CN115047353A - Method and device for predicting state of charge related parameters based on impedance decomposition - Google Patents

Method and device for predicting state of charge related parameters based on impedance decomposition Download PDF

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CN115047353A
CN115047353A CN202210975937.5A CN202210975937A CN115047353A CN 115047353 A CN115047353 A CN 115047353A CN 202210975937 A CN202210975937 A CN 202210975937A CN 115047353 A CN115047353 A CN 115047353A
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value
impedance value
impedance
battery
depth
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CN115047353B (en
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胡宇
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Nationz Technologies Inc
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/36—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
    • G01R31/367—Software therefor, e.g. for battery testing using modelling or look-up tables
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/36—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
    • G01R31/382—Arrangements for monitoring battery or accumulator variables, e.g. SoC
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/36—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
    • G01R31/389—Measuring internal impedance, internal conductance or related variables
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/4285—Testing apparatus
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/44—Methods for charging or discharging

Abstract

The embodiment of the application discloses a battery management system state of charge related parameter prediction method and a related device based on impedance decomposition, wherein the method comprises the following steps: obtaining a plurality of groups of target current values and a plurality of groups of target voltage values by adjusting the variable resistor for a plurality of times; calculating a first depth of discharge value, a first open-circuit voltage value and a first temperature value of the battery; and calculating a first impedance value, a second impedance value and a third impedance value of the battery through the known quantities to predict the charge state related parameters, wherein the first impedance value is the sum of the ohmic impedance value and the Faraday impedance value, the second impedance value is the electrochemical reaction impedance value, and the third impedance value is the concentration polarization impedance value.

Description

Method and device for predicting state of charge related parameters based on impedance decomposition
Technical Field
The embodiment of the application relates to the field of batteries, in particular to a method and a device for predicting state of charge related parameters based on impedance decomposition.
Background
In the current lithium ion battery management system state-of-charge related parameter prediction methods, in addition to the basic ampere-hour integration method, the battery chemical characteristic method, and other methods, a more accurate method is needed to correct the state-of-charge related parameters of the battery, such as relative state-of-charge (RSOC), for a large current or temperature change scene.
A more accurate prior art method is to predict the state of charge related parameters of the battery by updating the dc internal resistance in real time. However, the dc internal resistance in the conventional method is based on the ratio of two fixed voltage differences to the current difference at different temperatures and different depths of discharge of the battery, which is a simplified impedance model. Actually, when the battery is charged and discharged, there are internal electron or ion transfer in the micro world of the lithium ion battery, and the movement of lithium ion transfer, diffusion, solvation and desolvation of lithium ion in solid and liquid phases, as well as the transfer of lithium ion in solid electrode and electrolyte interface film (SEI Layer) are all concrete expressions. Besides solvation and desolvation, the other motions are relatively slow in speed and are speed control steps, and the motions are virtualized to be impedance, so that the impedance corresponds to ohmic impedance, Faraday impedance, electrochemical reaction impedance and concentration polarization impedance. The four impedances contribute to the respective polarization overvoltages according to different functional relationships, wherein the polarization overvoltages of the electrochemical reaction impedance and the concentration polarization impedance are not in a linear relationship with the corresponding currents, except that the polarization overvoltages of the ohmic impedance and the faraday impedance are in a linear relationship with the corresponding currents. Therefore, the direct current internal resistance obtained by a linear method is not accurate enough, so that the predicted polarization overvoltage is not accurate, the charge state related parameters are not accurate enough, and certain inconvenience is brought to users.
Disclosure of Invention
The embodiment of the application provides a method and a device for predicting state of charge related parameters based on impedance decomposition, so as to improve the prediction accuracy of the state of charge related parameters in a battery management system.
A battery management system state of charge related parameter prediction method based on impedance decomposition comprises the following steps:
when the discharging process of the battery meets a preset condition, obtaining multiple groups of target current values and multiple groups of target voltage values of the battery by adjusting the variable resistor for multiple times from a first time point to a second time point, wherein the adjusting time length of the variable resistor at each time is a preset time length corresponding to the adjustment;
calculating a first depth of discharge value and a first open-circuit voltage value of the battery at the second time point, and acquiring a first temperature value of the battery at the second time point;
calculating a first impedance value, a second impedance value and a third impedance value of the battery at the second time point according to the first depth of discharge value, the first open-circuit voltage value, the multiple groups of target current values, the multiple groups of target voltage values, the first temperature value and the multiple preset durations, wherein the first impedance value is the sum of an ohmic impedance value and a faradaic impedance value of the battery, the second impedance value is an electrochemical reaction impedance value of the battery, and the third impedance value is a concentration polarization impedance value of the battery;
predicting a target depth of discharge value corresponding to a cut-off voltage according to the first impedance value, the second impedance value and the third impedance value;
and obtaining the state of charge related parameters of the battery at the second time point according to the target depth of discharge value, wherein the state of charge related parameters comprise the full charge capacity, the residual capacity and the relative state of charge of the battery.
Optionally, predicting a target depth of discharge value corresponding to a cut-off voltage according to the first impedance value, the second impedance value, and the third impedance value includes:
calculating a fourth impedance value, a fifth impedance value, a sixth impedance value, a second depth of discharge value, a second open-circuit voltage value and a second temperature value according to the first impedance value, the second impedance value and the third impedance value, the second depth of discharge value is a set depth of discharge value, the second open-circuit voltage value is a voltage value corresponding to the second depth of discharge value, the second temperature value is a predicted temperature of a surface of the battery when the depth of discharge value of the battery is the second depth of discharge value, the fourth impedance value is a sum of an ohmic impedance value and a Faraday impedance value in the battery when the battery is at the second temperature value, the fifth impedance value is an impedance value of an electrochemical reaction in the battery when the battery is at the second temperature value, the sixth impedance value is a concentration polarization impedance value in the battery when the battery is at the second temperature value;
predicting a target depth of discharge value corresponding to a cut-off voltage according to target data, where the target data includes the target current value, the first depth of discharge value, the first open-circuit voltage value, the target voltage value, the first temperature value, the preset time duration, the fourth impedance value, the fifth impedance value, the sixth impedance value, the second depth of discharge value, the second open-circuit voltage value, and the second temperature value.
Optionally, the calculating, by using the first depth of discharge value, the first open-circuit voltage value, the multiple sets of target current values, the multiple sets of target voltage values, the first temperature value, and the multiple preset durations, a first impedance value, a second impedance value, and a third impedance value of the battery at the second time point includes:
calculating the first impedance value, the second impedance value and the third impedance value by the following formulas:
Figure DEST_PATH_IMAGE001
；
wherein the content of the first and second substances,
Figure 777094DEST_PATH_IMAGE002
in order to polarize the over-potential,
Figure DEST_PATH_IMAGE003
is the first open-circuit voltage value and,
Figure 921767DEST_PATH_IMAGE004
in order to be the value of the target voltage,
Figure DEST_PATH_IMAGE005
for the purpose of the target current value, the current value,
Figure 238479DEST_PATH_IMAGE006
for the purpose of the first value of the impedance,
Figure DEST_PATH_IMAGE007
for the first depth-of-discharge value,
Figure 101393DEST_PATH_IMAGE008
is the value of the first temperature, and is,
Figure DEST_PATH_IMAGE009
as a function of the impedance of the electrochemical reaction,
Figure 528963DEST_PATH_IMAGE010
for the value of the second impedance to be,
Figure DEST_PATH_IMAGE011
for the diffusion function followed by the third impedance value,
Figure 793722DEST_PATH_IMAGE012
the time is the preset time length,
Figure DEST_PATH_IMAGE013
is the third impedance value.
Optionally, when the discharging process of the battery meets a preset condition, the variable resistor is adjusted multiple times from a first time point to a second time point, where the preset condition is met, to obtain multiple groups of target current values and multiple groups of target voltage values of the battery, where the method includes:
when the discharge current increase value of the battery is larger than a preset threshold value, the variable resistor is adjusted for multiple times from the first time point meeting the preset condition to the second time point through multiple preset time lengths, and the multiple groups of target current values and the multiple groups of target voltage values of the battery are obtained;
or the like, or, alternatively,
and when the discharging current of the battery lasts for a preset time period, the variable resistor is adjusted for multiple times from the first time point meeting the preset condition to the second time point through multiple preset time periods, so that the multiple groups of target current values and the multiple groups of target voltage values of the battery are obtained.
Optionally, the calculating a fourth impedance value, a fifth impedance value, a sixth impedance value, a second depth of discharge value, a second open-circuit voltage value, and a second temperature value according to the first impedance value, the second impedance value, and the third impedance value includes:
obtaining a second depth of discharge value according to the first depth of discharge value and a segmentation depth of discharge value, wherein the segmentation depth of discharge value is a preset value;
and obtaining the second open-circuit voltage value, the second temperature value, the fourth impedance value, the fifth impedance value and the sixth impedance value according to the first impedance value, the second impedance value, the third impedance value, the second depth of discharge value and the preset calculation relationship among the open-circuit voltage, the depth of discharge and the temperature.
Optionally, after obtaining the second open-circuit voltage value, the second temperature value, the fourth impedance value, the fifth impedance value, and the sixth impedance value according to the first impedance value, the second impedance value, the third impedance value, the second depth of discharge value, and the preset calculation relationship among the open-circuit voltage, the depth of discharge, and the temperature, the method further includes:
adjusting the fourth impedance value, the fifth impedance value and the sixth impedance value according to a preset proportion;
respectively judging whether the adjusted fourth impedance value, the adjusted fifth impedance value and the adjusted sixth impedance value are valid data or not based on the preset relations among the impedances, the depth of discharge and the temperature;
if not, replacing the impedance value which does not belong to the effective data based on the preset relation among the impedances, the depth of discharge and the temperature to obtain a fourth impedance value, a fifth impedance value and a sixth impedance value which belong to the effective data.
Optionally, predicting a target depth of discharge value corresponding to the cut-off voltage according to the target data includes:
calculating according to the target data to obtain a predicted voltage, wherein the predicted voltage is the predicted voltage at two ends of the battery when the battery is connected with a load;
and determining the depth of discharge value corresponding to the maximum value smaller than or equal to the cut-off voltage in the predicted voltage as the target depth of discharge value.
A battery management system, comprising:
the device comprises an adjusting unit, a control unit and a control unit, wherein the adjusting unit is used for adjusting a variable resistor for multiple times from a first time point to a second time point when the discharging process of the battery meets a preset condition to obtain multiple groups of target current values and multiple groups of target voltage values of the battery, and the adjusting time length of the variable resistor at each time is a preset time length corresponding to the current adjustment;
the processing unit is used for calculating a first depth of discharge value and a first open-circuit voltage value of the battery at the second time point and acquiring a first temperature value of the battery at the second time point;
a calculating unit, configured to calculate, according to the first depth of discharge value, the first open-circuit voltage value, the multiple sets of target current values, the multiple sets of target voltage values, the first temperature value, and the multiple preset durations, a first impedance value, a second impedance value, and a third impedance value of the battery at the second time point, where the first impedance value is a sum of an ohmic impedance value and a faraday impedance value of the battery, the second impedance value is an electrochemical reaction impedance value of the battery, and the third impedance value is a concentration polarization impedance value of the battery;
the prediction unit is used for predicting a target depth of discharge value corresponding to a cut-off voltage according to the first impedance value, the second impedance value and the third impedance value;
the processing unit is further configured to obtain state of charge related parameters of the battery at the second time point according to the target depth of discharge value, where the state of charge related parameters include full charge capacity, residual capacity, and relative state of charge of the battery.
A battery management system, comprising:
the system comprises a central processing unit, a memory and an input/output interface;
the memory is a transient memory or a persistent memory;
the central processor is configured to communicate with the memory and execute the instruction operations in the memory to perform the aforementioned methods.
A computer-readable storage medium comprising instructions which, when executed on a computer, cause the computer to perform the aforementioned method.
According to the technical scheme, the embodiment of the application has the following advantages:
and after the preset conditions are met, the variable resistor is adjusted to obtain at least three groups of target current values and at least three groups of target voltage values, then a first depth of discharge value and a first open-circuit voltage value are calculated, and a first temperature value is obtained. And then calculating according to the obtained known quantity to obtain a first impedance value, a second impedance value and a third impedance value. And predicting target depth of discharge values corresponding to the cut-off voltages according to the first impedance value, the second impedance value and the third impedance value, and finally solving charge state related parameters including full charge capacity, residual capacity and relative charge state according to the target depth of discharge values. The method comprises the steps of obtaining at least three groups of current data by adjusting a variable resistor, solving a first impedance value, a second impedance value and a third impedance value based on a preset function, predicting charge state related parameters including full charge capacity, residual capacity and relative charge state, and predicting a more accurate predicted voltage value according to the first impedance value, the second impedance value and the third impedance value, so that the obtained charge state related parameters are more accurate, and user experience is greatly improved.
Drawings
FIG. 1 is a schematic diagram of an embodiment of a method for predicting a state of charge related parameter according to the present application;
FIG. 2 is a schematic diagram of another embodiment of a method for predicting a state of charge related parameter according to the present application;
FIG. 3 is a schematic diagram of the battery chemistry at 25 degrees Celsius of the present application;
FIG. 4 is a schematic view of one embodiment of a battery management system of the present application;
fig. 5 is a schematic diagram of another embodiment of the battery management system of the present application.
Detailed Description
The embodiment of the application provides a method and a device for predicting charge state related parameters based on impedance decomposition.
The existing method solves the relative state of charge value of the battery through the direct current internal resistance solved by a linear method, however, the direct current internal resistance solved by the linear method is not accurate enough, so that the related parameters of the state of charge of the battery are not accurate enough. The method and the device for predicting the state of charge related parameters based on impedance decomposition can solve the problems.
The method and the device for predicting the state of charge related parameters based on impedance decomposition provided by the present application are described below. Referring to fig. 1, an embodiment of a method for predicting a state of charge related parameter according to the present application includes:
101. when the discharging process of the battery meets the preset condition, obtaining multiple groups of target current values and multiple groups of target voltage values of the battery by adjusting the variable resistor for multiple times from a first time point to a second time point, wherein the adjusting time length of the variable resistor at each time is the preset time length corresponding to the current adjustment;
and when the preset conditions are met, adjusting the variable resistor for multiple times to obtain multiple groups of target current values and multiple groups of target voltage values. The target current value has at least three sets of current data, the preset duration is duration of each set of current, and the durations of the currents corresponding to the target current values of each set may be set to be the same or different, and are not limited herein. The target voltage values are actual voltages at two ends of the battery when the battery is connected with the load, correspond to the target current values, and are at least three groups which can be measured by a voltmeter. The variable resistor can be arranged inside or outside the chip system and can also be controlled through the MOS tube. The first time point can be regarded as the time when the preset condition is met, and the second time point can be regarded as the time after the first time point is subjected to at least three preset durations.
Specifically, when the discharge current increase value of the battery is larger than a preset threshold value, the variable resistor is controlled to obtain a target current value and a target voltage value. The preset threshold value can be set according to requirements. For example, when the user only runs office software on a notebook computer, the discharge current is relatively small, such as 0.2C. After a period of time, the user wants to play a game, at which time the power is increased and the discharge current is increased, which is 1C. The preset threshold is preset to be 0.5C, and at this time, the discharge current is increased by 1C-0.2C =0.8C > 0.5C, so that the resistance value in the variable resistance adjusting circuit can be controlled to obtain the target current value and the target voltage value.
Specifically, it is also possible to control the variable resistor to obtain the target current value when the discharge current of the battery continues for a preset time period. The preset time period can be preset according to requirements. For example, if the preset time period is set to 5 minutes and the discharge current of the notebook computer of the user continues for 5 minutes, the variable resistor is controlled to obtain the target current value and the target voltage value.
102. Calculating a first depth of discharge value and a first open-circuit voltage value of the battery at a second time point, and acquiring a first temperature value of the battery at the second time point;
and obtaining a first depth of discharge value through an initial depth of discharge value, a sampling capacity value and a maximum chemical discharge capacity value, wherein the initial depth of discharge value is the depth of discharge value of the battery at a first time point, and the sampling capacity value is the current integral of the battery from the first time point to a second time point, and can be measured by a coulometer. Specifically, the first depth of discharge value is obtained by the following formula:
Figure 281335DEST_PATH_IMAGE014
；
wherein the content of the first and second substances,
Figure DEST_PATH_IMAGE015
is a first depth of discharge value;
Figure 897125DEST_PATH_IMAGE016
is the initial depth of discharge value, is a known quantity;
Figure DEST_PATH_IMAGE017
is a sampling capacity value measured by a coulometer;
Figure 128386DEST_PATH_IMAGE018
the maximum chemical discharge capacity represents that when the battery cell is not loaded, the current is 0, and generally only changes with the aging state according to the maximum capacity which can be released by the open circuit voltage, and the value does not change in a discharge process and can be used as a reference.
And acquiring a first temperature value of the battery at a second time point. The first temperature value is a temperature value of the surface of the battery at the second time point, corresponds to the first depth of discharge value, and can be measured by the thermistor. For example, if the temperature of the surface of the battery measured by the thermistor is T1, the first temperature value is T1.
The first depth of discharge value and a corresponding first open-circuit voltage value at a first temperature may be determined according to a preset calculation relationship among open-circuit voltage, temperature, and depth of discharge. Specifically, a first open-circuit voltage value is obtained through a first discharge depth value and a first temperature based on an open-circuit voltage table at each preset temperature or a temperature coefficient table at each preset discharge depth (DOD), wherein the open-circuit voltage table is a set of data representing a preset corresponding relationship between open-circuit voltage (OCV) and the discharge depth at each preset temperature, and the temperature coefficient table is a change range of the OCV at each preset discharge depth with a temperature change of 1 ℃ or 1K. And obtaining a first open-circuit voltage value based on the open-circuit voltage table or the temperature coefficient table through the first depth of discharge value and the first temperature value.
In addition, the open-circuit voltage table and the temperature coefficient table may be constructed in advance by the following steps. The battery cell is charged to 100% according to a standard charging process defined by a specification, then is kept stand for a certain time, and is charged to a cut-off voltage from full charge to full charge with a standard of small current of 0.02-0.2C, specifically 80 mA-800 mA if the battery is 4000 mAh. And solving Chem-ID tables of the test battery at different temperatures, namely open-circuit voltage values corresponding to depth of discharge values at different temperatures. The depth of discharge was 5% at one point, and 21 points were obtained at 0 to 100%. Considering that the temperature range of the battery is-40 ℃ to 75 ℃, except for the normal temperature of 25 ℃, as a reference, one temperature interval of 25 ℃, 10 ℃,0 ℃, 10 ℃, 20 ℃, 40 ℃,35 ℃,45 ℃,60 ℃ and 75 ℃ can be set every 10 ℃ to 20 ℃, and there are 10 temperature points, and an open circuit voltmeter at 10 temperatures, for example, the open circuit voltmeter at 25 ℃ in fig. 3, can be obtained.
The temperature T is taken as an X axis, 10 OCVs under the same DOD are taken as a Y axis, and the obtained slope is dOCV/dT, namely the temperature coefficient. And obtaining the temperature coefficient table by taking the temperature coefficients under different DODs.
103. Calculating a first impedance value, a second impedance value and a third impedance value of the battery at a second time point through the first depth of discharge value, the first open-circuit voltage value, the multiple groups of target current values, the multiple groups of target voltage values, the first temperature value and the multiple preset durations;
and calculating the known quantity obtained by the steps to obtain a first impedance value, a second impedance value and a third impedance value based on a preset function. The first impedance value is the sum of the ohmic impedance value and the Faraday impedance value of the battery at the second time point, the second impedance value is the electrochemical reaction impedance value of the battery at the second time point, and the third impedance value is the concentration polarization impedance value of the battery at the second time point. Specifically, the first impedance value, the second impedance value, and the third impedance value may be calculated by the following formulas:
Figure 44389DEST_PATH_IMAGE001
；
wherein the content of the first and second substances,
Figure 702904DEST_PATH_IMAGE002
in order to polarize the over-potential,
Figure 337147DEST_PATH_IMAGE003
is the first open-circuit voltage value and,
Figure 372099DEST_PATH_IMAGE004
in order to be the value of the target voltage,
Figure DEST_PATH_IMAGE019
for the purpose of the target current value, the current value,
Figure 871171DEST_PATH_IMAGE006
for the purpose of the first value of the impedance,
Figure 966166DEST_PATH_IMAGE007
for the first depth-of-discharge value,
Figure 822126DEST_PATH_IMAGE020
is the value of the first temperature, and is,
Figure 926348DEST_PATH_IMAGE009
as a function of the impedance of the electrochemical reaction,
Figure 285786DEST_PATH_IMAGE010
for the value of the second impedance to be,
Figure 817261DEST_PATH_IMAGE011
for the diffusion function followed by the third impedance value,
Figure 160518DEST_PATH_IMAGE012
the time is the preset time length,
Figure 802852DEST_PATH_IMAGE013
is the third impedance value.
The target current value and the preset duration can be set by controlling the variable resistor according to requirements. For example, 5 sets of current data are set:
a.1.0C to 2.0C DC 1s to 2s
b.0.8C to 1.0C DC 1s to 3s
c.0.3C to 0.7C DC 3s to 5s
d.0.2C to 0.3C DC 8s to 10s
e.0.05C to 0.2C DC 10s to 15s
The test flow is controlled within 25s to 35s, and the depth of discharge value is changed within 0.5 percent. The first impedance value, the second impedance value and the third impedance value can be obtained based on the above formula through 5 groups of data and other known quantities.
104. Predicting a target depth of discharge value corresponding to the cut-off voltage according to the first impedance value, the second impedance value and the third impedance value;
and predicting a target depth of discharge value corresponding to the cut-off voltage according to the first impedance value, the second impedance value and the third impedance value, specifically, obtaining a fourth impedance value, a fifth impedance value, a sixth impedance value, a second depth of discharge value, a second open-circuit voltage value and a second temperature value according to the first impedance value, the second impedance value and the third impedance value. The second depth of discharge value is a set depth of discharge value, the second open-circuit voltage value is a voltage corresponding to the second depth of discharge value, the second temperature value is a predicted temperature of the surface of the battery when the depth of discharge value of the battery is the second depth of discharge value, the fourth impedance value is a sum of an ohmic impedance value and a faradaic impedance value in the battery when the battery is at the second temperature, the fifth impedance value is an electrochemical reaction impedance value in the battery when the battery is at the second temperature, and the sixth impedance value is a concentration polarization impedance value in the battery when the battery is at the second temperature.
And then predicting a target depth of discharge value corresponding to the cut-off voltage according to the target data. The target data is a set of various data under different discharge depths and different temperatures, and comprises values of various impedances of the battery. The target data comprises a target current value, a first depth of discharge value, a first open-circuit voltage value, a target voltage value, a first temperature value, a preset duration, a fourth impedance value, a fifth impedance value, a sixth impedance value, a second depth of discharge value, a second open-circuit voltage value and a second temperature value. The target depth of discharge value is a depth of discharge value corresponding to a maximum value of the predicted voltage that is less than or equal to the cutoff voltage. The cut-off voltage is typically 3V.
105. And obtaining the state of charge related parameters of the battery at the second time point according to the target depth of discharge value, wherein the state of charge related parameters comprise the full charge capacity, the residual capacity and the relative state of charge of the battery.
And obtaining the state-of-charge related parameters of the battery according to the target depth of discharge value, wherein the state-of-charge related parameters comprise the full charge capacity, the residual capacity and the relative state of charge of the battery. Specifically, the full charge capacity and the residual capacity can be obtained according to the target depth of discharge value, and finally the full charge capacity and the residual capacity are divided by the relative state of charge value of the battery.
In the embodiment of the application, the variable resistor is adjusted to obtain at least three groups of target current values and at least three groups of target voltage values after the preset condition is met, and then a first depth of discharge value and a first open-circuit voltage value are calculated to obtain a first temperature value. And then calculating according to the obtained known quantity to obtain a first impedance value, a second impedance value and a third impedance value. And predicting target depth of discharge values corresponding to the cut-off voltages according to the first impedance value, the second impedance value and the third impedance value, and finally solving charge state related parameters including full charge capacity, residual capacity and relative charge state according to the target depth of discharge values. The method comprises the steps of obtaining at least three groups of current data by adjusting the variable resistor, solving a first impedance value, a second impedance value and a third impedance value based on a preset function, predicting relevant parameters of the state of charge, including the full charge capacity, the residual capacity and the relative state of charge, and predicting a voltage value more accurately according to the first impedance value, the second impedance value and the third impedance value, so that the obtained relevant parameters of the state of charge are more accurate, and the user experience is greatly improved.
Referring to fig. 2, another embodiment of the relative state of charge analysis method of the present application includes:
201. when the discharging process of the battery meets a preset condition, obtaining multiple groups of target current values and multiple groups of target voltage values of the battery by adjusting the variable resistor for multiple times from a first time point to a second time point, wherein the adjusting time length of each variable resistor is a preset time length corresponding to the current adjustment;
and when the preset conditions are met, adjusting the variable resistor for multiple times to obtain multiple groups of target current values and multiple groups of target voltage values. The target current value has at least three sets of current data, the preset duration is duration of each set of current, and the durations of the currents corresponding to the target current values of each set may be set to be the same or different, and are not limited herein. The target voltage values are actual voltages at two ends of the battery when the battery is connected with the load, correspond to the target current values, and are at least three groups which can be measured by a voltmeter. The variable resistor can be arranged inside or outside the chip system and can also be controlled through the MOS tube. The first time point can be regarded as the time when the preset condition is met, and the second time point can be regarded as the time after the first time point is subjected to at least three preset durations.
Specifically, when the discharge current increase value of the battery is larger than a preset threshold value, the variable resistor is controlled to obtain a target current value and a target voltage value. The preset threshold value can be set according to requirements. For example, when the user only runs office software on a notebook computer, the discharge current is relatively small, such as 0.2C. After a period of time, the user wants to play a game, at which time the power is increased and the discharge current is increased, which is 1C. The preset threshold is preset to be 0.5C, and at this time, the discharge current is increased by 1C-0.2C =0.8C > 0.5C, so that the resistance value in the variable resistance adjusting circuit can be controlled to obtain the target current value and the target voltage value.
Specifically, it is also possible to control the variable resistor to obtain the target current value when the discharge current of the battery continues for a preset time period. The preset time period can be preset according to the requirement. For example, the preset time period is set to 5 minutes, and the discharge current of the notebook computer of the user continues for 5 minutes, the variable resistor is controlled to obtain the target current value and the target voltage value.
202. Calculating a first depth of discharge value and a first open-circuit voltage value of the battery at a second time point, and acquiring a first temperature value of the battery at the second time point;
and obtaining a first depth of discharge value through the initial depth of discharge value, the sampling capacity value and the maximum chemical discharge capacity value, wherein the initial depth of discharge value is the depth of discharge value of the battery at a first time point, and the sampling capacity value is the current integral of the battery from the first time point to a second time point, and can be measured by a coulometer. Specifically, the first depth of discharge value is obtained by the following formula:
Figure 282375DEST_PATH_IMAGE014
；
wherein, the first and the second end of the pipe are connected with each other,
Figure DEST_PATH_IMAGE021
is a first depth of discharge value;
Figure 719172DEST_PATH_IMAGE016
is the initial depth of discharge value, is a known quantity;
Figure 284146DEST_PATH_IMAGE022
is a sampling capacity value measured by a coulometer;
Figure 730170DEST_PATH_IMAGE018
the maximum chemical discharge capacity represents that when the battery cell is not loaded, the current is 0, and generally only changes with the aging state according to the maximum capacity which can be released by the open circuit voltage, and the value does not change in a discharge process and can be used as a reference.
And acquiring a first temperature value of the battery at a second time point. The first temperature value is the temperature value of the surface of the battery at the second time point, corresponds to the first depth of discharge value, and can be measured by the thermistor. For example, if the temperature of the surface of the battery measured by the thermistor is T1, the first temperature value is T1.
The first depth of discharge value and a corresponding first open-circuit voltage value at a first temperature may be determined according to a preset calculation relationship among open-circuit voltage, temperature, and depth of discharge. Specifically, a first open-circuit voltage value is obtained through a first discharge depth value and a first temperature based on an open-circuit voltage table at each preset temperature or a temperature coefficient table at each preset discharge depth (DOD), wherein the open-circuit voltage table is a set of data representing a preset corresponding relationship between open-circuit voltage (OCV) and the discharge depth at each preset temperature, and the temperature coefficient table is a change range of the OCV at each preset discharge depth with a temperature change of 1 ℃ or 1K. And obtaining a first open-circuit voltage value based on the open-circuit voltage table or the temperature coefficient table through the first depth of discharge value and the first temperature value.
In addition, the open-circuit voltage table and the temperature coefficient table may be constructed in advance by the following steps. The battery cell is charged to 100% according to a standard charging flow defined by a specification, then is kept stand for a certain time, and is charged to a cut-off voltage from full charge and discharge according to a standard of a small current of 0.02-0.2C, specifically 80 mA-800 mA if the battery is 4000 mAh. And solving Chem-ID tables of the test battery at different temperatures, namely open-circuit voltage values corresponding to depth of discharge values at different temperatures. The depth of discharge was 5% at one point, and 21 points were obtained at 0 to 100%. Considering that the temperature range of the battery is-40 ℃ to 75 ℃, apart from the normal temperature of 25 ℃, a temperature range of 25 ℃, 10 ℃,0 ℃, 10 ℃, 20 ℃, 40 ℃,35 ℃,45 ℃,60 ℃ and 75 ℃ can be set every 10 ℃ to 20 ℃ except for the normal temperature of 25 ℃ as a reference, and then 10 temperature points can be obtained, and an open-circuit voltmeter at 10 temperatures can be obtained.
The temperature T is taken as an X axis, 10 OCVs under the same DOD are taken as a Y axis, and the obtained slope is dOCV/dT, namely the temperature coefficient. And obtaining the temperature coefficient table by taking the temperature coefficients under different DODs.
203. Calculating a first impedance value, a second impedance value and a third impedance value of the battery at a second time point through the first depth of discharge value, the first open-circuit voltage value, the multiple groups of target current values, the multiple groups of target voltage values, the first temperature value and the multiple preset durations;
and calculating the known quantity obtained by the steps to obtain a first impedance value, a second impedance value and a third impedance value based on a preset function. The first impedance value is the sum of the ohmic impedance value and the Faraday impedance value of the battery at the second time point, the second impedance value is the electrochemical reaction impedance value of the battery at the second time point, and the third impedance value is the concentration polarization impedance value of the battery at the second time point. Specifically, the first impedance value, the second impedance value, and the third impedance value may be calculated by the following formulas:
Figure 64200DEST_PATH_IMAGE001
；
wherein the content of the first and second substances,
Figure 937478DEST_PATH_IMAGE002
in order to polarize the over-potential,
Figure 989748DEST_PATH_IMAGE003
is the first open-circuit voltage value and,
Figure 973884DEST_PATH_IMAGE004
in order to be the value of the target voltage,
Figure 427999DEST_PATH_IMAGE005
for the purpose of the target current value, the current value,
Figure 472179DEST_PATH_IMAGE006
for the purpose of the first value of the impedance,
Figure 11744DEST_PATH_IMAGE007
for the first depth-of-discharge value,
Figure 799572DEST_PATH_IMAGE008
is the value of the first temperature, and is,
Figure 108193DEST_PATH_IMAGE009
as a function of the impedance of the electrochemical reaction,
Figure 323274DEST_PATH_IMAGE010
for the value of the second impedance to be,
Figure 84557DEST_PATH_IMAGE011
for the diffusion function followed by the third impedance value,
Figure 676075DEST_PATH_IMAGE012
the time is the preset time length and is the time length,
Figure 839203DEST_PATH_IMAGE013
is the third impedance value.
The target current value and the preset duration can be set by controlling the variable resistor according to requirements. For example, 5 sets of current data are set:
a.1.0C to 2.0C DC 1s to 2s
b.0.8C to 1.0C DC 1s to 3s
c.0.3C to 0.7C DC 3s to 5s
d.0.2C to 0.3C DC 8s to 10s
e.0.05C to 0.2C DC 10s to 15s
The test flow is controlled within 25s to 35s, and the depth of discharge value is changed within 0.5 percent. The first impedance value, the second impedance value and the third impedance value can be obtained based on the above formula through 5 groups of data and other known quantities.
204. Obtaining a second depth of discharge value according to the first depth of discharge value and the segmented depth of discharge value;
and obtaining a second depth of discharge value according to the first depth of discharge value and the segmented depth of discharge value, wherein the segmented depth of discharge value is a preset value. Specifically, the second depth of discharge value may be obtained by the following formula:
Figure DEST_PATH_IMAGE023
；
wherein the content of the first and second substances,
Figure 694027DEST_PATH_IMAGE024
is the value of the second depth of discharge value,
Figure DEST_PATH_IMAGE025
is a value of the first depth of discharge value,
Figure 942605DEST_PATH_IMAGE026
the depth value of the sectional discharge can be set according to the requirement,
Figure DEST_PATH_IMAGE027
are integers.
205. Obtaining a second open-circuit voltage value, a second temperature value, a fourth impedance value, a fifth impedance value and a sixth impedance value according to the first impedance value, the second impedance value, the third impedance value, the second depth of discharge value and a preset calculation relation among the open-circuit voltage, the depth of discharge and the temperature;
based on a preset calculation relationship among the open-circuit voltage, the depth of discharge and the temperature, or based on an open-circuit voltage table or a temperature coefficient table, and by combining the first impedance value, the second impedance value, the third impedance value and the second depth of discharge value, a second open-circuit voltage value, a second temperature value, a fourth impedance value, a fifth impedance value and a sixth impedance value can be calculated.
For ease of understanding, steps 204 to 205 are described below by way of example. After the first impedance value r1, the second impedance value Rct1 and the third impedance value Rc1 are obtained, when the battery surface temperature value measured by the thermistor is Tc1, the current is I, the preset time period is T, the target voltage value is U, the first depth of discharge value is DOD1 and the first open-circuit voltage value is OCV1, the known values are substituted into the equation of step 203 to obtain the polarization overvoltage Δ U1, then the temperature rise Δ T2 of the next DOD point (i.e., DOD2= DOD1+ dDOD 2) can be obtained according to the heating power P = I × Δ U1 of the battery and considering the influence of heat dissipation, and then the temperature rise Δ T2 of the next DOD point (i.e., DOD2= DOD1+ dDOD 2) can be obtained according to the temperature Tc = Tc 7378 = Tc1+ Δ T2 corresponding to DOD2, and the OCV2 can be obtained according to the DOD2 and Tc 84 and can be obtained according to an open-voltage table or a temperature table query, and then the equations 39r 4642, Rct2 and Rc2 can be obtained by using the equations. Next, the next DOD point (DOD 3= DOD1+ dDOD × 2) is also based on the data (r 2, Rct2, Rc2 and Tc 2) of the previous DOD point, a temperature rise Δ T3 is predicted to find the temperature Tc3, OCV3 is then obtained, and finally r3, Rct3 and Rc3 are obtained, and so on.
206. Adjusting the fourth impedance value, the fifth impedance value and the sixth impedance value according to a preset proportion;
and adjusting the fourth impedance value, the fifth impedance value and the sixth impedance value according to a preset proportion to obtain an adjusted fourth impedance value, an adjusted fifth impedance value and an adjusted sixth impedance value, for example, data corresponding to the current three DOD points are obtained, and a fixed proportion is obtained according to the data, so that each impedance value corresponding to the DOD point is adjusted, and the data are more accurate.
207. Respectively judging whether the adjusted fourth impedance value, the adjusted fifth impedance value and the adjusted sixth impedance value are valid data or not based on preset relations among the impedances, the depth of discharge and the temperature, if so, executing a step 209, and if not, executing a step 208;
the impedance table comprises a sum range of ohmic impedance values and Faraday impedance values, a range of electrochemical reaction impedance values and a range of concentration polarization impedance values corresponding to different temperatures and different discharge depths.
208. Replacing the impedance values which do not belong to the effective data based on the preset relation among the impedance, the depth of discharge and the temperature to obtain a fourth impedance value, a fifth impedance value and a sixth impedance value which belong to the effective data;
values that are not within the preset valid range are replaced based on the impedance table. For example, the three impedance values of 5% DOD at 20 ℃ calculated according to the above steps are r =26m Ω, Rct =32m Ω, and Rc =5m Ω, respectively. The values of the two impedance tables are known as: three impedance values of 5% DOD at 10 ℃ were r =25m Ω, Rct =30m Ω, Rc =5m Ω, respectively; the three impedance values of 5% DOD at 25 ℃ were r =31m Ω, Rct =36m Ω, Rc =8m Ω, respectively. 26 is between [25, 31], 32 is between [30, 36] and 5 is between [5, 8], then the calculated data is valid data. If the three calculated impedance values of 5% DOD at 20 ℃ are r =35m Ω, Rct =50m Ω, Rc =10m Ω,35 is not between [25, 31], 50 is not between [30, 36], and 10 is not between [5, 8], the calculated data is not valid data. And replacing the invalid data by an interpolation method, and calculating according to the boundary condition difference to obtain r =29m Ω, Rct =34m Ω and Rc =7m Ω.
209. Calculating according to the target data to obtain a predicted voltage;
the predicted voltage is calculated according to the target data, wherein the target data includes the first impedance value, the second impedance value, the third impedance value, the fourth impedance value, the fifth impedance value, the sixth impedance value and other related data corresponding to the impedances, or the related data of each DOD point set in the above steps, and the predicted voltage is the predicted voltage at two ends when the battery is connected to the load, that is, the polarization overvoltage, and can be calculated according to the target data based on the equation in step 203.
210. Determining the depth-of-discharge value corresponding to the maximum value smaller than or equal to the cutoff voltage in the predicted voltage as a target depth-of-discharge value;
and determining the depth-of-discharge value corresponding to the maximum value of the predicted voltage which is less than or equal to the cutoff voltage as the target depth-of-discharge value. There are multiple predicted voltages obtained in step 209, the number of which is consistent with the number of DOD points. And after determining the maximum value of the predicted voltage which is less than or equal to the cut-off voltage, finding out a corresponding DOD value and determining the DOD value as a target depth of discharge value. Wherein, the target depth of discharge is the depth of cut-off voltage depth of discharge (DODEDV),
specifically, the target depth of discharge value is obtained through the following formula:
when the remaining DOD is segmented once,
Figure 541077DEST_PATH_IMAGE028
；
when the remaining DOD is sub-segmented,
Figure DEST_PATH_IMAGE029
；
wherein the content of the first and second substances,
Figure 558711DEST_PATH_IMAGE030
；
Figure DEST_PATH_IMAGE031
is the initial depth of discharge value, is a known quantity;
Figure 584436DEST_PATH_IMAGE032
is a sampling capacity value measured by a coulometer;
Figure DEST_PATH_IMAGE033
in order to maximize the value of the chemical discharge capacity, which represents that the current of the battery cell is 0 when the battery cell is not loaded, according to the maximum capacity which can be discharged by the open circuit voltage,
Figure 320311DEST_PATH_IMAGE034
and
Figure DEST_PATH_IMAGE035
is an integer which is the number of the whole,
Figure 722474DEST_PATH_IMAGE036
and
Figure 594615DEST_PATH_IMAGE037
in order to segment the depth-of-discharge value,
Figure 587978DEST_PATH_IMAGE038
。
specifically, the cutoff voltage is set to be EDV (generally 3V), the DOD points are divided according to a fixed ratio (for example, 3% to 5% DOD), after each DOD is obtained, a prediction voltage Ut1 obtained by an equation from a first DOD point (DOD 1= DOD0+ DODa) and related data is determined, whether Ut1 is satisfied or not is determined, that is, DOD1 is determined as a target depth of discharge value, if not, the next stage simulation is performed, a prediction voltage Ut2 is determined at a second DOD point (DOD 2= DOD0+ DODa + dDOD 1), whether Ut1 is satisfied or not, that is, DOD2 is determined as a target depth of discharge value, if not, the next stage simulation is performed, a third DOD point (DOD 3= DOD0+ DOD1 × 2), a fourth point (DOD 4= DOD0+ DOD 3985 + 3 × 1), and so on. When the determination is made to be true, the next segment dDOD may be subdivided (e.g., 1% DOD) for improving accuracy, for example, if the target depth-of-discharge value is between DOD4 and DOD5, then dDOD2 is set to 1% DOD, the target depth-of-discharge value is continuously approximated, the first value in the secondary segment is found to be DOD = DOD4+ dDOD2 × 1, and so on, and the process is similar to the above.
211. And obtaining the state of charge related parameters of the battery at the second time point according to the target depth of discharge value, wherein the state of charge related parameters comprise the full charge capacity, the residual capacity and the relative state of charge of the battery.
And obtaining the state of charge related parameters of the battery at the second time point according to the target depth of discharge value, wherein the state of charge related parameters comprise the full charge capacity, the residual capacity and the relative state of charge of the battery. Specifically, the Full Charge Capacity (FCC) and the Residual Capacity (RC) are determined first, and then the relative state of charge values are determined. It can be calculated by the following formula:
Figure 76729DEST_PATH_IMAGE039
；
when the remaining DODs are segmented once,
Figure 276723DEST_PATH_IMAGE040
；
when the remaining DOD is sub-segmented,
Figure DEST_PATH_IMAGE041
；
Figure 3370DEST_PATH_IMAGE042
；
wherein the content of the first and second substances,
Figure 167635DEST_PATH_IMAGE043
in order to have a full charge capacity value,
Figure DEST_PATH_IMAGE044
as a value of the remaining capacity,
Figure 346944DEST_PATH_IMAGE045
in order to maximize the value of the chemical discharge capacity,
Figure DEST_PATH_IMAGE046
in order to be the target depth-of-discharge value,
Figure 90909DEST_PATH_IMAGE047
in order to segment the depth-of-discharge value,
Figure DEST_PATH_IMAGE048
the number of segmented depth-of-discharge values corresponding to the target depth-of-discharge value,
Figure 937642DEST_PATH_IMAGE049
is the relative state of charge value.
In this embodiment, after the preset condition is satisfied, the variable resistor is adjusted to obtain at least three sets of target current values and at least three sets of target voltage values, and then the first depth of discharge value and the first open-circuit voltage value are calculated to obtain the first temperature value. And then calculating according to the obtained known quantity to obtain a first impedance value, a second impedance value and a third impedance value. And predicting target depth of discharge values corresponding to the cut-off voltages according to the first impedance value, the second impedance value and the third impedance value, and finally solving charge state related parameters including full charge capacity, residual capacity and relative charge state according to the target depth of discharge values. The method comprises the steps of obtaining at least three groups of current data by adjusting a variable resistor, solving a first impedance value, a second impedance value and a third impedance value based on a preset function, then solving a fourth impedance value, a fifth impedance value and a sixth impedance value, adjusting the fourth impedance value, the fifth impedance value and the sixth impedance value to better predict the relevant parameters of the state of charge, including the full charge capacity, the residual capacity and the relative state of charge, and according to the adjusted fourth impedance value, the predicted voltages of the fifth impedance value and the sixth impedance value are more accurate, so that the obtained relevant parameters of the state of charge are more accurate, the precision of the relevant parameters of the state of charge can be 2% at normal temperature, the precision can meet the requirement of <5% at low temperature, and the user experience is greatly improved.
The battery management system of the present application is described below. Referring to fig. 4, an embodiment of a battery management system according to the present application includes:
an adjusting unit 401, configured to, when a discharging process of a battery meets a preset condition, obtain multiple sets of target current values and multiple sets of target voltage values of the battery by adjusting a variable resistor multiple times from a first time point to a second time point, where an adjustment duration of the variable resistor at each time is a preset duration corresponding to the current adjustment;
a processing unit 402, configured to calculate a first depth of discharge value and a first open-circuit voltage value of the battery at the second time point, and obtain a first temperature value of the battery at the second time point;
a calculating unit 403, configured to calculate, according to the first depth of discharge value, the first open-circuit voltage value, the multiple sets of target current values, the multiple sets of target voltage values, the first temperature value, and the multiple preset durations, a first impedance value, a second impedance value, and a third impedance value of the battery at the second time point, where the first impedance value is a sum of an ohmic impedance value and a faraday impedance value of the battery, the second impedance value is an electrochemical reaction impedance value of the battery, and the third impedance value is a concentration polarization impedance value of the battery;
a prediction unit 404, configured to predict a target depth of discharge value corresponding to a cut-off voltage according to the first impedance value, the second impedance value, and the third impedance value;
the processing unit 402 is further configured to obtain state of charge related parameters of the battery at the second time point according to the target depth of discharge value, where the state of charge related parameters include a full charge capacity, a residual capacity, and a relative state of charge of the battery.
In this embodiment, after the preset condition is satisfied, the adjusting unit 401 adjusts the variable resistor to obtain at least three sets of target current values and at least three sets of target voltage values, and then the processing unit 402 calculates a first depth of discharge value and a first open-circuit voltage value to obtain a first temperature value. Then, the calculation unit 403 calculates the first impedance value, the second impedance value, and the third impedance value according to the obtained known quantities. The prediction unit 404 predicts a target depth of discharge value corresponding to the cut-off voltage according to the first impedance value, the second impedance value, and the third impedance value, and finally obtains state of charge related parameters including a full charge capacity, a residual capacity, and a relative state of charge according to the target depth of discharge value. The method comprises the steps of obtaining at least three groups of current data by adjusting the variable resistor, solving a first impedance value, a second impedance value and a third impedance value based on a preset function, predicting relevant parameters of the state of charge, including the full charge capacity, the residual capacity and the relative state of charge, and predicting a voltage value more accurately according to the first impedance value, the second impedance value and the third impedance value, so that the obtained relevant parameters of the state of charge are more accurate, and the user experience is greatly improved.
The functions and processes executed by each unit in the battery management system of this embodiment are similar to those executed by the battery management system in fig. 1 to 3, and are not described again here.
Fig. 5 is a schematic structural diagram of a battery management system according to an embodiment of the present disclosure, where the battery management system 500 may include one or more Central Processing Units (CPUs) 501 and a memory 505, and one or more applications or data are stored in the memory 505.
Memory 505 may be volatile storage or persistent storage, among others. The program stored in memory 505 may include one or more modules, each of which may include a sequence of instructions operating on a battery management system. Still further, the central processor 501 may be configured to communicate with the memory 505 to execute a series of instruction operations in the memory 505 on the battery management system 500.
The battery management system 500 may also include one or more power supplies 502, one or more input/output interfaces 504, and/or one or more operating systems, such as Windows Server, Mac OS XTM, UnixTM, Linux, FreeBSDTM, and the like.
The cpu 501 may perform the operations performed by the battery management system in the embodiments shown in fig. 1 to fig. 3, and detailed descriptions thereof are omitted here.
It is clear to those skilled in the art that, for convenience and brevity of description, the specific working processes of the above-described systems, apparatuses and units may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again.
In the several embodiments provided in the present application, it should be understood that the disclosed system, apparatus and method may be implemented in other manners. For example, the above-described apparatus embodiments are merely illustrative, and for example, the division of the units is only one logical division, and other divisions may be realized in practice, for example, a plurality of units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may be in an electrical, mechanical or other form.
The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.
In addition, functional units in the embodiments of the present application may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit. The integrated unit can be realized in a form of hardware, and can also be realized in a form of a software functional unit.
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: a U-disk, a removable hard disk, a read-only memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and the like.

Claims (10)

1. A battery management system state of charge related parameter prediction method based on impedance decomposition is characterized by comprising the following steps:
when the discharging process of the battery meets a preset condition, obtaining multiple groups of target current values and multiple groups of target voltage values of the battery by adjusting the variable resistor for multiple times from a first time point to a second time point, wherein the adjusting time length of the variable resistor at each time is a preset time length corresponding to the current adjustment;
calculating a first depth of discharge value and a first open-circuit voltage value of the battery at the second time point, and acquiring a first temperature value of the battery at the second time point;
calculating a first impedance value, a second impedance value and a third impedance value of the battery at the second time point according to the first depth of discharge value, the first open-circuit voltage value, the multiple groups of target current values, the multiple groups of target voltage values, the first temperature value and the multiple preset durations, wherein the first impedance value is the sum of an ohmic impedance value and a faradaic impedance value of the battery, the second impedance value is an electrochemical reaction impedance value of the battery, and the third impedance value is a concentration polarization impedance value of the battery;
predicting a target depth of discharge value corresponding to a cut-off voltage according to the first impedance value, the second impedance value and the third impedance value;
and obtaining the state of charge related parameters of the battery at the second time point according to the target depth of discharge value, wherein the state of charge related parameters comprise the full charge capacity, the residual capacity and the relative state of charge of the battery.
2. The method of claim 1, wherein predicting the target depth of discharge value corresponding to a cutoff voltage according to the first impedance value, the second impedance value, and the third impedance value comprises:
calculating a fourth impedance value, a fifth impedance value, a sixth impedance value, a second depth of discharge value, a second open-circuit voltage value and a second temperature value according to the first impedance value, the second impedance value and the third impedance value, the second depth of discharge value is a set depth of discharge value, the second open-circuit voltage value is a voltage value corresponding to the second depth of discharge value, the second temperature value is a predicted temperature of a surface of the battery when the depth of discharge value of the battery is the second depth of discharge value, the fourth impedance value is a sum of an ohmic impedance value and a Faraday impedance value in the battery when the battery is at the second temperature value, the fifth impedance value is an impedance value of an electrochemical reaction in the battery when the battery is at the second temperature value, the sixth impedance value is a concentration polarization impedance value in the battery when the battery is at the second temperature value;
predicting a target depth of discharge value corresponding to a cut-off voltage according to target data, where the target data includes the target current value, the first depth of discharge value, the first open-circuit voltage value, the target voltage value, the first temperature value, the preset time duration, the fourth impedance value, the fifth impedance value, the sixth impedance value, the second depth of discharge value, the second open-circuit voltage value, and the second temperature value.
3. The method of claim 1, wherein the step of calculating a first impedance value, a second impedance value, and a third impedance value of the battery at the second time point according to the first depth of discharge value, the first open-circuit voltage value, the plurality of target current values, the plurality of target voltage values, the first temperature value, and the plurality of preset durations comprises:
calculating the first impedance value, the second impedance value and the third impedance value by the following formulas:
Figure DEST_PATH_IMAGE002
；
wherein the content of the first and second substances,
Figure DEST_PATH_IMAGE004
in order to polarize the over-potential,
Figure DEST_PATH_IMAGE006
is the value of the first open-circuit voltage,
Figure DEST_PATH_IMAGE008
in order to be the value of the target voltage,
Figure DEST_PATH_IMAGE010
in order to obtain the target current value,
Figure DEST_PATH_IMAGE012
for the purpose of the first value of the impedance,
Figure DEST_PATH_IMAGE014
for the first depth-of-discharge value,
Figure DEST_PATH_IMAGE016
is the value of the first temperature, and is,
Figure DEST_PATH_IMAGE018
as a function of the impedance of the electrochemical reaction,
Figure DEST_PATH_IMAGE020
for the value of the second impedance to be,
Figure DEST_PATH_IMAGE022
for the diffusion function followed by the third impedance value,
Figure DEST_PATH_IMAGE024
the time is the preset time length,
Figure DEST_PATH_IMAGE026
is the third impedance value.
4. The method according to claim 1, wherein when a discharging process of a battery satisfies a preset condition, obtaining a plurality of sets of target current values and a plurality of sets of target voltage values of the battery by adjusting a variable resistor for a plurality of times from a first time point to a second time point at which the preset condition is satisfied, comprises:
when the discharge current increase value of the battery is larger than a preset threshold value, the variable resistor is adjusted for multiple times from the first time point meeting the preset condition to the second time point through multiple preset time lengths, and the multiple groups of target current values and the multiple groups of target voltage values of the battery are obtained;
or the like, or, alternatively,
and when the discharging current of the battery lasts for a preset time period, the variable resistor is adjusted for multiple times from the first time point meeting the preset condition to the second time point through multiple preset time periods, so that the multiple groups of target current values and the multiple groups of target voltage values of the battery are obtained.
5. The method of claim 2, wherein calculating a fourth impedance value, a fifth impedance value, a sixth impedance value, a second depth of discharge value, a second open-circuit voltage value, and a second temperature value according to the first impedance value, the second impedance value, and the third impedance value comprises:
obtaining the second depth of discharge value according to the first depth of discharge value and the segmented depth of discharge value, wherein the segmented depth of discharge value is a preset value;
and obtaining the second open-circuit voltage value, the second temperature value, the fourth impedance value, the fifth impedance value and the sixth impedance value according to the first impedance value, the second impedance value, the third impedance value, the second depth of discharge value and the preset calculation relationship among the open-circuit voltage, the depth of discharge and the temperature.
6. The method of claim 5, wherein after obtaining the second open circuit voltage value, the second temperature value, the fourth impedance value, the fifth impedance value, and the sixth impedance value according to the first impedance value, the second impedance value, the third impedance value, the second depth of discharge value, and the preset calculation relationship among open circuit voltage, depth of discharge, and temperature, the method further comprises:
adjusting the fourth impedance value, the fifth impedance value and the sixth impedance value according to a preset proportion;
respectively judging whether the adjusted fourth impedance value, the adjusted fifth impedance value and the adjusted sixth impedance value are valid data or not based on the preset relations among the impedances, the depth of discharge and the temperature;
if not, replacing the impedance values which do not belong to the effective data based on the preset relation among the impedances, the depth of discharge and the temperature to obtain a fourth impedance value, a fifth impedance value and a sixth impedance value which belong to the effective data.
7. The method of claim 2, wherein predicting the target depth of discharge value corresponding to the cutoff voltage according to the target data comprises:
calculating according to the target data to obtain a predicted voltage, wherein the predicted voltage is the predicted voltage at two ends of the battery when the battery is connected with a load;
and determining the depth of discharge value corresponding to the maximum value smaller than or equal to the cut-off voltage in the predicted voltage as the target depth of discharge value.
8. A battery management system, comprising:
the device comprises an adjusting unit, a control unit and a control unit, wherein the adjusting unit is used for adjusting a variable resistor for multiple times from a first time point to a second time point when the discharging process of the battery meets a preset condition to obtain multiple groups of target current values and multiple groups of target voltage values of the battery, and the adjusting time length of the variable resistor at each time is a preset time length corresponding to the current adjustment;
the processing unit is used for calculating a first depth of discharge value and a first open-circuit voltage value of the battery at the second time point and acquiring a first temperature value of the battery at the second time point;
a calculating unit, configured to calculate, according to the first depth of discharge value, the first open-circuit voltage value, the multiple sets of target current values, the multiple sets of target voltage values, the first temperature value, and the multiple preset durations, a first impedance value, a second impedance value, and a third impedance value of the battery at the second time point, where the first impedance value is a sum of an ohmic impedance value and a faraday impedance value of the battery, the second impedance value is an electrochemical reaction impedance value of the battery, and the third impedance value is a concentration polarization impedance value of the battery;
the prediction unit is used for predicting a target depth of discharge value corresponding to a cut-off voltage according to the first impedance value, the second impedance value and the third impedance value;
the processing unit is further configured to obtain state of charge related parameters of the battery at the second time point according to the target depth of discharge value, where the state of charge related parameters include a full charge capacity, a residual capacity, and a relative state of charge of the battery.
9. A battery management system, comprising:
the system comprises a central processing unit, a memory and an input/output interface;
the memory is a transient memory or a persistent memory;
the central processor is configured to communicate with the memory and execute the operations of the instructions in the memory to perform the method of any of claims 1 to 7.
10. A computer-readable storage medium comprising instructions which, when executed on a computer, cause the computer to perform the method of any one of claims 1 to 7.
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