Method, device and equipment for estimating SOC (State of Charge) of battery cell

Abstract

The invention is suitable for the field of electricity, and provides a cell SOC estimation method, device and equipment, and the cell SOC estimation method comprises the steps: obtaining the current state of a target cell; if the current state is the charging and discharging state, estimating dynamic SOC data of the target battery cell according to a preset ampere-hour integral algorithm; and if the current state is a non-working state, acquiring the duration of the non-working state, and when the duration of the non-working state reaches a preset duration threshold, calibrating the dynamic SOC data according to a preset open-circuit voltage algorithm to obtain target SOC data. According to the method, the problem of SOC deviation caused by the fact that self-discharge loss cannot be calculated in the ampere-hour integration method when the battery cell stands is effectively solved. The defect that the SOC cannot be accurately estimated due to the polarization effect under the dynamic working condition by an open-circuit voltage method is overcome. According to the method, high-precision estimation of the SOC of the battery cell under the full working condition is realized, the technical problem that the estimation accuracy of dynamic and static scenes is difficult to consider by a single method is solved, and more reliable SOC data support is provided for a BMS (Battery Management System).

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of electricity, and particularly relates to a method, device and equipment for estimating SOC of an electric core. BACKGROUND

[0002] In a battery management system (BMS), accurate estimation of SOC of an electric core is crucial for safe use and life guarantee of a battery.

[0003] Currently, there are two main methods for estimating SOC: the ampere-hour integration method is suitable for dynamic scenarios such as charging and discharging, and can track the change of SOC in real time, but cannot calculate the self-discharge loss when the electric core is at rest, and long-term use will cause deviation; the open-circuit voltage method is based on the correspondence between SOC and open-circuit voltage, and is suitable for static scenarios, but is affected by polarization effect under dynamic working conditions, and cannot be used for dynamic SOC estimation.

[0004] Therefore, a single method cannot achieve high-precision SOC estimation under all working conditions. SUMMARY

[0005] Embodiments of the application provide a method, device and equipment for estimating SOC of an electric core, which can solve the above problems.

[0006] In a first aspect, embodiments of the application provide a method for estimating SOC of an electric core, comprising:

[0007] obtaining a current state of a target electric core;

[0008] if the current state is a charging and discharging state, estimating dynamic SOC data of the target electric core according to a preset ampere-hour integration algorithm;

[0009] if the current state is a non-working state, obtaining a non-working state duration, and when the non-working state duration reaches a preset duration threshold, calibrating the dynamic SOC data according to a preset open-circuit voltage algorithm to obtain target SOC data; wherein the preset open-circuit voltage algorithm is based on a relationship curve between static SOC and open-circuit voltage.

[0010] Further, before the calibration of the dynamic SOC data according to the preset open-circuit voltage algorithm to obtain the target SOC data, the method comprises the steps of:

[0011] controlling the target electric core to perform gradient discharge to obtain the relationship curve between the static SOC and the open-circuit voltage.

[0012] Further, the control of the target electric core to perform gradient discharge to obtain the relationship curve between the static SOC and the open-circuit voltage comprises the steps of:

[0013] According to a preset SOC gradient, the target battery cell is controlled to be discharged at a preset rate, and after each gradient discharge is completed, a static duration is obtained;

[0014] If the static duration reaches a preset duration threshold, a current open circuit voltage is tested to obtain a correspondence between a current SOC and the current open circuit voltage;

[0015] Until the gradient discharge of the target battery cell is completed, a relationship curve between the static SOC and the open circuit voltage is obtained.

[0016] Further, the preset SOC gradient is divided according to a 5% gradient interval, the preset duration threshold is 48 hours, and the preset speed is 0.2C, where C is a rated capacity of the target battery cell.

[0017] Further, before the target battery cell is controlled to be discharged at a gradient to obtain the relationship curve between the static SOC and the open circuit voltage, the method comprises the following steps:

[0018] Based on preset charging and discharging parameters, the target battery cell is controlled to be completely discharged and completely charged.

[0019] Further, based on the preset charging and discharging parameters, the target battery cell is controlled to be completely discharged and completely charged, comprising the following steps:

[0020] At a preset temperature, the target battery cell is controlled to be completely discharged at a preset rate, and when the complete discharge is completed, the target battery cell is controlled to be completely charged at a preset rate;

[0021] When the complete charging is completed, a static duration is obtained.

[0022] If the static duration reaches a preset duration threshold, a full-charge open circuit voltage and a capacity of the target battery cell are obtained.

[0023] Further, before the current state of the target battery cell is obtained, the method comprises the following steps:

[0024] The charging and discharging cutoff voltage, the protection voltage, the ampere-hour integral algorithm and the open circuit voltage algorithm are obtained.

[0025] The charging and discharging cutoff voltage, the protection voltage, the ampere-hour integral algorithm and the open circuit voltage algorithm are pre-written into an integrated circuit control program of a battery management system.

[0026] In a second aspect, an embodiment of the present application provides a battery cell SOC estimation device, comprising:

[0027] A first obtaining unit is configured to obtain a current state of a target battery cell.

[0028] a first processing unit configured to, if the current state is a charging and discharging state, estimate dynamic SOC data of the target battery cell according to a preset ampere-hour integration algorithm;

[0029] a second processing unit configured to, if the current state is a non-working state, obtain a non-working state duration, and when the non-working state duration reaches a preset duration threshold, calibrate the dynamic SOC data to obtain target SOC data according to a preset open-circuit voltage algorithm based on a static SOC and open-circuit voltage relationship curve.

[0030] Further, the battery cell SOC estimation device further comprises:

[0031] a third processing unit configured to control the target battery cell to perform gradient discharging to obtain the static SOC and open-circuit voltage relationship curve.

[0032] Further, the third processing unit is specifically configured to:

[0033] control the target battery cell to perform gradient discharging at a preset speed according to a preset SOC gradient, and obtain a static duration after each gradient discharging is completed;

[0034] if the static duration reaches a preset duration threshold, test a current open-circuit voltage to obtain a corresponding relationship between a current SOC and the current open-circuit voltage;

[0035] until the gradient discharging of the target battery cell is completed, the static SOC and open-circuit voltage relationship curve is obtained.

[0036] Further, the preset SOC gradient is divided according to a 5% gradient interval, the preset duration threshold is 48 hours, and the preset speed is 0.2C, where C is a rated capacity of the target battery cell.

[0037] Further, the battery cell SOC estimation device further comprises:

[0038] a fourth processing unit configured to control the target battery cell to perform complete discharging and complete charging cycles based on preset charging and discharging parameters.

[0039] Further, the fourth processing unit is specifically configured to:

[0040] control the target battery cell to perform complete discharging at a preset speed at a preset temperature, and then control the target battery cell to perform complete charging at a preset speed when the complete discharging is completed;

[0041] obtain a static duration when the complete charging is completed.

[0042] If the static duration reaches a preset duration threshold, a full charge open circuit voltage and a capacity of the target battery cell are acquired.

[0043] Further, the battery cell SOC estimation device further comprises:

[0044] The second acquisition unit is configured to acquire a charge / discharge cutoff voltage, a protection voltage, an ampere-hour integral algorithm, and an open circuit voltage algorithm.

[0045] The fifth processing unit is configured to prewrite the charge / discharge cutoff voltage, the protection voltage, the ampere-hour integral algorithm, and the open circuit voltage algorithm into an integrated circuit control program of a battery management system.

[0046] In a third aspect, an embodiment of the present application provides a battery cell SOC estimation device, which comprises a memory, a processor, and a computer program stored in the memory and executable on the processor, and the processor implements the method of the first aspect when executing the computer program.

[0047] In a fourth aspect, an embodiment of the present application provides a computer readable storage medium, which stores a computer program, and the computer program is executable on a processor to implement the method of the first aspect.

[0048] In the embodiment of the present application, a current state of a target battery cell is acquired; if the current state is a charge / discharge state, a dynamic SOC data of the target battery cell is estimated according to a preset ampere-hour integral algorithm; if the current state is a non-working state, a non-working state duration is acquired, and when the non-working state duration reaches a preset duration threshold, the dynamic SOC data is calibrated according to a preset open circuit voltage algorithm to obtain target SOC data. The SOC deviation problem caused by the inability to calculate self-discharge loss of the ampere-hour integral method when the battery cell is static is effectively solved. By calibrating the dynamic SOC data using the open circuit voltage method after the non-working state reaches the preset duration, the cumulative error caused by self-discharge can be corrected in time, and the accuracy of SOC estimation after static is ensured. The defect that the open circuit voltage method cannot accurately estimate the SOC under dynamic working conditions due to polarization effect is overcome. By using the ampere-hour integral method only under dynamic states such as charging and discharging, the real-time tracking advantage of dynamic power change is fully utilized, the interference of polarization voltage on the estimation result is avoided, and the SOC estimation accuracy under dynamic scenes is ensured. The high-precision estimation of the SOC of the battery cell under all working conditions is realized, the technical problem that a single method cannot simultaneously ensure the estimation accuracy of dynamic and static scenes is solved, and more reliable SOC data support is provided for the BMS. BRIEF DESCRIPTION OF DRAWINGS

[0049] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments or prior art description will be briefly introduced as follows. Obviously, the drawings in the following description only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor.

[0050] Figure 1 is a schematic flow chart of a method for estimating SOC of an electric core provided by the first embodiment of the present application;

[0051] Figure 2 is a schematic flow chart of S104-S105 in the method for estimating SOC of an electric core provided by the first embodiment of the present application;

[0052] Figure 3 is a schematic flow chart of S106 in the method for estimating SOC of an electric core provided by the first embodiment of the present application;

[0053] Figure 4 is a schematic flow chart of S107 in the method for estimating SOC of an electric core provided by the first embodiment of the present application;

[0054] Figure 5 is a schematic diagram of an apparatus for estimating SOC of an electric core provided by the second embodiment of the present application;

[0055] Figure 6 is a schematic diagram of an apparatus for estimating SOC of an electric core provided by the third embodiment of the present application. DETAILED DESCRIPTION

[0056] In the following description, specific details are set forth in order to provide a thorough understanding of the embodiments of the present application. However, persons skilled in the art will understand that the present application can be practiced without these specific details. In other instances, well-known systems, structures, circuits, and methods have not been described in detail in order to not unnecessarily obscure the description of the present application.

[0057] It should be understood that, when used in the specification and the appended claims of the present application, the term "comprising" indicates the presence of the described features, integers, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0058] It should also be understood that the term "and / or" used in the specification and the appended claims of the present application means any combination of one or more of the associated listed items and all possible combinations, and includes these combinations.

[0059] As used in the specification and the appended claims, the term "if' can be interpreted as meaning "when" or "upon" or "in response to determining" or "in response to detecting" depending on the context. Similarly, the phrase "if it is determined" or "if [the described condition or event] is detected" can be interpreted as meaning "upon determining" or "in response to determining" or "upon detecting [the described condition or event]" or "in response to detecting [the described condition or event]" depending on the context.

[0060] In addition, in the description of the present application and the appended claims, the terms "first", "second", "third", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0061] In the present application, the reference "one embodiment" or "some embodiments" and the like means that the specific features, structures or characteristics described in connection with the embodiment are included in one or more embodiments of the present application. Therefore, the statements "in one embodiment", "in some embodiments", "in other some embodiments", "in further some embodiments" and the like appearing in different places in the specification are not necessarily all referring to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized. The terms "include", "contain", "have" and their variants mean "include but not limited to", unless otherwise specifically emphasized.

[0062] Please refer to Figure 1 , Figure 1 is a schematic flowchart of an electric core SOC estimation method provided by the first embodiment of the present application. In the present embodiment, the execution subject of the electric core SOC estimation method is a device with an electric core SOC estimation function, such as a desktop computer, a server, etc. As shown in the electric core SOC estimation method can include: Figure 1

[0063] S101: Obtain the current state of the target electric core.

[0064] In the present embodiment, SOC (State of Charge) refers to the state of charge of the battery, which can also be understood as "the percentage of the current remaining capacity of the battery". It is like the power display in the mobile phone, which lets us know how much energy the battery can use.

[0065] The battery management system BMS (Battery Management System) is the link between the battery and the user. The main object of BMS is secondary battery, the purpose is to improve the utilization rate of the battery, prevent the battery from overcharging and overdischarging, prolong the service life of the battery, monitor the state of the battery. ​

[0066] The device obtains the current state of the target battery cell, which can be determined by the real-time data of the current sensor, voltage sampling module and battery management system (BMS), to determine whether the battery cell is in a dynamic charging and discharging working condition (such as the absolute value of the current > 5% of the rated capacity) or a completely static non-working state.

[0067] In an embodiment, before S101, S104-S105 can also be included, as shown in Figure 2 S104-S105 are specifically as follows:

[0068] S104: Obtain the charging and discharging cutoff voltage, protection voltage, ampere-hour integral algorithm and open-circuit voltage algorithm.

[0069] In this embodiment, the charging and discharging cutoff voltage refers to the highest charging voltage (such as 4.2V) and the lowest discharging voltage (such as 2.75V) allowed by the battery cell, which is a threshold for determining whether the battery cell is fully charged or empty, and directly affects the upper and lower limit reference of the power calculation in the ampere-hour integral method;

[0070] The protection voltage is usually slightly higher than the cutoff voltage (such as a charging protection voltage of 4.3V) or slightly lower than the cutoff voltage (such as a discharging protection voltage of 2.7V), which is used to trigger the safety protection mechanism of the BMS to prevent the battery cell from being damaged due to overcharging or overdischarging, and is a safety boundary parameter in the SOC estimation process;

[0071] The ampere-hour integral algorithm is the logic of implementing current integral operation (such as an algorithm program containing details such as initial SOC calibration, current sampling frequency, efficiency coefficient correction), which is the core calculation rule of dynamic SOC estimation;

[0072] The open-circuit voltage algorithm includes voltage lookup table and interpolation calculation based on the SOC-OCV relationship curve, which is the specific calculation rule for converting open-circuit voltage to SOC value in the static calibration stage.

[0073] The acquisition of these parameters and algorithms needs to be combined with the specification parameters of the battery cell (such as nominal voltage, capacity), electrochemical characteristics and safety standards to ensure that they match the characteristics of the target battery cell.

[0074] S105: Pre-write the charging and discharging cutoff voltage, the protection voltage, the ampere-hour integral algorithm and the open-circuit voltage algorithm into the integrated circuit control program of the battery management system.

[0075] By pre-writing the parameters such as charging and discharging cutoff voltage and protection voltage obtained in S104, as well as the logic code of the ampere-hour integral algorithm and the open-circuit voltage algorithm, into the integrated circuit control program (such as the firmware program of the MCU) of the battery management system (BMS), the BMS hardware is enabled to perform SOC estimation.

[0076] S102: If the current state is a charging and discharging state, the dynamic SOC data of the target battery cell is estimated according to a preset ampere-hour integration algorithm.

[0077] When it is determined that the battery cell is in a charging and discharging state, the ampere-hour integration method is used for SOC estimation.

[0078] The ampere-hour integration method can accurately track the change of power in a dynamic process by real-time integration of the charging and discharging current, adapt to the scene of rapid current fluctuation, and ensure the real-time and continuity of SOC estimation under dynamic conditions.

[0079] The device is pre-set with an ampere-hour integration algorithm, and the dynamic SOC data of the target battery cell is estimated according to the preset ampere-hour integration algorithm.

[0080] The ampere-hour integration formula can be as follows:

[0081]

[0082] Wherein, SOC0 is the initial state of charge, I is the battery charging and discharging current, t is the time, and C is the total capacity of the battery. The capacity change of the battery in this period of time is obtained by integrating the current and time, and the percentage of capacity change is obtained by dividing the total capacity. The current SOC value is obtained by subtracting the percentage of capacity change from the initial SOC value.

[0083] In the ampere-hour integration method, the accuracy of the current I greatly affects the SOC calculation, so a high-precision current sensor is selected as much as possible, and the current sampling period is set as short as possible. The total capacity C of the battery is affected by battery aging and battery temperature. The battery capacity at different temperatures can be tested to obtain a more accurate current total capacity of the battery.

[0084] In this embodiment, the dynamic SOC data of the target battery cell is based on the real-time current change, which conforms to the state characteristics of the battery cell in the charging and discharging process.

[0085] S103: If the current state is a non-working state, the non-working state duration is obtained, and when the non-working state duration reaches a preset duration threshold, the dynamic SOC data is calibrated according to a preset open circuit voltage algorithm to obtain target SOC data; wherein the preset open circuit voltage algorithm is based on a relationship curve between static SOC and open circuit voltage.

[0086] When the battery cell is in a non-working state (such as static, no charging and discharging current), the duration of the non-working state is monitored first to obtain the non-working state duration. This process needs to ensure that the battery cell is completely separated from the charging and discharging cycle to avoid any current fluctuation interference to the state judgment.

[0087] A preset duration threshold is set in the device to ensure that the battery is fully rested, so that the polarization effect is basically eliminated (the polarization voltage decays to a negligible level), and at this time the open-circuit voltage of the battery can truly reflect its SOC state.

[0088] When the non-working state duration reaches the preset duration threshold, the dynamic SOC data obtained by the ampere-hour integration method is calibrated using the open-circuit voltage algorithm to obtain target SOC data.

[0089] Specifically, the current open-circuit voltage value of the battery is collected, and the static SOC reference value of the battery at this time is inversely deduced through a preset SOC-OCV relationship curve (which is a one-to-one correspondence relationship between the battery in a completely static state and the experimental calibration, such as OCV being 3.8V corresponding to SOC being 80%).

[0090] The static SOC reference value is compared with the dynamic SOC data output by the ampere-hour integration method at the last moment before resting to calculate the deviation value (such as dynamic SOC showing 75%, and OCV corresponding SOC being 70%, with a deviation of 5%). Subsequently, the dynamic SOC data is corrected based on the static SOC reference value (the original dynamic SOC data is uniformly reduced by 5% deviation), so that the calibrated target SOC data not only inherits the continuity of dynamic tracking, but also corrects the cumulative error caused by self-discharge.

[0091] The calibrated target SOC data will be used as a new reference value for the ampere-hour integration method calculation when the battery reenters the charging and discharging state, ensuring the accuracy of the starting point of dynamic estimation and avoiding continuous accumulation of deviation.

[0092] The ampere-hour integration method is corrected for the SOC deviation caused by self-discharge during the resting phase, and the target SOC data that takes into account the dynamic tracking accuracy and static calibration correction is ultimately obtained, realizing high-precision estimation under all working conditions.

[0093] In one embodiment, before S103, S106 can also be included: controlling the target battery to perform gradient discharge to obtain the relationship curve between the static SOC and the open-circuit voltage.

[0094] In this embodiment, the accurate correspondence between the SOC and the open-circuit voltage (OCV) of the battery in the static state is established in advance. Since the SOC-OCV characteristics of different batteries (even the same battery at different life cycles) may differ, the individualized curve obtained through gradient discharge experiments can ensure that the calibration result based on the open-circuit voltage method is more accurate, and avoid introducing additional errors due to the use of a general curve.

[0095] Specifically, a standard battery cell of the same model and batch as the target battery cell (or the target battery cell itself in the initial state) can be selected to ensure that it is in a healthy state and fully charged (SOC = 100%). The battery cell is controlled to perform gradient discharge at a preset small current (to avoid the polarization effect caused by large current discharge), and each time the discharge reaches a preset SOC gradient value (for example, a decrease of 5% SOC), the discharge is stopped and the battery cell is allowed to rest for a long enough time (usually 1-2 hours) until the internal polarization of the battery cell is completely eliminated and the voltage is stable. At the end of the rest corresponding to each SOC gradient, the stable open-circuit voltage value of the battery cell at this time is recorded to form a one-to-one corresponding data point of "SOC value-OCV value" (for example, SOC = 100% corresponds to OCV = 4.2V, SOC = 95% corresponds to OCV = 4.15V, etc.). All the collected data points are fitted to generate a continuous SOC-OCV relationship curve. The curve reflects the inherent law of the remaining capacity and the open-circuit voltage of the battery cell under completely static and non-polarization interference conditions.

[0096] In an implementation, to provide a high-precision reference for subsequent calibration, S106 can include S1061-S1063, as shown in Figure 3 S1061-S1063 are specifically as follows:

[0097] S1061: According to the preset SOC gradient, control the target battery cell to perform gradient discharge at a preset rate, and after each gradient discharge is completed, the resting time is obtained.

[0098] The SOC interval is divided according to the preset SOC gradient to ensure that the data points are uniformly distributed and cover the full SOC range. The target battery cell is controlled to perform gradient discharge at a small current rate, which can minimize the polarization effect during discharge and avoid interference with subsequent voltage measurement. After each gradient discharge is completed, the discharge is immediately stopped and the resting time of the battery cell is recorded to prepare for subsequent voltage stability monitoring.

[0099] S1062: If the resting time reaches a preset time threshold, test the current open-circuit voltage to obtain the corresponding relationship between the current SOC and the current open-circuit voltage.

[0100] When the resting time after a gradient discharge reaches the preset 48-hour threshold, it means that the internal electrochemical polarization and concentration polarization of the battery cell have been completely eliminated, and the voltage measured at this time is the pure open-circuit voltage (OCV), which can truly reflect the current SOC state. At this time, the SOC value (such as 95%) and the corresponding OCV value (such as 4.15V) in this state are recorded to form a set of accurate "SOC-OCV" corresponding data. The 48-hour threshold is set to ensure that the polarization effect of different types of battery cells (especially high-capacity or aged battery cells) can be completely attenuated, and the accuracy of the voltage data is guaranteed.

[0101] In an embodiment, the preset SOC gradient is divided according to a 5% gradient interval (for example, 100%→95%→90%→…→0%), the preset time threshold is 48 hours, and the preset speed is 0.2C, where C is the rated capacity of the target battery cell, for example, 2A for a 10Ah battery cell.

[0102] S1063: Until the gradient discharge of the target battery cell is completed, the static SOC-OCV relationship curve is obtained.

[0103] The operations of S1061-S1062 are repeated until the battery cell is discharged from 100% SOC to 0% SOC, and a plurality of sets of “SOC-OCV” data points covering the entire interval (for example, 20 sets, corresponding to 20 intervals of 5% gradient) are obtained. Finally, the discrete points are connected into a continuous curve by a data fitting algorithm (for example, polynomial fitting), which is the static SOC-OCV relationship curve. This curve completely reflects the inherent mapping rule of the remaining capacity and open circuit voltage of the target battery cell in the static state without polarization interference, ensuring the calibration accuracy.

[0104] In an embodiment, in order to restore the battery cell to a stable and consistent reference state through a standardized charge-discharge cycle, S107 can be further included before S106: based on preset charge-discharge parameters, the target battery cell is controlled to perform a full discharge-full charge cycle.

[0105] The preset charge-discharge parameters can include charge-discharge rates, cut-off voltages, etc., for example, charging at a rate of 0.5C to an upper limit voltage, and after standing, discharging at a rate of 0.5C to a lower limit voltage.

[0106] Specifically, the battery cell is discharged to its cut-off voltage (for example, 2.75V), ensuring that the remaining capacity inside the battery cell approaches 0 and eliminating the influence of residual charge; after the discharge is completed, the battery cell is fully charged to the upper limit voltage (for example, 4.2V) according to the standard process, so that the active material is fully activated and the chemical state is restored to be uniform.

[0107] S107 performs a “zero calibration” for the battery cell through a standardized charge-discharge cycle, ensuring that the SOC-OCV relationship curve constructed in S106 can truly reflect the inherent characteristics of the battery cell, avoiding distortion of the curve due to inconsistent initial states, and further improving the accuracy of subsequent SOC estimation and calibration.

[0108] In an embodiment, S107 can include S1071-S1073, as shown in FIG. 7. Figure 4 S1071-S1073 are specifically as follows:

[0109] S1071: Control the target battery to be fully discharged at a preset rate at a preset temperature, and then control the target battery to be fully charged at a preset rate when the fully discharging ends.

[0110] The standard working temperature of the battery (e.g., 25°C) can be selected as the preset temperature, because the temperature significantly affects the electrochemical characteristics of the battery, and a constant temperature can ensure the consistency of the charging and discharging process and avoid the capacity and voltage characteristic deviations caused by temperature fluctuations.

[0111] First, the battery is discharged to a cut-off voltage (e.g., 2.75V) at a preset rate (e.g., 0.5C), ensuring that the remaining power in the battery is zero; then immediately charged to a full cut-off voltage (e.g., 4.2V) at the same rate, so that the active material of the battery is fully reacted and restored to a unified full charge state.

[0112] S1072: When the fully charging ends, obtain the static duration.

[0113] After the fully charging ends, there may still be slight polarization in the battery, and the voltage at this time is not the true full charge open circuit voltage. Therefore, the charging and discharging operation needs to be stopped, and the static duration of the battery is started to be monitored.

[0114] S1073: If the static duration reaches a preset duration threshold, obtain the full charge open circuit voltage and capacity of the target battery.

[0115] When the static duration reaches a preset threshold (e.g., 2 hours, ensuring that the polarization is completely eliminated), the full charge open circuit voltage and capacity of the target battery are collected.

[0116] The voltage measured at this time is the true open circuit voltage (e.g., 4.2V) of the battery in the full charge state (SOC = 100%), which is the full charge open circuit voltage, serving as the starting point reference of the SOC-OCV curve.

[0117] By recording the total amount of electricity input during this fully charging process, the actual capacity of the battery (which may differ from the nominal capacity, especially for aged batteries) can be calibrated, providing an accurate capacity reference for the current integration calculation in the subsequent ampere-hour integration method.

[0118] In this embodiment, through temperature control, complete charging and discharging cycle and sufficient static state, the battery is ensured to be in a stable full charge reference state, and accurate full charge OCV and actual capacity parameters are obtained, which not only provides a reliable starting point for the gradient discharge experiment of S106, but also further reduces the system error.

[0119] In this embodiment, the ampere-hour integration method is used to guarantee real-time tracking ability in dynamic scenarios, and the open-circuit voltage method is used for calibration in static scenarios. The advantages of the two methods in their respective applicable scenarios are exerted, and the defects of the ampere-hour integration method that cannot handle self-discharge deviation and the open-circuit voltage method that is disturbed by dynamic polarization are overcome, so that high-precision SOC estimation of the battery cell in all working conditions such as charging and discharging and static is realized. The SOC deviation problem caused by the inability to calculate self-discharge loss when the battery cell is static is effectively solved. By calibrating the dynamic SOC data using the open-circuit voltage method after the non-working state reaches a preset time length, the cumulative error caused by self-discharge can be corrected in time to ensure the accuracy of the SOC estimation after static. The defect that the open-circuit voltage method cannot accurately estimate the SOC in dynamic working conditions due to polarization effect is overcome. By using the ampere-hour integration method only in dynamic states such as charging and discharging, the real-time tracking of dynamic power changes is fully exerted, the interference of polarization voltage on the estimation result is avoided, and the SOC estimation accuracy in dynamic scenarios is ensured. High-precision estimation of the SOC of the battery cell in all working conditions is realized, and the technical problem that a single method cannot simultaneously ensure the estimation accuracy in dynamic and static scenarios is solved, providing more reliable SOC data support for the BMS.

[0120] It should be understood that the size of the serial number of each step in the above embodiment does not mean the order of execution, and the execution order of each process should be determined according to its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0121] Please refer to Figure 5 , Figure 5 is a schematic diagram of the battery cell SOC estimation device provided by the second embodiment of the present application. Each unit included is used to execute Figures 1 to 4 each step in the corresponding embodiment. For details, please refer to Figures 1 to 4 the related description in the corresponding embodiment. For the sake of illustration, only the parts related to the present embodiment are shown. Please refer to Figure 5 , the battery cell SOC estimation device 5 includes:

[0122] The first acquisition unit 51 is configured to acquire the current state of the target battery cell.

[0123] The first processing unit 52 is configured to, if the current state is a charging and discharging state, estimate the dynamic SOC data of the target battery cell according to a preset ampere-hour integration algorithm.

[0124] The second processing unit 53 is configured to, if the current state is a non-working state, acquire the non-working state time length, and when the non-working state time length reaches a preset time threshold, calibrate the dynamic SOC data according to a preset open-circuit voltage algorithm to obtain target SOC data. The preset open-circuit voltage algorithm is based on the relationship curve between static SOC and open-circuit voltage.

[0125] Further, the battery cell SOC estimation device 5 further comprises:

[0126] a third processing unit, configured to control the target battery cell to perform gradient discharge to obtain the static SOC and open circuit voltage relationship curve.

[0127] Further, the third processing unit is specifically configured to:

[0128] control the target battery cell to perform gradient discharge at a preset speed according to a preset SOC gradient, and obtain a static duration after each gradient discharge is completed;

[0129] if the static duration reaches a preset duration threshold, test a current open circuit voltage to obtain a corresponding relationship between a current SOC and the current open circuit voltage;

[0130] until the gradient discharge of the target battery cell is completed, the static SOC and open circuit voltage relationship curve is obtained.

[0131] Further, the preset SOC gradient is divided according to a 5% gradient interval, the preset duration threshold is 48 hours, and the preset speed is 0.2C, wherein C is a rated capacity of the target battery cell.

[0132] Further, the battery cell SOC estimation device 5 further comprises:

[0133] a fourth processing unit, configured to control the target battery cell to perform complete discharge-complete charge cycle based on preset charge and discharge parameters.

[0134] Further, the fourth processing unit is specifically configured to:

[0135] control the target battery cell to perform complete discharge at a preset speed at a preset temperature, and then control the target battery cell to perform complete charge at a preset speed when the complete discharge is completed;

[0136] obtain a static duration when the complete charge is completed;

[0137] if the static duration reaches a preset duration threshold, obtain a full-charge open circuit voltage and a capacity of the target battery cell.

[0138] Further, the battery cell SOC estimation device 5 further comprises:

[0139] a second obtaining unit, configured to obtain charge and discharge cutoff voltage, protection voltage, ampere-hour integral algorithm and open circuit voltage algorithm;

[0140] The fifth processing unit is used to pre-write the charge / discharge cutoff voltage, the protection voltage, the ampere-hour integration algorithm, and the open-circuit voltage algorithm into the integrated circuit control program of the battery management system.

[0141] Figure 6 This is a schematic diagram of a cell SOC estimation device provided in the third embodiment of this application. Figure 6 As shown, the cell SOC estimation device 6 in this embodiment includes: a processor 60, a memory 61, and a computer program 62 stored in the memory 61 and executable on the processor 60, such as a cell SOC estimation program. When the processor 60 executes the computer program 62, it implements the steps in the various cell SOC estimation method embodiments described above, for example... Figure 1 Steps 101 to 103 are shown. Alternatively, when the processor 60 executes the computer program 62, it implements the functions of each module / unit in the above-described device embodiments, for example... Figure 5 The functions of modules 51 to 53 are shown.

[0142] For example, the computer program 62 can be divided into one or more modules / units, which are stored in the memory 61 and executed by the processor 60 to complete this application. The one or more modules / units can be a series of computer program instruction segments capable of performing specific functions, which describe the execution process of the computer program 62 in the cell SOC estimation device 6. For example, the computer program 62 can be divided into a first acquisition unit, a first processing unit, and a second processing unit, with the specific functions of each unit as follows:

[0143] The first acquisition unit is used to acquire the current state of the target battery cell;

[0144] The first processing unit is used to estimate the dynamic SOC data of the target cell according to a preset ampere-hour integration algorithm if the current state is a charging / discharging state.

[0145] The second processing unit is used to obtain the duration of the non-working state if the current state is a non-working state, and to calibrate the dynamic SOC data according to a preset open-circuit voltage algorithm when the duration of the non-working state reaches a preset duration threshold, so as to obtain the target SOC data; wherein the preset open-circuit voltage algorithm is based on the static relationship curve between SOC and open-circuit voltage.

[0146] The device for estimating the cell's state of charge (SOC) may include, but is not limited to, a processor 60 and a memory 61. Those skilled in the art will understand that... Figure 6The above-mentioned device / element is only an example of the battery SOC estimation device 6, and does not constitute a limitation on the battery SOC estimation device 6, and can include more or fewer components than those shown, or combine certain components, or different components, for example, the battery SOC estimation device can also include an input / output device, a network access device, a bus, etc.

[0147] The processor 60 can be a central processing unit (CPU), and can also be other general-purpose processors, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field-programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic device, discrete hardware component, etc. The general-purpose processor can be a microprocessor or the processor can also be any conventional processor.

[0148] The memory 61 can be an internal storage unit of the battery SOC estimation device 6, such as a hard disk or a memory of the battery SOC estimation device 6. The memory 61 can also be an external storage device of the battery SOC estimation device 6, such as a plug-in hard disk, a smart media card (SMC), a secure digital (SD) card, a flash card, etc. provided on the battery SOC estimation device 6. Further, the battery SOC estimation device 6 can include both the internal storage unit and the external storage device of the battery SOC estimation device 6. The memory 61 is used to store the computer program and other programs and data required by the battery SOC estimation device. The memory 61 can also be used to temporarily store data that has been output or will be output.

[0149] It should be noted that the information interaction, execution process, etc. between the above-mentioned devices / elements, since based on the same concept as the method embodiments of the present application, the specific functions and the technical effects brought by them can be referred to the method embodiment part, and will not be repeated here.

[0150] The present application also provides a network device, comprising at least one processor, a memory, and a computer program stored in the memory and executable on the at least one processor, wherein the processor implements the steps of any of the above-mentioned method embodiments when executing the computer program.

[0151] The embodiment of the present application further provides a computer readable storage medium, which stores a computer program. The computer program is executed by a processor to implement the steps in the above-mentioned various method embodiments.

[0152] The embodiment of the present application provides a computer program product. When the computer program product is run on a mobile terminal, the mobile terminal is caused to execute the steps in the above-mentioned various method embodiments.

[0153] The integrated unit, if realized in the form of a software function unit and sold or used as an independent product, can be stored in a computer readable storage medium. Based on such understanding, the present application can implement all or part of the processes in the above-mentioned embodiments by a computer program to instruct related hardware to complete, and the computer program can be stored in a computer readable storage medium. The computer program is executed by a processor to implement the steps in the above-mentioned various method embodiments. The computer program includes computer program code, which can be in the form of source code, object code, executable files or some intermediate forms. The computer readable medium at least includes any entity or device capable of carrying the computer program code to the photographing device / terminal equipment, recording medium, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signal, telecommunication signal and software distribution medium. For example, U disk, mobile hard disk, magnetic disk or optical disk, etc. In some jurisdictions, according to legislation and patent practice, the computer readable medium can not be an electrical carrier signal and a telecommunication signal.

[0154] In the above-mentioned embodiments, the description of each embodiment has its own focus. The parts not described or recorded in detail in a certain embodiment can be referred to the relevant description of other embodiments.

[0155] Those skilled in the art can realize that the units and algorithm steps of the examples described in combination with the embodiments disclosed herein can be realized by electronic hardware or a combination of computer software and electronic hardware. Whether the functions are realized in hardware or software depends on the specific application and design constraints of the technical solution. The skilled person can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of the present application.

[0156] In the embodiments provided by the present application, it should be understood that the disclosed apparatus / network device and method can be implemented in other manners. For example, the embodiments of the apparatus / network device described above are merely illustrative. For example, the division of the modules or units is merely logical function division, and there can be another division manner in actual implementation. For example, a plurality of units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the displayed or discussed mutual couplings or direct couplings or communication connections between the units can be indirect couplings or communication connections through some interfaces, devices or units, and can be electrical, mechanical or in other forms.

[0157] The units described as separate components can or can not be physically separate, and the components shown as units can or can not be physical units, i.e., can be located in one place, or can be distributed on a plurality of network units. Part or all of the units can be selected according to actual needs to achieve the purpose of the embodiments.

[0158] The above-described embodiments are merely used to illustrate the technical solutions of the present application, but not limit the present application; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: the technical solutions recorded in the foregoing embodiments can still be modified, or some technical features can be replaced by equivalent replacements; and these modifications or replacements do not make the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should be included in the protection scope of the present application.

Claims

1. A method of estimating SOC of a battery cell, characterized by, The method comprises the steps of: obtaining a current state of a target battery cell; if the current state is a charging and discharging state, estimating dynamic SOC data of the target battery cell according to a preset ampere-hour integration algorithm; if the current state is a non-working state, obtaining a non-working state duration, and when the non-working state duration reaches a preset duration threshold, calibrating the dynamic SOC data according to a preset open-circuit voltage algorithm to obtain target SOC data; wherein the preset open-circuit voltage algorithm is based on a relationship curve between a static SOC and an open-circuit voltage.

2. The method of estimating SOC of a battery cell according to claim 1, wherein, Before the calibration of the dynamic SOC data according to the preset open-circuit voltage algorithm to obtain the target SOC data, the method comprises the step of: controlling the target battery cell to perform gradient discharging to obtain the relationship curve between the static SOC and the open-circuit voltage.

3. The method of claim 2, wherein, The control of the target battery cell to perform gradient discharging to obtain the relationship curve between the static SOC and the open-circuit voltage comprises the steps of: controlling the target battery cell to perform gradient discharging at a preset speed according to a preset SOC gradient, and obtaining a static duration after each gradient discharging is completed; if the static duration reaches a preset duration threshold, testing a current open-circuit voltage to obtain a corresponding relationship between a current SOC and the current open-circuit voltage; until the gradient discharging of the target battery cell is completed, the relationship curve between the static SOC and the open-circuit voltage is obtained.

4. The method of estimating SOC of a battery cell according to claim 3, wherein, The preset SOC gradient is divided according to a 5% gradient interval, the preset duration threshold is 48 hours, and the preset speed is 0.2C, wherein C is a rated capacity of the target battery cell.

5. The method of estimating SOC of the battery cell according to any one of claims 2 to 4, characterized by, Before the control of the target battery cell to perform gradient discharging to obtain the relationship curve between the static SOC and the open-circuit voltage, the method comprises the step of: controlling the target battery cell to perform a complete discharging-complete charging cycle based on preset charging and discharging parameters.

6. The method of estimating SOC of a battery cell according to claim 5, wherein, The control of the target battery cell to perform the complete discharging-complete charging cycle based on the preset charging and discharging parameters comprises the steps of: controlling the target battery cell to perform complete discharging at a preset speed at a preset temperature, and then controlling the target battery cell to perform complete charging at the preset speed when the complete discharging is completed; obtaining a static duration when the complete charging is completed; if the static duration reaches a preset duration threshold, obtaining a full-charge open-circuit voltage and a capacity of the target battery cell.

7. The method of estimating SOC of a battery cell according to any one of claims 2 to 4, characterized by, Before the obtaining of the current state of the target battery cell, the method comprises the step of: obtaining a charging and discharging cutoff voltage, a protection voltage, an ampere-hour integration algorithm, and an open-circuit voltage algorithm; prewriting the charging and discharging cutoff voltage, the protection voltage, the ampere-hour integration algorithm, and the open-circuit voltage algorithm into an integrated circuit control program of a battery management system.

8. A device for estimating the state of charge (SOC) of a battery cell, characterized in that, The method comprises: a first obtaining unit configured to obtain a current state of a target battery cell; a first processing unit configured to, if the current state is a charging and discharging state, estimate dynamic SOC data of the target battery cell according to a preset ampere-hour integration algorithm. A second processing unit is configured to, if the current state is a non-working state, acquire a non-working state duration, and when the non-working state duration reaches a preset duration threshold, calibrate the dynamic SOC data according to a preset open-circuit voltage algorithm to obtain target SOC data, wherein the preset open-circuit voltage algorithm is based on a relationship curve between a static SOC and an open-circuit voltage.

9. An apparatus for estimating SOC of a battery cell, comprising: Processor, memory, and computer program stored in the memory and executable on the processor, characterized in that the processor, when executing the computer program, implements the steps of the method according to any one of claims 1 to 7.

10. A computer-readable storage medium storing a computer program, the computer program comprising instructions that, when executed by a computer, cause the computer to perform the method of any one of claims 1 to 9. The computer program is executed by the processor to implement the method according to any one of claims 1 to 7.

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