A calibration method, device and vehicle for SOC value

Abstract

An embodiment of the present invention provides a method, device, and vehicle for calibrating the SOC value. The method includes: during the process of charging the battery, determining the voltage inflection point of the battery charging according to the charging curve of the battery, and the voltage value corresponding to the voltage inflection point; calculating the true SOC value corresponding to the voltage inflection point according to the capacity value corresponding to the cut-off voltage when the battery is fully charged, the capacity value corresponding to the voltage inflection point, and the current available capacity value of the battery determined by the battery management system; and calibrating the SOC value of the battery according to the true SOC value corresponding to the voltage inflection point. The method and device provided by the embodiment of the present invention can determine the true SOC value according to the voltage inflection point of the battery charging curve, and can automatically calibrate the SOC value of the battery after the battery is put into use, so that the SOC value of the battery is not affected by factors such as temperature and battery aging.

Description

Technical Field

[0001] The present invention relates to the technical field of storage batteries, and particularly to a calibration method for SOC value, a calibration device for SOC value, and a vehicle. Background Art

[0002] For many products that need to use storage batteries, users often need to accurately know how much power is left in the product. The remaining capacity of the battery is also called the state of charge SOC (State of Charge), which is a parameter reflecting the percentage of the current power in the overall available capacity of the storage battery, and is usually expressed as a percentage. The value range of SOC is 0-1. When SOC = 0, it means the battery is completely discharged, and when SOC = 1, it means the battery is fully charged. For a storage battery with a battery management system BMS (Battery Management System), the BMS also needs to accurately know the current SOC of the storage battery to accurately implement various scheduling and operations.

[0003] The SOC value of the battery cannot be directly measured and can only be estimated by internal parameters such as the battery terminal voltage, charge and discharge current, and internal resistance. The current common practice is to perform a test of the SOC value before the battery is put into use, and use the test result for the entire life stage after the battery product is put into use.

[0004] However, in fact, the internal parameters of the battery are often affected by various uncertain factors such as battery aging, environmental temperature change, and battery discharge state. Under the influence of various environmental parameters and state parameters, the SOC value calibrated in the laboratory does not conform to the SOC value in the actual use of the battery product, which seriously affects the BMS to accurately perform scheduling and operations, and also makes users unable to view the accurate remaining power, seriously affecting the user experience. Therefore, the accurate estimation of the SOC value has become an urgent problem to be solved in the development of storage battery products. Summary of the Invention

[0005] In order to solve the above problems, embodiments of the present invention propose a calibration method for SOC value, a calibration device for SOC value, and a vehicle, aiming to accurately calibrate the SOC value.

[0006] Embodiments of the present invention provide a calibration method for SOC value, and the method includes:

[0007] During the process of charging the battery, according to the charging curve of the battery, determine the voltage inflection point of the battery charging and the voltage value corresponding to the voltage inflection point;

[0008] Calculate the true SOC value corresponding to the voltage inflection point based on the capacity value corresponding to the cut-off voltage when the battery is fully charged, the capacity value corresponding to the voltage inflection point, and the current available capacity value of the battery determined by the battery management system;

[0009] Calibrate the SOC value of the battery according to the true SOC value corresponding to the voltage inflection point.

[0010] Optionally, it further includes:

[0011] Before charging the battery, detect the historical charge and discharge times of the battery;

[0012] Calibrating the SOC value of the battery according to the true SOC value corresponding to the voltage inflection point includes:

[0013] When the historical charge and discharge times of the battery are within a preset range, the battery management system calculates the SOC value of the battery according to the charge and discharge capacity of the battery;

[0014] When the historical charge and discharge times of the battery reach the upper limit value of the preset range, re-determine the voltage inflection point of battery charging and the true SOC value corresponding to this voltage inflection point to calibrate the SOC value of the battery again.

[0015] Optionally, it further includes:

[0016] Determine the current temperature value of the battery;

[0017] When the current temperature value exceeds the historical temperature value range of the battery, calculate the true SOC value corresponding to the voltage inflection point based on the capacity value corresponding to the cut-off voltage when the battery is fully charged, the capacity value corresponding to the voltage inflection point, and the current available capacity value of the battery determined by the battery management system at the current temperature value.

[0018] Optionally, during the process of charging the battery, determine the voltage inflection point of battery charging and the voltage value corresponding to the voltage inflection point according to the charging curve of the battery, including:

[0019] During the process of charging the battery, monitor the slope of the voltage-time charging curve;

[0020] When the slope is greater than 0 and the duration of the continuous increase of the slope reaches a preset duration, determine the curve inflection point when the slope starts to increase as the voltage inflection point.

[0021] Optionally, calculating the true SOC value corresponding to the voltage inflection point based on the capacity value corresponding to the cut-off voltage when the battery is fully charged, the capacity value corresponding to the voltage inflection point, and the current available capacity value of the battery determined by the battery management system includes:

[0022] Calculate the first battery capacity value corresponding to the voltage inflection point;

[0023] Calculate the second battery capacity value corresponding to the cut-off voltage value when the battery is fully charged;

[0024] Calculate the battery capacity difference between the first battery capacity value and the second battery capacity value, where the battery capacity difference represents the amount of electricity charged into the battery from the voltage inflection point to the cut-off voltage;

[0025] Calculate the SOC change value from the voltage inflection point to the cut-off voltage according to the current available battery capacity value determined by the battery management system and the battery capacity difference;

[0026] Calculate the true SOC value corresponding to the voltage inflection point according to the SOC change value.

[0027] Optionally, calibrate the SOC value of the battery according to the true SOC value corresponding to the voltage inflection point, including:

[0028] During the next charging process of the battery, if the SOC value of the battery reaches the true SOC value corresponding to the voltage inflection point earlier than the charging curve of the battery reaches the voltage inflection point, the SOC value of the battery remains unchanged after reaching the true SOC value corresponding to the voltage inflection point until the charging curve of the battery reaches the voltage inflection point.

[0029] Optionally, calibrate the SOC value of the battery according to the true SOC value corresponding to the voltage inflection point, including:

[0030] During the next charging process of the battery, if the SOC value of the battery reaches the true SOC value corresponding to the voltage inflection point later than the charging curve of the battery reaches the voltage inflection point, after the charging curve of the battery reaches the voltage inflection point, adjust the SOC value of the battery to the true SOC value corresponding to the voltage inflection point.

[0031] An embodiment of the present invention also provides a calibration device for the SOC value, including:

[0032] A voltage inflection point determination unit, configured to determine the voltage inflection point of battery charging and the voltage value corresponding to the voltage inflection point according to the charging curve of the battery during the charging process of the battery;

[0033] An SOC calculation unit, configured to calculate the true SOC value corresponding to the voltage inflection point according to the capacity value corresponding to the cut-off voltage when the battery is fully charged, the capacity value corresponding to the voltage inflection point, and the current available battery capacity value determined by the battery management system;

[0034] The SOC calibration unit is used to calibrate the SOC value of the battery according to the true SOC value corresponding to the voltage inflection point.

[0035] Optionally, the device further includes:

[0036] The charge and discharge times detection unit is used to detect the historical charge and discharge times of the battery before charging the battery;

[0037] The SOC calibration unit includes:

[0038] The SOC value calculation unit is used to calculate the SOC value of the battery by the battery management system according to the charge and discharge capacity of the battery when the historical charge and discharge times of the battery are within a preset range;

[0039] The first SOC value calibration unit is used to re-determine the voltage inflection point of battery charging and the true SOC value corresponding to the voltage inflection point when the historical charge and discharge times of the battery reach the upper limit value of the preset range, so as to calibrate the SOC value of the battery again.

[0040] Optionally, the device further includes:

[0041] The current temperature determination unit is used to determine the current temperature value of the battery;

[0042] The second SOC value calibration unit is used to calculate the true SOC value corresponding to the voltage inflection point according to the capacity value corresponding to the cut-off voltage when the battery is fully charged, the capacity value corresponding to the voltage inflection point, and the current available capacity value of the current battery determined by the battery management system if the current temperature value exceeds the historical temperature value range of the battery.

[0043] Optionally, the device includes:

[0044] The first charging curve monitoring unit is used to monitor the slope of the voltage-time charging curve during the charging process of the battery;

[0045] The first voltage inflection point determination unit is used to determine the curve inflection point when the slope starts to increase as the voltage inflection point when the slope is greater than 0 and the duration of continuous increase of the slope reaches a preset duration.

[0046] Optionally, the device includes:

[0047] The first battery capacity value calculation unit is used to calculate the first battery capacity value corresponding to the voltage inflection point;

[0048] The second battery capacity value calculation unit is used to calculate the second battery capacity value corresponding to the cut-off voltage value when the battery is fully charged;

[0049] A battery capacity difference calculation unit for calculating a battery capacity difference between the first battery capacity value and the second battery capacity value, where the battery capacity difference represents the amount of electricity charged into the battery during the period from the voltage inflection point to the cut-off voltage;

[0050] An SOC change value calculation unit for calculating an SOC change value during the period from the voltage inflection point to the cut-off voltage according to the current available battery capacity value determined by the battery management system and the battery capacity difference;

[0051] A true SOC value calculation unit for calculating a true SOC value corresponding to the voltage inflection point according to the SOC change value.

[0052] Optionally, the device includes:

[0053] An SOC value first calibration unit for, during the next charging of the battery, if the SOC value of the battery reaches the true SOC value corresponding to the voltage inflection point earlier than the charging curve of the battery reaches the voltage inflection point, the SOC value of the battery remains unchanged after reaching the true SOC value corresponding to the voltage inflection point until the charging curve of the battery reaches the voltage inflection point.

[0054] Optionally, the device includes:

[0055] An SOC value second calibration unit for, during the next charging of the battery, if the SOC value of the battery reaches the true SOC value corresponding to the voltage inflection point later than the charging curve of the battery reaches the voltage inflection point, after the charging curve of the battery reaches the voltage inflection point, adjusting the SOC value of the battery to the true SOC value corresponding to the voltage inflection point.

[0056] An embodiment of the present invention further provides a vehicle, and the battery management system of the vehicle is used to execute the steps of any one of the above methods.

[0057] As can be seen from the above technical solutions, the embodiments of the present invention provide a method, an apparatus, and a vehicle for calibrating the SOC value. During the process of charging the battery, the voltage inflection point of the battery charging and the current available battery capacity value are determined, and the true SOC value corresponding to the voltage inflection point is calculated; the SOC value of the battery is calibrated according to the true SOC value. Through the method and apparatus provided by the embodiments of the present invention, the true SOC value corresponding to the voltage inflection point is determined according to the voltage inflection point of the battery charging curve and the true available capacity value of the battery, and the SOC value of the battery is calibrated accordingly. It can be realized by adding software to the controller of the battery management system to automatically calibrate the SOC value of the battery after the battery is put into use, reduce the influence of factors such as temperature and battery aging on the battery SOC value, enable the battery management system to accurately understand the current SOC of the storage battery, and then accurately realize various scheduling and operations, and accurately display the remaining power. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 is a flowchart of the steps of a method for calibrating the SOC value provided by an embodiment of the present invention;

[0059] Figure 2 is a flowchart of the steps of a method for calculating the true SOC value provided by an embodiment of the present invention;

[0060] Figure 3 is a flowchart of the steps of an online test for the true SOC value provided by an embodiment of the present invention;

[0061] Figure 4 is a structural block diagram of an apparatus for calibrating the SOC value provided by an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0062] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0063] The SOC value of the storage battery represents the remaining battery capacity. If the estimation of the SOC value is inaccurate, it will affect the scheduling management of the battery management system BMS and the remaining power value displayed to the user. For example, if the SOC value displayed by the battery is 20%, but the actual SOC value is only 5%, the user cannot correctly realize that the battery is about to run out and make timely decisions.

[0064] Currently, the SOC value of a storage battery generally uses the test value in the laboratory, without considering the influence of battery aging, environmental temperature change, and battery discharge state (such as the driving state of a vehicle). As the number of charge and discharge cycles of the battery increases, it leads to battery aging. Coupled with the decrease in battery efficiency caused by low temperature, the SOC value of the storage battery may deviate from the actual value by more than 20-40%.

[0065] The lithium iron phosphate lithium-ion battery is a storage battery applied in various energy storage devices, electric vehicles, high-power electric tools and many other fields, with characteristics such as high energy density, high safety, long life, and the ability to achieve high-rate charging. Taking the lithium iron phosphate lithium-ion battery as an example, currently, to determine the SOC value of the lithium iron phosphate lithium-ion battery, usually a full charge test is completed in the laboratory to determine the SOC value corresponding to the internal parameters of the battery in each state, and the calibration of the SOC value is completed. The SOC value after this calibration will be used as the standard SOC value and applied to the entire life stage after the battery product is put into use. Since the accurate estimation of SOC will involve the non-linear influence of open-circuit voltage, instantaneous current, charge and discharge rate, environmental temperature, battery temperature, parking time, self-discharge rate, Coulomb efficiency, resistance characteristics, initial SOC value, DOD (depth of discharge), etc., these external characteristics are affected by different materials, different processes, etc., and affect each other. Obviously, only using the data of one test in the laboratory as the SOC value and no longer considering the influence of factors such as battery aging, environmental temperature change, and battery discharge state will make the estimation of the SOC value of the battery inaccurate during use.

[0066] In view of the above problems, the applicant of the present invention proposes a calibration method for the SOC value, a calibration device for the SOC value, and a vehicle, which realize the on-line calibration of the battery SOC value by collecting the charging data during the on-line charging process of the battery and calculating the true SOC value of the voltage inflection point of the charging curve.

[0067] Refer to Figure 1 , Figure 1 is the step flow chart of a calibration method for the SOC value provided by an embodiment of the present invention. As Figure 1 shown, the method specifically includes the following steps:

[0068] Step S31: During the charging process of the battery, according to the charging curve of the battery, determine the voltage inflection point of the battery charging and the voltage value corresponding to the voltage inflection point.

[0069] In this embodiment, the charging curve is the voltage-time curve during the charging process, and the voltage inflection point refers to the inflection point before the charging curve enters the following charging stage: the first derivative dV / dt of the voltage with respect to time is greater than 0. Therefore, using the SOC value of the charging inflection point as the calibration standard will make the calibration of the SOC value of the storage battery more accurate.

[0070] Before this step is implemented, the battery status can also be detected first. When the recording requirements are met, parameters such as charging time, voltage, current, temperature, and capacity change are recorded until the battery is fully charged and the recording is completed.

[0071] Among them, the recording requirements can be related parameters preset before leaving the factory. For example, the number of battery charge and discharge cycles, or the change value of the ambient temperature where the battery is located, etc. If the requirements are met, this recording can start.

[0072] The recording requirements can also be the triggering operation of the user. For example, an option of "battery capacity calibration" is provided to the user in the user interface. After the user activates this option, relevant data will be recorded during the next charging, and the SOC value of the battery will be calibrated.

[0073] Step S32: Calculate the true SOC value corresponding to the voltage inflection point according to the capacity value corresponding to the cut-off voltage when the battery is fully charged, the capacity value corresponding to the voltage inflection point, and the current available capacity value of the battery determined by the battery management system.

[0074] The battery management system is the core technology of intelligent battery packs and is widely used in various battery packs or battery groups, especially in the battery groups of electric vehicles. The battery management system can detect the state parameters of the battery, including: single-cell voltage, internal resistance, temperature, total voltage, and total current, and can also calculate the charge and discharge capacity and evaluate the battery state. In addition, the battery management system BMS can calculate the current available capacity value of the battery according to the current state of the battery, that is, the maximum available capacity of the battery in the current state. At present, there are many methods for estimating the current available capacity value of the battery management system, including the open-circuit voltage method, ampere-hour integration method, internal resistance method, Kalman filtering method, and neural network method, etc., which can calculate the absolute capacity value of the battery more accurately.

[0075] When calculating the capacity value after battery charging, the charge and discharge capacity calculation method is generally used, that is, the pre-charge power of the battery plus the charged power to obtain the capacity value of the battery after charging. For example, the pre-charge battery capacity value is 5Ah, and the charged battery capacity value calculated according to parameters such as charging current, voltage, and time is 60Ah, then the capacity value after charging is 65Ah; if the pre-charge battery capacity value is erroneously recorded as 8Ah, the capacity value after charging will be erroneously recorded as 68Ah. That is, if the pre-charge battery capacity is inaccurate, the capacity value after charging is also inaccurate. Therefore, this embodiment preferentially considers calculating the difference between the capacity value corresponding to the cut-off voltage and the capacity value corresponding to the voltage inflection point to avoid the influence caused by the error of the starting point capacity value of charging.

[0076] Refer to Figure 2 , Figure 2It is a flowchart of the steps of a method for calculating the true SOC value provided by an embodiment of the present invention. As Figure 2 shown, in this embodiment, a method for calculating the true SOC value corresponding to the voltage inflection point is provided. By calculating the capacity difference between the capacity value corresponding to the cut-off voltage and the capacity value corresponding to the voltage inflection point, and then obtaining the SOC change value according to the ratio of the capacity difference and the current available capacity value of the battery, finally, the true SOC value corresponding to the voltage inflection point is calculated. Specifically, it includes the following steps:

[0077] S321, calculate the first battery capacity value A1 corresponding to the voltage inflection point;

[0078] S322, calculate the second battery capacity value A2 corresponding to the cut-off voltage value when the battery is fully charged;

[0079] S323, calculate the battery capacity difference △A between the first battery capacity value A1 and the second battery capacity value A2, and the battery capacity difference represents the amount of electricity charged into the battery from the voltage inflection point to the cut-off voltage;

[0080] S324, according to the current available capacity value of the battery determined by the battery management system and the battery capacity difference, calculate the SOC change value △SOC = △A / C from the voltage inflection point to the cut-off voltage;

[0081] S325, calculate the true SOC value corresponding to the voltage inflection point according to the SOC change value.

[0082] Optionally, subtracting the SOC change value from the voltage inflection point to the cut-off voltage by 1 can obtain the true SOC value corresponding to the voltage inflection point, that is, SOC = 1 - △SOC.

[0083] For example, if the first battery capacity value is 92 Ah, the second battery capacity value is 98 Ah, the amount of electricity charged into the battery from the voltage inflection point to the cut-off voltage is 6 Ah, and the current available capacity value of the battery determined by the battery management system is 100 Ah, then the SOC change value from the voltage inflection point to the cut-off voltage is 6%, and the true SOC value corresponding to the voltage inflection point is 1 - 6% = 94%.

[0084] Combined with the above embodiments, since the method for determining the battery SOC value through the voltage inflection point has characteristics such as automatic calculation and relatively high credibility of the calculation results, the method for confirming the voltage inflection point and the true SOC value of the present invention ensures the accuracy of SOC calibration while making the method easy to be written into the software of the battery management system, so as to realize the automatic confirmation and calibration of the SOC value during the use of the battery by the user.

[0085] Step S33: Calibrate the SOC value of the battery according to the true SOC value corresponding to the voltage inflection point.

[0086] According to the foregoing steps, after the battery is fully charged once in this embodiment, the true SOC value corresponding to the voltage inflection point of the charging curve can be calculated. Correspondingly, it is preferably considered to calibrate the SOC value of the battery by using this true SOC value during the next charging process of the battery.

[0087] In one implementation, the method for calibrating the overestimated SOC value of the battery includes:

[0088] During the next charging process of the battery, if the SOC value of the battery reaches the true SOC value corresponding to the voltage inflection point earlier than the charging curve of the battery reaches the voltage inflection point, the SOC value of the battery remains unchanged after reaching the true SOC value corresponding to the voltage inflection point until the charging curve of the battery reaches the voltage inflection point.

[0089] Exemplarily, if the calculated true SOC value corresponding to the voltage inflection point is 91%, during the next charging process, the SOC value fed back by the battery reaches 91% in advance, while the charging curve of the battery actually has not reached the voltage inflection point yet, which indicates that the battery's power is overestimated. It can be displayed as 91% until the charging curve reaches the voltage inflection point and then calibrated. This is because when the battery's power is overestimated, the actual SOC value is lower than the fed-back SOC value. For example, the actual SOC value is 85% and the fed-back SOC value is 91% (reaching the true SOC value corresponding to the voltage inflection point). If directly calibrated and adjusted from 91% to 85%, it may affect the scheduling strategy of the BMS, and at the same time, the power display jumps down, which will affect the user experience.

[0090] Among them, the method for judging whether the charging curve of the battery reaches the voltage inflection point can be the same as the method for judging the voltage inflection point during the previous charging process, or it can be judged whether the charging curve of the battery reaches the voltage inflection point by judging whether the voltage value reaches the voltage value corresponding to the voltage inflection point during the previous charging process.

[0091] In one implementation, the method for calibrating the underestimated SOC value of the battery includes:

[0092] During the next charging process of the battery, if the SOC value of the battery reaches the true SOC value corresponding to the voltage inflection point later than the charging curve of the battery reaches the voltage inflection point, after the charging curve of the battery reaches the voltage inflection point, adjust the SOC value of the battery to the true SOC value corresponding to the voltage inflection point.

[0093] Exemplarily, if the calculated true SOC value corresponding to the voltage inflection point is 91%, during the next charging process, if the charging curve of the battery has actually reached the voltage inflection point this time, but the SOC value fed back by the battery is only 85%, it indicates that the battery's power is falsely low. Then, the SOC value of the battery can be directly calibrated from 85% to 91%. This is because the actual battery capacity of the battery is higher, the impact of adjusting the BMS scheduling strategy upward is relatively small, and the impact on the user's perception is also small when the power display data is adjusted upward.

[0094] In this embodiment, of course, the process of adjusting the falsely low power can also be optimized. By calibrating in batches, the impact on the BMS scheduling strategy and the user's perception can be reduced. For example, if the calculated true SOC value corresponding to the voltage inflection point is 91%, and the SOC value fed back by the battery at the voltage inflection point during charging is only 85%, the SOC value of the battery can be calibrated in batches to 86%, 87%, 88%, 89%, 90%, 91% within a preset time, so as to minimize the impact on the BMS scheduling strategy and the user's perception.

[0095] Since the main factors causing the error of the battery's SOC value are battery aging and ambient temperature, after each calibration of the SOC value, the battery can be not calibrated within a certain number of charge-discharge cycles and temperature change range. During this period, the battery management system can determine the SOC value through conventional charge-discharge capacity calculations.

[0096] In view of this, in one implementation, the conditions for calibrating the SOC value of the battery can be set based on the historical charge-discharge times of the battery, so as to avoid unnecessary frequent calibration on the premise of reducing the impact of battery aging, including:

[0097] Before charging the battery, detect the historical charge-discharge times of the battery;

[0098] According to the true SOC value corresponding to the voltage inflection point, calibrate the SOC value of the battery, including:

[0099] When the historical charge-discharge times of the battery are within the preset range, the battery management system calculates the SOC value of the battery according to the charge-discharge capacity of the battery;

[0100] When the historical charge-discharge times of the battery reach the upper limit value of the preset range, re-determine the voltage inflection point of battery charging and the true SOC value corresponding to this voltage inflection point, so as to calibrate the SOC value of the battery again.

[0101] Exemplarily, it can be set that every time the full charge and full discharge times reach 100 times, that is, a calibration of the SOC value is performed. Then the preset range of the historical charge and discharge times is 100, 200, 300... For further exemplary illustration, the true SOC value corresponding to the charging inflection point can be determined at the 100th full charge, and the SOC value of the battery can be calibrated using the true SOC value at the 101st full charge.

[0102] In this embodiment, after each calibration of the SOC value, the battery management system only needs to calculate the SOC value of the battery according to the charge and discharge capacity until the next calibration of the SOC value.

[0103] In one implementation manner, the conditions for calibrating the SOC value of the battery can also be set based on the historical ambient temperature of the battery, so as to avoid unnecessary frequent calibration on the premise of reducing the influence of the ambient temperature, including:

[0104] Determine the current temperature value of the battery;

[0105] If the current temperature value exceeds the historical temperature value range of the battery, then according to the capacity value corresponding to the cut-off voltage when the battery is fully charged, the capacity value corresponding to the voltage inflection point, and the current available capacity value of the current battery determined by the battery management system at the current temperature value, calculate the true SOC value corresponding to the voltage inflection point.

[0106] In this embodiment, the battery management system can be used to detect and record the historical temperature of the battery. When the battery reaches a temperature value beyond the historical range, it may cause an error in the estimation of the SOC value. Under such conditions, the SOC value can be calibrated again.

[0107] Exemplarily, if the first range of the historical temperature value of the battery records is 15°C to 35°C, and it is set that if it exceeds this range by 5°C, the SOC value is calibrated again, then the historical temperature value range of the battery is 10°C to 40°C. When the battery is affected by the ambient temperature and it is detected that the ambient temperature where the battery is located is continuously lower than 10°C for a long time, the SOC value of the battery can be calibrated again.

[0108] Figure 3 This is a flowchart of the steps for online testing the true SOC value provided by an embodiment of the present invention. Refer to Figure 3 As shown, after the battery is put into use online in this embodiment, the following steps are executed:

[0109] S41, Detect the charging state of the battery, and it is detected that the battery is charging (fast charging or slow charging);

[0110] S42, When the recording requirements are met, start recording time, voltage, current, temperature, and capacity change;

[0111] S43, Record until full and end the charging;

[0112] S44, Online analysis, confirm data such as voltage inflection points and SOC values according to changes in relevant calculations;

[0113] S45, Write the analyzed data into the SOC control strategy for calibration use next time;

[0114] S46, For the next charging, if the recording conditions are met, continue to record data.

[0115] Through this embodiment, monitor the charging state of the battery. Each time during charging, when it is detected that the recording requirements are met, the requirements can be set as the number of charge and discharge cycles of the battery and / or the battery temperature, and then data is recorded. Furthermore, confirm the voltage inflection point and the true SOC value to achieve regular SOC value calibration.

[0116] In addition, considering that the voltage of the battery may fluctuate during charging, and in this case, it is easy to misjudge the battery inflection point. Therefore, in one embodiment, a method for determining the voltage inflection point is provided, including:

[0117] During the process of charging the battery, monitor the slope of the voltage-time charging curve;

[0118] When the slope is greater than 0 and the duration for which the slope continuously increases reaches a preset duration, determine the curve inflection point when the slope starts to increase as the voltage inflection point.

[0119] That is, the following stage needs to be maintained for a long enough time to determine the curve inflection point when the curve slope starts to increase as the voltage inflection point: the first derivative of voltage with respect to time dV / dt is greater than 0.

[0120] Exemplarily, the preset duration can be set according to the charging voltage fluctuation characteristics of the battery and the characteristics of the appearance of the voltage inflection point, and can be specifically set to 100ms, 300ms, etc.

[0121] Through this embodiment, prevent misjudgment of the battery inflection point caused by voltage fluctuations.

[0122] In one embodiment, the control algorithm for calibrating the SOC value can be written into the controller of the battery management system, and then it can be realized during the operation of the whole vehicle. Each time when charging, the battery management system will detect the starting voltage value of the charging. This voltage value must be before the inflection point appears. Therefore, this voltage value is at a relatively low voltage value or data on the voltage platform. Then it judges whether the conditions for collecting and recording data are met. If not, no recording is performed. If the conditions are met, it starts to record the changing data of voltage, current, temperature, and capacity over time and stores them in the controller. It must collect data until it is fully charged. If it is not fully charged, the collected data is invalidated. The collected data that meets the conditions is analyzed.

[0123] Through the above embodiments, the method for calibrating the SOC value provided by the present invention can write software into the battery management system, accurately calculate the voltage inflection point value and the SOC value at this temperature according to the charging data online, realize the automatic confirmation of the voltage inflection point and the true SOC value, and automatically calibrate the SOC value of the battery, without the need to spend additional time for separate testing, saving time, manpower, material resources and costs. In addition, by setting the SOC calibration conditions for the battery during online use, the true SOC value is continuously iteratively updated to conform to the user's usage environment, eliminating the influence of aging factors and making the calibration of the true SOC more accurate.

[0124] Based on the same inventive concept, an embodiment of the present invention also provides a calibration device 60 for the SOC value. Figure 4 It is a structural block diagram of a calibration device 60 for the SOC value provided by an embodiment of the present invention. As Figure 4 shown, the device 60 includes:

[0125] A voltage inflection point determination unit 61, configured to determine the voltage inflection point of the battery charging and the voltage value corresponding to the voltage inflection point according to the charging curve of the battery during the charging process of the battery;

[0126] An SOC calculation unit 62, configured to calculate the true SOC value corresponding to the voltage inflection point according to the capacity value corresponding to the cut-off voltage when the battery is fully charged, the capacity value corresponding to the voltage inflection point, and the currently available capacity value of the battery determined by the battery management system;

[0127] An SOC calibration unit 63, configured to calibrate the SOC value of the battery according to the true SOC value corresponding to the voltage inflection point.

[0128] Optionally, the device further includes:

[0129] A charge and discharge times detection unit, configured to detect the historical charge and discharge times of the battery before charging the battery;

[0130] The SOC calibration unit 63 includes:

[0131] An SOC value calculation unit, configured to, when the historical charge and discharge times of the battery are within a preset range, calculate the SOC value of the battery by the battery management system according to the charge and discharge capacity of the battery;

[0132] An SOC value first calibration unit, configured to, when the historical charge and discharge times of the battery reach the upper limit value of the preset range, re-determine the voltage inflection point of battery charging and the true SOC value corresponding to the voltage inflection point, so as to calibrate the SOC value of the battery again.

[0133] Optionally, the device further includes:

[0134] A current temperature determination unit, configured to determine the current temperature value of the battery;

[0135] An SOC value second calibration unit, configured to, if the current temperature value exceeds the historical temperature value range of the battery, calculate the true SOC value corresponding to the voltage inflection point according to the capacity value corresponding to the cut-off voltage when the battery is fully charged, the capacity value corresponding to the voltage inflection point, and the current available capacity value of the current battery determined by the battery management system at the current temperature value.

[0136] Optionally, the device includes:

[0137] A charging curve first monitoring unit, configured to monitor the slope of the voltage-time charging curve during the charging process of the battery;

[0138] A voltage inflection point first determination unit, configured to, when the slope is greater than 0 and the duration of continuous increase of the slope reaches a preset duration, determine the curve inflection point when the slope starts to increase as the voltage inflection point.

[0139] Optionally, the device includes:

[0140] A first battery capacity value calculation unit, configured to calculate the first battery capacity value corresponding to the voltage inflection point;

[0141] A second battery capacity value calculation unit, configured to calculate the second battery capacity value corresponding to the cut-off voltage value when the battery is fully charged;

[0142] A battery capacity difference calculation unit, configured to calculate the battery capacity difference between the first battery capacity value and the second battery capacity value, where the battery capacity difference represents the amount of electricity charged into the battery from the voltage inflection point to the cut-off voltage;

[0143] An SOC change value calculation unit, configured to calculate the SOC change value from the voltage inflection point to the cut-off voltage according to the current available capacity value of the current battery determined by the battery management system and the battery capacity difference;

[0144] A true SOC value calculation unit, configured to calculate a true SOC value corresponding to the voltage inflection point according to the SOC change value.

[0145] Optionally, the device includes:

[0146] An SOC value first calibration unit, configured to, in the process of charging the battery next time, if the SOC value of the battery reaches the true SOC value corresponding to the voltage inflection point and is earlier than the charging curve of the battery reaching the voltage inflection point, then the SOC value of the battery remains unchanged after reaching the true SOC value corresponding to the voltage inflection point until the charging curve of the battery reaches the voltage inflection point.

[0147] Optionally, the device includes:

[0148] An SOC value second calibration unit, configured to, in the process of charging the battery next time, if the SOC value of the battery reaches the true SOC value corresponding to the voltage inflection point and is later than the charging curve of the battery reaching the voltage inflection point, then after the charging curve of the battery reaches the voltage inflection point, adjust the SOC value of the battery to the true SOC value corresponding to the voltage inflection point.

[0149] Based on the same inventive concept, an embodiment of the present invention further provides a vehicle, and a battery management system of the vehicle is configured to execute the steps of the method described in any one of the above embodiments.

[0150] Each embodiment in this specification is described in a progressive manner. Each embodiment focuses on the differences from other embodiments. The same and similar parts among the embodiments can be referred to each other.

[0151] Those skilled in the art should understand that the embodiments of the present invention can be provided as a method, a device, or a computer program product. Therefore, the embodiments of the present invention can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the embodiments of the present invention can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0152] Embodiments of the present invention are described with reference to the flowcharts and / or block diagrams of methods, terminal devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, and the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing terminal devices to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing terminal devices generate a device for implementing the functions specified in one process Figure 1 one process or multiple processes and / or blocks Figure 1 or multiple blocks.

[0153] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing terminal device to work in a specific manner, so that the instructions stored in the computer-readable memory generate a manufactured article including an instruction device, and the instruction device implements the functions specified in one process Figure 1 one process or multiple processes and / or blocks Figure 1 or multiple blocks.

[0154] These computer program instructions can also be loaded onto a computer or other programmable data processing terminal device, so that a series of operation steps are executed on the computer or other programmable terminal device to generate a computer-implemented process, and thus the instructions executed on the computer or other programmable terminal device provide steps for implementing the functions specified in one process Figure 1 one process or multiple processes and / or blocks Figure 1 or multiple blocks.

[0155] Although the preferred embodiments of the embodiments of the present invention have been described, those skilled in the art can make additional changes and modifications to these embodiments once they know the basic creative concepts. Therefore, the appended claims are intended to be construed to include the preferred embodiments and all changes and modifications falling within the scope of the embodiments of the present invention.

[0156] Finally, it should also be noted that in this embodiment, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or terminal device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or elements inherent to such process, method, article or terminal device. Without further limitation, an element defined by the statement "comprising an..." does not exclude the presence of additional identical elements in the process, method, article or terminal device comprising the element.

[0157] The above has introduced in detail a method for calibrating an SOC value, a device for calibrating an SOC value, and a vehicle provided by the present invention. In this embodiment, specific examples are used to elaborate the principle and implementation manner of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. A calibration method for SOC value, characterized in that, Including: During the process of charging the battery, according to the charging curve of the battery, determine the voltage inflection point of the battery charging and the voltage value corresponding to the voltage inflection point; Calculate the true SOC value corresponding to the voltage inflection point according to the capacity value corresponding to the cut-off voltage when the battery is fully charged, the capacity value corresponding to the voltage inflection point, and the current available capacity value of the battery determined by the battery management system; Calibrate the SOC value of the battery according to the true SOC value corresponding to the voltage inflection point; Wherein, during the process of charging the battery, according to the charging curve of the battery, determine the voltage inflection point of the battery charging and the voltage value corresponding to the voltage inflection point, including: During the process of charging the battery, monitor the slope of the voltage-time charging curve; When the slope is greater than 0 and the duration of the continuous increase of the slope reaches a preset duration, determine the curve inflection point when the slope starts to increase as the voltage inflection point; Wherein, according to the capacity value corresponding to the cut-off voltage when the battery is fully charged, the capacity value corresponding to the voltage inflection point, and the current available capacity value of the battery determined by the battery management system, calculate the true SOC value corresponding to the voltage inflection point, including: Calculate the first battery capacity value corresponding to the voltage inflection point; Calculate the second battery capacity value corresponding to the cut-off voltage value when the battery is fully charged; Calculate the battery capacity difference between the first battery capacity value and the second battery capacity value, and the battery capacity difference represents the amount of electricity charged into the battery from the voltage inflection point to the cut-off voltage; Calculate the SOC change value from the voltage inflection point to the cut-off voltage according to the current available capacity value of the battery determined by the battery management system and the battery capacity difference; Calculate the true SOC value corresponding to the voltage inflection point according to the SOC change value.

2. The method according to claim 1, wherein Also including: Before charging the battery, detect the historical charge and discharge times of the battery; Calibrate the SOC value of the battery according to the true SOC value corresponding to the voltage inflection point, including: When the historical charge and discharge times of the battery are within a preset range, the battery management system calculates the SOC value of the battery according to the charge and discharge capacity of the battery; When the historical charge and discharge times of the battery reach the upper limit value of the preset range, re-determine the voltage inflection point of the battery charging and the true SOC value corresponding to the voltage inflection point to calibrate the SOC value of the battery again.

3. The method according to claim 1, characterized in that Also including: Determine the current temperature value of the battery; When the current temperature value exceeds the historical temperature value range of the battery, calculate the true SOC value corresponding to the voltage inflection point according to the capacity value corresponding to the cut-off voltage when the battery is fully charged, the capacity value corresponding to the voltage inflection point, and the current available capacity value of the battery determined by the battery management system at the current temperature value.

4. The method according to claim 1, wherein Calibrate the SOC value of the battery according to the true SOC value corresponding to the voltage inflection point, including: During the next charging process of the battery, if the SOC value of the battery reaches the true SOC value corresponding to the voltage inflection point earlier than the charging curve of the battery reaches the voltage inflection point, the SOC value of the battery remains unchanged after reaching the true SOC value corresponding to the voltage inflection point until the charging curve of the battery reaches the voltage inflection point.

5. The method according to claim 1, characterized in that, Calibrating the SOC value of the battery according to the true SOC value corresponding to the voltage inflection point includes: During the next charging process of the battery, if the SOC value of the battery reaches the true SOC value corresponding to the voltage inflection point later than the charging curve of the battery reaches the voltage inflection point, after the charging curve of the battery reaches the voltage inflection point, adjust the SOC value of the battery to the true SOC value corresponding to the voltage inflection point.

6. A calibration device for SOC value, characterized in that, Includes: A voltage inflection point determination unit, configured to determine, during the charging process of the battery, the voltage inflection point of the battery charging and the voltage value corresponding to the voltage inflection point according to the charging curve of the battery; An SOC calculation unit, configured to calculate the true SOC value corresponding to the voltage inflection point according to the capacity value corresponding to the cut-off voltage when the battery is fully charged, the capacity value corresponding to the voltage inflection point, and the current available capacity value of the battery determined by the battery management system; An SOC calibration unit, configured to calibrate the SOC value of the battery according to the true SOC value corresponding to the voltage inflection point; The voltage inflection point determination unit includes: A first charging curve monitoring unit, configured to monitor the slope of the voltage-time charging curve during the charging process of the battery; A first voltage inflection point determination unit, configured to determine the curve inflection point when the slope starts to increase as the voltage inflection point when the slope is greater than 0 and the duration of the continuous increase of the slope reaches a preset duration; The SOC calculation unit includes: A first battery capacity value calculation unit, configured to calculate the first battery capacity value corresponding to the voltage inflection point; A second battery capacity value calculation unit, configured to calculate the second battery capacity value corresponding to the cut-off voltage value when the battery is fully charged; A battery capacity difference calculation unit, configured to calculate the battery capacity difference between the first battery capacity value and the second battery capacity value, and the battery capacity difference represents the amount of electricity charged into the battery from the voltage inflection point to the cut-off voltage; An SOC change value calculation unit, configured to calculate the SOC change value from the voltage inflection point to the cut-off voltage according to the current available capacity value of the battery determined by the battery management system and the battery capacity difference; A true SOC value calculation unit, configured to calculate the true SOC value corresponding to the voltage inflection point according to the SOC change value.

7. A vehicle, characterized in that, The battery management system of the vehicle is used to execute the steps of the method according to any one of claims 1-5.

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