Cell open-circuit voltage estimation method and electronic equipment
By sampling and predicting the open-circuit voltage of the battery cell, the problem of inaccurate measurement of open-circuit voltage when the resting time is short is solved, and accurate estimation is achieved in a short time, which is applicable to portable terminals and other electronic devices.
Patent Information
- Application Number
- CN202511767953.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-27
- Publication Date
- 2026-02-03
AI Technical Summary
In existing technologies, measuring the open-circuit voltage of a battery cell requires a resting period of at least 30 minutes, which makes it impossible to accurately obtain the state of charge in application scenarios with short resting times.
By sampling the open-circuit voltage of the battery cell, the starting point of the prediction curve and the predetermined function are determined. The relationship between the predicted internal capacitance of the battery cell and the target sampling time is characterized by a linear constant, and the target predicted voltage value is estimated.
It enables accurate estimation of open-circuit voltage within a short settling time, making it suitable for applications with short settling times and improving the efficiency of cell status detection.
Smart Images
Figure CN121454375A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to battery management technology, and more particularly to a method for estimating the open-circuit voltage of a battery cell and an electronic device. Background Technology
[0002] Battery status monitoring is one of the most crucial functions for portable devices and other electronic devices. These devices generally rely on built-in batteries for power, and their user experience, battery life, and safety performance all depend heavily on the accuracy of battery status monitoring.
[0003] The OCV-SOC (Open Circuit Voltage - State of Charge) curve is a key curve characterizing the core electrochemical properties of a battery cell, reflecting the relationship between the open circuit voltage and the state of charge of the cell in a resting state. Given a known OCV-SOC curve, the state of charge of the battery cell can be obtained by measuring its open circuit voltage in a resting state.
[0004] When measuring open-circuit voltage using existing methods, it is typically necessary to first disconnect the load, ensure the charging and discharging current drops to zero or minimal current, and allow for a relatively long settling time (at least 30 minutes). Accurate OCV measurement can only be performed when the voltage fluctuation is less than a predetermined value. In other words, using existing methods to measure open-circuit voltage requires at least 30 minutes of settling before measurement can be performed to obtain OCV data. In some applications, the short settling time prevents OCV value readings, thus making it impossible to obtain SOC (State of Charge). Summary of the Invention
[0005] In view of this, embodiments of the present invention provide a method and electronic device for estimating the open-circuit voltage of a battery cell, which can predict a relatively accurate open-circuit voltage through a shorter resting time.
[0006] In a first aspect, embodiments of the present invention provide a method for estimating the open-circuit voltage of a battery cell, the method comprising: The starting point of the predicted curve is determined based on the last valid sampling time, and the open-circuit voltage at the valid sampling time satisfies a predetermined relationship with the open-circuit voltage at the previous sampling time and the next sampling time. The change of the predicted curve is determined based on the predetermined function and the open-circuit voltage corresponding to the starting point of the predicted curve. The linear constant is used to characterize the linear relationship between the predicted internal capacitance of the cell and the target sampling time. The target predicted voltage value is estimated based on the predicted curve.
[0007] In a second aspect, embodiments of the present invention provide a fuel gauge chip configured to perform the method described in the first aspect.
[0008] Thirdly, embodiments of the present invention provide an electronic device, including a battery cell, a memory, and a processor, wherein the memory is used to store one or more computer program instructions, wherein the one or more computer program instructions are executed by the processor to implement the method as described in the first aspect.
[0009] The technical solution of this invention samples the open-circuit voltage of the battery cell, determines the starting point and predetermined function of the prediction curve based on the sampling results, and determines the change of the prediction curve based on the predetermined function and the starting point of the prediction curve. Then, the target prediction voltage value is estimated through the prediction curve. Therefore, a relatively accurate open-circuit voltage can be predicted with a shorter resting time. Attached Figure Description
[0010] The above and other objects, features and advantages of the present invention will become clearer from the following description of embodiments of the invention with reference to the accompanying drawings, in which: Figure 1 This is a schematic diagram of the resting time-open circuit voltage coordinate system of a battery cell; Figure 2 This is a flowchart of the cell open-circuit voltage estimation method according to an embodiment of the present invention; Figure 3 This is a flowchart illustrating the determination of a valid sampling time that satisfies predetermined conditions, according to an embodiment of the present invention. Figure 4 This is a flowchart illustrating the calculation of linear constants based on each valid sampling time and the open-circuit voltage corresponding to the valid sampling time, according to an embodiment of the present invention. Figure 5 This is a schematic diagram of a resting time-estimated internal capacitance coordinate system according to an embodiment of the present invention; Figure 6 This is a flowchart illustrating how the change of the predicted curve is determined based on a predetermined function and the open-circuit voltage corresponding to the starting point of the predicted curve, according to an embodiment of the present invention. Figure 7 This is a comparison chart of the estimated open-circuit voltage-resting time curve and the actual open-circuit voltage-resting time curve according to an embodiment of the present invention; Figure 8 This is a schematic diagram of the open-circuit voltage estimation method according to an embodiment of the present invention; Figure 9 This is a schematic diagram of an open-circuit voltage estimation device according to an embodiment of the present invention; Figure 10 This is a schematic diagram of an electronic device according to an embodiment of the present invention. Detailed Implementation
[0011] The present application is described below based on embodiments, but it is not limited to these embodiments. In the detailed description of the present application below, certain specific details are described in detail. Those skilled in the art can fully understand the present application without these details. To avoid obscuring the substance of the present application, well-known methods, processes, flows, elements, and circuits are not described in detail.
[0012] Furthermore, those skilled in the art should understand that the accompanying drawings provided herein are for illustrative purposes only and are not necessarily drawn to scale.
[0013] Unless the context explicitly requires it, words such as "including" or "contains" throughout the application should be interpreted as including rather than exclusive or exhaustive; that is, meaning "including but not limited to".
[0014] In the description of this application, it should be understood that the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Furthermore, in the description of this application, unless otherwise stated, "a plurality of" means two or more.
[0015] Figure 1 This is a schematic diagram of the resting time versus open-circuit voltage coordinate system of a battery cell, as shown below. Figure 1 As shown, during the initial 1000 seconds of resting, the open-circuit voltage changes rapidly with the resting time. After 3000 seconds, the change slows down, gradually stabilizing. A relatively accurate SOC can be obtained from this stable voltage using the OCV-SOC curve. However, with short resting times, the measured open-circuit voltage differs significantly from the stabilized value because it is not yet stable. While with longer resting times, although a relatively accurate open-circuit voltage can be measured, the long resting time results in an excessively long acquisition period, making it difficult to implement in practical applications with short resting times.
[0016] Therefore, this invention provides a method for estimating the open-circuit voltage of a battery cell, which can estimate the open-circuit voltage of the battery cell with only a relatively short settling time, thereby shortening the acquisition cycle of the open-circuit voltage of the battery cell and making it suitable for some application scenarios with a relatively short settling time.
[0017] Figure 2 This is a flowchart of the cell open-circuit voltage estimation method according to an embodiment of the present invention, as follows: Figure 2 As shown, the method includes the following steps: Step S100: Sample the cell open-circuit voltage within a first predetermined time period at a predetermined sampling period to obtain the open-circuit voltage corresponding to each target sampling time.
[0018] Specifically, sampling is performed every predetermined sampling period until a first predetermined time is reached. For example, if the first predetermined time is 1000s and the sampling period is 100s, then the target sampling times are the times after 0s, 100s, 200s...1000s of inactivity.
[0019] In some embodiments, before sampling the cell open-circuit voltage at a predetermined sampling period within a first predetermined time, the method further includes: allowing the cell to rest for a second predetermined time. Specifically, during the initial charging / discharging or idle period, the battery generates additional polarization voltage due to ohmic polarization, electrochemical polarization, and concentration polarization, which, combined with the open-circuit voltage, causes measurement deviations. Simultaneously, the internal electrochemical reaction continues, and the uneven ion distribution causes continuous voltage fluctuations. During the resting period, the polarization effect gradually disappears, the polarization voltage approaches zero, and the internal ions redistribute uniformly, stabilizing the active material state. Therefore, allowing the cell to rest for a second predetermined time before sampling the open-circuit voltage within the sampling period is a more preferable implementation.
[0020] For example, if the second predetermined time is 200s, the first predetermined time is 1000s, and the sampling period is 100s, then the target sampling times are the times after 200s, 300s, 400s...1000s of rest. By measuring the open-circuit voltage at these target sampling times, the open-circuit voltage corresponding to each target sampling time can be obtained.
[0021] Step S200: Obtain the valid sampling time that meets the predetermined conditions based on the state of the battery cell before it is left to stand and the open circuit voltage corresponding to each target sampling time.
[0022] After determining the target sampling times and the corresponding open-circuit voltages, based on the cell's state before resting and the open-circuit voltages at each target sampling time, the target sampling times corresponding to the open-circuit voltages that meet the subsequent calculation conditions are determined as the valid sampling times. In subsequent calculations, only the open-circuit voltages corresponding to the valid sampling times are calculated.
[0023] In some embodiments, obtaining a valid sampling time that meets predetermined conditions based on the state of the battery cell before resting and the open-circuit voltage corresponding to each sampling time includes: In response to the battery cell being in a discharging state before resting, obtaining a measured first voltage difference and a measured second voltage difference at the target sampling time; if both the measured first voltage difference and the measured second voltage difference are positive, and the absolute value of the measured first voltage difference is greater than the absolute value of the measured second voltage difference, determining the target sampling time as a valid sampling time. In response to the battery cell being in a charging state before resting, obtaining a measured first voltage difference and a measured second voltage difference at the target sampling time; if both the measured first voltage difference and the measured second voltage difference are negative, and the absolute value of the measured first voltage difference is greater than the absolute value of the measured second voltage difference, determining the target sampling time as a valid sampling time. Wherein, the measured first voltage difference is the difference between the open-circuit voltage at the target sampling time and the open-circuit voltage at the previous sampling time, and the measured second voltage difference is the difference between the open-circuit voltage at the subsequent sampling time and the open-circuit voltage at the target sampling time.
[0024] The following explanation uses the example of a battery cell in a discharged state before being placed in a static state. It should be understood that the situation is similar when the battery cell is in a charging state before being placed in a discharged state. Specifically, when determining whether the i-th target sampling time is a valid sampling time, the i-th, i-1-th, and i+1-th target sampling times and the corresponding voltages for each target sampling time are determined. The first measured voltage difference is determined to be the difference between the open-circuit voltage of the i-th sampling time and the i-1-th sampling time, and the second measured voltage difference is determined to be the difference between the open-circuit voltage of the i+1-th sampling time and the i-th sampling time. First, it is determined whether the first and second measured voltage differences are positive values, because if the battery cell is in a discharged state before being placed in a static state, the open-circuit voltage will rise within the predetermined time after placement. If the measured first voltage difference and / or the measured second voltage difference is less than or equal to zero, it indicates that the open-circuit voltage is decreasing at two target sampling times, meaning it does not conform to the voltage change pattern of the static state after discharge. Therefore, this target sampling time is not considered a valid sampling time. If both the measured first voltage difference and the measured second voltage difference are greater than zero, the absolute values of the measured first voltage difference and the measured second voltage difference are further evaluated. If the absolute value of the measured first voltage difference is greater than the absolute value of the measured second voltage difference, it indicates that the rate of change of the open-circuit voltage decreases before and after the i-th target sampling time, and the cell conforms to the voltage change pattern of the static state after discharge. In this case, the i-th target sampling time can be considered a valid sampling time. If the absolute value of the measured first voltage difference is less than or equal to the absolute value of the measured second voltage difference, it indicates that the rate of change of the open-circuit voltage increases before and after the i-th target sampling time, and the cell does not conform to the voltage change pattern of the static state after discharge. In this case, the i-th target sampling time is not considered a valid sampling time.
[0025] To facilitate understanding, a flowchart is used below to explain how to determine the effective sampling time. Figure 3 This is a flowchart illustrating the determination of a valid sampling time that satisfies predetermined conditions, according to an embodiment of the present invention. Figure 3 The example used here is of a battery cell in a discharged state before being left to rest. It should be understood that the situation is similar when the battery cell is in a charging state before being left to rest. Specifically... Figure 3 As shown, determining the valid sampling time includes the following steps: Step S201: Determine the sampling time of the target to be judged.
[0026] Specifically, in the first loop of the process, the second target sampling time is determined as the target sampling time to be judged, because the first target sampling time does not have a corresponding previous target sampling time and cannot be judged. In subsequent loops, when it is necessary to determine the target sampling time to be judged, the next target sampling time after the target sampling time to be judged in the previous loop is determined as the target sampling time to be judged.
[0027] Step S202: Determine the open-circuit voltage at the sampling time of the target to be judged, the sampling time before the sampling time of the target to be judged, and the sampling time after the sampling time of the target to be judged.
[0028] Specifically, the sampling time preceding the target sampling time to be determined is the time before the sampling period of the target sampling time, and the sampling time following the target sampling time to be determined is the time after the sampling period of the target sampling time. Specifically, if the target sampling time to be determined is the third target sampling time, then the time preceding the target sampling time to be determined is the second target sampling time, and the sampling time following the target sampling time to be determined is the fourth target sampling time.
[0029] Step S203: Determine the measured first voltage difference and the measured second voltage difference.
[0030] After determining the open-circuit voltage at the target sampling time, the time preceding the target sampling time, and the time following the target sampling time, the measured first voltage difference and the measured second voltage difference are determined based on these three open-circuit voltages. Specifically, the difference between the open-circuit voltage at the target sampling time and the open-circuit voltage at the previous sampling time is taken as the measured first voltage difference, and the difference between the open-circuit voltage at the subsequent sampling time and the open-circuit voltage at the target sampling time is taken as the measured second voltage difference. For example, if the open-circuit voltage at the target sampling time is 3.1V, the open-circuit voltage at the previous sampling time is 3.2V, and the open-circuit voltage at the subsequent sampling time is 2.8V, then the measured first voltage difference is -0.1V, and the measured second voltage difference is -0.3V.
[0031] Step S204: Determine whether both the measured first voltage difference and the measured second voltage difference are positive values.
[0032] It should be understood that if the battery cell was in a charging state before being left to stand, this step is to determine whether the measured first voltage difference and the measured second voltage difference are both negative.
[0033] If so, the change in open-circuit voltage before and after the target sampling time conforms to the pattern, that is, the target sampling time may be a valid sampling time, and further judgment is needed through subsequent steps, proceeding to step S205.
[0034] If not, the change in open-circuit voltage before and after the target sampling time does not conform to the pattern, indicating that the target sampling time is not a valid sampling time. Then proceed to step S207 to determine whether all target sampling times have been judged.
[0035] Step S205: Determine whether the absolute value of the measured first voltage difference is greater than the absolute value of the measured second voltage difference.
[0036] If so, the change in open-circuit voltage conforms to the pattern, indicating that the target sampling time is a valid sampling time, and proceed to step S206.
[0037] If not, the change in open-circuit voltage does not conform to the pattern, indicating that the target sampling time is not a valid sampling time. Proceed to step S207 to determine whether all target sampling times have been judged.
[0038] Step S206: Determine the sampling time of the target to be detected as a valid sampling time.
[0039] After determining that the sampling time of the target to be detected is a valid sampling time, proceed to step S207 to determine whether all target sampling times have been judged.
[0040] Step S207: Determine whether the sampling time of the target to be judged is the second to last sampling time of the target.
[0041] Since there is no next sampling time after the last sampling time, after the validity judgment of the penultimate target sampling time, all possible valid sampling times have been judged.
[0042] If so, it indicates that the validity of all possible target sampling times has been determined, and the process proceeds to step S208.
[0043] If not, it indicates that there are still target sampling times that need to be judged for validity, and proceed to step S201.
[0044] Step S208, End.
[0045] Through steps S201-S208, valid sampling times are selected from each target sampling time, so that subsequent calculations are performed only on valid sampling times. This improves the accuracy of the target predicted voltage value calculation.
[0046] Step S300: Calculate the linear constant based on the open-circuit voltage corresponding to each valid sampling time.
[0047] After determining each valid sampling time, a predetermined function needs to be calculated based on the open-circuit voltage corresponding to each valid sampling time. This predetermined function is a linear function, comprising two linear constants: slope and intercept, used to characterize the relationship between the estimated internal capacitance and the settling time.
[0048] Extensive experiments have demonstrated that the estimated internal capacitance of a battery cell is related to its resting time as a linear function. Therefore, by calculating the estimated internal capacitance at each effective sampling time and fitting a straight line based on the estimated internal capacitance at each effective sampling time, and by calculating the slope and intercept of the fitted straight line, the slope and intercept of the linear function relationship between the estimated internal capacitance of the battery cell and its resting time can be obtained.
[0049] The specific process is as follows: Figure 4 As shown, Figure 4 This is a flowchart illustrating the calculation of a linear constant based on each valid sampling time and the open-circuit voltage corresponding to that valid sampling time, according to an embodiment of the present invention. The method includes the following steps: Step S310: Determine the estimated internal capacitance corresponding to each valid sampling time.
[0050] Among them, the estimated internal capacitance is the estimated value of the equivalent capacitance inside the cell. Its core essence is to reflect the internal capacitance characteristics of the cell formed by the effects of electrolyte ion adsorption and electrode interface polarization. It is a key parameter for cell condition assessment.
[0051] Specifically, the estimated internal capacitance corresponding to each valid sampling time is calculated using the following formula:
[0052] Where predict_C is the estimated internal capacitance, sample_T is the sampling period, delta_V12 is the measured first voltage difference, and delta_V23 is the measured second voltage difference.
[0053] Step S320: Using each valid sampling time as the abscissa and the corresponding estimated internal capacitance as the ordinate, mark the estimated internal capacitance corresponding to each valid sampling time onto the coordinate system as a marker point according to each valid sampling time and the corresponding estimated internal capacitance.
[0054] After determining the estimated internal capacitance corresponding to each valid sampling time, it is necessary to determine the slope and intercept of the predetermined functional relationship between the estimated internal capacitance and the valid sampling time. Specifically, with the valid sampling time as the x-axis and the estimated internal capacitance as the y-axis, the estimated internal capacitance corresponding to each valid sampling time is marked as a point on the coordinate system.
[0055] Step S330: Fit a straight line based on multiple marked points, and determine the slope and intercept of the straight line as linear constants.
[0056] After labeling each point onto the coordinate system, a straight line is fitted based on the multiple labeling points, and the slope and intercept of the line are determined as linear constants. Specifically, the fitting of the straight line based on multiple labeling points can be performed using various methods such as least squares method and linear regression, and this embodiment of the invention does not impose any limitations on this.
[0057] The following section will demonstrate the methods for steps S310 to S330 using a coordinate system. Figure 5 This is a schematic diagram of a coordinate system for resting time and estimated internal capacitance according to an embodiment of the present invention, as shown below. Figure 5 As shown, assuming the effective sampling times are 300s, 400s, 500s, 600s, and 700s after resting, the calculated estimated internal capacitances are 32.2μF, 43.1μF, 54.4μF, 66.7μF, and 75.8μF, respectively. By plotting the estimated internal capacitances corresponding to these effective sampling times onto a coordinate system and fitting a straight line to these plotted points, the slope and intercept of the line are calculated to be 0.1064 and 1.24, respectively.
[0058] It should be understood that when a computer performs linear fitting based on multiple marked points, it does not need to establish a coordinate system. Taking the least squares method as an example, the computer first reads the coordinate data of each marked point, determines that the fitting target is a straight line, and calculates the relevant statistical parameters of the scattered coordinates according to the principle of the least squares method, including the average value of the coordinates, the sum of the products of deviations, and the sum of squares of the deviations of individual coordinates. Then, the slope and intercept of the fitted line are solved using these statistical parameters.
[0059] Steps S100-S300 determine the effective sampling time and the linear constant of the predetermined function. After determining the linear constant and the effective sampling time, the open-circuit voltage-resting time curve following the last effective sampling time needs to be fitted using the linear constant to determine the target predicted voltage value.
[0060] It should be understood that the determination of the effective sampling time and the determination of the linear constant of the predetermined function are not limited to the above methods, and other methods can also be used to determine them.
[0061] Step S400: Determine the starting point of the predicted curve based on the last valid sampling time.
[0062] Specifically, the last valid sampling time is taken as the starting point of the open-circuit voltage-resting time curve, so that the curve can be determined from the starting point according to a predetermined function in the subsequent process.
[0063] Step S500: Determine the change of the predicted curve based on the predetermined function and the open-circuit voltage corresponding to the starting point of the predicted curve.
[0064] After determining the predetermined function through slope and intercept, i.e., estimating the change parameter of the internal capacitance with resting time, the subsequent changes of the curve are predicted based on the predetermined function and the starting point of the predicted curve. Specifically, in this embodiment of the invention, the time after two sampling periods from the last valid sampling time is taken as the first predicted time, and the time after a sampling period from the predicted time is taken as the next predicted time. The open-circuit voltage at each predicted time is calculated iteratively to obtain the open-circuit voltage corresponding to each predicted time. It should be understood that since the time after one sampling period from the last valid sampling time is the target sampling time, its corresponding open-circuit voltage has already been determined by measurement, so there is no need to estimate the voltage corresponding to this time. Therefore, the first predicted time is set as the time after this time, that is, the time after two sampling periods from the last valid sampling time.
[0065] Figure 6 This is a flowchart illustrating how the change in the predicted curve is determined based on a predetermined function and the open-circuit voltage corresponding to the starting point of the predicted curve, according to an embodiment of the present invention. Figure 6 As shown, determining the change in the predicted curve includes the following steps: Step S501: Determine the estimated time.
[0066] Specifically, the first estimated time is the time after the last valid sampling time has elapsed through the sampling period. When determining the estimated time in subsequent estimations, the estimated time is the time after the sampling period is added to the previous estimated time.
[0067] Step S502: Determine the estimated internal capacitance corresponding to the estimated time based on the estimated time and the predetermined function.
[0068] After obtaining the estimated time, the estimated internal capacitance corresponding to the estimated time is calculated using the resting time corresponding to the estimated time and a predetermined function. Specifically, since the estimated internal capacitance and the resting time have a predetermined functional relationship, and the predetermined functional relationship characterizing the estimated internal capacitance and the resting time has been calculated through fitting in steps S100-S300, the estimated internal capacitance corresponding to the estimated time can be calculated using the predetermined function.
[0069] Specifically, the estimated internal capacitance corresponding to the estimated time, determined based on the estimated time and the predetermined function, is calculated using the following formula:
[0070] Where predict_c_new is the predicted internal capacitance corresponding to the predicted time, T_new is the time from rest to the predicted time, and the predetermined function is y=kx+b.
[0071] Step S503: Determine the estimated first voltage difference at the estimated time based on the estimated internal capacitance, the estimated first voltage difference at the previous estimated time, and the sampling period.
[0072] After determining the estimated internal capacitance corresponding to the estimated time, it is necessary to determine the estimated first voltage difference at the estimated time. The estimated first voltage difference is the difference between the estimated open-circuit voltage at the estimated time and the previous estimated time. After obtaining the estimated first voltage difference at the estimated time, the open-circuit voltage at the estimated time can be determined by using the open-circuit voltage at the previous estimated time and the estimated first voltage difference at the estimated time.
[0073] Specifically, the determination of the estimated first voltage difference based on the estimated internal capacitance, the estimated first voltage difference at the previous estimation time, and the sampling period is calculated using the following formula:
[0074] Where deltaVt1_new is the estimated first voltage difference at the estimated time, deltaVt1 is the estimated first voltage difference at the previous estimated time, sample_T is the sampling period, and predict_c_new is the estimated internal capacitance corresponding to the estimated time. Specifically, when calculating the estimated first voltage difference at the first estimated time, the estimated first voltage difference at the previous estimated time is selected from the measured second voltage difference at the last valid sampling point.
[0075] Step S504: Add the estimated voltage corresponding to the previous estimated time to the estimated first voltage difference to obtain the estimated voltage corresponding to the estimated time.
[0076] After determining the estimated first voltage difference at the estimated time, the estimated first voltage difference is added to the estimated voltage corresponding to the previous estimated time to obtain the estimated open-circuit voltage at the estimated time.
[0077] Step S505: Determine whether the resting time corresponding to the estimated time is greater than or equal to the predetermined value.
[0078] If the resting time corresponding to the estimated time is greater than or equal to the predetermined value, it indicates that the predetermined number of iterative calculations has been performed, and proceed to step S506.
[0079] If the resting time corresponding to the estimated time does not exceed the predetermined value, it indicates that the number of iterations is insufficient, and it is necessary to proceed to step S501 to continue the iteration calculation.
[0080] For example, if the x-coordinate of the starting point of the curve is 800s, the sampling period is 100s, and the predetermined value is 10000s, then after 92 iterations, the resting time corresponding to the estimated time reaches 10000s, at which point the iteration is stopped.
[0081] Step S506: Determine the prediction curve based on the prediction voltage corresponding to each prediction time.
[0082] After performing a predetermined number of iterations and obtaining the predicted voltage at each predicted time, the predicted curve of open-circuit voltage versus resting time after the first predetermined time is determined.
[0083] Through steps S501-S506, iterative calculation of the estimated open-circuit voltage is achieved, thereby enabling the estimation of the open-circuit voltage over a long period of time using the open-circuit voltage at each effective sampling moment within a relatively short time. Thus, it is possible to estimate the change in open-circuit voltage using a relatively short sampling time.
[0084] Step S600: Estimate the target estimated voltage value based on the estimated curve.
[0085] The target estimated voltage value is the open-circuit voltage value ultimately estimated by the method of this embodiment of the invention. In some embodiments, estimating the target estimated voltage value based on the estimation curve specifically involves determining the voltage value corresponding to a predetermined time as the target estimated voltage value using the estimation curve. For example, if the predetermined time is the time after 10,000 seconds of rest, the open-circuit voltage corresponding to the estimation curve at 10,000 seconds is determined as the target estimated voltage value. It should be understood that, in order to improve the accuracy of the target estimated voltage value, the predetermined value in step S505 is generally used as the predetermined time.
[0086] It should be noted that, theoretically, the larger the predetermined value in step S505, i.e., the more iterations, the more accurate the calculated target estimated voltage value. However, performing too many iterations consumes a lot of computing power. Furthermore, based on extensive experimental results, the difference between the target estimated voltage value calculated with a predetermined value of 10000s and the target estimated voltage value calculated with a predetermined value of 20000s or more is very small and can be ignored. Therefore, a predetermined value of around 10000s is usually chosen to save computing power.
[0087] Figure 7This is a comparison chart of the estimated open-circuit voltage-resting time curve and the actual open-circuit voltage-resting time curve according to an embodiment of the present invention. Figure 7 As shown, the blue line represents the curve connecting the open-circuit voltages at various estimated times calculated using the method of this embodiment of the invention, while the red line represents the curve showing the actual open-circuit voltage changing with resting time. It can be seen from the figure that the open-circuit voltage curve obtained by the open-circuit voltage estimation method of this embodiment of the invention is very close to the actual curve. For example, if a predetermined time of 10000s is used to estimate the open-circuit voltage of the battery cell, the error between it and the actual open-circuit voltage is only 0.001V.
[0088] This invention samples the open-circuit voltage of the battery cell, determines the starting point and predetermined function of the prediction curve based on the sampling results, and determines the change of the prediction curve based on the predetermined function and the starting point of the prediction curve. Then, the target prediction voltage value is estimated through the prediction curve. Therefore, a relatively accurate open-circuit voltage can be predicted with a shorter resting time.
[0089] To facilitate understanding of the entire estimation method, the steps are illustrated below using a diagram. Figure 8 This is a schematic diagram of the open-circuit voltage estimation method according to an embodiment of the present invention, as shown below. Figure 8 As shown, firstly, sampling is performed at a predetermined sampling period to obtain multiple target sampling times and their corresponding open-circuit voltages. Then, valid sampling times are selected according to the rules for judging valid sampling times. After determining the valid sampling times, the estimated internal capacitance corresponding to each valid sampling time is calculated using a formula, and the estimated internal capacitance corresponding to each valid sampling time is marked on a coordinate system with the valid sampling time as the abscissa and the estimated internal capacitance as the ordinate. Then, a straight line is fitted using these marked points, and the slope and intercept of the line are determined to establish a predetermined function. This predetermined function characterizes the functional relationship between the estimated internal capacitance and the resting time. Finally, using the last valid sampling point as the starting point of the prediction curve, the open-circuit voltage corresponding to each prediction time is calculated iteratively according to the predetermined function and predetermined mathematical relationship, thus obtaining the prediction curve. After obtaining the prediction curve, the voltage value corresponding to the predetermined time is determined as the target predicted voltage value. Thus, the estimation of the open-circuit voltage of the battery cell is completed.
[0090] This invention samples the open-circuit voltage of the battery cell, determines the starting point and predetermined function of the prediction curve based on the sampling results, and determines the change of the prediction curve based on the predetermined function and the starting point of the prediction curve. Then, the target prediction voltage value is estimated through the prediction curve. Therefore, a relatively accurate open-circuit voltage can be predicted with a shorter resting time.
[0091] Based on the voltage estimation method provided in the embodiments of the present invention, the embodiments of the present invention also provide a fuel gauge chip, wherein the fuel gauge chip executes the voltage estimation method provided in the embodiments of the present invention by writing a compiled program into its non-volatile memory and running the program, thereby determining the target estimated voltage value of the electronic device.
[0092] Figure 9 This is a schematic diagram of an open-circuit voltage estimation device according to an embodiment of the present invention, as shown below. Figure 9 As shown, the open-circuit voltage estimation device includes a prediction curve start point determination unit 91, a prediction curve change determination unit 92, and an estimation unit 93. The prediction curve start point determination unit 91 determines the start point of the prediction curve based on the last valid sampling time, where the open-circuit voltage at the valid sampling time satisfies a predetermined relationship with the open-circuit voltages at the previous and subsequent sampling times. The prediction curve change determination unit 92 determines the change of the prediction curve based on a predetermined function and the open-circuit voltage corresponding to the prediction curve start point, where the predetermined function characterizes the relationship between the cell's estimated internal capacitance and the target sampling time. The estimation unit 93 estimates the target predicted voltage value based on the prediction curve.
[0093] This invention samples the open-circuit voltage of the battery cell, determines the starting point and predetermined function of the prediction curve based on the sampling results, and determines the change of the prediction curve based on the predetermined function and the starting point of the prediction curve. Then, the target prediction voltage value is estimated through the prediction curve. Therefore, a relatively accurate open-circuit voltage can be predicted with a shorter resting time.
[0094] Figure 10 This is a schematic diagram of an electronic device according to an embodiment of the present invention. (For example...) Figure 10 As shown, Figure 10 The illustrated electronic device includes at least a power management chip 101 and a battery cell 102. The power management chip includes a processor 1011 and a memory 1012. The electronic device can implement the open-circuit voltage estimation method of this embodiment of the invention through the power management chip, thereby estimating the open-circuit voltage of the battery cell 102 within a relatively short resting time. The battery cell 102 is used to store and convert electrical energy, providing continuous and stable power support for the device, and is the energy core of the device's power supply system.
[0095] The memory 1012 is adapted to store instructions or programs executable by the processor 1011. The processor 1011 can be a standalone microprocessor or a collection of one or more microprocessors. Thus, the processor 1011 executes the instructions stored in the memory 1012 to perform the method flow of the embodiment of the present invention as described above, in order to estimate the open-circuit voltage of the battery cell 102.
[0096] Those skilled in the art will understand that embodiments of this application can be provided as methods, apparatus (devices), or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-readable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.
[0097] This application is described with reference to flowchart illustrations of methods, apparatus (devices), and computer program products according to embodiments of this application. It should be understood that each step in the flowchart can be implemented by computer program instructions.
[0098] These computer program instructions may be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including an instruction means, the implementation process of which is described in the instruction means. Figure 1 The function specified in one or more processes.
[0099] These computer program instructions may also be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing device to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing device, produce instructions for implementing processes. Figure 1 A device for a function specified in one or more processes.
[0100] Another embodiment of the present invention relates to a non-volatile storage medium for storing a computer-readable program for use by a computer to execute some or all of the above-described method embodiments.
[0101] That is, those skilled in the art will understand that all or part of the steps in the methods of the above embodiments can be implemented by a program specifying the relevant hardware. This program is stored in a storage medium and includes several instructions to cause a device (which may be a microcontroller, chip, etc.) or processor to execute all or part of the steps of the methods described in the embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as a USB flash drive, a portable hard drive, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.
[0102] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.
Claims
1. A method for estimating the open-circuit voltage of a battery cell, characterized in that, The method includes: The starting point of the predicted curve is determined based on the last valid sampling time, and the open-circuit voltage at the valid sampling time satisfies a predetermined relationship with the open-circuit voltage at the previous sampling time and the next sampling time. The change of the predicted curve is determined based on the predetermined function and the open-circuit voltage corresponding to the starting point of the predicted curve. The predetermined function is a linear function used to characterize the relationship between the predicted internal capacitance of the battery cell and the target sampling time. The target predicted voltage value is estimated based on the predicted curve.
2. The method according to claim 1, characterized in that, The method further includes: The cell open-circuit voltage is sampled at a predetermined sampling period within a first predetermined time period to obtain the open-circuit voltage corresponding to each target sampling moment. Based on the state of the battery cell before it is left to stand and the open-circuit voltage corresponding to each target sampling time, obtain the valid sampling time that meets the predetermined conditions. The linear constant is calculated based on the open-circuit voltage corresponding to each valid sampling time. Wherein, the linear constants are the slope and intercept of the predetermined function.
3. The method according to claim 2, characterized in that, Before sampling the cell open-circuit voltage at a predetermined sampling period within a first predetermined time period, the method further includes: The second scheduled time for the battery cells to be left stagnant.
4. The method according to claim 2, characterized in that, The step of obtaining a valid sampling time that meets the predetermined conditions based on the state of the battery cell before resting and the open-circuit voltage corresponding to the sampling time includes: In response to the battery cell being in a discharged state before being placed still, the measured first voltage difference and the measured second voltage difference at the target sampling time are obtained. If both the measured first voltage difference and the measured second voltage difference are positive, and the absolute value of the measured first voltage difference is greater than the absolute value of the measured second voltage difference, the target sampling time is determined to be a valid sampling time. In response to the battery cell being in a charging state before being placed at rest, the measured first voltage difference and the measured second voltage difference at the target sampling time are obtained. If both the measured first voltage difference and the measured second voltage difference are negative, and the absolute value of the measured first voltage difference is greater than the absolute value of the measured second voltage difference, the target sampling time is determined to be a valid sampling time. Among them, the measured first voltage difference is the difference between the open-circuit voltage at the target sampling time and the open-circuit voltage at the previous sampling time, and the measured second voltage difference is the difference between the open-circuit voltage at the subsequent sampling time and the open-circuit voltage at the target sampling time.
5. The method according to claim 2, characterized in that, The calculation of the linear constant based on each valid sampling time and the open-circuit voltage corresponding to the valid sampling time includes: Determine the estimated internal capacitance corresponding to each valid sampling time; Using each valid sampling time as the horizontal axis and the corresponding estimated internal capacitance as the vertical axis, the estimated internal capacitance corresponding to each valid sampling time is marked on the coordinate system as a marker point according to each valid sampling time and the corresponding estimated internal capacitance. A straight line is fitted based on multiple marked points, and the slope and intercept of the line are determined as linear constants.
6. The method according to claim 5, characterized in that, The estimated internal capacitance corresponding to each valid sampling time is specifically calculated using the following formula: ； Where predict_C is the estimated internal capacitance, sample_T is the sampling period, delta_V12 is the measured first voltage difference, and delta_V23 is the measured second voltage difference.
7. The method according to claim 1, characterized in that, The step of determining the change of the predicted curve based on the predetermined function and the open-circuit voltage corresponding to the starting point of the predicted curve includes performing the following steps iteratively until the predicted time is greater than or equal to the predetermined value: The estimated time is determined based on the sampling period and the previous estimated time. The estimated internal capacitance corresponding to the estimated time is determined based on the estimated time and the predetermined function. The estimated first voltage difference at the estimated time is determined based on the estimated internal capacitance corresponding to the estimated time, the estimated first voltage difference at the previous estimated time, and the sampling period. Add the estimated voltage corresponding to the previous estimated time to the estimated first voltage difference to obtain the estimated open-circuit voltage corresponding to the estimated time. The first estimated time is the time after two sampling cycles from the last valid sampling time, and the estimated first voltage difference is the difference between the estimated time and the estimated open-circuit voltage of the previous estimated time.
8. The method according to claim 7, characterized in that, When calculating the estimated first voltage difference at the first estimated time, the estimated first voltage difference at the previous estimated time is selected from the measured second voltage difference at the last valid sampling point.
9. The method according to claim 7, characterized in that, The estimated internal capacitance corresponding to the estimated time, determined based on the estimated time and the predetermined function, is specifically calculated using the following formula: ； Where predict_c_new is the predicted internal capacitance corresponding to the predicted time, T_new is the time from rest to the predicted time, and the predicted function is y=kx+b.
10. The method according to claim 7, characterized in that, The determination of the estimated first voltage difference at the estimated time, based on the estimated internal capacitance corresponding to the estimated time, the estimated first voltage difference at the previous estimated time, and the sampling period, is specifically calculated using the following formula: ； Where deltaVt1_new is the estimated first voltage difference at the estimated time, deltaVt1 is the estimated first voltage difference at the previous estimated time, sample_T is the sampling period, and predict_c_new is the estimated internal capacitance corresponding to the estimated time.
11. The method according to claim 1, characterized in that, Specifically, estimating the target predicted voltage value based on the predicted curve involves: The voltage value at a predetermined time is determined using the predicted curve as the target predicted voltage value.
12. A fuel gauge chip, characterized in that, The fuel gauge chip is configured to perform the method as described in any one of claims 1-11.
13. An electronic device comprising a battery cell, a memory, and a processor, characterized in that, The memory is used to store one or more computer program instructions, wherein the one or more computer program instructions are executed by the processor to implement the method as described in any one of claims 1-11.