Battery equivalent circuit model, battery state estimation method and device

Abstract

The present application relates to a battery equivalent circuit model, a battery state assessment method, an apparatus, a computer device, a computer-readable storage medium, and a computer program product. The battery equivalent circuit model includes a resistance-capacitance module and an open-circuit voltage module. The open-circuit voltage module is connected to the resistance-capacitance module. The model parameters of the resistance-capacitance module and / or the open-circuit voltage module are parameter submodels related to the parameters of the battery's charge and discharge current. By associating the model parameters of the resistance-capacitance module and / or the open-circuit voltage module with the parameters of the battery's charge and discharge current, the established equivalent circuit model can more accurately describe battery characteristics than a traditional equivalent circuit model, thereby improving the voltage prediction accuracy of the equivalent circuit model under actual operating conditions.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a battery equivalent circuit model, a battery state estimation method, an apparatus, a computer device, a computer-readable storage medium, and a computer program product. Background Art

[0002] As a power battery model, the Equivalent Circuit Model (ECM) consists of an OCV (Open Circuit Voltage) and several resistors and capacitors. It describes the characteristics of power batteries to a certain extent and has strong engineering application value in on-board battery management systems, including battery state estimation. The accuracy of the ECM's voltage prediction under actual operating conditions has a crucial impact on the accuracy of state estimation. Improving the ECM's voltage prediction accuracy under actual operating conditions is an urgent issue. Summary of the Invention

[0003] Based on this, a battery equivalent circuit model, a battery state assessment method, an apparatus, a computer device, a computer-readable storage medium, and a computer program product are provided, which can improve the voltage prediction accuracy of the equivalent circuit model.

[0004] In a first aspect, the present application provides a battery equivalent circuit model, comprising a resistor-capacitor module and an open-circuit voltage module, wherein the open-circuit voltage module is connected to the resistor-capacitor module, and the model parameters of the resistor-capacitor module and / or the open-circuit voltage module are parameter submodels related to the parameters of the battery's charge and discharge current.

[0005] The battery equivalent circuit model includes a resistor-capacitor module and an open-circuit voltage module. The open-circuit voltage module is connected to the resistor-capacitor module. The model parameters of the resistor-capacitor module and / or the open-circuit voltage module are parameter submodels related to the parameters of the battery's charge and discharge current. By associating the model parameters of the resistor-capacitor module and / or the open-circuit voltage module with the parameters of the battery's charge and discharge current, the established equivalent circuit model can more accurately describe battery characteristics than traditional equivalent circuit models, thereby improving the voltage prediction accuracy of the equivalent circuit model under actual operating conditions.

[0006] In one embodiment, the battery's charge and discharge current parameters include battery temperature, electrode area, number of exchange electrons, maximum electrode ion concentration, electrode particle surface ion concentration, and electrolyte ion concentration at the reaction interface. Incorporating battery temperature, electrode area, number of exchange electrons, maximum electrode ion concentration, electrode particle surface ion concentration, and electrolyte ion concentration at the reaction interface as charge and discharge current parameters can improve the accuracy of model parameters.

[0007] In one embodiment, the model parameters include the polarization internal resistance of the RC module. The polarization internal resistance of the RC module is constructed based on the parameters of the battery's charge and discharge current, thereby improving the accuracy of the description of the polarization internal resistance of the RC module.

[0008] In one embodiment, the polarization internal resistance is a high-frequency polarization internal resistance, and a parametric submodel of the high-frequency polarization internal resistance is determined based on the relationship between the charge-discharge current and the reaction overpotential, as well as the relationship between the charge-transfer impedance and the reaction overpotential. Constructing a parametric submodel of the high-frequency polarization internal resistance based on the relationship between the charge-discharge current and the reaction overpotential, and the relationship between the charge-transfer impedance and the reaction overpotential, adds a description of the correlation between the charge-transfer impedance and the charge-discharge current, thereby improving the accuracy of the description of the high-frequency polarization internal resistance.

[0009] In one embodiment, the parametric submodel of the high-frequency polarization internal resistance is:

[0010]

[0011] in, I0=2Ai0, i0 represents the exchange current density, A is the electrode area, F and R are the Faraday constant and the ideal gas constant respectively, T is the battery temperature, n is the number of exchange electrons, R1 is the high-frequency polarization internal resistance, and I is the charge and discharge current.

[0012] In one embodiment, the model parameters include the state of charge in the open circuit voltage module. The state of charge in the open circuit voltage module is constructed according to the parameters of the battery's charge and discharge current, thereby improving the accuracy of the description of the state of charge in the open circuit voltage module.

[0013] In one embodiment, the parameters of the battery's charge and discharge current also include the electrode solid-phase particle size, electrode thickness, solid-phase porosity, and solid-phase diffusion coefficient; the state of charge is the sum of the electrode concentration difference state of charge and the electrode average state of charge, and the parametric submodel of the electrode concentration difference state of charge is determined based on an iterative expression for the electrode solid-phase particle ion concentration difference. Simultaneously, the parametric submodel of the electrode concentration difference state of charge is determined by combining the electrode solid-phase particle size, solid-phase diffusion coefficient, electrode thickness, solid-phase porosity, and an iterative expression for the electrode solid-phase particle ion concentration difference. The sum of the electrode concentration difference state of charge and the electrode average state of charge is used as the state of charge of the open-circuit voltage module, thereby adding a description of the electrode solid-phase concentration polarization and improving the accuracy of the state of charge description.

[0014] In one embodiment, the parametric submodel of the electrode concentration difference charge state is:

[0015]

[0016] Among them, τ diffis the diffusion time constant, T S is the calculation period, A is the electrode area, L is the electrode thickness, α is the constant coefficient, ε S is the solid phase porosity, F is the Faraday constant, C s,max is the maximum ion concentration of the electrode; SOCd elta (t k ) represents t k Electrode concentration difference state of charge at the moment, SOC delta (t k-1 ) represents t k-1 The electrode concentration difference charge state at the moment, I(t k ) represents t k The charge and discharge current at each moment.

[0017] In a second aspect, the present application provides a battery state estimation method, comprising: performing battery state estimation according to the above-mentioned battery equivalent circuit model.

[0018] In a third aspect, the present application provides a battery state estimation device, including a state estimation module, for performing battery state estimation based on the above-mentioned equivalent circuit model.

[0019] In a fourth aspect, the present application provides a computer device comprising a memory and a processor, wherein the memory stores a computer program, and the processor implements the steps of the above method when executing the computer program.

[0020] In a fifth aspect, the present application provides a computer-readable storage medium having a computer program stored thereon, which implements the steps of the above method when executed by a processor.

[0021] In a sixth aspect, the present application provides a computer program product, comprising a computer program, which implements the steps of the above method when executed by a processor. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0023] Figure 1 is a structural block diagram of a battery equivalent circuit model in one embodiment;

[0024] Figure 2 is a structural block diagram of a battery equivalent circuit model in another embodiment;

[0025] Figure 3 This is the structural principle diagram of the current battery equivalent circuit model;

[0026] Figure 4 This is the structural principle diagram of the battery equivalent circuit model of this application;

[0027] Figure 5 1 is a diagram of the internal structure of a computer device in one embodiment. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solutions and advantages of this application more clear, the following further describes this application in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art 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" and any variations thereof in the specification and claims of this application and the above-mentioned figure descriptions are intended to cover non-exclusive inclusions.

[0030] In the description of the embodiments of this application, the technical terms "first" and "second" are used only to distinguish different objects and should not be understood to indicate or imply relative importance or implicitly specify the quantity, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, the meaning of "plurality" is more than two, unless otherwise clearly and specifically defined.

[0031] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0032] In the description of the embodiments of this application, the term "and / or" is simply a description of the association relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent the following three situations: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.

[0033] 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).

[0034] In the description of the embodiments of the present application, the technical terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the embodiments of the present application.

[0035] In the description of the embodiments of the present application, unless otherwise expressly specified or limited, technical terms such as "installed," "connected," "connected," and "fixed" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integration; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; internal connections between two components or interactions between two components. Those skilled in the art can understand the specific meanings of the above terms in the embodiments of the present application based on specific circumstances.

[0036] With the development of science and technology and the continuous progress of society, the application field of power batteries has been continuously expanded. They are not only used in electric vehicles such as electric bicycles, electric motorcycles, and electric vehicles, but also in multiple fields such as military equipment and aerospace. The power battery is the power source that provides the power source for the tool. Most of them use valve-sealed lead-acid batteries, open-type tubular lead-acid batteries, and lithium iron phosphate batteries. They have the characteristics of high energy, high power, and high energy density. As a classic modeling method for power batteries, the equivalent circuit model has a decisive influence on the accuracy of the state estimation algorithm in terms of the voltage prediction accuracy under actual working conditions. Based on this, the present application provides an equivalent circuit model, including a resistance-capacitance module and an open-circuit voltage module. The model parameters of the resistance-capacitance module and / or the open-circuit voltage module are parameter submodels related to the parameters of the battery's charge and discharge current. By associating the model parameters of the resistance-capacitance module and / or the open-circuit voltage module with the parameters of the battery's charge and discharge current, the established equivalent circuit model can more accurately describe the battery characteristics than the traditional equivalent circuit model, thereby improving the voltage prediction accuracy of the equivalent circuit model under actual working conditions.

[0037] The battery equivalent circuit model provided in the embodiment of the present application can be constructed according to the parameters of the charge and discharge current of the battery to construct the model parameters to be optimized in the resistance-capacitance module and / or the open-circuit voltage module, and in combination with the relevant parameters of the battery, the other model parameters in the resistance-capacitance module and the open-circuit voltage module are constructed to obtain an optimized battery equivalent circuit model; or it can be constructed according to the parameters of the charge and discharge current of the battery to construct the model parameters to be optimized in the resistance-capacitance module and / or the open-circuit voltage module, and then the obtained model parameters are used to reconstruct the model parameters of the initial equivalent circuit model to obtain an optimized battery equivalent circuit model. It should be noted that the battery involved in the embodiment of the present application can be, but is not limited to, used in electrical devices such as vehicles, ships or aircraft.

[0038] In one embodiment, Figure 1 As shown, a battery equivalent circuit model is provided, including a resistor-capacitor module 110 and an open-circuit voltage module 120. The open-circuit voltage module 120 is connected to the resistor-capacitor module 110. The model parameters of the resistor-capacitor module 110 and / or the open-circuit voltage module 120 are parameter submodels related to the parameters of the battery's charge and discharge current.

[0039] Specifically, the model parameters are components of the RC module 110 and the open circuit voltage module 120, and the parameter submodel is used to characterize the corresponding relationship between the model parameters and the parameters of the battery's charge and discharge current. It can be understood that the model parameters in the RC module 110 and the open circuit voltage module 120 are not the same. For example, the model parameters of the RC module 110 may include polarization internal resistance, polarization capacitance, etc., and the model parameters of the open circuit voltage module 120 may include state of charge, etc. Taking the simultaneous optimization of the polarization internal resistance of the RC module 110 and the state of charge of the open circuit voltage module 120 as an example, the parameter submodels of the polarization internal resistance and state of charge can be constructed respectively according to the parameters of the battery's charge and discharge current, and then the optimized polarization internal resistance and state of charge are reconstructed with the polarization internal resistance and state of charge in the initial equivalent circuit model to obtain an optimized battery equivalent circuit model.

[0040] Furthermore, the RC module 110 may include an RC unit and an ohmic internal resistor, wherein the RC unit is composed of a polarized internal resistor and a polarized capacitor in parallel. Depending on the type of the battery equivalent circuit model, the specific structure of the RC module 110 may also be different. For example, the battery equivalent circuit model may be a second-order equivalent circuit model. Figure 2 As shown, the RC module 110 includes a first RC unit 112, a second RC unit 114, and an ohmic internal resistor R3 connected in sequence, and the ohmic internal resistor R3 is connected to the open circuit voltage module 120. The first RC unit 112 is obtained by connecting a high-frequency polarization internal resistor and a high-frequency polarization capacitor in parallel, and the second RC unit 114 is obtained by connecting a low-frequency polarization internal resistor and a low-frequency polarization capacitor in parallel.

[0041] The above-mentioned battery equivalent circuit model, by associating the model parameters of the resistance-capacitance module 110 and / or the open-circuit voltage module 120 with the parameters of the battery's charge and discharge current, enables the established equivalent circuit model to more accurately describe the battery characteristics than the traditional equivalent circuit model, thereby improving the voltage prediction accuracy of the equivalent circuit model under actual working conditions.

[0042] The specific types of charge and discharge current parameters are not exclusive and may include battery temperature, electrode area, maximum electrode ion concentration, electrode particle surface ion concentration, and reaction interface electrolyte ion concentration. The ions may be lithium ions or other ions. For lithium-ion batteries, the maximum electrode ion concentration, electrode particle surface ion concentration, and reaction interface electrolyte ion concentration are the maximum electrode lithium ion concentration, the electrode particle surface lithium ion concentration, and the reaction interface electrolyte lithium ion concentration, respectively. In one embodiment, the battery charge and discharge current parameters include battery temperature, electrode area, number of exchange electrons, maximum electrode ion concentration, electrode particle surface ion concentration, and reaction interface electrolyte ion concentration. By referencing battery temperature, electrode area, number of exchange electrons, maximum electrode ion concentration, electrode particle surface ion concentration, and reaction interface electrolyte ion concentration, model parameters in the resistance-capacitance module 110 and / or open-circuit voltage module 120 are constructed to obtain a parametric submodel of the relevant model parameters. Simultaneously incorporating battery temperature, electrode area, number of exchange electrons, maximum electrode ion concentration, electrode particle surface ion concentration, and reaction interface electrolyte ion concentration as charge and discharge current parameters can improve the accuracy of the model parameters.

[0043] In one embodiment, the model parameters include the polarization internal resistance in the RC module 110. The polarization internal resistance in the RC module 110 is constructed according to the parameters of the charge and discharge current of the battery, thereby improving the description accuracy of the polarization internal resistance in the RC module 110. Specifically, the polarization internal resistance optimized in the equivalent circuit model can be the high-frequency polarization internal resistance in the first RC unit 112, or the low-frequency polarization internal resistance in the second RC unit 114. In one embodiment, the polarization internal resistance is a high-frequency polarization internal resistance, and the parametric submodel of the high-frequency polarization internal resistance is determined based on the relationship between the charge and discharge current and the reaction overpotential, and the relationship between the charge transfer impedance and the reaction overpotential. Based on the relationship between the charge and discharge current and the reaction overpotential, and the relationship between the charge transfer impedance and the reaction overpotential, a parametric submodel of the high-frequency polarization internal resistance is constructed, which increases the description of the correlation between the charge transfer impedance and the charge and discharge current, thereby improving the description accuracy of the high-frequency polarization internal resistance.

[0044] Specifically, in one embodiment, the parametric submodel of the high-frequency polarization internal resistance is:

[0045]

[0046] in, I0=2Ai0, i0 represents the exchange current density, A is the electrode area, F and R are the Faraday constant and the ideal gas constant respectively, T is the battery temperature, n is the number of exchange electrons, R1 is the high-frequency polarization internal resistance, and I is the charge and discharge current.

[0047] In one embodiment, the model parameters include the state of charge in the open circuit voltage module 120. The state of charge in the open circuit voltage module 120 is constructed based on the parameters of the battery's charge and discharge current, thereby improving the accuracy of the description of the state of charge in the open circuit voltage module 120. Furthermore, the parameters of the battery's charge and discharge current also include the electrode solid phase particle size, electrode thickness, solid phase porosity, and solid phase diffusion coefficient. The state of charge is the sum of the electrode concentration difference state of charge and the electrode average state of charge. The parametric submodel of the electrode concentration difference state of charge is determined based on an iterative expression for the electrode solid phase particle ion concentration difference. In this embodiment, the parametric submodel of the electrode concentration difference state of charge is determined by combining the electrode solid phase particle size, solid phase diffusion coefficient, electrode thickness, solid phase porosity, and the iterative expression for the electrode solid phase particle ion concentration difference. The sum of the electrode concentration difference state of charge and the electrode average state of charge is used as the state of charge of the open circuit voltage module 120, thereby adding a description of the electrode solid phase concentration polarization and improving the accuracy of the description of the state of charge.

[0048] Specifically, in one embodiment, the parametric submodel of the electrode concentration difference state of charge is:

[0049]

[0050] Among them, τ diff is the diffusion time constant, T S To calculate the cycle, A is the electrode area (i.e., electrode coating area), L is the electrode thickness, α is a constant coefficient, ε S is the solid phase porosity, F is the Faraday constant, C s,max is the maximum ion concentration of the electrode; SOCd elta (t k ) represents t k Electrode concentration difference state of charge at the moment, SOC delta (t k-1 ) represents t k-1 The electrode concentration difference charge state at the moment, I(t k ) represents t k The charge and discharge current at each moment.

[0051] To better understand the above-mentioned battery equivalent circuit model, the optimization modeling process of the model is explained in detail below using the second-order equivalent circuit model of a lithium battery as an example.

[0052] ECM has strong engineering application value in vehicle-mounted battery management systems and can participate in the estimation algorithms of states such as SOC (State of Charge), SOH (State of Health), and SOP (State of Power) of the power battery system. The voltage prediction accuracy of ECM under actual working conditions has a decisive influence on the accuracy of battery state estimation. However, the current ECM has the following defects: 1) Lack of description of the correlation between charge transfer impedance and charge and discharge current; 2) Lack of description of electrode solid phase concentration polarization. Accordingly, in actual applications, the following failure scenarios exist, which restrict the application of ECM in some scenarios: 1) Failure of voltage prediction under low-temperature and high-rate pulse current conditions; 2) Failure of voltage prediction under low-temperature and high-rate continuous current conditions.

[0053] Based on this, this application makes a series of improvements to the structure and parameter identification methods of the traditional ECM, so that it has higher voltage prediction accuracy under 1) low-temperature and high-rate pulse current conditions; 2) low-temperature and high-rate continuous conditions, thereby improving the accuracy of the power battery management system state estimation algorithm.

[0054] Specifically, this application makes the following improvements to the structure and parameters of the ECM:

[0055] 1) According to the electrode reaction equation, the polarization internal resistance R in the RC (Resistance-Capacity) link is reconstructed as a function F1 of the charge and discharge current I. The parameters of F1 include R0 and k.

[0056] 2) Reconstruct the SOC in the OCV (SOC) link into the average state of charge SOC of the electrode avg and electrode concentration difference state of charge SOC delta The sum of which SOC avg Obtained by the ampere-hour integration method, SOC delta Simplified according to Fick's second law, the design is similar to the historical SOC delta , the function F2 related to the charge and discharge current I, the parameters of F2 include the diffusion time constant τ diff .

[0057] The improved ECM is obtained by combining the above processes.

[0058] Compared with the current ECM, the improved ECM has the following advantages: 1) low-temperature, high-rate pulse current conditions; 2) higher voltage prediction accuracy under low-temperature, high-rate continuous current conditions; accordingly, the state estimation algorithm based on the improved ECM is more accurate under the above two conditions than the state estimation algorithm based on the current ECM.

[0059] like Figure 3and (1), which are the topological structure and state space equation of the current second-order equivalent circuit model respectively.

[0060]

[0061] Among them, u1, u2 and SOC correspond to the high-frequency response polarization voltage, low-frequency response polarization voltage and state of charge of the model respectively; R1 and τ1 correspond to the high-frequency polarization internal resistance and high-frequency time constant respectively, R2 and τ2 correspond to the low-frequency polarization internal resistance and low-frequency time constant respectively, C1 and C2 correspond to the high-frequency polarization capacitance and low-frequency polarization capacitance respectively, the high-frequency time constant τ1 is the product of the high-frequency polarization internal resistance R1 and the high-frequency polarization capacitance C1, the low-frequency time constant τ2 is the product of the low-frequency polarization internal resistance R2 and the low-frequency polarization capacitance C2, and R3 is the ohmic internal resistance; CAP is the battery capacity, I is the charge and discharge current of the battery; OCV(SOC) is the open circuit voltage related to the state of charge; u L is the operating voltage of the battery.

[0062] The topology and state space equations of the improved second-order equivalent circuit model proposed in this application are as follows: Figure 4 and shown in formula (2).

[0063]

[0064]

[0065] u L =u1+u2+IR3+U eq (SOC avg +SOC delta ) (2)

[0066] The following is a detailed explanation of the model improvement ideas and derivation process.

[0067] 1) According to the electrode reaction equation (also known as the Butler-Volmer formula), the relationship between the reaction current (i.e., charge and discharge current) I and the reaction overpotential η can be expressed as:

[0068]

[0069]

[0070] Where i0 represents the exchange current density, A is the electrode area, F and R are the Faraday constant and the ideal gas constant respectively, T is the battery temperature, and n is the number of exchange electrons. For lithium-ion batteries, n = 1. ct is the electrode reaction rate constant, C s,max 、C s,surf and C eThey are the maximum lithium ion concentration of the electrode, the lithium ion concentration on the surface of the electrode particles, and the lithium ion concentration of the electrolyte at the reaction interface.

[0071] Let I0=2Ai0, Formula (3) can be transformed into:

[0072]

[0073] Further deformation yields:

[0074]

[0075] Then the electrode reaction impedance (i.e. charge transfer impedance) is:

[0076]

[0077] make If the high-frequency impedance in the equivalent circuit model is given the meaning of electrode reaction impedance, the high-frequency polarization internal resistance R1 can finally be expressed as a function F1 of the charge and discharge current I:

[0078]

[0079] Among them, R0 and k can be considered as parameters related to SOC and temperature.

[0080] 2) Electrode potential U eq The lithium ion concentration C on the surface of the electrode solid particles s,surf Directly related, due to the limitation of reaction kinetics, C s,surf The average lithium ion concentration C of solid particles s,avg There is a concentration difference C s,delta :

[0081] C s,surf =C s,avg +C s,delta (9)

[0082] The distribution of lithium ion concentration on the surface and inside the solid particles can be considered to follow Fick's second law. s,delta The solution is simplified to a first-order iterative link:

[0083]

[0084] Among them, C s,delta (t k ) represents t k The concentration difference at each moment, C s,delta (t k-1 ) represents t k-1 The concentration difference at the time, I(t k ) represents tk The charge and discharge current at the moment, T s is the calculation period (s), R s is the electrode solid phase particle size (m), A is the electrode area (m 2 ), L is the electrode thickness (m), which can be considered as the sum of the thickness of the positive and negative electrodes in this application, ε s is the solid phase porosity, which can be considered as the average value of the positive and negative solid phase porosities in this application, F is the Faraday constant, and D s is the solid phase diffusion coefficient (m 2 / s),D s and the diffusion time constant τ diff The relationship is:

[0085]

[0086] Where α is a constant coefficient. Integrating equations (10) and (11), we obtain:

[0087]

[0088] Divide both sides of the equation by the maximum lithium ion concentration C of the electrode s,max , the electrode concentration difference state of charge SOC can be obtained delta The iterative formula is:

[0089]

[0090] Among them, SOCd elta (t k ) represents t k Electrode concentration difference state of charge at the moment, SOC delta (t k-1 ) represents t k-1 The electrode concentration difference charge state at the moment, I(t k ) represents t k The charge and discharge current at the moment, the diffusion time constant τ diff is the parameter of function F2. Then we get:

[0091] SOC surf =SOC avg +SOC delta (14)

[0092] Among them, SOC avg is the average state of charge of the electrode, which can be obtained by the ampere-hour integration method; SOC surf It is the charge state of the solid surface of the electrode and is directly related to the electrode potential. eq It can be expressed as:

[0093] U eq =U eq(SOC avg +SOC delta )=U eq (SOC surf ) (15)

[0094] In one embodiment, a battery state estimation method is also provided, comprising: performing battery state estimation based on the above-mentioned battery equivalent circuit model. After determining the battery parameter values based on the actual battery structure, the battery parameter values are substituted into an equivalent circuit model corresponding to the battery. The equivalent circuit model and the actual collected charge and discharge currents are then combined to form an estimation algorithm for the power battery system's SOC, SOH, and SOP to estimate the battery state.

[0095] Based on the same inventive concept, embodiments of the present application also provide a battery state estimation device for implementing the aforementioned battery state estimation method. The solution provided by this device is similar to the solution described in the aforementioned method. Therefore, the specific limitations of one or more battery state estimation device embodiments provided below can be found in the aforementioned limitations of the battery state estimation method and will not be further elaborated here.

[0096] In one embodiment, a battery state estimation device is provided, including a state estimation module, configured to perform battery state estimation according to the above-mentioned equivalent circuit model.

[0097] In one embodiment, a computer device is provided. The computer device may be a terminal, and its internal structure diagram may be as follows: Figure 5 As shown. The computer device includes a processor, a memory, a communication interface, a display unit and an input device connected via a system bus. The processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The communication interface of the computer device is used to communicate with an external terminal in a wired or wireless manner, and the wireless manner can be achieved through WIFI, a mobile cellular network, NFC (near field communication) or other technologies. When the computer program is executed by the processor, a battery state estimation method is implemented. The display unit of the computer device can be a liquid crystal display or an electronic ink display, and the input device of the computer device can be a touch layer covering the display unit, or a button, trackball or touchpad provided on the computer device housing, or an external keyboard, touchpad or mouse.

[0098] Those skilled in the art will understand that Figure 5The structure shown in the figure is only a block diagram of a part of the structure related to the solution of the present application, and does not constitute a limitation on the computer device to which the solution of the present application is applied. The specific computer device may include more or fewer components than shown in the figure, or combine certain components, or have a different component arrangement.

[0099] In one embodiment, a computer device is provided, including a memory and a processor. The memory stores a computer program, and the processor implements the steps in the above method embodiments when executing the computer program.

[0100] In one embodiment, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, the steps in the above-mentioned method embodiments are implemented.

[0101] In one embodiment, a computer program product is provided, including a computer program, which implements the steps in the above method embodiments when executed by a processor.

[0102] Those skilled in the art will appreciate that all or part of the processes in the above-described method embodiments can be implemented by instructing the relevant hardware through a computer program. The computer program can be stored in a computer-readable storage medium. When executed, the program can include the processes in the above-described method embodiments. The aforementioned storage medium can be a non-volatile storage medium such as a magnetic disk, an optical disk, a read-only memory (ROM), or a random access memory (RAM).

[0103] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0104] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art could make various modifications and improvements without departing from the spirit of the present application, all of which fall within the scope of protection of the present application. Therefore, the scope of protection of the present patent application shall be determined by the appended claims.

Claims

1. A battery equivalent circuit model, characterized in that: The system comprises a resistance-capacitance module and an open-circuit voltage module, wherein the open-circuit voltage module is connected to the resistance-capacitance module, and the model parameters of the resistance-capacitance module and / or the open-circuit voltage module are parameter submodels related to the parameters of the charge and discharge current of the battery; Wherein, the model parameters include polarized internal resistance or polarized capacitance in the resistance and capacitance module; The model parameters include the state of charge in the open circuit voltage module.

2. The battery equivalent circuit model according to claim 1, characterized in that: The parameters of the charge and discharge current of the battery include battery temperature, electrode area, number of exchange electrons, maximum electrode ion concentration, electrode particle surface ion concentration and reaction interface electrolyte ion concentration.

3. The battery equivalent circuit model according to claim 1, characterized in that: The polarization internal resistance is a high-frequency polarization internal resistance, and a parametric sub-model of the high-frequency polarization internal resistance is determined based on the relationship between the charge-discharge current and the reaction overpotential, and the relationship between the charge transfer impedance and the reaction overpotential.

4. The battery equivalent circuit model according to claim 1, wherein: The parameters of the battery's charge and discharge current also include the electrode solid phase particle size, electrode thickness, solid phase porosity, and solid phase diffusion coefficient; the state of charge is the sum of the electrode concentration difference state of charge and the electrode average state of charge, and the parameter submodel of the electrode concentration difference state of charge is determined based on an iterative expression of the electrode solid phase particle ion concentration difference.

5. A battery state estimation method, characterized in that: include: Battery state estimation is performed according to the battery equivalent circuit model according to any one of claims 1 to 4.

6. A battery state estimation device, characterized in that: It includes a state estimation module, which is used to estimate the battery state according to the equivalent circuit model according to any one of claims 1 to 4.

7. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the method according to claim 5 are implemented.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to claim 5 are implemented.

9. A computer program product comprising a computer program, characterized in that When the computer program is executed by a processor, the steps of the method according to claim 5 are implemented.

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