addition, this technology is also applicable to industrial energy storage systems, power tools, drones, robots, and aerospace vehicles, which have stringent requirements for battery energy management and safety monitoring. Any device or system containing rechargeable batteries that requires SOC calibration through voltage-charging capacity mapping can obtain the corresponding technical effects through reasonable adaptation and transplantation of the technical solution of this application.

[0033] See Figure 1 , Figure 1 This is a schematic flowchart of a battery SOC calibration method provided in this embodiment. The method includes the following steps: Step S11: In response to the start of battery charging, calculate the real-time charging capacity of the battery.

[0034] In this application, real-time charging capacity refers to the capacity value calculated in real time from the moment charging begins, using ampere-hour integration or a similar charge accumulation method. Specifically, during battery charging, a current sensor collects the charging current in real time, and the Battery Management System (BMS) integrates the charging current over time to obtain the cumulative charge received from the start of the current charging to the current moment, which is then used as the real-time charging capacity. Therefore, real-time charging capacity can quantitatively reflect the amount of charge received by the battery, and its value is continuously updated as the charging process progresses.

[0035] In one embodiment, a separate ampere-hour integrator can be configured in the BMS to read and accumulate current sampling values ​​at fixed intervals, thereby obtaining the real-time charging capacity. In other embodiments, the calculation method for real-time charging capacity may also include a hardware accumulation method based on a coulomb counter, or a hybrid calculation method combining open-circuit voltage correction, as long as it can reflect the charging amount in real time.

[0036] Step S12: Determine the current calibration curve of the battery SOC based on the real-time charging capacity.

[0037] Among them, the calibration curve at least reflects the mapping relationship between battery voltage and battery SOC.

[0038] Specifically, due to the influence of factors such as different initial SOC, different temperatures, and different charging rates, the battery voltage-SOC relationship curve will deviate from the ideal curve of full charging starting from 0% SOC. If a fixed battery voltage-SOC mapping curve is always used to calibrate the SOC, cumulative errors will be introduced.

[0039] This application autonomously selects the calibration curve currently in use based on the real-time charging capacity, reflecting the initial state of the current charge. In one embodiment, the calibration curve can be represented as a two-dimensional or three-dimensional mapping table between battery voltage and State of Charge (SOC), a formula-fitted curve, or a data set combining table lookup and interpolation algorithms, as long as the corresponding SOC value can be found based on the current battery voltage. In other embodiments, the calibration curve not only reflects the mapping relationship between battery voltage and SOC, but also at least further reflects the mapping relationship between one or more of the battery temperature and current and SOC. For example, the calibration curve can be a three-dimensional lookup table including the temperature dimension, or a four-dimensional mapping relationship simultaneously including temperature and current, to improve the accuracy of SOC estimation under wide temperature ranges or high-current dynamic operating conditions.

[0040] Step S13: Calibrate the battery SOC based on the calibration curve.

[0041] Specifically, calibrating the battery's State of Charge (SOC) involves replacing or merging the SOC value estimated from the current ampere-hour integration with a mapped SOC value corresponding to the battery voltage obtained from a selected calibration curve through table lookup or calculation, thereby directly eliminating accumulated errors. For example, the system monitors the battery's voltage state in real time during charging. When it determines that the real-time voltage corresponds to a certain feature point (e.g., a calibration point) on the calibration curve, it triggers an SOC calibration operation.

[0042] In one embodiment, the battery voltage value, such as the maximum single-cell voltage Vmax, is first acquired in real time. Then, Vmax is compared with the SOC value corresponding to that voltage in the calibration curve. When a certain trigger condition is met, the current SOC is corrected to the queried SOC value. Furthermore, the trigger condition may include the voltage reaching a preset calibration point or the accumulated capacity reaching a certain threshold.

[0043] Based on the above method, the battery SOC calibration method provided in this application calculates the real-time charging capacity in response to the start of battery charging, and determines a calibration curve reflecting the mapping relationship between battery voltage and SOC based on the real-time charging capacity. Then, the SOC is calibrated based on the calibration curve, so that a more accurate voltage-SOC relationship can be dynamically selected as the calibration basis according to the actual charging progress of the battery during the charging process. This effectively eliminates the accumulated error of ampere-hour integration when full charging is not required, improves the SOC estimation accuracy under non-full charging conditions, and avoids the limitation of relying on full charging calibration, thereby improving the real-time performance and adaptability of SOC calibration.

[0044] To further optimize the feasibility of selecting the calibration curve in the above embodiments, this application also provides the following preferred solutions. In a preferred embodiment, see [reference needed]. Figure 2 , Figure 2 This is provided by the embodiments of this disclosure. Figure 1 The flowchart for step S12 shows that determining the current battery SOC calibration curve based on the real-time charging capacity in step S12 specifically includes the following steps: Step S121: Obtain the reference calibration curve of battery SOC.

[0045] In this application, the reference calibration curve generally refers to the voltage-SOC mapping relationship established based on the standard full charge process of a battery from a completely discharged state (SOC of 0%) to a fully charged state (SOC of 100%). For example, it may include, but is not limited to, initial multi-dimensional charging curves constructed based on standard charge and discharge test data at different temperatures and charging rates.

[0046] One method for obtaining this curve is to pre-generate and store it in the memory of the battery management system, as a reference benchmark for subsequently judging the degree of deviation of the current charging state from the standard full charge state.

[0047] Step S122: Obtain the current switching capacity point of the battery.

[0048] In this application, the switching capacity point generally refers to the comparison threshold used to determine the calibration curve, which is determined by the product of the capacity coefficient and the rated capacity of the battery, where the capacity coefficient is a real number greater than 0 and less than 1.

[0049] Rated capacity refers to the capacity that a battery can release from a fully charged state to the cutoff voltage under standard conditions. The capacity coefficient can be determined based on multiple charge-discharge test data of the battery cell. Its value is related to the cell model and aging degree, and can be adjusted within a small range. For example, in the first calibration, 'a' can be ≥0.7, and in the second and subsequent calibrations, 'a' can be ≥0.75.

[0050] Specifically, the switching capacity point is a quantitative threshold used to distinguish between full charging and insufficient charging. If the amount of charge added during the charging process reaches or exceeds the switching capacity point, it can be considered that the current charge is sufficient to make the battery voltage trajectory approach the standard full charge path; otherwise, it indicates that the current charge is a shallow charge or the initial SOC is high, and its voltage trajectory will deviate significantly from the reference calibration curve.

[0051] Step S123: Determine the current calibration curve of the battery SOC based on the real-time charging capacity, the reference calibration curve, and the switching capacity point.

[0052] Specifically, based on the current charging progress parameters, the system dynamically determines and selects a mapping relationship that best matches the actual state of the battery, serving as the basis for subsequent SOC calibration. This step performs a calibration curve selection decision by comparing the real-time charging capacity with the switching capacity point. For example, in one embodiment, if the real-time charging capacity is greater than or equal to the switching capacity point, it is determined that the charging process is deep enough and the battery voltage trajectory is close to the standard full charge path, so the reference calibration curve obtained in step S121 is selected. If the real-time charging capacity is less than the switching capacity point, it is determined to be a shallow charge or a non-standard starting state, and the reference calibration curve is no longer applicable, so another specially modified calibration curve (such as pre-compensated for voltage deviation under different starting conditions) needs to be selected.

[0053] To provide targeted compensation for non-full charge conditions such as short-term and shallow charging, in a preferred embodiment, step S123 determines the current battery SOC calibration curve based on the real-time charging capacity, the reference calibration curve, and the switching capacity point, including the following steps: Step S1231: Obtain the compensation calibration curve of battery SOC.

[0054] In this application, the term "compensation calibration curve" generally refers to a calibration curve that corrects for voltage trajectory deviations caused by differences in the charging process under different operating conditions such as different charging capacities, charging durations, and charging SOCs. For example, it may include, but is not limited to, a compensation calibration curve constructed by superimposing voltage deviations measured under different charging capacities, charging durations, and charging SOCs on a reference calibration curve.

[0055] Step S1232: When the real-time charging capacity is greater than or equal to the switching capacity point, select the reference calibration curve as the calibration curve.

[0056] Specifically, when the real-time charging capacity is greater than or equal to the switching capacity point, it indicates that the initial SOC of this charge is low, and the charged amount of electricity is sufficient to make the battery voltage trajectory approach the standard full charge path. At this time, the reference calibration curve can be used.

[0057] Step S1233: When the real-time charging capacity is less than the switching capacity point, select the compensation calibration curve as the calibration curve.

[0058] Specifically, when the real-time charging capacity is less than the switching capacity point, it indicates that this is a shallow charge or the initial SOC is high, and the voltage trajectory deviates significantly from the reference calibration curve. In this case, a compensation calibration curve should be used.

[0059] To further automate the calibration process and implement step-by-step corrections, this application also optimizes the calibration execution process as follows. In a preferred embodiment, see [reference needed]. Figure 3 , Figure 3 This is provided by the embodiments of this disclosure. Figure 1 The flowchart of step S13 shows that the battery SOC calibration based on the calibration curve in step S13 specifically includes the following steps: Step S131: Obtain the real-time voltage of the battery.

[0060] Specifically, the real-time voltage of a battery is usually obtained by continuously and frequently collecting the battery's terminal voltage or individual cell voltage through the front-end sampling circuit of the battery management system.

[0061] Step S132: When the real-time voltage reaches the calibration point, calibrate the battery SOC according to the calibration curve.

[0062] The calibration point is essentially a preset voltage characteristic point. When the real-time voltage meets the preset or dynamically determined calibration point conditions (i.e., the voltage value is equal to or exceeds the characteristic point), it means that the battery has entered a voltage plateau region suitable for SOC correction. At this time, the system does not directly use the result of ampere-hour integration, but instead uses the currently selected calibration curve as a basis to obtain the standard SOC value corresponding to the real-time voltage through table lookup or calculation, and uses this value as the corrected SOC result.

[0063] In one embodiment, it is assumed that the first calibration point voltage preset by the BMS is 3.60V. When the real-time voltage obtained in step S131 reaches and exceeds 3.60V at a certain moment, the BMS determines that the calibration condition is triggered. The BMS performs multi-dimensional lookup and linear interpolation in the two-dimensional table of the reference calibration curve stored in the memory, using the current real-time voltage of 3.61V as input, to find that the SOC value corresponding to this voltage is 42.8%. The BMS immediately replaces the SOC value estimated by the current ampere-hour integration (e.g., 43.5%) with 42.8%, completes the SOC correction action, and updates the corrected SOC value to the state of charge recording unit.

[0064] Optionally, the calibration point includes an initial calibration point, which is determined before the battery begins charging.

[0065] Specifically, the initial calibration is a preset calibration point set before charging begins. This initial calibration point can be a preset voltage value related to the battery state. During charging, the BMS continuously monitors the voltage, and when the voltage rises to this initial calibration point, the first SOC calibration is triggered.

[0066] Step S133: After calibration is completed, obtain the next calibration point and perform the step of determining the current calibration curve of the battery SOC based on the real-time charging capacity.

[0067] Specifically, after completing this calibration, the system automatically transitions to the identification process for the next calibration point and returns to the step of dynamically determining the calibration curve, forming a segmented and iterative closed-loop control. This ensures that throughout the entire charging cycle, each calibration can reselect the most suitable mapping relationship based on the latest charging progress status and perform corrections at appropriate trigger moments, ultimately achieving continuous and accurate SOC tracking. In summary, through this closed-loop operation of triggering calibration - calculating the next calibration point - re-determining the curve, SOC errors are corrected segmentally and systematically, avoiding the problem of error accumulation after a single calibration.

[0068] The dynamic determination of the next calibration point requires consideration of the battery's current operating state to ensure that the triggering time of the calibration point matches the battery's actual thermal and electrical characteristics. In a preferred embodiment, obtaining the next calibration point in step S133 specifically includes the following steps: Step S1331: Obtain the current operating parameters of the battery.

[0069] The operating parameters include at least the battery's real-time current, real-time temperature, and real-time SOC.

[0070] Specifically, the operating parameters are a comprehensive reflection of the battery's current electrochemical state and operating conditions. These parameters are usually obtained by the front-end sampling and internal computing unit of the battery management system, which reads the current values ​​from the current sensor, temperature sensor, and state of charge recording module, respectively.

[0071] Step S1332: Calculate the next calibration point based on the operating parameters.

[0072] Specifically, the next calibration point is essentially a characteristic voltage value (or SOC value) that matches the current battery state. Its calculation relies on pre-calibrated multi-dimensional lookup tables or functional relationships. The calculation process typically takes real-time current, real-time temperature, and real-time SOC as inputs, and outputs a voltage value through lookup tables combined with algorithms such as linear interpolation or polynomial fitting.

[0073] In one embodiment, the BMS internally stores a three-dimensional lookup table with "temperature-current-SOC" as input and "voltage point number" as output. Using the parameters obtained in step S1331, for example, real-time temperature = 28°C, real-time current = 50A, and real-time SOC = 42.8% as input, the BMS first locates two temperature levels (25°C and 30°C), two current levels (0.3C and 0.6C), and two SOC levels (40% and 45%). Then, using a three-dimensional linear interpolation algorithm, it calculates the next calibration point voltage value of 3.68V under this operating condition. The BMS stores this value as the voltage value to trigger the next calibration round and returns to the real-time voltage monitoring process, waiting for the real-time voltage to reach 3.68V to initiate the next SOC calibration.

[0074] The calibration curves involved in the above embodiments are all pre-built and stored in the BMS before the online calibration process is started. In a preferred embodiment, see [link to preferred embodiment]. Figure 4 , Figure 4 This is another schematic flowchart of the battery SOC calibration method provided in this disclosure embodiment, which further includes: Step S41: Construct a baseline calibration curve for battery SOC.

[0075] In one embodiment, battery cells of the same batch and model are selected and discharged to 0% SOC. Then, they are charged at a constant current rate of 0.5C (50A if the rated capacity is 100Ah) in a 25°C constant temperature chamber until full charge conditions are met (e.g., voltage rises to 4.2V and current drops to 0.05C). Throughout the charging process, the charging voltage V and cumulative charging capacity are recorded every second, and the SOC is calculated by the ratio of cumulative charging capacity to rated capacity. The above steps are repeated at different temperatures (e.g., -10°C, 0°C, 25°C, 45°C) and different rates (e.g., 0.2C, 0.5C, 1C, 2C) to obtain multiple sets of battery voltage-SOC data. Finally, the BMS organizes this data into a multi-dimensional lookup table indexed by temperature and rate, with SOC as the row and battery voltage as the column, and stores it in non-volatile memory. For example, at 25°C and 0.5C, the reference battery voltage corresponding to SOC=50% is 3.75V; at 45°C and 1C, the reference battery voltage corresponding to SOC=50% is 3.72V.

[0076] Step S42: Construct a compensation calibration curve for battery SOC based on the benchmark calibration curve.

[0077] Optionally, the step S42 of constructing the battery SOC compensation calibration curve based on the reference calibration curve may include the following steps: Step S421: Obtain the voltage deviation between the battery voltage under different charging conditions and the corresponding battery voltage in the reference calibration curve.

[0078] Different charging conditions can refer to different initial SOC, different charging capacities, different charging times, different temperatures, and different charging rates. Tests are conducted under these different charging conditions, the actual voltage trajectory of the battery is recorded, and this trajectory is compared with the battery voltage values ​​at the same temperature, charging rate, and SOC position on the benchmark calibration curve to obtain the voltage deviation.

[0079] In one embodiment, taking an initial SOC of 60% and charging at 25°C at a 0.5C rate to 10% of the rated capacity (i.e., charging 10Ah, if the rated capacity is 100Ah) as an example, during charging, when the real-time SOC reaches 65%, the measured voltage is recorded as 3.65V. The reference voltage value of the reference calibration curve constructed in step S41 at 25°C, 0.5C, and SOC=65% is found to be 3.70V. Therefore, the voltage deviation is calculated as 3.65V - 3.70V = -0.05V. The above test is repeated, changing the initial SOC (e.g., 40%, 80%), charging capacity (e.g., 20%, 30%), etc., accumulating a series of voltage deviation data points to form a multi-dimensional voltage deviation database.

[0080] Step S422: Compensate for the voltage deviation to construct a compensation calibration curve.

[0081] Specifically, the compensation method is to superimpose the voltage deviation onto the voltage value at the corresponding point on the reference calibration curve, thereby obtaining a new curve.

[0082] In one embodiment, the BMS's memory pre-stores a generated voltage deviation lookup table and a calculation formula. When the BMS determines during charging that a compensation calibration curve needs to be used (e.g., the real-time charging capacity is less than the switching capacity point), it looks up the corresponding voltage deviation ΔV based on the current real-time temperature T, real-time current I, initial charging SOC, real-time SOC value, or cumulative charging capacity, and interpolates the result. Then, the BMS reads the voltage value V0 of the reference calibration curve at the same SOC point under the current real-time temperature T and real-time current I, and calculates the compensation voltage value VC corresponding to that SOC point in real time using the formula VC = V0 + ΔV. For example, at a certain moment, the current SOC = 70%, ΔV = -0.03V, V0 = 3.85V, then the compensated voltage VC = 3.85V + (-0.03V) = 3.82V.

[0083] It should be noted that the above-described preferred embodiments can be used independently or combined to achieve the desired effects. For example, combining dynamic curve selection based on switching capacity points with adaptive calibration point calculation based on real-time parameters, while considering the coverage of both the benchmark and compensation calibration curves, can further enhance the adaptability of SOC calibration under various non-fully charged operating conditions. Furthermore, the value of the capacity coefficient is not limited to the given example and can be calibrated according to the actual cell characteristics and aging degree; the method for constructing the calibration curve is not limited to table lookup interpolation, but can also employ any form that can describe the voltage-SOC mapping relationship, such as polynomial fitting or machine learning models.

[0084] See Figure 5 , Figure 5 This is a schematic diagram of the battery management system provided in an embodiment of this disclosure. The battery management system 500 includes a power battery 510 and a controller 520. The controller 520 is connected to the power battery 510 and is configured to perform the battery SOC calibration method as described above.

[0085] See Figure 6 , Figure 6 This is a schematic diagram of the structure of a vehicle provided in an embodiment of this disclosure, wherein the vehicle 600 has a battery management system 610. The battery management system 610 is the same as the battery management system 500 described above, and will not be repeated here.

[0086] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0087] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0088] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0089] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0090] In addition, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0091] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this invention, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program verification codes, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0092] Furthermore, it should be noted that the combination of the various technical features in this case is not limited to the combination methods described in the claims of this case or the combination methods described in the specific embodiments. All technical features described in this case can be freely combined or combined in any way, unless they contradict each other.

[0093] It should be noted that the above examples are merely specific embodiments of the present invention, and the present invention is obviously not limited to the above embodiments, with many similar variations. All modifications that can be directly derived or conceived by those skilled in the art from the content disclosed in this invention should fall within the protection scope of this invention.

[0094] It should be understood that the terms "first," "second," etc., mentioned in the embodiments of the present invention are used only to more clearly describe the technical solutions of the embodiments of the present invention, and cannot be used to limit the scope of protection of the present invention.

[0095] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A battery SOC calibration method, characterized in that, include: In response to the start of battery charging, the real-time charging capacity of the battery is calculated; The calibration curve of the current state of charge (SOC) of the battery is determined based on the real-time charging capacity; wherein the calibration curve at least reflects the mapping relationship between the battery voltage and the battery SOC; The battery's SOC is calibrated based on the calibration curve.

2. The method according to claim 1, characterized in that, The step of determining the current SOC calibration curve of the battery based on the real-time charging capacity includes: Obtain the reference calibration curve of the battery's state of charge (SOC); Obtain the current switching capacity point of the battery; The current calibration curve of the battery SOC is determined based on the real-time charging capacity, the reference calibration curve, and the switching capacity point. The switching capacity point is determined based on the product of the capacity coefficient and the rated capacity of the battery, wherein the capacity coefficient is a real number greater than 0 and less than 1.

3. The method according to claim 2, characterized in that, The step of determining the current battery SOC calibration curve based on the real-time charging capacity, the reference calibration curve, and the switching capacity point includes: Obtain the compensation calibration curve of the battery's SOC; When the real-time charging capacity is greater than or equal to the switching capacity point, the reference calibration curve is selected as the calibration curve. When the real-time charging capacity is less than the switching capacity point, the compensation calibration curve is selected as the calibration curve.

4. The method according to claim 1, characterized in that, The calibration of the battery SOC according to the calibration curve includes: Obtain the real-time voltage of the battery; When the real-time voltage reaches the calibration point, the battery SOC is calibrated according to the calibration curve; After calibration is completed, obtain the next calibration point and execute the step of determining the current SOC of the battery based on the real-time charging capacity.

5. The method according to claim 4, characterized in that, The step of obtaining the next calibration point includes: Obtain the current operating parameters of the battery; Calculate the next calibration point based on the operating parameters; The operating parameters include at least the real-time current, real-time temperature, and real-time SOC of the battery.

6. The method according to claim 4, characterized in that, The calibration point includes an initial calibration point, which is determined before the battery begins charging.

7. The method according to claim 1, characterized in that, Before calculating the real-time charging capacity of the battery in response to the start of charging, the process includes: Construct a reference calibration curve for the battery's state of charge (SOC); A compensation calibration curve for the battery's state of charge (SOC) is constructed based on the benchmark calibration curve.

8. The method according to claim 7, characterized in that, The construction of the compensation calibration curve for the battery's state of charge (SOC) based on the reference calibration curve includes: Obtain the voltage deviation between the battery voltage under different charging conditions and the corresponding battery voltage in the reference calibration curve; The voltage deviation is compensated to construct the compensation calibration curve.

9. A battery management system, characterized in that, include: Power battery; The controller, connected to the power battery, is configured to perform the battery SOC calibration method as described in any one of claims 1-8.

10. A vehicle, characterized in that, include: The battery management system as described in claim 9.

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