A battery state of charge estimation method, device and electronic equipment

Abstract

The application provides a battery state of charge estimation method, device and electronic equipment. The method comprises the following steps: acquiring a battery current; determining a current battery open circuit voltage at a current time according to the battery current and an open circuit voltage curve; predicting a battery terminal voltage according to the current battery open circuit voltage, a current prediction step and a prediction direction to obtain a terminal voltage prediction value; and determining a battery discharge depth extreme value according to the terminal voltage prediction value and the open circuit voltage curve to calculate a remaining state of charge of the battery. The scheme can continuously estimate the remaining state of charge of the battery by only twice table lookup, and has a small amount of calculation.

Description

Technical Field

[0001] This invention belongs to the field of battery management technology, and specifically relates to a method, device and electronic equipment for estimating the state of charge of a battery. Background Technology

[0002] In a battery management system, accurate estimation of the battery's state of charge can effectively prevent overcharging and over-discharging, thereby reducing battery aging problems caused by abnormal use.

[0003] Currently, lithium battery state-of-charge (SOC) estimation methods include the ampere-hour integral method, open-circuit voltage method, ampere-hour integral-open-circuit voltage method, Kalman filter method, and observer method. Among these, the observer method suffers from observation stability issues; the Kalman filter method involves large computational loads and numerous tuning parameters, making it difficult to integrate into dedicated battery management chips; the ampere-hour integral-open-circuit voltage method combines the advantages of both methods and has been widely used in various battery management systems. However, compared to schemes like the Kalman filter method and the observer method, the ampere-hour integral-open-circuit voltage method itself cannot continuously estimate the SOC under all operating conditions. Current improved ampere-hour integral-open-circuit voltage methods use a search method to achieve continuous SOC estimation, but due to the large number of search iterations and the need for interpolation lookups in the battery open-circuit voltage curve table for each iteration, the computation time is excessive, significantly increasing system power consumption for most battery management systems. Summary of the Invention

[0004] The purpose of the embodiments in this specification is to provide a method, apparatus, and electronic device for estimating the state of charge of a battery.

[0005] To solve the above-mentioned technical problems, the embodiments of this application are implemented in the following ways:

[0006] In a first aspect, this application provides a method for estimating the state of charge of a battery, the method comprising:

[0007] Obtain battery current;

[0008] Determine the current battery open-circuit voltage at the current moment based on the battery current and open-circuit voltage curves.

[0009] Based on the current battery open-circuit voltage, the current prediction step size, and the prediction direction, the battery terminal voltage is predicted to obtain the predicted terminal voltage value.

[0010] Based on the predicted terminal voltage and open-circuit voltage curve, the extreme value of the battery discharge depth is determined in order to calculate the battery's remaining state of charge.

[0011] In one embodiment, determining the current battery open-circuit voltage at the current moment based on the battery current and open-circuit voltage curve includes:

[0012] Obtain the total battery capacity corresponding to the previous battery discharge depth and open circuit voltage curve at the last resting time.

[0013] Determine the current battery discharge depth at the current moment based on the battery current, the previous battery discharge depth, and the total battery capacity.

[0014] Query the open-circuit voltage curve to determine the current battery open-circuit voltage corresponding to the current battery discharge depth.

[0015] In one embodiment, the battery terminal voltage is predicted based on the current battery open-circuit voltage, the current prediction step size, and the prediction direction to obtain a predicted terminal voltage value, including:

[0016] The predicted value of the first terminal voltage is determined based on the current battery open-circuit voltage, the current prediction step size, and the prediction direction.

[0017] When the absolute value of the difference between the first predicted terminal voltage value and the extreme terminal voltage value does not meet the preset condition, the prediction step size and prediction direction of the next step are adjusted, and the first predicted terminal voltage value is determined according to the current battery open circuit voltage and the current prediction step size and prediction direction until the absolute value of the difference between the first predicted terminal voltage value and the extreme terminal voltage value meets the preset condition; the first predicted terminal voltage value corresponding to the condition meeting the preset condition is taken as the final predicted terminal voltage value.

[0018] In one embodiment, the extreme value of the terminal voltage is the minimum value of the terminal voltage;

[0019] When the absolute value of the difference between the first predicted terminal voltage value and the extreme terminal voltage value does not meet the preset condition, adjust the prediction step size and prediction direction for the next step, including:

[0020] Obtain the maximum depth of discharge in the open-circuit voltage curve and determine the first battery open-circuit voltage corresponding to the maximum depth of discharge;

[0021] If Vp-Vpmin>0

[0022] The direction of the next forecast remains unchanged;

[0023] The second battery open-circuit voltage corresponding to the first terminal voltage prediction value is taken as the current battery open-circuit voltage;

[0024] Based on the current battery open-circuit voltage and the first battery open-circuit voltage, determine the prediction step size for the next step;

[0025] If Vp-Vpmin≤0

[0026] The predicted direction for the next step has changed to the opposite direction;

[0027] The second battery open-circuit voltage corresponding to the first terminal voltage prediction value is taken as the first battery open-circuit voltage.

[0028] Based on the current battery open-circuit voltage and the first battery open-circuit voltage, determine the prediction step size for the next step.

[0029] In one embodiment, the extreme value of the battery discharge depth is the first discharge depth;

[0030] Based on the predicted terminal voltage and open-circuit voltage curve, determine the extreme values ​​of battery discharge depth, including:

[0031] Obtain the second open-circuit voltage extreme value corresponding to the final predicted terminal voltage value;

[0032] Based on the open-circuit voltage curve, the first depth of discharge corresponding to the second open-circuit voltage extreme value is obtained.

[0033] In one embodiment, the extreme value of the terminal voltage is the maximum value of the terminal voltage;

[0034] When the absolute value of the difference between the first predicted terminal voltage value and the extreme terminal voltage value does not meet the preset condition, adjust the prediction step size and prediction direction for the next step, including:

[0035] Obtain the minimum discharge depth in the open-circuit voltage curve and determine the open-circuit voltage V0 of the third battery corresponding to the minimum discharge depth;

[0036] If Vp - Vpmax > 0

[0037] The direction of the next forecast remains unchanged;

[0038] The open-circuit voltage of the second battery corresponding to the predicted value of the first terminal voltage is taken as the open-circuit voltage of the third battery.

[0039] Based on the current open-circuit voltage of the battery and the open-circuit voltage of the third battery, determine the prediction step size for the next step;

[0040] If Vp - Vpmax ≤ 0

[0041] The predicted direction for the next step has changed to the opposite direction;

[0042] The second battery open-circuit voltage corresponding to the first terminal voltage prediction value is taken as the current battery open-circuit voltage;

[0043] Based on the current open-circuit voltage of the battery and the open-circuit voltage of the third battery, determine the prediction step size for the next step.

[0044] In one embodiment, the extreme depth of battery discharge includes a second depth of discharge;

[0045] Based on the predicted terminal voltage and open-circuit voltage curve, determine the extreme values ​​of battery discharge depth, including:

[0046] Obtain the first open-circuit voltage extreme value corresponding to the final predicted terminal voltage value;

[0047] Based on the open-circuit voltage curve, the second depth of discharge corresponding to the first open-circuit voltage extreme value is obtained.

[0048] In one embodiment, the extreme values ​​of battery discharge depth include a first discharge depth and a second discharge depth;

[0049] Calculate the remaining state of charge of the battery, including:

[0050] Determine the current battery discharge depth at the current moment based on the battery current and open-circuit voltage curves.

[0051] The remaining state of charge is determined based on the current depth of battery discharge, the first depth of discharge, and the second depth of discharge.

[0052] Secondly, this application provides a battery state of charge estimation device, the device comprising:

[0053] The acquisition module is used to acquire battery current;

[0054] The open-circuit voltage determination module is used to determine the current battery open-circuit voltage at the current moment based on the battery current and open-circuit voltage curves.

[0055] The terminal voltage prediction module is used to predict the battery terminal voltage based on the current battery open-circuit voltage, the current prediction step size, and the prediction direction, and obtain the predicted terminal voltage value.

[0056] The depth of discharge extreme value determination module is used to determine the extreme value of battery discharge based on the predicted terminal voltage value and open circuit voltage curve, so as to calculate the remaining state of charge of the battery.

[0057] Thirdly, this application provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the battery state-of-charge estimation method as described in the first aspect.

[0058] As can be seen from the technical solutions provided in the embodiments of this specification above, this solution: the current battery open-circuit voltage can be obtained by looking up a table based on the open-circuit voltage curve, then the battery terminal voltage is predicted based on the current battery open-circuit voltage, and then the extreme value of the battery discharge depth can be obtained by looking up a table based on the predicted terminal voltage value and the open-circuit voltage curve. Finally, the remaining state of charge of the battery is calculated based on the extreme value of the battery discharge depth. This solution can continuously estimate the remaining state of charge of the battery by looking up a table twice, and the amount of calculation is small. In addition, the estimation of the battery state of charge does not depend on parameters such as the battery design capacity. Therefore, its estimation result is less affected by battery aging. Attached Figure Description

[0059] To more clearly illustrate the technical solutions in the embodiments or prior art of this specification, the drawings used in the description of the embodiments or prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this specification. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0060] Figure 1 A flowchart illustrating the battery state-of-charge estimation method provided in this application;

[0061] Figure 2 A schematic diagram of the first depth of discharge (DODmax) in the battery open-circuit voltage curve provided in this application;

[0062] Figure 3 A schematic diagram of the second depth of discharge (DODmin) in the battery open-circuit voltage curve provided in this application;

[0063] Figure 4 A flowchart for updating the first discharge depth DODmax provided in this application;

[0064] Figure 5 A flowchart for updating the second discharge depth DODmin provided in this application;

[0065] Figure 6 A schematic diagram of the battery state-of-charge estimation device provided in this application;

[0066] Figure 7 A schematic diagram of the structure of the electronic device provided in this application. Detailed Implementation

[0067] To enable those skilled in the art to better understand the technical solutions in this specification, the technical solutions in the embodiments of this specification will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this specification, and not all embodiments. Based on the embodiments in this specification, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this specification.

[0068] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application may also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods have been omitted so as not to obscure the description of this application with unnecessary detail.

[0069] Various modifications and variations can be made to the specific embodiments described in this application without departing from the scope or spirit of this application, as will be apparent to those skilled in the art. Other embodiments derived from this application will be obvious to those skilled in the art. This application specification and embodiments are merely exemplary.

[0070] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0071] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0072] Reference Figure 1 The diagram illustrates a flowchart applicable to the battery state-of-charge estimation method provided in the embodiments of this application. It is understood that this method can be applied to battery management systems in various fields, such as digital devices, mobile phones, power banks, laptops, handling robots, automated guided vehicles, industrial drones, power tools, electric vehicles, electric forklifts, electric motorcycles, electric bicycles, electric toys, medical devices, uninterruptible power supplies, new energy battery storage systems, security equipment, surveying and mapping equipment, and portable devices.

[0073] like Figure 1 As shown, the battery state-of-charge estimation method may include:

[0074] S110, Obtain battery current.

[0075] Specifically, the battery current I flowing through the battery can be sampled in real time. When sampling the battery current I, a data acquisition device that can acquire analog signals in real time can be selected, such as a data acquisition card or analog-to-digital converter (ADC) for acquiring analog signals. Understandably, when sampling the battery current in real time, the sampling rate of the data acquisition device can be set according to actual needs.

[0076] S120. Determine the current battery open-circuit voltage at the current moment based on the battery current and open-circuit voltage curves.

[0077] Specifically, the open-circuit voltage curve is a curve that represents the relationship between the battery's depth of discharge and its open-circuit voltage. The open-circuit voltage curve can be obtained in advance through offline calibration experiments.

[0078] In one embodiment of this application, S120, based on the battery current and open-circuit voltage curves, determines the current battery open-circuit voltage at the current moment, which may include:

[0079] Obtain the total battery capacity corresponding to the previous battery discharge depth and open circuit voltage curve at the last resting time.

[0080] Determine the current battery discharge depth at the current moment based on the battery current, the previous battery discharge depth, and the total battery capacity.

[0081] Query the open-circuit voltage curve to determine the current battery open-circuit voltage corresponding to the current battery discharge depth.

[0082] Specifically, the total battery capacity is the total battery capacity corresponding to the open-circuit voltage curve determined during the offline calibration experiment.

[0083] For example, based on the battery current, the previous battery discharge depth, and the total battery capacity, the current battery discharge depth DODcur is determined as follows:

[0084]

[0085] Where DODlast is the previous battery discharge depth at the previous resting time, tlast is the update time of the previous battery discharge depth, tnow is the current time, I is the battery current, and Qm is the total battery capacity.

[0086] The current battery open-circuit voltage Vcur, corresponding to the current battery discharge depth DODcur, is obtained by querying the battery open-circuit voltage curve and calculating it using equation (1).

[0087] The initial value of the battery discharge depth can be determined by obtaining the terminal voltage at the first resting moment of the battery. Specifically, the terminal voltage at the first resting moment of the battery is obtained and used as the battery open circuit voltage. The battery discharge depth at this moment is obtained by querying the open circuit voltage curve, which is the initial value of the battery discharge depth.

[0088] S130. Based on the current battery open-circuit voltage and the current prediction step size and prediction direction, predict the battery terminal voltage to obtain the predicted terminal voltage value.

[0089] Specifically, the battery terminal voltage can be predicted using the battery's equivalent circuit model. This equivalent circuit model includes equivalent internal resistance models, first-order RC equivalent circuit models, higher-order RC equivalent circuit models, electrochemical cell models, etc., and is not limited here.

[0090] For example, the equivalent internal resistance model of a battery is shown in equation (2):

[0091] V 端 =V(DOD,V)-I*R (2)

[0092] Among them, V 端 R represents the battery terminal voltage, R represents the battery equivalent internal resistance, and I represents the battery current; V(DOD,V) represents the battery open-circuit voltage V corresponding to the current battery discharge depth DOD in the battery open-circuit voltage curve.

[0093] According to equation (2), when the battery open-circuit voltage V, battery current I, and equivalent internal resistance R at the current moment are known, the battery terminal voltage V at the current moment can be calculated. 端 .

[0094] For example, the first-order RC equivalent circuit model is shown in equations (3) and (4):

[0095]

[0096] V 端 =V(DOD,V)-I*R-V1 (4)

[0097] Where R1 represents the polarization resistance caused by electrochemical polarization and concentration polarization inside the battery, C1 represents the capacitive reactance generated during the polarization process, V1 represents the voltage drop caused by the polarization impedance, and V 端 R represents the battery terminal voltage, R represents the battery equivalent internal resistance, and I represents the battery current; V(DOD,V) represents the battery open-circuit voltage V corresponding to the current battery discharge depth DOD in the battery open-circuit voltage curve.

[0098] According to equations (3) and (4), when the battery open-circuit voltage V, battery current I, equivalent internal resistance R, polarization internal resistance R1, and capacitive reactance C1 at the current moment are known, the battery terminal voltage V at the current moment can be calculated. 端 .

[0099] According to equations (2) and (4), the battery terminal voltage can be predicted by directly changing the battery open-circuit voltage.

[0100] In one embodiment of this application, S130 predicts the battery terminal voltage based on the current battery open-circuit voltage, the current prediction step size, and the prediction direction to obtain a predicted terminal voltage value, which may include:

[0101] The predicted value of the first terminal voltage is determined based on the current battery open-circuit voltage, the current prediction step size, and the prediction direction.

[0102] When the absolute value of the difference between the first predicted terminal voltage value and the extreme terminal voltage value does not meet the preset condition, the prediction step size and prediction direction of the next step are adjusted, and the first predicted terminal voltage value is determined according to the current battery open circuit voltage and the current prediction step size and prediction direction until the absolute value of the difference between the first predicted terminal voltage value and the extreme terminal voltage value meets the preset condition; the first predicted terminal voltage value corresponding to the condition meeting the preset condition is taken as the final predicted terminal voltage value.

[0103] Understandably, to ensure the battery open-circuit voltage curve covers overcharge and over-discharge conditions, the total battery capacity Qm corresponding to the open-circuit voltage curve will be greater than the actual designed battery capacity. Users typically determine whether the battery is fully charged or discharged based on the extreme values ​​of the battery terminal voltage. Therefore, the actual battery capacity is the capacity corresponding to the period between the maximum terminal voltage Vpmax and the minimum terminal voltage Vpmin. It is also understandable that the maximum and minimum terminal voltages Vpmax and Vpmin represent the maximum and minimum usable terminal voltages of the current battery, respectively, and can be set according to actual needs. The extreme values ​​of the battery open-circuit voltage corresponding to the maximum and minimum terminal voltages Vpmax and Vpmin are defined as the first extreme value Vmax and the second extreme value Vmin, respectively.

[0104] For example, if the equivalent circuit model is an equivalent internal resistance model, the prediction equation for the first terminal voltage prediction value Vp is determined according to the current battery open-circuit voltage, the current prediction step size, and the prediction direction, as shown in formula (5):

[0105] Vp=(V+N*D)-I*R (5)

[0106] Where N is the prediction step size and D is the prediction direction, which includes an increasing direction and a decreasing direction. The D value corresponding to the increasing and decreasing directions can be set according to actual needs. For example, D is 1 when the prediction direction is increasing and -1 when the prediction direction is decreasing.

[0107] If the equivalent circuit model is a first-order RC equivalent circuit model, the prediction equation for the first terminal voltage prediction value Vp is determined according to the current battery open-circuit voltage, the current prediction step size, and the prediction direction, as shown in formula (6):

[0108] Vp=(V+N*D)-I*R-V1 (6)

[0109] It is understandable that V1 in equation (6) can be estimated and determined based on equations (3) and (4).

[0110] The preset conditions can be set according to actual needs. For example, the preset condition can be less than or equal to a preset value. The preset value can also be set according to actual needs. For example, the preset value Vs is twice the system voltage sampling accuracy.

[0111] The absolute value of the difference between the first predicted terminal voltage value and the extreme terminal voltage value does not meet the preset condition, namely: |Vp-Vpm|>Vs, where the extreme terminal voltage value Vpm includes the maximum terminal voltage value Vpmax and the minimum terminal voltage value Vpmin. At this point, the prediction step size and prediction direction are adjusted for the next step. Based on the adjusted prediction step size and prediction direction, the battery terminal voltage is predicted again until the absolute value of the difference between the first predicted terminal voltage value and the extreme terminal voltage value meets the preset condition |Vp-Vpm|≤Vs. The first predicted terminal voltage value obtained at this point is taken as the final predicted terminal voltage value.

[0112] The following sections calculate the prediction step size and prediction direction for the cases where the terminal voltage extremes are the maximum and minimum values, respectively.

[0113] like Figure 2 and Figure 3 The figures shown are schematic diagrams of the first depth of discharge (DODmax) and the second depth of discharge (DODmin) in the battery open-circuit voltage curve, respectively. Figure 2 and Figure 3 It can be seen that in the battery open-circuit voltage curve, the battery open-circuit voltage and the battery depth of discharge are inversely proportional. Let the minimum depth of discharge in the battery open-circuit voltage curve be 0, and the maximum depth of discharge be DODfull. The corresponding battery open-circuit voltages are V0 and the first battery open-circuit voltage Vfull, respectively. Let the first open-circuit voltage extreme value Vmax and the second open-circuit voltage extreme value Vmin in the battery open-circuit voltage curve correspond to the second depth of discharge DODmin and the first depth of discharge DODmax, respectively.

[0114] In one embodiment of this application, the extreme value of the terminal voltage is the minimum value of the terminal voltage;

[0115] When the absolute value of the difference between the first predicted terminal voltage value and the extreme terminal voltage value does not meet the preset condition, adjust the prediction step size and prediction direction for the next step, including:

[0116] Obtain the maximum depth of discharge in the open-circuit voltage curve and determine the first battery open-circuit voltage corresponding to the maximum depth of discharge;

[0117] If Vp-Vpmin>0

[0118] The direction of the next forecast remains unchanged;

[0119] The second battery open-circuit voltage corresponding to the first terminal voltage prediction value is taken as the current battery open-circuit voltage;

[0120] Based on the current battery open-circuit voltage and the first battery open-circuit voltage, determine the prediction step size for the next step;

[0121] If Vp-Vpmin≤0

[0122] The predicted direction for the next step has changed to the opposite direction;

[0123] The second battery open-circuit voltage corresponding to the first terminal voltage prediction value is taken as the first battery open-circuit voltage.

[0124] Based on the current battery open-circuit voltage and the first battery open-circuit voltage, determine the prediction step size for the next step.

[0125] Specifically, the maximum depth of discharge (DODfull) and the corresponding first battery open-circuit voltage (Vfull) are obtained from the open-circuit voltage curve.

[0126] The predicted first terminal voltage value Vp is compared with the terminal voltage minimum value Vpmin in the above steps to determine whether the prediction direction has changed in the next step, and the prediction step size is adjusted accordingly. Specifically:

[0127] Assume the initial prediction direction is decreasing;

[0128] If Vp-Vpmin>0, the prediction direction for the next step remains unchanged, i.e., it is still a decreasing direction.

[0129] The prediction step size N = (Vcur - Vfull) / 2, where the current battery open-circuit voltage Vcur is updated to the second battery open-circuit voltage corresponding to the current predicted value of the first terminal voltage, and Vfull is the first battery open-circuit voltage corresponding to the maximum discharge depth DODfull in the open-circuit voltage curve.

[0130] If Vp-Vpmin≤0, the prediction direction for the next step changes, becoming an increasing direction.

[0131] The prediction step size N = (Vcur - Vfull) / 2, where the first battery open-circuit voltage Vfull is updated to the second battery open-circuit voltage corresponding to the current predicted value of the first terminal voltage, and Vcur is the current battery open-circuit voltage.

[0132] Based on the predicted terminal voltage and the open-circuit voltage curve, the extreme value of the battery discharge depth is determined. Based on the above embodiment, the determined extreme value of the battery discharge depth is the first discharge depth DODmax, specifically:

[0133] Obtain the second open-circuit voltage extreme value corresponding to the final predicted terminal voltage value;

[0134] Based on the open-circuit voltage curve, the first depth of discharge corresponding to the second open-circuit voltage extreme value is obtained.

[0135] Specifically, when the predicted terminal voltage value is close enough to the terminal voltage minimum value Vpmin, the current battery open-circuit voltage value is defined as the second open-circuit voltage extreme value Vmin; based on the battery open-circuit voltage curve, the first discharge depth DODmax corresponding to the second open-circuit voltage extreme value Vmin can be obtained.

[0136] In one embodiment of this application, the extreme value of the terminal voltage is the maximum value of the terminal voltage;

[0137] When the absolute value of the difference between the first predicted terminal voltage value and the extreme terminal voltage value does not meet the preset condition, adjust the prediction step size and prediction direction for the next step, including:

[0138] Obtain the minimum discharge depth in the open-circuit voltage curve and determine the open-circuit voltage V0 of the third battery corresponding to the minimum discharge depth;

[0139] If Vp - Vpmax > 0

[0140] The direction of the next forecast remains unchanged;

[0141] The open-circuit voltage of the second battery corresponding to the predicted value of the first terminal voltage is taken as the open-circuit voltage of the third battery.

[0142] Based on the current open-circuit voltage of the battery and the open-circuit voltage of the third battery, determine the prediction step size for the next step;

[0143] If Vp - Vpmax ≤ 0

[0144] The predicted direction for the next step has changed to the opposite direction;

[0145] The second battery open-circuit voltage corresponding to the first terminal voltage prediction value is taken as the current battery open-circuit voltage;

[0146] Based on the current open-circuit voltage of the battery and the open-circuit voltage of the third battery, determine the prediction step size for the next step.

[0147] Specifically, obtain the minimum discharge depth 0 and the corresponding open-circuit voltage V0 of the third battery from the open-circuit voltage curve.

[0148] The predicted first terminal voltage value Vp is compared with the terminal voltage maximum value Vpmax in the above steps to determine whether the prediction direction for the next step has changed, and the prediction step size is adjusted accordingly. Specifically:

[0149] Assume the initial prediction direction is decreasing;

[0150] If Vp-Vpmax>0, the prediction direction for the next step remains unchanged, i.e., it is still a decreasing direction.

[0151] The prediction step size N = (V0 - Vcur) / 2, where the open-circuit voltage V0 of the third battery is updated to the open-circuit voltage of the second battery corresponding to the predicted value Vp of the first terminal voltage, and Vcur is the current open-circuit voltage of the battery.

[0152] If Vp-Vpmin≤0, the prediction direction for the next step changes, becoming an increasing direction.

[0153] The prediction step size N = (V0 - Vcur) / 2, where the current battery open-circuit voltage Vcur is updated to the second battery open-circuit voltage corresponding to the current predicted value of the first terminal voltage, and V0 is the third battery open-circuit voltage corresponding to the minimum discharge depth 0 in the open-circuit voltage curve.

[0154] Based on the predicted terminal voltage and open-circuit voltage curve, the extreme value of battery discharge depth is determined. Building upon the above embodiment, the determined extreme value of battery discharge depth is the second discharge depth DODmin, specifically:

[0155] Obtain the first open-circuit voltage extreme value Vmax corresponding to the final predicted terminal voltage value;

[0156] Based on the open-circuit voltage curve, the second discharge depth DODmin corresponding to the first open-circuit voltage extreme value is obtained.

[0157] Specifically, when the predicted terminal voltage value is close enough to the maximum terminal voltage value Vpmax, the current battery open-circuit voltage value is defined as the first open-circuit voltage extreme value Vmax; based on the battery open-circuit voltage curve, the second discharge depth DODmin corresponding to the first open-circuit voltage extreme value Vmax can be obtained.

[0158] It is understood that the prediction process for the terminal voltages involved in the two battery discharge depths (including the first discharge depth and the second discharge depth) in the above two embodiments can be carried out independently and without affecting each other, that is, the two prediction processes can be processed in parallel.

[0159] Example

[0160] Figure 4 This is a flowchart showing the update process for the first discharge depth DODmax.

[0161] like Figure 4 As shown, the steps to determine the first discharge depth DODmax are as follows:

[0162] Step 11: Obtain the current battery open circuit voltage Vcur and the first battery open circuit voltage Vfull corresponding to the current battery discharge depth DODcur and the maximum discharge depth DODfull based on the open circuit voltage curve.

[0163] Step 12: Set the battery terminal voltage prediction target as the terminal voltage minimum value Vpmin.

[0164] Step 13: Set the initial prediction direction to a decreasing direction (i.e., decreasing prediction), and set the initial prediction step size to N equal to (Vcur-Vfull) / 2.

[0165] Step 14: Using the equivalent circuit model, combined with the prediction step size and prediction direction, predict the battery terminal voltage to obtain the first predicted terminal voltage value Vp.

[0166] Step 15: Determine if |Vp-Vpmin|≤Vs is true. If not, proceed to step 16; if true, proceed to step 17.

[0167] Step 16: Determine if Vp-Vpmin>0 is true. If true, update the prediction direction to decreasing prediction, then update the current battery open-circuit voltage Vcur to the open-circuit voltage corresponding to the current predicted first terminal voltage value Vp, and simultaneously update the prediction step size N=(Vcur-Vfull) / 2, then return to step 14. If false, update the prediction direction to increasing prediction, then update the first battery open-circuit voltage Vfull to the open-circuit voltage corresponding to the current predicted first terminal voltage value Vp, and simultaneously update the prediction step size N=(Vcur-Vfull) / 2, then return to step 14.

[0168] Step 17: Obtain the second open-circuit voltage extreme value Vmin corresponding to the final predicted terminal voltage value Vp.

[0169] Step 18: Use the battery open-circuit voltage curve to interpolate the second open-circuit voltage extreme value Vmin to obtain the corresponding first discharge depth DODmax.

[0170] Figure 5 The flowchart shows the update process for the second discharge depth DODmin.

[0171] like Figure 5 As shown, the steps for determining the second discharge depth DODmin are as follows:

[0172] Step 21: Obtain the third battery open-circuit voltage V0 and the current battery open-circuit voltage Vcur corresponding to the minimum discharge depth 0 and the current battery discharge depth DODcur based on the open-circuit voltage curve.

[0173] Step 22: Set the target for predicting the battery terminal voltage as the maximum terminal voltage value Vpmax.

[0174] Step 23: Set the initial prediction direction to a decreasing direction (i.e., decreasing prediction), and set the initial prediction step size to N equal to (V0-Vcur) / 2.

[0175] Step 24: Using the equivalent circuit model, combined with the prediction step size and prediction direction, predict the battery terminal voltage to obtain the first predicted terminal voltage value Vp.

[0176] Step 25: Determine whether |Vp-Vpmax|≤Vs is true. If not, proceed to step 26; if true, proceed to step 27.

[0177] Step 26: Determine whether Vp-Vpmax>0 is true. If true, update the prediction direction to decreasing prediction, then update the open-circuit voltage V0 of the third battery to the open-circuit voltage corresponding to the current predicted first terminal voltage value Vp, and simultaneously update the prediction step size N=(V0-Vcur) / 2, then return to step 24. If false, update the prediction direction to increasing prediction, then update the current battery open-circuit voltage Vcur to the open-circuit voltage corresponding to the current predicted first terminal voltage value Vp, and simultaneously update the prediction step size N=(V0-Vcur) / 2, then return to step 24.

[0178] Step 27: Obtain the first open-circuit voltage extreme value Vmax corresponding to the final predicted terminal voltage value Vp.

[0179] Step 28: Use the battery open-circuit voltage curve to interpolate the first open-circuit voltage extreme value Vmin to obtain the corresponding second discharge depth DODmin.

[0180] Based on the above embodiments, calculating the remaining state of charge of the battery may include:

[0181] Determine the current battery discharge depth at the current moment based on the battery current and open-circuit voltage curves.

[0182] The remaining state of charge is determined based on the current depth of battery discharge, the first depth of discharge, and the second depth of discharge.

[0183] Since the actual battery capacity is the battery capacity corresponding to the period between the maximum terminal voltage Vpmax and the minimum terminal voltage Vpmin, that is, the actual battery capacity is the battery capacity corresponding to the period between the second depth of discharge DODmin and the first depth of discharge DODmax, the remaining state of charge (SOC) of the battery can be calculated by equation (7):

[0184] SOC=(DODmax-DODcur) / (DODmax-DODmin) (7)

[0185] Where DODcur is the current depth of battery discharge.

[0186] The battery state of charge estimation method provided in this application obtains the current battery open-circuit voltage by looking up a table based on the open-circuit voltage curve. Then, the battery terminal voltage is predicted based on the current battery open-circuit voltage. After that, the extreme value of the battery discharge depth is obtained by looking up a table based on the predicted terminal voltage and the open-circuit voltage curve. Finally, the remaining state of charge of the battery is calculated based on the extreme value of the battery discharge depth. This scheme can continuously estimate the remaining state of charge of the battery by looking up two tables, and the amount of calculation is small. In addition, the estimation of the battery state of charge does not depend on parameters such as the battery design capacity. Therefore, its estimation results are less affected by battery aging.

[0187] Reference Figure 6 The diagram illustrates a structural schematic of a battery state-of-charge estimation device according to an embodiment of this application.

[0188] like Figure 6 As shown, the battery state-of-charge estimation device 600 may include:

[0189] The acquisition module 610 is used to acquire the battery current;

[0190] The open-circuit voltage determination module 620 is used to determine the current battery open-circuit voltage at the current moment based on the battery current and open-circuit voltage curves.

[0191] The terminal voltage prediction module 630 is used to predict the battery terminal voltage based on the current battery open-circuit voltage, the current prediction step size, and the prediction direction, and obtain the predicted terminal voltage value.

[0192] The discharge depth extreme value determination module 640 is used to determine the battery discharge depth extreme value based on the terminal voltage prediction value and the open circuit voltage curve, so as to calculate the battery's remaining state of charge.

[0193] Optionally, the open-circuit voltage determination module 620 is also used for:

[0194] Obtain the total battery capacity corresponding to the previous battery discharge depth and open circuit voltage curve at the last resting time.

[0195] Determine the current battery discharge depth at the current moment based on the battery current, the previous battery discharge depth, and the total battery capacity.

[0196] Query the open-circuit voltage curve to determine the current battery open-circuit voltage corresponding to the current battery discharge depth.

[0197] Optionally, the terminal voltage prediction module 630 is also used for:

[0198] The predicted value of the first terminal voltage is determined based on the current battery open-circuit voltage, the current prediction step size, and the prediction direction.

[0199] When the absolute value of the difference between the first predicted terminal voltage value and the extreme terminal voltage value does not meet the preset condition, the prediction step size and prediction direction of the next step are adjusted, and the first predicted terminal voltage value is determined according to the current battery open circuit voltage and the current prediction step size and prediction direction until the absolute value of the difference between the first predicted terminal voltage value and the extreme terminal voltage value meets the preset condition; the first predicted terminal voltage value corresponding to the condition meeting the preset condition is taken as the final predicted terminal voltage value.

[0200] Optionally, if the extreme value of the terminal voltage is the minimum value of the terminal voltage;

[0201] The terminal voltage prediction module 630 is also used for:

[0202] Obtain the maximum depth of discharge in the open-circuit voltage curve and determine the first battery open-circuit voltage corresponding to the maximum depth of discharge;

[0203] If Vp-Vpmin>0

[0204] The direction of the next forecast remains unchanged;

[0205] The second battery open-circuit voltage corresponding to the first terminal voltage prediction value is taken as the current battery open-circuit voltage;

[0206] Based on the current battery open-circuit voltage and the first battery open-circuit voltage, determine the prediction step size for the next step;

[0207] If Vp-Vpmin≤0

[0208] The predicted direction for the next step has changed to the opposite direction;

[0209] The second battery open-circuit voltage corresponding to the first terminal voltage prediction value is taken as the first battery open-circuit voltage.

[0210] Based on the current battery open-circuit voltage and the first battery open-circuit voltage, determine the prediction step size for the next step.

[0211] Optionally, the extreme value of the battery discharge depth is the first discharge depth;

[0212] The depth of discharge extreme value determination module 640 is also used for:

[0213] Obtain the second open-circuit voltage extreme value corresponding to the final predicted terminal voltage value;

[0214] Based on the open-circuit voltage curve, the first depth of discharge corresponding to the second open-circuit voltage extreme value is obtained.

[0215] Optionally, if the extreme value of the terminal voltage is the maximum value of the terminal voltage;

[0216] The terminal voltage prediction module 630 is also used for:

[0217] Obtain the minimum discharge depth in the open-circuit voltage curve and determine the open-circuit voltage V0 of the third battery corresponding to the minimum discharge depth;

[0218] If Vp - Vpmax > 0

[0219] The direction of the next forecast remains unchanged;

[0220] The open-circuit voltage of the second battery corresponding to the predicted value of the first terminal voltage is taken as the open-circuit voltage of the third battery.

[0221] Based on the current open-circuit voltage of the battery and the open-circuit voltage of the third battery, determine the prediction step size for the next step;

[0222] If Vp - Vpmax ≤ 0

[0223] The predicted direction for the next step has changed to the opposite direction;

[0224] The second battery open-circuit voltage corresponding to the first terminal voltage prediction value is taken as the current battery open-circuit voltage;

[0225] Based on the current open-circuit voltage of the battery and the open-circuit voltage of the third battery, determine the prediction step size for the next step.

[0226] Optionally, the extreme depth of battery discharge includes a second depth of discharge;

[0227] The depth of discharge extreme value determination module 640 is also used for:

[0228] Obtain the first open-circuit voltage extreme value corresponding to the final predicted terminal voltage value;

[0229] Based on the open-circuit voltage curve, the second depth of discharge corresponding to the first open-circuit voltage extreme value is obtained.

[0230] Optionally, the extreme values ​​of battery discharge depth include a first discharge depth and a second discharge depth;

[0231] The battery state of charge estimation device also includes a calculation module for:

[0232] Determine the current battery discharge depth at the current moment based on the battery current and open-circuit voltage curves.

[0233] The remaining state of charge is determined based on the current depth of battery discharge, the first depth of discharge, and the second depth of discharge.

[0234] The battery state of charge estimation device provided in this embodiment can perform the above-described method, and its implementation principle and technical effect are similar, so they will not be described again here.

[0235] Figure 7 This is a schematic diagram of the structure of an electronic device provided in an embodiment of the present invention. Figure 7 The diagram shows a structural schematic of an electronic device 700 suitable for implementing embodiments of this application.

[0236] like Figure 7 As shown, the electronic device 700 includes a central processing unit (CPU) 701, which can perform various appropriate actions and processes according to a program stored in a read-only memory (ROM) 702 or a program loaded from a storage section 708 into a random access memory (RAM) 703. The RAM 703 also stores various programs and data required for the operation of the device 700. The CPU 701, ROM 702, and RAM 703 are interconnected via a bus 704. An input / output (I / O) interface 705 is also connected to the bus 704.

[0237] The following components are connected to I / O interface 705: an input section 706 including a keyboard, mouse, etc.; an output section 707 including a cathode ray tube (CRT), liquid crystal display (LCD), etc., and speakers, etc.; a storage section 708 including a hard disk, etc.; and a communication section 709 including a network interface card such as a LAN card, modem, etc. The communication section 709 performs communication processing via a network such as the Internet. A drive 710 is also connected to I / O interface 706 as needed. A removable medium 711, such as a disk, optical disk, magneto-optical disk, semiconductor memory, etc., is installed on drive 710 as needed so that computer programs read from it can be installed into storage section 708 as needed.

[0238] In particular, according to embodiments of this disclosure, the above references Figure 1The described process can be implemented as a computer software program. For example, embodiments of this disclosure include a computer program product comprising a computer program tangibly embodied on a machine-readable medium, the computer program containing program code for performing the battery state-of-charge estimation method described above. In such embodiments, the computer program can be downloaded and installed from a network via communication section 709, and / or installed from removable medium 711.

[0239] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of the present invention. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those indicated in the drawings. For example, two consecutively indicated blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, can be implemented using a dedicated hardware-based system that performs the specified function or operation, or using a combination of dedicated hardware and computer instructions.

[0240] The units or modules described in the embodiments of this application can be implemented in software or hardware. The described units or modules can also be located in a processor. The names of these units or modules do not necessarily constitute a limitation on the unit or module itself.

[0241] The systems, devices, modules, or units described in the above embodiments can be implemented by computer chips or entities, or by products with certain functions. A typical implementation device is a computer. Specifically, a computer can be, for example, a personal computer, a laptop computer, a mobile phone, a smartphone, a personal digital assistant, a media player, a navigation device, an email device, a game console, a tablet computer, a wearable device, or any combination of these devices.

[0242] It should be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0243] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to interchangeably. Each embodiment focuses on describing the differences from other embodiments. In particular, the system embodiments are basically similar to the method embodiments, so the description is relatively simple; relevant parts can be referred to the descriptions in the method embodiments.

Claims

1. A method for estimating the state of charge of a battery, characterized in that, The method includes: Obtain battery current; Based on the battery current and open-circuit voltage curves, determine the current battery open-circuit voltage and current battery discharge depth at the current moment. Based on the current battery open-circuit voltage, the current prediction step size, and the prediction direction, a first terminal voltage prediction value is determined. When the absolute value of the difference between the first terminal voltage prediction value and the terminal voltage extreme value does not meet a preset condition, the prediction step size and prediction direction for the next step are adjusted, and the first terminal voltage prediction value is determined again based on the current battery open-circuit voltage, the current prediction step size, and the prediction direction, until the absolute value of the difference between the first terminal voltage prediction value and the terminal voltage extreme value meets the preset condition. The first terminal voltage prediction value corresponding to meeting the preset condition is taken as the final terminal voltage prediction value. The preset condition is less than or equal to a preset value. The terminal voltage extreme value includes the terminal voltage maximum value and / or the terminal voltage minimum value. Obtain the extreme values ​​of the battery open-circuit voltage corresponding to the final predicted terminal voltage value, wherein the extreme values ​​of the battery open-circuit voltage corresponding to the maximum and minimum terminal voltage values ​​are the first extreme value and the second extreme value, respectively. Based on the open-circuit voltage curve, the extreme value of battery discharge depth corresponding to the extreme value of battery open-circuit voltage is obtained. The extreme value of battery discharge depth corresponds to the first discharge depth when the battery open-circuit voltage is the second extreme value of open-circuit voltage, and corresponds to the second discharge depth when the battery open-circuit voltage is the first extreme value of open-circuit voltage. The remaining state of charge is determined based on the current battery discharge depth and the extreme value of the battery discharge depth.

2. The method according to claim 1, characterized in that, Determining the current battery open-circuit voltage at the current moment based on the battery current and open-circuit voltage curves includes: Obtain the previous battery discharge depth and the total battery capacity corresponding to the open circuit voltage curve at the previous resting time. The current battery discharge depth is determined based on the battery current, the previous battery discharge depth, and the total battery capacity. The open-circuit voltage curve is used to determine the current battery open-circuit voltage corresponding to the current battery discharge depth.

3. The method according to claim 1, characterized in that, If the extreme value of the terminal voltage is the minimum value of the terminal voltage; When the absolute value of the difference between the first predicted terminal voltage value and the extreme value of the terminal voltage does not meet the preset condition, adjusting the prediction step size and prediction direction for the next step includes: Obtain the maximum depth of discharge in the open-circuit voltage curve, and determine the first battery open-circuit voltage corresponding to the maximum depth of discharge; If Vp-Vpmin>0, Vp is the first predicted terminal voltage value, and Vpmin is the minimum terminal voltage value; The direction of the next forecast remains unchanged; The second battery open-circuit voltage corresponding to the first terminal voltage prediction value is taken as the current battery open-circuit voltage; Based on the current battery open-circuit voltage and the first battery open-circuit voltage, determine the prediction step size for the next step; If Vp-Vpmin≤0 The predicted direction for the next step has changed to the opposite direction; The second battery open-circuit voltage corresponding to the first terminal voltage prediction value is taken as the first battery open-circuit voltage; The prediction step size for the next step is determined based on the current battery open-circuit voltage and the first battery open-circuit voltage.

4. The method according to claim 1, characterized in that, If the extreme value of the terminal voltage is the maximum value of the terminal voltage; When the absolute value of the difference between the first predicted terminal voltage value and the extreme value of the terminal voltage does not meet the preset condition, adjusting the prediction step size and prediction direction for the next step includes: Obtain the minimum discharge depth in the open-circuit voltage curve, and determine the third battery open-circuit voltage V0 corresponding to the minimum discharge depth; If Vp-Vpmax>0, where Vp is the first predicted terminal voltage value and Vpmax is the maximum terminal voltage value; The direction of the next forecast remains unchanged; The second battery open-circuit voltage corresponding to the first terminal voltage prediction value is taken as the third battery open-circuit voltage; Based on the current battery open-circuit voltage and the third battery open-circuit voltage, determine the prediction step size for the next step; If Vp - Vpmax ≤ 0 The predicted direction for the next step has changed to the opposite direction; The second battery open-circuit voltage corresponding to the first terminal voltage prediction value is taken as the current battery open-circuit voltage; The prediction step size for the next step is determined based on the current battery open-circuit voltage and the third battery open-circuit voltage.

5. A battery state of charge estimation device, characterized in that, The device includes: The acquisition module is used to acquire battery current; The open-circuit voltage determination module is used to determine the current battery open-circuit voltage at the current moment based on the battery current and open-circuit voltage curves. A terminal voltage prediction module is used to determine a first predicted terminal voltage value based on the current battery open-circuit voltage, the current prediction step size, and the prediction direction. When the absolute value of the difference between the first predicted terminal voltage value and the terminal voltage extreme value does not meet a preset condition, the module adjusts the prediction step size and prediction direction for the next step and continues to determine the first predicted terminal voltage value based on the current battery open-circuit voltage, the current prediction step size, and the prediction direction until the absolute value of the difference between the first predicted terminal voltage value and the terminal voltage extreme value meets the preset condition. The first predicted terminal voltage value corresponding to meeting the preset condition is taken as the final predicted terminal voltage value. The preset condition is less than or equal to a preset value. The terminal voltage extreme value includes the terminal voltage maximum value and / or the terminal voltage minimum value. The depth of discharge extreme value determination module is used to obtain the battery open-circuit voltage extreme value corresponding to the final predicted terminal voltage value, wherein the battery open-circuit voltage extreme values ​​corresponding to the maximum and minimum terminal voltage values ​​are respectively the first open-circuit voltage extreme value and the second open-circuit voltage extreme value; according to the open-circuit voltage curve, the battery depth of discharge extreme value corresponding to the battery open-circuit voltage extreme value is obtained, wherein the battery depth of discharge extreme value corresponds to the first depth of discharge when the battery open-circuit voltage is the second open-circuit voltage extreme value, and corresponds to the second depth of discharge when the battery open-circuit voltage is the first open-circuit voltage extreme value; according to the battery current and open-circuit voltage curve, the current battery depth of discharge at the current moment is determined; and according to the current battery depth of discharge and the battery depth of discharge extreme value, the remaining state of charge is determined.

6. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the battery state-of-charge estimation method as described in any one of claims 1-4.

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