Method and device for SOC correction of power battery

Abstract

The invention provides an SOC correction method for a power battery, and the method comprises the following steps: checking whether the power battery can successfully trigger an SOC correction function based on a dynamic voltage-SOC reference curve or not, and cannot successfully trigger a correction application condition indicating that the charging operation condition of the power battery does not meet the reference curve or not; if the SOC correction function based on the reference curve cannot be successfully triggered, when the dynamic voltage of at least one battery unit in the power battery reaches a voltage threshold value, the charging current is reduced to a current threshold value; when the dynamic voltage drops to a current threshold, a reference curve-based SOC correction function is allowed to be triggered. The invention further provides a device for correcting the SOC of the power battery and a computer program product. According to the invention, by implementing a current reduction measure, the state of the battery can be changed to enable the battery to meet the correction application condition again, and the application range of the SOC correction function is expanded.

Description

Technical Field

[0001] The present application relates to a method for correcting the state of charge (SOC) of a power battery, and also relates to a device for correcting the SOC of a power battery and a computer program product. Background Art

[0002] In a battery management system (BMS), accurately estimating the SOC is crucial for battery performance and safety. Although an SOC correction method based on a dynamic voltage-SOC curve has been proposed, it has been found that this curve drifts under different operating conditions, resulting in inaccurate correction results.

[0003] Currently, although the applicable conditions for correcting the reference curve have been explored, this is still insufficient to handle the complex situations in practical applications. Especially in a low-temperature environment, a power battery sometimes quickly approaches a fully charged state with a large current, and at this time, the current exceeds the limit and does not meet the applicable conditions for correction, making the SOC correction function unable to be successfully triggered. Especially for those battery cells that do not finally reach the cut-off voltage, the lack of this correction function will lead to inaccurate SOC estimation, which in turn affects the management and service life of the battery.

[0004] Therefore, there are still deficiencies in the existing technology in terms of SOC correction of batteries. Summary of the Invention

[0005] The purpose of the present application is to provide a method for correcting the SOC of a power battery, a device for correcting the SOC of a power battery, and a computer program product, so as to solve at least some of the problems in the existing technology.

[0006] According to the first aspect of the present application, there is provided a method for correcting the SOC of a power battery, the method including the following steps:

[0007] Step S1, for the power battery, check whether the SOC correction function based on the dynamic voltage-SOC reference curve can be successfully triggered, where the failure to trigger successfully indicates that the charging operation conditions of the power battery do not meet the applicable conditions for correction of the reference curve;

[0008] Step S2, if the SOC correction function based on the reference curve cannot be successfully triggered, then when the dynamic voltage of at least one battery cell in the power battery reaches a voltage threshold, reduce the charging current to a current threshold; and

[0009] Step S3, when the dynamic voltage drops to the current threshold, allow the triggering of the SOC correction function based on the reference curve.

[0010] This application particularly includes the following technical concepts: When the battery voltage reaches a preset threshold, by implementing a current reduction measure, the charging current is accurately regulated to a level that meets the applicable conditions for SOC correction. This measure neither prematurely interferes with the charging process nor delays until the optimal timing is missed, thereby enabling the full utilization of the dynamic voltage - SOC reference curve to perform SOC correction on the power battery and its cells. The core advantage of this method is that it can effectively trigger the SOC correction function under a wider range of charging conditions, especially during high - rate current charging and in an extended low - temperature environment. This not only significantly improves the accuracy and reliability of SOC correction but also optimizes the performance of the battery management system and enhances the adaptability and stability of the battery under complex operating conditions.

[0011] In an exemplary embodiment, step S3 includes: After the charging current is reduced to the current threshold, continue charging the power battery, and when the dynamic voltage reaches the voltage threshold for the second time, perform SOC correction with the aid of the dynamic voltage - SOC reference curve.

[0012] In an exemplary embodiment, the voltage threshold is determined in relation to the starting point of the voltage range where correction needs to be performed with the aid of the dynamic voltage - SOC reference curve, where: The voltage threshold is determined to be equal to the starting point of the voltage range; or, the voltage threshold is determined to be the starting point of the voltage range minus a predetermined margin.

[0013] In an exemplary embodiment, the dynamic voltage of at least one battery cell in the power battery reaching the voltage threshold includes: The dynamic voltage of any battery cell in the power battery reaches the voltage threshold for the first time; The average value of the dynamic voltages of multiple battery cells in the power battery reaches the voltage threshold; or, the dynamic voltage of the last battery cell in the power battery reaches the voltage threshold.

[0014] In an exemplary embodiment, the current threshold is determined to be less than the smaller of the following two values: In the dynamic voltage - SOC reference curve, the maximum allowable current value corresponding to the starting point of the SOC range; and, in the updated applicable conditions for correction, the current boundary value corresponding to the ambient temperature and initial SOC of the current charging operation conditions.

[0015] In an exemplary embodiment, the updated applicable conditions for correction are determined as follows: For the case where the SOC correction function based on the reference curve cannot be successfully triggered, when the dynamic voltage of at least one battery cell reaches the voltage threshold for the first time, different degrees of current reduction operations are adopted to make the dynamic voltage reach the voltage threshold for the second time; For each degree of current reduction, starting from the moment when the dynamic voltage reaches the voltage threshold for the second time, calculate the deviation between the dynamic voltage - SOC drift curve and the reference curve; Based on the deviation, determine the updated applicable conditions for correction.

[0016] In an exemplary embodiment, before at least step S2, the method further includes the following steps: checking the feasibility of the down-current operation based on the current ambient temperature, wherein the down-current operation is further performed in step S2 only when the ambient temperature is higher than a preset temperature threshold, otherwise it is concluded that the SOC correction of the power battery cannot be performed by means of the dynamic voltage-SOC reference curve.

[0017] In an exemplary embodiment, the method further includes the following steps: after the charging current is reduced to a current threshold, the power battery is continuously charged through a constant-current charging operation and / or a down-current charging operation until a charging termination condition is reached.

[0018] According to a second aspect of the present application, there is provided a device for SOC correction of a power battery, which includes a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor can execute the method according to the first aspect of the present application.

[0019] According to a third aspect of the present application, there is provided a computer program product, which includes computer program instructions, wherein when the computer program instructions are executed by one or more processors, the one or more processors can execute the method according to the first aspect of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Hereinafter, the present application will be described in more detail by referring to the drawings, and the principles, features and advantages of the present application can be better understood. The drawings include:

[0021] Figure 1 A flowchart showing a method for SOC correction of a power battery according to an exemplary embodiment of the present application;

[0022] Figure 2 A flowchart showing a method for SOC correction of a power battery according to another exemplary embodiment of the present application;

[0023] Figure 3 A schematic diagram schematically showing a dynamic voltage-SOC test matrix for determining the original correction applicable conditions;

[0024] Figure 4A and 4B A schematic diagram showing a dynamic voltage Vi-SOC curve in the case of performing a down-current operation at different ambient temperatures;

[0025] Figure 5 A schematic diagram showing a dynamic voltage Vi-SOC curve measured when performing a down-current operation at different down-current degrees; and

[0026] Figure 6 The structural block diagram of a device for SOC correction of a power battery according to an exemplary embodiment of the present application is shown. Detailed implementation manners

[0027] In order to make the technical problems, technical solutions and beneficial technical effects to be solved by the present application clearer, the present application will be further described in detail below in conjunction with the drawings and multiple exemplary embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application, rather than to limit the protection scope of the present application.

[0028] Figure 1 The flowchart of a method for SOC correction of a power battery according to an exemplary embodiment of the present application is shown. The method includes, for example, step S1, step S2 and step S3.

[0029] In this document, a power battery is a high-energy-density battery that provides power for an electric vehicle or other electric devices, and it is usually composed of multiple battery cells (such as battery modules or battery cores). Power batteries usually adopt lithium-ion battery technology, but the methods described herein are not limited thereto, and are also applicable to other battery types (such as lead-acid batteries) and different application scenarios (such as aircraft, ships, etc.).

[0030] In step S1, for the power battery, it is checked whether the SOC correction function based on the dynamic voltage-SOC reference curve can be successfully triggered. Among them, the failure to successfully trigger indicates that the charging operation conditions of the power battery do not meet the correction applicable conditions of the reference curve.

[0031] The dynamic voltage-SOC reference curve Vi = f(SOC) can usually be obtained through experiments or simulation under reference operating conditions. Among them, Vi represents the dynamic voltage of the battery cell, and SOC represents the state of charge of the battery cell. Exemplarily, at a reference ambient temperature of 25°C, using a constant charging rate of 0.1 starting from 0% SOC, the battery cells of the same specification in actual use are charged, and the dynamic voltage and the corresponding SOC at each time point are synchronously recorded. These recorded data points can be used to plot curves, organize into tables or construct into mathematical functions to describe the reference correspondence between the dynamic voltage of the battery cell and SOC.

[0032] The success or failure of triggering the SOC correction function based on the reference curve is closely related to the SOC correction accuracy. The dynamic voltage-SOC reference curve can only achieve the required correction accuracy under specific charging operation conditions (such as ambient temperature, initial SOC, charging rate). If outside these condition ranges, the correction using the reference curve will no longer be accurate.

[0033] Therefore, it is possible to determine whether the SOC correction function based on the reference curve can be successfully triggered by checking the current charging operation conditions. For example, if the current charging operation conditions of the power battery do not meet the correction applicable conditions of the reference curve, it is determined that the SOC correction function based on the reference curve cannot be successfully triggered. The correction applicable conditions refer to the operating range in which the reference curve can be effectively used to correct the SOC at a specific charging rate, initial SOC, SOC interval to be charged, and ambient temperature. Beyond this range, the correction result may be inaccurate. For example, if the correction applicable conditions stipulate that when the temperature is 15°C and the initial SOC is 0%, the charging rate shall not exceed 0.2C, and the current operating conditions are 15°C, the initial SOC is 0%, and the charging rate is 0.4C, it indicates that the current charging operation conditions do not meet the correction applicable conditions.

[0034] The SOC correction function can be used for individual battery cells as needed, and then the SOC of the entire power battery is re-determined based on the corrected results. For example, the minimum value, median, or average value of the corrected SOC of all battery cells can be taken as the corrected SOC of the entire power battery. In addition, the weighted average method can also be used to perform weighted calculations on the corrected SOC according to the health status of the battery cells, so as to more accurately reflect the SOC of the entire power battery.

[0035] If it is confirmed in step S1 that the SOC correction function can be successfully triggered, step S3 can be directly entered, and the SOC of the power battery is corrected using the reference curve. If the function cannot be successfully triggered, step S2 is entered to perform a current reduction operation. Specifically, when the dynamic voltage of at least one battery cell in the power battery reaches the set voltage threshold, the charging current is reduced to the current threshold. For ease of description, step S2 is further split into sub-steps S21 and S22.

[0036] In sub-step S21, it is checked whether the dynamic voltage of at least one battery cell in the power battery reaches the voltage threshold.

[0037] The power battery consists of multiple battery cells, and their voltages may vary due to individual differences, aging degrees, or different usage conditions. Therefore, there are several situations where the dynamic voltage reaches the voltage threshold: One is that as long as the dynamic voltage of any one battery cell reaches the set voltage threshold for the first time, the current reduction operation is implemented. This method can ensure the integrity of SOC correction, avoid the loss of correction opportunities for some battery cells due to too late current reduction, and ensure charging safety at the same time; Another is that when the average value of the dynamic voltages of multiple battery cells reaches the voltage threshold, the current reduction operation is implemented. This method considers the overall state of the battery pack and avoids premature current reduction caused by individual cell differences, thereby prolonging the charging time; There is also a situation where the current reduction operation is only implemented when the dynamic voltage of the last battery cell reaches the voltage threshold. This method can further shorten the charging time and ensure that the charging states of all battery cells are more balanced, avoiding insufficient charging.

[0038] The setting of the voltage threshold is to ensure the start of SOC correction at an appropriate time during battery charging, avoiding problems caused by premature or late correction. It can be determined related to the starting point of the voltage range that needs to be corrected in the dynamic voltage - SOC reference curve.

[0039] In one embodiment, if in the reference curve of a certain battery, the starting point of the voltage range for SOC correction is 3.48V, the voltage threshold can be directly set to 3.48V. When the dynamic voltage of the battery reaches this value, the current reduction operation starts. For lithium iron phosphate batteries, 3.48V is the sign of the end of the plateau period. In the voltage range below this value, the change in SOC is small and the curve is relatively flat. Therefore, it is more effective and accurate to start correction from above 3.48V. If the setting is too late, some key correction points may be missed, affecting the comprehensiveness and accuracy of the correction.

[0040] To further ensure a complete correction range, a certain margin can be set. For example, a margin of 0.05V is set, and the voltage threshold is adjusted to 3.43V (3.48V - 0.05V). When the dynamic voltage reaches 3.43V, the current reduction operation starts, which can avoid losing the initial several correction points due to reducing the current exactly at the correction starting point.

[0041] Different types of batteries (such as lithium - ion batteries, nickel - metal hydride batteries, lead - acid batteries, etc.) have different voltage - SOC characteristic curves. Therefore, the starting voltage value of the reference curve will vary due to battery type, brand, model, or usage environment. The setting of the voltage threshold can be determined according to the specific reference curve.

[0042] In sub-step S21, if the dynamic voltage of the power battery has not reached the set voltage threshold, continue charging and continuously monitor the voltage. Once the dynamic voltage reaches the voltage threshold, in sub-step S22, reduce the charging current to the current threshold, and then continue charging.

[0043] The current threshold can be set to the smaller of the following two key values:

[0044] - In the dynamic voltage - SOC reference curve, the maximum allowable current value corresponding to the starting point of the SOC range. This value is determined according to the battery characteristics and is the maximum current that the battery can withstand at a specific SOC value, reflecting the safe charging limit. For example, if the starting point of the battery SOC range is 98%, the maximum allowable charging current is 0.15C, which ensures the safety and performance of the battery.

[0045] - In the updated correction application conditions, the current boundary value corresponding to the current charging operation conditions (including ambient temperature and initial SOC): This value is obtained based on experiments and data analysis, aiming to ensure that after the current reduction operation, the state of charge of the battery can re - conform to the applicable range of the reference curve, so as to use the reference curve for accurate SOC correction. For example, when the ambient temperature is 15°C and the initial SOC is 95%, the current boundary value is set to 0.2C.

[0046] During the charging process, when the SOC of the battery reaches 98%, the current threshold is determined to be 0.15C, which is the smaller of the two key values (0.15C is less than 0.2C). This means that the charging current must be limited to below 0.15C to ensure both meeting the applicable range of the reference curve and not exceeding the safe charging current limit of the battery.

[0047] It can be envisioned that the original correction application conditions were determined under specific ambient temperature, initial SOC, and charging rate. However, after the current reduction operation, when the battery voltage first drops and then reaches the voltage threshold again, both the charging operation conditions and the battery state have changed, and the original correction application conditions are no longer applicable. Therefore, it is necessary to re - determine the correction application conditions for the new battery state after the current reduction operation, which is referred to as the updated correction application conditions in the context.

[0048] In one embodiment, the updated correction application conditions are determined as follows: when the dynamic voltage of at least one battery cell in the dynamic voltage first reaches the voltage threshold but does not meet the correction application conditions, different degrees of current reduction operations are adopted to make the dynamic voltage reach the voltage threshold for the second time. For each degree of current reduction, starting from the moment when the dynamic voltage reaches the voltage threshold for the second time, the deviation between the dynamic voltage - SOC drift curve and the reference curve is calculated. Based on the calculated deviation, the updated correction application conditions are determined. These new conditions will more accurately reflect at what degree of current reduction the reference curve can be used to correct the SOC.

[0049] For example, during the charging process, when the dynamic voltage of a certain battery cell first reaches 3.48V, the current charging rate is 0.3C, while the correction condition requires that the charging rate be less than 0.2C, so it does not meet the correction conditions. It should be noted that the initially set 0.2C is measured based on the initial conditions, and subsequent current reduction operations will change the battery state and operating conditions, so the current cannot be directly reduced to 0.2C.

[0050] To determine the appropriate degree of current reduction, for example, starting from the initial charging current of 0.3C, it can be successively tried to reduce to 0.2C, 0.15C, and 0.1C, and continue charging to observe the change in dynamic voltage. When the dynamic voltage reaches 3.48V for the second time, record the SOC value and plot the drift curve, and calculate the deviation by comparing with the reference curve. For example, the deviation is 5% at 0.2C, 3% at 0.15C, and 1% at 0.1C. According to the deviation results, the correction application conditions are updated: at this ambient temperature, reducing the current below 0.15C can use the reference curve for SOC correction. This shows that the updated current boundary value (0.15C) is different from the initial value (0.2C). In practical applications, the updated current boundary value may be less than, equal to, or greater than the initial value, depending on the actual state and operating conditions of the battery. In step S3, when the dynamic voltage drops to the current threshold, the SOC correction function based on the reference curve is allowed to be triggered.

[0051] In one embodiment, after the charging current drops to the current threshold, the power battery continues to be charged until the charging termination condition is reached.

[0052] Here, the charging termination condition refers to a series of criteria set during the battery charging process. When these conditions are met, the charging process will stop. These conditions usually include: the battery voltage reaches the set charging cut-off voltage (such as 4.2V), the charging current drops to a very small value (such as 0.05C), or the charging time reaches the preset maximum time, etc. These conditions are set to ensure that the battery will not be overcharged, thereby extending the battery life, while ensuring the safety and efficiency of charging.

[0053] The charging operation after dropping to the current threshold can be constant - current charging (charging at a fixed rate) or decreasing - current charging (gradually reducing the charging current during charging). The specific charging method can be selected according to actual requirements and safety.

[0054] Figure 2 FIG. shows a flowchart of a method for SOC correction of a power battery according to another exemplary embodiment of the present application.

[0055] Figure 2 Compared with Figure 1 a main difference is that an additional step S20 is added before step S2 to determine whether the decreasing - current operation is feasible according to the ambient temperature under the current charging operation conditions. If it is determined that the decreasing - current operation is feasible, then in the subsequent step S2, the decreasing - current operation is performed according to the Figure 1 method; if it is determined that it is not feasible, then step S2 is skipped, and it is directly concluded in step S4 that the SOC correction of the power battery and / or battery cell cannot be achieved by means of the dynamic voltage - SOC reference curve. Through this check, the reason for the inability to trigger the SOC correction function can be clarified: if it is caused by too large a current, it can be remedied by decreasing - current measures; if it is caused by too low a temperature, then the correction cannot be achieved even if the current is reduced.

[0056] In one embodiment, in the additional step S20, the feasibility of the decreasing - current operation is determined by checking whether the current ambient temperature is higher than a preset temperature threshold. Only when the ambient temperature is higher than this threshold is the decreasing - current operation confirmed to be feasible. In particular, the preset temperature threshold can be set to be lower than the lowest temperature boundary value recorded in the initial correction applicable conditions.

[0057] For example, the initially set reference - curve correction applicable conditions require that the ambient temperature must be higher than 10 °C. However, according to the updated correction applicable conditions, when the voltage threshold is reached for the second time through the decreasing - current operation, as long as the ambient temperature is higher than 8 °C, the reference curve can be used for SOC correction. This adjustment enables the reference curve to be applied in a wider low - temperature range, significantly improving the applicability and flexibility of SOC correction.

[0058] Figure 2 Compared with Figure 1Another main difference is that step S3 is split into sub-steps S31 and S32. In sub-step S31, after the down-current operation, the power battery continues to be charged, and it is monitored whether the dynamic voltage of the battery cell reaches the voltage threshold again. Due to the polarization and internal resistance characteristics of the battery, the dynamic voltage will first drop and then rise after the down-current, and quickly reach the voltage threshold again. In sub-step S32, starting from the second time the dynamic voltage reaches the voltage threshold until the entire voltage range where the charging termination condition is reached, the dynamic voltage-SOC reference curve is used for SOC correction. By limiting the correction range and timing, the correction efficiency can be improved, ensuring that the correction is implemented when the battery state meets the requirements again, and at the same time avoiding the error caused by the curve plateau period to the correction result.

[0059] For example, when the dynamic voltage of the battery first reaches 3.48V, the charging current is 0.3C, and the SOC is 95%. Since the charging current is too high and does not meet the correction condition. Therefore, the system implements a down-current operation to reduce the charging current to 0.15C. Subsequently, when the dynamic voltage reaches 3.48V for the second time, the SOC is 98%, and at this time the charging current has dropped to 0.15C, meeting the correction condition, and the reference curve can be used for SOC correction.

[0060] Figure 3 Schematically shows a schematic diagram of a dynamic voltage-SOC test matrix for determining the original correction applicable conditions.

[0061] When determining the original correction applicable conditions, it can be achieved through the following steps: First, obtain the dynamic voltage-SOC drift curves of the power battery under different charging operation conditions (including different initial SOCs, ambient temperatures, and charging rates). Then, evaluate its matching degree by calculating the deviation degree between the drift curve and the reference curve (such as using methods such as mean square error, absolute percentage error, correlation coefficient, etc.). If the deviation is less than the preset threshold, it is considered that this condition is suitable for using the reference curve for SOC correction.

[0062] Exemplarily, the reference correspondence can be defined as:

[0063] 3.48V corresponds to 98% SOC;

[0064] 3.55V corresponds to 99% SOC;

[0065] 3.65V corresponds to 100% SOC.

[0066] Figure 3Shows the test results at an initial SOC of 0% under different ambient temperatures (10°C, 15°C, 20°C, 25°C) and charge rates (0.3C, 0.2C, 0.1C). In this test matrix, no shading indicates "pass", and shading indicates "fail". If the predefined deviation degree is ±2%, the SOC corresponding to 3.48V is considered "pass" when it is between 96% and 100%.

[0067] The results show that at 10°C, all results are "fail"; at 15°C, only 0.1C "passes"; at 20°C and 25°C, 0.2C and 0.1C "pass".

[0068] The finally summarized applicable correction conditions are, for example:

[0069] Initial SOC ≥ 0%, ambient temperature ≥ 20°C, charge rate ≤ 0.2C;

[0070] Initial SOC ≥ 0%, ambient temperature ≥ 15°C, charge rate ≤ 0.1C;

[0071] Initial SOC ≥ 20%, ambient temperature ≥ 15°C, charge rate ≤ 0.3C.

[0072] In practical applications, more data points can be obtained through experiments, curve fitting, or interpolation methods to more comprehensively evaluate the correction conditions.

[0073] It should be noted that Figure 3 the applicable correction conditions obtained are based on the measurements in the original state, that is, determined without implementing the current reduction measures. If the magnitude or boundary value of the current reduction needs to be accurately determined, the updated applicable correction conditions need to be re-measured after the current reduction operation, and the relevant content will be further elaborated in Figure 5 which will be further elaborated in

[0074] Figure 4A and 4B shows a schematic diagram of the dynamic voltage Vi - SOC curve under the condition of implementing the current reduction operation at different ambient temperatures.

[0075] In the figure, arrow 401 marks the voltage threshold of the dynamic voltage (e.g., 3.48V), and arrows 402 and 403 respectively indicate the positions where the voltage reaches the threshold for the first and second times. Among them, the bold part of the curve represents the change process before the current reduction operation, and the non-bold part of the curve represents the change process after the current reduction operation.

[0076] In Figure 4AIn (an ambient temperature of 15°C), when the dynamic voltage of the battery first reaches 3.48V (the position indicated by arrow 402), the corresponding SOC is approximately 96%-97%, and the charging current is 0.4C at this time. Since the charging operation conditions at this time do not meet the corrected applicable range, there may be a large deviation between the actual SOC and the reference SOC (such as 98%), so the SOC correction function cannot be successfully triggered. Subsequently, the charging current decreases from 0.4C to 0.15C. At this time, the battery voltage first drops briefly and then rises again and reaches 3.48V for the second time (the position indicated by arrow 403). At this time, the actual SOC of the battery rises from 96% to slightly higher than 98%, and the deviation from the reference SOC does not exceed the predetermined value, so the reference curve can be used for SOC correction.

[0077] In Figure 4B (an ambient temperature of 10°C), the drift characteristics of the battery dynamic voltage-SOC curve are more significant. When the voltage threshold is first reached (the position indicated by arrow 402), the actual SOC is lower than 95%, significantly deviating from the reference value of 98%. To successfully trigger the SOC correction function, the charging current is reduced from 0.2C to 0.08C. The dynamic voltage rises again after the current reduction and reaches 3.48V for the second time (the position indicated by arrow 403), and at this time the actual SOC rises to more than 96%, so the reference curve can be used for SOC correction.

[0078] According to the original corrected applicable conditions, when the ambient temperature is 10°C, even if the charging current is smaller, the SOC correction conditions cannot be met. However, through the updated corrected applicable conditions, it is found that the applicable range of the ambient temperature can be extended to 8°C through the current reduction operation. This means that at lower temperatures, through appropriate current reduction measures, the SOC correction conditions can still be met, thus significantly improving the applicability and correction accuracy of the battery in low-temperature environments.

[0079] Figure 5 Shows a schematic diagram of the dynamic voltage Vi-SOC curve measured when the current reduction operation is implemented at different degrees of current reduction.

[0080] In the figure, arrow 500 marks the voltage threshold of the dynamic voltage (such as 3.48V), and arrow 501 marks the position where the voltage first reaches the threshold. The bolded voltage-SOC curve represents the change process before the current reduction operation, and the unbolded part represents the change process after the current reduction operation. Arrows 51, 52, and 53 respectively indicate the corresponding curve change trends at different degrees of current reduction.

[0081] As Figure 5As shown, when the dynamic voltage of the battery cell first reaches the voltage threshold (e.g., 3.48V), different degrees of current reduction operations can be performed to make the dynamic voltage reach the threshold again. Assuming the initial charging current rate is 0.4C, it is reduced to 0.2C, 0.15C, and 0.1C respectively, which correspond to Figure 5 curves 51, 52, and 53 in

[0082] . When the dynamic voltage reaches the threshold for the second time after the current reduction, record the SOC value at this time and draw the dynamic voltage - SOC curves respectively. It is observed that when reaching the threshold for the first time, the SOC is less than 95%. As the current reduction amplitude increases, the curve drifts to the right. The SOC when reaching the threshold for the second time gradually increases and is closer to 98%, and the degree of drift gradually decreases.

[0083] Figure 6 The structural block diagram of a device for SOC correction of a power battery according to an exemplary embodiment of the present application is shown.

[0084] The device 600 can be implemented, for example, as a battery management system (BMS) of a vehicle or a component thereof, and can be connected to each battery cell of the vehicle power battery in practical applications.

[0085] As Figure 6 shown, the device 600 includes a memory 610 and a processor 620, and the two can be coupled together through a bus. However, it should be understood that Figure 6 this is only an example and does not limit the scope of the present application. For example, in different application scenarios, the device 600 may also include an input interface and an output interface, which are not limited herein.

[0086] The memory 610 stores a computer program. When the computer program is executed by the processor 620, the processor 620 can execute the method for SOC correction of a power battery according to an exemplary embodiment of the present application, which has been described in detail above and will not be repeated here for the sake of brevity. The computer program instructions can be stored in a computer - readable storage medium. The computer - readable storage medium may include, for example, a high - speed random - access memory, and may also include a non - volatile memory or a volatile solid - state storage device.

[0087] The processor 620 may be a central processing unit, or may also be other general-purpose processors, digital signal processors, application-specific integrated circuits, off-the-shelf programmable gate arrays, or other programmable logic devices, etc.

[0088] It should be noted that the method features and advantages described above also apply to the device 600, and vice versa.

[0089] It can be understood that the methods of the embodiments of the present application can be implemented by computer programs / software. These software can be loaded into the working memory of the processor and, when running, are used to execute the methods according to the embodiments of the present application.

[0090] According to another embodiment of the present application, there is provided a computer program product, such as a machine (e.g., a computer) readable medium, such as a CD-ROM, which includes computer program code that, when executed, causes a computer or a processor to execute the methods according to the embodiments of the present application. The machine-readable medium is, for example, an optical storage medium or a solid-state medium supplied together with or as part of other hardware.

[0091] Although specific embodiments of the present application have been described in detail herein, they are given for purposes of explanation only and should not be considered as limiting the scope of the present application. Various substitutions, alterations, and modifications can be conceived without departing from the spirit and scope of the present application.

Claims

1. A method for SOC correction of a power battery, the method comprising the following steps: Step S1, for the power battery, checking whether the SOC correction function based on the dynamic voltage-SOC reference curve can be successfully triggered, wherein failure to successfully trigger indicates that the charging operation condition of the power battery does not meet the correction applicable condition of the reference curve; Step S2, if the SOC correction function based on the reference curve cannot be successfully triggered, when the dynamic voltage of at least one battery cell in the power battery reaches the voltage threshold, the charging current is reduced to the current threshold; and Step S3: When the dynamic voltage drops to the current threshold, the SOC correction function based on the reference curve is allowed to be triggered.

2. The method according to claim 1, wherein: The step S3 includes: after the charging current is reduced to the current threshold, continuing to charge the power battery, and performing SOC correction with the help of the dynamic voltage-SOC reference curve when the dynamic voltage reaches the voltage threshold for the second time.

3. The method according to claim 1 or 2, wherein: The voltage threshold is determined in relation to the start of a voltage range in which a correction needs to be performed with the aid of a dynamic voltage-SOC reference curve, wherein: determining the voltage threshold to be equal to the start point of the voltage range; or The voltage threshold is determined as the start point of the voltage range minus a predetermined margin.

4. The method according to any one of claims 1 to 3, wherein: The dynamic voltage of at least one battery cell in the power battery reaches a voltage threshold, including: The dynamic voltage of any battery cell in the power battery reaches the voltage threshold for the first time; The dynamic voltage average value of multiple battery cells in the power battery reaches the voltage threshold; or The dynamic voltage of the last battery cell in the power battery reaches the voltage threshold.

5. The method according to any one of claims 1 to 4, wherein: The current threshold is determined to be less than the smaller of: The maximum allowable current value corresponding to the starting point of the SOC range in the dynamic voltage-SOC reference curve; and The updated correction application conditions include the current boundary value corresponding to the ambient temperature and initial SOC of the current charging operation conditions.

6. The method according to claim 5, wherein: The updated amendment application conditions are determined in the following manner: In case that the SOC correction function based on the reference curve cannot be successfully triggered, when the dynamic voltage of at least one battery cell in the dynamic voltage reaches the voltage threshold for the first time, different degrees of current reduction operations are adopted to make the dynamic voltage reach the voltage threshold for the second time; For each current reduction degree, from the moment when the dynamic voltage reaches the voltage threshold for the second time, the deviation between the dynamic voltage-SOC drift curve and the reference curve is calculated; Based on the deviation, the updated correction application conditions are determined.

7. The method according to any one of claims 1 to 6, wherein: The method further comprises the following steps at least before step S2: The feasibility of the current reduction operation is checked based on the current ambient temperature, wherein the current reduction operation is further performed in step S2 only when the ambient temperature is higher than a preset temperature threshold, otherwise it is concluded that it is impossible to perform SOC correction on the power battery with the help of the dynamic voltage-SOC reference curve.

8. The method according to any one of claims 1 to 7, wherein: The method further includes the following steps: after the charging current is reduced to the current threshold, the power battery is continuously charged through a constant current charging operation and / or a reduced current charging operation until a charging termination condition is reached.

9. A device for SOC correction of a power battery, comprising a memory and a processor, wherein: The memory stores a computer program, and when the computer program is executed by the processor, the processor is capable of performing the method according to any one of claims 1 to 8.

10. A computer program product comprising computer program instructions, wherein: The computer program instructions, when executed by one or more processors, enable the one or more processors to perform a method according to any one of claims 1 to 8.

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