CN116338471A - Output voltage determining method and device of second-order equivalent circuit model - Google Patents
Output voltage determining method and device of second-order equivalent circuit model Download PDFInfo
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Abstract
The application provides a method and a device for determining output voltage of a second-order equivalent circuit model, wherein the method for determining output voltage of the second-order equivalent circuit model comprises the following steps: 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 the 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 the output voltage of the second-order equivalent circuit model 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. The method solves the problem that the model parameters of the traditional lithium ion battery are inaccurate due to temperature change, and further improves the accuracy of the model.
Description
Technical Field
The application relates to the technical field of new energy batteries, in particular to a method and a device for determining output voltage of a second-order equivalent circuit model.
Background
Along with the factors such as energy consumption and environmental pollution, the development of new energy automobiles is becoming a trend, in recent years, lithium ion batteries gradually become the first choice of vehicle power sources due to the excellent characteristics of high energy conversion efficiency, high energy density, long cycle life, no memory effect and the like, and the lithium ion batteries serve as key components of the whole electric automobiles, the performance of the lithium ion batteries plays a decisive factor, so that the establishment of an accurate battery model has important significance.
The internal reaction of the lithium ion battery is characterized by high nonlinearity and time variation, the internal parameters of the lithium ion battery are influenced by a plurality of factors to cause the change of the output voltage of the battery terminal, and the model precision of the equivalent circuit model of the traditional lithium ion battery is lower.
Disclosure of Invention
In view of this, the present application aims to provide a method and a device for determining an output voltage of a second-order equivalent circuit model, which solve the problem of inaccurate model parameters of a traditional lithium ion battery caused by temperature change, thereby improving the accuracy of the model.
The embodiment of the application provides a method for determining the output voltage of a second-order equivalent circuit model, which comprises the following steps:
when a target battery to be detected discharges, determining a target open-circuit voltage value of a second-order equivalent circuit model based on an initial open-circuit voltage value of the second-order equivalent circuit model corresponding to the 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 based on an initial ohmic internal 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 determining 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.
Further, the formula for determining the target open circuit voltage value of the second-order equivalent circuit model is specifically as follows:
wherein Uocv is used for representing a target open circuit voltage value of the second-order equivalent circuit model,
the initial open circuit voltage value used for representing the second-order equivalent circuit model is R used for representing molar gas constant, Z used for representing migration electron number, T used for representing absolute temperature of a target battery at the current time, F used for representing Faraday constant, and->
For characterizing the electrode reaction concentration ratio of the target cell.
Further, the formula for determining the target ohmic internal resistance value of the second-order equivalent circuit model is specifically as follows:
wherein, |U1-U2I is used for representing the instantaneous abrupt change end voltage difference of the target battery which appears in the pulse just-generated stage when the target battery is discharged, U3-U4I is used for representing the instantaneous abrupt change end voltage difference of the target battery which appears after the pulse is ended when the target battery is discharged, I is used for representing the pulse current, A is used for representing the frequency factor, m is used for representing the constant term, E 0 And R is used for representing the apparent activation energy constant, R is used for representing the molar gas constant, T is used for representing the absolute temperature of the target battery at the current time, R0 is used for representing the initial ohmic internal resistance value of the second-order equivalent circuit model, and y (RO) is used for representing the target ohmic internal resistance value of the second-order equivalent circuit model.
Further, the formula for determining the target ohmic voltage value corresponding to the target ohmic internal resistance value is as follows:
U R ＝y(RO)I；
wherein I is used for representing pulse current, U R And y (RO) is used for representing a target ohmic voltage value and a target ohmic internal resistance value of the second-order equivalent circuit model.
Further, the first voltage value and the second voltage value together constitute a polarization voltage value, which is determined by:
determining an overpotential in a second-order equivalent circuit model based on a preset butler-fomer equation, current density in the second-order equivalent circuit model, exchange current density in the second-order equivalent circuit model and temperature of a target battery at a current time;
determining polarization internal resistances 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;
and determining a polarization voltage value according to the polarization internal resistance and the pulse current in the target battery.
The embodiment of the application also provides an output voltage determining device of a second-order equivalent circuit model, which comprises:
the first determining module is used for determining a target open-circuit voltage value of a second-order equivalent circuit model based on an initial open-circuit voltage value of the second-order equivalent circuit model corresponding to the 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 when the target battery to be detected discharges;
the second determining module is used for 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 based on an initial ohmic internal 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 the third determining module is used for determining 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.
Further, the formula for determining the target open circuit voltage value of the second-order equivalent circuit model is specifically as follows:
wherein Uocv is used for representing a target open circuit voltage value of the second-order equivalent circuit model,
the initial open circuit voltage value used for representing the second-order equivalent circuit model is R used for representing molar gas constant, Z used for representing migration electron number, T used for representing absolute temperature of a target battery at the current time, F used for representing Faraday constant, and->
For characterizing the electrode reaction concentration ratio of the target cell.
Further, the formula for determining the target ohmic internal resistance value of the second-order equivalent circuit model is specifically as follows:
wherein, I U1-U2I is used for representing the instantaneous abrupt change end voltage difference of the target battery in the discharge period of the pulse immediately after generation, I U3-U4I is used for representing the instantaneous abrupt change end voltage difference of the target battery in the discharge period of the pulse, I is used for representing the pulse current, A is used for representing the frequency factor, m is used for representing the constant term, E 0 And R is used for representing the apparent activation energy constant, R is used for representing the molar gas constant, T is used for representing the absolute temperature of the target battery at the current time, R0 is used for representing the initial ohmic internal resistance value of the second-order equivalent circuit model, and y (RO) is used for representing the target ohmic internal resistance value of the second-order equivalent circuit model.
The embodiment of the application also provides electronic equipment, which comprises: the system comprises a processor, a memory and a bus, wherein the memory stores machine-readable instructions executable by the processor, the processor and the memory are communicated through the bus when the electronic device runs, and the machine-readable instructions are executed by the processor to execute the steps of the output voltage determining method of the second-order equivalent circuit model.
The embodiments of the present application also provide a computer readable storage medium having stored thereon a computer program which, when executed by a processor, performs the steps of the output voltage determining method of the second-order equivalent circuit model as described above.
Compared with the prior art, the method and the device for determining the output voltage of the second-order equivalent circuit model provided by the embodiment of the application determine 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, determine the target 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, determine the target ohmic internal resistance value of the second-order equivalent circuit model corresponding to the target ohmic internal resistance value, and then 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, so that the model parameters of the traditional lithium ion battery are inaccurate due to temperature change, and the accuracy of the model is improved.
In order to make the above objects, features and advantages of the present application more comprehensible, preferred embodiments accompanied with figures are described in detail below.
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In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the embodiments will be briefly described below, it being understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered limiting the scope, and that other related drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a flow chart of a method for determining an output voltage of a second-order equivalent circuit model according to an embodiment of the present application;
fig. 2 is a schematic structural diagram of an output voltage determining device of a second-order equivalent circuit model according to an embodiment of the present application;
fig. 3 shows a circuit configuration diagram of a second-order equivalent circuit model in the output voltage determining method of the second-order equivalent circuit model according to the embodiment of the present application;
fig. 4 shows a schematic structural diagram of an electronic device according to an embodiment of the present application.
In the figure:
200-output voltage determining means; 210-a first determination module; 220-a second determination module; 230-a third determination module; OCV-open circuit voltage source; r0-ohm internal resistance; r1-first polarization internal resistance; r2-second polarized internal resistance; c1-a first polarization capacitor; c2-a second polarized capacitor; 400-an electronic device; 410-a processor; 420-memory; 430-bus.
Detailed Description
For the purposes of making the objects, 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 clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is apparent that the described embodiments are only some embodiments of the present application, but not all embodiments. The components of the embodiments of the present application, which are generally described and illustrated in the figures herein, may be arranged and designed in a wide variety of different configurations. Thus, the following detailed description of the embodiments of the present application, as provided in the accompanying drawings, is not intended to limit the scope of the application, as claimed, but is merely representative of selected embodiments of the application. Based on the embodiments of the present application, every other embodiment that a person skilled in the art would obtain without making any inventive effort is within the scope of protection of the present application.
First, application scenarios applicable to the present application will be described. The method and the device can be applied to the technical field of new energy batteries.
The research shows that the internal reaction of the lithium ion battery has the characteristics of high nonlinearity and time variation, the internal parameters of the lithium ion battery are influenced by a plurality of factors to cause the change of the output voltage of the battery terminal, and the model precision of the equivalent circuit model of the traditional lithium ion battery is lower.
Conventional battery models for lithium ion batteries fall into three general categories: electrochemical models, neural network models and equivalent circuit models, wherein the electrochemical models have high model precision and can describe chemical reactions inside the battery, but the electrochemical models are difficult to identify all parameters; the neural network model has higher classification accuracy for the battery and can fully clear the complex nonlinear relation, but the neural network needs a large amount of parameter acquisition; the equivalent circuit model has a simple structure, so that the embodiment of the application is researched aiming at the equivalent circuit model of the lithium ion battery.
In the above, the temperature change of the battery can be affected by the electric automobile in different working environment temperatures and discharging states, but in the battery operation state of the traditional lithium ion battery, the influence of the temperature change on the internal parameters of the battery and the accuracy of the battery cannot be fully considered.
Based on the above, the embodiment of the application provides a method and a device for determining the output voltage of a second-order equivalent circuit model, which solve the problem of inaccurate model parameters of the traditional lithium ion battery caused by temperature change, thereby improving the accuracy of the model.
Referring to fig. 1, fig. 1 is a flowchart of a method for determining an output voltage of a second-order equivalent circuit model according to an embodiment of the present application. As shown in fig. 1, the output voltage determining method of the second-order equivalent circuit model provided in the embodiment of the application includes the following steps:
s101, when a target battery to be detected discharges, determining a target open circuit voltage value of a second-order equivalent circuit model based on an initial open circuit voltage value of the second-order equivalent circuit model corresponding to the 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.
In the step, when the target battery to be detected is determined to be discharged, the influence of temperature change on the internal parameters of the target battery and the battery precision 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 and other parameter values of the second-order equivalent circuit model corresponding to the target battery.
Here, compared with other equivalent circuit models, the embodiment provided by the application has clear physical meaning and high model precision, and can simulate the dynamic characteristics of the target battery more accurately and intuitively.
The second-order equivalent circuit model in the embodiment provided by the application obtains the initial open-circuit voltage value, the electrode reaction concentration ratio of the target battery, the temperature of the target battery at the current moment and other parameters through a target integrated circuit (System on Chip, SOC).
In this way, the embodiment provided by the application uses the hybrid power pulse characteristic (Hybrid PulsePower Characteristic, HPPC) to test the target battery to be tested, obtains the relation 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 tests is 10%, in order to obtain the SOC-OCV relation, adopts the small-scale constant current to discharge, and discharges the target battery for multiple times to the preset cut-off voltage, and before the target battery enters the next pulse, the target battery needs to stand for a period of time to restore to a relatively stable state.
In the foregoing, the preset cutoff voltage in the embodiment provided in the present application may be selected in a self-defined manner according to different materials of the target battery, specifically:
if the target battery is an iron lithium ion battery, the preset cut-off voltage is 2-3.65V.
If the target battery is a ternary lithium ion battery, the preset cutoff voltage is 3-4.2V.
Optionally, the formula for determining the target open circuit voltage value of the second-order equivalent circuit model is specifically:
wherein Uocv is used for representing a target open circuit voltage value of the second-order equivalent circuit model,
the initial open circuit voltage value used for representing the second-order equivalent circuit model is R used for representing molar gas constant, Z used for representing migration electron number, T used for representing absolute temperature of a target battery at the current time, F used for representing Faraday constant, and->
For characterizing the electrode reaction concentration ratio of the target cell.
In the above, in a state where the target battery is discharged using the current preset multiplying power, the value of the initial open-circuit voltage value under the preset typical condition is obtained, and the initial open-circuit voltage value is independent of the temperature, but is closely related to the SOC, and is determined by the SOC of the target battery.
Here, the preset nernst equation refers to an equation expression for quantitatively describing a diffusion potential of a certain ion formed between the two systems a and B.
S102, 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 based on an initial ohmic internal resistance value of the second-order equivalent circuit model corresponding to the target battery, a preset Arrhenius equation and a preset three-parameter equation.
In the step, during the pulse process of discharging the target battery to be detected, the battery terminal voltage of the target battery to be detected suddenly drops, the sudden drop is regarded as the voltage drop generated on the ohmic internal resistance, the voltage rising rate is extremely fast at the end of discharging and is similar to the sudden drop in time in the discharging process, and at the moment, the process of generating the voltage sudden drop is determined as the process of disappearing the ohmic internal resistance.
In the above, since the preset Arrhenius equation is greatly loud and the absolute linear relationship does not exist when the Arrhenius equation takes the logarithm, the preset three-parameter equation used for correction needs to be introduced to determine the influence of the temperature at the current time on the ohmic internal resistance value, the preset Arrhenius equation is suitable for a temperature range in a smaller range, and the preset three-parameter equation is suitable for a wider temperature range.
The formula for determining the target ohmic internal resistance value of the second-order equivalent circuit model is specifically as follows:
the method comprises the steps of (1) representing an instantaneous abrupt change end voltage difference of a target battery in a pulse generation stage when the target battery is discharged, (3) representing an instantaneous abrupt change end voltage difference of the target battery in a pulse generation stage when the target battery is discharged, (4) representing a pulse current after the pulse is ended, (0) representing an apparent activation energy constant, and (0) representing a molar gas constant, wherein (1-U) represents an absolute temperature of the target battery in a current time, R0 represents an initial ohmic internal resistance value of a second-order equivalent circuit model, and (y) represents a target ohmic internal resistance value of the second-order equivalent circuit model.
In the above, in a state that the target battery is discharged by using the current preset multiplying power, the value of the initial ohmic internal resistance value under the preset typical condition is obtained, and the initial ohmic internal resistance value is corrected by adopting a preset three-parameter equation.
Thus, the ohmic internal resistance mainly consists of electrode materials, electrolyte, diaphragm resistance and contact resistance of parts, and is related to the size, structure, assembly and the like of the battery.
In the above description, the logarithmic processing is performed on y (RO), and the specific formula is as follows:
optionally, the formula for determining the target ohmic voltage value corresponding to the target ohmic internal resistance value is:
U R ＝y(RO)I；
wherein I is used for representing pulse current, U R And y (RO) is used for representing a target ohmic voltage value and a target ohmic internal resistance value of the second-order equivalent circuit model.
And S103, determining 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.
In the step, in the pulse discharging process of the target battery, the voltage is reduced in an exponential state, when the battery is in a standing process, no external input exists, parameters of a first RC circuit and a second RC circuit are obtained at the stage, the parameters are obtained through a fitting method, and the voltage response relation formula is as follows:
in the above, the formula of the first voltage value in the first RC circuit specifically includes:
Up1＝U10e -t/τ1 ＝R1×I×e -t/τ1 ；
thus, τ is used to characterize the time constant, τ1=r1×c1, t is used to characterize the time, up is used to characterize the voltage trend at the target cell polarization, i.e., at the rest phase (current 0).
In the above, the formula of the second voltage value in the second RC circuit is specifically:
Up2＝U20e -t/τ1 ＝R2×I×e -t/τ1 ；
thus, τ is used to characterize the time constant, τ2=r2×c2, t is used to characterize the time, up is used to characterize the voltage trend at the target cell polarization at the rest phase (current 0).
Up＝U10e -t/τ1 +U20e -t/τ2 ；
Wherein, up is used for representing the change trend of the battery polarization voltage in the standing stage (current is 0).
Optionally, determining a polarization voltage value by the substep of:
substep 1031, determining an overpotential in the second-order equivalent circuit model based on a preset butler-former 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.
In this step, the influence of absolute temperature and pulse current on the internal resistance of polarization and overpotential is determined according to the butler-fommer equation under consideration of the diffusion process and the charge transfer process.
In the above description, the preset butler-foremerer equation is specifically:
wherein J is used to characterize the current density, J0 is used to characterize the switching current density,
and->
The O end and the R end at two ends of the electrode are respectively used for representing the supply of the O end and the R end through liquid phase mass transfer, delta phi is used for representing the overpotential, and beta is used for representing a constant term.
Of the above, j 0 The formula of (2) is specifically:
wherein ΔΦ=Φ - Φ e ，Φ e For characterizing the equilibrium potential, Φ' for characterizing the reference potential, Φ for characterizing the polarization potential of the electrode at the current time.
In the above description exp is used to characterize the exponential function put based on the natural constant e.
Here the number of the elements is the number,
i.e. phi e Is greatly affected by temperature.
Sub-step 1032, determining internal polarization resistances in the first and second RC circuits from the overpotential and the pulsed current in the second order equivalent circuit model.
In the above description, the polarized internal resistance in the first RC circuit or the polarized internal resistance in the second RC circuit is used to represent the polarized internal resistance value when the electrode potential deviates from its equilibrium value when a (net) current flows through the electrode, and can be further divided into anodic polarization and cathodic polarization according to the direction of the pulse current.
The formula of anodic polarization is specifically:
wherein ΔΦ a For characterizing the anodic overpotential.
The formula of cathode polarization is specifically:
wherein ΔΦ c The method is used for representing the cathode polarization overpotential, wherein the first term is an electrochemical polarization term, and the last term is a concentration polarization term.
In the above description, when Φ e When the change occurs, the pulse is rapidly increased, the index term is larger, the liquid phase mass transfer term is smaller, and electrochemical polarization mainly occurs at the moment; under the condition of large delta phi difference, the pulse tends to be stable, and concentration polarization mainly occurs at the moment when the current is determined by the process of liquid phase mass transfer due to large ratio of the surface concentration to the bulk concentration.
Substep 1033, determining a polarization voltage value based on said polarization internal resistance and said pulse current in the target battery.
In the above description, the output voltage of the second-order equivalent circuit model corresponding to the target battery in the discharge state is specifically:
and the U is used for representing the output voltage of the second-order equivalent circuit model corresponding to the target battery at the current moment.
Compared with the prior art, the output voltage determining method of the second-order equivalent circuit model provided by the embodiment of the application 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 corresponding to the target battery, the preset Arrhenius equation and the preset three-parameter equation, determines the target ohmic internal resistance value of the second-order equivalent circuit model and the target ohmic internal resistance value of the second-order equivalent circuit model, 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, so that the model parameters of the traditional lithium ion battery are inaccurate due to temperature change, and the accuracy of the model is improved.
Referring to fig. 2, fig. 2 is a schematic structural diagram of an output voltage determining device of a second-order equivalent circuit model according to an embodiment of the present application. As shown in fig. 2, the output voltage determining apparatus 200 of the second-order equivalent circuit model provided in the embodiment of the present application includes:
the first determining module 210 is configured to determine, when a target battery to be detected is discharged, a target open circuit voltage value of a second-order equivalent circuit model corresponding to the 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 time, and a preset nernst equation.
Optionally, the formula for determining the target open circuit voltage value of the second-order equivalent circuit model in the first determining module 210 is specifically:
wherein Uocv is used for representing a target open circuit voltage value of the second-order equivalent circuit model,
the initial open circuit voltage value used for representing the second-order equivalent circuit model is R used for representing molar gas constant, Z used for representing migration electron number, T used for representing absolute temperature of a target battery at the current time, F used for representing Faraday constant, and->
For characterizing the electrode reaction concentration ratio of the target cell.
The second determining module 220 is configured to determine 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 based on an initial ohmic internal resistance value of the second-order equivalent circuit model corresponding to the target battery, a preset Arrhenius equation and a preset three-parameter equation.
Optionally, the formula for determining the target ohmic internal resistance value of the second-order equivalent circuit model in the second determining module 220 is specifically as follows:
wherein, I U1-U2I is used for representing the instantaneous abrupt change end voltage difference of the target battery in the discharge period of the pulse immediately after generation, I U3-U4I is used for representing the instantaneous abrupt change end voltage difference of the target battery in the discharge period of the pulse, I is used for representing the pulse current, A is used for representing the frequency factor, m is used for representing the constant term, E 0 And R is used for representing the apparent activation energy constant, R is used for representing the molar gas constant, T is used for representing the absolute temperature of the target battery at the current time, R0 is used for representing the initial ohmic internal resistance value of the second-order equivalent circuit model, and y (RO) is used for representing the target ohmic internal resistance value of the second-order equivalent circuit model.
Optionally, the formula for determining the target ohmic voltage value corresponding to the target ohmic internal resistance value in the second determining module 220 is:
U R ＝y(RO)I；
wherein I is used for representing pulse current, U R And y (RO) is used for representing a target ohmic voltage value and a target ohmic internal resistance value of the second-order equivalent circuit model.
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 the current time 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.
Optionally, the first voltage value and the second voltage value together form a polarization voltage value, and the polarization voltage value is determined by:
and determining the overpotential in the second-order equivalent circuit model based on a preset butler-Fabry 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.
And determining the polarization internal resistances 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.
And determining a polarization voltage value according to the polarization internal resistance and the pulse current in the target battery.
Compared with the prior art, the output voltage determining device 200 provided in the embodiment of the present application 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 time 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 time 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 improving the accuracy of the model.
According to the embodiment provided by the application, the influence of temperature on the open-circuit voltage source, the ohmic internal resistance and the polarization internal resistance is researched through the preset Arrhenius equation, the preset Nernst equation and the preset Butler-Fummer equation, the problem that the model parameters of the traditional lithium ion battery are inaccurate due to temperature change is solved, and the accuracy of the model is further improved.
Referring to fig. 3, fig. 3 is a circuit diagram of a second-order equivalent circuit model in the output voltage determining method of the second-order equivalent circuit model according to the embodiment of the present application. As shown in fig. 3, the second-order equivalent circuit model includes an open-circuit voltage source OCV, an ohmic internal resistance R0, a first polarized internal resistance R1, a first polarized capacitor C1, a second polarized internal resistance R2, and a second polarized capacitor C2, wherein the positive terminal of the open-circuit voltage source OCV is electrically connected to one terminal of the first polarized internal resistance R1 and one terminal of the first polarized capacitor C1 through one ohmic internal resistance R0, the other terminal of the first polarized internal resistance R1 is electrically connected to one terminal of the second polarized internal resistance R2, the other terminal of the first polarized capacitor C1 is electrically connected to one terminal of the second polarized capacitor C2, the first polarized capacitor C1 is electrically connected to the first polarized internal resistance R1 in parallel, the second polarized capacitor C2 is electrically connected to the second polarized internal resistance R2, and the other terminal of the second polarized internal resistance R2 is electrically connected to the negative terminal of the open-circuit voltage source OCV.
Referring to fig. 4, fig. 4 is a schematic structural diagram of an electronic device according to an embodiment of the present application. As shown in fig. 4, the electronic device 400 includes a processor 410, a memory 420, and a bus 430.
The memory 420 stores machine-readable instructions executable by the processor 410, when the electronic device 400 is running, the processor 410 communicates with the memory 420 through the bus 430, and when the machine-readable instructions are executed by the processor 410, the steps of the output voltage determining method of the second-order equivalent circuit model in the method embodiments shown in fig. 1 and fig. 2 can be executed, and detailed implementation manners may refer to method embodiments and are not repeated herein.
The embodiment of the present application further provides a computer readable storage medium, where a computer program is stored on the computer readable storage medium, and when the computer program is executed by a processor, the steps of the method for determining an output voltage of a second-order equivalent circuit model in the method embodiments shown in fig. 1 and fig. 2 may be executed, and a specific implementation manner may refer to the method embodiment and will not be described herein.
It will be clear to those skilled in the art that, for convenience and brevity of description, specific working procedures of the above-described systems, apparatuses and units may refer to corresponding procedures in the foregoing method embodiments, and are not repeated herein.
In the several embodiments provided in this application, it should be understood that the disclosed systems, devices, and methods may be implemented in other manners. The above-described apparatus embodiments are merely illustrative, for example, the division of the units is merely a logical function division, and there may be other manners of division in actual implementation, and for example, multiple units or components may be combined or integrated into another system, or some features may be omitted, or not performed. Alternatively, the coupling or direct coupling or communication connection shown or discussed with each other may be through some communication interface, device or unit indirect coupling or communication connection, which may be in electrical, mechanical or other form.
The units described as separate units may or may not be physically separate, and units shown as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.
In addition, each functional unit in each embodiment of the present application may be integrated in one processing unit, or each unit may exist alone physically, or two or more units may be integrated in one unit.
The functions, if implemented in the form of software functional units and sold or used as a stand-alone product, may be stored in a non-volatile computer readable storage medium executable by a processor. Based on such understanding, the technical solution of the present application may be embodied essentially or in a part contributing to the prior art or in a part of the technical solution, in the form of a software product stored in a storage medium, including several instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the methods described in the embodiments of the present application. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a random access Memory (Random Access Memory, RAM), a magnetic disk, or an optical disk, or other various media capable of storing program codes.
Finally, it should be noted that: the foregoing examples are merely specific embodiments of the present application, and are not intended to limit the scope of the present application, but the present application is not limited thereto, and those skilled in the art will appreciate that while the foregoing examples are described in detail, the present application is not limited thereto. Any person skilled in the art may modify or easily conceive of the technical solution described in the foregoing embodiments, or make equivalent substitutions for some of the technical features within the technical scope of the disclosure of the present application; such modifications, changes or substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present application, and are intended to be included in the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.
Claims (10)
1. The output voltage determining method of the second-order equivalent circuit model is characterized by comprising the following steps of:
when a target battery to be detected discharges, determining a target open-circuit voltage value of a second-order equivalent circuit model based on an initial open-circuit voltage value of the second-order equivalent circuit model corresponding to the 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 based on an initial ohmic internal 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 determining 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.
2. The method for determining the output voltage of the second-order equivalent circuit model according to claim 1, wherein the formula for determining the target open-circuit voltage value of the second-order equivalent circuit model is specifically:
wherein Uocv is used for representing a target open circuit voltage value of the second-order equivalent circuit model,
the initial open circuit voltage value used for representing the second-order equivalent circuit model is R used for representing molar gas constant, Z used for representing migration electron number, T used for representing absolute temperature of a target battery at the current time, F used for representing Faraday constant, and->
For characterizing the electrode reaction concentration ratio of the target cell.
3. The method for determining the output voltage of the second-order equivalent circuit model according to claim 1, wherein the formula for determining the target ohmic internal resistance value of the second-order equivalent circuit model is specifically as follows:
wherein, I U1-U2I is used for representing the instantaneous abrupt change end voltage difference of the target battery which appears in the pulse generation stage when discharging, I3-U4I is used for representing the instantaneous abrupt change end voltage difference of the target battery which appears after the pulse is ended when discharging, I is used for representing the pulse current, A is used for representing the frequency factor, m is used for representing the constant term, E 0 And R is used for representing the apparent activation energy constant, R is used for representing the molar gas constant, T is used for representing the absolute temperature of the target battery at the current time, R0 is used for representing the initial ohmic internal resistance value of the second-order equivalent circuit model, and y (RO) is used for representing the target ohmic internal resistance value of the second-order equivalent circuit model.
4. The method for determining an output voltage of a second-order equivalent circuit model according to claim 3, wherein the formula for determining the target ohmic voltage value corresponding to the target ohmic internal resistance value is:
U R ＝y(RO)I；
wherein I is used for representing pulse current, U R And y (RO) is used for representing a target ohmic voltage value and a target ohmic internal resistance value of the second-order equivalent circuit model.
5. The method of determining an output voltage of a second-order equivalent circuit model according to claim 1, wherein the first voltage value and the second voltage value together constitute a polarization voltage value, the polarization voltage value being determined by:
determining an overpotential in a second-order equivalent circuit model based on a preset butler-fomer equation, current density in the second-order equivalent circuit model, exchange current density in the second-order equivalent circuit model and temperature of a target battery at a current time;
determining polarization internal resistances 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;
and determining a polarization voltage value according to the polarization internal resistance and the pulse current in the target battery.
6. An output voltage determining device of a second-order equivalent circuit model, characterized in that the output voltage determining device of the second-order equivalent circuit model comprises:
the first determining module is used for determining a target open-circuit voltage value of a second-order equivalent circuit model based on an initial open-circuit voltage value of the second-order equivalent circuit model corresponding to the 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 when the target battery to be detected discharges;
the second determining module is used for 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 based on an initial ohmic internal 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 the third determining module is used for determining 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 determining apparatus of a second-order equivalent circuit model according to claim 6, wherein the formula for determining the target open-circuit voltage value of the second-order equivalent circuit model is specifically:
wherein Uocv is used for representing a target open circuit voltage value of the second-order equivalent circuit model,
the initial open circuit voltage value used for representing the second-order equivalent circuit model is R used for representing molar gas constant, Z used for representing migration electron number, T used for representing absolute temperature of a target battery at the current time, F used for representing Faraday constant, and->
For characterizing the electrode reaction concentration ratio of the target cell.
8. The output voltage determining apparatus of a second-order equivalent circuit model according to claim 6, wherein the formula for determining the target ohmic internal resistance value of the second-order equivalent circuit model is specifically as follows:
wherein, U1-U2 is used for representing the instantaneous abrupt change end voltage difference of the pulse just generated stage when the target battery is discharged, and U3-U4 is usedWhen the target battery is represented to be discharged, the instantaneous abrupt change end voltage difference appears after the pulse is ended, wherein I is used for representing pulse current, A is used for representing frequency factors, m is used for representing constant items, E 0 And R is used for representing the apparent activation energy constant, R is used for representing the molar gas constant, T is used for representing the absolute temperature of the target battery at the current time, R0 is used for representing the initial ohmic internal resistance value of the second-order equivalent circuit model, and y (RO) is used for representing the target ohmic internal resistance value of the second-order equivalent circuit model.
9. An electronic device, comprising: a processor, a memory and a bus, said memory storing machine readable instructions executable by said processor, said processor and said memory communicating via the bus when the electronic device is running, said machine readable instructions when executed by said processor performing the steps of the method of determining an output voltage of a second order equivalent circuit model as defined in any one of the preceding claims 1 to 5.
10. A computer-readable storage medium, characterized in that the computer-readable storage medium has stored thereon a computer program which, when executed by a processor, performs the steps of the output voltage determination method of the second-order equivalent circuit model as claimed in any one of the preceding claims 1 to 5.
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