CN110927592A - Method and device for estimating peak power of battery - Google Patents

Method and device for estimating peak power of battery Download PDF

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CN110927592A
CN110927592A CN201811018095.4A CN201811018095A CN110927592A CN 110927592 A CN110927592 A CN 110927592A CN 201811018095 A CN201811018095 A CN 201811018095A CN 110927592 A CN110927592 A CN 110927592A
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battery
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determining
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charge
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CN110927592B (en
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蔡伟
杨瑞
秦学
熊瑞
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Huawei Technologies Co Ltd
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    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R21/00—Arrangements for measuring electric power or power factor
    • 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]
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Abstract

The application discloses a method and a device for estimating peak power of a battery, which are used for avoiding the phenomenon of battery over-temperature caused by overlarge peak current estimation and improving the safety performance of the battery. The method comprises the following steps: acquiring the voltage of a battery to be tested at the current moment, the current of the battery to be tested at the current moment, the state of charge of the battery to be tested at the current moment and the temperature of the battery to be tested at the current moment; determining a first continuous peak current according to the constraint condition of the working temperature of the battery and the temperature at the current moment; determining a current to be subjected to a second continuous peak value according to the terminal voltage constraint condition and the voltage at the current moment; determining a third continuous peak current according to the constraint condition of the state of charge of the battery and the state of charge at the current moment; determining a minimum sustained peak current from the first sustained peak current, the second sustained peak current, and the third sustained peak current; determining a peak voltage from the minimum sustained peak current; and determining the peak power of the battery to be tested according to the minimum continuous peak current and the peak voltage.

Description

Method and device for estimating peak power of battery
Technical Field
The present disclosure relates to the field of batteries, and in particular, to a method and an apparatus for estimating a peak power of a battery.
Background
The peak power of the power battery is the maximum continuous power allowed to be discharged or charged by the power battery in a short time (usually 10s, 60s and the like), wherein the peak power of the battery comprises two types of charging peak power and discharging peak power.
In the existing scheme, on one hand, a battery equivalent circuit model is established, and a peak current estimation value based on voltage constraint is calculated based on a terminal voltage constraint condition of the model; on the other hand, a peak current estimation value based on the SOC constraint is calculated based on a battery state of charge (SOC) constraint condition. And taking the minimum value of the peak current estimated value based on the two constraint conditions to obtain a final peak current estimated value, substituting the value into a battery model state equation to obtain a corresponding voltage value, and multiplying the peak current by the corresponding voltage to obtain a final peak power estimated value.
In the existing scheme, the limitation of the working temperature of the battery is not considered, so that the prediction result is probably larger, the battery is subjected to an over-temperature phenomenon in the operation process, and the safety performance of the battery is influenced.
Disclosure of Invention
The embodiment of the application provides a method and a device for estimating the peak power of a battery, which are used for considering the influence of working temperature in the process of estimating the peak power of the battery, avoiding the phenomenon that the peak current is estimated too much to generate the over-temperature of the battery and improving the safety performance of the battery.
The first aspect of the present application provides a method for estimating a peak power of a battery, including: acquiring the voltage of a battery to be tested at the current moment, the current of the battery to be tested at the current moment, the state of charge of the battery to be tested at the current moment and the temperature of the battery to be tested at the current moment; measuring the continuous peak current of the battery to be tested under different constraint conditions, and firstly determining the first continuous peak current of the battery to be tested in a period of time according to the constraint conditions of the working temperature of the battery and the temperature at the current moment; secondly, determining a second continuous peak current of the battery to be tested in a period of time according to the terminal voltage constraint condition and the voltage at the current moment; then determining a third continuous peak current of the battery to be tested in a period of time according to the constraint condition of the state of charge of the battery and the state of charge at the current moment; comparing the magnitudes of the first continuous peak current, the second continuous peak current and the third continuous peak current and determining a minimum continuous peak current; determining the peak voltage of the battery to be tested in a period of time according to the minimum continuous peak current; and determining the peak power of the battery to be tested in a time interval according to the minimum continuous peak current and the peak voltage. In the embodiment of the application, the influence of the constraint condition of the working temperature of the battery on the peak current is considered while the constraint condition of the state of charge and the constraint condition of the terminal voltage are considered, so that the phenomenon that the peak current is estimated too much to generate the over-temperature of the battery is avoided. The safety performance of the battery is improved.
In one possible design, in a first implementation manner of the first aspect of the embodiment of the present application, the determining, according to the battery operating temperature constraint and the temperature at the present moment, a first continuous peak current of the battery to be tested in a time interval includes: acquiring the upper limit of the working temperature of the battery; determining the maximum allowable temperature rise of the battery according to the upper limit of the working temperature of the battery and the temperature at the current moment; and determining a first calculation formula according to a preset battery equivalent circuit model and the maximum allowable temperature rise of the battery, and obtaining a first continuous peak current. In the implementation mode, the maximum temperature rise allowed by the battery is determined according to the upper limit of the working temperature of the battery, the change temperature of the battery is ensured not to exceed the maximum temperature rise allowed by the battery, and the safety performance of the battery is improved.
In one possible design, in a second implementation manner of the first aspect of the embodiment of the present application, the determining a first calculation formula according to a preset battery equivalent circuit model and a maximum allowable temperature rise of the battery, and obtaining the first continuous peak current includes: establishing a thermal model of the battery according to a preset battery equivalent circuit model and the maximum allowable temperature rise of the battery, and obtaining a first equivalent formula:
Figure BDA0001785925970000021
wherein the content of the first and second substances,i is the equivalent current, R0Is ohmic internal resistance, R1For polarizing internal resistance, T is time, TambIs ambient temperature, TcellThe battery temperature, h is the battery heat exchange coefficient, A is the heat exchange area, m is the battery mass, and c is the battery specific heat capacity; determining a first calculation formula according to the first equivalent formula:
Figure BDA0001785925970000022
wherein the content of the first and second substances,
Figure BDA0001785925970000023
is the peak current, R0(T0) Is a temperature T0Ohmic internal resistance of time, R1(T0) Is a temperature T0Internal resistance to polarization of time, R0(Tmax) Is a temperature TmaxOhmic internal resistance of time, R1(Tmax) Is a temperature TmaxInternal polarization resistance of time, n being TcTotal number of samples in time, Δ T being unit sampling time, TambIs ambient temperature, T0The initial battery temperature, h the battery heat exchange coefficient, A the heat exchange area, m the battery mass, c the battery specific heat capacity, and Δ TmaxMaximum allowable temperature rise, T, for the batterymaxIs the upper limit of the battery operating temperature; and obtaining a first continuous peak current according to a first calculation formula. In the implementation mode, the calculation process of the first continuous peak current is refined, the first continuous peak current is calculated in the range of the upper limit of the working temperature of the battery, and the accuracy of the obtained first continuous peak current is improved.
In one possible design, in a third implementation manner of the first aspect of the embodiment of the present application, the determining, according to the terminal voltage constraint and the voltage at the present time, a second continuous peak current of the battery under test over a period of time includes: acquiring a terminal voltage constraint condition, wherein the terminal voltage constraint condition comprises an upper limit value of a terminal voltage, a lower limit value of the terminal voltage, a first time scale and a second time scale, the first time scale and the second time scale are used for controlling sampling duration, and the first time scale is larger than the second time scale; determining a second calculation formula according to a preset battery equivalent circuit model and terminal voltage constraint conditions, and obtaining a first estimated current; determining a third calculation formula according to a preset thermal model of the battery and a terminal voltage constraint condition, and obtaining a second estimated current; determining a first difference value between the first estimated current and the second estimated current; and if the first difference is smaller than the first threshold, determining the second estimated current as a second continuous peak current. In the implementation mode, a second calculation formula and a third calculation formula are determined according to terminal voltage constraint conditions of the battery, a first estimated current and a second estimated current are obtained respectively, a difference value between the first estimated current and the second estimated current is determined, when the difference value is smaller than a first threshold value, the second estimated current is used as a second continuous peak current, different time scales are adopted, and accuracy of calculation results is improved.
In one possible design, in a fourth implementation manner of the first aspect of the embodiment of the present application, when the discharge scenario is a discharge scenario, determining the second calculation formula according to a preset battery equivalent circuit model and a terminal voltage constraint condition, and obtaining the first estimated current includes: determining a second calculation formula according to a preset battery equivalent circuit model, a lower limit value of the terminal voltage, the first time scale and the second time scale:
Figure BDA0001785925970000024
wherein, TcFor a preset time interval, Ut,minIs the lower limit value of terminal voltage, OCV (z)0) Is the open circuit voltage of the battery, z0Is the state of charge of the battery, UD,kFor the cell polarization voltage, j is each sample time, Δ t is the unit sample duration, ηiFor the charge-discharge efficiency of the cell, C1Is the battery capacity, C1The unit of capacity of (A) is ampere second As, R1For polarizing internal resistance, R0Is ohmic internal resistance, tau is a time constant, Delta TLAt a first time scale, Δ TSIn the form of a second time scale, the time scale,
Figure BDA0001785925970000031
is the peak current, LlIs as followsThe number of samples taken on a time scale,
Figure BDA0001785925970000032
Lsis the number of samples of the second time scale,
Figure BDA0001785925970000033
and obtaining a first estimated current according to a second calculation formula. In the implementation mode, the calculation process of the first estimated current is refined, the first estimated current is calculated under the terminal voltage constraint condition, and the accuracy of the obtained first estimated current is improved.
In one possible design, in a fifth implementation manner of the first aspect of the embodiment of the present application, when the discharging scenario is a discharge scenario, the determining a third calculation formula according to a preset thermal model of the battery and a terminal voltage constraint condition, and the obtaining a second predicted current includes: determining a third calculation formula according to a preset thermal model of the battery, a lower limit value of the terminal voltage, the first time scale and the second time scale:
Figure BDA0001785925970000034
wherein, TcFor a preset time interval, Ut,minIs the lower limit value of terminal voltage, OCV (z)0) Is the open circuit voltage of the battery, z0Is the state of charge of the battery, UD,kFor the cell polarization voltage, j is each sample time, Δ t is the unit sample duration, ηiFor the charge-discharge efficiency of the cell, C1Is the battery capacity, C1The unit of capacity of (A) is ampere second As, T0Is the current temperature, T, of the batterymaxFor the duration T of the batterycMaximum temperature of the rear, TavgIs the average temperature over the duration of time,
Figure BDA0001785925970000035
R1(Tavg) For internal resistance to polarisation after temperature change, R0(Tavg) Is ohmic internal resistance after temperature change, tau is time constant, Delta TLAt a first time scale, Δ TSIs the second timeThe inter-scale dimension is a measure of,
Figure BDA0001785925970000036
is the peak current, LlIs the number of samples taken at a first time scale,
Figure BDA0001785925970000037
Lsis the number of samples of the second time scale,
Figure BDA0001785925970000038
and obtaining a second estimated current according to a third calculation formula. In the implementation mode, the calculation process of the second estimated current is refined, the second estimated current is calculated under the terminal voltage constraint condition, and the accuracy of the obtained second estimated current is improved.
In a possible design, in a sixth implementation manner of the first aspect of the embodiment of the present application, the method further includes: if the difference is larger than or equal to the first threshold, determining a new first estimated current; determining a new second estimated current; determining a second difference between the new first predicted current and the new second predicted current; if the second difference is smaller than the first threshold, determining the new second estimated current as a second continuous peak current; if the second difference is greater than or equal to the first threshold, recalculating the second calculation formula and the third calculation formula until the difference between the result of the second calculation formula and the result of the third calculation formula is less than the first threshold. In the implementation manner, a process of repeatedly calculating a second difference value of the new first estimated current and the new second estimated current is added until the second difference value is smaller than the first threshold value, and the new second estimated current is output as a second continuous peak current, so that the implementation manner of the embodiment of the application is added.
In one possible design, in a seventh implementation manner of the first aspect of the embodiment of the present application, the determining, according to the battery state of charge constraint and the state of charge at the present time, a third sustained peak current of the battery under test over a period of time includes: acquiring constraint conditions of the state of charge of the battery, wherein the constraint conditions of the state of charge of the battery comprise an upper limit value of the state of charge and a lower limit value of the state of charge; and obtaining a third continuous peak current according to the constraint condition of the state of charge of the battery, the state of charge at the current moment and a preset ampere-hour integral equation. In the implementation mode, the maximum temperature rise allowed by the battery is determined according to the upper limit of the working temperature of the battery, the change temperature of the battery is ensured not to exceed the maximum temperature rise allowed by the battery, and the safety performance of the battery is improved.
In one possible design, in an eighth implementation manner of the first aspect of the embodiment of the present application, when the discharge scenario is a discharge scenario, the obtaining a third continuous peak current according to the battery state of charge constraint condition, the state of charge at the current time, and a preset ampere-hour integral equation includes: determining a fourth calculation formula according to the lower limit value of the state of charge, the state of charge at the current moment and a preset ampere-hour integral equation:
Figure BDA0001785925970000041
wherein the content of the first and second substances,
Figure BDA0001785925970000042
is the peak current, CcapIs the battery capacity, CcapThe unit of capacity of (A) is ampere hour Ah, 3600 is unit conversion coefficient for converting hour into second, SOCminIs the lower limit of the state of charge, SOC is the state of charge at the present time, TcPeak power duration; and obtaining a third continuous peak current according to a fourth calculation formula. In the implementation mode, the calculation process of the third continuous peak current is refined, the third continuous peak current is calculated within the constraint range of the state of charge of the battery, and the accuracy of the obtained third continuous peak current is improved.
A second aspect of the present application provides an apparatus for estimating a peak power of a battery, including: the acquisition unit is used for acquiring the voltage of the battery to be tested at the current moment, the current of the battery to be tested at the current moment, the state of charge of the battery to be tested at the current moment and the temperature of the battery to be tested at the current moment; the first determining unit is used for determining a first continuous peak current of the battery to be tested in a period of time according to the battery working temperature constraint condition and the temperature at the current moment; the second determining unit is used for determining a second continuous peak current of the battery to be tested in a period of time according to the terminal voltage constraint condition and the voltage at the current moment; the third determining unit is used for determining a third continuous peak current of the battery to be tested within a period of time according to the battery charge state constraint condition and the charge state at the current moment; a fourth determination unit for determining a minimum sustained peak current from the first, second and third sustained peak currents; the fifth determining unit is used for determining the peak voltage of the battery to be tested in a period of time according to the minimum continuous peak current; and the sixth determining unit is used for determining the peak power of the battery to be tested in a time interval according to the minimum continuous peak current and the peak voltage. In the embodiment of the application, the influence of the constraint condition of the working temperature of the battery on the peak current is considered while the constraint condition of the state of charge and the constraint condition of the terminal voltage are considered, so that the phenomenon that the peak current is estimated too much to generate the over-temperature of the battery is avoided. The safety performance of the battery is improved.
In one possible design, in a first implementation manner of the second aspect of the embodiment of the present application, the first determining unit includes: the first acquisition module is used for acquiring the upper limit of the working temperature of the battery; the first determining module is used for determining the maximum temperature rise allowed by the battery according to the upper limit of the working temperature of the battery and the temperature at the current moment; and the second determining module is used for determining a first calculation formula according to a preset battery equivalent circuit model and the maximum allowable temperature rise of the battery and obtaining a first continuous peak current.
In a possible design, in a second implementation manner of the second aspect of the embodiment of the present application, the second determining module is specifically configured to: establishing a thermal model of the battery according to a preset battery equivalent circuit model and the maximum allowable temperature rise of the battery, and obtaining a first equivalent formula:
Figure BDA0001785925970000043
wherein I is equivalent current, R0Is ohmic internal resistance, R1For polarizing internal resistance, T is time, TambIs ambient temperature, TcellThe temperature of the battery, h is the heat exchange coefficient of the battery, A is the heat exchange area, and m isThe mass of the battery, c is the specific heat capacity of the battery; determining a first calculation formula according to the first equivalent formula:
Figure BDA0001785925970000044
wherein the content of the first and second substances,
Figure BDA0001785925970000051
is the peak current, R0(T0) Is a temperature T0Ohmic internal resistance of time, R1(T0) Is a temperature T0Internal resistance to polarization of time, R0(Tmax) Is a temperature TmaxOhmic internal resistance of time, R1(Tmax) Is a temperature TmaxInternal polarization resistance of time, n being TcTotal number of samples in time, Δ T being unit sampling time, TambIs ambient temperature, T0The initial battery temperature, h the battery heat exchange coefficient, A the heat exchange area, m the battery mass, c the battery specific heat capacity, and Δ TmaxMaximum allowable temperature rise, T, for the batterymaxIs the upper limit of the battery operating temperature; and obtaining a first continuous peak current according to a first calculation formula. In the implementation mode, the calculation process of the first continuous peak current is refined, the first continuous peak current is calculated in the range of the upper limit of the working temperature of the battery, and the accuracy of the obtained first continuous peak current is improved.
In a possible design, in a third implementation manner of the second aspect of the embodiment of the present application, the second determining unit includes: the second acquisition module is used for acquiring a terminal voltage constraint condition, wherein the terminal voltage constraint condition comprises an upper limit value of the terminal voltage, a lower limit value of the terminal voltage, a first time scale and a second time scale, the first time scale and the second time scale are used for controlling sampling duration, and the first time scale is larger than the second time scale; the third determining module is used for determining a second calculation formula according to a preset battery equivalent circuit model and terminal voltage constraint conditions and obtaining a first estimated current; the fourth determining module is used for determining a third calculation formula according to a preset thermal model of the battery and terminal voltage constraint conditions and obtaining a second estimated current; the fifth determining module is used for determining a first difference value of the first estimated current and the second estimated current; and the sixth determining module is used for determining the second estimated current as a second continuous peak current if the first difference is smaller than the first threshold. In the implementation mode, a second calculation formula and a third calculation formula are determined according to terminal voltage constraint conditions of the battery, a first estimated current and a second estimated current are obtained respectively, a difference value between the first estimated current and the second estimated current is determined, when the difference value is smaller than a first threshold value, the second estimated current is used as a second continuous peak current, different time scales are adopted, and accuracy of calculation results is improved.
In a possible design, in a fourth implementation manner of the second aspect of the embodiment of the present application, when the discharge scenario is a discharge scenario, the third determining module is specifically configured to: determining a second calculation formula according to a preset battery equivalent circuit model, a lower limit value of the terminal voltage, the first time scale and the second time scale:
Figure BDA0001785925970000052
wherein, TcFor a preset time interval, Ut,minIs the lower limit value of terminal voltage, OCV (z)0) Is the open circuit voltage of the battery, z0Is the state of charge of the battery, UD,kFor the cell polarization voltage, j is each sample time, Δ t is the unit sample duration, ηiFor the charge-discharge efficiency of the cell, C1Is the battery capacity, C1The unit of capacity of (A) is ampere second As, R1For polarizing internal resistance, R0Is ohmic internal resistance, tau is a time constant, Delta TLAt a first time scale, Δ TSIn the form of a second time scale, the time scale,
Figure BDA0001785925970000053
is the peak current, LlIs the number of samples taken at a first time scale,
Figure BDA0001785925970000054
Lsis the number of samples of the second time scale,
Figure BDA0001785925970000055
and obtaining a first estimated current according to a second calculation formula. In the implementation mode, the calculation process of the first estimated current is refined, the first estimated current is calculated under the terminal voltage constraint condition, and the accuracy of the obtained first estimated current is improved.
In a possible design, in a fifth implementation manner of the second aspect of the embodiment of the present application, when the discharge scenario is a discharge scenario, the fourth determining module is specifically configured to: determining a third calculation formula according to a preset thermal model of the battery, a lower limit value of the terminal voltage, the first time scale and the second time scale:
Figure BDA0001785925970000061
wherein, TcFor a preset time interval, Ut,minIs the lower limit value of terminal voltage, OCV (z)0) Is the open circuit voltage of the battery, z0Is the state of charge of the battery, UD,kFor the cell polarization voltage, j is each sample time, Δ t is the unit sample duration, ηiFor the charge-discharge efficiency of the cell, C1Is the battery capacity, C1The unit of capacity of (A) is ampere second As, T0Is the current temperature, T, of the batterymaxFor the duration T of the batterycMaximum temperature of the rear, TavgIs the average temperature over the duration of time,
Figure BDA0001785925970000062
R1(Tavg) For internal resistance to polarisation after temperature change, R0(Tavg) Is ohmic internal resistance after temperature change, tau is time constant, Delta TLAt a first time scale, Δ TSIn the form of a second time scale, the time scale,
Figure BDA0001785925970000063
is the peak current, LlIs the number of samples taken at a first time scale,
Figure BDA0001785925970000064
Lsis the number of samples of the second time scale,
Figure BDA0001785925970000065
and obtaining a second estimated current according to a third calculation formula. In the implementation mode, the calculation process of the second estimated current is refined, the second estimated current is calculated under the terminal voltage constraint condition, and the accuracy of the obtained second estimated current is improved.
In a possible design, in a sixth implementation manner of the second aspect of the embodiment of the present application, the second determining unit further includes: the third determining module is used for determining a new first estimated current if the difference value is larger than or equal to the first threshold value; the fourth determination module is used for determining a new second estimated current; a fifth determining module, configured to determine a second difference between the new second predicted current and the new third predicted current; a sixth determining module, configured to determine that the new second estimated current is a second continuous peak current if the second difference is smaller than the first threshold; and the calculating module is used for recalculating the second calculation formula and the third calculation formula if the second difference is greater than or equal to the first threshold until the difference between the result of the second calculation formula and the result of the third calculation formula is smaller than the first threshold. In the implementation manner, a process of repeatedly calculating a second difference value of the new first estimated current and the new second estimated current is added until the second difference value is smaller than the first threshold value, and the new second estimated current is output as a second continuous peak current, so that the implementation manner of the embodiment of the application is added.
In a possible design, in a seventh implementation manner of the second aspect of the embodiment of the present application, the third determining unit includes: the third acquisition module is used for acquiring constraint conditions of the state of charge of the battery, wherein the constraint conditions of the state of charge of the battery comprise an upper limit value and a lower limit value of the state of charge; and the seventh determining module is used for obtaining a third continuous peak current according to the constraint condition of the state of charge of the battery, the state of charge at the current moment and a preset ampere-hour integral equation. In the implementation mode, the maximum temperature rise allowed by the battery is determined according to the upper limit of the working temperature of the battery, the change temperature of the battery is ensured not to exceed the maximum temperature rise allowed by the battery, and the safety performance of the battery is improved.
In a possible design, in an eighth implementation manner of the second aspect of the embodiment of the present application, when the discharge scenario is a discharge scenario, the seventh determining module is specifically configured to: determining a fourth calculation formula according to the lower limit value of the state of charge, the state of charge at the current moment and a preset ampere-hour integral equation:
Figure BDA0001785925970000066
wherein the content of the first and second substances,
Figure BDA0001785925970000067
is the peak current, CcapIs the battery capacity, CcapThe unit of capacity of (A) is ampere hour Ah, 3600 is unit conversion coefficient for converting hour into second, SOCminIs the lower limit of the state of charge, SOC is the state of charge at the present time, TcPeak power duration; and obtaining a third continuous peak current according to a fourth calculation formula. In the implementation mode, the calculation process of the third continuous peak current is refined, the third continuous peak current is calculated within the constraint range of the state of charge of the battery, and the accuracy of the obtained third continuous peak current is improved.
A third aspect of the present application provides a terminal, comprising: a battery and a battery peak power estimation device; the estimation device of the battery peak power is the estimation device of the battery peak power in any implementation manner of the second aspect.
A fourth aspect of the present application provides a battery including the apparatus for estimating a peak power of the battery in any implementation manner of the second aspect.
A fifth aspect of the present application provides a computer-readable storage medium having stored therein instructions, which, when run on a computer, cause the computer to perform the method of the above-described aspects.
A sixth aspect of the present application provides a computer program product comprising instructions which, when run on a computer, cause the computer to perform the method of the above aspects.
According to the technical scheme, the embodiment of the application has the following advantages:
acquiring the voltage of a battery to be tested at the current moment, the current of the battery to be tested at the current moment, the state of charge of the battery to be tested at the current moment and the temperature of the battery to be tested at the current moment; measuring the continuous peak current of the battery to be tested under different constraint conditions, and firstly determining the first continuous peak current of the battery to be tested in a period of time according to the constraint conditions of the working temperature of the battery and the temperature at the current moment; secondly, determining a second continuous peak current of the battery to be tested in a period of time according to the terminal voltage constraint condition and the voltage at the current moment; then determining a third continuous peak current of the battery to be tested in a preset time interval according to the battery charge state constraint condition and the charge state at the current moment; comparing the magnitudes of the first continuous peak current, the second continuous peak current and the third continuous peak current and determining a minimum continuous peak current; determining the peak voltage of the battery to be tested in a period of time according to the minimum continuous peak current; and determining the peak power of the battery to be tested in a time interval according to the minimum continuous peak current and the peak voltage. In the embodiment of the application, the influence of the constraint condition of the working temperature of the battery on the peak current is considered while the constraint condition of the state of charge and the constraint condition of the terminal voltage are considered, so that the phenomenon that the peak current is estimated too much to generate the over-temperature of the battery is avoided. The safety performance of the battery is improved.
Drawings
FIG. 1 is a schematic diagram of an equivalent circuit model of a battery;
FIG. 2 is a schematic diagram of a whole vehicle system of the electric vehicle;
FIG. 3 is a schematic diagram of an embodiment of a method for estimating a peak power of a battery according to an embodiment of the present disclosure;
FIG. 4 is a schematic diagram of another embodiment of a method for estimating peak power of a battery according to an embodiment of the present application;
FIG. 5 is a schematic diagram of an embodiment of an apparatus for estimating peak power of a battery according to an embodiment of the present application;
FIG. 6 is a schematic diagram of another embodiment of an apparatus for estimating peak power of a battery according to an embodiment of the present application;
fig. 7 is a schematic structural diagram of a battery management system in an embodiment of the present application.
Detailed Description
The embodiment of the application provides a method and a device for estimating the peak power of a battery, which are used for considering the influence of working temperature in the process of estimating the peak power of the battery, avoiding the phenomenon that the peak current is estimated too much to generate the over-temperature of the battery and improving the safety performance of the battery.
In order to make the technical field better understand the scheme of the present application, the following description will be made on the embodiments of the present application with reference to the attached drawings.
References throughout this specification to "first" or "second", etc., are intended to distinguish between similar items and not necessarily to describe a particular order or sequence. Furthermore, references throughout this specification to "comprising" or "having" and any variations thereof are intended to cover non-exclusive inclusions, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
In the existing scheme, various estimation methods for battery peak power are provided, which specifically include: a peak power estimation method based on terminal voltage, a peak power estimation method based on state of charge (SOC), and a multi-constraint estimation method. Among them, the peak power estimation method based on terminal voltage is one of the most classical and common methods by establishing an equivalent circuit model of a battery, as shown in fig. 1. The battery consists of a voltage source (OCV), an ohmic internal resistance R and a polarized internal resistance R1Calculating the peak power of the battery according to the current state of the voltage source, the design limit value, the ohmic internal resistance of the battery and the polarization internal resistance of the battery; the peak power estimation method based on the SOC avoids unsafe charging and discharging operations when the SOC of the power battery is positioned at or close to a control limit value; multi-constraint estimation method combines battery self current and powerThe peak power over a period of time is estimated based on a model equation while taking into account the dynamic voltage characteristics of the battery, however, the method does not take into account the effect of temperature during the estimation process.
In order to solve the problems existing in the methods, the application provides a method and a device for estimating the peak power of the battery, and simultaneously considers the influence of terminal voltage, SOC and temperature on the peak power of the battery, so that the safety performance of the battery and the accuracy of the peak power of the battery are improved, and the calculation efficiency is improved.
The application of the present application is in a part of functions of a Battery Management System (BMS) of an electric vehicle, and a structure of a whole system of the electric vehicle is shown in fig. 2. The power battery system is used as a power source to provide enough energy and power for the whole vehicle so as to meet the driving range and dynamic requirements of the whole vehicle, and the BMS is used as a monitoring and management unit of the power battery pack and needs to ensure that the battery system is always in a safe and controllable state range. Each core component basically includes a power loop of a high-voltage loop and a communication loop of a Controller Area Network (CAN) loop, wherein the high-voltage loop takes a power battery system and a BMS as a core, and the CAN loop takes a Vehicle Control Unit (VCU) as a core, and the two realize a charging function of an on-board charger (OBC) and an off-board charger (OFC), a discharging function of a Motor (Motor) and an Air Conditioner (AC), and the like, so as to ensure normal use of the electric vehicle.
The application scenario is that the current battery peak power is estimated in real time in the using process of the power battery system of the electric automobile, and two working scenarios of discharging and feedback charging of the battery are covered. In a discharging scene, the discharging peak power is obtained through calculation, the value is provided for the VCU, and the VCU sets the maximum power which can be used by the current vehicle according to the value. The accuracy of the value can ensure the safety of the battery, avoid the over-temperature and over-discharge of the battery and maximize the power performance of the automobile. In a feedback charging scene, the charging peak power obtained through calculation is provided for the VCU, and the VCU sets the current maximum feedback charging power of the vehicle according to the value. The accuracy of the value can ensure the safety of the battery, avoid the over-temperature and over-charge of the battery, simultaneously can maximize the energy fed back by braking, and reduce the running cost.
For convenience of description, in the embodiments of the present application, a lithium battery is taken as an example for illustration, and the solution of the present application may also be applied to other types of batteries, including but not limited to lithium batteries, for example, lithium metal-air batteries, lead-acid batteries, nickel-hydrogen batteries, nickel-cadmium batteries, and the like, and is not limited herein.
For convenience of understanding, a specific flow of a discharging scenario in the embodiment of the present application is described below, and referring to fig. 3, an embodiment of the method for estimating a peak power of a battery in the embodiment of the present application includes:
301. and acquiring the voltage of the battery to be tested at the current moment, the current of the battery to be tested at the current moment, the state of charge of the battery to be tested at the current moment and the temperature of the battery to be tested at the current moment.
The estimation device of the battery peak power obtains the voltage of the battery to be measured at the current moment, the current of the battery to be measured at the current moment, the state of charge of the battery to be measured at the current moment and the temperature of the battery to be measured at the current moment in real time according to a period of time interval.
Specifically, the estimation device of the battery peak power acquires the voltage of the battery to be measured at the current moment, the current of the battery to be measured at the current moment, the state of charge of the battery to be measured at the current moment and the temperature of the battery to be measured at the current moment every 60 seconds. For example, the estimation device of the battery peak power counts time, starts from 0 second, and when the recorded time is 60 seconds, acquires the voltage of the battery to be measured at that time. Current, state of charge and temperature; when the recorded time is 120 seconds, the voltage of the battery to be tested at the moment is acquired again. Current, state of charge, and temperature.
It is understood that the duration of the time interval may be set according to practical situations, for example, the time interval may also be 30 seconds, 20 seconds, etc., and is not limited herein. The "time interval" is the duration of each estimated period determined according to actual needs. For example, if the estimated period (i.e., the estimated peak power of the battery over a period of time) is 30 seconds, then the estimated period is estimated every 30 seconds from the beginning of the timing, i.e., the interval is 30 seconds. The parameters of current, voltage and the like referred to in the embodiment of the present application are all parameters in the same time interval.
It should be noted that, a time interval referred to in the embodiments of the present application refers to the same time interval, that is, parameters referred to in the embodiments of the present application are all obtained or calculated in the same time period.
302. And determining a first continuous peak current of the battery to be tested in a period of time according to the battery working temperature constraint condition and the temperature at the current moment.
The estimation device of the battery peak power determines a first continuous peak current of the battery to be tested in a period of time according to the constraint condition of the battery working temperature and the temperature at the current moment.
Specifically, the upper limit of the working temperature of the battery is firstly obtained; secondly, determining the maximum allowable temperature rise of the battery according to the upper limit of the working temperature of the battery and the temperature at the current moment; and determining a first calculation formula according to the equivalent circuit model of the battery and the maximum allowable temperature rise of the battery, and obtaining a first continuous peak current.
For example, the upper limit T of the battery working temperature preset by the manufacturer is obtained firstmax(ii) a Then according to the obtained upper limit T of the working temperature of the batterymaxDetermining the maximum allowable temperature rise delta T of the battery according to the current temperature of the battery to be testedmax(ii) a According to a preset battery equivalent circuit model and the obtained maximum allowable temperature rise delta T of the batterymaxEstablishing a thermal model of the battery, and obtaining a first equivalent formula, namely formula (1):
Figure BDA0001785925970000091
wherein I is equivalent current, R0Is ohmic internal resistance, R1For polarizing internal resistance, T is time, TambIs ambient temperature, TcellThe battery temperature, h is the battery heat exchange coefficient, A is the heat exchange area, m is the battery mass, and c is the battery specific heat capacity; let the peak power duration TcThe internal ambient temperature is kept constant while taking into account the time from the initial moment to TcDuring the time, the battery temperature is from T0Increase to TmaxIn this paragraphThe internal resistance changes with temperature in time and cannot be regarded as a constant value. Derivable at the maximum temperature rise Δ TmaxThe peak current formula under the limiting condition, i.e., formula (2), is as follows:
Figure BDA0001785925970000092
Figure BDA0001785925970000093
is the peak current, R0(Ti)、R1(Ti) Respectively, the ith sampling time and the temperature TiOhmic and polarization internal resistances in time, n being TcTotal number of samples in time, Δ T being unit sampling time, TambIs ambient temperature, T0The initial battery temperature, h the battery heat exchange coefficient, A the heat exchange area, m the battery mass, c the battery specific heat capacity, and Δ TmaxAllowing a maximum temperature rise for the battery;
Figure BDA0001785925970000101
can be calculated by an optimization algorithm, but to realize embedded operation and reduce the operation complexity, we consider that at T0Increase to TmaxAnd the temperature changes linearly, the equation can be simplified to obtain a first calculation formula, namely formula (3):
Figure BDA0001785925970000102
R0(T0) Is a temperature T0Ohmic internal resistance of time, R1(T0) Is a temperature T0Internal resistance to polarization of time, R0(Tmax) Is a temperature TmaxOhmic internal resistance of time, R1(Tmax) Is a temperature TmaxPolarization internal resistance of time; and obtaining a first continuous peak current according to a first calculation formula.
303. And determining a second continuous peak current of the battery to be tested in a period of time according to the lower limit value of the terminal voltage and the voltage at the current moment.
And the estimation device of the battery peak power determines a second continuous peak current of the battery to be tested in a period of time according to the lower limit value of the terminal voltage and the voltage at the current moment.
Specifically, terminal voltage constraint conditions are obtained, wherein the terminal voltage constraint conditions comprise an upper limit value of a terminal voltage, a lower limit value of the terminal voltage, a first time scale and a second time scale, the first time scale and the second time scale are used for controlling sampling duration, and the first time scale is larger than the second time scale; determining a second calculation formula according to a preset battery equivalent circuit model and terminal voltage constraint conditions, and obtaining a first estimated current within a period of time interval; determining a third calculation formula according to a preset thermal model of the battery and terminal voltage constraint conditions, and obtaining a second estimated current within a period of time interval; determining a first difference value between the first estimated current and the second estimated current; and if the first difference is smaller than the first threshold, determining the second estimated current as a second continuous peak current.
It should be noted that, in the discharging scenario, only the lower limit value, the first time scale and the second time scale of the terminal voltage may be obtained, and in the feedback charging scenario, only the upper limit value, the first time scale and the second time scale of the terminal voltage may be obtained, or the upper limit value, the lower limit value, the first time scale and the second time scale of the terminal voltage may be obtained at the same time, which is not limited herein. In this embodiment, only the lower limit value, the first time scale, and the second time scale of the terminal voltage are obtained as an example for description.
For example, a terminal voltage constraint condition is obtained, and the terminal voltage constraint condition includes a lower limit value U of a terminal voltaget,minFirst time scale Δ TLAnd a second time scale Δ TSWherein, Δ TL>ΔTS(ii) a The battery current calculation formula at any time is obtained according to a preset battery equivalent circuit model, namely the formula (4):
Figure BDA0001785925970000103
wherein, UD,kIs the battery polarization voltage, Ut,k+1Is the battery terminal voltage, OCV (z)k) Is the open circuit voltage of the battery, zkAt is the state of charge of the battery, unit sample time, ηiFor the charge-discharge efficiency of the cell, C1Is the battery capacity, C1The unit of capacity of (A) is ampere second As, R1For polarizing internal resistance, R0Is ohmic internal resistance, tau is a time constant; the battery terminal voltage is greater than the lower voltage limit during discharge, U, taking into account the terminal voltage constraintst,k+1>Ut,minConverting the above calculation formula of battery current at any time into duration TcThe internal peak current estimation equation, equation (5), is as follows:
Figure BDA0001785925970000111
wherein, Ut,minIs the lower limit value of terminal voltage, OCV (z)0) Is the open circuit voltage of the battery, z0Is the state of charge of the battery, UD,kFor the cell polarization voltage, j is each sample time, Δ t is the unit sample duration, ηiFor the charge-discharge efficiency of the cell, C1Is the battery capacity, C1The unit of capacity of (A) is ampere second As, R1For polarizing internal resistance, R0Is ohmic internal resistance, tau is a time constant; the formula (5) includes a high-order power operation, and is difficult to operate in actual embedded processing, so that simplification is achieved. Because the time constant of the polarization voltage is large, the change is not large in the duration time of the peak current, the part contains L-1 power operation, the operation complexity is large, and therefore, a long time scale (a first time scale) Delta T is selectedLIs its sampling time. The inverse change of the open circuit voltage is relatively large, and the influence on the voltage is large, so that the short time scale (the second time scale) Delta T is selectedSUpdating equation (5) for its sampling time to obtain a second calculation equation, equation (6):
Figure BDA0001785925970000112
wherein, Ut,minIs the lower limit value of terminal voltage, OCV (z)0) Is the open circuit voltage of the battery, z0Is the state of charge of the battery, UD,kFor the cell polarization voltage, j is each sample time, Δ t is the unit sampleDuration, ηiFor the charge-discharge efficiency of the cell, C1Is the battery capacity, C1The unit of capacity of (A) is ampere second As, R1For polarizing internal resistance, R0Is ohmic internal resistance, tau is a time constant, Delta TLAt a first time scale, Δ TSIn the form of a second time scale, the time scale,
Figure BDA0001785925970000113
is the peak current, LlIs the number of samples taken at a first time scale,
Figure BDA0001785925970000114
Lsis the number of samples of the second time scale,
Figure BDA0001785925970000115
Tcis a preset time interval; calculating according to a second calculation formula to obtain a first estimated current; by the flow of electric current
Figure BDA0001785925970000116
For input, the calculation formula of the maximum temperature, namely formula (7), is obtained according to a preset thermal model of the battery:
Figure BDA0001785925970000117
wherein, TmaxFor the duration T of the batterycMaximum temperature of the latter, R1For polarizing internal resistance, R0Is ohmic internal resistance, h is the heat transfer coefficient of the battery, A is the heat transfer area, T0Is the current temperature, T, of the batteryambIs the ambient temperature, m is the battery mass, c is the battery specific heat capacity; set at duration TcThe temperature of the internal battery changes linearly, and the average temperature in the period is taken
Figure BDA0001785925970000118
Obtaining the ohmic internal resistance R of the battery after considering the temperature change according to a preset battery parameter table0(Tavg) And polarization internal resistance R1(Tavg) Taking these parameters as model parameters, a third calculation formula, namely formula (8), is obtained:
Figure BDA0001785925970000121
wherein, Ut,minIs the lower limit value of terminal voltage, OCV (z)0) Is the open circuit voltage of the battery, z0Is the state of charge of the battery, UD,kFor the cell polarization voltage, j is each sample time, Δ t is the unit sample duration, ηiFor the charge-discharge efficiency of the cell, C1Is the battery capacity, C1The unit of capacity of (A) is ampere second As, T0Is the current temperature, T, of the batterymaxFor the duration T of the batterycMaximum temperature of the rear, TavgIs the average temperature over the duration of time,
Figure BDA0001785925970000122
R1(Tavg) For internal resistance to polarisation after temperature change, R0(Tavg) Is ohmic internal resistance after temperature change, tau is time constant, Delta TLAt a first time scale, Δ TSIn the form of a second time scale, the time scale,
Figure BDA0001785925970000123
is the peak current, LlIs the number of samples taken at a first time scale,
Figure BDA0001785925970000124
Lsis the number of samples of the second time scale,
Figure BDA0001785925970000125
Tcis a preset time interval; calculating according to a third calculation formula to obtain a second estimated current; determining a first difference value between the first estimated current and the second estimated current; if the first difference is smaller than the first threshold, determining that the second estimated current is a second continuous peak current; if the first difference is greater than or equal to the first threshold, the second calculation formula (6)) and the third calculation formula (8)) are recalculated until a difference between a result of the second calculation formula (6)) and a result of the third calculation formula (8)) is less than the first threshold.
304. And determining a third continuous peak current of the battery to be tested in a period of time according to the lower limit value of the state of charge and the state of charge at the current moment.
And the estimation device of the battery peak power determines a third continuous peak current of the battery to be tested in a period of time according to the lower limit value of the state of charge and the state of charge at the current moment.
Specifically, a battery state of charge constraint condition is obtained, wherein the battery state of charge constraint condition comprises a lower limit value of a state of charge; and obtaining a third continuous peak current according to the constraint condition of the state of charge of the battery, the state of charge at the current moment and a preset ampere-hour integral equation.
For example, the constraint condition of the battery state of charge is obtained first, and the constraint condition of the battery state of charge includes a lower limit value SOC of the state of chargemin(ii) a Lower limit value SOC according to state of chargeminDetermining a fourth calculation formula, namely formula (9), by the state of charge (SOC) at the current moment and a preset ampere-hour integral equation:
Figure BDA0001785925970000126
wherein the content of the first and second substances,
Figure BDA0001785925970000127
is the peak current, CcapIs the battery capacity, CcapThe unit of capacity of (A) is ampere hour Ah, 3600 is unit conversion coefficient for converting hour into second, SOCminIs the lower limit of the state of charge, SOC is the state of charge at the present time, TcFor the duration of the peak power, the preset ampere-hour fraction equation is prior art and is not described herein again; obtaining a third continuous peak current according to a fourth calculation formula
Figure BDA0001785925970000128
It should be noted that, there is no specific sequence between step 302 and step 304, and the steps may be executed simultaneously, or may be executed sequentially according to the sequence of step 302, step 303, and step 304, or may be executed sequentially according to the sequence of step 303, step 302, and step 304, or may execute one or two of the steps first, which is not limited herein.
305. A minimum sustained peak current is determined from the first sustained peak current, the second sustained peak current, and the third sustained peak current.
The estimation device of the battery peak power determines the minimum continuous peak current according to the first continuous peak current, the second continuous peak current and the third continuous peak current.
Specifically, the magnitude of the first continuous peak current, the magnitude of the second continuous peak current and the magnitude of the third continuous peak current are sequentially compared, and a minimum current is selected as the minimum continuous peak current of the output.
306. And determining the peak voltage of the battery to be tested in a time interval according to the minimum continuous peak current.
And the estimation device of the battery peak power calculates the peak voltage of the battery to be measured in a time interval according to the determined minimum continuous peak current.
It should be noted that, in the case where the circuit is continuously constant, the peak voltage changes, and in the case of a discharge scene, the minimum value of the voltage is taken as the peak voltage in a certain time interval, and in the case of a feedback charge scene, the maximum value of the voltage is taken as the peak voltage in a certain time interval.
307. And determining the peak power of the battery to be tested in a time interval according to the minimum continuous peak current and the peak voltage.
The estimation device of the battery peak power determines the peak power of the battery to be tested in a time interval according to the minimum continuous peak current and the peak voltage. And multiplying the minimum continuous peak current by the peak voltage to obtain the peak power.
In the embodiment of the application, the influence of the constraint condition of the working temperature of the battery on the peak current is considered while the constraint condition of the state of charge and the constraint condition of the terminal voltage are considered, so that the phenomenon that the peak current is estimated too much to generate the over-temperature of the battery is avoided. The safety performance of the battery is improved. Meanwhile, the peak current estimation method under the terminal voltage constraint condition is improved, time scales with different sizes are adopted for prediction according to different time constants in the model, the calculation complexity is reduced, fluctuation of an estimation result is avoided, and the accuracy of the calculated continuous peak current is improved.
In order to facilitate understanding, a specific flow of the discharging scenario in the embodiment of the present application is described below, and referring to fig. 4, another embodiment of the method for estimating the peak power of the battery in the embodiment of the present application includes:
401. and acquiring the voltage of the battery to be tested at the current moment, the current of the battery to be tested at the current moment, the state of charge of the battery to be tested at the current moment and the temperature of the battery to be tested at the current moment.
402. And determining a first continuous peak current of the battery to be tested in a period of time according to the battery working temperature constraint condition and the temperature at the current moment.
Steps 401 to 402 are similar to steps 301 to 302, and are not described herein again.
403. And determining a second continuous peak current of the battery to be tested in a period of time according to the upper limit value of the terminal voltage and the voltage at the current moment.
And the estimation device of the battery peak power determines a second continuous peak current of the battery to be tested in a period of time according to the upper limit value of the terminal voltage and the voltage at the current moment.
Specifically, terminal voltage constraint conditions are obtained, wherein the terminal voltage constraint conditions comprise an upper limit value of terminal voltage, a first time scale and a second time scale, the first time scale and the second time scale are used for controlling sampling duration, and the first time scale is larger than the second time scale; determining a second calculation formula according to a preset battery equivalent circuit model and terminal voltage constraint conditions, and obtaining a first estimated current within a period of time interval; determining a third calculation formula according to a preset thermal model of the battery and terminal voltage constraint conditions, and obtaining a second estimated current within a period of time interval; determining a first difference value between the first estimated current and the second estimated current; and if the first difference is smaller than the first threshold, determining the second estimated current as a second continuous peak current.
It should be noted that, in the feedback charging scenario, only the upper limit value, the first time scale and the second time scale of the terminal voltage may be obtained, or the upper limit value, the lower limit value, the first time scale and the second time scale of the terminal voltage may be obtained at the same time, which is not limited herein. In this embodiment, only the upper limit value, the first time scale, and the second time scale of the terminal voltage are taken as an example for description.
For example, a terminal voltage constraint condition is obtained, and the terminal voltage constraint condition includes an upper limit value U of a terminal voltaget,maxFirst time scale Δ TLAnd a second time scale Δ TSWherein, Δ TL>ΔTS(ii) a The battery current calculation formula at any time is obtained according to a preset battery equivalent circuit model, namely the formula (10):
Figure BDA0001785925970000141
wherein, UD,kIs the battery polarization voltage, Ut,k+1Is the battery terminal voltage, OCV (z)k) Is the open circuit voltage of the battery, zkAt is the state of charge of the battery, unit sample time, ηiFor the charge-discharge efficiency of the cell, C1Is the battery capacity, C1The unit of capacity of (A) is ampere second As, R1For polarizing internal resistance, R0Is ohmic internal resistance, tau is a time constant; the battery terminal voltage is less than the upper voltage limit during charging, U, taking into account the terminal voltage constraintst,k+1<Ut,maxConverting the above calculation formula of battery current at any time into duration TcThe internal peak current estimation equation, equation (11), is as follows:
Figure BDA0001785925970000142
wherein, Ut,maxThe upper limit value of terminal voltage, OCV (z)0) Is the open circuit voltage of the battery, z0Is the state of charge of the battery, UD,kFor the cell polarization voltage, j is each sample time, Δ t is the unit sample duration, ηiAs a batteryCharge-discharge efficiency, C1Is the battery capacity, C1The unit of capacity of (A) is ampere second As, R1For polarizing internal resistance, R0Is ohmic internal resistance, tau is a time constant; the formula (11) includes a high-order operation, and is difficult to operate in actual embedded processing, so that simplification is achieved. Because the time constant of the polarization voltage is large, the change is not large in the duration time of the peak current, the part contains L-1 power operation, the operation complexity is large, and therefore, a long time scale (a first time scale) Delta T is selectedLIs its sampling time. The inverse change of the open circuit voltage is relatively large, and the influence on the voltage is large, so that the short time scale (the second time scale) Delta T is selectedSFor the sampling time, the formula (11) is updated with the above sampling time to obtain a second calculation formula, which is formula (12) in this embodiment:
Figure BDA0001785925970000143
wherein, Ut,maxThe upper limit value of terminal voltage, OCV (z)0) Is the open circuit voltage of the battery, z0Is the state of charge of the battery, UD,kFor the cell polarization voltage, j is each sample time, Δ t is the unit sample duration, ηiFor the charge-discharge efficiency of the cell, C1Is the battery capacity, C1The unit of capacity of (A) is ampere second As, R1For polarizing internal resistance, R0Is ohmic internal resistance, tau is a time constant, Delta TLAt a first time scale, Δ TSIn the form of a second time scale, the time scale,
Figure BDA0001785925970000151
is the peak current, LlIs the number of samples taken at a first time scale,
Figure BDA0001785925970000152
Lsis the number of samples of the second time scale,
Figure BDA0001785925970000153
Tcis a preset time interval; calculating according to a second calculation formula to obtain a first estimated current; by the flow of electric current
Figure BDA0001785925970000154
For input, the calculation formula of the maximum temperature, namely formula (7), is obtained according to a preset thermal model of the battery:
Figure BDA0001785925970000155
wherein, TmaxFor the duration T of the batterycMaximum temperature of the latter, R1For polarizing internal resistance, R0Is ohmic internal resistance, h is the heat transfer coefficient of the battery, A is the heat transfer area, T0Is the current temperature, T, of the batteryambIs the ambient temperature, m is the battery mass, c is the battery specific heat capacity; set at duration TcThe temperature of the internal battery changes linearly, and the average temperature in the period is taken
Figure BDA0001785925970000156
Obtaining the ohmic internal resistance R of the battery after considering the temperature change according to a preset battery parameter table0(Tavg) And polarization internal resistance R1(Tavg) Taking these parameters as model parameters, a third calculation formula is obtained, which is formula (13):
Figure BDA0001785925970000157
wherein, Ut,maxThe upper limit value of terminal voltage, OCV (z)0) Is the open circuit voltage of the battery, z0Is the state of charge of the battery, UD,kFor the cell polarization voltage, j is each sample time, Δ t is the unit sample duration, ηiFor the charge-discharge efficiency of the cell, C1Is the battery capacity, C1The unit of capacity of (A) is ampere second As, T0Is the current temperature, T, of the batterymaxFor the duration T of the batterycMaximum temperature of the rear, TavgIs the average temperature over the duration of time,
Figure BDA0001785925970000158
R1(Tavg) For internal resistance to polarisation after temperature change, R0(Tavg) The ohmic internal resistance after temperature change is shown as tau as a time constant,ΔTLAt a first time scale, Δ TSIn the form of a second time scale, the time scale,
Figure BDA0001785925970000159
is the peak current, LlIs the number of samples taken at a first time scale,
Figure BDA00017859259700001510
Lsis the number of samples of the second time scale,
Figure BDA00017859259700001511
Tcis a preset time interval; calculating according to a third calculation formula to obtain a second estimated current; determining a first difference value between the first estimated current and the second estimated current; if the first difference is smaller than the first threshold, determining that the second estimated current is a second continuous peak current; if the first difference is greater than or equal to the first threshold, the second calculation formula (12)) and the third calculation formula (13)) are recalculated until a difference between a result of the second calculation formula (12)) and a result of the third calculation formula (13)) is less than the first threshold.
404. And determining a third continuous peak current of the battery to be tested in a period of time according to the upper limit value of the state of charge and the state of charge at the current moment.
And the estimation device of the battery peak power determines a third continuous peak current of the battery to be tested in a period of time according to the upper limit value of the state of charge and the state of charge at the current moment.
Specifically, a battery state of charge constraint condition is obtained, wherein the battery state of charge constraint condition comprises an upper limit value of a state of charge; and obtaining a third continuous peak current according to the constraint condition of the state of charge of the battery, the state of charge at the current moment and a preset ampere-hour integral equation.
For example, the constraint condition of the battery state of charge is obtained first, and the constraint condition of the battery state of charge includes an upper limit value SOC of the state of chargemax(ii) a Upper limit SOC according to state of chargemaxDetermining a fourth calculation formula according to the SOC at the current moment and a preset ampere-hour integral equationThe examples are of formula (14):
Figure BDA0001785925970000161
wherein the content of the first and second substances,
Figure BDA0001785925970000162
is the peak current, CcapIs the battery capacity, CcapThe capacity unit of (A) is ampere hour Ah, 3600 is a conversion coefficient for converting hour into second, SOCmaxIs the upper limit value of the state of charge, SOC is the state of charge at the current moment, TcFor the duration of the peak power, the preset ampere-hour fraction equation is prior art and is not described herein again; obtaining a third continuous peak current according to a fourth calculation formula
Figure BDA0001785925970000163
It should be noted that there is no specific sequence between step 402 and step 404, and the steps may be executed simultaneously, or may be executed sequentially according to the sequence of step 402, step 403, and step 404, or may be executed sequentially according to the sequence of step 403, step 402, and step 404, or may be executed first one or two of the steps, which is not limited herein.
405. A minimum sustained peak current is determined from the first sustained peak current, the second sustained peak current, and the third sustained peak current.
406. And determining the peak voltage of the battery to be tested in a time interval according to the minimum continuous peak current.
407. And determining the peak power of the battery to be tested in a time interval according to the minimum continuous peak current and the peak voltage.
Steps 405 to 407 are similar to steps 305 to 307, and detailed description thereof is omitted.
In the embodiment of the application, the influence of the constraint condition of the working temperature of the battery on the peak current is considered while the constraint condition of the state of charge and the constraint condition of the terminal voltage are considered, so that the phenomenon that the peak current is estimated too much to generate the over-temperature of the battery is avoided. The safety performance of the battery is improved. Meanwhile, the peak current estimation method under the terminal voltage constraint condition is improved, time scales with different sizes are adopted for prediction according to different time constants in the model, the calculation complexity is reduced, fluctuation of an estimation result is avoided, and the accuracy of the calculated continuous peak current is improved.
With reference to fig. 5, the method for estimating the peak power of the battery in the embodiment of the present application is described above, and an embodiment of the apparatus 500 for estimating the peak power of the battery in the embodiment of the present application includes:
an obtaining unit 501, configured to obtain a voltage of a battery to be tested at a current moment, a current of the battery at the current moment, a state of charge of the battery at the current moment, and a temperature of the battery at the current moment;
a first determining unit 502, configured to determine a first continuous peak current of the battery to be tested in a time interval according to a battery operating temperature constraint condition and the temperature at the current time;
a second determining unit 503, configured to determine a second continuous peak current of the battery to be tested in the period of time according to the terminal voltage constraint condition and the voltage at the current time;
a third determining unit 504, configured to determine a third continuous peak current of the battery to be tested in the period of time according to a battery state of charge constraint condition and the state of charge at the current time;
a fourth determining unit 505, configured to determine a minimum sustained peak current according to the first sustained peak current, the second sustained peak current, and the third sustained peak current;
a fifth determining unit 506, configured to determine a peak voltage of the battery to be tested in the period of time according to the minimum continuous peak current;
a sixth determining unit 507, configured to determine a peak power of the battery to be tested in the period of time according to the minimum continuous peak current and the peak voltage.
In one possible implementation, the first determining unit 502 includes:
a first acquiring module 5021, configured to acquire an upper limit of a battery operating temperature;
a first determining module 5022, configured to determine the maximum temperature rise allowed by the battery according to the upper limit of the operating temperature of the battery and the temperature at the current time;
the second determining module 5023 is configured to determine a first calculation formula according to a preset battery equivalent circuit model and the maximum allowable temperature rise of the battery, and obtain a first continuous peak current.
In a possible implementation manner, the second determining module 5023 is specifically configured to:
establishing a battery thermal model according to a preset battery equivalent circuit model and the maximum allowable temperature rise of the battery, and obtaining a first equivalent formula:
Figure BDA0001785925970000171
wherein I is equivalent current, R0Is ohmic internal resistance, R1For polarizing internal resistance, T is time, TambIs ambient temperature, TcellThe battery temperature, h is the battery heat exchange coefficient, A is the heat exchange area, m is the battery mass, and c is the battery specific heat capacity;
determining a first calculation formula according to the first equivalent formula:
Figure BDA0001785925970000172
wherein the content of the first and second substances,
Figure BDA0001785925970000173
is the peak current, R0(T0) Is a temperature T0Ohmic internal resistance of time, R1(T0) Is a temperature T0Internal resistance to polarization of time, R0(Tmax) Is a temperature TmaxOhmic internal resistance of time, R1(Tmax) Is a temperature TmaxInternal polarization resistance of time, n being TcTotal number of samples in time, Δ T being unit sampling time, TambIs ambient temperature, T0The initial battery temperature, h the battery heat exchange coefficient, A the heat exchange area, m the battery mass, c the battery specific heat capacity, and Δ TmaxMaximum allowable temperature rise, T, for the batterymaxIs the upper limit of the battery operating temperature;
and obtaining a first continuous peak current according to the first calculation formula.
In one possible implementation manner, the second determining unit 503 includes:
a second obtaining module 5031, configured to obtain a terminal voltage constraint condition, where the terminal voltage constraint condition includes an upper limit of a terminal voltage, a lower limit of the terminal voltage, a first time scale and a second time scale, where the first time scale and the second time scale are used to control a sampling duration, and the first time scale is greater than the second time scale;
a third determining module 5032, configured to determine a second calculation formula according to a preset battery equivalent circuit model and the terminal voltage constraint condition, and obtain a first estimated current;
a fourth determining module 5033, configured to determine a third calculation formula according to a preset thermal model of the battery and the terminal voltage constraint condition, and obtain a second estimated current;
a fifth determining module 5034 configured to determine a first difference between the first predicted current and the second predicted current;
the sixth determining module 5035, if the first difference is smaller than the first threshold, is configured to determine that the second estimated current is the second continuous peak current.
In a possible implementation manner, the third determining module 5032 is specifically configured to:
determining a second calculation formula according to the preset battery equivalent circuit model, the lower limit value of the terminal voltage, the first time scale and the second time scale:
Figure BDA0001785925970000181
wherein, TcFor a preset time interval of time,Ut,minis the lower limit value of terminal voltage, OCV (z)0) Is the open circuit voltage of the battery, z0Is the state of charge of the battery, UD,kFor the cell polarization voltage, j is each sample time, Δ t is the unit sample duration, ηiFor the charge-discharge efficiency of the cell, C1Is the battery capacity, C1The unit of capacity of (A) is ampere second As, R1For polarizing internal resistance, R0Is ohmic internal resistance, tau is a time constant, Delta TLAt a first time scale, Δ TSIn the form of a second time scale, the time scale,
Figure BDA0001785925970000182
is the peak current, LlIs the number of samples taken at a first time scale,
Figure BDA0001785925970000183
Lsis the number of samples of the second time scale,
Figure BDA0001785925970000184
and obtaining a first estimated current according to the second calculation formula.
In a possible implementation manner, the fourth determining module 5033 is specifically configured to:
determining a third calculation formula according to the preset thermal model of the battery, the lower limit value of the terminal voltage, the first time scale and the second time scale:
Figure BDA0001785925970000185
wherein, TcFor a preset time interval, Ut,minIs the lower limit value of terminal voltage, OCV (z)0) Is the open circuit voltage of the battery, z0Is the state of charge of the battery, UD,kFor the cell polarization voltage, j is each sample time, Δ t is the unit sample duration, ηiFor the charge-discharge efficiency of the cell, C1Is the battery capacity, C1The unit of capacity of (A) is ampere second As, T0Is the current temperature, T, of the batterymaxFor the duration T of the batterycAfter thatMaximum temperature, TavgIs the average temperature over the duration of time,
Figure BDA0001785925970000186
R1(Tavg) For internal resistance to polarisation after temperature change, R0(Tavg) Is ohmic internal resistance after temperature change, tau is time constant, Delta TLAt a first time scale, Δ TSIn the form of a second time scale, the time scale,
Figure BDA0001785925970000187
is the peak current, LlIs the number of samples taken at a first time scale,
Figure BDA0001785925970000188
Lsis the number of samples of the second time scale,
Figure BDA0001785925970000189
and obtaining a second estimated current according to the third calculation formula.
In a possible implementation manner, the second determining unit 503 further includes:
the third determining module 5032, if the difference is greater than or equal to the first threshold, is configured to determine a new first estimated current;
the fourth determining module 5033, configured to determine a new second estimated current;
the fifth determining module 5034 configured to determine a second difference between the new second predicted current and the new third predicted current;
the sixth determining module 5035, if the second difference is smaller than the first threshold, is configured to determine that the new second estimated current is the second sustained peak current;
the calculating module 5036, if the second difference is greater than or equal to the first threshold, is configured to recalculate the second calculation formula and the third calculation formula until the difference between the result of the second calculation formula and the result of the third calculation formula is smaller than the first threshold.
In one possible implementation manner, the third determining unit 504 includes:
a third obtaining module 5041, configured to obtain constraint conditions of the state of charge of the battery, where the constraint conditions of the state of charge of the battery include an upper limit value of the state of charge and a lower limit value of the state of charge;
and the seventh determining module 5042 is configured to obtain a third continuous peak current according to the battery state of charge constraint condition, the state of charge at the current time, and a preset ampere-hour integral equation.
In a possible implementation manner, the seventh determining module 5042 is specifically configured to:
determining a fourth calculation formula according to the lower limit value of the state of charge, the state of charge at the current moment and a preset ampere-hour integral equation:
Figure BDA0001785925970000191
wherein the content of the first and second substances,
Figure BDA0001785925970000192
is the peak current, CcapIs the battery capacity, CcapThe unit of capacity of (A) is ampere hour Ah, 3600 is unit conversion coefficient for converting hour into second, SOCminIs the lower limit of the state of charge, SOC is the state of charge at the present time, TcPeak power duration;
and obtaining a third continuous peak current according to the fourth calculation formula.
Fig. 5 above describes in detail the estimation apparatus for peak power of battery in the embodiment of the present application from the perspective of the functional module, and the following describes in detail the estimation apparatus for peak power of battery in the embodiment of the present application from the perspective of hardware processing, please refer to fig. 6, where another embodiment of the estimation apparatus for peak power of battery in the embodiment of the present application includes:
fig. 6 is a schematic structural diagram of an apparatus for estimating a peak power of a battery 600 according to an embodiment of the present disclosure, which may generate a relatively large difference due to different configurations or performances, and may include one or more processors (CPUs) 601 (e.g., one or more processors) and a memory 609, and one or more storage media 608 (e.g., one or more mass storage devices) storing applications 607 or data 606. Memory 609 and storage media 608 may be, among other things, transient or persistent storage. The program stored on the storage medium 608 may include one or more modules (not shown), each of which may include a series of instruction operations in an apparatus for estimating peak power of a battery. Still further, the processor 601 may be configured to communicate with the storage medium 608 to execute a series of instruction operations in the storage medium 608 on the battery peak power estimation apparatus 600.
The device 600 for estimating the peak power of a battery may also include one or more power supplies 602, one or more wired or wireless network interfaces 603, one or more input-output interfaces 604, and/or one or more operating systems 605, such as Windows Server, Mac OS X, Unix, Linux, FreeBSD, etc. Those skilled in the art will appreciate that the configuration of the means for estimating the peak power of the battery shown in fig. 6 does not constitute a limitation of the means for estimating the peak power of the battery, and may include more or fewer components than those shown, or some components may be combined, or a different arrangement of components.
The following describes the components of the estimation device of the peak power of the battery in detail with reference to fig. 6:
the processor 601 is a control center of the estimation apparatus of the battery peak power, and may perform processing according to a set estimation method of the battery peak power. The processor 601 connects various parts of the entire battery peak power estimating apparatus using various interfaces and lines, performs various functions of the battery peak power estimating apparatus and processes data by running or executing software programs and/or modules stored in the memory 609, and calling up data stored in the memory 609, thereby estimating the battery peak power.
The memory 609 can be used for storing software programs and modules, and the processor 601 executes various functional applications and data processing of the estimation apparatus 600 for the peak power of the battery by running the software programs and modules stored in the memory 609. The memory 609 may mainly include a program storage area and a data storage area, where the program storage area may store an operating system, an application program required by at least one function (for example, obtaining a voltage of the battery to be tested at the current moment), and the like; the storage data area may store data created by use of the estimation device of the peak power of the battery (such as determining the peak voltage of the battery under test over a time interval, etc.), and the like. Further, the memory 609 may include high speed random access memory, and may also include non-volatile memory, such as at least one magnetic disk storage device, flash memory device, or other volatile solid state storage device. The program of the estimation method of the peak power of the battery provided in the embodiment of the present application and the received data stream are stored in the memory, and when needed to be used, the processor 601 calls from the memory 609.
The estimation apparatus of the peak power of the battery according to the embodiment of the present application may be a Battery Management System (BMS) 700, as shown in fig. 7, the BMS includes a state estimation module, a thermal management module, a charging and discharging management module, an information recording module, a battery equalization module, a data acquisition module, and a communication module, wherein the BMS is electrically connected to the power battery pack, the charging and discharging device/vehicle controller, and the estimation method of the peak power of the battery is embedded in the state estimation module of the BMS in the form of a core algorithm. The required data of this application are BMS's current data collection, and the hardware module also need not to increase any extra equipment for the current module of electric automobile.
The application also provides a terminal, which comprises a battery and a device for estimating the peak power of the battery;
the estimation device of the battery peak power is the estimation device of the battery peak power described in any of the above embodiments, and the structure of the estimation device of the battery peak power refers to the above embodiments, and details are not repeated here.
The present application further provides a battery, which includes any one of the above-mentioned estimation apparatuses for battery peak power in the above-mentioned embodiments, and the structure of the estimation apparatus for battery peak power refers to the above-mentioned embodiments, and details are not repeated here.
The computer program product includes one or more computer instructions. When loaded and executed on a computer, cause the processes or functions described in accordance with the embodiments of the application to occur, in whole or in part. The computer may be a general purpose computer, a special purpose computer, a network of computers, or other programmable device. The computer instructions may be stored on a computer readable storage medium or transmitted from one computer readable storage medium to another, for example, from one website, computer, server, or data center to another website, computer, server, or data center via wire (e.g., coaxial cable, fiber optic, Digital Subscriber Line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.). The computer-readable storage medium can be any available medium that a computer can store or a data storage device, such as a server, a data center, etc., that is integrated with one or more available media. The usable medium may be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium (e.g., Solid State Disk (SSD)), among others.
The integrated unit, if implemented in the form of a software functional unit and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present application may be substantially implemented or contributed to by the prior art, or all or part of the technical solution may be embodied in a software product, which is stored in a storage medium and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the method according to the embodiments of the present application. And the aforementioned storage medium includes: various media capable of storing program codes, such as a usb disk, a removable hard disk, a read-only memory (ROM), a Random Access Memory (RAM), a magnetic disk, or an optical disk.

Claims (22)

1. A method for estimating peak power of a battery, comprising:
acquiring the voltage of a battery to be tested at the current moment, the current of the battery to be tested at the current moment, the state of charge of the battery to be tested at the current moment and the temperature of the battery to be tested at the current moment;
determining a first continuous peak current of the battery to be tested in a period of time according to a battery working temperature constraint condition and the temperature at the current moment;
determining a second continuous peak current of the battery to be tested in the period of time according to the terminal voltage constraint condition and the voltage at the current moment;
determining a third continuous peak current of the battery to be tested in the period of time according to a battery charge state constraint condition and the charge state at the current moment;
determining a minimum sustained peak current from the first, second, and third sustained peak currents;
determining the peak voltage of the battery to be tested in the period of time according to the minimum continuous peak current;
and determining the peak power of the battery to be tested in the period of time according to the minimum continuous peak current and the peak voltage.
2. The estimation method according to claim 1, wherein the determining a first continuous peak current of the battery under test for a period of time according to the battery operating temperature constraint and the temperature at the present moment comprises:
acquiring the upper limit of the working temperature of the battery;
determining the maximum temperature rise allowed by the battery according to the upper limit of the working temperature of the battery and the temperature at the current moment;
and determining a first calculation formula according to a preset battery equivalent circuit model and the maximum allowable temperature rise of the battery, and obtaining a first continuous peak current.
3. The estimation method according to claim 2, wherein the determining a first calculation formula according to a preset battery equivalent circuit model and the maximum allowable temperature rise of the battery, and the obtaining a first continuous peak current comprises:
establishing a battery thermal model according to a preset battery equivalent circuit model and the maximum allowable temperature rise of the battery, and obtaining a first equivalent formula:
Figure FDA0001785925960000011
wherein I is equivalent current, R0Is ohmic internal resistance, R1For polarizing internal resistance, T is time, TambIs ambient temperature, TcellThe battery temperature, h is the battery heat exchange coefficient, A is the heat exchange area, m is the battery mass, and c is the battery specific heat capacity;
determining a first calculation formula according to the first equivalent formula:
Figure FDA0001785925960000012
wherein the content of the first and second substances,
Figure FDA0001785925960000013
is the peak current, R0(T0) Is a temperature T0Ohmic internal resistance of time, R1(T0) Is a temperature T0Internal resistance to polarization of time, R0(Tmax) Is a temperature TmaxOhmic internal resistance of time, R1(Tmax) Is a temperature TmaxInternal polarization resistance of time, n being TcTotal number of samples in time, Δ T being unit sampling time, TambIs ambient temperature, T0The initial battery temperature, h the battery heat exchange coefficient, A the heat exchange area, m the battery mass, c the battery specific heat capacity, and Δ TmaxMaximum allowable temperature rise, T, for the batterymaxIs the upper limit of the battery operating temperature;
and obtaining a first continuous peak current according to the first calculation formula.
4. The estimation method as claimed in claim 1, wherein said determining a second continuous peak current of the battery under test in the period of time according to the terminal voltage constraint and the voltage at the present moment comprises:
acquiring a terminal voltage constraint condition, wherein the terminal voltage constraint condition comprises an upper limit value of a terminal voltage, a lower limit value of the terminal voltage, a first time scale and a second time scale, the first time scale and the second time scale are used for controlling sampling time length, and the first time scale is larger than the second time scale;
determining a second calculation formula according to a preset battery equivalent circuit model and the terminal voltage constraint condition, and obtaining a first estimated current;
determining a third calculation formula according to a preset thermal model of the battery and the terminal voltage constraint condition, and obtaining a second estimated current;
determining a first difference between the first predicted current and the second predicted current;
and if the first difference is smaller than a first threshold value, determining that the second estimated current is the second continuous peak current.
5. The estimation method according to claim 4, wherein, in a discharging scenario, the determining a second calculation formula according to a preset battery equivalent circuit model and the terminal voltage constraint condition and obtaining a first estimated current comprises:
determining a second calculation formula according to the preset battery equivalent circuit model, the lower limit value of the terminal voltage, the first time scale and the second time scale:
Figure FDA0001785925960000021
wherein, TcFor a preset time interval, Ut,minIs a lower limit of terminal voltage，OCV(z0) Is the open circuit voltage of the battery, z0Is the state of charge of the battery, UD,kFor the cell polarization voltage, j is each sample time, Δ t is the unit sample duration, ηiFor the charge-discharge efficiency of the cell, C1Is the battery capacity, C1The unit of capacity of (A) is ampere second As, R1For polarizing internal resistance, R0Is ohmic internal resistance, tau is a time constant, Delta TLAt a first time scale, Δ TSIn the form of a second time scale, the time scale,
Figure FDA0001785925960000022
is the peak current, LlIs the number of samples taken at a first time scale,
Figure FDA0001785925960000023
Lsis the number of samples of the second time scale,
Figure FDA0001785925960000024
and obtaining a first estimated current according to the second calculation formula.
6. The estimation method of claim 5, wherein, in a discharging scenario, said determining a third calculation formula according to a preset thermal model of the battery and said terminal voltage constraint condition and obtaining a second estimated current comprises:
determining a third calculation formula according to the preset thermal model of the battery, the lower limit value of the terminal voltage, the first time scale and the second time scale:
Figure FDA0001785925960000025
wherein, TcFor a preset time interval, Ut,minIs the lower limit value of terminal voltage, OCV (z)0) Is the open circuit voltage of the battery, z0Is the state of charge of the battery, UD,kFor the cell polarization voltage, j is each sample time, Δ t is the unit sample duration, ηiFor the charge-discharge efficiency of the cell, C1Is the battery capacity, C1The unit of capacity of (A) is ampere second As, T0Is the current temperature, T, of the batterymaxFor the duration T of the batterycMaximum temperature of the rear, TavgIs the average temperature over the duration of time,
Figure FDA0001785925960000031
R1(Tavg) For internal resistance to polarisation after temperature change, R0(Tavg) Is ohmic internal resistance after temperature change, tau is time constant, Delta TLAt a first time scale, Δ TSIn the form of a second time scale, the time scale,
Figure FDA0001785925960000032
is the peak current, LlIs the number of samples taken at a first time scale,
Figure FDA0001785925960000033
Lsis the number of samples of the second time scale,
Figure FDA0001785925960000034
and obtaining a second estimated current according to the third calculation formula.
7. The estimation method according to any of claims 4-6, characterized in that the method further comprises:
if the difference is larger than or equal to the first threshold, determining a new first estimated current;
determining a new second estimated current;
determining a second difference between the new first predicted current and the new second predicted current;
if the second difference is smaller than the first threshold, determining the new second estimated current as the second continuous peak current;
if the second difference is greater than or equal to the first threshold, recalculating the second calculation formula and the third calculation formula until the difference between the result of the second calculation formula and the result of the third calculation formula is less than the first threshold.
8. The estimation method according to claim 1, wherein the determining a third continuous peak current of the battery under test in the period of time according to the battery state of charge constraint and the state of charge of the current time comprises:
acquiring constraint conditions of the state of charge of a battery, wherein the constraint conditions of the state of charge of the battery comprise an upper limit value of the state of charge and a lower limit value of the state of charge;
and obtaining a third continuous peak current according to the battery state of charge constraint condition, the state of charge at the current moment and a preset ampere-hour integral equation.
9. The estimation method according to claim 8, wherein, in a discharging scenario, said deriving a third continuous peak current according to the battery state-of-charge constraint, the state-of-charge at the current time, and a preset ampere-hour integral equation comprises:
determining a fourth calculation formula according to the lower limit value of the state of charge, the state of charge at the current moment and a preset ampere-hour integral equation:
Figure FDA0001785925960000035
wherein the content of the first and second substances,
Figure FDA0001785925960000036
is the peak current, CcapIs the battery capacity, CcapThe unit of capacity of (A) is ampere hour Ah, 3600 is unit conversion coefficient for converting hour into second, SOCminIs the lower limit of the state of charge, SOC is the state of charge at the present time, TcPeak power duration;
and obtaining a third continuous peak current according to the fourth calculation formula.
10. An apparatus for estimating a peak power of a battery, comprising:
the acquisition unit is used for acquiring the voltage of the battery to be tested at the current moment, the current of the battery to be tested at the current moment, the state of charge of the battery to be tested at the current moment and the temperature of the battery to be tested at the current moment;
the first determining unit is used for determining a first continuous peak current of the battery to be tested in a period of time according to a battery working temperature constraint condition and the temperature at the current moment;
the second determining unit is used for determining a second continuous peak current of the battery to be tested in the period of time according to the terminal voltage constraint condition and the voltage at the current moment;
the third determining unit is used for determining a third continuous peak current of the battery to be tested in the period of time according to a battery charge state constraint condition and the charge state at the current moment;
a fourth determination unit for determining a minimum sustained peak current from the first, second and third sustained peak currents;
a fifth determining unit, configured to determine a peak voltage of the battery to be tested in the period of time according to the minimum continuous peak current;
and the sixth determining unit is used for determining the peak power of the battery to be tested in the period of time according to the minimum continuous peak current and the peak voltage.
11. The estimation apparatus according to claim 10, wherein the first determination unit includes:
the first acquisition module is used for acquiring the upper limit of the working temperature of the battery;
the first determining module is used for determining the maximum temperature rise allowed by the battery according to the upper limit of the working temperature of the battery and the temperature at the current moment;
and the second determining module is used for determining a first calculation formula according to a preset battery equivalent circuit model and the maximum allowable temperature rise of the battery and obtaining a first continuous peak current.
12. The estimation apparatus according to claim 11, wherein the second determination module is specifically configured to:
establishing a battery thermal model according to a preset battery equivalent circuit model and the maximum allowable temperature rise of the battery, and obtaining a first equivalent formula:
Figure FDA0001785925960000041
wherein I is equivalent current, R0Is ohmic internal resistance, R1For polarizing internal resistance, T is time, TambIs ambient temperature, TcellThe battery temperature, h is the battery heat exchange coefficient, A is the heat exchange area, m is the battery mass, and c is the battery specific heat capacity;
determining a first calculation formula according to the first equivalent formula:
Figure FDA0001785925960000042
wherein the content of the first and second substances,
Figure FDA0001785925960000043
is the peak current, R0(T0) Is a temperature T0Ohmic internal resistance of time, R1(T0) Is a temperature T0Internal resistance to polarization of time, R0(Tmax) Is a temperature TmaxOhmic internal resistance of time, R1(Tmax) Is a temperature TmaxInternal polarization resistance of time, n being TcTotal number of samples in time, Δ T being unit sampling time, TambIs ambient temperature, T0The initial battery temperature, h the battery heat exchange coefficient, A the heat exchange area, m the battery mass, c the battery specific heat capacity, and Δ TmaxMaximum allowable temperature rise, T, for the batterymaxIs the upper limit of the battery operating temperature;
and obtaining a first continuous peak current according to the first calculation formula.
13. The estimation apparatus according to claim 10, wherein the second determination unit includes:
the terminal voltage constraint condition comprises an upper limit value of the terminal voltage, a lower limit value of the terminal voltage, a first time scale and a second time scale, the first time scale and the second time scale are used for controlling sampling duration, and the first time scale is larger than the second time scale;
the third determining module is used for determining a second calculation formula according to a preset battery equivalent circuit model and the terminal voltage constraint condition and obtaining a first estimated current;
the fourth determining module is used for determining a third calculation formula according to a preset battery thermal model and the terminal voltage constraint condition and obtaining a second estimated current;
a fifth determining module, configured to determine a first difference between the first predicted current and the second predicted current;
and a sixth determining module, configured to determine that the second estimated current is the second continuous peak current if the first difference is smaller than a first threshold.
14. The estimation apparatus according to claim 13, wherein, in the case of a discharging scenario, the third determination module is specifically configured to:
determining a second calculation formula according to the preset battery equivalent circuit model, the lower limit value of the terminal voltage, the first time scale and the second time scale:
Figure FDA0001785925960000051
wherein, TcFor a preset time interval, Ut,minIs the lower limit value of terminal voltage, OCV (z)0) Is the open circuit voltage of the battery, z0Is the state of charge of the battery, UD,kFor the cell polarization voltage, j is each sampling time, Δ t is unityBit sample duration, ηiFor the charge-discharge efficiency of the cell, C1Is the battery capacity, C1The unit of capacity of (A) is ampere second As, R1For polarizing internal resistance, R0Is ohmic internal resistance, tau is a time constant, Delta TLAt a first time scale, Δ TSIn the form of a second time scale, the time scale,
Figure FDA0001785925960000052
is the peak current, LlIs the number of samples taken at a first time scale,
Figure FDA0001785925960000053
Lsis the number of samples of the second time scale,
Figure FDA0001785925960000054
and obtaining a first estimated current according to the second calculation formula.
15. The estimation apparatus according to claim 14, wherein, in the case of a discharging scenario, the fourth determination module is specifically configured to:
determining a third calculation formula according to the preset thermal model of the battery, the lower limit value of the terminal voltage, the first time scale and the second time scale:
Figure FDA0001785925960000055
wherein, TcFor a preset time interval, Ut,minIs the lower limit value of terminal voltage, OCV (z)0) Is the open circuit voltage of the battery, z0Is the state of charge of the battery, UD,kFor the cell polarization voltage, j is each sample time, Δ t is the unit sample duration, ηiFor the charge-discharge efficiency of the cell, C1Is the battery capacity, C1The unit of capacity of (A) is ampere second As, T0Is the current temperature, T, of the batterymaxFor the duration T of the batterycMaximum temperature of the rear, TavgFor a duration of timeThe average temperature of (a) is,
Figure FDA0001785925960000061
R1(Tavg) For internal resistance to polarisation after temperature change, R0(Tavg) Is ohmic internal resistance after temperature change, tau is time constant, Delta TLAt a first time scale, Δ TSIn the form of a second time scale, the time scale,
Figure FDA0001785925960000062
is the peak current, LlIs the number of samples taken at a first time scale,
Figure FDA0001785925960000063
Lsis the number of samples of the second time scale,
Figure FDA0001785925960000064
and obtaining a second estimated current according to the third calculation formula.
16. The estimation apparatus according to any one of claims 13-15, characterized in that the second determination unit further comprises:
the third determining module is used for determining a new first estimated current if the difference is greater than or equal to the first threshold value
The fourth determination module is used for determining a new second estimated current;
the fifth determining module is configured to determine a second difference between the new second predicted current and the new third predicted current;
the sixth determining module is configured to determine that the new second estimated current is the second continuous peak current if the second difference is smaller than the first threshold;
and the calculating module is used for recalculating the second calculation formula and the third calculation formula if the second difference is greater than or equal to the first threshold until the difference between the result of the second calculation formula and the result of the third calculation formula is smaller than the first threshold.
17. The estimation device according to claim 10, characterized in that the third determination unit comprises:
the third acquisition module is used for acquiring constraint conditions of the state of charge of the battery, wherein the constraint conditions of the state of charge of the battery comprise an upper limit value and a lower limit value of the state of charge;
and the seventh determining module is used for obtaining a third continuous peak current according to the battery state of charge constraint condition, the state of charge at the current moment and a preset ampere-hour integral equation.
18. The estimation apparatus according to claim 17, wherein, in the case of a discharging scenario, the seventh determination module is specifically configured to:
determining a fourth calculation formula according to the lower limit value of the state of charge, the state of charge at the current moment and a preset ampere-hour integral equation:
Figure FDA0001785925960000065
wherein the content of the first and second substances,
Figure FDA0001785925960000066
is the peak current, CcapIs the battery capacity, CcapThe unit of capacity of (A) is ampere hour Ah, 3600 is unit conversion coefficient for converting hour into second, SOCminIs the lower limit of the state of charge, SOC is the state of charge at the present time, TcPeak power duration;
and obtaining a third continuous peak current according to the fourth calculation formula.
19. A terminal, comprising:
a battery and a battery peak power estimation device;
the estimation device of the peak power of the battery is the estimation device of the peak power of the battery according to any one of the claims 10 to 16.
20. A battery, characterized in that,
the battery comprises an estimation device of the peak power of the battery as claimed in any one of the preceding claims 10-16.
21. A computer-readable storage medium comprising instructions that, when executed on a computer, cause the computer to perform the method of any of claims 1-9.
22. A computer program product comprising instructions which, when run on a computer, cause the computer to perform the method of any one of claims 1-9.
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