Method and apparatus for determining SOC correction application conditions for battery cells

Abstract

The invention provides a method for determining SOC correction application conditions of a battery unit. The method comprises the following steps: acquiring a reference corresponding relation between dynamic voltage and SOC of the battery unit; acquiring a drift corresponding relationship between the dynamic voltage and the SOC of the battery unit under different operation conditions, wherein the different operation conditions are different at least in the aspects of the initial SOC of the battery unit, the temperature of the environment where the battery unit is located and / or the charging rate; and determining an SOC correction application condition for performing SOC correction on the battery cell by means of the reference correspondence according to the degree of deviation between the drift correspondence and the reference correspondence. The application also proposes a method for correcting the SOC of a battery cell, a corresponding device and a computer program product. According to the SOC estimation method and device, the optimal application condition of the reference corresponding relation is identified, and application of a correction algorithm under an unsuitable working condition is avoided, so that the SOC estimation error is reduced.

Description

Technical Field

[0001] The present application relates to a method for determining applicable conditions for SOC correction of a battery cell. The present application also relates to a method for correcting the SOC of a battery cell, a device for determining applicable conditions for SOC correction of a battery cell, a device for correcting the SOC of a battery cell, and a computer program product. Background Art

[0002] In a battery management system (BMS), accurate estimation of SOC is critical to battery performance and safety. Although a SOC correction method based on a dynamic voltage-SOC curve has been proposed, studies have found that this curve will drift under different operating conditions, resulting in inaccurate correction results.

[0003] To solve this problem, the prior art proposes to measure the correction curves under different working conditions, and select the appropriate curve for SOC correction according to the current working conditions in actual use. However, since the current and voltage will continue to fluctuate in actual use, coupled with the limitation of measurement accuracy, it is challenging to select the most appropriate correction curve in real time. In addition, frequently changing correction conditions will also cause error accumulation, which will affect the robustness and reliability of the correction method.

[0004] Therefore, the prior art still has deficiencies in battery SOC correction. Summary of the invention

[0005] The purpose of the present application is to provide a method for determining applicable conditions for SOC correction of a battery cell, a method for correcting the SOC of a battery cell, a device for determining applicable conditions for SOC correction of a battery cell, a device for correcting the SOC of a battery cell and a computer program product, so as to at least solve some of the problems in the prior art.

[0006] According to a first aspect of the present application, a method for determining an applicable condition for SOC correction of a battery cell is provided, the method comprising the following steps:

[0007] Step S1: obtaining a reference corresponding relationship between the dynamic voltage and SOC of the battery cell;

[0008] Step S2: obtaining a drift correspondence between a dynamic voltage and SOC of a battery cell under different operating conditions, wherein the different operating conditions differ at least in terms of a starting SOC of the battery cell, an ambient temperature of the battery cell, and / or a charging rate; and

[0009] Step S3: Determine an applicable SOC correction condition for performing SOC correction on the battery cell with the reference corresponding relationship according to the degree of deviation between the drift corresponding relationship and the reference corresponding relationship.

[0010] The present application particularly includes the following technical concepts: By deeply analyzing the relationship between the dynamic voltage and SOC of the battery, the present application can accurately measure the deviation between the actual drift curve and the theoretical reference curve. This technology can intelligently identify the optimal conditions for the reference curve to avoid applying the correction algorithm under unsuitable working conditions, thereby reducing the error in SOC estimation. Through this intelligent means, not only the accuracy and reliability of battery management are improved, but also the overall efficiency and safety of the battery are improved. In addition, this also ensures that the battery management system can maintain efficient and stable operation under various working conditions.

[0011] In an exemplary embodiment, the step S2 includes: step S21: maintaining the ambient temperature of the battery cell at a predetermined temperature under a preset starting SOC; step S22: charging the battery cell to a cut-off voltage with a fixed charging rate; step S23: during the charging process of the battery cell, recording the dynamic voltage and charging capacity of the battery cell in real time, and calculating the test SOC value corresponding to each dynamic voltage point based on the charging capacity, starting SOC and nominal capacity of the battery cell; and, step S24: changing the operating conditions and repeating steps S21 to S23 to establish a dynamic voltage-SOC test matrix for different operating conditions.

[0012] In an exemplary embodiment, step S3 includes: determining the following operating conditions as applicable conditions for SOC correction: the degree of deviation between the drift correspondence obtained under the operating conditions and the reference correspondence is less than a predetermined threshold, wherein: for each dynamic voltage point, the test SOC value recorded in the established dynamic voltage-SOC test matrix is ​​compared with the reference SOC value in the reference correspondence, and checking whether the test SOC value is within a predefined error range of the reference SOC value, wherein the predefined error range is particularly set to ±2%; and, operating conditions that enable the test SOC values ​​corresponding to a determined number of dynamic voltage points to fall within the predefined error range of the reference SOC value are determined as applicable conditions for SOC correction.

[0013] In an exemplary embodiment, in step S3, only for a determined dynamic voltage interval, the degree of deviation between the drift correspondence and the reference correspondence is calculated and the applicable conditions for SOC correction are determined according to the degree of deviation. The determined dynamic voltage interval is particularly set to 3.48V to 3.65V.

[0014] In an exemplary embodiment, the step S3 further includes: evaluating the influence of the change trend of the operating conditions on the degree of deviation, wherein as the initial SOC in the operating conditions increases, the charging rate decreases, and the ambient temperature increases, the degree of deviation between the drift correspondence and the reference correspondence decreases; in step S3, when the degree of deviation is required to be less than or equal to 2%, the following operating conditions are determined as applicable conditions for SOC correction:

[0015] The initial SOC is greater than or equal to 0%, the ambient temperature is greater than or equal to 20°C, and the charging rate is less than or equal to 0.2C;

[0016] The initial SOC is greater than or equal to 0%, the ambient temperature is greater than or equal to 15°C, and the charging rate is less than or equal to 0.1C;

[0017] The initial SOC is greater than or equal to 20%, the ambient temperature is greater than or equal to 15°C, and the charging rate is less than or equal to 0.3C.

[0018] In an exemplary embodiment, the step S2 also includes: step S201: performing a charge and discharge test on the battery cell through a standard charge and discharge process to determine the nominal capacity of the battery cell; step S202: discharging the battery cell from a fully charged state to a preset starting SOC, wherein the discharge process is terminated by controlling the discharge power of the battery cell, and the discharge power is set according to the preset starting SOC; and / or, step S21': after adjusting the ambient temperature of the battery cell to a predetermined temperature, keeping the battery cell in a static state for a predetermined time period.

[0019] According to a second aspect of the present application, a method for correcting the SOC of a battery cell is provided, the method comprising the following steps: obtaining a measured dynamic voltage and a measured SOC of the battery cell when the charging termination condition is reached under actual operating conditions; checking whether the actual operating conditions belong to the SOC correction applicable conditions determined by the method described in the first aspect of the present application; and, in a case where it is determined that the actual operating conditions belong to the SOC correction applicable conditions, based on the reference correspondence, obtaining a theoretical SOC of the battery cell according to the measured dynamic voltage, and correcting the measured SOC of the battery cell with the help of the theoretical SOC.

[0020] According to the third aspect of the present application, a device for determining the applicable conditions for SOC correction of a battery cell is provided, 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 is capable of executing the method described in the first aspect of the present application.

[0021] According to a fourth aspect of the present application, a device for correcting the SOC of a battery cell is provided, 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 executing the method described in the second aspect of the present application.

[0022] According to the fifth aspect of the present application, a computer program product is provided, comprising computer program instructions, wherein the computer program instructions, when executed by one or more processors, enable the one or more processors to execute the method according to the first aspect of the present application and / or the method according to the second aspect of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The present application will be described in more detail below with reference to the accompanying drawings, so that the principles, features and advantages of the present application can be better understood. The accompanying drawings include:

[0024] Figure 1 A flow chart schematically shows a method for determining an applicable condition for SOC correction of a battery cell according to an exemplary embodiment of the present application;

[0025] Figure 2 Schematically shows Figure 1 A flow chart of one method step of the method shown;

[0026] Figure 3 Schematically shows Figure 1 A flow chart of another method step of the method shown;

[0027] Figure 4 Schematically shows a flow chart of a method for correcting the SOC of a battery cell according to an exemplary embodiment of the present application;

[0028] Figure 5 A schematic diagram of a dynamic voltage-SOC test matrix is ​​schematically shown;

[0029] FIG. 6A to FIG. 6E A schematic diagram of a dynamic voltage Vi-SOC curve is schematically shown;

[0030] Figure 7 A structural block diagram schematically shows a device for determining applicable conditions for SOC correction of a battery cell according to an exemplary embodiment of the present application; and

[0031] Figure 8 The structure block diagram of the device for correcting the SOC of a battery cell according to an exemplary embodiment of the present application is schematically shown. DETAILED DESCRIPTION

[0032] 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 accompanying 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 scope of protection of the present application.

[0033] Figure 1 A flowchart of a method for determining an SOC correction applicable condition of a battery cell according to an exemplary embodiment of the present application is schematically shown.

[0034] The battery cells mentioned herein may refer to, for example, lithium iron phosphate (LFP / graphite) battery cells or battery modules. These batteries are mainly used in the power system of vehicles. However, it should be understood that the methods described in this application are not limited to a specific type of battery or a specific use, but are also applicable to other types of batteries, such as lead-acid batteries, and batteries used in different application scenarios such as aircraft and ships.

[0035] like Figure 1 As shown, the method includes step S1, step S2 and step S3.

[0036] In step S1, a reference corresponding relationship between the dynamic voltage and SOC of a battery cell is obtained.

[0037] In this application, dynamic voltage refers to the voltage across the battery cell measured in real time during the battery charging and discharging process, which reflects the voltage change of the battery cell under working conditions. This voltage is the actual voltage of the battery when current flows, which is different from the voltage of the battery under no-load (open circuit) conditions.

[0038] The above-mentioned reference correspondence relationship Vi=f(SOC) can usually be obtained through experiments under reference operating conditions, where Vi represents the dynamic voltage of the battery cell and SOC represents the state of charge of the battery cell. For example, at a reference ambient temperature of 25°C, a constant charging rate of 0.1 to .3C can be used to charge the battery cells of the same specification actually used from 0% SOC, and the dynamic voltage and corresponding SOC at each time point can be recorded synchronously. These recorded data points can be used to draw curves, organize them into tables, or construct them into mathematical functions to describe the reference correspondence between the dynamic voltage and SOC of the battery cell.

[0039] In addition, it is possible to consider predetermining reference correspondences for fast charging and slow charging modes respectively, and selecting corresponding reference standards according to the adopted charging strategy in practical applications.

[0040] It should be understood that the reference operating conditions mentioned above (including temperature, charge rate and initial SOC, etc.) are exemplary, and they are intended to illustrate how to establish a reference correspondence. In actual applications, the specific values ​​of these conditions can be adjusted so that the reference correspondence can be flexibly set according to actual needs.

[0041] In step S2, a drift correspondence between the dynamic voltage and SOC of the battery cell under different operating conditions is obtained, wherein the different operating conditions differ at least in the initial SOC of the battery cell, the ambient temperature of the battery cell and / or the charging rate.

[0042] Research has shown that the relationship between the dynamic voltage and SOC of a battery can drift due to changes in ambient temperature, charge rate, and initial SOC. These variables affect the migration rate and charge transfer process of lithium ions by changing the internal chemical kinetics and physical structure of the battery, which in turn causes deviations from the standard relationship between voltage response and SOC. In order to ensure the accuracy of SOC correction, it is necessary to accurately measure the degree of this drift under different operating conditions.

[0043] In a specific embodiment, in order to study the effect of temperature on the drift of the dynamic voltage-SOC correspondence relationship of the battery separately, the ambient temperature can be changed in sequence for different charging cycles while keeping other operating conditions unchanged. For example, the temperature can be set to 10°C, 15°C, 20°C, 25°C, etc. Here, 5°C is used as the temperature interval, but other meaningful temperature intervals can also be selected according to different needs. Similarly, if you want to explore the effect of changing the charging rate on the drift of the corresponding relationship, you can charge the battery at a rate of 0.1C, 0.2C and 0.3C or a combination of multiple rates in different charging cycles. When the goal is to study the effect of the starting SOC on the curve drift, you can choose to charge the battery cell from different starting SOCs such as 0%, 20%, 50%, 80%, etc.

[0044] The specific test process of drift correspondence will be combined below Figure 2 Further elaboration.

[0045] In step S3, according to the degree of deviation between the drift correspondence and the reference correspondence, an SOC correction applicable condition for performing SOC correction on the battery cell by means of the reference correspondence is determined.

[0046] The degree of deviation can be quantified by a variety of mathematical methods, including but not limited to mean square error, standard deviation, absolute percentage error, root mean square error, correlation coefficient and cross-correlation analysis. The method to be selected depends on the characteristics of the data and the required accuracy.

[0047] In one embodiment, whether these conditions are suitable for SOC correction can be determined by checking whether the degree of deviation between the drift correspondence obtained under specific operating conditions and the reference correspondence is less than a predetermined threshold. If the deviation is less than the threshold, the operating condition is considered suitable for correction.

[0048] In another embodiment, in order to more efficiently identify all applicable operating conditions, the influence of the changing trend of the operating conditions on the degree of deviation can be further analyzed. Through this method, for example, those boundary conditions that make the deviation just reach the predetermined threshold can be preferentially determined, and all operating conditions on one side of the boundary condition can be directly divided into applicable SOC correction conditions accordingly. For example, when it is determined that the starting SOC is 0%, the ambient temperature is 20°C, and the charging rate is 0.2C, the above-mentioned degree of deviation is just equal to the predetermined threshold, and if it is found that the deviation between the drift correspondence and the reference correspondence decreases with the increase of the starting SOC, the decrease of the charging rate and the increase of the ambient temperature, then it can be directly concluded that under the conditions that the starting SOC is greater than or equal to 0%, the ambient temperature is greater than or equal to 20°C, and the charging rate is not higher than 0.2C, the reference correspondence can be effectively applied for SOC correction.

[0049] In another embodiment, in order to improve the test efficiency and reduce the necessary test points, step S3 can focus on a specific dynamic voltage interval to calculate the deviation between the drift correspondence and the reference correspondence. Particularly advantageously, the degree of deviation can be evaluated only within a selected voltage range, and the applicable conditions for SOC correction can be determined accordingly. For example, a specific dynamic voltage interval can be set to 3.48V to 3.65V. The selection of such an interval is based on the characteristics of the battery type (such as a lithium iron phosphate battery), for example, because in the voltage interval below 3.48V, the change in SOC is relatively small, and the voltage-SOC curve tends to be stable. Therefore, directly analyzing the voltage interval above 3.48V can more effectively identify key drift deviations.

[0050] After determining the applicable conditions for SOC correction, these conditions can be stored and integrated into the vehicle's battery management system (BMS), or saved in the cloud for remote access. In this way, during the actual use of the battery, the BMS can refer to these preset conditions to determine whether the current operating conditions are suitable for SOC correction, thereby ensuring the accuracy of SOC estimation and the effectiveness of the battery management system.

[0051] Figure 2 Schematically shows Figure 1 A flow chart of the method steps of the method shown. Figure 2 In the embodiment shown, Figure 1 Step S2 of the method shown comprises a series of sub-steps.

[0052] In the preparation stage, a battery to be tested including a plurality of battery units (such as battery cells or battery modules) may be provided.

[0053] In step S201, the battery cell is charged and discharged through a standard charge and discharge process to determine the nominal capacity C0 of the battery cell. For example, the battery cell can be charged to a charge cut-off voltage at a set of charge rates that decrease with SOC (such as 0.5C, 0.3C, 0.05C), and then discharged to a discharge cut-off voltage at a constant rate (such as 1C) to complete the full charge and full discharge process of the battery cell. During the discharge, the nominal capacity C0 of the battery cell can be calculated according to the real-time current and discharge time by the ampere-hour integration method with the help of high-precision test equipment. It should be understood that the standard charge and discharge process exemplified above is not unique, but may vary depending on the battery model and product requirements.

[0054] In step S202, the battery cell is discharged from a fully charged state to a preset starting SOC. It is understandable that before executing step S202, the battery cell has been pre-charged, for example, through a standard charging process, so that it reaches a fully charged state. Specifically, the preset starting SOC can be achieved by controlling the discharge amount. Assuming that the nominal capacity of the battery cell is 100Ah through step S201, and the target starting SOC is 10%, the corresponding remaining power should be 10Ah. Then, the termination condition of the discharge process can be set by inputting a discharge amount of 90Ah into the high-precision test equipment.

[0055] In step S21, at a preset starting SOC, the ambient temperature of the battery cell is maintained at a predetermined temperature. In each test cycle, the ambient temperature is no longer actively changed to ensure the consistency of the test.

[0056] In step S21', after the ambient temperature of the battery cell is adjusted to a predetermined temperature, the battery cell is kept in a static state for a predetermined period of time. During this period, the battery is in a non-use state, and is neither actively discharged nor charged.

[0057] In step S22, the battery cell may be charged to a cut-off voltage using a fixed charge rate. The same charge rate may be used for each test cycle to study the effect of different rates on the degree of drift of the dynamic voltage-SOC correspondence relationship. In more complex applications, a combination of multiple charge rates may also be used in one test cycle.

[0058] In step S23, during the charging process of the battery cell, the dynamic voltage Vi and the charging capacity Ci of the battery cell are recorded in real time, and based on the charging capacity Ci, the starting SOC and the nominal capacity C0 of the battery cell, the test SOC value corresponding to each dynamic voltage point is calculated:

[0059] SOCi=SOC0+Ci / C0

[0060] Among them, SOCi is the test SOC value, SOC0 is the starting SOC value, Ci is the charging capacity, and C0 is the nominal capacity of the battery unit. The charging capacity Ci can be calculated by high-precision test equipment using the ampere-hour integration method.

[0061] In step S24, the operating conditions are changed and steps S21 to S23 are repeatedly performed to establish a dynamic voltage-SOC test matrix for different operating conditions. Different operating conditions can be set for each charging cycle, such as different starting SOC, ambient temperature and / or charging rate.

[0062] For each charging cycle, the point group consisting of dynamic voltage and SOC value obtained by step S23 is recorded in a table associated with the corresponding operating conditions, thereby forming a multi-dimensional test matrix. These matrices not only describe the correspondence between the dynamic voltage and SOC of the battery cell, but also reflect the operating conditions obtained by these correspondences, providing rich data support for battery performance analysis.

[0063] Figure 3 Schematically shows Figure 1 A flow chart of another method step of the method shown. Figure 3 In the embodiment shown, Figure 1 Step S3 of the method shown is shown to include sub-step S31 and step S32. It is assumed that the dynamic voltage-SOC test matrix of the battery cell has been established through the previous steps.

[0064] In step S31, for each dynamic voltage point, the test SOC value recorded in the established dynamic voltage-SOC test matrix is ​​compared with the reference SOC value in the reference correspondence, and it is checked whether the test SOC value is within a predefined error range of the reference SOC value.

[0065] The predefined error range can be presented in the form of a percentage error, for example, and is set to ±2%. If this value is too large, the SOC correction accuracy may decrease, and if it is too small, the applicable scope of the correction strategy may be excessively limited. Therefore, the reasonable size of the predefined error can be determined by combining the calculation robustness, the SOC correction accuracy and other factors through a pre-calibration process.

[0066] In step S32, the operating condition that enables the test SOC values ​​corresponding to the determined number of dynamic voltage points to fall within the predefined error range of the reference SOC value is determined as the SOC correction applicable condition. Figure 5 The dynamic voltage-SOC test matrix is ​​shown for illustration.

[0067] Exemplarily, the reference correspondence may be defined as:

[0068] 3.48V corresponds to 98% SOC;

[0069] 3.55V corresponds to 99% SOC;

[0070] 3.65V corresponds to 100% SOC.

[0071] Therefore, if the predefined error size is set to ±2%, then for a dynamic voltage of 3.48V, when the test SOC value is between 96% and 100% (i.e., within the ±2% range of 98% SOC), it will be considered "passed". Similarly, for dynamic voltages of 3.55V and 3.65V, the same determination method can be used.

[0072] exist Figure 5 In the test matrix shown, for example, the test results of "pass" and "fail" can be marked with no shading and shading respectively. Specifically:

[0073] exist Figure 5 The upper side shows the relationship between the dynamic voltage point of the battery cell and the test SOC value at different ambient temperatures (10°C, 15°C, 20°C, 25°C) and different charging rates (0.3C, 0.2C, 0.1C) when the starting SOC of the battery cell is 0%. It can be seen that at an ambient temperature of 10°C, regardless of whether the charging rate is 0.1C, 0.2C or 0.3C, all test results do not meet the predefined error range and are therefore marked as "failed". When the ambient temperature is 15°C, only at a charging rate of 0.1C, the test results meet the requirements and are marked as "passed". At ambient temperatures of 20°C and 25°C, only at charging rates of 0.2C and 0.1C, the test results meet the requirements and are marked as "passed".

[0074] exist Figure 5 The lower side also shows the correspondence between the dynamic voltage point of the battery cell and the test SOC value at different ambient temperatures (15°C and 20°C) and different starting SOCs (0% SOC, 20% SOC, 50% SOC and 80%) when charging at a charging rate of 0.3C. It can be seen from the test matrix that when the starting SOC is 0% and charged at 0.3C, the test results at all ambient temperatures (15°C and 20°C) fail. When the starting SOC is 20%, 50% or 80%, the test results of charging at a charging rate of 0.3C at temperatures of 15°C and 20°C all meet the conditions and are marked as "passed".

[0075] In one embodiment, it may be specified that if the test SOC values ​​corresponding to all three dynamic voltage points (3.65V, 3.55V, and 3.48V) are marked as "passed", the relevant operating conditions may be determined as SOC correction applicable conditions. Finally, the results of the test matrix may be summarized to obtain the following SOC correction applicable conditions:

[0076] The initial SOC is greater than or equal to 0%, the ambient temperature is greater than or equal to 20°C, and the charging rate is less than or equal to 0.2C;

[0077] The initial SOC is greater than or equal to 0%, the ambient temperature is greater than or equal to 15°C, and the charging rate is less than or equal to 0.1C;

[0078] The initial SOC is greater than or equal to 20%, the ambient temperature is greater than or equal to 15°C, and the charging rate is less than or equal to 0.3C.

[0079] It should be noted that although only three dynamic voltage points in the reference correspondence are shown in the above example, this is only for illustration purposes. In actual applications, more dynamic voltage data points can be obtained through experimental measurement, curve fitting or interpolation.

[0080] Figure 4 Schematically shows a flow chart of a method for correcting the SOC of a battery cell according to an exemplary embodiment of the present application. Figure 4 As shown, the method includes steps S410, S420, S430 and S440.

[0081] In step S410, the actual measured dynamic voltage and the actual measured SOC of the battery cell when the charging termination condition is reached under the actual operating conditions are obtained. This can be achieved, for example, with the help of a battery management system.

[0082] The charge termination condition is usually defined as: the voltage of any battery cell in the battery pack reaches the preset charge cut-off voltage. Since the cells in the battery pack may exhibit different charging characteristics due to manufacturing differences and aging, some cells may reach their cut-off voltage before other cells. To avoid overcharging, once any cell is detected to have reached the cut-off voltage, the charging process of the entire battery pack is usually terminated.

[0083] Therefore, at the time of charge termination, the measured dynamic voltage of the battery cell may be equal to the charge cut-off voltage, or may not have reached this voltage.

[0084] In step S420, check whether the actual operating conditions are in accordance with Figures 1 to 3 The SOC correction applicable conditions determined by the method.

[0085] As mentioned above, once these SOC correction applicable conditions are determined, they can be stored in the vehicle's battery management system (BMS) or in the cloud. In actual applications, these conditions can be directly accessed or retrieved remotely through the BMS, and then compared with the current actual operating conditions to confirm whether they match.

[0086] In step S430, when it is determined that the actual operating conditions are applicable conditions for SOC correction, the theoretical SOC of the battery cell can be obtained based on the measured dynamic voltage based on the reference correspondence, and the measured SOC of the battery cell can be corrected with the help of the theoretical SOC.

[0087] For example, the measured voltage of the battery cell is 3.48 V, and the measured SOC at this time is 100%, but the reference correspondence shows that the theoretical SOC at 3.48 V should be 98%. In this case, if it is determined that the actual operating conditions belong to the applicable conditions for SOC correction, the measured SOC can be updated using 98% of the theoretical SOC.

[0088] If it is determined in step S420 that the actual operating condition does not meet the SOC correction applicable condition, the dynamic voltage-SOC reference correspondence is not used to adjust the measured SOC in step S440. At this time, other correction measures can be taken, or a new reference correspondence that is compatible with the current operating condition can be sought.

[0089] FIG. 6A to FIG. 6E Schematic diagrams of the curves of the dynamic voltage Vi-SOC are schematically shown. In particular, these curves generally depict the situation that the dynamic voltage rises when the SOC increases from 80% (or 90%) to 100%. In the SOC range below 80%, the Vi-SOC curve is relatively flat (indicating that the voltage is not very sensitive to changes in SOC), which is not specifically shown for simplicity.

[0090] Fig. 6A The figure shows the effect of different ambient temperatures of 10°C, 15°C, 20°C, and 25°C on the curve drift at a starting SOC of 0% and a charge rate of 0.1C. It can be observed from the figure that as the ambient temperature decreases, the curve gradually shifts to the left. For example, at a dynamic voltage of 3.48V, if the ambient temperature is low (10°C), the corresponding SOC is only about 93%, while the expected SOC corresponding to this dynamic voltage on the reference curve is 98%. This shows that if the same reference curve is used for SOC correction at different temperatures, correction errors may occur.

[0091] FIG. 6B to FIG. 6C The Vi-SOC measured at two other charging rates, 0.2C and 0.3C, are shown respectively. FIG. 6A to FIG. 6C, we can get the influence of different charging rates of 0.1C, 0.2C and 0.3C on the dynamic voltage-SOC curve. FIG. 6A to FIG. 6C It can be observed that under fixed ambient temperature and starting SOC conditions, changes in charge rate will cause the curve to shift accordingly. In particular, at lower ambient temperatures (e.g., 10°C), this shift is more significant.

[0092] Fig.6D and Fig. 6E The influence of different starting SOC on the dynamic voltage-SOC curve drift at ambient temperatures of 15°C and 20°C is shown respectively. By observing these two curves, it can be found that the change of the starting SOC will cause the curve to shift in position. In particular, at lower ambient temperatures (such as 15°C), the curve drift caused by different starting SOCs is more significant, while at higher ambient temperatures (such as 20°C), this drift effect is not so obvious.

[0093] Figure 7 The structure block diagram of a device 700 for determining applicable conditions for SOC correction of a battery cell according to an exemplary embodiment of the present application is schematically shown.

[0094] like Figure 7 As shown, the device 700 includes a memory 710 and a processor 720, which can be coupled together via a bus. However, it should be understood that Figure 7 This is only an example and does not limit the scope of the present application. For example, in different application scenarios, the device 700 may also include an input interface and an output interface, which is not limited herein.

[0095] The memory 710 stores a computer program. When the computer program is executed by the processor 720, the processor 720 can execute the method for determining the applicable conditions for SOC correction of a battery cell according to an exemplary embodiment of the present application. The computer program instructions may 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.

[0096] The processor 720 may be a central processing unit, or other general-purpose processors, digital signal processors, application-specific integrated circuits, off-the-shelf programmable gate arrays, or other programmable logic devices.

[0097] The acquisition of reference correspondence, drift correspondence and determination of applicable conditions for SOC correction have been Figures 1 to 3 It should be noted that the features and advantages of the method described herein are also applicable to the device 700, and vice versa.

[0098] Figure 8 The structure block diagram of a device 800 for correcting the SOC of a battery cell according to an exemplary embodiment of the present application is schematically shown.

[0099] The device 800 may be implemented as a battery management system (BMS) of a vehicle or a component thereof, for example, and in practical applications may be connected to each battery cell of a power battery of the vehicle.

[0100] like Figure 8 As shown, the device 800 includes a memory 810 and a processor 820, which can be coupled together via a bus. However, it should be understood that Figure 8 This is only an example and does not limit the scope of the present application. For example, in different application scenarios, the device 800 may also include an input interface and an output interface, which is not limited herein.

[0101] The memory 810 stores a computer program. When the computer program is executed by the processor 820, the processor 820 can execute the method for determining the applicable conditions for SOC correction of a battery cell according to an exemplary embodiment of the present application. The computer program instructions may 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.

[0102] The processor 820 may be a central processing unit, or other general-purpose processors, digital signal processors, application-specific integrated circuits, off-the-shelf programmable gate arrays, or other programmable logic devices.

[0103] The acquisition of measured dynamic voltage and measured SOC, the inspection of applicable conditions for SOC correction, and the specific correction process of measured SOC have been Figure 4 It should be noted that the features and advantages of the method described herein are also applicable to the device 800, and vice versa.

[0104] It is understood that the methods of the various 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 used to execute the methods according to the various embodiments of the present application when running.

[0105] According to another embodiment of the present application, a computer program product is provided, such as a machine (e.g., computer) readable medium, such as a CD-ROM, which includes a computer program code, which, when executed, causes a computer or a processor to perform a method according to each embodiment of the present application. The machine readable medium is, for example, an optical storage medium or a solid-state medium supplied with other hardware or as part of other hardware.

[0106] Although the specific embodiments of the present application are described in detail herein, they are provided for the purpose of explanation only and should not be considered to limit the scope of the present application. Various substitutions, changes and modifications may be conceived without departing from the spirit and scope of the present application.

Claims

1. A method for determining an applicable condition for SOC correction of a battery cell, the method comprising the following steps: Step S1: obtaining a reference corresponding relationship between the dynamic voltage and SOC of the battery cell; Step S2: obtaining a drift correspondence between a dynamic voltage and SOC of a battery cell under different operating conditions, wherein the different operating conditions are different at least in terms of a starting SOC of the battery cell, an ambient temperature of the battery cell, and / or a charging rate; as well as Step S3: Determine an applicable SOC correction condition for performing SOC correction on the battery cell with the reference corresponding relationship according to the degree of deviation between the drift corresponding relationship and the reference corresponding relationship.

2. The method according to claim 1, wherein: The step S2 comprises: Step S21: maintaining the ambient temperature of the battery cell at a predetermined temperature under a preset starting SOC; Step S22: charging the battery cell to a cut-off voltage using a fixed charging rate; Step S23: During the charging process of the battery cell, the dynamic voltage and charging power of the battery cell are recorded in real time, and based on the charging power, the initial SOC and the nominal capacity of the battery cell, the test SOC value corresponding to each dynamic voltage point is calculated; and Step S24: changing the operating conditions and repeatedly executing steps S21 to S23 to establish a dynamic voltage-SOC test matrix for different operating conditions.

3. The method according to claim 2, wherein: The step S3 comprises: The following operating conditions are determined as the applicable conditions for SOC correction: the degree of deviation between the drift correspondence obtained under the operating conditions and the reference correspondence is less than a predetermined threshold, wherein: For each dynamic voltage point, comparing the test SOC value recorded in the established dynamic voltage-SOC test matrix with the reference SOC value in the reference correspondence, and checking whether the test SOC value is within a predefined error range of the reference SOC value, wherein the predefined error range is particularly set to ±2%; and An operating condition that enables the test SOC values ​​corresponding to a determined number of dynamic voltage points to all fall within a predefined error range of the reference SOC value is determined as an SOC correction applicable condition.

4. The method according to any one of claims 1 to 3, wherein: In step S3, only for the determined dynamic voltage interval, the deviation degree between the drift correspondence and the reference correspondence is calculated and the SOC correction applicable condition is determined according to the deviation degree. The determined dynamic voltage interval is particularly set to 3.48V to 3.65V.

5. The method according to any one of claims 1 to 4, wherein: The step S3 further includes: evaluating the influence of the change trend of the operating conditions on the degree of deviation, wherein as the initial SOC in the operating conditions increases, the charging rate decreases, and the ambient temperature increases, the degree of deviation between the drift correspondence relationship and the reference correspondence relationship decreases; In step S3, when the deviation is required to be less than or equal to 2%, the following operating conditions are determined as SOC correction applicable conditions: The initial SOC is greater than or equal to 0%, the ambient temperature is greater than or equal to 20°C, and the charging rate is less than or equal to 0.2C; The initial SOC is greater than or equal to 0%, the ambient temperature is greater than or equal to 15°C, and the charging rate is less than or equal to 0.1C; The initial SOC is greater than or equal to 20%, the ambient temperature is greater than or equal to 15°C, and the charging rate is less than or equal to 0.3C.

6. The method according to any one of claims 1 to 5, wherein: The step S2 further comprises: Step S201: performing a charge and discharge test on the battery cell through a standard charge and discharge process to determine the nominal capacity of the battery cell; Step S202: discharging the battery cell from a fully charged state to a preset starting SOC, wherein the discharging process is terminated by controlling the discharge amount of the battery cell, wherein the discharge amount is set according to the preset starting SOC; and / or Step S21 ′: after adjusting the ambient temperature of the battery cell to a predetermined temperature, keeping the battery cell in a stationary state for a predetermined period of time.

7. A method for correcting the SOC of a battery cell, the method comprising the following steps: Obtain the measured dynamic voltage and measured SOC of the battery cell when the charging termination condition is reached under actual operating conditions; checking whether the actual operating condition belongs to the SOC correction applicable condition determined by the method according to any one of claims 1 to 6; as well as When it is determined that the actual operating conditions belong to the applicable conditions for SOC correction, based on the reference correspondence between the dynamic voltage of the battery cell and the SOC, the theoretical SOC of the battery cell is obtained according to the measured dynamic voltage, and the measured SOC of the battery cell is corrected with the help of the theoretical SOC.

8. A device for determining an applicable condition for SOC correction of a battery cell, 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 6.

9. A device for correcting the SOC of a battery cell, 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 claim 7.

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 7.

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