CN110618389A - Method and device for testing battery SOC-OCV curve - Google Patents
Method and device for testing battery SOC-OCV curve Download PDFInfo
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- CN110618389A CN110618389A CN201910912498.1A CN201910912498A CN110618389A CN 110618389 A CN110618389 A CN 110618389A CN 201910912498 A CN201910912498 A CN 201910912498A CN 110618389 A CN110618389 A CN 110618389A
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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]
- G01R31/385—Arrangements for measuring battery or accumulator variables
- G01R31/387—Determining ampere-hour charge capacity or SoC
- G01R31/388—Determining ampere-hour charge capacity or SoC involving voltage measurements
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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]
- G01R31/389—Measuring internal impedance, internal conductance or related variables
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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]
- G01R31/396—Acquisition or processing of data for testing or for monitoring individual cells or groups of cells within a battery
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Abstract
The application discloses a method for testing a battery SOC-OCV curve. The testing method of the SOC-OCV curve of the battery comprises the following steps: charging the battery to an upper limit voltage at a constant current of 0.15-0.25C to obtain a first charging curve; wherein, the upper limit voltage refers to the voltage when the battery is fully charged; discharging the battery to a termination voltage by using a constant current to obtain a first discharge curve; wherein, the termination voltage refers to the lowest voltage when the battery discharges; and determining a test SOC-OCV curve of the battery at the first constant temperature according to the average value of the first charging curve and the first discharging curve. The test method of the SOC-OCV curve of the battery greatly saves the times that the battery needs to be stood, thereby saving the whole test time and improving the test efficiency. The application also discloses a device for testing the SOC-OCV curve of the battery, which can execute the testing method.
Description
Technical Field
The application relates to the technical field of batteries, in particular to a method and equipment for testing a battery SOC-OCV curve.
Background
The power battery is a device for converting chemical energy into electric energy, the conversion process is a complex physical and chemical reaction process, and the calculation of the available residual capacity of the power battery is of great significance for estimating the residual driving mileage of the electric automobile, avoiding the incapability of driving due to the fact that the automobile is out of power, charging the automobile in time and the like.
The state of charge (SOC) of a power battery is one of important parameters for characterizing the state of the battery, and is often used to reflect the available remaining capacity of the battery. Open Circuit Voltage (OCV) is the voltage across the battery in an open circuit state. The open circuit voltage is not affected by the charge and discharge current and is related to the battery material and the state of charge of the battery. Under a certain temperature, the state of charge of the battery and the open-circuit voltage are in one-to-one correspondence, so that the state of charge of the battery can be obtained by testing the open-circuit voltage according to an SOC-OCV curve, and the available residual capacity of the power battery is determined.
In the traditional process of testing the SOC-OCV curve at a single temperature point, because the voltage value of the next state of charge can be tested only by standing for a long time (usually more than 2 hours) after the last state of charge is tested when the voltages in any two states of charge are tested, the time consumed for testing one temperature point is more than 50 hours, the method for testing the SOC-OCV curve in the traditional technology has a long period and consumes the testing time.
Disclosure of Invention
The application provides a test method of a battery SOC-OCV curve, the test method does not need to test corresponding voltages under a plurality of charge states respectively, and the number of times of battery standing is reduced, so that standing time is greatly saved, the whole test time is saved, and the test efficiency is improved. The application also provides equipment for testing the SOC-OCV curve of the battery.
In a first aspect, the present application provides a method of testing a battery SOC-OCV curve. The testing method of the SOC-OCV curve of the battery comprises the following steps:
placing the battery in a first constant temperature environment;
charging the battery to an upper limit voltage at a constant current of 0.15-0.25C to obtain a first charging curve; the upper limit voltage refers to the voltage when the battery is fully charged, and the first charging curve represents the relationship between the state of charge of the battery and the corresponding voltage at two ends of the battery in the constant current charging process of the battery;
discharging the battery to a termination voltage by using the constant current to obtain a first discharge curve; the termination voltage refers to the lowest voltage of the battery during discharging, and the first discharging curve represents the relation between the state of charge of the battery and the voltage at two ends of the corresponding battery in the constant current discharging process of the battery; and
and determining a test SOC-OCV curve of the battery at the first constant temperature according to the average value of the first charging curve and the first discharging curve.
In one embodiment, before charging the battery to the upper limit voltage at a constant current, the test method further comprises:
charging the battery to the upper limit voltage at a current of 1C;
after the cell was left to stand for 1 to 4 hours, the cell was discharged to the end voltage with a current of 1C.
In one embodiment, after charging the battery to the upper limit voltage at a constant current of 0.15C to 0.25C and before discharging the battery to the termination voltage at the constant current, the test method further comprises:
the cell was left to stand for 1 to 4 hours.
In one embodiment, the number of cells is greater than or equal to 3, the testing method further comprising:
and confirming a standard SOC-OCV curve of the battery according to the average value of the test SOC-OCV curves of a plurality of batteries.
In one embodiment, the first constant temperature is greater than or equal to 0 degrees.
In one embodiment, after determining a test SOC-OCV curve for the battery at the first constant temperature, the testing method further comprises:
placing the battery in a second constant temperature environment, wherein the second constant temperature is different from the first constant temperature;
charging the battery to the upper limit voltage by using the constant current to obtain a second charging curve;
discharging the battery to the termination voltage by using the constant current to obtain a second discharge curve; and
and determining a test SOC-OCV curve of the battery at the second constant temperature according to the average value of the second charging curve and the second discharging curve.
In one embodiment, the second constant temperature is greater than or equal to 0 degrees.
In one embodiment, after determining a test SOC-OCV curve for the battery at the first constant temperature, the testing method further comprises:
placing the battery in a third constant temperature environment, wherein the third constant temperature is less than the first constant temperature, and the third constant temperature is less than 0 ℃;
discharging the battery to the termination voltage by using a constant current less than or equal to 0.05C, and acquiring the state of charge of the battery and the corresponding voltage at two ends of the battery in real time;
and determining a test SOC-OCV curve of the battery at the third constant temperature according to the relation between the state of charge of the battery and the corresponding voltages at the two ends of the battery.
In one embodiment, prior to placing the battery in the third constant temperature environment, the testing method further comprises:
charging the battery to the upper limit voltage.
In a second aspect, the present application also provides an apparatus for testing a battery SOC-OCV curve. The apparatus for testing a battery SOC-OCV curve comprises a processor for executing the testing method according to any one of claims 1 to 9.
In the embodiment of the application, on one hand, the SOC-OCV curve can be obtained by measuring each state of charge and the corresponding open-circuit voltage after the battery voltage tends to be stable without standing for a period of time at certain intervals, and the SOC-OCV curve can be obtained only according to the average value of the charging curve and the discharging curve, so that the testing procedure is greatly simplified.
On the other hand, the corresponding voltages under a plurality of charge states do not need to be tested respectively, so that the number of times of battery standing is reduced, the standing time is greatly saved, the whole testing time is saved, and the testing efficiency is improved.
In a third aspect, by using the testing method of the embodiment of the present application, since the obtained charging curve and the discharging curve are both a continuous curve, the SOC-OCV curve obtained according to the charging curve and the discharging curve is also a continuous curve, so that the accuracy of the state of charge can be significantly improved when checking and looking up the table at the start.
Drawings
In order to more clearly illustrate the technical solution of the present application, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative efforts.
FIG. 1 is a schematic flow chart of a method for testing a battery SOC-OCV curve provided herein in a first embodiment;
FIG. 2 is a graph showing test results obtained by the test method of FIG. 1;
FIG. 3 is a schematic flow chart of a method for testing a battery SOC-OCV curve provided herein in a second embodiment;
FIG. 4 is a schematic flow chart of S210 shown in FIG. 3;
FIG. 5 is a schematic flow chart of a method for testing a battery SOC-OCV curve provided herein in a third embodiment;
FIG. 6 is a schematic flow chart of a method for testing a battery SOC-OCV curve provided herein in a fourth embodiment;
fig. 7 is a schematic flow chart of a testing method of a battery SOC-OCV curve provided by the present application in a fifth embodiment;
fig. 8 is a schematic flow chart of a method for testing a battery SOC-OCV curve according to the sixth embodiment.
Detailed Description
Technical solutions in embodiments of the present application will be described below with reference to the drawings in the embodiments of the present application, and it is apparent that the described embodiments are only some embodiments of the present application, and not all embodiments. In the present invention, the embodiments and features of the embodiments may be combined with each other without conflict. All other embodiments obtained by a person of ordinary skill in the art without any inventive work based on the embodiments in the present application are within the scope of protection of the present application.
In the using process of the battery, the state of charge of the battery is an important index, namely the ratio of the electric quantity actually provided in the current state to the electric quantity provided by full charge, so that the residual electric quantity of the current state of the battery can be estimated according to the state of charge of the battery, and the current state of the battery can be conveniently estimated by a battery management system. The open circuit voltage is the terminal voltage of the battery in the open circuit state.
Generally, after a battery is placed for a long time after being charged or discharged, the polarization influence of the battery is eliminated, and the battery reaches a stable state. Under a certain temperature, the state of charge of the battery and the open-circuit voltage are in one-to-one correspondence, so that the SOC-OCV curve of the battery can be obtained according to the correspondence between the state of charge of the battery and the open-circuit voltage. The SOC of the battery can be obtained by testing the open-circuit voltage according to the SOC-OCV curve of the battery, so that the available residual capacity of the power battery can be determined.
Based on the problems that the test of the SOC-OCV curve of the battery at a single temperature point in the traditional technology needs to consume at least 50 hours and test time, the application provides the test method of the SOC-OCV curve of the battery, the test method can shorten the test time, and correspondingly shortens the test cost and labor cost. The method is applied to various types of batteries, such as lithium batteries, lead storage batteries, dry batteries, or the like. And the tested SOC-OCV curve is the SOC-OCV curve of the battery cell in the battery. The cell refers to a single electrochemical cell containing a positive electrode and a negative electrode. The cells are generally not directly usable, while the batteries are directly usable. After the battery core is provided with the shell and the protection circuit, the battery core can be directly used.
Referring to fig. 1 and fig. 2 together, fig. 1 is a schematic flow chart of a method for testing a battery SOC-OCV curve according to a first embodiment of the present disclosure; FIG. 2 is a graph showing the results of the test method shown in FIG. 1. The application provides a device and a method for testing a battery SOC-OCV curve. An apparatus for testing a battery SOC-OCV curve includes a processor. The processor is used for executing a test method of the battery SOC-OCV curve.
The test method of the SOC-OCV curve of the battery comprises the following steps:
s110: the battery is placed in a first constant temperature environment.
Because the corresponding relation between the state of charge and the open-circuit voltage of the battery is different at different temperatures due to different internal resistances of the battery at different temperatures, the battery is placed in a constant temperature environment, the test result caused by the temperature change of the battery is avoided, and the test accuracy is improved. Wherein, the battery can be placed in the thermostat to make the battery be in the constant temperature state.
In the embodiment of the present application, the first constant temperature is described as 25 degrees. In other embodiments, the first constant temperature can be other temperatures, e.g., 0 degrees, 10 degrees, 20 degrees, or the like.
S120: the battery is charged to an upper limit voltage at a constant current of 0.15C to 0.25C, resulting in a first charging curve.
It can be understood that the apparatus for testing the SOC-OCV curve of the battery charges the battery at a constant current of 0.15C to 0.25C and obtains a first charging curve. Wherein, the 1C current is the same current as the battery capacity, for example, when the battery capacity is 2000mAh, the 1C current is 2000 mA; when the battery capacity is 1000mAh, the 1C current is 1A. It is understood that 1C corresponds to a current value, the magnitude of which is related to the battery capacity. When the constant current is in the range of 0.15C to 0.25C, the generated current is small, so that the divided voltage caused by the internal resistance is small, and the polarization generated in the battery during the charging and discharging processes is small. For example, in one embodiment, the apparatus that tests the SOC-OCV curve of the battery charges the battery at a constant current of 0.2C and obtains a first charging curve.
In the embodiment of the application, the constant current is used for charging and discharging in the range of 0.15C to 0.25C, and the polarization of the battery generated in the discharging process of the charger is small, so that the test result is more accurate.
The upper limit voltage refers to the voltage when the battery is fully charged. It is understood that the upper limit voltage is the highest voltage of the battery. After the battery is shipped, the manufacturer gives the maximum voltage of the battery. The maximum voltage is not necessarily a fixed value, but may be a value within a certain range. The upper limit voltage is not a fixed value, and can be a value in a range close to the maximum voltage of the battery. Since the maximum voltage differs from battery to battery, the upper limit voltage may vary depending on the kind of battery.
The first charging curve represents a relationship between a state of charge of the battery and a voltage across the corresponding battery during constant current charging of the battery. It can be understood that, when the battery is charged with a constant current, the apparatus for testing the SOC-OCV curve of the battery acquires the state of charge of the battery during charging in real time and the voltage across the battery during charging. In the constant current charging process of the battery, each state of charge of the battery corresponds to one voltage value at two ends of the battery, and the equipment for testing the SOC-OCV curve of the battery can obtain a first charging curve according to the state of charge and the corresponding voltage at two ends of the battery. Therefore, in the embodiment of the present application, the charging curve is a continuous curve. It will be appreciated that the charging curve is not a curve interpolated from points.
S130: and discharging the battery to the termination voltage by using constant current to obtain a first discharge curve.
It can be understood that the apparatus for testing the SOC-OCV curve of the battery discharges the battery at a constant current of 0.15C to 0.25C, and obtains a first discharge curve. In one embodiment, the apparatus for testing the SOC-OCV curve of the battery discharges the battery at a constant current of 0.2C, and obtains a first discharge curve.
Wherein, the termination voltage refers to the lowest voltage when the battery is discharged. After the battery is shipped, the manufacturer gives the lowest voltage of the battery. The minimum voltage is not necessarily a fixed value, but may be a value within a certain range. The end voltage is not a fixed value and can be a range of values near the lowest voltage of the battery. Since the lowest voltage is different for different batteries, the termination voltage may vary according to the kind of battery.
The first discharge curve represents a relationship between a state of charge of the battery and a voltage across the corresponding battery during constant current discharge of the battery. It can be understood that the apparatus for testing the SOC-OCV curve of the battery acquires the state of charge of the battery in real time and the voltage across the battery during the discharge of the battery when the battery is discharged at a constant current. In the constant current discharging process of the battery, each state of charge of the battery corresponds to one voltage value at two ends of the battery, and the equipment for testing the SOC-OCV curve of the battery can obtain a first discharging curve according to the state of charge and the corresponding voltage at two ends of the battery. Therefore, in the embodiment of the present application, the discharge curve is a continuous curve. It will be appreciated that the discharge curve is not a curve interpolated from points.
S140: and determining a test SOC-OCV curve of the battery at the first constant temperature according to the average value of the first charging curve and the first discharging curve.
As shown in fig. 2, the abscissa represents the state of charge of the battery, and the ordinate represents the voltage across the battery. In the constant current charging process of the battery, under the same charge state, the voltage at two ends of the battery is greater than the open-circuit voltage during charging. In the constant current discharging process of the battery, under the same charge state, the voltage at two ends of the battery is smaller than the open-circuit voltage during discharging. Because the polarization of the battery in the charging and discharging processes is opposite, the polarization of the battery in the charging and discharging processes can be offset by solving the average value of the voltages at the two ends of the battery in the charging process and the voltages at the two ends of the battery in the discharging process, so that the accurate open-circuit voltage is obtained.
In the embodiment of the application, the SOC-OCV curve is equal to the average value of the first charging curve and the first discharging curve, so that the polarization of the battery in the charging process and the polarization of the battery in the discharging process are mutually eliminated, and the accurate open-circuit voltage is obtained. It will be appreciated that in the same state of charge, the open circuit voltage is equal to the average of the voltage across the battery when the battery is charged and the voltage across the battery when the battery is discharged.
On one hand, by adopting the testing method of the embodiment of the application, the SOC-OCV curve can be obtained by measuring each state of charge and the corresponding open-circuit voltage after the voltage region of the battery is stabilized without keeping the state of charge for a period of time at certain intervals, and the SOC-OCV curve can be obtained only according to the average value of the charging curve and the discharging curve, so that the testing procedure is greatly simplified.
In a second aspect, by using the test method of the embodiment of the present application, since the voltage is measured without standing for a period of time every certain interval of the state of charge, the standing time is greatly saved, thereby saving the whole test time and improving the test efficiency. For example, when the time consumed for charging and discharging the battery at a constant current of 0.2C to obtain the SOC-OCV curve is only about 12 hours, the test time is greatly saved compared with the time consumed in the prior art which is 50 hours.
In a third aspect, by using the testing method of the embodiment of the application, since the obtained charging curve and discharging curve are both a continuous curve and are complete SOC-OCV curves, the accuracy of the state of charge can be significantly improved when checking and looking up the table at startup.
The method for testing the SOC-OCV curve of the battery according to the first embodiment of the present application can test the SOC-OCV curve of the battery at the first constant temperature by using the testing method provided in the first embodiment of the present application after testing the SOC-OCV curve of the battery at the other temperature different from the first constant temperature by using the prior art. That is, when testing the SOC-OCV curves at different temperatures, the testing method provided by the embodiment of the present application can be used together with the testing method of the prior art, and can also be used to test the SOC-OCV curves of the battery at different temperatures only by using the testing method of the present application.
In the embodiment of the application, the battery is charged by using a constant current to obtain a charging curve, then the battery is discharged to obtain a discharging curve, and finally the battery SOC-OCV curve in the first constant temperature is determined according to the average value of the first charging curve and the first discharging curve. In other embodiments, the battery may be discharged at a constant current to obtain a discharge curve, then the battery is charged to obtain a charge curve, and finally the SOC-OCV curve of the battery at the first constant temperature is determined according to an average value of the first charge curve and the first discharge curve.
Further, the number of cells is greater than or equal to 3. The apparatus for testing the SOC-OCV curves of the battery determines a standard SOC-OCV curve of the battery based on an average value of the SOC-OCV curves of a plurality of batteries. It can be understood that the standard SOC-OCV curve of the battery is determined by the average value of the SOC-OCV curves of the plurality of batteries, which is the SOC-OCV curve of the final use of the battery tested at the first constant temperature.
In the embodiment of the application, because the number of the 1 battery samples is too small, and the number of the multiple battery samples is tested simultaneously, accidental errors can be avoided, and the test accuracy of the SOC-OCV curve is improved.
Wherein, in one embodiment, the apparatus for testing the SOC-OCV curves of the batteries simultaneously tests the test SOC-OCV curves of the plurality of batteries. And simultaneously testing SOC-OCV curves of a plurality of batteries to improve the testing efficiency and save the testing time.
Further, the first constant temperature is greater than or equal to 0 degrees.
In the embodiment of the application, the higher the temperature of the battery is, the higher the internal resistance of the battery is, and the more obvious the polarization phenomenon of the battery in the discharging and charging processes is, so that by adopting the method provided by the embodiment of the application, the SOC-OCV curve when the temperature is above 0 ℃ can be tested, and the testing accuracy can be improved.
Further, referring to fig. 3, fig. 3 is a schematic flow chart of a method for testing a battery SOC-OCV curve according to a second embodiment of the present application. Differences between the present embodiment and the first embodiment will be mainly described below, and most technical contents of the present embodiment that are the same as those of the first embodiment will not be described below.
The test method of the SOC-OCV curve of the battery comprises the following steps:
s210: the battery is activated.
The method for activating the battery can be that the battery is fully charged at a certain current and then the battery is discharged. That is, the battery is activated for one cycle of charging and discharging the battery.
The manner of activating the battery is not limited in the second embodiment. For example, the current for activating the battery and the time for standing between charging and discharging are not particularly limited in the second embodiment.
S220: the battery is placed in a first constant temperature environment.
The specific steps included in S220 are referred to as S110.
S230: the battery is charged to an upper limit voltage at a constant current of 0.15C to 0.25C, resulting in a first charging curve.
The specific steps included in S230 are referred to as S120.
S240: and discharging the battery to the termination voltage by using constant current to obtain a first discharge curve.
The specific steps included in S240 are referred to as S130.
S250: and determining the SOC-OCV curve of the battery at the first constant temperature according to the average value of the first charging curve and the first discharging curve.
The specific steps included in S250 are referred to in S140.
It is understood that before charging the battery to the upper voltage limit at a constant current, the test method further comprises: the battery is activated. Wherein activating the battery can be before placing the battery in the first constant temperature environment and can also be after placing the battery in the first constant temperature environment. In the present embodiment, description is made taking the case where the battery is activated at room temperature as an example.
In the embodiment of the application, before testing the SOC-OCV curve, the battery is activated, so that the accuracy of testing the SOC-OCV curve can be improved. Among them, the second embodiment of the present application provides a method of testing a battery SOC-OCV curve, which is capable of testing an unused battery.
Further, referring to fig. 4, fig. 4 is a flowchart illustrating the process of S210 shown in fig. 3, where the process of activating the battery includes:
s211: the battery was charged to the upper limit voltage with a current of 1C.
S212: after the cell was left to stand for 1 to 4 hours, the cell was discharged to an end voltage with a current of 1C.
In one embodiment, the battery is activated by cycling the battery with two 1C current cycles.
In the embodiment of the application, the method for activating the battery by national standard regulation can improve the stability of the battery and is beneficial to the accuracy of the SOC-OCV curve test.
Further, referring to fig. 5, fig. 5 is a schematic flow chart of a method for testing a battery SOC-OCV curve according to a third embodiment of the present application. Differences between the present embodiment and the foregoing embodiment will be mainly described below, and most technical contents of the present embodiment that are the same as those of the foregoing embodiment will not be described below.
The test method of the SOC-OCV curve of the battery comprises the following steps:
s310: the battery is placed in a first constant temperature environment.
The specific steps included in S310 are referred to as S110.
S320: the battery is charged to an upper limit voltage at a constant current of 0.15C to 0.25C, resulting in a first charging curve.
The specific steps included in S320 are referred to as S120.
S330: the cell was left to stand for 1 to 4 hours.
After the cell was left to stand for 1 to 4 hours, the cell voltage was stabilized so that the voltage across the cell was equal to the open circuit voltage. In one embodiment, the cell is left for 2 hours. In the present embodiment, the battery is left standing for 1 to 4 hours, and in other embodiments, the battery can also be left standing for four hours or more, for example, 5 hours.
S340: and discharging the battery to the termination voltage by using constant current to obtain a first discharge curve.
The specific steps included in S340 are referred to as S130.
S350: and determining a test SOC-OCV curve of the battery at the first constant temperature according to the average value of the first charging curve and the first discharging curve.
The specific steps included in S350 are referred to as S140.
In the embodiment of the application, before the battery is discharged to the termination voltage at the constant current and after the battery is charged to the upper limit voltage at the constant current, the battery is kept still for a period of time, so that the voltage of the battery is stable and tends to the open-circuit voltage, and the tested SOC-OCV curve is more accurate.
Further, referring to fig. 6, fig. 6 is a schematic flow chart of a method for testing a battery SOC-OCV curve according to a fourth embodiment of the present disclosure. Differences between the present embodiment and the foregoing embodiment will be mainly described below, and most technical contents of the present embodiment that are the same as those of the foregoing embodiment will not be described below.
S410: the battery is placed in a first constant temperature environment.
The specific steps included in S410 are referred to as S110.
S420: the battery is charged to an upper limit voltage at a constant current of 0.15C to 0.25C, resulting in a first charging curve.
The specific steps included in S420 are referred to as S120.
S430: and discharging the battery to the termination voltage by using constant current to obtain a first discharge curve.
The specific steps included in S430 are referred to as S130.
S440: and determining a test SOC-OCV curve of the battery at a first constant temperature according to the average value of the first charging curve and the first discharging curve.
The specific steps included in S440 are referred to as S140.
S450: the battery is placed in a second constant temperature environment, wherein the second constant temperature is different from the first constant temperature.
As can be appreciated, after determining the battery SOC-OCV curve at the first constant temperature, continuing to test the battery SOC-OCV curve at a second constant temperature different from the first constant temperature requires placing the battery in the constant temperature environment to be tested. The user can change the constant temperature environment in which the battery is located by adjusting the temperature of the incubator.
S460: and charging the battery to the upper limit voltage by using the constant current to obtain a second charging curve.
The specific steps included in S460 are referred to as S120.
It can be understood that when the battery is located in the second constant temperature environment, the battery is charged to the upper limit voltage at a constant current of 0.15C to 0.25C, resulting in a second charging curve. That is, the step of obtaining the second charging profile is the same as the step of obtaining the first charging profile, except that the battery is located in a different constant temperature environment.
S470: and discharging the battery to the final voltage by using constant current to obtain a second discharge curve.
The specific steps included in S470 are referred to as S130.
It is understood that when the battery is in the second constant temperature environment, the battery is discharged to the end voltage at a constant current of 0.15C to 0.25C, resulting in a second discharge curve. That is, the step of obtaining the second discharge curve is the same as the step of obtaining the first discharge curve, except that the battery is located in a different constant temperature environment.
S480: and determining the test SOC-OCV curve of the battery at the second constant temperature according to the average value of the second charging curve and the second discharging curve.
The specific steps included in S480 are as described in S140.
It is understood that when the battery is at the first constant temperature, the battery is charged to the upper limit voltage at the first constant current, resulting in the SOC-OCV curve at the first constant temperature. When the battery is at the second constant temperature, the battery is charged and discharged at the second constant current, and the SOC-OCV curve at the second constant temperature is obtained. Wherein the first constant temperature is different from the second constant temperature, the SOC-OCV curve at the first constant temperature is different from the SOC-OCV curve at the second constant temperature.
In the embodiment of the present application, the SOC-OCV curves of the battery at different temperatures can be tested by this method. After testing the SOC-OCV curve at one temperature, the constant temperature environment of the battery is directly changed without activating the battery again, and the battery is charged and discharged at constant current to determine the SOC-OCV curves at different temperatures.
In one embodiment, the second constant temperature is greater than or equal to 0 degrees. That is, in the present embodiment, both the first constant temperature and the second constant temperature are greater than or equal to 0 degrees. That is, the same manner may be adopted when testing the SOC-OCV curve of the battery at 0 degree or more. The second constant temperature can be greater than the first constant temperature and can also be less than the first constant temperature. For example, when the first constant temperature is 25 degrees, the second constant temperature can be 10 degrees, or 0 degrees, or 40 degrees.
Further, referring to fig. 7, fig. 7 is a schematic flow chart of a method for testing a battery SOC-OCV curve according to a fifth embodiment of the present disclosure. Differences between the present embodiment and the foregoing embodiment will be mainly described below, and most technical contents of the present embodiment that are the same as those of the foregoing embodiment will not be described below.
The test method of the SOC-OCV curve of the battery comprises the following steps:
s510: the battery is placed in a first constant temperature environment.
The specific steps included in S510 refer to S110.
S520: the battery is charged to an upper limit voltage at a constant current of 0.15C to 0.25C, resulting in a first charging curve.
The specific steps included in S520 are as described in S120.
S530: and discharging the battery to the termination voltage by using constant current to obtain a first discharge curve.
The specific steps included in S530 are referred to as S130.
S540: and determining a test SOC-OCV curve of the battery at the first constant temperature according to the average value of the first charging curve and the first discharging curve.
The specific steps included in S540 are referred to as S140.
S550: and placing the battery in a third constant temperature environment, wherein the third constant temperature is less than the first constant temperature, and the third constant temperature is less than 0 ℃.
As can be appreciated, after determining the battery SOC-OCV curve at the first constant temperature, continuing to test the battery SOC-OCV curve at a third constant temperature different from the first constant temperature requires placing the battery in the constant temperature environment to be tested. The user can change the constant temperature environment in which the battery is located by adjusting the temperature of the incubator. Wherein the third constant temperature is less than the first constant temperature, and the third constant temperature is less than 0 ℃. For example, when the first constant temperature is 25 degrees, 10 degrees, or 40 degrees, etc., the second constant temperature can be-10 degrees, -5 degrees, or-20 degrees, etc.
S560: discharging the battery to the end voltage by constant current less than or equal to 0.05C, and acquiring the charge state of the battery and the voltage at two ends of the corresponding battery in real time.
It is understood that when the SOC-OCV curve at the third constant temperature at which the temperature is less than 0 degree is tested, the current for charging the battery is small and is less than or equal to 0.05C. The cell is discharged to an end voltage, for example, with a constant current of 1/30C. Because the third constant temperature is less than the first constant temperature, the internal resistance of the battery in the third constant temperature state is greater than that of the battery in the first constant temperature state, and at the moment, a very small current is adopted, so that the polarization phenomenon of the battery can be reduced, the charge-discharge curve is closer to a real SOC-OCV curve, and the accuracy of the SOC-OCV curve at low temperature is improved.
S570: and determining a test SOC-OCV curve of the battery at a third constant temperature according to the relation between the state of charge of the battery and the voltage at two ends of the corresponding battery.
It is understood that when the SOC-OCV curve at a temperature less than 0 degree is tested, the battery is discharged to the end voltage at a constant current less than or equal to 0.05C, resulting in a discharge curve that is approximately equal to the battery SOC-OCV curve at the third constant temperature. Since, when testing the SOC-OCV curve at a temperature less than 0 degrees, only one discharge of low current is required, the test time can be saved.
In the present embodiment, a method of obtaining an SOC-OCV curve using an average value of a charge curve and a discharge curve when testing an SOC-OCV curve at a temperature greater than or equal to 0 degrees; when testing the SOC-OCV curve with the temperature less than 0 degree, the method that the discharge curve is approximately equal to the SOC-OCV curve when discharging at low current is adopted, so that the speed of the SOC-OCV curve with the temperature less than 0 degree is improved, and the accuracy of the SOC-OCV curve with the temperature less than 0 degree is also improved.
Further, referring to fig. 8, fig. 8 is a schematic flow chart of a method for testing a battery SOC-OCV curve according to a sixth embodiment of the present application. Differences between the present embodiment and the foregoing embodiment will be mainly described below, and most technical contents of the present embodiment that are the same as those of the foregoing embodiment will not be described below.
The test method of the SOC-OCV curve of the battery comprises the following steps:
s610: the battery is charged to an upper limit voltage.
Wherein, in one embodiment, the battery is charged to the upper limit voltage at normal temperature. The upper limit voltage refers to the voltage when the battery is fully charged. That is, when the test temperature is less than 0 degree SOC-OCV curve, the battery needs to be discharged with a small current under the condition that the battery is fully charged, so as to obtain the SOC-OCV curve at the corresponding temperature, and the integrity of the SOC-OCV curve can be ensured.
S620: placing the battery in a fourth constant temperature environment, wherein the fourth constant temperature is less than or equal to 0 ℃;
the specific steps included in S620 are referred to as S550. It is understood that the SOC-OCV curve of the test cell at a temperature of less than or equal to 0 degrees is now tested.
S630: discharging the battery to the end voltage by constant current less than or equal to 0.05C, and acquiring the charge state of the battery and the voltage at two ends of the corresponding battery in real time.
The specific steps included in S630 are referred to as S560.
S640: and determining a test SOC-OCV curve of the battery at a fourth constant temperature according to the relation between the state of charge of the battery and the voltage at the two ends of the corresponding battery.
The specific steps included in S640 are referred to as S570.
In the embodiment of the application, when the testing temperature is less than 0 degree of the SOC-OCV curve, the battery is discharged with small current under the condition that the battery is fully charged, so that the SOC-OCV curve at the corresponding temperature is obtained, and the integrity of the SOC-OCV curve can be guaranteed.
Wherein, in one embodiment, the battery is charged and fully charged at a constant current of 0.2C at room temperature.
The foregoing detailed description of the embodiments of the present application has been presented to illustrate the principles and implementations of the present application, and the above description of the embodiments is only provided to help understand the methods and their core ideas of the present application; meanwhile, for a person skilled in the art, according to the idea of the present application, there may be variations in the specific embodiments and application scope, and in summary, the content of the present specification should not be construed as a limitation to the present application.
Claims (10)
1. A method for testing a battery SOC-OCV curve, comprising:
placing the battery in a first constant temperature environment;
charging the battery to an upper limit voltage at a constant current of 0.15-0.25C to obtain a first charging curve; the upper limit voltage refers to the voltage when the battery is fully charged, and the first charging curve represents the relationship between the state of charge of the battery and the corresponding voltage at two ends of the battery in the constant current charging process of the battery;
discharging the battery to a termination voltage by using the constant current to obtain a first discharge curve; the termination voltage refers to the lowest voltage of the battery during discharging, and the first discharging curve represents the relation between the state of charge of the battery and the voltage at two ends of the corresponding battery in the constant current discharging process of the battery; and
and determining a test SOC-OCV curve of the battery at the first constant temperature according to the average value of the first charging curve and the first discharging curve.
2. The test method of claim 1, wherein prior to charging the battery to the upper voltage limit at a constant current of 0.15C to 0.25C, the test method further comprises:
charging the battery to the upper limit voltage at a current of 1C;
after the cell was left to stand for 1 to 4 hours, the cell was discharged to the end voltage with a current of 1C.
3. The test method of claim 1, wherein after charging a battery to the upper voltage limit at a constant current of 0.15C to 0.25C, and before discharging the battery to the terminal voltage at the constant current, the test method further comprises:
the cell was left to stand for 1 to 4 hours.
4. The test method of claim 1, wherein the number of cells is greater than or equal to 3, the test method further comprising:
and confirming a standard SOC-OCV curve of the battery according to the average value of the test SOC-OCV curves of a plurality of batteries.
5. The test method of claim 1, wherein the first constant temperature is greater than or equal to 0 degrees.
6. The test method of any one of claims 1 to 5, wherein after determining the test SOC-OCV curve for the battery at the first constant temperature, the test method further comprises:
placing the battery in a second constant temperature environment, wherein the second constant temperature is different from the first constant temperature;
charging the battery to the upper limit voltage by using the constant current to obtain a second charging curve;
discharging the battery to the termination voltage by using the constant current to obtain a second discharge curve; and
and determining a test SOC-OCV curve of the battery at the second constant temperature according to the average value of the second charging curve and the second discharging curve.
7. The test method of claim 6, wherein the second constant temperature is greater than or equal to 0 degrees.
8. The test method according to any one of claims 1 to 5, wherein after determining the test SOC-OCV curve of the battery at the first constant temperature, the test method further comprises:
placing the battery in a third constant temperature environment, wherein the third constant temperature is less than the first constant temperature, and the third constant temperature is less than 0 ℃;
discharging the battery to the termination voltage by using a constant current less than or equal to 0.05C, and acquiring the state of charge of the battery and the corresponding voltage at two ends of the battery in real time;
and determining a test SOC-OCV curve of the battery at the third constant temperature according to the relation between the state of charge of the battery and the corresponding voltages at the two ends of the battery.
9. The testing method of claim 8, wherein prior to placing the battery in a third constant temperature environment, the testing method further comprises:
charging the battery to the upper limit voltage.
10. An apparatus for testing a battery SOC-OCV curve, comprising a processor for performing the testing method according to any one of claims 1-9.
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