CN113933711A - SOC calibration algorithm - Google Patents

SOC calibration algorithm Download PDF

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CN113933711A
CN113933711A CN202010668927.8A CN202010668927A CN113933711A CN 113933711 A CN113933711 A CN 113933711A CN 202010668927 A CN202010668927 A CN 202010668927A CN 113933711 A CN113933711 A CN 113933711A
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soc
value
calibration
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battery
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秦威
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Zhejiang Chint Electrics Co Ltd
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Zhejiang Chint Electrics Co Ltd
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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]
    • G01R31/385—Arrangements for measuring battery or accumulator variables
    • G01R31/387—Determining ampere-hour charge capacity or SoC
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R35/00—Testing or calibrating of apparatus covered by the other groups of this subclass
    • G01R35/005—Calibrating; Standards or reference devices, e.g. voltage or resistance standards, "golden" references

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Abstract

An SOC calibration algorithm comprising the steps of, step S1: obtaining a coulomb efficiency table according to test data of the material of the battery cell at different temperatures and different currents, and obtaining a total capacity value of the battery by using the coulomb efficiency table; step S2: acquiring a battery state; when the battery is in a charging state, comparing the SOC value with the magnitude of M, and if the SOC value is more than 0 and less than M, calculating the SOC value by adopting an ampere-hour integration algorithm; if the SOC value is equal to M, entering advanced calibration; if the SOC value is more than M and less than 100%, a real-time voltage calibration method is adopted; when the battery is in a discharging state, comparing the SOC value with the N value, and if the SOC value is larger than N, calculating the SOC value by adopting an ampere-hour integration algorithm; if the SOC value is equal to N, entering advanced calibration; if the SOC value is more than 0 and less than N, a real-time voltage calibration method is adopted. The SOC value of the invention has higher precision, and can enter a voltage calibration state in advance, thereby avoiding the SOC deviation from reaching the charging terminal or the discharging terminal for calibration, reducing the deviation rate of the SOC and greatly reducing the data volume.

Description

SOC calibration algorithm
Technical Field
The invention relates to evaluation of remaining battery power, in particular to an SOC calibration algorithm.
Background
State of Charge (SOC) is the ratio of the remaining capacity of a battery after it has been used for a period of time or left unused for an extended period of time to its capacity in a fully charged StateUsually expressed as a percentage, can be expressed by the following formula:
Figure BDA0002581579950000011
SOC is an important parameter in a Battery Management System (BMS), and many functions in the BMS are based on SOC. The battery with the same capacity and the battery with higher SOC precision can have higher endurance mileage, if the battery does not have accurate SOC, the BMS cannot normally work due to the addition of more protection functions, so that the battery is in a protection state, and the service life of the battery is not prolonged favorably. Therefore, the SOC estimation with high accuracy can effectively reduce the battery cost.
There are several commonly used SOC algorithms: algorithms based on ampere-hour integration, algorithms based on Open Circuit Voltage (OCV) calibration, etc., but even small error integrals (due to the accuracy of the sensor and the limited sampling interval) gradually cause the SOC to become inaccurate during actual testing. When the battery is fully charged or discharged and left standing for a while, calibration is performed based on the OCV voltage, but it is not so many cases that such conditions are satisfied during actual use of the battery, so it is difficult to perform SOC calibration. Therefore, it is necessary to obtain an algorithm for accurately calculating the SOC value to reduce the maintenance cost of the battery.
Disclosure of Invention
The invention aims to overcome the defects of the existing evaluation system and provides an SOC calibration algorithm.
In order to achieve the purpose, the invention adopts the following technical scheme:
an SOC calibration algorithm comprising the steps of,
step S1: obtaining a coulombic efficiency table according to test data of materials of the battery cell at different temperatures and different currents, obtaining a total capacity value of the battery cell by using a rated total capacity value of the battery cell and the coulombic efficiency table, and obtaining and storing an SOC-voltmeter of the battery cell;
step S2: acquiring a battery state;
when the battery is in a charged state, the process proceeds to step S3;
when the battery is in a discharged state, the process proceeds to step S4;
when the battery is in a resting state, keeping the SOC value unchanged;
step S3: setting a fixed limit M, and comparing the SOC value with the magnitude of M, wherein M is a fixed value and is 70% < M < 100%;
if the SOC value is more than 0 and less than M, the SOC value is still calculated by adopting an ampere-hour integration algorithm;
if the SOC value is equal to M, entering advanced calibration;
if the SOC value is more than M and less than 100%, calculating the SOC value by adopting a real-time voltage calibration method;
step S4: setting a fixed limit N, and comparing the SOC value with the N, wherein N is a fixed value and is 0% < N < M < 100%;
if the SOC value is more than N and less than 100%, the SOC value is still calculated by adopting an ampere-hour integration algorithm;
if the SOC value is equal to N, entering advanced calibration;
if the SOC value is more than 0 and less than N, the SOC value is calculated by adopting a real-time voltage calibration method.
Preferably, the advance calibration in step S3 includes the following steps:
polling the current temperature and the current charging current of all the battery cells, selecting an SOC-voltmeter suitable for the current temperature and the current charging current of the battery cells, and inquiring voltage Y when the SOC is equal to M as a calibration voltage value;
and comparing whether the current voltage of the battery core reaches Y, if so, calculating by using real-time voltage calibration to obtain an SOC value, and quickly fitting and displaying the SOC value as M to finish calibration.
Preferably, when the voltage value of the highest cell in all the cells is smaller than the current calibration voltage value Y, the charging is still required until the calibration voltage value Y is reached.
Preferably, the advance calibration in step S4 includes the following steps:
polling the current temperature and the current discharge current of all the battery cells, selecting an SOC-voltmeter suitable for the current temperature and the current discharge current of the battery cells, and inquiring voltage Z when the SOC is equal to N as a calibration voltage value; and comparing whether the current voltage of the battery core reaches Z, if so, calculating by using real-time voltage calibration to obtain an SOC value, and quickly fitting and displaying the SOC value as N to finish calibration.
Preferably, when the voltage value of the lowest cell in all the cells is greater than Z of the current calibration voltage value, the discharge is still required until Z of the calibration voltage value is reached.
Preferably, M in step S3 is 90% and N in step S4 is 10%.
Preferably, in steps S3 and S4, a coulombic efficiency coefficient k is obtained from the coulombic efficiency table based on the battery current and the temperature in the time period t, an ampere-hour integration algorithm is performed based on the coulombic efficiency coefficient k, and a formula for calculating the SOC value by the ampere-hour integration algorithm is as follows:
Figure BDA0002581579950000031
wherein the SOC0Is an initial SOC value, CNThe total capacity of the battery core is shown, and I is the current of the battery; η is the discharge efficiency, k is the coulombic efficiency coefficient, and t is the time period.
Preferably, in step S3, the real-time voltage calibration method is to poll the current temperature and the current charging current of the battery cell, select an SOC-voltmeter applicable to the current temperature and the current charging current of the battery cell, and obtain an SOC value according to the SOC corresponding to the current voltage;
in step S4, the real-time voltage calibration method is to poll the current temperature and the current discharge current of the battery cell, select an SOC-voltmeter applicable to the current temperature and the current discharge current of the battery cell, and obtain an SOC value according to the SOC corresponding to the current voltage.
Preferably, in step S3, when the SOC value calculated by the real-time voltage calibration method is 100%, the charging is stopped;
in step S4, when the SOC value is calculated to be 0% by the real-time voltage calibration method, the discharge is stopped.
According to the SOC calibration algorithm, a coulomb efficiency table is obtained according to test data of cell materials forming a battery at different temperatures and different currents, the total capacity of the battery is obtained according to the rated total capacity of the cell and the coulomb efficiency table, the SOC value is compared with a set fixed threshold value and then enters a voltage calibration state in advance, SOC deviation is prevented from reaching a charging end or a discharging end and then calibration is carried out, and the deviation rate of the SOC is reduced in advance; meanwhile, during later calibration, the used calibration voltage is obtained according to original data under different temperatures and different current conditions in the charging or discharging process, rather than adopting the value of open-circuit voltage (OCV), so that the accuracy of voltage calibration in the charging process and the discharging process is ensured.
In addition, compared with the existing algorithm, when the result obtained by the ampere-hour integral method and the voltage calibration has a difference value, the SOC mutation is easily generated, but the algorithm has the value that the SOC display value of the system can smoothly approach the real-time voltage calibration by calibration in advance, so that the use experience of a customer is improved while the accurate parameters are ensured.
In addition, the SOC calibration algorithm is high in accuracy, the SOC estimation error is less than 5%, the maintenance cost of the battery is reduced, and the use requirement of the BMS can be met.
Drawings
FIG. 1 is a flow chart of an SOC calibration algorithm of the present invention;
FIG. 2 is a graph showing the relationship between the SOC curve calculated by the present invention and the original data SOC curve (25 ℃, 0.3C, charging);
FIG. 3 is a graph of the SOC curves calculated by the present invention versus the original data SOC curves (25 deg.C, 0.3C, discharge).
Detailed Description
The following describes a specific embodiment of the SOC calibration algorithm according to the present invention with reference to the embodiment shown in fig. 1. An SOC calibration algorithm of the present invention is not limited to the description of the following embodiments.
An SOC calibration algorithm comprising the steps of,
step S1: obtaining a coulombic efficiency table according to test data of materials of the battery cell at different temperatures and different currents, obtaining a total capacity value of the battery cell by using the rated total capacity of the battery cell and the coulombic efficiency table, and obtaining and storing an SOC-voltmeter of the battery cell;
step S2: acquiring a battery state;
when the battery is in a charged state, the process proceeds to step S3;
when the battery is in a discharged state, the process proceeds to step S4;
when the battery is in a resting state, keeping the SOC value unchanged;
step S3: setting a fixed limit M, wherein M is a fixed value and 70% < M < 100%, and comparing the SOC value with the magnitude of M;
if the SOC value is more than 0 and less than M, the SOC value is still calculated by adopting an ampere-hour integration algorithm;
if the SOC value is equal to M, entering advanced calibration;
if the SOC value is more than M and less than 100%, calculating the SOC value by adopting a real-time voltage calibration method;
step S4: setting a fixed limit N, wherein N is a fixed value, 0% < N < M < 100%, and comparing the SOC value with the N;
if the SOC value is more than N and less than 100%, the SOC value is still calculated by adopting an ampere-hour integration algorithm;
if the SOC value is equal to N, entering advanced calibration;
if the SOC value is more than 0 and less than N, the SOC value is calculated by adopting a real-time voltage calibration method.
According to the SOC calibration algorithm, a coulomb efficiency table is obtained according to test data of cell materials forming a battery at different temperatures and different currents, the total capacity of a cell is obtained according to the rated total capacity of the cell and the coulomb efficiency table, and the SOC value is compared with a set fixed limit value to well enter a voltage calibration state in advance, so that the SOC deviation is prevented from reaching a charging end or a discharging end and then calibration is carried out, and the deviation rate of the SOC is reduced in advance; meanwhile, during later calibration, the used calibration voltage is obtained according to original data under different temperatures and different current conditions in the charging or discharging process, rather than adopting the value of open-circuit voltage (OCV), so that the accuracy of voltage calibration in the charging process and the discharging process is ensured.
In addition, compared with the existing algorithm, when the result obtained by the ampere-hour integral method and the voltage calibration has a difference value, the SOC mutation is easily generated, but the algorithm has the value that the SOC display value of the system can smoothly approach the real-time voltage calibration by calibration in advance, so that the use experience of a customer is improved while the accurate parameters are ensured.
Referring to fig. 1, a detailed description of an SOC calibration algorithm includes the following steps,
step S1: obtaining a coulombic efficiency table with corresponding coulombic efficiency coefficient k according to test data of materials of the battery cell at different temperatures and different currents, obtaining a total capacity value of a single battery cell based on rated total capacity Q of the battery cell and the coulombic efficiency coefficient k by using the coulombic efficiency table, wherein the coulombic efficiency table is shown in table 1, C is the multiplying power of the current magnitude during charging and discharging of the battery, for example, 63 ampere hours per unit ampere of the battery, 1C is 63A of the current, discharging is performed according to 0.3C multiplying power, and 0.3C is 18.9A (63 × 0.3 ═ 18.9):
multiplying power/temperature 0.3C 0.6C 1C 2C
0℃ 85.92％ 86.18％ 85.51％ 84.87％
10℃ 92.30％ 89.94％ 88.73％ 88.42％
25℃ 97.11％ 95.47％ 94.53％ 93.63％
35℃ 98.94％ 98.07％ 96.94％ 96.83％
45℃ 98.85％ 99.37％ 96.94％ 98.13％
TABLE 1 coulombic efficiency table
Therefore, the total capacity value of the battery in the algorithm refers to the actual available capacity value of the fully charged battery at different temperatures and currents, the product of the rated total capacity of the battery core and the coulomb efficiency value in table 1 is the total capacity value of the battery core at the corresponding temperature and current, and the SOC value is calculated by using a formula of battery core SOC which is the remaining capacity of the battery core/the total capacity of the battery core.
Step S2: acquiring a battery state;
when the battery is in a charged state, the process proceeds to step S3;
when the battery is in a discharged state, the process proceeds to step S4;
when the battery is in a resting state, keeping the SOC value unchanged; SOC value maintenance last time storage or calculationSOC (1)0The value is unchanged.
Step S3: firstly, determining an SOC limit M entering voltage calibration, wherein M is a fixed value and 70% < M < 100%, and preferably 90%, and comparing the SOC value with the magnitude of M;
if the SOC value is more than 0 and less than M, calculating the SOC value by adopting an ampere-hour integration algorithm;
if the SOC value is equal to M, entering advanced calibration;
if the SOC value is more than M and less than 100%, calculating the SOC value by adopting a real-time voltage calibration method.
The ampere-hour integration algorithm of the SOC value is as follows:
setting a period t, combining the accumulation of a charged battery current I in the period t and a charge capacity in the period t, or combining the accumulation of a discharged battery current I in the period t and a charge capacity in the period t, obtaining a coulombic efficiency coefficient k from a coulombic efficiency table based on the battery current and the temperature during the charging and discharging of the battery in the period t, and performing ampere-hour integration algorithm calculation based on the coulombic efficiency coefficient k, wherein an SOC value is a current capacity value/total battery cell capacity, and for example, a current SOC value calculation formula during discharging is as follows:
Figure BDA0002581579950000061
wherein the SOC0Is an initial SOC value, CNThe rated capacity of the battery core is shown, and I is the current of the battery; η is the discharge efficiency, k is the coulombic efficiency coefficient, and t is the time period.
Preferably, in the charging state, when the SOC value is M, current temperatures and current charging currents (hereinafter referred to as "duty") of all the battery cells are polled, an SOC-voltage table suitable for the duty is selected, and a voltage Y when the SOC value is M is queried as the calibration voltage value. And comparing whether the current voltage of the battery core reaches a calibration voltage value Y, if so, calculating by using real-time voltage calibration to obtain an SOC value, and quickly fitting and displaying the SOC value as M to finish calibration. If not, the ampere-hour integration method is continued to calculate the SOC. And when the SOC value is less than or equal to 100 percent and M is less than or equal to M, the SOC value is changed by adopting a real-time voltage calibration method. Wherein the SOC-calibration voltmeter under each working condition is obtained by testing in advance.
It should be noted that, because the ampere-hour integration method has an error, the voltage of the highest cell may not reach the calibration voltage value when the integrated SOC value reaches 90%, and in order to ensure the reliability of the SOC, it is determined that the SOC of the cell actually reaches 90% only when the voltage value of the highest cell reaches the calibration voltage value, and therefore, when the voltage value of the highest cell in all the cells is smaller than the calibration voltage value Y, charging is still required until the voltage value of the highest cell is equal to the calibration voltage value Y, so as to complete calibration. And when the SOC value is calculated to be 100% by adopting a real-time voltage calibration method, stopping charging.
When the SOC value is more than M and less than 100 percent, the real-time voltage calibration method comprises the following steps: polling the current temperature and the current charging current of the battery core, selecting an SOC-voltmeter suitable for the working condition, and obtaining an SOC value according to the SOC corresponding to the current voltage, wherein the SOC-voltmeter is test data of the battery and is known data.
Step S4: firstly, determining an SOC limit N entering voltage calibration, wherein N is a fixed value and 0% < N < M < 100%, preferably 10%, and comparing the SOC value with the N, and 0% < N < M < 100%;
if the SOC value is more than N and less than 100%, the SOC value is still calculated by adopting an ampere-hour integration algorithm;
if the SOC value is equal to N, entering advanced calibration;
if the SOC value is more than 0 and less than N, the SOC value is calculated by adopting a real-time voltage calibration method.
Preferably, in the charging state, when the SOC value is equal to N, the current temperatures and current charging currents (hereinafter referred to as "duty") of all the battery cells are polled, an SOC-voltage table suitable for the duty is selected, and the voltage Z when the SOC is equal to N is looked up as the calibration voltage value. And comparing whether the current voltage of the battery cell reaches Z, if so, calculating by using real-time voltage calibration to obtain an SOC value, quickly fitting and displaying the SOC value as N, and finishing calibration. If not, the ampere-hour integration method is continued to calculate the SOC. And when the SOC value is more than or equal to 0% and less than or equal to N, the SOC value is changed by adopting a real-time voltage calibration method.
It should be noted that, when the voltage value of the lowest cell in all the cells is greater than the current calibration voltage value Z, it is still necessary to perform discharging until the voltage of the lowest cell is equal to the current calibration voltage value Z, so as to complete calibration. When the SOC value is calculated to be 0% by adopting a real-time voltage calibration method, the discharging is stopped.
When the SOC value is more than 0 and less than N, the real-time voltage calibration method comprises the following steps: polling the current temperature and the current discharge current of the battery core, selecting an SOC-voltmeter applicable to the working condition, and obtaining an SOC value through the SOC corresponding to the current voltage, wherein the SOC-voltmeter is test data of the battery.
The SOC-voltmeter used in the real-time voltage calibration method is obtained according to the original data of the battery voltage values corresponding to the SOC values under different temperatures and different current conditions in the charging or discharging process.
The SOC precision verification method comprises the following steps:
taking the SOC accuracy calculated for the battery at 25 ℃ under the charge and discharge conditions of 0.3C as an example:
the rated total capacity of the battery core is Q, the battery is charged at a certain current value, an SOC value Q1 at the time of t1 is recorded, meanwhile, the charging capacity is calculated by ampere-hour integration, the charging is continued to the time of t2, an SOC value Q2 at the time of t2 is recorded, meanwhile, the charging capacity at the time of t2 is calculated by ampere-hour integration, k is a coulombic efficiency coefficient, 97.11 percent is taken, and an SOC error is calculated by the following formula (the SOC value corresponding to the time of t0 is 0 percent):
Figure BDA0002581579950000081
Figure BDA0002581579950000082
Figure BDA0002581579950000083
the test result shows that the SOC estimation error is less than or equal to 5 percent.
SOC curve: the calculated SOC curve versus the raw data SOC curve under the charging condition of 0.3C at 25C is shown in fig. 2.
SOC curve: the calculated SOC curve versus the raw data SOC curve under the discharge condition of 0.3C at 25C is shown in fig. 3.
By combining the calculated SOC curve and the original data SOC curve corresponding graph, the deviation of the SOC curve using the algorithm and the SOC curve of the original data is within 5%, and the BMS use requirement can be met.
An example of charging a battery at ambient temperature 25 ℃ is provided, the battery of this example being emptied first until the SOC value shows 0%, followed by the following steps:
step 1: charging the battery by using the current of 0.3C (18.9A), and changing the SOC value in the range of 0-90% by adopting an ampere-hour integration method;
step 2: polling the current and the current temperature of all the battery cells, inquiring an SOC-voltmeter to obtain a corresponding calibration voltage Y when the voltage of the highest monomer battery cell reaches the calibration voltage Y, and displaying 90% of the fitting of the SOC value when the voltage of the highest monomer battery cell reaches the calibration voltage Y to finish calibration;
and step 3: when the SOC value is between 90% and 100%, the SOC value is changed by adopting a real-time voltage calibration method, and when the SOC value is calculated to be 100% by adopting the real-time voltage calibration method, the charging is stopped.
There is provided an example of discharge of a battery at an ordinary temperature of 25 ℃, the battery of this example being charged first to show an SOC value of 100%, followed by the steps of:
step 1: the battery is discharged at the current of 0.3C (18.9), and the SOC value is changed in the range of 100-10% by adopting an ampere-hour integration method;
step 2: polling the current currents and the current temperatures of all the battery cells, inquiring an SOC-voltmeter to obtain a corresponding calibration voltage Z when the voltage of the lowest monomer battery cell reaches the calibration voltage Z, and displaying the SOC value by fitting 10% to finish calibration when the voltage of the lowest monomer battery cell reaches the calibration voltage Z;
and step 3: when the SOC value is 10% -0%, the SOC value is changed by adopting a real-time voltage calibration method, and when the SOC value is calculated to be 0% by adopting the real-time voltage calibration method, the discharging is stopped.
The SOC calibration method can be used for battery management systems of various electric energy storage systems with electric cores, is stored in a memory and is executed by a microprocessor MCU of the electric energy storage system. For example, the solar energy storage battery can be used for solar energy household energy storage batteries, electric vehicles and the like.
The foregoing is a more detailed description of the invention in connection with specific preferred embodiments and it is not intended that the invention be limited to these specific details. For those skilled in the art to which the invention pertains, several simple deductions or substitutions can be made without departing from the spirit of the invention, and all shall be considered as belonging to the protection scope of the invention.

Claims (9)

1. An SOC calibration algorithm, characterized by: comprises the following steps of (a) carrying out,
step S1: obtaining a coulombic efficiency table according to test data of materials of the battery cell at different temperatures and different currents, obtaining a total capacity value of the battery cell by using a rated total capacity value of the battery cell and the coulombic efficiency table, and obtaining and storing an SOC-voltmeter of the battery cell;
step S2: acquiring a battery state;
when the battery is in a charged state, the process proceeds to step S3;
when the battery is in a discharged state, the process proceeds to step S4;
when the battery is in a resting state, keeping the SOC value unchanged;
step S3: setting a fixed limit M, and comparing the SOC value with the magnitude of M, wherein M is a fixed value and is 70% < M < 100%;
if the SOC value is more than 0 and less than M, the SOC value is still calculated by adopting an ampere-hour integration algorithm;
if the SOC value is equal to M, entering advanced calibration;
if the SOC value is more than M and less than 100%, calculating the SOC value by adopting a real-time voltage calibration method;
step S4: setting a fixed limit N, and comparing the SOC value with the N, wherein N is a fixed value and is 0% < N < M < 100%;
if the SOC value is more than N and less than 100%, the SOC value is still calculated by adopting an ampere-hour integration algorithm;
if the SOC value is equal to N, entering advanced calibration;
if the SOC value is more than 0 and less than N, the SOC value is calculated by adopting a real-time voltage calibration method.
2. The SOC calibration algorithm of claim 1, wherein: the advance calibration in step S3 includes the steps of:
polling the current temperature and the current charging current of all the battery cells, selecting an SOC-voltmeter suitable for the current temperature and the current charging current of the battery cells, and inquiring voltage Y when the SOC is equal to M as a calibration voltage value;
and comparing whether the current voltage of the battery core reaches Y, if so, calculating by using real-time voltage calibration to obtain an SOC value, and quickly fitting and displaying the SOC value as M to finish calibration.
3. The SOC calibration algorithm of claim 2, wherein: when the voltage value of the highest monomer battery cell in all the battery cells is smaller than the current calibration voltage value Y, charging is still required until the calibration voltage value Y is reached.
4. The SOC calibration algorithm of claim 1, wherein: the advance calibration in step S4 includes the steps of:
polling the current temperature and the current discharge current of all the battery cells, selecting an SOC-voltmeter suitable for the current temperature and the current discharge current of the battery cells, and inquiring voltage Z when the SOC is equal to N as a calibration voltage value; and comparing whether the current voltage of the battery core reaches Z, if so, calculating by using real-time voltage calibration to obtain an SOC value, and quickly fitting and displaying the SOC value as N to finish calibration.
5. The SOC calibration algorithm of claim 4, wherein: when the voltage value of the lowest cell in all the cells is greater than Z of the current calibration voltage value, discharging is still required until Z of the calibration voltage value is reached.
6. The SOC calibration algorithm of claim 1, wherein: m in step S3 is 90%, and N in step S4 is 10%.
7. The SOC calibration algorithm of claim 1, wherein: in steps S3 and S4, a coulombic efficiency coefficient k is obtained from the coulombic efficiency table based on the battery current and the temperature within the time period t, an ampere-hour integration algorithm is calculated based on the coulombic efficiency coefficient k, and a formula for calculating the SOC value by the ampere-hour integration algorithm is as follows:
Figure FDA0002581579940000021
wherein the SOC0Is an initial SOC value, CNThe total capacity of the battery core is shown, and I is the current of the battery; η is the discharge efficiency, k is the coulombic efficiency coefficient, and t is the time period.
8. The SOC calibration algorithm of claim 1, wherein: in step S3, the real-time voltage calibration method is to poll the current temperature and the current charging current of the battery cell, select an SOC-voltmeter applicable to the current temperature and the current charging current of the battery cell, and obtain an SOC value according to the SOC corresponding to the current voltage;
in step S4, the real-time voltage calibration method is to poll the current temperature and the current discharge current of the battery cell, select an SOC-voltmeter applicable to the current temperature and the current discharge current of the battery cell, and obtain an SOC value according to the SOC corresponding to the current voltage.
9. The SOC calibration algorithm of claim 1, wherein: in the step S3, when the SOC value calculated by the real-time voltage calibration method is 100%, stopping charging;
in step S4, when the SOC value is calculated to be 0% by the real-time voltage calibration method, the discharge is stopped.
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Cited By (2)

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EP4372398A1 (en) * 2022-11-15 2024-05-22 Sungrow Power Supply Co., Ltd. Method and device for calibrating soc at tail end of charging or discharging of energy storage system
WO2024119645A1 (en) * 2022-12-07 2024-06-13 惠州亿纬锂能股份有限公司 Battery soc value estimation method, estimation apparatus, battery management system, and storage medium

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
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WO2024119645A1 (en) * 2022-12-07 2024-06-13 惠州亿纬锂能股份有限公司 Battery soc value estimation method, estimation apparatus, battery management system, and storage medium

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