Open circuit voltage model generation and charge state estimation method and device

Abstract

The present application provides a method and device for generating an open circuit voltage model and estimating the state of charge. In the field of battery technology, the method for generating an open circuit voltage model includes: obtaining a dynamic voltage equivalent circuit of a battery device; obtaining an initial model of the open circuit voltage according to the dynamic voltage equivalent circuit; collecting battery status data of the battery device, the battery status data including an open circuit voltage and a dynamic voltage; based on the initial model, fitting the battery status data to obtain the values ​​of the constant coefficients in the initial model; determining the open circuit voltage model according to the values ​​of the constant coefficients and the initial model, the open circuit voltage model is used to characterize the relationship between the dynamic voltage and the open circuit voltage. The embodiments of the present application can improve the calculation accuracy of the open circuit voltage, thereby improving the SOC estimation accuracy.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a method and device for generating an open circuit voltage model and estimating a state of charge. Background Art

[0002] Real-time and accurate estimation of the SOC (State of Charge) of the battery device plays an important role in realizing the battery management system's power indication, remaining mileage, overcharge and over-discharge protection, battery balancing, charging control, and battery health status prediction.

[0003] At present, the commonly used SOC estimation methods include offline testing, that is, pre-establishing a three-dimensional data table consisting of temperature, SOC, and OCV (open circuit voltage) of the battery pack in a static state through offline testing; calculating the real-time OCV of the battery pack by detecting whether the electric vehicle is in a temporary parking state, and querying the SOC based on the OCV value. However, the limitations of the current offline testing method are: offline calibration relies on a purely mechanistic electrochemical model, which is complex to derive and difficult to calculate, and is very time-consuming and resource-intensive. In addition, the operating condition data of offline calibration often cannot meet the actual driving conditions, lacks interpretability, and the calculation accuracy of the open circuit voltage is not high, resulting in difficulty in guaranteeing the accuracy of the estimated SOC.

[0004] It should be noted that the above statements are only used to provide background technical information related to the present application and do not necessarily constitute prior art. Summary of the invention

[0005] In view of this, the purpose of the present application is to propose a method and device for generating an open circuit voltage model and estimating the state of charge. The present application can specifically solve the problem that the existing calculation accuracy of the open circuit voltage is not high, resulting in low SOC estimation accuracy.

[0006] Based on the above-mentioned purpose, in a first aspect, the present application proposes a method for generating an open circuit voltage model, the method comprising: obtaining a dynamic voltage equivalent circuit of a battery device; obtaining an initial model of the open circuit voltage based on the dynamic voltage equivalent circuit, the initial model comprising constant coefficients with unknown values; collecting battery status data of the battery device, the battery status data comprising an open circuit voltage and a dynamic voltage, the battery status data being obtained by screening discharge condition data in historical charge and discharge data; fitting the battery status data based on the initial model to obtain the values ​​of each constant coefficient in the initial model; determining the open circuit voltage model based on the values ​​of each constant coefficient and the initial model, the open circuit voltage model being used to characterize the relationship between the dynamic voltage and the open circuit voltage.

[0007] The open circuit voltage model of this embodiment is obtained based on the dynamic voltage equivalent circuit model of the battery, has reliable theoretical support and high accuracy. The parameters of the open circuit voltage model are obtained based on the battery status data, so that the parameters of the open circuit voltage model have high accuracy, are more in line with the actual working conditions, and can greatly improve the SOC estimation accuracy.

[0008] In some embodiments, the dynamic voltage equivalent circuit includes an open circuit voltage source, a circuit impedance, and a polarization resistor connected in series; according to the dynamic voltage equivalent circuit, an initial model of the open circuit voltage is obtained, including: according to the dynamic voltage equivalent circuit, respectively obtaining the voltage division of the open circuit voltage source, the voltage division of the circuit impedance, and the voltage division of the polarization resistor, the open circuit voltage is the voltage division of the open circuit voltage source; according to the voltage division of the open circuit voltage source, the voltage division of the circuit impedance, and the voltage division of the polarization resistor, the initial model of the open circuit voltage is generated.

[0009] In the above manner, the open circuit voltage model is obtained based on the dynamic voltage equivalent circuit model of the battery, which has reliable theoretical support and high accuracy.

[0010] In some embodiments, the initial model of the open circuit voltage is generated based on the voltage division of the open circuit voltage source, the voltage division of the circuit impedance, and the voltage division of the polarization resistor, and also includes: generating the initial model of the open circuit voltage based on the voltage division of the open circuit voltage source, the voltage division of the circuit impedance, the voltage division of the polarization resistor, and preset influencing parameters of the voltage division of the polarization resistor; the preset influencing parameters include one or more of the battery state of charge, temperature, current, and discharge depth of the battery device.

[0011] In this embodiment, the influence of the battery temperature, the impedance voltage, the discharge depth and the polarization voltage of the battery on the open circuit voltage can be taken into account in the above manner, thereby improving the accuracy of the open circuit voltage model.

[0012] In some embodiments, collecting the battery status data of the battery device includes: extracting discharge condition data from historical charge and discharge data of the battery device; filtering out spare data in which the standing time at the end of discharge is greater than a preset time from the discharge condition data; and obtaining the battery status data based on the spare data.

[0013] In this way, spare data with a static time at the end of discharge greater than a preset time is selected from the discharge condition data. The open circuit voltage in the spare data tends to be stable, and the battery status data obtained based on the spare data is more consistent with the actual working conditions, which can improve the reliability of the model.

[0014] In some embodiments, the battery status data is obtained based on the backup data, including: for each operating condition in the backup data, the battery static voltage at the discharge end corresponding to each operating condition is used as the open circuit voltage, and the dynamic voltage at the discharge end corresponding to each operating condition is used as the dynamic voltage, as a set of status data, to obtain multiple sets of status data; and the battery status data is obtained based on the multiple sets of status data.

[0015] The static voltage and dynamic voltage in the battery status data obtained in the above manner are obtained based on historical actual operating condition data. Using this battery status data to fit the open circuit voltage model can improve the model accuracy.

[0016] In some embodiments, obtaining the battery status data according to the multiple groups of status data includes: filtering the multiple groups of status data according to whether the current at the end of discharge is within a preset current range to obtain the battery status data.

[0017] This can reduce the impact of ohmic polarization caused by current on the accuracy of the open circuit voltage model.

[0018] In some embodiments, based on the initial model, the battery status data is fitted to obtain the values ​​of the constant coefficients in the initial model, including: based on the initial model, the battery status data is fitted to obtain multiple fitted open circuit voltage curves; based on the open circuit voltage and the dynamic voltage, the real open circuit voltage curve of the battery device is obtained; among the multiple fitted open circuit voltage curves, a fitted open circuit voltage curve with the smallest error with the real open circuit voltage curve is obtained as a target curve; and the values ​​of the constant coefficients in the target curve are obtained as the values ​​of the constant coefficients in the initial model.

[0019] In this way, by fitting the battery status data, the model can more accurately reflect the actual behavior of the battery, more accurately describe the dynamic and static characteristics of the battery, improve the accuracy of the model prediction, and obtain a more accurate open circuit voltage, so as to more accurately estimate the SOC of the battery device.

[0020] In a second aspect, a method for estimating a state of charge is also provided, the method comprising: collecting battery status data of a battery device, the battery status data comprising a real-time dynamic voltage; based on the battery status data, obtaining the open circuit voltage of the battery device using an open circuit voltage model; the open circuit voltage model is a model obtained using the open circuit voltage model generation method described in any one of the first aspects; obtaining the battery state of charge of the battery device using the open circuit voltage and the corresponding relationship between the preset open circuit voltage and the battery state of charge.

[0021] In a third aspect, a device for generating an open circuit voltage model is also provided, wherein the device comprises:

[0022] A first acquisition module, used to acquire a dynamic voltage equivalent circuit of a battery device;

[0023] A model creation module, used to obtain an initial model of the open circuit voltage according to the dynamic voltage equivalent circuit, wherein the initial model contains constant coefficients of unknown values;

[0024] A second acquisition module, used for collecting battery status data of the battery device, wherein the battery status data includes an open circuit voltage and a dynamic voltage;

[0025] A data processing module, used for performing fitting processing on the battery state data based on the initial model to obtain the values ​​of the constant coefficients in the initial model;

[0026] The model determination module is used to determine the open circuit voltage model according to the values ​​of the constant coefficients and the initial model, and the open circuit voltage model is used to characterize the relationship between the dynamic voltage and the open circuit voltage.

[0027] In a fourth aspect, a state of charge estimation device is also provided, the device comprising: a collection unit, used to collect battery status data of a battery device, the battery status data comprising: an open circuit voltage and a real-time dynamic voltage; an open circuit voltage calculation unit, used to obtain the open circuit voltage of the battery device based on the battery status data using an open circuit voltage model; the open circuit voltage model is a model obtained using the open circuit voltage model generation method described in any one of the first aspects; an estimation unit, used to obtain the battery state of charge of the battery device using the open circuit voltage and a preset correspondence between the open circuit voltage and the battery state of charge.

[0028] In a fifth aspect, an electronic device is also provided, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the method described in any one of the first aspect and the second aspect.

[0029] In a sixth aspect, a computer-readable storage medium is also provided, on which a computer program is stored, and the program is executed by a processor to implement the method described in any one of the first and second aspects.

[0030] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In the accompanying drawings, unless otherwise specified, the same reference numerals throughout the multiple drawings represent the same or similar parts or elements. These drawings are not necessarily drawn to scale. It should be understood that these drawings only depict some embodiments disclosed in the present application and should not be regarded as limiting the scope of the present application. In addition, the same reference numerals are used to represent the same parts in all the drawings.

[0032] Figure 1 A flowchart showing the steps of the open circuit voltage model generation method of the present application;

[0033] Figure 2 A dynamic voltage equivalent circuit provided by an embodiment of the present application is shown;

[0034] Figure 3 The static state according to the embodiment of the present application is shown. Schematic diagram showing an approximately linear law with dynamic voltage;

[0035] Figure 4 A target curve effect diagram of this embodiment is shown;

[0036] Figure 5 The error distribution diagram of the dynamic SOC obtained in this embodiment is shown;

[0037] Figure 6 A flowchart showing a method for estimating a state of charge provided by an embodiment of the present application is shown;

[0038] Figure 7 A schematic structural diagram of an open circuit voltage model generating device of the present application is shown;

[0039] Figure 8 A schematic diagram of the structure of the charge state estimation device of the present application is shown;

[0040] Fig. 9 A schematic diagram of the structure of an electronic device provided by an embodiment of the present application is shown;

[0041] Fig.10 A schematic diagram of a storage medium provided in an embodiment of the present application is shown. DETAILED DESCRIPTION

[0042] The following embodiments of the technical solution of the present application are described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application, and are therefore only used as examples, and cannot be used to limit the scope of protection of the present application.

[0043] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0044] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0045] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0046] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, indicating that there may be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0047] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0048] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0049] Real-time and accurate estimation of the SOC (State of Charge) of the battery device plays an important role in realizing the battery management system's power indication, remaining mileage, overcharge and over-discharge protection, battery balancing, charging control, and battery health prediction. However, most of the current SOC estimation methods use offline calibration, which is difficult to calculate, time-consuming, and costly. It cannot meet the actual driving conditions, lacks interpretability, and has low accuracy in calculating the open circuit voltage, which makes it difficult to ensure the accuracy of the estimated SOC.

[0050] In order to solve the above problems, the embodiment of the present application provides an open circuit voltage model generation and state of charge estimation method, through the open circuit voltage model generation method to obtain an open circuit voltage model that can characterize the relationship between dynamic voltage and open circuit voltage, and then use the open circuit voltage model to estimate the state of charge, wherein the open circuit voltage model is obtained based on the equivalent circuit model, so that the open circuit voltage model has reliable mechanism support and strong theoretical explanation. The open circuit voltage model is driven by battery status data, which can improve the accuracy of the model, realize real-time prediction of open circuit voltage, simple calculation, no complex decoupling and more calculations are required, and can greatly improve the accuracy of SOC estimation.

[0051] The battery apparatus mentioned in the embodiments of the present application may include one or more battery cell assemblies for providing voltage and capacity. The battery cell assembly may include one or more battery cells, and the multiple battery cells are connected in series, in parallel or in mixed connection through a busbar.

[0052] In some embodiments, a battery cell assembly is generally formed by arranging a plurality of battery cells; as an example, a battery cell assembly may be a battery module, and a battery module is formed by arranging and fixing a plurality of battery cells to form an independent module. As an example, a battery module may be formed by bundling a plurality of battery cells by a cable tie.

[0053] In some embodiments, the battery device may be a battery pack, which includes a case and one or more battery cell assemblies, wherein the battery cell assemblies are accommodated in the case.

[0054] As an example, the battery cell assembly may be a battery module, and the battery cell assembly may be accommodated in the box by fixing the battery module in the box.

[0055] As an example, the battery cell assembly may also be housed in the case by directly fixing a plurality of battery cells to the case.

[0056] As an example, the box may include a first box and a second box. The first box and the second box are buckled together to form a closed space inside the box to accommodate the battery cell assembly. The closed here means covered or closed, which can be sealed or unsealed. The first box can be a top cover or a bottom plate.

[0057] As an example, the box body may include a top cover, a frame and a bottom plate. The top cover and the bottom plate are respectively connected to the frame, so that a closed space is formed inside the box body to accommodate the battery cell assembly.

[0058] As an example, the box body can be used as a part of the chassis structure of the vehicle. For example, the top cover of the box body can become at least a part of the floor of the vehicle, or the frame of the box body can become at least a part of the cross beam and longitudinal beam of the vehicle.

[0059] In some embodiments, the battery device refers to an energy storage device, which includes a box body, at least one side of which is provided with a door. The energy storage device includes an energy storage container, an energy storage cabinet, and the like.

[0060] The technical solutions described in the embodiments of the present application are applicable to various electrical devices using battery cells and battery devices, such as mobile phones, portable devices, laptop computers, electric vehicles, electric toys, electric tools, vehicles, ships and spacecraft, for example, spacecraft include airplanes, rockets, space shuttles and spacecraft, etc.

[0061] For the convenience of explanation, the following embodiments take the battery device of one embodiment of the present application as a battery pack as an example. In one example, the battery pack provides power for a vehicle, and the data of the battery pack can be obtained through the battery management system (BMS) of the vehicle.

[0062] Figure 1 The flow chart of the steps of the open circuit voltage model generation method of the present application is shown as follows: Figure 1 As shown, a method for generating an open circuit voltage model includes:

[0063] S101. Obtain a dynamic voltage equivalent circuit of a battery device.

[0064] S102. Obtain an initial model of the open circuit voltage according to the dynamic voltage equivalent circuit, wherein the initial model includes constant coefficients of unknown values.

[0065] S103 . Collect battery status data of the battery device, where the battery status data includes an open circuit voltage and a dynamic voltage.

[0066] S104: Based on the initial model, the battery status data is fitted to obtain the values ​​of the constant coefficients in the initial model.

[0067] S105 . Determine an open circuit voltage model according to the values ​​of the constant coefficients and the initial model. The open circuit voltage model is used to characterize the relationship between the dynamic voltage and the open circuit voltage.

[0068] In one example, the dynamic voltage equivalent circuit of the battery device is used to simulate the dynamic behavior of the battery during the charging and discharging process, for example, the Thevenin equivalent model circuit, the Rint model circuit, the DS-ECM dynamic integrated equivalent circuit model, etc.

[0069] In one example, the battery status data is obtained by screening the discharge condition data in the historical charge and discharge data. The battery status data can be collected by the vehicle's BMS system. Specifically, the battery status data can include the dynamic voltage and open circuit voltage of the battery under different charge and discharge states. It should be noted that in the actual implementation of this solution, some working data related to the properties of the battery cell itself can also be collected at the same time. For example, the current value, operating temperature, charge and discharge rate, charge and discharge depth, internal resistance, time series data, etc. of the battery device. The time series data can include recording the changes in battery status over time, including voltage changes in different stages such as static, charge and discharge, which helps to capture the dynamic changes in battery performance.

[0070] In this embodiment, the dynamic voltage equivalent circuit can characterize the relationship between the open circuit voltage and the dynamic voltage. Therefore, the initial model can also characterize the relationship between the open circuit voltage and the dynamic voltage. The initial model contains constant coefficients with unknown values. The constant coefficients need to be simulated and verified through actual data. Therefore, based on the initial model, the battery status data is fitted to obtain the values ​​of the constant coefficients in the initial model. In this way, the open circuit voltage model determined by the constant coefficients can be obtained.

[0071] As can be seen from the above embodiments, the open circuit voltage model of this embodiment is obtained based on the dynamic voltage equivalent circuit model of the battery, has reliable theoretical support, and is highly accurate. The parameters of the open circuit voltage model are obtained based on the battery status data, so that the parameters of the open circuit voltage model have high accuracy, are more in line with actual working conditions, and can greatly improve the SOC estimation accuracy.

[0072] In the embodiments of the present application, Figure 2 A dynamic voltage equivalent circuit provided by an embodiment of the present application is shown. Figure 2 As shown, the dynamic voltage equivalent circuit includes an open circuit voltage source U, a circuit impedance Ro, and a polarization resistor Rep connected in series. The divided voltage of the open circuit voltage source U is the open circuit voltage OCV, and the divided voltage of the circuit impedance Ro is Represents the voltage associated with the ohmic impedance, and the voltage division of the polarization resistor Rep is Represents the voltage associated with electrochemical polarization.

[0073] In this embodiment, an initial model of the open circuit voltage is obtained according to the dynamic voltage equivalent circuit, including: according to the dynamic voltage equivalent circuit, respectively obtaining the voltage division of the open circuit voltage source, the voltage division of the circuit impedance and the voltage division of the polarization resistance, the open circuit voltage is the voltage division of the open circuit voltage source; according to the voltage division of the open circuit voltage source, the voltage division of the circuit impedance and the voltage division of the polarization resistance, generating an initial model of the open circuit voltage.

[0074] Specifically, according to the dynamic voltage equivalent circuit model of the battery, the following formula can be known:

[0075]

[0076] represents dynamic voltage, OCV represents open circuit voltage, represents the voltage associated with ohmic impedance, , is a fixed value, Mainly affected by the current I, represents the voltage associated with electrochemical polarization, Affected by SOC, temperature T, current I, depth of discharge DOD, etc., SOC and OCV have a relationship .

[0077] Then formula 1 can be rewritten as:

[0078] (Formula 2)

[0079] The static open circuit voltage of the battery device when it is at rest (static ) and the dynamic voltage during charge and discharge. Figure 3 As shown by Figure 3 It can be seen that static It is approximately linear with the dynamic voltage.

[0080] Assuming that the solid phase diffusion coefficient (which affects the charge and discharge performance of the battery) remains unchanged, the pressure difference caused by solid phase diffusion is proportional to OCV. Assuming that the solid phase diffusion coefficient remains unchanged at low SOC (such as below 30% SOC), It can be represented as ( 1), then formula 2 can be expressed as the following formula 3:

[0081]

[0082] (Formula 3)

[0083] From formula 3, we can see that and There is a linear relationship between them.

[0084] Then we can get the value according to formula 3 , which can be simplified to y = kx + b. In an ideal situation, without considering the polarization effects of temperature, rate, and discharge depth, according to 1, the parameters of the open circuit voltage model are Depend on get.

[0085] That is to say, the initial model of the open circuit voltage model is y=kx + b, where y represents the open circuit voltage, x represents the dynamic voltage, and k and b are constant coefficients.

[0086] It can be seen from the above embodiments that the open circuit voltage model of this embodiment is obtained based on the dynamic voltage equivalent circuit model of the battery, has reliable theoretical support and high accuracy.

[0087] It should be noted that, considering the polarization effects of temperature, rate, and discharge depth, according to get.

[0088] Therefore, in an embodiment of the present application, an initial model of the open circuit voltage is generated based on the voltage division of the open circuit voltage source, the voltage division of the circuit impedance, and the voltage division of the polarization resistor, and it also includes: generating an initial model of the open circuit voltage based on the voltage division of the open circuit voltage source, the voltage division of the circuit impedance, the voltage division of the polarization resistor, and preset influencing parameters of the voltage division of the polarization resistor; the preset influencing parameters include one or more of the battery state of charge SOC, temperature T, current I, and depth of discharge DOD of the battery device.

[0089] That is, in the process of calculating the initial model, ( ) as the value for calculating b.

[0090] That is to say, taking into account the polarization effects of temperature, rate, and discharge depth, this embodiment uses the dynamic voltage of the battery device, the open circuit voltage of the battery device, the battery temperature, the impedance voltage of the battery, the discharge depth, and the polarization voltage as battery state data for fitting to obtain the values ​​of the constant coefficients in the initial model.

[0091] In this way, the effects of battery temperature, battery impedance voltage, discharge depth and polarization voltage on the open circuit voltage can be taken into account, thereby improving the accuracy of the open circuit voltage model.

[0092] In an embodiment of the present application, collecting battery status data of a battery device includes: extracting discharge condition data from historical charge and discharge data of the battery device; screening out spare data in which the standing time at the end of discharge is greater than a preset time from the discharge condition data; and obtaining battery status data based on the spare data.

[0093] The historical charge and discharge data of the battery may include parameters such as time, voltage, current, SOC, and charge and discharge flags.

[0094] It is understandable that polarization will occur inside the battery during the charging process, which makes the relationship between voltage and actual SOC complicated. Therefore, this embodiment selects discharge condition data. During the discharge process, the battery can measure a more stable open circuit voltage after being stationary for a period of time. The discharge data can better reflect the dynamic characteristics and internal state changes of the battery, thereby improving the reliability of the model, which is helpful for accurately estimating SOC.

[0095] In one example, the preset duration can be customized according to the actual vehicle operating conditions. The preset duration is, for example, 1 hour, 2 hours, 3 hours, etc., which are not listed here one by one.

[0096] After the discharge is completed, the battery device is not connected to any load and is left to rest for a certain period of time. This time is the resting time at the end of the discharge. The purpose of resting is to allow the electrochemical reaction inside the battery to stabilize in order to obtain an accurate open circuit voltage (OCV).

[0097] The dynamic voltage at the end of discharge refers to the voltage measured at the last moment before the battery is discharged and left to rest. This voltage reflects the dynamic voltage state of the battery during the discharge process.

[0098] This embodiment selects spare data in which the standing time at the end of discharge is greater than the preset time from the discharge condition data. The open circuit voltage in the spare data tends to be stable, and the battery status data obtained based on the spare data is more consistent with the actual working conditions, which can improve the reliability of the model.

[0099] In an embodiment of the present application, battery status data is obtained based on backup data, including: for each operating condition in the backup data, the battery static voltage at the discharge end corresponding to each operating condition is used as the open circuit voltage, and the dynamic voltage at the discharge end corresponding to each operating condition is used as the dynamic voltage, as a set of status data, to obtain multiple sets of status data; battery status data is obtained based on the multiple sets of status data.

[0100] In an example, taking the preset duration as 1 hour, multiple discharge conditions with a static duration greater than 1 hour can be obtained, and the data can be optimized by removing null values, duplicate rows, and abnormal value data. Then, the static voltage at the discharge end corresponding to the discharge condition with a static duration greater than 1 hour (which can represent the open circuit voltage OCV) and the dynamic voltage at the discharge end (the voltage before static, which can represent the dynamic voltage ), so that the dynamic voltage at the discharge end corresponding to each working condition is taken as the dynamic voltage and as a set of state data, multiple sets of OCV and , according to the OCV and Get battery status data.

[0101] The static voltage and dynamic voltage in the battery status data obtained in the above manner in this embodiment are obtained based on historical actual operating condition data. The open circuit voltage model is fitted using the battery status data to improve the model accuracy.

[0102] In an embodiment of the present application, the battery status data is obtained according to multiple groups of status data, including: according to the current at the end of discharge being within a preset current range, the multiple groups of status data are screened to obtain the battery status data.

[0103] It can be seen from the above embodiments that represents the voltage associated with ohmic impedance, Mainly affected by the current I, the larger the current value, the greater the polarization, therefore, this embodiment screens multiple groups of state data by a preset current interval. In one example, the preset current interval may be ±3A.

[0104] This can reduce the impact of ohmic polarization caused by current on the accuracy of the open circuit voltage model.

[0105] In an embodiment of the present application, based on the initial model, the battery status data is fitted to obtain the values ​​of the constant coefficients in the initial model, including: based on the initial model, the battery status data is fitted to obtain multiple fitted open circuit voltage curves; based on the open circuit voltage and the dynamic voltage, the real open circuit voltage curve of the battery device is obtained; among the multiple fitted open circuit voltage curves, a fitted open circuit voltage curve with the smallest error with the real open circuit voltage curve is obtained as a target curve; the values ​​of the constant coefficients in the target curve are obtained as the values ​​of the constant coefficients in the initial model.

[0106] The battery status data obtained using the above method is used to obtain multiple possible open circuit voltage curves, which represent the performance of the model under different parameter settings. Taking the preset duration of 1 hour as an example, the static duration of the battery in the discharge data can be 2 hours, 3 hours, 4 hours, etc. In this embodiment, multiple fitted open circuit voltage curves can be obtained by selecting battery status data greater than or equal to 1 hour and less than 3 hours, so that the fitted data covers different states of the battery during the static process. Such data is more representative, improves the stability, representativeness and quality of the data, and reduces the impact of extreme situations.

[0107] The real open circuit voltage curve of the battery device is obtained based on the open circuit voltage and the dynamic voltage. The real open circuit voltage curve of the battery device can be obtained by using battery status data with a longer static time. For example, the real open circuit voltage curve of the battery device can be obtained by selecting battery status data of more than 3 hours, which can reflect the stability and aging characteristics of the battery over a longer period of time.

[0108] For each fitted open circuit voltage curve, calculate the error between it and the true open circuit voltage curve. From multiple fitted curves, select the one with the smallest error with the true open circuit voltage curve as the target curve. This can be achieved through a variety of error metrics, such as mean square error (MSE), mean absolute error (MAE), or root mean square error (RMSE).

[0109] The above steps of obtaining a plurality of fitting voltage curves and the actual open-circuit voltage curves of the battery cell may be performed simultaneously, or may be performed sequentially in a preset order, which is not particularly limited in the embodiment of the present invention.

[0110] Figure 4 A target curve effect diagram of this embodiment is shown, such as Figure 4 As shown in the figure, the initial parameters a and b of the open circuit voltage model obtained by the above method are 0.9418 and 0.1897, that is, y=0.9418x + 0.1897. Figure 4 It can be seen that R 2 =0.9467, R 2 is the coefficient of determination, and the coefficient of determination is close to 1, which indicates that the predicted value of the model is basically equal to the observed value, with a small error and good prediction accuracy. In other words, the above model y=0.9418x + 0.1897 can be used as the final open circuit voltage model.

[0111] By fitting the battery status data, the embodiment of the present application can make the model more accurately reflect the actual behavior of the battery, make the model more accurately describe the dynamic and static characteristics of the battery, improve the accuracy of the model prediction, and obtain a more accurate open circuit voltage, so as to more accurately estimate the SOC of the battery device.

[0112] After obtaining the open circuit voltage model, the SOC prediction value can be obtained by querying the SOC_OCV mapping table through the open circuit voltage value output by the voltage prediction model. The accuracy of the open circuit voltage model can be further verified by comparing the error between the SOC prediction value and the SOC true value.

[0113] Figure 5 The error distribution diagram of the dynamic SOC obtained in this embodiment is shown. Figure 5 It can be seen that the dynamic SOC errors of this embodiment are all distributed within ±3%, with high accuracy, which further illustrates that the open circuit voltage model obtained in the above manner of this embodiment has high accuracy.

[0114] The embodiment of the present application provides an open circuit voltage model generation method, through which an open circuit voltage model that can characterize the relationship between dynamic voltage and open circuit voltage is obtained, wherein the open circuit voltage model is obtained based on an equivalent circuit model, so that the open circuit voltage model has reliable mechanism support and strong theoretical explanatory power. The open circuit voltage model is also driven by battery status data, which can improve the accuracy of the model, realize real-time prediction of open circuit voltage, and is simple to calculate without complex decoupling and more calculations.

[0115] The present application provides a method for estimating a state of charge. Figure 6 A flow chart showing the steps of a method for estimating a state of charge provided by an embodiment of the present application is shown. Figure 6 , the method comprising:

[0116] S601: Collect battery status data of a battery device.

[0117] Battery status data includes real-time dynamic voltage. Specific battery status data can be collected through the vehicle's BMS system. Battery status data may include the dynamic voltage and open circuit voltage of the battery under different charge and discharge states. It should be noted that in the actual implementation of this solution, some working data related to the properties of the battery cell itself can also be collected at the same time. For example, the current value, operating temperature, charge and discharge rate, charge and discharge depth, internal resistance, time series data, etc. of the battery device. Time series data may include recording changes in battery status over time, including voltage changes in different stages such as static, charge and discharge, which helps capture dynamic changes in battery performance.

[0118] S602: Based on the battery status data, an open circuit voltage model is used to obtain an open circuit voltage of the battery device.

[0119] The open circuit voltage model is a model obtained by using any of the open circuit voltage model generation methods in the above embodiments, such as the open circuit voltage model generation method described in steps S101 to S105, which is not described here for ease of reading. The real-time dynamic voltage of the battery status data is used as the input of the open circuit voltage model to output the open circuit voltage.

[0120] S603 , obtaining the battery state of charge of the battery device by using the open circuit voltage and the corresponding relationship between the preset open circuit voltage and the battery state of charge.

[0121] In this embodiment, the preset correspondence between the open circuit voltage and the battery state of charge, namely the SOC_OCV mapping table, can obtain the SOC value corresponding to the dynamic open circuit voltage OCV, namely the dynamic SOC.

[0122] The open circuit voltage model generation method and the state of charge estimation method provided in the present application are described below with a specific embodiment.

[0123] S1. Construct an open circuit voltage model.

[0124] Open Circuit Voltage Initial Model , which can be simplified to y=kx + b, where y represents the open circuit voltage and x represents the dynamic voltage.

[0125] S2. Obtain historical data.

[0126] Obtain the historical operation data of a vehicle in a project, and perform preprocessing to remove null values, duplicate rows, and abnormal value data. The column names of the historical operation data include time, voltage, current, SOC, charge and discharge flags, and obtain the SOC_OCV mapping relationship table of the project.

[0127] S3. Obtain battery status data.

[0128] Extract the discharge segment according to the charge and discharge flag, and record the start time, end time, static time at the end of the discharge, static voltage at the end of the discharge (which can represent the open circuit voltage OCV), and dynamic voltage at the end of the discharge (voltage before static, which can represent the dynamic voltage) of each discharge segment that meets the conditions. According to the discharge condition where the static time is greater than 1 hour and the current at the end of the discharge is within ±3A, the static voltage (open circuit voltage OCV) at the end of the discharge and the dynamic voltage (dynamic voltage) at the end of the discharge are calculated. ), get the battery status data.

[0129] S4. Perform fitting processing on the battery status data.

[0130] The battery status data of the static voltage at the end of discharge with a static time of >= 1h and a static time of <3h at the end of discharge are selected as the training set, and the relationship between static OCV and dynamic voltage is fitted to obtain the slope k and intercept b. The battery status data of the static time at the end of discharge with a static time of >= 3h are selected as the verification set. The verification results are as follows: Figure 4 As shown, determine the values ​​of the slope k and the intercept b in y=kx + b, that is, determine the open circuit voltage model.

[0131] S5. Battery state of charge estimation.

[0132] Obtain real-time dynamic voltage during battery charging and discharging ,according to And y=kx+ b, you can get the value of y, that is, the dynamic open circuit voltage OCV, and then query the SOC_OCV mapping table to get the SOC value corresponding to the dynamic open circuit voltage OCV, that is, the dynamic SOC.

[0133] The present application embodiment provides an open circuit voltage model generation device, Figure 7A schematic diagram of the structure of an open circuit voltage model generation device provided in an embodiment of the present application is shown. Figure 7 As shown, the open circuit voltage model generating device 500 includes:

[0134] The first acquisition module 501 is used to acquire a dynamic voltage equivalent circuit of a battery device.

[0135] The model creation module 502 is used to obtain an initial model of the open circuit voltage according to the dynamic voltage equivalent circuit, wherein the initial model includes constant coefficients of unknown values.

[0136] The second acquisition module 503 is used to collect battery status data of the battery device, where the battery status data includes an open circuit voltage and a dynamic voltage.

[0137] The data processing module 504 is used to perform fitting processing on the battery status data based on the initial model to obtain the values ​​of the constant coefficients in the initial model.

[0138] The model determination module 505 is used to determine the open circuit voltage model according to the values ​​of the constant coefficients and the initial model, and the open circuit voltage model is used to characterize the relationship between the dynamic voltage and the open circuit voltage.

[0139] In one example, the dynamic voltage equivalent circuit includes an open circuit voltage source, a circuit impedance and a polarization resistor connected in series; the model creation module 502 is also used to obtain the voltage division of the open circuit voltage source, the voltage division of the circuit impedance and the voltage division of the polarization resistor according to the dynamic voltage equivalent circuit, and the open circuit voltage is the voltage division of the open circuit voltage source; based on the voltage division of the open circuit voltage source, the voltage division of the circuit impedance and the voltage division of the polarization resistor, an initial model of the open circuit voltage is generated.

[0140] In one example, the model creation module 502 is also used to generate an initial model of the open circuit voltage based on the voltage division of the open circuit voltage source, the voltage division of the circuit impedance, the voltage division of the polarization resistance, and preset influencing parameters of the voltage division of the polarization resistance; the preset influencing parameters include one or more of the battery state of charge, temperature, current, and discharge depth of the battery device.

[0141] In one example, the second acquisition module 503 is also used to extract discharge condition data from the historical charge and discharge data of the battery device; filter out spare data whose standing time at the end of discharge is greater than a preset time from the discharge condition data; and obtain the battery status data based on the spare data.

[0142] In one example, the second acquisition module 503 is also used to, for each operating condition in the backup data, use the battery static voltage at the discharge end corresponding to each operating condition as the open circuit voltage, and use the dynamic voltage at the discharge end corresponding to each operating condition as the dynamic voltage, as a set of status data to obtain multiple sets of status data; and obtain the battery status data based on the multiple sets of status data.

[0143] In an example, the second acquisition module 503 is further configured to filter the multiple groups of status data according to whether the current at the end of discharge is within a preset current range to obtain the battery status data.

[0144] In one example, the data processing module 504 is used to fit the battery status data based on the initial model to obtain multiple fitted open circuit voltage curves; obtain the real open circuit voltage curve of the battery device according to the open circuit voltage and the dynamic voltage; among the multiple fitted open circuit voltage curves, obtain a fitted open circuit voltage curve with the smallest error with the real open circuit voltage curve as a target curve; obtain the numerical value of each constant coefficient in the target curve as the numerical value of each constant coefficient in the initial model.

[0145] The open circuit voltage model generation device provided in the above-mentioned embodiment of the present application and the open circuit voltage model generation method provided in the embodiment of the present application are based on the same application concept and have the same beneficial effects as the methods adopted, run or implemented by the application programs stored therein.

[0146] The present application provides a device for estimating a state of charge. Figure 8 A schematic diagram of the structure of a charge state estimation device provided in an embodiment of the present application is shown. Figure 8 As shown, the charge state estimation device 600 includes:

[0147] The collecting unit 601 is used to collect the battery status data of the battery device, wherein the battery status data includes: open circuit voltage and real-time dynamic voltage;

[0148] The open circuit voltage calculation unit 602 is used to obtain the open circuit voltage of the battery device based on the battery status data using an open circuit voltage model; the open circuit voltage model is a model obtained using the open circuit voltage model generation method described in the above embodiment.

[0149] The estimation unit 603 is used to obtain the battery state of charge of the battery device by using the open circuit voltage and the corresponding relationship between the preset open circuit voltage and the battery state of charge.

[0150] The state of charge estimation device provided in the above-mentioned embodiment of the present application and the state of charge estimation method provided in the embodiment of the present application are based on the same application concept and have the same beneficial effects as the methods adopted, run or implemented by the application programs stored therein.

[0151] Please refer to Fig. 9 , which shows a schematic diagram of an electronic device provided by some embodiments of the present application. Fig. 9 As shown, the electronic device 20 includes: a processor 200, a memory 201, a bus 202 and a communication interface 203, and the processor 200, the communication interface 203 and the memory 201 are connected via the bus 202; the memory 201 stores a computer program that can be run on the processor 200, and the processor 200 executes the method provided in any of the aforementioned embodiments of the present application when running the computer program.

[0152] The memory 201 may include a high-speed random access memory (RAM), and may also include a non-volatile memory, such as at least one disk memory. The communication connection between the system network element and at least one other network element is realized through at least one communication interface 203 (which may be wired or wireless), and the Internet, wide area network, local area network, metropolitan area network, etc. may be used.

[0153] The bus 202 may be an ISA bus, a PCI bus, or an EISA bus, etc. The bus may be divided into an address bus, a data bus, a control bus, etc. The memory 201 is used to store a program, and the processor 200 executes the program after receiving an execution instruction. The method for estimating the state of charge of the battery device disclosed in any of the embodiments of the present application may be applied to the processor 200, or implemented by the processor 200.

[0154] The processor 200 may be an integrated circuit chip with signal processing capabilities. In the implementation process, each step of the above method can be completed by the hardware integrated logic circuit or software instructions in the processor 200. The above processor 200 can be a general-purpose processor, including a central processing unit (CPU), a network processor (NP), etc.; it can also be a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a readily available programmable gate array (FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components. The methods, steps and logic block diagrams disclosed in the embodiments of the present application can be implemented or executed. The general-purpose processor can be a microprocessor or the processor can also be any conventional processor, etc. The steps of the method disclosed in the embodiments of the present application can be directly embodied as a hardware decoding processor to be executed, or the hardware and software modules in the decoding processor can be executed. The software module can be located in a mature storage medium in the field such as a random access memory, a flash memory, a read-only memory, a programmable read-only memory or an electrically erasable programmable memory, a register, etc. The storage medium is located in the memory 201, and the processor 200 reads the information in the memory 201 and completes the steps of the above method in combination with its hardware.

[0155] The electronic device provided in the embodiment of the present application and the open circuit voltage model generation method provided in the embodiment of the present application are based on the same application concept and have the same beneficial effects as the methods adopted, operated or implemented therein.

[0156] The present application also provides a computer-readable storage medium corresponding to the open circuit voltage model generation method and the charge state estimation method provided in the above-mentioned embodiment. Fig.10 , which shows a computer-readable storage medium 30, which may be a CD, on which a program product is stored, which may be an operating system, application software, game, tool software, etc. The program product includes a computer program, which is usually in the form of source code or compiled binary. When the computer program is run by a processor, it will execute the charge state estimation method of the battery device provided in any of the aforementioned embodiments.

[0157] It should be noted that examples of the computer-readable storage medium may also include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other optical or magnetic storage media, which are not listed here one by one.

[0158] The computer-readable storage medium provided in the above-mentioned embodiments of the present application and the open circuit voltage model generation method and the state of charge estimation method provided in the embodiments of the present application are based on the same application concept and have the same beneficial effects as the methods adopted, run or implemented by the application programs stored therein.

[0159] It should be noted that:

[0160] In the above text, the term "comprises", "includes" or any other variant thereof is intended to cover non-exclusive inclusion, so that the process, method, article or device including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "including one..." do not exclude the presence of other identical elements in the process, method, article or device including the element. In addition, it should be noted that the scope of the method and device in the embodiment of the present application is not limited to performing functions in the order shown or discussed, and may also include performing functions in a substantially simultaneous manner or in reverse order according to the functions involved, for example, the described method may be performed in an order different from that described, and various steps may also be added, omitted, or combined. In addition, the features described with reference to certain examples may be combined in other examples.

[0161] Through the description of the above implementation methods, those skilled in the art can clearly understand that the above-mentioned embodiment methods can be implemented by means of software plus a necessary general hardware platform, and of course by hardware, but in many cases the former is a better implementation method. Based on such an understanding, the technical solution of the present application, or the part that contributes to the prior art, can be embodied in the form of a software product, which is stored in a storage medium (such as ROM / RAM, a magnetic disk, or an optical disk), and includes a number of instructions for a terminal (which can be a mobile phone, a computer, a server, an air conditioner, or a network device, etc.) to execute the methods described in each embodiment of the present application.

[0162] The embodiments of the present application are described above in conjunction with the accompanying drawings, which are only specific implementation modes of the present application. However, the present application is not limited to the above-mentioned specific implementation modes. The above-mentioned specific implementation modes are merely illustrative and not restrictive. Under the guidance of the present application, ordinary technicians in this field can also make many forms without departing from the purpose of the present application and the scope of protection of the claims, all of which are within the protection of the present application.

Claims

1. A method for generating an open circuit voltage model, characterized in that: The method comprises: Obtaining a dynamic voltage equivalent circuit of a battery device; According to the dynamic voltage equivalent circuit, an initial model of the open circuit voltage is obtained, wherein the initial model includes constant coefficients of unknown values; Collecting battery status data of the battery device, the battery status data including open circuit voltage and dynamic voltage, the battery status data being obtained by screening discharge operating condition data in historical charge and discharge data; Based on the initial model, fitting processing is performed on the battery state data to obtain the values ​​of the constant coefficients in the initial model; The open circuit voltage model is determined according to the values ​​of the constant coefficients and the initial model, and the open circuit voltage model is used to characterize the relationship between the dynamic voltage and the open circuit voltage.

2. The method according to claim 1, characterized in that The dynamic voltage equivalent circuit includes an open circuit voltage source, a circuit impedance and a polarization resistance connected in series; and according to the dynamic voltage equivalent circuit, an initial model of the open circuit voltage is obtained, including: According to the dynamic voltage equivalent circuit, respectively obtaining the divided voltage of the open circuit voltage source, the divided voltage of the circuit impedance and the divided voltage of the polarization resistor, the open circuit voltage being the divided voltage of the open circuit voltage source; An initial model of the open circuit voltage is generated according to the divided voltage of the open circuit voltage source, the divided voltage of the circuit impedance, and the divided voltage of the polarization resistance.

3. The method according to claim 2, characterized in that Generating an initial model of the open circuit voltage according to the divided voltage of the open circuit voltage source, the divided voltage of the circuit impedance, and the divided voltage of the polarization resistor, further comprising: Generate an initial model of the open circuit voltage according to the divided voltage of the open circuit voltage source, the divided voltage of the circuit impedance, the divided voltage of the polarization resistor, and preset influencing parameters of the divided voltage of the polarization resistor; The preset influencing parameters include one or more of the battery state of charge, temperature, current, and discharge depth of the battery device.

4. The method according to claim 1, characterized in that Collecting battery status data of the battery device includes: Extracting discharge condition data from historical charge and discharge data of the battery device; Filter out spare data whose static time at the discharge end is longer than a preset time from the discharge condition data; The battery status data is obtained according to the backup data.

5. The method according to claim 4, characterized in that Obtaining the battery status data according to the backup data includes: For each operating condition in the backup data, the static voltage of the battery at the discharge end corresponding to each operating condition is used as the open circuit voltage, and the dynamic voltage at the discharge end corresponding to each operating condition is used as the dynamic voltage, as a set of state data, to obtain multiple sets of state data; The battery status data is obtained according to the multiple groups of status data.

6. The method according to claim 5, characterized in that Obtaining the battery status data according to the multiple groups of status data includes: According to the current at the end of discharge being within a preset current range, the multiple groups of status data are screened to obtain the battery status data.

7. The method according to claim 1, characterized in that Based on the initial model, the battery state data is fitted to obtain the values ​​of the constant coefficients in the initial model, including: Based on the initial model, fitting the battery state data to obtain a plurality of fitting open circuit voltage curves; Acquiring a real open circuit voltage curve of the battery device according to the open circuit voltage and the dynamic voltage; Among multiple fitted open-circuit voltage curves, a fitted open-circuit voltage curve having the smallest error with the real open-circuit voltage curve is obtained as a target curve; The values ​​of the constant coefficients in the target curve are obtained as the values ​​of the constant coefficients in the initial model.

8. A method for estimating a state of charge, characterized in that: The method comprises: Collecting battery status data of the battery device, wherein the battery status data includes real-time dynamic voltage; Based on the battery status data, an open circuit voltage of the battery device is obtained using an open circuit voltage model; the open circuit voltage model is a model obtained using the open circuit voltage model generation method according to any one of claims 1 to 7; The battery state of charge of the battery device is obtained by using the open circuit voltage and the corresponding relationship between the preset open circuit voltage and the battery state of charge.

9. An open circuit voltage model generating device, characterized in that: The device comprises: A first acquisition module, used to acquire a dynamic voltage equivalent circuit of a battery device; A model creation module, used to obtain an initial model of the open circuit voltage according to the dynamic voltage equivalent circuit, wherein the initial model contains constant coefficients of unknown values; A second acquisition module, used for collecting battery status data of the battery device, wherein the battery status data includes an open circuit voltage and a dynamic voltage; A data processing module, used for performing fitting processing on the battery state data based on the initial model to obtain the values ​​of the constant coefficients in the initial model; The model determination module is used to determine the open circuit voltage model according to the values ​​of the constant coefficients and the initial model, and the open circuit voltage model is used to characterize the relationship between the dynamic voltage and the open circuit voltage.

10. A state of charge estimation device, characterized in that: The device comprises: A collection unit, used to collect battery status data of the battery device, wherein the battery status data includes: open circuit voltage and real-time dynamic voltage; an open circuit voltage calculation unit, configured to obtain the open circuit voltage of the battery device based on the battery status data and using an open circuit voltage model; the open circuit voltage model is a model obtained by using the open circuit voltage model generation method according to any one of claims 1 to 7; The estimation unit is used to obtain the battery state of charge of the battery device by using the open circuit voltage and a corresponding relationship between the preset open circuit voltage and the battery state of charge.

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