Battery equivalent circuit model establishment method, device and equipment and readable storage medium

Abstract

The application discloses a battery equivalent circuit model establishing method, device and equipment and a readable storage medium, relates to the technical field of battery management, and comprises the following steps: obtaining positive half-cell impedance spectroscopy and negative half-cell impedance spectroscopy obtained by performing electrochemical impedance spectroscopy test under a battery three-electrode system; dividing a frequency range into different frequency bands according to the positive half-cell impedance spectroscopy and the negative half-cell impedance spectroscopy, and configuring different equivalent impedance models for the different frequency bands; obtaining a battery working frequency, and selecting a positive half-cell equivalent impedance model and a negative half-cell equivalent impedance model according to a frequency band in which the battery working frequency is located; superimposing the selected positive half-cell equivalent impedance model and the negative half-cell equivalent impedance model to obtain a full-cell equivalent impedance model, and then establishing a battery equivalent circuit model according to the full-cell equivalent impedance model. The battery equivalent circuit model established by the application can balance high-frequency dynamic response and low-frequency steady-state accuracy in a wide frequency range.

Description

Technical Field

[0001] This invention relates to the field of battery management technology, and in particular to a method, apparatus, device, and readable storage medium for establishing a battery equivalent circuit model. Background Technology

[0002] As the core power source for new energy vehicles and energy storage systems, the accuracy of state estimation of lithium-ion batteries directly affects the safety and operating efficiency of the system. The equivalent circuit model (ECM) is widely used in battery management systems (BMS) due to its simple mathematical form, clear physical meaning of parameters, and ease of implementation in embedded systems.

[0003] In existing technologies, equivalent circuit models with fixed structures are commonly used to describe the external characteristics of batteries, such as the classic Thevenin model, the PNGV model, or a fixed-order RC network model. These models are typically based on full-cell electrochemical impedance spectroscopy (EIS) data or pulse charge-discharge test data for parameter identification, aiming to simulate the battery's ohmic internal resistance, polarization internal resistance, and open-circuit voltage characteristics through combinations of components such as resistors and capacitors.

[0004] However, as battery applications become increasingly complex, the aforementioned fixed structure model has gradually revealed its limitations. It is difficult to simultaneously achieve high-frequency dynamic response and low-frequency process accuracy. Often, high-frequency characteristics are sacrificed in order to ensure low-frequency accuracy, or vice versa. Summary of the Invention

[0005] This invention provides a method, apparatus, device, and readable storage medium for establishing a battery equivalent circuit model, in order to solve the technical problem in the related art that existing battery equivalent circuit models using fixed structure models cannot simultaneously take into account high-frequency dynamic response and low-frequency process accuracy.

[0006] Firstly, a method for establishing a battery equivalent circuit model is provided, including the following steps: Obtain the impedance spectra of the positive half-cell and the negative half-cell obtained by electrochemical impedance spectroscopy in a three-electrode battery system; Based on the impedance spectra of the positive and negative half-cell cells, the frequency range is divided into different frequency bands, and different equivalent impedance models are configured for different frequency bands. Obtain the battery operating frequency, and select the equivalent impedance model for the positive half-cell and the equivalent impedance model for the negative half-cell according to the frequency band in which the battery operating frequency is located. The equivalent impedance models of the selected positive half-cell and negative half-cell are superimposed to obtain the equivalent impedance model of the full cell. Then, the equivalent circuit model of the battery is established based on the equivalent impedance model of the full cell.

[0007] In some embodiments, the step of dividing the frequency range into multiple different frequency bands based on the impedance spectrum of the positive half-cell and configuring different equivalent impedance models for different frequency bands includes: The first frequency threshold, the second frequency threshold, and the third frequency threshold are determined based on the impedance spectrum of the positive half-cell; wherein, the first frequency threshold > the second frequency threshold > the third frequency threshold; The frequency range is divided into the following categories based on the first frequency threshold, the second frequency threshold, and the third frequency threshold: high frequency band above the first frequency threshold; mid-to-high frequency band between the first and second frequency thresholds; mid-to-low frequency band between the second and third frequency thresholds; and low frequency band below the third frequency threshold.

[0008] In some embodiments, the step of dividing the frequency range into multiple different frequency bands based on the impedance spectrum of the positive half-cell and configuring different equivalent impedance models for different frequency bands further includes: A first model containing inductive and ohmic resistor elements is configured in the high-frequency band. A second model is configured in the mid-to-high frequency band, comprising inductor elements, ohmic resistor elements, and at least one parallel RC unit. A third model is configured in the low-to-mid frequency band, which includes ohmic resistors and at least one parallel RC unit. A fourth model is configured in the low-frequency band, which includes ohmic resistor elements and at least two parallel RC units.

[0009] In some embodiments, determining the first frequency threshold, the second frequency threshold, and the third frequency threshold based on the impedance spectrum of the positive half-cell includes: The interpolation point between the two points where the sign of the imaginary part of the impedance spectrum of the positive half-cell is switched is used as the first frequency threshold. The frequency corresponding to the semicircular peak point in the impedance spectrum of the positive half-cell is used as the second frequency threshold. The data in the impedance spectrum of the positive half-cell that are below the second frequency threshold are compared with the preset detection data, and the frequency corresponding to the relative error exceeding the preset error threshold is taken as the third frequency threshold.

[0010] In some embodiments, the preset error threshold is set between 3% and 5%.

[0011] In some embodiments, obtaining the impedance spectra of the positive half-cell and the negative half-cell obtained by electrochemical impedance spectroscopy testing in a three-electrode battery system further includes: Establish a fitted equivalent impedance model using inductor elements, ohmic resistor elements, and at least two parallel RC units; The impedance spectra of the positive and negative half-cells were fitted based on the fitted equivalent impedance model.

[0012] In some embodiments, after superimposing the selected positive half-cell equivalent impedance model and the negative half-cell equivalent impedance model to obtain the full-cell equivalent impedance model, the method further includes: Obtain the impedance spectrum of the full cell obtained by electrochemical impedance spectroscopy in a three-electrode battery system; The obtained full-cell impedance spectrum was used to verify the superimposed full-cell equivalent impedance model.

[0013] Secondly, a device for establishing a battery equivalent circuit model is provided, comprising: The acquisition unit is used to acquire the impedance spectra of the positive half-cell and the negative half-cell obtained by electrochemical impedance spectroscopy testing in a three-electrode battery system. The division unit is used to divide the frequency range into different frequency bands according to the impedance spectrum of the positive half-cell and the impedance spectrum of the negative half-cell, and to configure different equivalent impedance models for different frequency bands. Select a unit to obtain the battery operating frequency, and select the equivalent impedance model of the positive half-cell and the equivalent impedance model of the negative half-cell according to the frequency band where the battery operating frequency is located. A unit is established to superimpose the selected positive half-cell equivalent impedance model and the negative half-cell equivalent impedance model to obtain the full-cell equivalent impedance model, and then establish the battery equivalent circuit model based on the full-cell equivalent impedance model.

[0014] Thirdly, a computer device is provided, comprising: a memory and a processor, wherein the memory stores at least one instruction, the at least one instruction being loaded and executed by the processor to implement the aforementioned method for establishing a battery equivalent circuit model.

[0015] Fourthly, a computer-readable storage medium is provided, the computer-readable storage medium storing computer instructions, which, when executed by a computer, cause the computer to perform the aforementioned method for establishing a battery equivalent circuit model.

[0016] The beneficial effects of the technical solution provided by this invention include: This invention provides a method, apparatus, device, and readable storage medium for establishing a battery equivalent circuit model. The method divides the frequency range into different frequency bands based on the impedance spectra of the positive and negative half-cells and configures different equivalent impedance models for different frequency bands. This breaks the limitations of traditional fixed structure models. For the inductive effect in the high-frequency band, the charge transfer polarization in the mid-frequency band, and the ion diffusion process in the low-frequency band, the most suitable circuit structure is matched respectively. This avoids the problem of a single model ignoring inductance at high frequencies or underfitting at low frequencies, significantly improving the fitting accuracy of the model across the entire frequency range. It achieves high-precision modeling over a wide frequency range, while taking into account both high-frequency dynamic response and low-frequency process accuracy, thereby improving the accuracy of battery state estimation over a wide operating frequency range. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 A flowchart illustrating a method for establishing a battery equivalent circuit model according to an embodiment of the present invention; Figure 2 Provided for embodiments of the present invention Figure 1 The Nyquist plot obtained by performing electrochemical impedance spectroscopy in step S1 of the battery three-electrode system; Figure 3 Provided for embodiments of the present invention Figure 1 A flowchart illustrating step S2 in the implementation process; Figure 4 Provided for embodiments of the present invention Figure 1 Another flowchart illustrating step S2 in the implementation process; Figure 5 Provided for embodiments of the present invention Figure 1 A schematic diagram of the equivalent impedance model that fully considers the inductor, the ohmic resistor and the two parallel RC units in step S4 of the implementation process. Figure 6 A schematic diagram of the equivalent circuit model of a battery obtained by selecting a 290Ah lithium iron phosphate cell product, provided for an embodiment of the present invention; Figure 7 The embodiments of the present invention are based on Figure 6 The Nyquist plot of the battery equivalent circuit model was obtained by electrochemical impedance spectroscopy in a three-electrode battery system. Figure 8This is a schematic diagram of a battery equivalent circuit model building device provided in an embodiment of the present invention; Figure 9 This is a schematic diagram of the structure of a computer device provided in an embodiment of the present invention. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] This invention provides a method for establishing a battery equivalent circuit model, which can solve the technical problem that existing battery equivalent circuit models using fixed structure models cannot simultaneously take into account high-frequency dynamic response and low-frequency process accuracy.

[0021] See Figure 1 This invention provides a method for establishing a battery equivalent circuit model, including the following steps: Step S1: Obtain the impedance spectra of the positive and negative half-cells using electrochemical impedance spectroscopy (EIS) in a three-electrode battery system. Specifically, a three-electrode battery system is constructed, comprising a positive half-cell and a negative half-cell. EIS measurements are performed on all three cells using an electrochemical workstation to obtain the full-cell impedance spectrum, the positive half-cell impedance spectrum, and the negative half-cell impedance spectrum. (See [link to relevant documentation]). Figure 2 , Figure 2 The red line represents the Nyquist plot corresponding to the impedance spectrum of the positive half-cell (impedance spectroscopy EIS test performed on the positive electrode and the reference electrode), the blue line represents the Nyquist plot corresponding to the impedance spectrum of the negative half-cell (impedance spectroscopy EIS test performed on the negative electrode and the reference electrode), the green line represents the Nyquist plot corresponding to the impedance spectrum of the full cell (impedance spectroscopy EIS test performed on the positive electrode and the negative electrode), and the black line represents the Nyquist plot corresponding to the sum of the impedance spectra of the positive half-cell and the impedance spectra of the negative half-cell.

[0022] Step S2: Divide the frequency range into different frequency bands according to the impedance spectrum of the positive half-cell and the impedance spectrum of the negative half-cell, and configure different equivalent impedance models for different frequency bands.

[0023] Specifically, see Figure 3 The step of dividing the frequency range into multiple different frequency bands based on the corresponding impedance spectra of the positive and negative half-cells, and configuring different equivalent impedance models for different frequency bands, includes: Step S21: Determine the first frequency threshold based on the impedance spectrum of the positive half-cell. f1. Second frequency threshold f 2 and the third frequency threshold f 3; where the first frequency threshold f 1 > Second frequency threshold f 2 > Third frequency threshold f 3.

[0024] Step S22, based on the first frequency threshold f 1. Second frequency threshold f 2 and the third frequency threshold f 3. Divide the frequency range into: above the first frequency threshold f 1 in the high-frequency band; between the first frequency threshold f 1 and the second frequency threshold f The mid-to-high frequency range between 2 and 3; between the second frequency threshold. f 2 and the third frequency threshold f The mid-to-low frequency range between 3; below the third frequency threshold f 3 in the low-frequency band.

[0025] See Figure 4 The method of dividing the frequency range into multiple different frequency bands based on the impedance spectra of the positive and negative half-cells, and configuring different equivalent impedance models for different frequency bands, further includes: Step S23: Configure a first model containing inductive and ohmic resistor elements in the high-frequency band, where the battery charge transfer polarization and diffusion polarization are negligible, and use the LR model.

[0026] Step S24: Configure a second model in the mid-to-high frequency band, which includes an inductor, an ohmic resistor, and at least one parallel RC unit. At this time, the charge transfer impedance gradually increases, and the L+ first-order R / / CPE model is used.

[0027] Step S25: Configure a third model in the low-to-mid frequency band, which includes ohmic resistors and at least one parallel RC unit. At this point, charge transfer impedance has become the main component and inductance impedance is very small. Therefore, the inductance is cut off and a first-order R / / CPE model is used.

[0028] Step S26: Configure a fourth model in the low-frequency band, which includes ohmic resistor elements and at least two parallel RC units, so that the ion diffusion accumulation effect is more obvious at this time, and use the second-order R / / CPE model.

[0029] Similarly, the above process can be used to divide the frequency range into multiple different frequency bands based on the impedance spectrum of the negative half-cell, and different equivalent impedance models can be configured for different frequency bands.

[0030] Step S3: Obtain the battery operating frequency, and select the equivalent impedance model for the positive half-cell and the equivalent impedance model for the negative half-cell according to the frequency band in which the battery operating frequency is located. Specifically, the battery current signal can be collected, and the battery frequency in the current operating condition scenario can be extracted through signal processing technology, such as operating conditions requiring AC frequency conversion, such as bidirectional pulse heating or AC heating.

[0031] Step S4: The selected equivalent impedance models of the positive and negative half-cells are superimposed to obtain the equivalent impedance model of the full cell. Then, the equivalent circuit model of the battery is established based on the full cell equivalent impedance model. Specifically, the equivalent impedance models of the positive and negative half-cells at the same frequency are superimposed to obtain the equivalent impedance model of the full cell at that frequency. This is then combined with an open-circuit voltage (OCV) lookup table to form the battery equivalent circuit model. See [link to relevant documentation] Figure 5 , Figure 5 The left side of the middle section contains the open-circuit voltage lookup table. Figure 5 The right side of the middle section shows the equivalent impedance model that fully considers the inductive element, the ohmic resistive element, and the two parallel RC units. Figure 5 The red box on the right is the positive electrode, the yellow box is the reference electrode, and the blue box is the negative electrode.

[0032] In practical applications, a 290Ah lithium iron phosphate cell is selected to establish a three-electrode battery system. Following the steps described above, the first frequency threshold is obtained based on the impedance spectrum of the positive half-cell. f 1. Second frequency threshold f 2 and the third frequency threshold f The corresponding frequencies are 36.8170Hz, 3.9828Hz, and 1.0345Hz. Similarly, based on the impedance spectrum of the negative half-cell, the corresponding three frequency thresholds are 117.3000Hz, 0.7170Hz, and 0.3318Hz. Assuming the battery operating frequency is 100Hz, the corresponding equivalent impedance models for the positive and negative half-cells are the high-frequency model (LR model) and the mid-to-high-frequency model (LR + first-order R / / CPE model), respectively. The superimposed equivalent impedance model of the full cell is... Figure 5 The upper right half retains Lan and R0an, while the lower right half retains Lca, R0ca, R1ca, and CPE1ca. See details. Figure 6 The battery equivalent circuit model. Based on Figure 6 The battery equivalent circuit model was subjected to impedance spectroscopy (EIS) tests using an electrochemical workstation under the three-electrode battery theory system. (See [reference needed]). Figure 7 , Figure 7The red line represents the Nyquist plot corresponding to the impedance spectrum of the positive half-cell (impedance spectrum EIS test performed on the positive electrode and the reference electrode), the blue line represents the Nyquist plot corresponding to the impedance spectrum of the negative half-cell (impedance spectrum EIS test performed on the negative electrode and the reference electrode), the green line represents the Nyquist plot corresponding to the impedance spectrum of the full cell (impedance spectrum EIS test performed on the positive and negative electrodes), and the black line represents the Nyquist plot corresponding to the impedance spectrum of the full cell of the actual 290Ah lithium iron phosphate cell product (impedance spectrum EIS test performed on the positive and negative electrodes). By comparison (comparing green and black), it can be seen that the trend of the green curve conforms to the actual full cell impedance characteristics (black dot), that is, the modeling of the equivalent impedance model of lithium-ion battery is realized in a wide frequency range, and the model complexity is effectively reduced while ensuring the accuracy of the model.

[0033] In summary, the battery equivalent circuit model establishment method in this embodiment divides the frequency range into different frequency bands based on the impedance spectra of the positive and negative half-cells, and configures different equivalent impedance models for different frequency bands. This breaks the limitations of traditional fixed structure models. For the inductive effect in the high-frequency band, the charge transfer polarization in the mid-frequency band, and the ion diffusion process in the low-frequency band, the most suitable circuit structure is matched respectively. This avoids the problem of a single model ignoring inductance at high frequencies or insufficient fitting at low frequencies, significantly improving the fitting accuracy of the model across the entire frequency range, achieving high-precision modeling over a wide frequency range, and simultaneously taking into account both high-frequency dynamic response and low-frequency process accuracy. This is beneficial for improving the accuracy of battery state estimation over a wide operating frequency range.

[0034] In one embodiment, the determination of the first frequency threshold based on the impedance spectrum of the positive half-cell is... f 1. Second frequency threshold f 2 and the third frequency threshold f 3, including: The interpolation point between the two points where the sign of the imaginary part of the impedance spectrum of the positive half-cell changes is used as the first frequency threshold. f 1. f 1 corresponds to the imaginary zero-crossing point of the battery impedance when it exhibits purely resistive behavior, when the frequency is higher than... f At 1, the battery exhibits inductive characteristics; when the frequency is lower than 1, the battery exhibits inductive characteristics. f At 1, the battery exhibits capacitive characteristics. Therefore, f 1 is the dividing point between introducing an inductive element and not introducing an inductive element. Find two adjacent frequency points in the impedance spectrum of the positive half-cell where the imaginary part Z′′ changes from positive to negative, and calculate the zero-crossing frequency through linear interpolation.

[0035] The frequency corresponding to the semi-circular peak point in the impedance spectrum of the positive half-cell is used as the second frequency threshold. f 2, f 2 corresponds to the reciprocal of the time constant of the charge transfer process; near this frequency, the charge transfer impedance dominates. When the frequency is lower than...f At time 2, the inductive effect is usually negligible, and the inductive element can be cut off to simplify the model.

[0036] The impedance spectrum of the positive half-cell is below the second frequency threshold. f The data from step 2 is compared with the preset detection data, and the frequency at which the relative error exceeds the preset error threshold is taken as the third frequency threshold. f 3. f 3 corresponds to the frequency point at which the ion diffusion process begins to be significantly affected. Higher than [the specified frequency]. f At time 3, a first-order R / / CPE model is sufficient to meet the accuracy requirements; below that, a third-order model is sufficient. f At time 3, the diffusion effect intensifies, requiring a switch to a second-order R / / CPE model. The first-order R / / CPE model is then used to fit the low-frequency data, and the relative fitting error is monitored. When the error exceeds a preset error threshold (which can be between 3% and 5%), the frequency at that point is recorded. f 3. The preset detection data are full-cell impedance spectral data obtained by actual measurement using an electrochemical workstation, or standard impedance spectral data obtained based on standard battery samples.

[0037] In one embodiment, obtaining the impedance spectra of the positive half-cell and the impedance spectra of the negative half-cell obtained by electrochemical impedance spectroscopy testing in a three-electrode battery system further includes: Establish a fitted equivalent impedance model using inductor elements, ohmic resistor elements, and at least two parallel RC units; The impedance spectra of the positive and negative half-cells were fitted based on the fitted equivalent impedance model.

[0038] By fitting the impedance spectrum of the positive half-cell and the impedance spectrum of the negative half-cell with a fitting equivalent impedance model that fully considers the inductive element, the ohmic resistive element and at least two parallel RC units, the reliability of the data in the impedance spectrum of the positive half-cell and the impedance spectrum of the negative half-cell can be improved.

[0039] In one embodiment, after superimposing the selected positive half-cell equivalent impedance model and the negative half-cell equivalent impedance model to obtain the battery equivalent circuit model, the method further includes: Obtain the impedance spectrum of the full cell obtained by electrochemical impedance spectroscopy in a three-electrode battery system; The obtained full-cell impedance spectrum was used to verify the superimposed full-cell equivalent impedance model.

[0040] For example, similar Figure 7 In the process, by comparing the black dots (the impedance spectrum of the full cell) with the green curve (obtained by further impedance spectrum testing of the battery equivalent circuit model), the reliability of the superimposed full cell equivalent impedance model can be verified, ensuring the accuracy of the modeling results.

[0041] See Figure 8 As shown in the figure, this embodiment of the invention also provides a battery equivalent circuit model establishment device, including: an acquisition unit, a division unit, a selection unit, and an establishment unit.

[0042] The acquisition unit is used to acquire the impedance spectra of the positive half-cell and the impedance spectra of the negative half-cell obtained by electrochemical impedance spectroscopy testing in a three-electrode battery system.

[0043] The division unit is used to divide the frequency range into different frequency bands according to the impedance spectrum of the positive half-cell and the impedance spectrum of the negative half-cell, and to configure different equivalent impedance models for different frequency bands.

[0044] The selection unit is used to obtain the battery operating frequency and select the equivalent impedance model of the positive half-cell and the equivalent impedance model of the negative half-cell according to the frequency band where the battery operating frequency is located.

[0045] The establishment unit is used to superimpose the selected positive half-cell equivalent impedance model and negative half-cell equivalent impedance model to obtain the full-cell equivalent impedance model, and then establish the battery equivalent circuit model based on the full-cell equivalent impedance model.

[0046] The battery equivalent circuit model building device in this embodiment divides the frequency range into different frequency bands based on the impedance spectra of the positive and negative half-cells, and configures different equivalent impedance models for different frequency bands. This breaks the limitations of traditional fixed structure models. For the inductive effect in the high-frequency band, the charge transfer polarization in the mid-frequency band, and the ion diffusion process in the low-frequency band, the most suitable circuit structure is matched respectively. This avoids the problem of a single model ignoring inductance at high frequencies or insufficient fitting at low frequencies, significantly improving the fitting accuracy of the model across the entire frequency range. It achieves high-precision modeling over a wide frequency range, while taking into account both high-frequency dynamic response and low-frequency process accuracy, thereby improving the accuracy of battery state estimation over a wide operating frequency range.

[0047] This invention also provides a computer device, including: a memory, a processor, and a network interface connected via a system bus, wherein the memory stores at least one instruction, and the at least one instruction is loaded and executed by the processor to implement all or part of the steps of the aforementioned battery equivalent circuit model establishment method.

[0048] The network interface is used for network communication, such as sending assigned tasks. Those skilled in the art will understand that... Figure 9 The structure shown is merely a block diagram of a portion of the structure related to the present invention and does not constitute a limitation on the computer device to which the present invention is applied. A specific computer device may include more or fewer components than those shown in the figure, or combine certain components, or have different component arrangements.

[0049] A processor can be a CPU, or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components. A general-purpose processor can be a microprocessor, or any conventional processor. The processor is the control center of a computer device, connecting all parts of the computer device through various interfaces and lines.

[0050] Memory can be used to store computer programs and / or modules. The processor implements various functions of the computer device by running or executing the computer programs and / or modules stored in the memory, and by accessing data stored in the memory. Memory can mainly include a program storage area and a data storage area. The program storage area can store the operating system, application programs required for at least one function (such as video playback, image playback, etc.), etc.; the data storage area can store data created based on the use of the mobile phone (such as video data, image data, etc.). In addition, memory can include high-speed random access memory, and can also include non-volatile memory, such as hard disks, RAM, plug-in hard disks, SmartMedia Cards (SMC), Secure Digital Cards (SD cards), Flash Cards, at least one disk storage device, flash memory device, or other volatile solid-state storage devices.

[0051] In one embodiment, the processor is configured to run a computer program stored in memory to perform the following steps: Step S1: Obtain the impedance spectra of the positive half-cell and the negative half-cell obtained by electrochemical impedance spectroscopy testing in the three-electrode battery system. Step S2: Divide the frequency range into different frequency bands according to the impedance spectrum of the positive half-cell and the impedance spectrum of the negative half-cell, and configure different equivalent impedance models for different frequency bands. Step S3: Obtain the battery operating frequency, and select the equivalent impedance model of the positive half-cell and the equivalent impedance model of the negative half-cell according to the frequency band where the battery operating frequency is located. Step S4: Superimpose the selected positive half-cell equivalent impedance model and negative half-cell equivalent impedance model to obtain the full-cell equivalent impedance model, and then establish the battery equivalent circuit model based on the full-cell equivalent impedance model.

[0052] In an optional embodiment, the step of dividing the frequency range into multiple different frequency bands based on the impedance spectrum of the positive half-cell and configuring different equivalent impedance models for different frequency bands includes: Step S21: Determine the first frequency threshold, the second frequency threshold, and the third frequency threshold based on the impedance spectrum of the positive half-cell; wherein, the first frequency threshold > the second frequency threshold > the third frequency threshold; Step S22: Divide the frequency range into the following categories according to the first frequency threshold, the second frequency threshold, and the third frequency threshold: high frequency band above the first frequency threshold; mid-high frequency band between the first frequency threshold and the second frequency threshold; mid-low frequency band between the second frequency threshold and the third frequency threshold; and low frequency band below the third frequency threshold.

[0053] In an optional embodiment, the step of dividing the frequency range into multiple different frequency bands based on the impedance spectrum of the positive half-cell and configuring different equivalent impedance models for different frequency bands further includes: Step S23: Configure a first model containing inductive and ohmic resistor elements in the high-frequency band; Step S24: Configure a second model in the mid-to-high frequency band, which includes an inductor, an ohmic resistor, and at least one parallel RC unit. Step S25: Configure a third model in the low-to-medium frequency band, which includes an ohmic resistor element and at least one parallel RC unit. Step S26: Configure a fourth model in the low-frequency band, which includes an ohmic resistor element and at least two parallel RC units.

[0054] In an optional embodiment, determining the first frequency threshold, the second frequency threshold, and the third frequency threshold based on the impedance spectrum of the positive half-cell includes: The interpolation point between the two points where the sign of the imaginary part of the impedance spectrum of the positive half-cell is switched is used as the first frequency threshold. The frequency corresponding to the semicircular peak point in the impedance spectrum of the positive half-cell is used as the second frequency threshold. The frequency at which the relative error in the impedance spectrum of the positive half-cell exceeds a preset error threshold is taken as the third frequency threshold.

[0055] In an optional embodiment, the preset error threshold can be set to 3% to 5%.

[0056] In an optional embodiment, obtaining the impedance spectra of the positive half-cell and the negative half-cell obtained by electrochemical impedance spectroscopy testing in a three-electrode battery system further includes: Establish a fitted equivalent impedance model using inductor elements, ohmic resistor elements, and at least two parallel RC units; The impedance spectra of the positive and negative half-cells were fitted based on the fitted equivalent impedance model.

[0057] In an optional embodiment, after superimposing the selected positive half-cell equivalent impedance model and the negative half-cell equivalent impedance model to obtain the full-cell equivalent impedance model, the method further includes: Obtain the impedance spectrum of the full cell obtained by electrochemical impedance spectroscopy in a three-electrode battery system; The obtained full-cell impedance spectrum was used to verify the superimposed full-cell equivalent impedance model.

[0058] This invention also provides a computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements all or part of the steps of the aforementioned method for establishing a battery equivalent circuit model.

[0059] The embodiments of the present invention can implement all or part of the aforementioned processes, or they can be accomplished by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various methods described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include: any entity or device capable of carrying computer program code, recording media, USB flash drives, portable hard drives, magnetic disks, optical disks, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signals, telecommunication signals, and software distribution media, etc. It should be noted that the content included in the computer-readable medium can be appropriately added to or subtracted according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, computer-readable media do not include electrical carrier signals and telecommunication signals.

[0060] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, servers, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage and optical storage) containing computer-usable program code.

[0061] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or system that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or system. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or system that includes that element.

[0062] The serial numbers in the above embodiments of the present invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0063] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0064] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. 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 invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features of the invention herein.

Claims

1. A method for establishing a battery equivalent circuit model, characterized in that, Includes the following steps: Obtain the impedance spectra of the positive half-cell and the negative half-cell obtained by electrochemical impedance spectroscopy in a three-electrode battery system; Based on the impedance spectra of the positive and negative half-cell cells, the frequency range is divided into different frequency bands, and different equivalent impedance models are configured for different frequency bands. Obtain the battery operating frequency, and select the equivalent impedance model for the positive half-cell and the equivalent impedance model for the negative half-cell according to the frequency band in which the battery operating frequency is located. The equivalent impedance models of the selected positive half-cell and negative half-cell are superimposed to obtain the equivalent impedance model of the full cell. Then, the equivalent circuit model of the battery is established based on the equivalent impedance model of the full cell.

2. The method for establishing a battery equivalent circuit model according to claim 1, characterized in that, The process of dividing the frequency range into multiple different frequency bands based on the impedance spectrum of the positive half-cell and configuring different equivalent impedance models for different frequency bands includes: The first frequency threshold, the second frequency threshold, and the third frequency threshold are determined based on the impedance spectrum of the positive half-cell; wherein, the first frequency threshold > the second frequency threshold > the third frequency threshold; The frequency range is divided into the following categories based on the first frequency threshold, the second frequency threshold, and the third frequency threshold: high frequency band above the first frequency threshold; mid-to-high frequency band between the first and second frequency thresholds; mid-to-low frequency band between the second and third frequency thresholds; and low frequency band below the third frequency threshold.

3. The method for establishing a battery equivalent circuit model according to claim 2, characterized in that, The method of dividing the frequency range into multiple different frequency bands based on the impedance spectrum of the positive half-cell and configuring different equivalent impedance models for different frequency bands also includes: A first model containing inductive and ohmic resistor elements is configured in the high-frequency band. A second model is configured in the mid-to-high frequency band, comprising inductor elements, ohmic resistor elements, and at least one parallel RC unit. A third model is configured in the low-to-mid frequency band, which includes ohmic resistors and at least one parallel RC unit. A fourth model is configured in the low-frequency band, which includes ohmic resistor elements and at least two parallel RC units.

4. The method for establishing a battery equivalent circuit model according to claim 2, characterized in that, The determination of the first frequency threshold, the second frequency threshold, and the third frequency threshold based on the impedance spectrum of the positive half-cell includes: The interpolation point between the two points where the sign of the imaginary part of the impedance spectrum of the positive half-cell is switched is used as the first frequency threshold. The frequency corresponding to the semicircular peak point in the impedance spectrum of the positive half-cell is used as the second frequency threshold. The data in the impedance spectrum of the positive half-cell that are below the second frequency threshold are compared with the preset detection data, and the frequency corresponding to the relative error exceeding the preset error threshold is taken as the third frequency threshold.

5. The method for establishing a battery equivalent circuit model according to claim 4, characterized in that: The preset error threshold is set between 3% and 5%.

6. The method for establishing a battery equivalent circuit model according to claim 1, characterized in that, The method of obtaining the impedance spectra of the positive half-cell and the negative half-cell obtained by electrochemical impedance spectroscopy testing in a three-electrode battery system further includes: Establish a fitted equivalent impedance model using inductor elements, ohmic resistor elements, and at least two parallel RC units; The impedance spectra of the positive and negative half-cells were fitted based on the fitted equivalent impedance model.

7. The method for establishing a battery equivalent circuit model according to claim 3, characterized in that, After superimposing the selected positive half-cell equivalent impedance model and the negative half-cell equivalent impedance model to obtain the full-cell equivalent impedance model, the process further includes: Obtain the impedance spectrum of the full cell obtained by electrochemical impedance spectroscopy in a three-electrode battery system; The obtained full-cell impedance spectrum was used to verify the superimposed full-cell equivalent impedance model.

8. A device for establishing a battery equivalent circuit model, characterized in that, include: The acquisition unit is used to acquire the impedance spectra of the positive half-cell and the negative half-cell obtained by electrochemical impedance spectroscopy testing in a three-electrode battery system. The division unit is used to divide the frequency range into different frequency bands according to the impedance spectrum of the positive half-cell and the impedance spectrum of the negative half-cell, and to configure different equivalent impedance models for different frequency bands. Select a unit to obtain the battery operating frequency, and select the equivalent impedance model of the positive half-cell and the equivalent impedance model of the negative half-cell according to the frequency band where the battery operating frequency is located. A unit is established to superimpose the selected positive half-cell equivalent impedance model and the negative half-cell equivalent impedance model to obtain the full-cell equivalent impedance model, and then establish the battery equivalent circuit model based on the full-cell equivalent impedance model.

9. A computer device, characterized in that, include: A memory and a processor, wherein the memory stores at least one instruction, which is loaded and executed by the processor to implement the battery equivalent circuit model establishment method according to any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores computer instructions that, when executed by a computer, cause the computer to perform the battery equivalent circuit model establishment method according to any one of claims 1 to 7.

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