CN113447826B - SOC determination method and device based on steady-state equivalent circuit model - Google Patents
SOC determination method and device based on steady-state equivalent circuit model Download PDFInfo
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- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/36—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/36—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
- G01R31/382—Arrangements for monitoring battery or accumulator variables, e.g. SoC
- G01R31/3842—Arrangements for monitoring battery or accumulator variables, e.g. SoC combining voltage and current measurements
Abstract
The embodiment of the invention provides a SOC (system on chip) determination method and device based on a steady-state equivalent circuit model, wherein the method comprises the following steps: acquiring current charging/discharging current, current steady-state voltage and current working temperature corresponding to a target battery in a steady state in the running process of a target vehicle; determining corresponding steady-state voltages under different SOCs from a steady-state equivalent circuit model database corresponding to the target battery based on the current charging/discharging current and the current working temperature; and determining the current SOC of the target battery based on the relation between the current steady-state voltage and the corresponding steady-state voltages under different SOCs. By utilizing the steady-state equivalent circuit model database, the steady-state voltages under different SOCs corresponding to the current charging/discharging current and the current working temperature of the target battery in a steady state are searched, and the current SOC of the target battery is determined by comparing the current steady-state voltage with the steady-state voltages under different SOCs. The whole scheme has small calculation amount, high precision and easy implementation.
Description
Technical Field
The invention relates to the technical field of batteries, in particular to a SOC (state of charge) determination method and device based on a steady-state equivalent circuit model.
Background
The SOC is an important parameter when the electric automobile runs, accurate estimation of the SOC is important, functions in a battery management system, such as overcharge and overdischarge protection, electric quantity equalization, fault detection and the like, are predicated on the SOC, but the SOC is not a directly measured physical quantity and is obtained through tests or estimation. At present, there are many methods for estimating SOC, such as a discharge experiment method, an internal resistance method, an open-circuit voltage testing method, a current integration method, a neural network method, a kalman filter method, and the like.
However, in the existing methods, a discharge experiment method cannot be performed on a real vehicle, an internal resistance method needs internal resistance, but the accurate measurement difficulty of the internal resistance of a battery core is high, an open-circuit voltage method needs to be kept still for a long time, the method is difficult to apply when a real vehicle battery is in a working state, an error exists in the calculation of the SOC by a current integration method, the error needs to be periodically corrected, and otherwise, the error is larger and larger; the neural network method relies on a large amount of accurate sample data and a proper neural network model; the kalman filtering method requires a high accuracy of the battery model and a large calculation amount. Therefore, how to conveniently and accurately determine the SOC of the battery in the real vehicle in the working state becomes an urgent problem to be solved.
Disclosure of Invention
In view of this, embodiments of the present invention provide a method and an apparatus for determining an SOC based on a steady-state equivalent circuit model, so as to overcome a problem in the prior art that it is difficult to conveniently and accurately determine an SOC of a battery in a real vehicle in a working state.
The embodiment of the invention provides a SOC (state of charge) determination method based on a steady-state equivalent circuit model, which comprises the following steps:
acquiring current charging/discharging current, current steady-state voltage and current working temperature corresponding to a target battery in a steady state in the running process of a target vehicle;
determining corresponding steady-state voltages under different SOCs from a steady-state equivalent circuit model database corresponding to the target battery based on the current charging/discharging current and the current working temperature, wherein the steady-state equivalent circuit model database stores the relationships between the charging/discharging current, the working temperature and the steady-state voltages under different SOCs established based on a steady-state equivalent circuit model of the target battery;
and determining the current SOC of the target battery based on the relation between the current steady-state voltage and the corresponding steady-state voltages under different SOCs.
Optionally, the determining the current SOC of the target battery based on the relationship between the current steady-state voltage and the corresponding steady-state voltages at different SOCs includes:
acquiring a first steady-state voltage closest to the current steady-state voltage from corresponding steady-state voltages under different SOC;
and determining the SOC corresponding to the first steady-state voltage as the current SOC of the target battery.
Optionally, the method further comprises:
acquiring a steady-state equivalent circuit model corresponding to the target battery;
based on the working parameter conditions of the target battery, performing charge and discharge tests on the steady-state equivalent circuit model under different SOC to obtain corresponding charge/discharge voltage, wherein the working parameter conditions comprise: working temperature range, charge/discharge current range;
calculating to obtain charging/discharging internal resistances and charging/discharging electromotive forces corresponding to different working parameter conditions based on corresponding charging/discharging voltages under different working parameter conditions;
calculating corresponding charging/discharging steady-state voltage based on charging/discharging internal resistance and charging/discharging electromotive force corresponding to different working parameter conditions under different SOC;
and constructing the steady-state equivalent circuit model database based on the corresponding relation between different working parameter conditions and charging/discharging steady-state voltages under different SOCs.
Optionally, before obtaining a current charge/discharge current, a current steady-state voltage, and a current operating temperature corresponding to a target battery in a steady state during operation of the target vehicle, the method further includes:
collecting the charging/discharging current of the target battery according to a preset period when the target battery is in a working state;
acquiring the maximum charge/discharge current, the minimum charge/discharge current and the average charge/discharge current of the target battery in the current preset period;
judging whether the relationship among the maximum charge/discharge current, the minimum charge/discharge current and the average charge/discharge current meets the steady-state working relationship of the battery or not;
and when the relationship among the maximum charge/discharge current, the minimum charge/discharge current and the average charge/discharge current meets the steady-state working relationship of the battery, determining that the target battery is in a steady state.
Optionally, the method further comprises:
determining the working state of the target battery based on the charging/discharging current of the target battery in the current preset period, wherein the working state comprises the following steps: a charged state and a discharged state.
Optionally, the obtaining a first steady-state voltage closest to the current steady-state voltage from corresponding steady-state voltages under different SOCs includes:
and acquiring a first steady-state voltage which is the same as and closest to the current steady-state voltage in working state from corresponding steady-state voltages under different SOC based on the working state of the target battery.
Optionally, the calculating, based on the charging/discharging voltages corresponding to different operating parameters, the charging/discharging internal resistances and the charging/discharging electromotive forces corresponding to different operating parameters includes:
acquiring charging/discharging voltage corresponding to the first charging/discharging current and the second charging/discharging current at the current temperature;
calculating the mean value of the charging/discharging currents of the first charging/discharging current and the second charging/discharging current, and determining the current charging/discharging current;
and calculating the current charging/discharging internal resistance and the charging/discharging electromotive force corresponding to the current charging/discharging current at the current temperature based on the charging/discharging voltage corresponding to the first charging/discharging current and the second charging/discharging current.
The embodiment of the invention also provides an SOC determination device based on the steady-state equivalent circuit model, which comprises:
the acquisition module is used for acquiring the current charging/discharging current, the current steady-state voltage and the current working temperature corresponding to the target battery in a steady state in the running process of the target vehicle;
the first processing module is used for determining corresponding steady-state voltages under different SOCs from a steady-state equivalent circuit model database corresponding to the target battery based on the current charging/discharging current and the current working temperature, and the steady-state equivalent circuit model database stores the relationships between the charging/discharging current, the working temperature and the steady-state voltages under different SOCs established based on a steady-state equivalent circuit model of the target battery;
and the second processing module is used for determining the current SOC of the target battery based on the relation between the current steady-state voltage and the corresponding steady-state voltages under different SOCs.
An embodiment of the present invention further provides an electronic device, including: the device comprises a memory and a processor, wherein the memory and the processor are connected with each other in a communication mode, computer instructions are stored in the memory, and the processor executes the computer instructions so as to execute the method provided by the embodiment of the invention.
The embodiment of the invention also provides a computer-readable storage medium, which stores computer instructions for enabling a computer to execute the method provided by the embodiment of the invention.
The technical scheme of the invention has the following advantages:
the embodiment of the invention provides a method and a device for determining SOC (state of charge) based on a steady-state equivalent circuit model, which are characterized in that the method comprises the steps of obtaining the corresponding current charge/discharge current, the current steady-state voltage and the current working temperature when a target battery is in a steady state in the running process of a target vehicle; determining corresponding steady-state voltages under different SOCs from a steady-state equivalent circuit model database corresponding to the target battery based on the current charging/discharging current and the current working temperature; and determining the current SOC of the target battery based on the relation between the current steady-state voltage and the corresponding steady-state voltages under different SOCs. Therefore, by utilizing a steady-state equivalent circuit model database which stores the relationship among the charging/discharging current, the working temperature and the steady-state voltage under different SOCs and is established based on the steady-state equivalent circuit model of the target battery, the steady-state voltages under different SOCs corresponding to the current charging/discharging current and the current working temperature when the target battery is in a steady state are searched, and the current SOC of the target battery is determined by comparing the current steady-state voltage with the steady-state voltages under different SOCs. Therefore, the SOC can be effectively corrected in the running process of the real vehicle, and the whole scheme is small in calculation amount, high in precision and easy to implement.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.
FIG. 1 is a flow chart of a steady-state equivalent circuit model-based SOC determination method in an embodiment of the present invention;
FIG. 2 is a schematic diagram of a steady-state equivalent circuit model of a target cell in an embodiment of the invention;
fig. 3 is a schematic structural diagram of an SOC determination apparatus based on a steady-state equivalent circuit model in an embodiment of the present invention;
fig. 4 is a schematic structural diagram of an electronic device in an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The technical features mentioned in the different embodiments of the invention described below can be combined with each other as long as they do not conflict with each other.
The SOC is an important parameter when the electric automobile runs, accurate estimation of the SOC is important, functions in a battery management system, such as overcharge and overdischarge protection, electric quantity equalization, fault detection and the like, are predicated on the SOC, but the SOC is not a directly measured physical quantity and is obtained through tests or estimation. At present, there are many methods for estimating SOC, such as a discharge experiment method, an internal resistance method, an open-circuit voltage testing method, a current integration method, a neural network method, a kalman filter method, and the like.
1. Principle of discharge experiment: the method comprises the steps that the battery is continuously discharged at a constant current under the condition that the battery has no load, the discharged amount is calculated when the discharging process reaches a limit, and the remaining capacity of the battery is the accumulated value of the discharging time and the discharging current. The discharge experiment method is generally used as a scheme for verifying the SOC accuracy.
2. The principle of the internal resistance method is as follows: the internal resistance of the battery can be obtained through the voltage and the current of the battery, and the SOC value of the battery is predicted according to the obtained internal resistance value due to the fact that a certain linear relation exists between the internal resistance of the battery and the SOC.
3. Open circuit voltage method principle: after the battery is left standing for a long time, the open-circuit voltage of the battery and the SOC form a certain relatively stable monotonic function relation, and the SOC value can be obtained by measuring the open-circuit voltage of the battery after the battery is left standing for a long time.
4. Principle of current integration method: the current integration method is also called ampere-hour integration method, and is a relatively common, simple and reliable SOC estimation method.
5. Principle of neural network method: the neural network can well process the nonlinear problem of multi-input single-output, the SOC is influenced by multi-input such as current, temperature, time and the like, the nonlinear relation is realized, a neural network model can be established, and the higher accuracy of SOC prediction is achieved through repeated training and correction of a large amount of sample data.
6. The principle of the Kalman filtering method is as follows: the SOC is used as an internal state variable of the battery management system by adopting a linear mean square criterion, the estimation at the last moment and the measured value obtained in real time are used for carrying out real-time estimation by a recursion method, and the SOC of the battery of the pure electric vehicle with severe current fluctuation in the driving process has a good prediction effect.
The discharge experiment method cannot be carried out on a real vehicle, so that the practical application significance is not great; the internal resistance method requires that the internal resistance and the SOC are in a monotone function relationship, and the internal resistance value needs to be accurately measured, the actual relationship between the SOC of the battery cell and the internal resistance is complex and is not in a monotone function relationship, and the accurate measurement of the internal resistance is difficult, so the actual significance is not great; the open-circuit voltage method needs to measure when the equal voltage tends to be stable, and needs to stand for a long time to achieve voltage stability, but the battery is difficult to show a stable state when working; the current integration method is an open-loop prediction, and as the system running time increases, errors gradually accumulate, so that the prediction of the SOC is inevitably inaccurate. The current accumulation integral is used for calculating the existence of errors, and the errors need to be corrected regularly, otherwise, the errors are larger and larger; the neural network method relies on a large amount of accurate sample data and a proper neural network model; the kalman filtering method requires a high accuracy of the battery model and a large calculation amount. Therefore, how to conveniently and accurately determine the SOC of the battery in the real vehicle in the working state becomes an urgent problem to be solved.
Based on the above problem, an embodiment of the present invention provides an SOC determination method based on a steady-state equivalent circuit model, and as shown in fig. 1, the SOC determination method based on the steady-state equivalent circuit model specifically includes the following steps:
step S101: and acquiring the current charging/discharging current, the current steady-state voltage and the current working temperature corresponding to the target battery in a steady state in the running process of the target vehicle.
The charging/discharging current, the steady-state voltage and the working temperature of the battery can be acquired by using corresponding monitoring equipment configured on an automobile in the prior art, and are not described herein again.
Specifically, when a target battery is in a working state, collecting the charge/discharge current of the target battery according to a preset period; acquiring the maximum charge/discharge current, the minimum charge/discharge current and the average charge/discharge current of a target battery in the current preset period; judging whether the relationship among the maximum charge/discharge current, the minimum charge/discharge current and the average charge/discharge current meets the steady-state working relationship of the battery or not; and when the relation among the maximum charge/discharge current, the minimum charge/discharge current and the average charge/discharge current meets the steady-state working relation of the battery, determining that the target battery is in a steady state. In the embodiment of the present invention, the preset period is 10s, but in practical applications, the preset period may also be flexibly set according to the requirement of the steady-state accuracy of the battery, and the present invention is not limited thereto.
Specifically, in an embodiment, the SOC determining method based on the steady-state equivalent circuit model provided in the embodiment of the present invention further includes: determining the working state of the target battery based on the charging/discharging current of the target battery in the current preset period, wherein the working state comprises the following steps: a charged state and a discharged state.
Illustratively, the battery can be considered to be in a steady state assuming that the current fluctuates less than 5% within 10s, and the sampling frequency is 1sThe process is as follows: when the battery is in working condition, tnT within 10s before the momentn-9、tn-8、tn-7、tn-6、tn-5、tn-4、tn-3、tn-2、tn-1、tnCorresponding currents are respectively In-9、In-8、In-7、In-6、In-5、In-4、In-3、In-2、In-1、InWhen all current values sampled in 10s are greater than 0, the battery is in a charging state, when all current values sampled in 10s are less than 0, the battery is in a discharging state, and the maximum value I of the current in 10s is respectively calculatedmaxMinimum value IminAnd average value ImeanIf Imax-Imin|/|Imean|<0.05, i.e. t can be considerednThe moment is steady state.
Step S102: and determining corresponding steady-state voltages under different SOCs from a steady-state equivalent circuit model database corresponding to the target battery based on the current charging/discharging current and the current working temperature.
The steady-state equivalent circuit model database stores the relationship among the charging/discharging current, the working temperature and the steady-state voltage under different SOC (system on chip) established based on the steady-state equivalent circuit model of the target battery.
Step S103: and determining the current SOC of the target battery based on the relation between the current steady-state voltage and the corresponding steady-state voltages under different SOCs.
Specifically, a first steady-state voltage closest to a current steady-state voltage is obtained from corresponding steady-state voltages under different SOCs; and determining the SOC corresponding to the first steady-state voltage as the current SOC of the target battery. Because a fixed function conversion relation exists between the SOC of the battery and the steady-state voltage under different working temperatures and charging/discharging currents, the SOC corresponding to the target battery in the real-vehicle running process can be accurately obtained by comparing the current steady-state voltage of the target battery with the steady-state voltage obtained by using a steady-state equivalent circuit model to perform charging and discharging tests.
Specifically, acquiring a first steady-state voltage closest to a current steady-state voltage from corresponding steady-state voltages under different SOCs specifically includes: and acquiring a first steady-state voltage which is the same as and closest to the current steady-state voltage in working state from corresponding steady-state voltages under different SOC based on the working state of the target battery. Illustratively, if the target battery is in a charging state during real vehicle operation, a charging steady-state voltage closest to the current steady-state voltage is obtained from corresponding steady-state voltages under different SOCs, and when the charging steady-state voltage is closer to the current steady-state voltage, the SOC corresponding to the charging steady-state voltage is also closer to the current steady-state voltage, so that accurate determination of the target battery SOC is realized by utilizing the consistency of the charging steady-state voltage and the current steady-state voltage.
By executing the above steps, the SOC determining method based on the steady-state equivalent circuit model according to the embodiment of the present invention searches for the steady-state voltages under different SOCs corresponding to the current charging/discharging current and the current operating temperature of the target battery in the steady state by using the steady-state equivalent circuit model database storing the relationships between the charging/discharging current, the operating temperature and the steady-state voltage under different SOCs established based on the steady-state equivalent circuit model of the target battery, and determines the current SOC of the target battery by comparing the current steady-state voltage with the steady-state voltages under different SOCs. Therefore, the SOC can be effectively corrected in the running process of the real vehicle, and the whole scheme is small in calculation amount, high in precision and easy to implement.
Specifically, in an embodiment, the process of establishing the steady-state equivalent circuit model database in step S102 specifically includes the following steps:
step S201: and acquiring a steady-state equivalent circuit model corresponding to the target battery.
Specifically, a corresponding steady-state equivalent circuit model is built according to the battery characteristics of the target battery, and the specific circuit model is shown in fig. 2, wherein EMF is electromotive force, R is internal resistance, I is current (charging is positive), and terminal voltage Ut = EMF + IR. Both EMF and R are affected by temperature, SOC, and current level.
Step S202: and carrying out charge and discharge tests on the steady-state equivalent circuit model under different SOC based on the working parameter conditions of the target battery to obtain corresponding charge/discharge voltage.
Wherein, the above-mentioned working parameter condition includes: operating temperature range, charge/discharge current range. Specifically, the operating temperature range and the charge/discharge current range of the target battery are specified by the target battery manufacturer at the time of shipment.
Step S203: and calculating to obtain the charging/discharging internal resistance and the charging/discharging electromotive force corresponding to different working parameter conditions based on the corresponding charging/discharging voltage under different working parameter conditions.
Specifically, the step S203 is implemented by obtaining a charge/discharge voltage corresponding to the first charge/discharge current and the second charge/discharge current at the current temperature; calculating the mean value of the charging/discharging currents of the first charging/discharging current and the second charging/discharging current, and determining the current charging/discharging current; and calculating the current charging/discharging internal resistance and the charging/discharging electromotive force corresponding to the current charging/discharging current at the current temperature based on the charging/discharging voltage corresponding to the first charging/discharging current and the second charging/discharging current.
Illustratively, the battery steady-state equivalent circuit model parameters EMF and R are first obtained by testing. The test method is as follows:
firstly, a series of temperature values T are selected according to the working temperature range and current range of the battery1,T2,…,TmSum current value C1,C2,…,Cn。
Secondly, a charging test and a discharging test are carried out by controlling the current and the temperature of the battery, the charging and discharging cut-off voltage respectively corresponds to the highest SOC and the lowest SOC of the battery, the selection of the current and the temperature refers to the step I, and a test matrix is shown in the table 1:
TABLE 1
| Current/temperature | T1 | T2 | … | Tm |
| C1 | Charging/discharging | Charging/discharging | Charging/discharging | Charging/discharging |
| C2 | Charging/discharging | Charging/discharging | Charging/discharging | Charging/discharging |
| … | Charging/discharging | Charging/discharging | Charging/discharging | Charging/discharging |
| Cn | Charging/discharging | Charging/discharging | Charging/discharging | Charging/discharging |
At T1At temperature by current C1And C2The charging test obtains a voltage Uc 1And Uc 2And calculating to obtain charging internal resistance R under different SOCc 1-2 = (Uc 1-Uc 2)/(C1-C2) Charged electromotive force EMFc 1-2 = Uc 1- C1Rc 1-2By analogy, T is obtainedmInternal resistance to charging at temperature Rc (n-1)-n = (Uc n-1-Uc n)/(Cn-1-Cn) Charged electromotive force EMFc (n-1)-n = Uc n-1- Cn-1Rc (n-1)-n(ii) a The same discharge test yields a voltage Ud 1And Ud 2Calculating to obtain discharging internal resistance R of different SOCd 1-2 = (Ud 1-Ud 2)/(C1-C2) Discharge electromotive force EMFd 1-2 = Ud 1- C1Rd 1-2By analogy, T is obtainedmInternal resistance to discharge at temperature Rd (n-1)-n = (Ud n-1-Ud n)/(Cn-1-Cn) Discharge electromotive force EMFd (n-1)-n = Ud n-1- Cn-1Rd (n-1)-n(ii) a The calculated data are shown in table 2:
TABLE 2
| Current/temperature | T1 | T2 | … | Tm |
| C1→C2 | EMF and R | EMF and R | EMF and R | EMF and R |
| C2→C3 | EMF and R | EMF and R | EMF and R | EMF and R |
| … | EMF and R | EMF and R | EMF and R | EMF and R |
| Cn-1→Cn | EMF and R | EMF and R | EMF and R | EMF and R |
Current C1And C2Taking the average to obtain I1=(C1+C2) /2, in turn, to give In-1=(Cn-1+Cn) And/2, obtaining a three-dimensional map of EMF and R by utilizing a linear interpolation and extrapolation method, namely the three-dimensional relation between EMF and working temperature, charging/discharging current and SOC during charging and discharging, and the three-dimensional relation between R and the working temperature, the charging/discharging current and the SOC during charging and discharging.
Step S204: and calculating corresponding charging/discharging steady-state voltage based on the charging/discharging internal resistance and the charging/discharging electromotive force corresponding to different working parameter conditions under different SOC.
Step S205: and constructing a steady-state equivalent circuit model database based on the corresponding relation between different working parameter conditions and charging/discharging steady-state voltages under different SOC.
Specifically, the current I is determined according to the charge-discharge state of the battery in a steady statenAnd temperature TnLooking up map under corresponding conditions in table 2 to obtain electromotive force EMF (SOC) and internal resistance R (SOC) under different SOCs, and calculating voltage U under different SOCst(SOC)=EMF(SOC)+InR (SOC) to obtain the current InAnd temperature TnLower UtAnd the SOC to form a steady-state equivalent circuit model database.
Exemplarily, the current I can also be measured according to the abovenAnd temperature TnLower UtFitting the monotonic function relation with SOC to obtain Ut= F (SOC), and the inverse function SOC = F (U)t) The current steady state voltage U corresponding to the real vehiclenSubstitution function SOC = F (U)t) The SOC at this steady state is obtained. Therefore, the SOC processing efficiency of the target battery during real-time running is improved by utilizing the relation among the charging/discharging current, the working temperature and the steady-state voltage under different SOCs stored in the steady-state equivalent circuit model database, and the real-time correction of the SOC is realized.
By executing the above steps, the SOC determining method based on the steady-state equivalent circuit model according to the embodiment of the present invention searches for the steady-state voltages under different SOCs corresponding to the current charging/discharging current and the current operating temperature of the target battery in the steady state by using the steady-state equivalent circuit model database storing the relationships between the charging/discharging current, the operating temperature and the steady-state voltage under different SOCs established based on the steady-state equivalent circuit model of the target battery, and determines the current SOC of the target battery by comparing the current steady-state voltage with the steady-state voltages under different SOCs. Therefore, the SOC can be effectively corrected in the running process of the real vehicle, and the whole scheme is small in calculation amount, high in precision and easy to implement.
An embodiment of the present invention further provides an SOC determining apparatus based on the steady-state equivalent circuit model, as shown in fig. 3, the SOC determining apparatus based on the steady-state equivalent circuit model includes:
the obtaining module 101 is configured to obtain a current charging/discharging current, a current steady-state voltage, and a current working temperature corresponding to a target battery in a steady state during an operation process of a target vehicle. For details, refer to the related description of step S101 in the above method embodiment, and no further description is provided here.
The first processing module 102 is configured to determine corresponding steady-state voltages under different SOCs from a steady-state equivalent circuit model database corresponding to the target battery based on the current charging/discharging current and the current working temperature, where the steady-state equivalent circuit model database stores relationships between the charging/discharging current, the working temperature, and the steady-state voltages under different SOCs, which are established based on a steady-state equivalent circuit model of the target battery. For details, refer to the related description of step S103 in the above method embodiment, and no further description is provided here.
The second processing module 103 is configured to determine the current SOC of the target battery based on a relationship between the current steady-state voltage and corresponding steady-state voltages in different SOCs. For details, refer to the related description of step S103 in the above method embodiment, and no further description is provided here.
Through the cooperative cooperation of the above components, the SOC determination apparatus based on the steady-state equivalent circuit model according to the embodiment of the present invention finds the steady-state voltages under different SOCs corresponding to the current charging/discharging current and the current operating temperature at the steady state of the target battery by using the steady-state equivalent circuit model database storing the relationships between the charging/discharging current, the operating temperature and the steady-state voltage under different SOCs established based on the steady-state equivalent circuit model of the target battery, and determines the current SOC of the target battery by comparing the current steady-state voltage with the steady-state voltages under different SOCs. Therefore, the SOC can be effectively corrected in the running process of the real vehicle, and the whole scheme is small in calculation amount, high in precision and easy to implement.
Further functional descriptions of the modules are the same as those of the corresponding method embodiments, and are not repeated herein.
There is also provided an electronic device according to an embodiment of the present invention, as shown in fig. 4, the electronic device may include a processor 901 and a memory 902, where the processor 901 and the memory 902 may be connected by a bus 903 or in another manner, and fig. 4 takes the example of being connected by the bus 903 as an example.
The memory 902, which is a non-transitory computer readable storage medium, may be used for storing non-transitory software programs, non-transitory computer executable programs, and modules, such as program instructions/modules corresponding to the methods in the method embodiments of the present invention. The processor 901 executes various functional applications and data processing of the processor by executing non-transitory software programs, instructions and modules stored in the memory 902, that is, implements the methods in the above-described method embodiments.
The memory 902 may include a storage program area and a storage data area, wherein the storage program area may store an application program required for operating the device, at least one function; the storage data area may store data created by the processor 901, and the like. Further, the memory 902 may include high speed random access memory, and may also include non-transitory memory, such as at least one magnetic disk storage device, flash memory device, or other non-transitory solid state storage device. In some embodiments, the memory 902 may optionally include memory located remotely from the processor 901, which may be connected to the processor 901 via a network. Examples of such networks include, but are not limited to, the internet, intranets, local area networks, mobile communication networks, and combinations thereof.
One or more modules are stored in the memory 902, which when executed by the processor 901 performs the methods in the above-described method embodiments.
The specific details of the electronic device may be understood by referring to the corresponding related descriptions and effects in the above method embodiments, and are not described herein again.
It will be understood by those skilled in the art that all or part of the processes of the methods of the embodiments described above can be implemented by hardware related to instructions of a computer program, and the program can be stored in a computer readable storage medium, and when executed, can include the processes of the embodiments of the methods described above. The storage medium may be a magnetic Disk, an optical Disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a Flash Memory (Flash Memory), a Hard Disk (Hard Disk Drive, abbreviated as HDD) or a Solid State Drive (SSD), etc.; the storage medium may also comprise a combination of memories of the kind described above.
Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations fall within the scope defined by the appended claims.
Claims (9)
1. A SOC determination method based on a steady-state equivalent circuit model is characterized by comprising the following steps:
acquiring current charging/discharging current, current steady-state voltage and current working temperature corresponding to a target battery in a steady state in the running process of a target vehicle;
determining corresponding steady-state voltages under different SOCs from a steady-state equivalent circuit model database corresponding to the target battery based on the current charging/discharging current and the current working temperature, wherein the steady-state equivalent circuit model database stores the relationships between the charging/discharging current, the working temperature and the steady-state voltages under different SOCs established based on a steady-state equivalent circuit model of the target battery, the steady-state equivalent circuit model is established according to the battery characteristics of the target battery, and the steady-state equivalent circuit model is expressed by the following formula:
Ut = EMF + IR，
wherein Ut represents terminal voltage, EMF represents electromotive force, R represents internal resistance, and I represents current, wherein EMF and R are influenced by temperature, SOC and current;
determining the current SOC of the target battery based on the relationship between the current steady-state voltage and the corresponding steady-state voltages under different SOCs;
acquiring a steady-state equivalent circuit model corresponding to the target battery;
based on the working parameter conditions of the target battery, performing charge and discharge tests on the steady-state equivalent circuit model under different SOC to obtain corresponding charge/discharge voltage, wherein the working parameter conditions comprise: working temperature range, charge/discharge current range;
calculating to obtain charging/discharging internal resistances and charging/discharging electromotive forces corresponding to different working parameter conditions based on corresponding charging/discharging voltages under different working parameter conditions;
calculating corresponding charging/discharging steady-state voltage based on charging/discharging internal resistance and charging/discharging electromotive force corresponding to different working parameter conditions under different SOC;
and constructing the steady-state equivalent circuit model database based on the corresponding relation between different working parameter conditions and charging/discharging steady-state voltages under different SOCs.
2. The method of claim 1, wherein determining the current SOC of the target battery based on the relationship of the current steady-state voltage to corresponding steady-state voltages at different SOCs comprises:
acquiring a first steady-state voltage closest to the current steady-state voltage from corresponding steady-state voltages under different SOC;
and determining the SOC corresponding to the first steady-state voltage as the current SOC of the target battery.
3. The method of claim 2, wherein prior to obtaining a present charge/discharge current, a present steady-state voltage, and a present operating temperature corresponding to a target battery at steady-state during operation of the target vehicle, the method further comprises:
collecting the charging/discharging current of the target battery according to a preset period when the target battery is in a working state;
acquiring the maximum charge/discharge current, the minimum charge/discharge current and the average charge/discharge current of the target battery in the current preset period;
judging whether the relationship among the maximum charge/discharge current, the minimum charge/discharge current and the average charge/discharge current meets the steady-state working relationship of the battery or not;
and when the relationship among the maximum charge/discharge current, the minimum charge/discharge current and the average charge/discharge current meets the steady-state working relationship of the battery, determining that the target battery is in a steady state.
4. The method of claim 3, further comprising:
determining the working state of the target battery based on the charging/discharging current of the target battery in the current preset period, wherein the working state comprises the following steps: a charged state and a discharged state.
5. The method of claim 4, wherein the obtaining a first steady-state voltage closest to the current steady-state voltage from corresponding steady-state voltages at different SOCs comprises:
and acquiring a first steady-state voltage which is the same as and closest to the current steady-state voltage in working state from corresponding steady-state voltages under different SOC based on the working state of the target battery.
6. The method of claim 2, wherein the calculating of the charging/discharging internal resistance and the charging/discharging electromotive force corresponding to different operating parameter conditions based on the charging/discharging voltages corresponding to different operating parameter conditions comprises:
acquiring charging/discharging voltage corresponding to the first charging/discharging current and the second charging/discharging current at the current temperature;
calculating the mean value of the charging/discharging currents of the first charging/discharging current and the second charging/discharging current, and determining the current charging/discharging current;
and calculating the current charging/discharging internal resistance and the charging/discharging electromotive force corresponding to the current charging/discharging current at the current temperature based on the charging/discharging voltage corresponding to the first charging/discharging current and the second charging/discharging current.
7. An apparatus for determining an SOC based on a steady-state equivalent circuit model, comprising:
the acquisition module is used for acquiring the current charging/discharging current, the current steady-state voltage and the current working temperature corresponding to the target battery in a steady state in the running process of the target vehicle;
a first processing module, configured to determine, based on the current charging/discharging current and the current operating temperature, corresponding steady-state voltages under different SOCs from a steady-state equivalent circuit model database corresponding to the target battery, where the steady-state equivalent circuit model database stores relationships between the charging/discharging current, the operating temperature, and the steady-state voltages under different SOCs that are established based on a steady-state equivalent circuit model of the target battery, the steady-state equivalent circuit model is established according to battery characteristics of the target battery, and the steady-state equivalent circuit model is expressed by the following formula:
Ut = EMF + IR，
wherein Ut represents terminal voltage, EMF represents electromotive force, R represents internal resistance, and I represents current, wherein EMF and R are influenced by temperature, SOC and current;
the second processing module is used for determining the current SOC of the target battery based on the relation between the current steady-state voltage and the corresponding steady-state voltages under different SOCs;
acquiring a steady-state equivalent circuit model corresponding to the target battery;
based on the working parameter conditions of the target battery, performing charge and discharge tests on the steady-state equivalent circuit model under different SOC to obtain corresponding charge/discharge voltage, wherein the working parameter conditions comprise: working temperature range, charge/discharge current range;
calculating to obtain charging/discharging internal resistances and charging/discharging electromotive forces corresponding to different working parameter conditions based on corresponding charging/discharging voltages under different working parameter conditions;
calculating corresponding charging/discharging steady-state voltage based on charging/discharging internal resistance and charging/discharging electromotive force corresponding to different working parameter conditions under different SOC;
and constructing the steady-state equivalent circuit model database based on the corresponding relation between different working parameter conditions and charging/discharging steady-state voltages under different SOCs.
8. An electronic device, comprising:
a memory and a processor, the memory and the processor being communicatively coupled to each other, the memory having stored therein computer instructions, the processor performing the method of any of claims 1-6 by executing the computer instructions.
9. A computer-readable storage medium having stored thereon computer instructions for causing a computer to perform the method of any one of claims 1-6.
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