A method and apparatus for determining output voltage of a second-order equivalent circuit model

Abstract

The application provides a method and device for determining output voltage of a second-order equivalent circuit model. The method comprises: determining a target open-circuit voltage value of the second-order equivalent circuit model based on an initial open-circuit voltage value of the second-order equivalent circuit model corresponding to a target battery, an electrode reaction concentration ratio of the target battery, a temperature of the target battery at a current time, and a preset Nernst equation; determining a target ohmic internal resistance value of the second-order equivalent circuit model and a target ohmic voltage value corresponding to the target ohmic internal resistance value; and determining an output voltage of the second-order equivalent circuit model at the current time based on the target open-circuit voltage value, the target ohmic voltage value, a first voltage value of a first RC circuit in the second-order equivalent circuit model, and a second voltage value of a second RC circuit in the second-order equivalent circuit model. The application solves the problem of inaccurate model parameters of a traditional lithium-ion battery caused by temperature changes, thereby improving the accuracy of the model.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of new energy batteries, in particular to a method and device for determining output voltage of a second-order equivalent circuit model. BACKGROUND

[0002] With factors such as energy consumption and environmental pollution, developing new energy vehicles has become a general trend. In recent years, lithium ion batteries have gradually become the first choice of vehicle power sources due to their high energy conversion efficiency, high energy density, long cycle life and no memory effect. As a key component of the entire electric vehicle, the performance of the lithium ion battery plays a decisive role. Therefore, it is of great significance to establish an accurate battery model.

[0003] The reaction inside the lithium ion battery has the characteristics of high nonlinearity and time variation, and the internal parameters are affected by many factors, resulting in changes in the output voltage of the battery. The model accuracy of the traditional equivalent circuit model of the lithium ion battery is low. SUMMARY

[0004] Therefore, the purpose of the present application is to provide a method and device for determining the output voltage of a second-order equivalent circuit model, which solves the problem of inaccurate model parameters of traditional lithium ion batteries caused by temperature changes, and improves the accuracy of the model.

[0005] The application provides a method for determining the output voltage of a second-order equivalent circuit model, which comprises the following steps:

[0006] When the target battery to be detected is discharging, the initial open circuit voltage value of the second-order equivalent circuit model corresponding to the target battery, the electrode reaction concentration ratio of the target battery, the temperature of the target battery at the current time and the preset Nernst equation are used to determine the target open circuit voltage value of the second-order equivalent circuit model.

[0007] The initial ohmic resistance value of the second-order equivalent circuit model corresponding to the target battery, the preset Arrhenius equation and the preset three-parameter equation are used to determine the target ohmic resistance value of the second-order equivalent circuit model and the target ohmic voltage value corresponding to the target ohmic resistance value.

[0008] The target open circuit voltage value, the target ohmic voltage value, the first voltage value of the first RC circuit in the second-order equivalent circuit model and the second voltage value of the second RC circuit in the second-order equivalent circuit model are used to determine the output voltage of the second-order equivalent circuit model corresponding to the target battery at the current time.

[0009] Further, the formula for determining the target open circuit voltage value of the second-order equivalent circuit model is as follows:

[0010]

[0011] wherein Uocv is used to represent a target open circuit voltage value of the second-order equivalent circuit model, is used to represent an initial open circuit voltage value of the second-order equivalent circuit model, R is used to represent a molar gas constant, Z is used to represent a number of migrated electrons, T is used to represent an absolute temperature of the target battery at a current time, and F is used to represent a Faraday constant, is used to represent a concentration ratio of electrode reactions of the target battery.

[0012] Further, a formula for determining a target ohmic resistance value of the second-order equivalent circuit model is specifically as follows:

[0013]

[0014]

[0015] wherein |U1-U2| is used to represent a transient mutation terminal voltage difference occurring at a pulse just generation stage when the target battery is discharging, |U3-U4| is used to represent a transient mutation terminal voltage difference occurring after a pulse end when the target battery is discharging, I is used to represent a pulse current, A is used to represent a frequency factor, m is used to represent a constant term, E0 is used to represent an apparent activation energy constant, R is used to represent a molar gas constant, T is used to represent an absolute temperature of the target battery at a current time, R0 is used to represent an initial ohmic resistance value of the second-order equivalent circuit model, and y(RO) is used to represent a target ohmic resistance value of the second-order equivalent circuit model.

[0016] Further, a formula for determining a target ohmic voltage value corresponding to the target ohmic resistance value is as follows:

[0017] U R =y(RO)I;

[0018] wherein I is used to represent a pulse current, U R is used to represent a target ohmic voltage value, and y(RO) is used to represent a target ohmic resistance value of the second-order equivalent circuit model.

[0019] Further, the first voltage value and the second voltage value jointly constitute a polarization voltage value, and the polarization voltage value is determined by the following manner:

[0020] Based on a preset Butler-Volmer equation, a current density in the second-order equivalent circuit model, an exchange current density in the second-order equivalent circuit model, and a temperature of the target battery at a current time, an overpotential in the second-order equivalent circuit model is determined.

[0021] determine a polarization resistance in the first RC circuit and the second RC circuit according to the overpotential and the pulse current in the second-order equivalent circuit model;

[0022] determine a polarization voltage value according to the polarization resistance and the pulse current in a target battery.

[0023] The embodiment of the present application further provides a second-order equivalent circuit model output voltage determination device, which comprises:

[0024] A first determination module is configured to determine a target open circuit voltage value of a second-order equivalent circuit model corresponding to a target battery based on an initial open circuit voltage value of the second-order equivalent circuit model, an electrode reaction concentration ratio of the target battery, a temperature of the target battery at a current moment and a preset Nernst equation when the target battery is discharging.

[0025] A second determination module is configured to determine a target ohmic resistance value of the second-order equivalent circuit model and a target ohmic voltage value corresponding to the target ohmic resistance value based on an initial ohmic resistance value of the second-order equivalent circuit model, a preset Arrhenius equation and a preset three-parameter equation.

[0026] A third determination module is configured to determine an output voltage of the second-order equivalent circuit model corresponding to the target battery at the current moment based on the target open circuit voltage value, the target ohmic voltage value, a first voltage value of a first RC circuit in the second-order equivalent circuit model and a second voltage value of a second RC circuit in the second-order equivalent circuit model.

[0027] Further, the formula for determining the target open circuit voltage value of the second-order equivalent circuit model is specifically as follows:

[0028]

[0029] wherein Uocv is used for representing the target open circuit voltage value of the second-order equivalent circuit model, is used for representing the initial open circuit voltage value of the second-order equivalent circuit model, R is used for representing a molar gas constant, Z is used for representing a number of migration electrons, T is used for representing an absolute temperature of the target battery at the current moment, and F is used for representing a Faraday constant, is used for representing the electrode reaction concentration ratio of the target battery.

[0030] Further, the formula for determining the target ohmic resistance value of the second-order equivalent circuit model is specifically as follows:

[0031]

[0032]

[0033] wherein |U1-U2| is used to represent the instantaneous mutation terminal voltage difference of the target battery at the pulse just generation stage when discharging, |U3-U4| is used to represent the instantaneous mutation terminal voltage difference of the target battery after the pulse ends when discharging, I is used to represent the pulse current, A is used to represent the frequency factor, m is used to represent the constant term, E0 is used to represent the apparent activation energy constant, R is used to represent the molar gas constant, T is used to represent the absolute temperature of the target battery at the current moment, R0 is used to represent the initial ohmic internal resistance value of the second-order equivalent circuit model, and y(RO) is used to represent the target ohmic internal resistance value of the second-order equivalent circuit model.

[0034] The embodiment of the present application also provides an electronic device, comprising a processor, a memory and a bus, the memory stores machine readable instructions executable by the processor, the processor and the memory communicate through the bus when the electronic device is running, and the machine readable instructions are executed by the processor to perform the steps of the output voltage determination method of the second-order equivalent circuit model.

[0035] The embodiment of the present application also provides a computer readable storage medium, the computer readable storage medium stores a computer program, and the computer program is executed by the processor to perform the steps of the output voltage determination method of the second-order equivalent circuit model.

[0036] The output voltage determination method and device of the second-order equivalent circuit model provided by the embodiment of the present application, compared with the prior art, determines the target open circuit voltage value of the second-order equivalent circuit model through the initial open circuit voltage value of the second-order equivalent circuit model corresponding to the target battery, the electrode reaction concentration ratio of the target battery, the temperature of the target battery at the current moment and the preset Nernst equation, determines the target ohmic internal resistance value of the second-order equivalent circuit model and the target ohmic voltage value corresponding to the target ohmic internal resistance value based on the initial ohmic internal resistance value of the second-order equivalent circuit model corresponding to the target battery, the preset Arrhenius equation and the preset three-parameter equation, and then determines the output voltage of the second-order equivalent circuit model corresponding to the target battery at the current moment based on the target open circuit voltage value, the target ohmic voltage value, the first voltage value of the first RC circuit in the second-order equivalent circuit model and the second voltage value of the second RC circuit in the second-order equivalent circuit model, thereby solving the problem of inaccurate model parameters of the traditional lithium ion battery caused by temperature change, and further improving the accuracy of the model.

[0037] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the following preferred embodiments are described in detail below, and the accompanying drawings are described as follows. BRIEF DESCRIPTION OF DRAWINGS

[0038] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed to be used in the embodiments will be briefly introduced as follows. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor on the basis of the drawings.

[0039] Figure 1 A flow chart of a method for determining an output voltage of a second-order equivalent circuit model is shown;

[0040] Figure 2 A structural schematic diagram of a device for determining an output voltage of a second-order equivalent circuit model is shown;

[0041] Figure 3 A circuit structure diagram of a second-order equivalent circuit model in a method for determining an output voltage of a second-order equivalent circuit model is shown;

[0042] Figure 4 A structural schematic diagram of an electronic device is shown.

[0043] In the drawings:

[0044] 200 - output voltage determination device; 210 - first determination module; 220 - second determination module; 230 - third determination module; OCV - open circuit voltage source; R0 - ohmic internal resistance; R1 - first polarization resistance; R2 - second polarization resistance; C1 - first polarization capacitance; C2 - second polarization capacitance; 400 - electronic device; 410 - processor; 420 - memory; 430 - bus. DETAILED DESCRIPTION

[0045] In order to make the purposes, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. The components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. Based on the embodiments of the present application, every other embodiment obtained by those skilled in the art without creative labor falls within the scope of the present application.

[0046] Firstly, the application scenarios applicable to the present application are introduced. The present application can be applied to the field of new energy battery technology.

[0047] It is found through research that the reaction inside a lithium ion battery has the characteristics of high nonlinearity and time variation, the internal parameters thereof are affected by many factors to cause the change of the output voltage of the battery at the terminal, and the model precision of the traditional equivalent circuit model of the lithium ion battery is low.

[0048] The commonly used battery model of the traditional lithium ion battery is divided into three categories: an electrochemical model, a neural network model and an equivalent circuit model. The electrochemical model has high model precision and can describe the chemical reaction inside the battery, but it is difficult to identify all parameters. The neural network model has high classification accuracy for the battery and can fully clarify the complex nonlinear relationship, but a large number of parameters need to be obtained. The equivalent circuit model is simple in structure, and therefore, the embodiments of the present application research the equivalent circuit model of the lithium ion battery.

[0049] In the above, the temperature change of the battery is affected by the electric vehicle in different working environment temperatures and discharge states, and the traditional lithium ion battery cannot fully consider the influence of the temperature change on the internal parameters of the battery and the precision of the battery in the battery operation state.

[0050] Based on this, the embodiments of the present application provide a method and device for determining the output voltage of a second-order equivalent circuit model, solve the problem of inaccurate model parameters of the traditional lithium ion battery caused by temperature change, and further improve the precision of the model.

[0051] Please refer to Figure 1 , Figure 1 The flowchart of the method for determining the output voltage of the second-order equivalent circuit model provided by the embodiments of the present application is shown in Figure 1 The method for determining the output voltage of the second-order equivalent circuit model provided by the embodiments of the present application includes the following steps:

[0052] S101, when the target battery to be detected is discharged, determining the target open circuit voltage value of the second-order equivalent circuit model based on the initial open circuit voltage value of the second-order equivalent circuit model corresponding to the target battery, the electrode reaction concentration ratio of the target battery, the temperature of the target battery at the current moment and the preset Nernst equation.

[0053] In this step, when the target battery to be detected is discharged, the influence of the temperature change on the internal parameters of the target battery and the precision of the battery is fully considered, and the target open circuit voltage value of the second-order equivalent circuit model is determined based on the temperature of the target battery at the current moment and the initial open circuit voltage value of the second-order equivalent circuit model corresponding to the target battery and other parameter values.

[0054] Here, the embodiments provided in the present application use a second-order equivalent circuit model which has clear physical meaning and high model accuracy compared to other equivalent circuit models, and can more accurately and intuitively simulate the dynamic characteristics of the target battery.

[0055] In the embodiments provided in the present application, the second-order equivalent circuit model obtains an initial open circuit voltage value, an electrode reaction concentration ratio of the target battery, and a temperature of the target battery at the current time through a system on chip (SOC) of the target.

[0056] In this way, the embodiments provided in the present application use a hybrid pulse power characteristic (HPPC) to test the target battery to be detected, obtain the relationship between the initial open circuit voltage value and the pulse current of the test data, and the SOC difference of each group of current pulse test is 10%, to obtain the SOC-OCV relationship, a small rate constant current is used for discharging, and the target battery is discharged multiple times to a preset cut-off voltage, and the target battery needs to be rested for a period of time to restore to a relatively stable state before the target battery enters the next pulse.

[0057] In the above, the preset cut-off voltage in the embodiments provided in the present application can be customized according to different materials of the target battery, specifically:

[0058] If the target battery selects a lithium iron ion battery, the preset cut-off voltage is 2-3.65V.

[0059] If the target battery selects a ternary lithium ion battery, the preset cut-off voltage is 3-4.2V.

[0060] Optionally, the formula for determining the target open circuit voltage value of the second-order equivalent circuit model is specifically:

[0061]

[0062] In the formula, Uocv is used to represent the target open circuit voltage value of the second-order equivalent circuit model, is used to represent the initial open circuit voltage value of the second-order equivalent circuit model, R is used to represent the molar gas constant, Z is used to represent the number of migrated electrons, T is used to represent the absolute temperature of the target battery at the current time, and F is used to represent the Faraday constant, is used to represent the electrode reaction concentration ratio of the target battery.

[0063] In the above, in the state that the target battery is discharged at the current preset rate, the initial open circuit voltage value is obtained under the preset typical condition, the initial open circuit voltage value is irrelevant to the temperature, but is closely related to the SOC, and the initial open circuit voltage value is determined by the SOC of the target battery.

[0064] Here, the preset Nernst equation refers to an equation expression used to quantitatively describe a diffusion potential formed by a certain ion between A and B two systems.

[0065] In S102, the initial ohmic resistance value of the second-order equivalent circuit model corresponding to the target battery, the preset Arrhenius equation, and the preset three-parameter equation are used to determine the target ohmic resistance value of the second-order equivalent circuit model and the target ohmic voltage value corresponding to the target ohmic resistance value.

[0066] In this step, during the pulse process of discharging the target battery to be detected, the battery terminal voltage of the target battery to be detected will suddenly drop. The sudden voltage drop is considered as the voltage drop on the ohmic resistance. At the end of discharging, the voltage rising rate is extremely fast, which is similar to the sudden voltage drop during discharging. At this time, the process of the above voltage mutation is determined as the process of the disappearance of the ohmic resistance.

[0067] In the above, since the preset Arrhenius equation has a large response, and the Arrhenius equation does not have an absolute linear relationship when taking logarithm, it is necessary to introduce a preset three-parameter equation to determine the influence of the temperature at the current time on the ohmic resistance value, and the preset Arrhenius equation is suitable for a smaller temperature range, while the preset three-parameter equation is suitable for a wider temperature range.

[0068] The formula for determining the target ohmic resistance value of the second-order equivalent circuit model is as follows:

[0069]

[0070]

[0071] Where |U1-U2| is used to represent the instantaneous mutation terminal voltage difference of the target battery at the beginning of the pulse during discharging, |U3-U4| is used to represent the instantaneous mutation terminal voltage difference of the target battery after the end of the pulse during discharging, I is used to represent the pulse current, A is used to represent the frequency factor, m is used to represent the constant term, E0 is used to represent the apparent activation energy constant, R is used to represent the molar gas constant, T is used to represent the absolute temperature of the target battery at the current time, R0 is used to represent the initial ohmic resistance value of the second-order equivalent circuit model, and y(RO) is used to represent the target ohmic resistance value of the second-order equivalent circuit model.

[0072] In the above, in the state that the target battery is discharged using the current preset rate, the initial ohmic resistance value under the preset typical condition is obtained, and the initial ohmic resistance value is corrected by using the preset three-parameter equation.

[0073] Thus, the ohmic internal resistance mainly refers to the resistance composed of electrode materials, electrolyte, separator and contact resistance of each part, and is related to the size, structure, assembly and the like of the battery.

[0074] In the above, the logarithmic processing is performed on y(RO), and the specific formula is as follows:

[0075]

[0076] Optionally, the formula for determining the target ohmic voltage value corresponding to the target ohmic internal resistance value is as follows:

[0077] U R =y(RO)I;

[0078] Wherein, I is used to represent the pulse current, U R is used to represent the target ohmic voltage value, and y(RO) is used to represent the target ohmic internal resistance value of the second-order equivalent circuit model.

[0079] S103, based on the target open circuit voltage value, the target ohmic voltage value, the first voltage value of the first RC circuit in the second-order equivalent circuit model and the second voltage value of the second RC circuit in the second-order equivalent circuit model, determining the output voltage of the second-order equivalent circuit model corresponding to the target battery at the current time.

[0080] In this step, in the pulse discharge process of the target battery, the voltage decreases exponentially, and when the battery is in the resting process, there is no external input. The parameters of the first RC circuit and the second RC circuit are obtained in this stage, and the voltage response relationship is obtained by fitting method, which is as follows:

[0081] In the above, the formula of the first voltage value in the first RC circuit is specifically as follows:

[0082] Up1=U10e -t / τ1 =R1×I×e -t / τ1 ;

[0083] Thus, τ is used to represent the time constant, τ1=R1×C1, t is used to represent the time, and Up is used to represent the voltage change trend of the target battery polarization in the resting stage (current is 0), that is.

[0084] In the above, the formula of the second voltage value in the second RC circuit is specifically as follows:

[0085] Up2=U20e -t / τ1 =R2×I×e -t / τ1 ;

[0086] Thus, τ is used to represent the time constant, τ2 = R2 x C2, t is used to represent the time, and Up is used to represent the voltage change trend of the target battery polarization during the static stage (current is 0).

[0087] Up = U10e -t / τ1 + U20e -t / τ2 ;

[0088] Up is used to represent the voltage change trend of the battery polarization during the static stage (current is 0).

[0089] Optionally, the polarization voltage value composed of the first voltage value and the second voltage value is determined through the following sub-steps:

[0090] In sub-step 1031, the overpotential in the second-order equivalent circuit model is determined based on the preset Butler-Volmer equation, the current density in the second-order equivalent circuit model, the exchange current density in the second-order equivalent circuit model, and the temperature of the target battery at the current time.

[0091] In this step, the influence of absolute temperature and pulse current on polarization resistance and overpotential is determined according to the Butler-Volmer equation considering the diffusion process and the charge transfer process.

[0092] In the above, the preset Butler-Volmer equation is specifically:

[0093]

[0094] Wherein, J is used to represent the current density, j0 is used to represent the exchange current density, and respectively used to represent the supply of liquid phase mass transfer through the O end and the R end of the electrode, ΔΦ is used to represent the overpotential, and β is used to represent the constant term.

[0095] In the above, the formula of j0 is specifically:

[0096]

[0097] Wherein, ΔΦ = Φ - Φ e , Φ e is used to represent the equilibrium potential, Φ' is used to represent the reference potential, and Φ is used to represent the polarization potential of the electrode at the current time.

[0098] In the above, exp is used to represent the exponential function with the natural constant e as the base.

[0099] Here, That is, Φ e is greatly affected by temperature.

[0100] Sub-step 1032, determining the polarization resistance in the first RC circuit and the second RC circuit according to the overpotential and the pulse current in the second-order equivalent circuit model.

[0101] In the above description, whether the polarization resistance in the first RC circuit or the polarization resistance in the second RC circuit, is used to represent the polarization resistance value when the electrode potential deviates from its equilibrium value when (net) current flows on the electrode, and can be divided into anodic polarization and cathodic polarization according to the direction of the pulse current.

[0102] The formula of anodic polarization is specifically:

[0103]

[0104] Wherein, ΔΦ a is used to represent the anodic polarization overpotential.

[0105] The formula of cathodic polarization is specifically:

[0106]

[0107] Wherein, ΔΦ c is used to represent the cathodic polarization overpotential, and the first term in the above description is the electrochemical polarization term, and the last term is the concentration polarization term.

[0108] In the above description, when Φ e changes, the pulse increases rapidly, the exponential term accounts for a large proportion, and the liquid phase mass transfer term accounts for a small proportion, at this time, electrochemical polarization mainly occurs; under the condition of large ΔΦ difference, the pulse tends to a stable value, at this time, due to the large ratio of surface concentration to bulk concentration, the current is determined by the process of liquid phase mass transfer, at this time, concentration polarization mainly occurs.

[0109] Sub-step 1033, determining the polarization voltage value according to the polarization resistance and the pulse current in the target battery.

[0110] In the above description, the output voltage of the second-order equivalent circuit model corresponding to the target battery under the discharge state is specifically:

[0111]

[0112] Wherein, U is used to represent the output voltage of the second-order equivalent circuit model corresponding to the target battery at the current moment.

[0113] The method for determining the output voltage of the second-order equivalent circuit model provided in the embodiments of the present application, compared with the prior art, determines the target open circuit voltage value of the second-order equivalent circuit model by the initial open circuit voltage value of the second-order equivalent circuit model corresponding to the target battery, the electrode reaction concentration ratio of the target battery, the temperature of the target battery at the current moment, and the preset Nernst equation, determines the target ohmic internal resistance value of the second-order equivalent circuit model and the target ohmic voltage value corresponding to the target ohmic internal resistance value based on the initial ohmic internal resistance value of the second-order equivalent circuit model corresponding to the target battery, the preset Arrhenius equation, and the preset three-parameter equation, and then determines the output voltage of the second-order equivalent circuit model corresponding to the target battery at the current moment based on the target open circuit voltage value, the target ohmic voltage value, the first voltage value of the first RC circuit in the second-order equivalent circuit model, and the second voltage value of the second RC circuit in the second-order equivalent circuit model, thereby solving the problem of inaccurate model parameters of the traditional lithium ion battery caused by temperature change, and further improving the accuracy of the model.

[0114] Please refer to Figure 2 , Figure 2 The structure diagram of the output voltage determination device of the second-order equivalent circuit model provided in an embodiment of the present application is shown in FIG. 2. Figure 2 As shown in FIG. 2, the output voltage determination device 200 of the second-order equivalent circuit model provided in the embodiments of the present application comprises:

[0115] The first determination module 210 is configured to, when the target battery to be detected is discharging, determine the target open circuit voltage value of the second-order equivalent circuit model based on the initial open circuit voltage value of the second-order equivalent circuit model corresponding to the target battery, the electrode reaction concentration ratio of the target battery, the temperature of the target battery at the current moment, and the preset Nernst equation.

[0116] Optionally, the formula for determining the target open circuit voltage value of the second-order equivalent circuit model in the first determination module 210 is specifically as follows:

[0117]

[0118] wherein Uocv is used to represent the target open circuit voltage value of the second-order equivalent circuit model, is used to represent the initial open circuit voltage value of the second-order equivalent circuit model, R is used to represent the molar gas constant, Z is used to represent the number of transferred electrons, T is used to represent the absolute temperature of the target battery at the current moment, and F is used to represent the Faraday constant, is used to represent the electrode reaction concentration ratio of the target battery.

[0119] The second determining module 220 is configured to determine a target ohmic resistance value of the second-order equivalent circuit model and a target ohmic voltage value corresponding to the target ohmic resistance value based on an initial ohmic resistance value of the second-order equivalent circuit model corresponding to the target battery, a preset Arrhenius equation and a preset three-parameter equation.

[0120] Optionally, a formula for determining the target ohmic resistance value of the second-order equivalent circuit model in the second determining module 220 is as follows:

[0121]

[0122]

[0123] wherein |U1-U2| represents a transient sudden terminal voltage difference of the target battery at a pulse just generation stage during discharging, |U3-U4| represents a transient sudden terminal voltage difference of the target battery after a pulse end during discharging, I represents a pulse current, A represents a frequency factor, m represents a constant term, E0 represents an apparent activation energy constant, R represents a molar gas constant, T represents an absolute temperature of the target battery at a current moment, R0 represents the initial ohmic resistance value of the second-order equivalent circuit model, and y(RO) represents the target ohmic resistance value of the second-order equivalent circuit model.

[0124] Optionally, a formula for determining the target ohmic voltage value corresponding to the target ohmic resistance value in the second determining module 220 is as follows:

[0125] U R =y(RO)I;

[0126] wherein I represents the pulse current, U R represents the target ohmic voltage value, and y(RO) represents the target ohmic resistance value of the second-order equivalent circuit model.

[0127] The third determining module 230 is configured to determine an output voltage of the second-order equivalent circuit model corresponding to the target battery at a current moment based on the target open circuit voltage value, the target ohmic voltage value, a first voltage value of a first RC circuit in the second-order equivalent circuit model and a second voltage value of a second RC circuit in the second-order equivalent circuit model.

[0128] Optionally, the first voltage value and the second voltage value jointly constitute a polarization voltage value, and the polarization voltage value is determined in the following manner:

[0129] The overpotential in the second-order equivalent circuit model is determined based on a preset Butler-Volmer equation, a current density in the second-order equivalent circuit model, an exchange current density in the second-order equivalent circuit model and a temperature of the target battery at a current moment.

[0130] determine a polarization resistance in the first RC circuit and the second RC circuit according to the overpotential and the pulse current in the second-order equivalent circuit model.

[0131] determine a polarization voltage value according to the polarization resistance and the pulse current in the target battery.

[0132] The output voltage determination device 200 provided by the embodiments of the present application, compared with the prior art, determines a target open circuit voltage value of a second-order equivalent circuit model through an initial open circuit voltage value of the second-order equivalent circuit model corresponding to a target battery, an electrode reaction concentration ratio of the target battery, a temperature of the target battery at a current moment, and a preset Nernst equation, determines a target ohmic resistance value of the second-order equivalent circuit model and a target ohmic voltage value corresponding to the target ohmic resistance value based on an initial ohmic resistance value of the second-order equivalent circuit model corresponding to the target battery, a preset Arrhenius equation, and a preset three-parameter equation, and then determines an output voltage of the second-order equivalent circuit model corresponding to the target battery at the current moment based on the target open circuit voltage value, the target ohmic voltage value, a first voltage value of a first RC circuit in the second-order equivalent circuit model, and a second voltage value of a second RC circuit in the second-order equivalent circuit model, thereby solving the problem of inaccurate model parameters of a traditional lithium ion battery caused by temperature change, and further improving the accuracy of the model.

[0133] The embodiments provided by the present application solve the problem of inaccurate model parameters of a traditional lithium ion battery caused by temperature change by studying the influence of temperature on an open circuit voltage source, an ohmic resistance, and a polarization resistance through a preset Arrhenius equation, a preset Nernst equation, and a preset Butler-Volmer equation, thereby further improving the accuracy of the model.

[0134] Please refer to Figure 3 , Figure 3 The circuit structure diagram of the second-order equivalent circuit model in the output voltage determination method of the second-order equivalent circuit model provided by the embodiments of the present application is as follows. Figure 3As shown in the figure, the second-order equivalent circuit model includes an open circuit voltage source OCV, an ohmic internal resistance R0, a first polarization internal resistance R1, a first polarization capacitance C1, a second polarization internal resistance R2 and a second polarization capacitance C2, a positive terminal of the open circuit voltage source OCV is electrically connected with one end of the first polarization internal resistance R1 and one end of the first polarization capacitance C1 through one ohmic internal resistance R0, the other end of the first polarization internal resistance R1 is electrically connected with one end of the second polarization internal resistance R2, the other end of the first polarization capacitance C1 is electrically connected with one end of the second polarization capacitance C2, and the first polarization capacitance C1 and the first polarization internal resistance R1 are in parallel, the second polarization capacitance C2 and the second polarization internal resistance R2 are electrically connected, and the other end of the second polarization internal resistance R2 and the other end of the second polarization capacitance C2 are electrically connected with a negative terminal of the open circuit voltage source OCV.

[0135] Please refer to Figure 4 , Figure 4 A structural schematic diagram of an electronic device provided by an embodiment of the present application is shown in FIG. 4. Figure 4 As shown in the figure, the electronic device 400 includes a processor 410, a memory 420 and a bus 430.

[0136] The memory 420 stores machine readable instructions executable by the processor 410, when the electronic device 400 is running, the processor 410 and the memory 420 communicate through the bus 430, and the machine readable instructions executed by the processor 410 can execute the steps of the output voltage determination method of the second-order equivalent circuit model in the method embodiments shown in the above Figure 1 and Figure 2 The specific implementation can refer to the method embodiments, which will not be described here.

[0137] The embodiment of the present application also provides a computer readable storage medium, the computer readable storage medium stores a computer program, and the computer program can execute the steps of the output voltage determination method of the second-order equivalent circuit model in the method embodiments shown in the above Figure 1 and Figure 2 The specific implementation can refer to the method embodiments, which will not be described here.

[0138] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working process of the above-described system, device and unit can refer to the corresponding process in the foregoing method embodiments, which will not be described here.

[0139] In several embodiments provided in the present application, it should be understood that the disclosed system, device and method can be implemented in other manners. The described device embodiments are merely schematic, for example, the division of the units is only a logical function division, and there can be another division manner in actual implementation, for example, a plurality of units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the displayed or discussed mutual couplings or direct couplings or communication connections between different units, or the among different units, can be indirect couplings or communication connections through some interfaces, devices or units, and can be in electrical, mechanical or other forms.

[0140] The units described as separated components can or can not be physically separated, and the components displayed as units can or can not be physical units, i.e., can be located in one place, or can be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purposes of the embodiments of the present application.

[0141] In addition, each functional unit in the embodiments of the present application can be integrated in one processing unit, or each unit can exist physically as a separate unit, or two or more units can be integrated in one unit.

[0142] If the functions are implemented in the form of software function units and sold or used as independent products, they can be stored in a non-volatile computer readable storage medium executable by a processor. Based on this understanding, the technical solutions of the present application or the part of the technical solutions that make essential contributions to the prior art can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a plurality of instructions to make a computer device (which can be a personal computer, a server, or a network device, etc.) execute all or part of the steps of the methods described in the embodiments of the present application. The foregoing storage medium includes: a U disk, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk, and various media that can store program codes.

[0143] Finally, it should be noted that the above-described embodiments are merely specific embodiments of the present application, which are used to illustrate the technical solutions of the present application, but not to limit the same. The protection scope of the present application is not limited thereto. Although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that any skilled person in the art can still modify or easily think of changes to the technical solutions recorded in the foregoing embodiments, or make equivalent replacements to some of the technical features, within the technical scope disclosed by the present application. The modifications, changes or replacements do not make the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A method for determining the output voltage of a second-order equivalent circuit model, characterized in that, The method for determining the output voltage of the second-order equivalent circuit model includes: When the target battery to be tested is discharging, the target open-circuit voltage value of the second-order equivalent circuit model is determined based on the initial open-circuit voltage value of the target battery corresponding to the target battery, the electrode reaction concentration ratio of the target battery, the temperature of the target battery at the current moment, and the preset Nernst equation. Based on the initial ohmic internal resistance value, the preset Arrhenius equation, and the preset three-parameter equation of the second-order equivalent circuit model corresponding to the target battery, the target ohmic internal resistance value of the second-order equivalent circuit model and the target ohmic voltage value corresponding to the target ohmic internal resistance value are determined. Based on the target open-circuit voltage, the target ohmic voltage, the first voltage value of the first RC circuit in the second-order equivalent circuit model, and the second voltage value of the second RC circuit in the second-order equivalent circuit model, the output voltage of the second-order equivalent circuit model corresponding to the target battery at the current moment is determined.

2. The method for determining the output voltage of the second-order equivalent circuit model according to claim 1, characterized in that, The specific formula for determining the target open-circuit voltage value of the second-order equivalent circuit model is as follows: Uocv is used to characterize the target open-circuit voltage value of the second-order equivalent circuit model. The initial open-circuit voltage value is used to characterize the second-order equivalent circuit model; R is used to characterize the molar gas constant; Z is used to characterize the number of migrated electrons; T is used to characterize the absolute temperature of the target cell at the current moment; and F is used to characterize the Faraday constant. The electrode reaction concentration ratio used to characterize the target battery.

3. The method for determining the output voltage of the second-order equivalent circuit model according to claim 1, characterized in that, The formula for determining the target ohmic internal resistance value of the second-order equivalent circuit model is as follows: Wherein, |U1-U2| is used to characterize the instantaneous voltage difference at the beginning of the pulse generation stage when the target battery is discharging, |U3-U4| is used to characterize the instantaneous voltage difference at the end of the pulse when the target battery is discharging, I is used to characterize the pulse current, A is used to characterize the frequency factor, m is used to characterize the constant term, E0 is used to characterize the apparent activation energy constant, R is used to characterize the molar gas constant, T is used to characterize the absolute temperature of the target battery at the current moment, R0 is used to characterize the initial ohmic internal resistance value of the second-order equivalent circuit model, and y(RO) is used to characterize the target ohmic internal resistance value of the second-order equivalent circuit model.

4. The method for determining the output voltage of the second-order equivalent circuit model according to claim 3, characterized in that, The formula for determining the target ohmic voltage value corresponding to the target ohmic internal resistance value is: U R =y(RO)I; Where I is used to characterize the pulse current, U R Used to characterize the target ohmic voltage value, y(RO) is used to characterize the target ohmic internal resistance value of the second-order equivalent circuit model.

5. The method for determining the output voltage of the second-order equivalent circuit model according to claim 1, characterized in that, The first voltage value and the second voltage value together constitute the polarization voltage value, which is determined in the following manner: Based on the preset Butler-Folmer equation, the current density in the second-order equivalent circuit model, the exchange current density in the second-order equivalent circuit model, and the temperature of the target battery at the current moment, the overpotential in the second-order equivalent circuit model is determined. Based on the overpotential and the pulse current in the second-order equivalent circuit model, determine the polarization resistance in the first RC circuit and the second RC circuit; The polarization voltage value is determined based on the polarization internal resistance and the pulse current in the target battery.

6. A device for determining the output voltage of a second-order equivalent circuit model, characterized in that, The output voltage determination device for the second-order equivalent circuit model includes: The first determining module is used to determine the target open-circuit voltage value of the second-order equivalent circuit model based on the initial open-circuit voltage value of the second-order equivalent circuit model corresponding to the target battery, the electrode reaction concentration ratio of the target battery, the temperature of the target battery at the current moment, and the preset Nernst equation when the target battery to be detected is discharging. The second determining module is used to determine the target ohmic internal resistance value of the second-order equivalent circuit model and the target ohmic voltage value corresponding to the target ohmic internal resistance value based on the initial ohmic internal resistance value, the preset Arrhenius equation, and the preset three-parameter equation of the second-order equivalent circuit model corresponding to the target battery. The third determining module is used to determine the output voltage of the second-order equivalent circuit model corresponding to the target battery at the current moment based on the target open-circuit voltage value, the target ohmic voltage value, the first voltage value of the first RC circuit in the second-order equivalent circuit model, and the second voltage value of the second RC circuit in the second-order equivalent circuit model.

7. The output voltage determination device for the second-order equivalent circuit model according to claim 6, characterized in that, The specific formula for determining the target open-circuit voltage value of the second-order equivalent circuit model is as follows: Uocv is used to characterize the target open-circuit voltage value of the second-order equivalent circuit model. The initial open-circuit voltage value is used to characterize the second-order equivalent circuit model; R is used to characterize the molar gas constant; Z is used to characterize the number of migrated electrons; T is used to characterize the absolute temperature of the target cell at the current moment; and F is used to characterize the Faraday constant. The electrode reaction concentration ratio used to characterize the target battery.

8. The output voltage determination device for the second-order equivalent circuit model according to claim 6, characterized in that, The formula for determining the target ohmic internal resistance value of the second-order equivalent circuit model is as follows: Wherein, |U1-U2| is used to characterize the instantaneous voltage difference at the beginning of the pulse generation stage when the target battery is discharging, |U3-U4| is used to characterize the instantaneous voltage difference at the end of the pulse when the target battery is discharging, I is used to characterize the pulse current, A is used to characterize the frequency factor, m is used to characterize the constant term, E0 is used to characterize the apparent activation energy constant, R is used to characterize the molar gas constant, T is used to characterize the absolute temperature of the target battery at the current moment, R0 is used to characterize the initial ohmic internal resistance value of the second-order equivalent circuit model, and y(RO) is used to characterize the target ohmic internal resistance value of the second-order equivalent circuit model.

9. An electronic device, characterized in that, include: The device includes a processor, a memory, and a bus. The memory stores machine-readable instructions executable by the processor. When the electronic device is running, the processor communicates with the memory via the bus. The machine-readable instructions are executed by the processor to perform the steps of the output voltage determination method for a second-order equivalent circuit model as described in any one of claims 1 to 5.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed by a processor, performs the steps of the method for determining the output voltage of a second-order equivalent circuit model as described in any one of claims 1 to 5.

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