SOC estimation method, device, electronic device and storage medium with self-adjusting zero point

Abstract

This application provides a self-adjusting zero-point SOC estimation method, device, electronic device, and storage medium. The method includes: obtaining a battery sample value under the current battery operating condition; processing the battery sample value using the ampere-hour integration method and an equivalent circuit model to obtain the battery open-circuit voltage; performing a curve transformation on the battery open-circuit voltage to obtain the battery depth of discharge; and correcting the battery depth of discharge based on the current battery operating condition to obtain the battery state of charge. This application allows the battery state of charge to be smoothly adjusted to zero without jumping.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a method, device, electronic device, and storage medium for self-adjusting zero-point SOC estimation. Background Art

[0002] The battery state of charge (SOC) is an important indicator that characterizes the current available capacity of the battery pack and is also the part that users pay most attention to when using the battery. Obtaining a more accurate, smooth, non-jumpy, and non-sharp SOC estimation curve can greatly optimize the user experience of the product.

[0003] Currently, the SOC estimation method for lithium-ion batteries generally combines ampere-hour integration with open-circuit voltage. However, the calculation process has cumulative errors and cannot identify the end points of charge and discharge, resulting in many phenomena that affect the user experience. For example, the error is very large under certain operating conditions, and the end-of-discharge jump, etc., will cause the SOC estimation curve to be uneven. For example, it may jump directly from 30% to 0, resulting in an uneven SOC estimation curve. Summary of the Invention

[0004] The purpose of the embodiments of the present application is to provide a method, device, electronic device, and storage medium for SOC estimation with self-adjusting zero point to solve the problem of uneven SOC estimation curve. The specific technical solution is as follows:

[0005] In a first aspect, a method for estimating an SOC with a self-adjusting zero point is provided, the method comprising:

[0006] Get the battery sampling value under the current battery working condition;

[0007] Processing the battery sample value by using the ampere-hour integration method and the equivalent circuit model to obtain the battery open circuit voltage;

[0008] Performing curve transformation on the open circuit voltage of the battery to obtain the battery discharge depth;

[0009] The battery discharge depth is corrected according to the current battery operating condition of the battery to obtain the battery state of charge.

[0010] Optionally, the processing the battery sample value by using the ampere-hour integration method and the equivalent circuit model to obtain the battery open circuit voltage includes:

[0011] Calculating and processing the battery sampling value by the ampere-hour integration method to obtain the integrated discharge depth;

[0012] The battery sampling value and the integrated discharge depth are input into an equivalent circuit model to obtain the battery open circuit voltage.

[0013] Optionally, the battery sampling values include sampling voltage, sampling current and sampling temperature;

[0014] The calculating and processing the battery sampling value by the ampere-hour integration method to obtain the integrated discharge depth includes:

[0015] Determining an initial depth of discharge of the battery upon power-on based on the sampled voltage and a preset mapping table;

[0016] Determining a first capacity of current flowing through the battery after power-on based on the sampled current and a preset integration time step;

[0017] Determine a second capacity of the battery released from full charge to empty charge at a set rate at the sampling temperature;

[0018] An integrated depth of discharge is calculated based on the initial depth of discharge, the first capacity, and the second capacity.

[0019] Optionally, the battery sampling values include sampling voltage, sampling current and sampling temperature;

[0020] Inputting the battery sampling value and the integrated discharge depth into an equivalent circuit model to obtain the battery open circuit voltage includes:

[0021] Determining a target DC impedance of the battery according to the integrated discharge depth, the sampling temperature, and a preset parameter table;

[0022] The battery open circuit voltage is calculated according to the sampled voltage, the sampled current and the target DC impedance.

[0023] Optionally, a preset parameter table is obtained; correspondingly, obtaining the preset parameter table includes:

[0024] Charge multiple batteries with constant current and then constant voltage until they are fully charged;

[0025] performing a first operation on a plurality of batteries that have been stationed for preset periods of time at different stationary temperatures at a plurality of different discharge rates to obtain a plurality of reference battery internal resistances of the plurality of batteries at the different stationary temperatures, the first operation comprising: discharging the battery to a cutoff voltage at the discharge rate, obtaining the battery voltage and discharge depth corresponding to each change in the preset depth, and obtaining the reference battery internal resistance based on a preset mapping table, the discharge depth, the battery voltage, and the discharge rate;

[0026] performing a second operation on the multiple reference battery internal resistances to obtain multiple target battery internal resistances at different resting temperatures, the second operation comprising: averaging the multiple reference battery internal resistances obtained by performing the first operation on the multiple batteries at the same resting temperature at different discharge rates to obtain the target battery internal resistance;

[0027] The parameter table is generated according to a plurality of target battery internal resistances, a plurality of corresponding discharge depths, and a plurality of corresponding rest temperatures.

[0028] Optionally, performing curve transformation on the battery open circuit voltage to obtain the battery discharge depth includes:

[0029] Obtaining a static open circuit voltage of the battery when it is discharged to a cut-off voltage under a current battery operating condition, and obtaining a preset open circuit voltage according to a preset mapping table;

[0030] Performing proportional curve transformation on the battery open circuit voltage according to the static open circuit voltage and the preset open circuit voltage to obtain an intermediate open circuit voltage;

[0031] The battery discharge depth is calculated according to the intermediate open circuit voltage and a preset polynomial fitting coefficient result.

[0032] Optionally, obtaining the static open circuit voltage of the battery when discharged to the cut-off voltage under the current battery operating condition includes:

[0033] Get the preset battery undervoltage protection voltage, current current, and battery internal resistance when the battery is discharged;

[0034] Calculate the static open-circuit voltage of the battery after it is discharged to the cutoff voltage under the current battery operating condition according to the battery undervoltage protection voltage, the current current, and the battery internal resistance when the battery is discharged.

[0035] Optionally, the preset open circuit voltage includes a second open circuit voltage obtained by discharging the battery at a preset rate to a cut-off voltage and then allowing the battery to stand, and calculating the battery discharge depth based on the intermediate open circuit voltage and a polynomial fitting coefficient result includes:

[0036] Acquire multiple open circuit voltages corresponding to multiple discharge depths according to the mapping table, and use the multiple open circuit voltages to calculate the variance voltage;

[0037] Obtaining an intermediate value according to the intermediate open circuit voltage, the second open circuit voltage, and the variance voltage;

[0038] The battery discharge depth is obtained by calculation according to the intermediate value and the polynomial fitting coefficient.

[0039] Optionally, the polynomial fitting coefficients are obtained by the following method:

[0040] performing a centering process and a scaling transformation on the open circuit voltage according to the second open circuit voltage and the variance voltage to obtain a transformed voltage;

[0041] A polynomial fitting coefficient result is calculated based on the conversion voltage and the discharge depth.

[0042] In a second aspect, a SOC estimation device with self-adjusting zero point is provided, the device comprising:

[0043] The acquisition module is used to obtain the battery sampling value under the current battery working condition;

[0044] a processing module, configured to process the battery sampling value by using an ampere-hour integration method and an equivalent circuit model to obtain a battery open circuit voltage;

[0045] A conversion module, used to perform curve conversion on the battery open circuit voltage to obtain the battery discharge depth;

[0046] The correction module is used to correct the battery discharge depth according to the current battery operating condition of the battery to obtain the battery state of charge.

[0047] In a third aspect, an electronic device is provided, comprising a controller, a communication interface, a memory, and a communication bus, wherein the controller, the communication interface, and the memory communicate with each other via the communication bus;

[0048] Memory for storing computer programs;

[0049] The controller is used to implement any of the steps of the self-adjusting zero-point SOC estimation method when executing the program stored in the memory.

[0050] In a fourth aspect, a computer-readable storage medium is provided, wherein a computer program is stored in the computer-readable storage medium, and when the computer program is executed by a controller, any of the steps of the self-adjusting zero-point SOC estimation method is implemented.

[0051] Beneficial effects of the embodiments of the present application:

[0052] The present application provides a self-adjusting zero-point SOC estimation method that obtains battery sampling values under the current battery operating conditions, processes the battery sampling values to obtain the battery open-circuit voltage, applies a curve transformation to the battery open-circuit voltage to obtain the battery depth of discharge, and corrects the battery depth of discharge to obtain the battery state of charge. The battery sampling values change in real time based on the operating conditions of the load connected to the battery. Therefore, regardless of the load state (even a negative pressure state), the curve transformation of the battery open-circuit voltage allows the battery state of charge to be smoothly adjusted to zero without jumping.

[0053] Of course, it is not necessary to achieve all of the above advantages at the same time when implementing any product or method of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0055] Figure 1 A flow chart of a method for self-adjusting zero-point SOC estimation provided in an embodiment of the present application;

[0056] Figure 2 A flow chart of a method for obtaining integrated discharge depth provided in an embodiment of the present application;

[0057] Figure 3 A flow chart of a method for obtaining the open circuit voltage of a battery provided in an embodiment of the present application;

[0058] Figure 4 A flow chart of a method for obtaining a battery discharge depth provided in an embodiment of the present application;

[0059] Figure 5 A schematic structural diagram of a SOC estimation device with self-adjusting zero point provided in an embodiment of the present application;

[0060] Figure 6 A schematic diagram of the structure of an electronic device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0061] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0062] In the subsequent description, the suffixes such as "module", "component" or "unit" used to represent elements are only used to facilitate the description of this application and have no specific meaning. Therefore, "module" and "component" can be used interchangeably.

[0063] In order to solve the problems mentioned in the background technology, according to one aspect of an embodiment of the present application, an embodiment of a SOC estimation method with self-adjusting zero point is provided.

[0064] An embodiment of the present application provides a self-adjusting zero-point SOC estimation method, which can be applied to a controller of a smart device to smoothly adjust the battery's SOC to zero in any scenario.

[0065] The following will describe in detail a method for estimating SOC with self-adjusting zero point provided by the embodiment of the present application in conjunction with a specific embodiment. Figure 1 The specific steps are as follows:

[0066] Step 101: Obtain battery sampling values under current battery operating conditions.

[0067] The controller obtains battery sampling values under the current battery operating condition. The current battery operating condition refers to the current voltage, current current and current temperature. Exemplarily, the battery sampling values include the sampled voltage U, the sampled current I and the sampled temperature T.

[0068] Step 102: Process the battery sample value using the ampere-hour integration method and the equivalent circuit model to obtain the battery open circuit voltage.

[0069] The controller first processes the battery sampling value using the ampere-hour integration method to obtain the integrated discharge depth DODah (Depth of Discharge), where the integrated discharge depth refers to the percentage of the actual discharge capacity of the battery to the rated capacity of the battery after the battery releases the first capacity and the second capacity.

[0070] The battery sampling value and the integrated discharge depth are then input into the equivalent circuit model to obtain the battery open circuit voltage (OCVest). The battery open circuit voltage refers to the potential difference between the positive and negative electrodes of the current battery, obtained based on the sampled voltage, sampled current, sampled temperature, and parameter table.

[0071] Step 103: Perform curve transformation on the battery open circuit voltage to obtain the battery discharge depth.

[0072] The controller performs a curve transformation on the battery open circuit voltage to obtain the battery discharge depth DODest, wherein the battery discharge depth is a value obtained by performing a curve transformation on the battery open circuit voltage.

[0073] Step 104: Correct the battery discharge depth based on the current battery operating condition to obtain the battery state of charge.

[0074] The current battery operating condition is used to indicate the current charge and discharge state of the battery, including the charge state and discharge state. The controller corrects the battery discharge depth according to the charge and discharge state (i.e., charge state or discharge state) to obtain the battery state of charge (SOC). The battery state of charge is the ratio of the remaining capacity of the battery after a period of use or long-term storage to its capacity when fully charged.

[0075] In this application, the controller obtains the battery sampling value under the current battery operating condition, processes the battery sampling value to obtain the battery open circuit voltage, performs a curve transformation on the battery open circuit voltage to obtain the battery discharge depth, and corrects the battery discharge depth to obtain the battery state of charge. The battery sampling value can change in real time according to the operating condition of the load connected to the battery. Therefore, regardless of the load state (even in a negative pressure state), due to the curve transformation of the battery open circuit voltage, the battery state of charge can be smoothly adjusted to zero without jumping.

[0076] Compared with the Kalman filtering method used in the prior art, the Kalman filtering method is usually based on first-order, second-order RC (Radio Control) battery models or electrochemical models, etc., and estimates the battery state of charge through real-time monitoring and updating of state equations and observation equations. Although this type of algorithm has high calculation accuracy, the calculation process is complex and requires more processing resources of the controller. This application only needs to obtain battery sampling values and perform calculations on them. The entire calculation process is simple and does not require consuming more processing resources of the controller.

[0077] Compared with the existing technology that uses the neural network method, the neural network method achieves accurate estimation of the battery state of charge by learning a large amount of data and continuously adjusting the weights of neurons between various layers such as the input layer and the hidden layer. This method requires a large amount of data and is related to the accuracy of the training data and the rationality of the model training method. Therefore, it has a greater impact on the accuracy of the battery state of charge estimation. This application only needs to obtain the battery sampling value and perform calculation processing on it. The amount of data required is small, and it is not affected by the training data, and the accuracy is high.

[0078] In addition, the Kalman filter algorithm and the neural network method require a large number of retests to match the model when only the battery is replaced or the combination is changed. For smart hardware products such as sweepers, floor scrubbers, and service robots, the R&D cost is high and the cycle is long. The self-adjusting zero-point SOC estimation method proposed in this application has a simple calculation method and low resource cost. At the same time, the battery state of charge estimation accuracy is high, and the battery state of charge can be smoothly adjusted to zero through the smooth curve after transformation, and self-adjusting zero point can be achieved. It is suitable for use scenarios such as small batteries for smart hardware.

[0079] As an optional implementation, Figure 2 As shown, the battery sampling values include sampling voltage, sampling current and sampling temperature. The battery sampling values are calculated and processed by the ampere-hour integration method to obtain the integrated discharge depth, which includes:

[0080] Step 201: Determine the initial depth of discharge of the battery when powered on according to the sampled voltage and a preset mapping table.

[0081] The mapping table indicates the mapping relationship between open circuit voltage and depth of discharge. The open circuit voltage (OCV) represents the potential difference between the positive and negative electrodes of the battery, and the depth of discharge (DOD) represents the percentage of the battery's discharge capacity to the rated capacity of the battery.

[0082] The ampere-hour integration method estimates the battery's state of charge based on certain external system characteristics, such as current, time, temperature compensation, etc. The sampling voltage and mapping table are used to determine the initial depth of discharge.

[0083] The controller first retrieves a preset mapping table that indicates the mapping relationship between open-circuit voltage and depth of discharge. Then, referring to this mapping table, it determines the battery's initial depth of discharge (DOD0) when the controller is powered on, based on the sampled voltage. The sampled voltage is the sampled value of the open-circuit voltage. The initial depth of discharge (DOD0) represents the percentage of the battery's discharge capacity, as determined by the current sampled voltage, relative to the rated capacity, when the battery is first powered on.

[0084] The mapping table is shown in Table 1.

[0085]

[0086] Table 1

[0087] The OCV-DOD relationship curve can be generated offline according to the mapping table. The following steps can be used to obtain the mapping table:

[0088] Step 1: At 25°C, charge the battery with constant current and then constant voltage, with a constant voltage charging voltage of 4.2V, a constant current charging current of 1C, and a cut-off current of 0.02C. Charge the battery to full power and let it rest for 2 hours. Allow the battery to fully rest at 25°C to obtain the OCV at the DOD point.

[0089] Step 2: Discharge 2% of the nominal capacity at a 0.5C discharge rate, let it rest for 45 minutes, and obtain the OCV at that DOD point. The nominal capacity refers to the minimum amount of electricity that should be discharged under certain discharge conditions, as specified or guaranteed during the design and manufacture of the battery.

[0090] Step 3: Repeat step 2 10 times;

[0091] Step 4: Discharge 5% of the nominal capacity at a 0.5C discharge rate, let it rest for 45 minutes, and obtain the OCV at that DOD point.

[0092] Step 5: Repeat step 4 12 times;

[0093] Step 6: Discharge 2% of the nominal capacity at a 0.5C discharge rate, let it rest for 45 minutes, and obtain the OCV at that DOD point.

[0094] Step 7: Repeat step 6 until the battery is discharged to the discharge cut-off voltage;

[0095] Step 8: Based on the test results, the battery OCV-DOD mapping relationship can be obtained. Using the cubic spline interpolation method, this mapping relationship is organized into a mapping table 1 with a discharge depth of 10% as a step size.

[0096] Step 202: Determine a first capacity of current flowing through the battery after power-on based on the sampled current and a preset integration time step.

[0097] The controller calculates the capacity Qpass=∫I*Δt flowing through the battery pack after the controller is powered on based on the sampled current I, where Qpass is the first capacity, I is the sampled current, and Δt is the integration time step.

[0098] The first capacity is the capacity value obtained after the current sampling current flows through the battery at the integration time step. After discretization, the time dt becomes the time interval Δt, also called the integration time step.

[0099] Step 203: Determine a second capacity of the battery released from full charge to empty charge at a set rate at the sampling temperature.

[0100] The second capacity of the battery released from full charge to empty at a set rate at the sampling temperature T can be determined by looking up a table, such as Table 2 (T-Capacities Table), which shows the capacity that the battery can release from full charge to empty at a 1C discharge rate at different temperatures, where Capacities is the second capacity.

[0101] temperature(℃) -10 0 10 25 40 capacity(mAh) 2187 2254 2288 2328 2360

[0102] Table 2

[0103] Step 204: Calculate the integrated discharge depth according to the initial discharge depth, the first capacity, and the second capacity.

[0104] The calculation formula for the integrated discharge depth is:

[0105] DODah=DOD0-Qpass / QT, where DODah is the integrated depth of discharge, DOD0 is the initial depth of discharge, Qpass is the first capacity, and QT is the second capacity.

[0106] As an optional implementation, Figure 3 As shown, the battery sampling values include sampling voltage, sampling current and sampling temperature; the battery sampling values and the integrated discharge depth are input into the equivalent circuit model to obtain the battery open circuit voltage, which includes:

[0107] Step 301: Determine the target DC impedance of the battery according to the integrated discharge depth, the sampled temperature and a preset parameter table.

[0108] The parameter table is used to indicate the corresponding relationship between the integrated discharge depth, the sampling temperature and the target DC impedance, and the target DC impedance is used to indicate the ability of the component to block direct current.

[0109] The equivalent circuit model uses a circuit network composed of traditional circuit elements such as resistors, capacitors, and voltage sources to describe the external characteristics of a power battery. This model uses a voltage source to represent the thermodynamic equilibrium potential of the power battery and an RC network to describe the kinetic characteristics of the power battery. The equivalent circuit model can be either a Rint model or a Thevenin model. This application does not impose any specific restrictions on the model used in the equivalent circuit model.

[0110] The controller obtains a preset parameter table, and performs a lookup based on the obtained integrated discharge depth and the sampled temperature in combination with the parameter table to obtain a target direct current resistance (DCR) of the battery.

[0111] The optional parameters in this embodiment are shown in Table 3.

[0112]

[0113] Table 3

[0114] Table 3 is a pre-generated DOD-T-DCR table, i.e., the parameter table mentioned in the embodiment of this application. The method for generating Table 3 is as follows:

[0115] The method for generating the parameter table includes: charging multiple batteries with constant current and then constant voltage until they are fully charged; performing a first operation on multiple batteries that have been stationary for a preset time at different stationary temperatures at multiple different discharge rates to obtain multiple reference battery internal resistances of the multiple batteries at different stationary temperatures, the first operation includes: discharging the battery to the cut-off voltage according to the discharge rate, and obtaining the battery voltage and discharge depth corresponding to each change in the preset depth, and obtaining the reference battery internal resistance according to the preset mapping table, discharge depth, battery voltage and discharge rate; performing a second operation on the multiple reference battery internal resistances to obtain multiple target battery internal resistances at different stationary temperatures, the second operation includes: averaging the multiple reference battery internal resistances obtained by performing the first operation on multiple batteries at the same stationary temperature at different discharge rates to obtain the target battery internal resistance; generating a parameter table according to the multiple target battery internal resistances, the corresponding multiple discharge depths and the corresponding multiple stationary temperatures.

[0116] For example, Table 3 can be obtained through the following specific implementation process:

[0117] 1. At 25°C, charge the battery to full capacity using constant current and then constant voltage charging, with a constant voltage charging voltage of 4.2V, a constant current charging current of 1C, and a cut-off current of 0.02C.

[0118] 2. Adjust the incubator temperature so that the battery can be fully rested at -10°C;

[0119] 3. Discharge the battery to the cutoff voltage at different discharge rates (e.g., 0.5C, 1C, and 1.5C). Record the battery voltage CV(k) for each 5% increase in DOD. k is the recording sequence number, k = 1, 2, 3, ... 21. Record the battery voltage once for each 5% increase in DOD, for a total of 21 recordings. CV(k) is the battery voltage at DOD = 0%, 5%, ... 100%. The target depth of discharge is any value between 0%, 5%, ... 100%.

[0120] 4. Obtain OCV(k) at different DODs according to Table 1. OCV(k) is the calculated open circuit voltage of the battery when DOD = 0%, 5%...100%;

[0121] 5. Calculate the DC resistance DCR(k) = (CV(k) - OCV(k)) / cur. After averaging the battery internal resistance at different discharge rates at the same temperature, a curve with a DOD step size of 5% can be obtained. Based on this curve, the data at T = -10°C in the DOD-T-DCR table can be obtained.

[0122] 6. Adjust the incubator temperature so that the battery can stand still at -10°C. Repeat steps 3 to 5 to obtain the data when T is -25°C in the DOD-T-DCR table.

[0123] 7. Adjust the incubator temperature so that the battery can stand still at -10°C. Repeat steps 3 to 5 to obtain the data when T is -50°C in the DOD-T-DCR table.

[0124] In this application, the DCR test in Table 3 is to obtain the DC internal resistance of the battery at different temperatures under constant current state, rather than the HPPC internal resistance, etc.

[0125] Step 302: Calculate the battery open circuit voltage according to the sampled voltage, the sampled current and the target DC impedance.

[0126] The calculation formula for the battery open circuit voltage is:

[0127] OCVest=UI*DCR, where OCVest is the open circuit voltage of the battery, U is the sampling voltage, I is the sampling current, and DCR is the target DC resistance.

[0128] The controller first obtains the target DC resistance DCR based on the integrated discharge depth DODah and the sampled temperature T, combined with the offline calibrated (i.e., pre-generated) DOD-T-DCR table, and then obtains the battery open circuit voltage OCVest by combining the sampled voltage and sampled current.

[0129] As an optional implementation, Figure 4 As shown, the battery open circuit voltage is transformed into a curve to obtain the battery discharge depth:

[0130] Step 401: Determine the static open circuit voltage of the battery after it is discharged to the cut-off voltage under the current battery operating condition, and obtain a preset open circuit voltage according to a preset mapping table.

[0131] The current battery operating condition includes the preset battery undervoltage protection voltage, the current current, and the battery internal resistance when the battery is discharged. The controller calculates the static open-circuit voltage of the battery after it is discharged to the cut-off voltage based on the battery undervoltage protection voltage, the current current, and the battery internal resistance when the battery is discharged.

[0132] The battery undervoltage protection voltage refers to the voltage at which the power supply is cut off when the battery voltage drops below a certain level. The purpose of undervoltage protection is to prevent equipment from burning out due to overload. The static open-circuit voltage refers to the open-circuit voltage value obtained when the battery is discharged to the cutoff voltage under the current battery operating conditions.

[0133] The controller obtains a first open-circuit voltage corresponding to DOD = 0% and a second open-circuit voltage corresponding to DOD = 100% according to a preset mapping table 1, and then uses the first open-circuit voltage and the second open-circuit voltage as the preset open-circuit voltage. In other words, the preset open-circuit voltage includes the open-circuit voltage values corresponding to DOD = 0% and DOD = 100%, respectively.

[0134] Specifically, in the embodiment of the present application, the specific calculation formula of the static open circuit voltage is as follows:

[0135] OCVempty=Uuvp-I*DCRempty, where OCVempty is the static open-circuit voltage, Uuvp is the preset battery undervoltage protection voltage, I is the current current, and DCRempty is the battery internal resistance when the battery is discharged. That is, DCRempty is the internal resistance value corresponding to the temperature T and DOD=100% in Table 3.

[0136] Step 402: Performing proportional curve transformation on the battery open circuit voltage according to the static open circuit voltage and the preset open circuit voltage to obtain an intermediate open circuit voltage.

[0137] The controller obtains a static open-circuit voltage and a preset open-circuit voltage, wherein the preset open-circuit voltage includes a first open-circuit voltage when the battery is fully charged and a second open-circuit voltage obtained after the battery is discharged at a preset rate to a cutoff voltage and left to stand. The controller then performs an isoproportional curve transformation on the battery open-circuit voltage based on the static open-circuit voltage, the first open-circuit voltage, and the second open-circuit voltage to obtain an intermediate open-circuit voltage.

[0138] The calculation formula for the intermediate open circuit voltage is:

[0139] OCVconv=OCVfull-(OCVfull-OCVcenter)(OCVfull-OCVest) / (OCVfull-OCVempty)

[0140] Among them, OCVconv is the intermediate open-circuit voltage; OCVfull is the first open-circuit voltage when the battery is fully charged, that is, the open-circuit voltage value corresponding to DOD = 0% in Table 1; OCVcenter is the second open-circuit voltage obtained by the battery being discharged to the cut-off voltage at a preset discharge rate and then allowed to stand, that is, the open-circuit voltage value corresponding to DOD = 100% in Table 1. For example, the preset discharge rate is 0.5C; OCVempty is the static open-circuit voltage.

[0141] The intermediate open circuit voltage refers to the voltage value obtained by performing an equal-proportional curve transformation on the battery open circuit voltage based on the static open circuit voltage and the preset open circuit voltage.

[0142] Step 403: Calculate the battery discharge depth according to the intermediate open circuit voltage and the preset polynomial fitting coefficient.

[0143] Specifically, in the embodiment of the present application, the calculation process of the battery discharge depth can be obtained in the following way:

[0144] Determine the open circuit voltage OCV(k) corresponding to each depth of discharge DOD according to the mapping table Table 1;

[0145] Calculating and determining a variance voltage OCVscale according to the multiple open circuit voltages OCV(k), where the variance voltage is the variance value of the multiple open circuit voltages OCV(k);

[0146] Determine an intermediate value (OCVconv-OCVcenter) / OCVscale according to the intermediate open circuit voltage OCVconv, the second open circuit voltage OCVcenter and the variance voltage OCVscale;

[0147] The battery discharge depth is calculated based on the intermediate values and polynomial fitting coefficients. The specific calculation formula is as follows:

[0148] DODest=p1+p2*(OCVconv-OCVcenter) / OCVscale+p3*((OCVconv-OCVcenter) / OCVscale)^2+...+p6*((OCVconv-OCVcenter) / OCVscale)^5.

[0149] Wherein, DODest is the battery discharge depth, and the polynomial fitting coefficient is a fifth-order polynomial fitting coefficient, specifically p1 to p6 as shown in Table 4.

[0150] p1 p2 p3 p4 p5 p6 -219 2054 -6555 7358 -3419 10104

[0151] Table 4

[0152] The polynomial fitting coefficients are obtained by the following method:

[0153] Performing centering and scaling transformation on the open circuit voltage OCV(k) according to the second open circuit voltage OCVcenter and the variance voltage OCVscale to obtain a transformed voltage OCVcs(k);

[0154] The calculation formula for performing centralization and scaling transformation on the open-circuit voltage to obtain the transformed voltage is as follows:

[0155] OCVcs(k)=(OCV(k)-OCVcenter) / OCVscale;

[0156] The polynomial fitting coefficients are calculated based on the conversion voltage OCVcs(k) and the battery depth of discharge DOD.

[0157] As an optional implementation, based on the current battery operating condition of the battery, the calculation formula for the battery state of charge is:

[0158] When I>0, SOC(k-1)>(1-DODest), then SOC(k)=SOC(k-1), otherwise SOC(k)=1-DODest;

[0159] When I<=0, SOC(k-1)>(1-DODest), then SOC(k)=1-DODest, otherwise SOC(k)=SOC(k-1).

[0160] Among them, the current I>0 is the charging state, and I<0 is the discharging state.

[0161] k is the record number;

[0162] When k = 1, DOD = 0% SOC (1);

[0163] When k = 2, DOD = 5% SOC (2);

[0164] …

[0165] When k=21, DOD=100%SOC(21).

[0166] Based on the same technical concept, the embodiment of the present application also provides a SOC estimation device with self-adjusting zero point, such as Figure 5 As shown, the device includes:

[0167] An acquisition module 501 is used to obtain a battery sampling value under a current battery operating condition;

[0168] The processing module 502 is used to process the battery sample value by using the ampere-hour integration method and the equivalent circuit model to obtain the battery open circuit voltage;

[0169] The conversion module 503 is used to perform curve conversion on the battery open circuit voltage to obtain the battery discharge depth;

[0170] The correction module 504 is used to correct the battery discharge depth according to the current battery operating condition of the battery to obtain the battery state of charge.

[0171] Optionally, the processing module 502 includes:

[0172] The first input unit is used to calculate and process the battery sampling value by the ampere-hour integration method to obtain the integrated discharge depth;

[0173] The second input unit is used to input the battery sampling value and the integrated discharge depth into the equivalent circuit model to obtain the battery open circuit voltage.

[0174] Optionally, the battery sampling value includes a sampled voltage, a sampled current, and a sampled temperature, and the first input unit is used to:

[0175] Determine the initial discharge depth of the battery at power-on based on the sampled voltage and a preset mapping table;

[0176] Determine a first capacity of the battery flowing through after power-on based on the sampled current and a preset integration time step;

[0177] Determine the second capacity of the battery released from full charge to empty at a set rate at the sampling temperature;

[0178] An integrated depth of discharge is calculated based on the initial depth of discharge, the first capacity, and the second capacity.

[0179] Optionally, the battery sampling value includes a sampling voltage, a sampling current, and a sampling temperature; and the second input unit is used to:

[0180] Determine the target DC impedance of the battery based on the integrated discharge depth, sampling temperature and a preset parameter table;

[0181] Calculate the battery open circuit voltage based on the sampled voltage, sampled current and target DC impedance.

[0182] Optionally, the device is also used to:

[0183] Charge multiple batteries with constant current and then constant voltage until they are fully charged;

[0184] performing a first operation at a plurality of different discharge rates on a plurality of batteries that have been stationed for a preset time period at different stationary temperatures to obtain a plurality of reference battery internal resistances of the plurality of batteries at the different stationary temperatures, the first operation comprising: discharging the battery to a cutoff voltage at the discharge rate, obtaining the battery voltage and discharge depth corresponding to each change in the preset depth, and obtaining the reference battery internal resistance based on a preset mapping table, the discharge depth, the battery voltage, and the discharge rate;

[0185] Performing a second operation on the multiple reference battery internal resistances to obtain multiple target battery internal resistances at different resting temperatures, the second operation comprising: averaging the multiple reference battery internal resistances obtained by performing the first operation on the multiple batteries at the same resting temperature at different discharge rates to obtain the target battery internal resistance;

[0186] A parameter table is generated according to a plurality of target battery internal resistances, a corresponding plurality of discharge depths, and a corresponding plurality of rest temperatures.

[0187] Optionally, the transformation module 503 includes:

[0188] a determination unit, configured to obtain a static open circuit voltage of the battery when the battery is discharged to a cut-off voltage under a current battery operating condition, and obtain a preset open circuit voltage according to a preset mapping table;

[0189] a conversion unit, configured to perform proportional curve conversion on the battery open circuit voltage according to the static open circuit voltage and the preset open circuit voltage to obtain an intermediate open circuit voltage;

[0190] The calculation unit is used to calculate the battery discharge depth according to the intermediate open circuit voltage and the preset polynomial fitting coefficient result.

[0191] Optionally, the determination unit is used to:

[0192] Get the preset battery undervoltage protection voltage, current current, and battery internal resistance when the battery is discharged;

[0193] Calculate the static open-circuit voltage of the battery after it is discharged to the cutoff voltage under the current battery operating conditions based on the battery undervoltage protection voltage, current current, and the battery internal resistance when the battery is discharged.

[0194] Optionally, the preset open circuit voltage includes a first open circuit voltage when the battery is fully charged and a second open circuit voltage obtained when the battery is discharged at a preset rate to a cutoff voltage and then left to stand.

[0195] Optionally, the computing unit is used to:

[0196] Obtaining multiple open circuit voltages corresponding to multiple discharge depths according to a mapping table, and using the multiple open circuit voltages to calculate a variance voltage;

[0197] Obtaining an intermediate value according to the intermediate open circuit voltage, the second open circuit voltage and the variance voltage;

[0198] The battery discharge depth is calculated based on the intermediate values and the polynomial fitting coefficients.

[0199] Optionally, the computing unit is further configured to:

[0200] performing centralization and scaling transformation on the open circuit voltage according to the second open circuit voltage and the variance voltage to obtain a transformed voltage;

[0201] According to the transformation voltage and discharge depth, the multi-order polynomial fitting coefficient results are calculated.

[0202] According to another aspect of the embodiment of the present application, the present application provides an electronic device, such as Figure 6 As shown, it includes a memory 603, a controller 601, a communication interface 602 and a communication bus 604. The memory 603 stores a computer program that can be run on the controller 601. The memory 603 and the controller 601 communicate through the communication interface 602 and the communication bus 604. When the controller 601 executes the computer program, the steps of the above method are implemented.

[0203] The memory and controller in the electronic device communicate via a communication bus and a communication interface. The communication bus can be a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus. The communication bus can be divided into an address bus, a data bus, a control bus, and the like.

[0204] The memory may include a random access memory (RAM) or a non-volatile memory, such as at least one disk storage. Alternatively, the memory may be at least one storage device located away from the controller.

[0205] The above-mentioned controller can be a general controller, including a central processing unit (CPU), a network processor (NP), etc.; it can also be a digital signal processing controller (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components.

[0206] According to another aspect of the embodiments of the present application, a computer-readable medium having non-volatile program code executable by a controller is provided.

[0207] Optionally, in an embodiment of the present application, a computer-readable medium is configured to store program code for the controller to execute the above method.

[0208] Optionally, the specific examples in this embodiment may refer to the examples described in the above embodiments, and this embodiment will not be described in detail here.

[0209] When implementing the embodiments of the present application, reference may be made to the above embodiments, which have corresponding technical effects.

[0210] It is understood that the embodiments described herein may be implemented using hardware, software, firmware, middleware, microcode, or a combination thereof. For hardware implementation, the processing unit may be implemented in one or more application-specific integrated circuits (ASICs), digital signal controllers (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field-programmable gate arrays (FPGAs), general-purpose controllers, controllers, microcontrollers, microcontrollers, other electronic units for performing the functions described herein, or a combination thereof.

[0211] For software implementation, the technology described herein can be implemented by a unit that performs the functions described herein. The software code can be stored in a memory and executed by a controller. The memory can be implemented in the controller or external to the controller.

[0212] Those skilled in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0213] Those skilled in the art will clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0214] In the embodiments provided in this application, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are merely schematic. For example, the division of the modules is merely a logical function division. In actual implementation, there may be other division methods, such as multiple modules or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interfaces, devices or units, which can be electrical, mechanical or other forms.

[0215] The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of these units may be selected to achieve the purpose of this embodiment according to actual needs.

[0216] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0217] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solutions of the embodiments of the present application are essentially or partly contributed to the prior art or part of the technical solutions can be embodied in the form of a software product, which is stored in a storage medium and includes several instructions for causing a computer device (which can be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in each embodiment of the present application. The aforementioned storage medium includes various media that can store program codes, such as a USB flash drive, a mobile hard drive, a ROM, a RAM, a magnetic disk, or an optical disk. It should be noted that, in this article, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such a process, method, article or device. Without further constraints, an element defined by the phrase "comprises a..." does not preclude the existence of additional identical elements in the process, method, article or apparatus that includes the element.

[0218] The foregoing is merely a list of specific embodiments of the present application, intended to enable those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application is not limited to the embodiments shown herein, but is intended to conform to the broadest scope consistent with the principles and novel features of the present application.

Claims

1. A method for estimating SOC with self-adjusting zero point, characterized in that: The method comprises: Get the battery sampling value under the current battery working condition; Processing the battery sample value by using the ampere-hour integration method and the equivalent circuit model to obtain the battery open circuit voltage; Performing curve transformation on the open circuit voltage of the battery to obtain the battery discharge depth; Correcting the battery discharge depth according to the current battery operating condition to obtain the battery state of charge; The battery state of charge can be smoothly adjusted to zero along with the converted battery open circuit voltage without jumping; The performing curve transformation on the battery open circuit voltage to obtain the battery discharge depth includes: obtaining the static open circuit voltage of the battery when discharged to the cutoff voltage under the current battery operating condition, and obtaining a preset open circuit voltage according to a preset mapping table, wherein the mapping table is used to indicate a mapping relationship between the open circuit voltage and the discharge depth; performing an iso-proportional curve transformation on the battery open circuit voltage according to the static open circuit voltage and the preset open circuit voltage to obtain an intermediate open circuit voltage; and calculating the battery discharge depth according to the intermediate open circuit voltage and a preset polynomial fitting coefficient result. Wherein, obtaining the preset open circuit voltage according to the preset mapping table includes: obtaining, according to the preset mapping table, a first open circuit voltage corresponding to a discharge depth of 0% and a second open circuit voltage corresponding to a discharge depth of 100%, and using the first open circuit voltage and the second open circuit voltage as the preset open circuit voltage; The preset open circuit voltage includes a second open circuit voltage obtained by discharging the battery at a preset rate to a cutoff voltage and then allowing the battery to stand; calculating the battery discharge depth based on the intermediate open circuit voltage and the polynomial fitting coefficient result includes: obtaining multiple open circuit voltages corresponding to multiple discharge depths according to the mapping table, and using the multiple open circuit voltages to calculate a variance voltage; obtaining an intermediate value based on the intermediate open circuit voltage, the second open circuit voltage, and the variance voltage; and calculating the battery discharge depth based on the intermediate value and the polynomial fitting coefficient.

2. The method according to claim 1, characterized in that Processing the battery sample value by using the ampere-hour integration method and the equivalent circuit model to obtain the battery open circuit voltage includes: Calculating and processing the battery sampling value by the ampere-hour integration method to obtain the integrated discharge depth; The battery sampling value and the integrated discharge depth are input into an equivalent circuit model to obtain the battery open circuit voltage.

3. The method according to claim 2, characterized in that The battery sampling values include sampling voltage, sampling current and sampling temperature; The calculating and processing the battery sampling value by the ampere-hour integration method to obtain the integrated discharge depth includes: Determining an initial depth of discharge of the battery upon power-on based on the sampled voltage and a preset mapping table; Determining a first capacity of current flowing through the battery after power-on based on the sampled current and a preset integration time step; Determine a second capacity of the battery released from full charge to empty charge at a set rate at the sampling temperature; An integrated depth of discharge is calculated based on the initial depth of discharge, the first capacity, and the second capacity.

4. The method according to claim 2, characterized in that The battery sampling values include sampling voltage, sampling current and sampling temperature; Inputting the battery sampling value and the integrated discharge depth into an equivalent circuit model to obtain the battery open circuit voltage includes: Determining a target DC impedance of the battery according to the integrated discharge depth, the sampling temperature, and a preset parameter table; The battery open circuit voltage is calculated according to the sampled voltage, the sampled current and the target DC impedance.

5. The method according to claim 4, characterized in that The method further includes: obtaining a preset parameter table; correspondingly, obtaining the preset parameter table includes: Charge multiple batteries with constant current and then constant voltage until they are fully charged; performing a first operation on a plurality of batteries that have been stationed for preset periods of time at different stationary temperatures at a plurality of different discharge rates to obtain a plurality of reference battery internal resistances of the plurality of batteries at the different stationary temperatures, the first operation comprising: discharging the battery to a cutoff voltage at the discharge rate, obtaining the battery voltage and discharge depth corresponding to each change in the preset depth, and obtaining the reference battery internal resistance based on a preset mapping table, the discharge depth, the battery voltage, and the discharge rate; performing a second operation on the multiple reference battery internal resistances to obtain multiple target battery internal resistances at different resting temperatures, the second operation comprising: averaging the multiple reference battery internal resistances obtained by performing the first operation on the multiple batteries at the same resting temperature at different discharge rates to obtain the target battery internal resistance; The parameter table is generated according to a plurality of target battery internal resistances, a plurality of corresponding discharge depths, and a plurality of corresponding rest temperatures.

6. The method according to claim 1, characterized in that The obtaining of the static open circuit voltage of the battery when the battery is discharged to the cut-off voltage under the current battery operating condition includes: Get the preset battery undervoltage protection voltage, current current, and battery internal resistance when the battery is discharged; Calculate the static open-circuit voltage of the battery after it is discharged to the cutoff voltage under the current battery operating condition according to the battery undervoltage protection voltage, the current current, and the battery internal resistance when the battery is discharged.

7. The method according to claim 6, characterized in that The polynomial fitting coefficients are obtained by the following method: performing a centering process and a scaling transformation on the open circuit voltage according to the second open circuit voltage and the variance voltage to obtain a transformed voltage; A polynomial fitting coefficient result is calculated based on the conversion voltage and the battery discharge depth.

8. A SOC estimation device with self-adjusting zero point, characterized in that: The device comprises: The acquisition module is used to obtain the battery sampling value under the current battery working condition; a processing module, configured to process the battery sampling value by using an ampere-hour integration method and an equivalent circuit model to obtain a battery open circuit voltage; A conversion module, used to perform curve conversion on the battery open circuit voltage to obtain the battery discharge depth; a correction module, configured to correct the battery depth of discharge according to a current battery operating condition of the battery to obtain a battery state of charge, wherein the battery state of charge can be smoothly adjusted to zero along with the converted battery open circuit voltage without abrupt changes; The conversion module is configured to: obtain the static open circuit voltage of the battery when it is discharged to the cutoff voltage under the current battery operating condition, and obtain a preset open circuit voltage according to a preset mapping table, wherein the mapping table is used to indicate a mapping relationship between the open circuit voltage and the depth of discharge; perform an isoproportional curve transformation on the battery open circuit voltage according to the static open circuit voltage and the preset open circuit voltage to obtain an intermediate open circuit voltage; and calculate the battery depth of discharge according to the intermediate open circuit voltage and a preset polynomial fitting coefficient result; The conversion module is specifically configured to: obtain, according to a preset mapping table, a first open circuit voltage corresponding to a discharge depth of 0% and a second open circuit voltage corresponding to a discharge depth of 100%, and use the first open circuit voltage and the second open circuit voltage as the preset open circuit voltage; The preset open-circuit voltage includes a second open-circuit voltage obtained after the battery is discharged at a preset rate to a cut-off voltage and left to stand; the conversion module is specifically used to: obtain multiple open-circuit voltages corresponding to multiple depths of discharge according to the mapping table, and the multiple open-circuit voltages are used to calculate a variance voltage; obtain an intermediate value based on the intermediate open-circuit voltage, the second open-circuit voltage, and the variance voltage; and calculate the battery discharge depth based on the intermediate value and the polynomial fitting coefficient.

9. An electronic device, characterized in that: It includes a controller, a communication interface, a memory and a communication bus, wherein the controller, the communication interface and the memory communicate with each other via the communication bus; Memory for storing computer programs; The controller is configured to implement the SOC estimation method with self-adjusting zero point according to any one of claims 1 to 7 when executing a program stored in the memory.

10. A computer-readable storage medium, characterized in that The computer-readable storage medium stores a computer program, and when the computer program is executed by the controller, the SOC estimation method with self-adjusting zero point according to any one of claims 1 to 7 is implemented.

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