CN111426971A - Method and device for measuring battery internal resistance component - Google Patents
Method and device for measuring battery internal resistance component Download PDFInfo
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- CN111426971A CN111426971A CN202010289426.9A CN202010289426A CN111426971A CN 111426971 A CN111426971 A CN 111426971A CN 202010289426 A CN202010289426 A CN 202010289426A CN 111426971 A CN111426971 A CN 111426971A
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- G01R31/389—Measuring internal impedance, internal conductance or related variables
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- G—PHYSICS
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- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/36—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
- G01R31/378—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC] specially adapted for the type of battery or accumulator
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Abstract
The invention provides a method for measuring battery internal resistance component, which comprises the following steps: updating battery capacity data; charging or discharging the battery for a short time, standing for a certain time, and recording the instantaneous voltage jump delta U at the initial standing time1And a slow voltage change Δ U2And further acquiring the direct current internal resistance of the battery: r1＝ΔU1/ΔI，R2＝ΔU2A,/Δ I, wherein R1Comprising an ohmic internal resistance and an interfacial charge transfer internal resistance, R2Representing the concentration polarization internal resistance of the battery under the condition, wherein delta I is charging or discharging current; testing the alternating current internal resistance of the battery after standing to obtain the resistance value R representing the ohmic internal resistance of the battery0Further obtaining the electrochemical polarization internal resistance R of the batteryct＝R1‑R0. The invention also provides a corresponding device for realizing the method. The method and the device for measuring the internal resistance component of the battery have simple scheme implementation and are used for measuring electricityThe accuracy of the internal resistance of the battery is better, and each component of the internal resistance of the battery can be better identified, so that a basis is provided for analyzing the health state of the battery.
Description
Technical Field
The invention belongs to the technical field of lithium ion batteries, and particularly relates to a method and a device for measuring battery internal resistance components.
Background
Lithium ion battery internal resistance is a key parameter affecting battery power output performance. Due to the voltage drop of the ohmic internal resistance of the battery and the existence of polarization overpotential, the charging and discharging curve of the battery deviates from the open-circuit voltage curve of the batteryResulting in a decrease in the total output energy. At present, in the main research on the direct current internal resistance of the battery, in the aspect of detection and identification of ohmic internal resistance components, the variation trend of the ohmic internal resistance components along with the cyclic aging process of the battery is researched and is used as a characteristic parameter for representing the SOH of the battery. The internal resistance components of the cell correspond to different electrochemical processes, as shown in FIG. 1, wherein RoIndicating the ohmic internal resistance, RctFor electrochemical polarization internal resistance, R, caused by interfacial charge transferdThe impedance caused by ion diffusion (the electrochemical impedance spectrum of the cell is shown in figure 2). The processes have different time constants and reaction rates, and the research on the parameter identification method of each component and the variation trend of the parameters along with the working conditions has important significance for analyzing the degradation mechanism of the battery performance.
The direct current pulse method is a commonly used electrochemical test method for testing the internal resistance of a battery system. The principle of testing the internal resistance of the battery by the direct current pulse method is to apply larger current to a battery system in a stable state for a shorter time and analyze the voltage change of the battery in the process. The pulse current can cause the terminal voltage of the battery to change instantly, so that the ohmic internal resistance of the battery can be calculated through the process, then the current is kept unchanged, the polarization begins to appear in the battery, the voltage also changes gradually, and the equivalent circuit is shown as 3 (a). As shown in FIG. 3(b), t1To t2Time period, battery pulse discharge, t2When the clock pulse current is removed, the battery voltage changes instantaneously, and the change size is delta U1This stage is mainly due to the ohmic internal resistance of the battery. Then the battery voltage changes to Δ U2And gradually becomes larger, which represents the role of polarization internal resistance of the battery. By analyzing the change of the pulse discharge voltage of the battery at different stages, the information of various internal resistances of the battery can be obtained.
Although the direct current pulse method can be used for testing each internal resistance component of the lithium ion battery, in the actual measurement, the charge transfer speed of an SEI (solid electrolyte interface) and a solid-liquid interface on the internal interface of the battery, especially at the ionic/electronic conductive joint is very high, and the time constant is only dozens of ms. In the pulse battery test, the sampling frequency of the instrument does not exceed 10HZ, namely the sampling interval is not less than 100 ms. In the sampling time interval, the polarization voltage corresponding to the electrochemical polarization process is attenuated to be negligible, so that the charge transfer internal resistance is difficult to separate from the ohmic internal resistance in the test, and therefore, the resistance calculated by the sudden change voltage in the direct current pulse method test generally consists of the ohmic internal resistance and the charge transfer internal resistance. As shown in fig. 4, the resistance test is not accurate enough, and it needs to be combined with an ac battery internal resistance tester or electrochemical impedance spectroscopy to test the internal resistance of each part of the battery more accurately.
Disclosure of Invention
The invention aims to provide a method and a device for measuring the internal resistance component of a battery, so that the internal resistance of the battery is more accurate and convenient to test.
A first aspect of the present invention provides a method for measuring a component of an internal resistance of a battery, including the steps of:
s1, updating the battery capacity data;
s2, charging or discharging the battery for a short time, standing for a plurality of times, and recording the transient voltage jump delta U at the initial standing time1And a slow voltage change Δ U2And further acquiring the direct current internal resistance of the battery:
R1＝ΔU1/ΔI
R2＝ΔU2/ΔI
wherein R is1Comprising an ohmic internal resistance and an interfacial charge transfer internal resistance, R2Representing the concentration polarization internal resistance of the battery under the condition, wherein delta I is charging or discharging current;
s3, carrying out alternating current internal resistance test on the battery after standing to obtain resistance R representing ohmic internal resistance of the battery0Further obtaining the electrochemical polarization internal resistance R of the batteryct＝R1-R0。
Further, step S1 specifically includes:
firstly, the battery is charged to a full-charge state by adopting a CCCV charging method, and then the battery is discharged to a cut-off voltage by adopting the CCCV, wherein the cut-off current in the CV charging/discharging stage is not more than 1/20 rated capacity, or the battery is directly discharged to the cut-off voltage by adopting a current not more than 1/20C, and the capacity value at the moment is recorded as new C.
Further, in step S2, when the battery is charged or discharged for a short time, the applied current is not less than 1/5C, and the SOC of the battery is within a range of 10% to 90% after the discharge is completed.
Further, in step S2, the standing time is 10min or more.
A second aspect of the present invention provides a battery internal resistance component measuring device, including:
the charge and discharge controller is connected with the series battery pack and is used for carrying out direct current charge and discharge on the series battery pack;
the alternating current internal resistance tester is used for outputting small-amplitude alternating current to the monocells in the series battery pack and acquiring the internal resistance of the battery by detecting the voltage response of the battery;
the two analog switch groups are used for controlling the connection of the alternating current internal resistance tester and a certain single cell;
the data acquisition device or the battery management unit is respectively connected with the charge-discharge controller and the analog switch group and is used for controlling the action of the analog switch group and acquiring and recording the terminal voltage and the circuit current of each single battery in the charge-discharge process;
and the upper computer is in communication connection with the data acquisition device/battery management unit, the charge-discharge controller and the alternating current internal resistance tester and is used for controlling the operation of each device and receiving and processing data acquired by each device.
Furthermore, the test sampling frequency of the data acquisition device is 1HZ-20 HZ.
Further, the battery management unit is also used for equalizing charge of each single battery in the series battery pack so as to reduce SOC difference when charging is cut off among batteries.
Further, the alternating current internal resistance tester outputs 1KHZ alternating current with small amplitude.
The invention has the following beneficial technical effects:
the method and the device for measuring the battery internal resistance component have simple implementation scheme, have better accuracy in measuring the battery internal resistance, and can better identify each component of the battery internal resistance, thereby providing a basis for analyzing the health state of the battery.
Drawings
Fig. 1 is a schematic diagram illustrating the influence of the internal degradation mechanism of the battery due to the increase of the resistance.
FIG. 2 shows the results of electrochemical impedance spectroscopy.
FIG. 3 is a schematic diagram of an equivalent circuit and voltage/current variation of the DC pulse testing method.
FIG. 4 is a graph showing the comparison between the pulse current test results and the EIS results.
Fig. 5 is a schematic diagram of the system composition of the measuring device of the present invention.
FIG. 6 is a schematic circuit diagram of a measuring apparatus according to an embodiment of the present invention.
Fig. 7 is a schematic diagram comparing the ohmic internal resistances of the battery measured by the measuring device of the present invention and the EIS method.
FIG. 8 is a schematic diagram showing the comparison of electrochemical polarization internal resistance of the cell measured by the measurement device of the present invention and the EIS method.
Detailed Description
For a further understanding of the invention, reference will now be made to the preferred embodiments of the invention by way of example, and it is to be understood that the description is intended to further illustrate features and advantages of the invention, and not to limit the scope of the claims.
Example 1
A first embodiment of the present invention provides a method for measuring a component of an internal resistance of a battery, including the steps of:
1. the battery capacity data is updated to avoid the influence of the difference in C-rates on the test results, and the battery CCCV charging method may be first charged to a full state, and then the CCCV is discharged to a cut-off voltage. Wherein the cut-off current in the CV charging/discharging stage is not more than 1/20 rated capacity, or directly discharging to cut-off voltage at 1/20C, and recording the capacity value at the moment as new C. Charging or discharging the battery for a short time, keeping the SOC of the battery within a range of 10% -90% after the discharging is finished, standing for no less than 10 minutes, and generally enabling the discharging current to be no less than 1/5C.
Alternatively, in the case of unknown battery capacity, it can also be measured by:
1. and (3) carrying out constant current charging for 12min by using the current I, carrying out constant current discharging for 6min after standing for 15min, and simultaneously setting the upper limit of the battery voltage as a control condition in the constant current charging process so as to avoid overcharging.
2. Recording the instantaneous voltage jump delta U of the initial moment of the last standing of the battery1And a slow voltage change Δ U2In this embodiment, the voltage sampling frequency is 10HZ, and the dc internal resistance of the battery is:
R1＝ΔU1/ΔI
R2＝ΔU2/ΔI
wherein R is1Comprising an ohmic internal resistance and an interfacial charge transfer internal resistance, R2And characterizing the concentration polarization internal resistance of the battery under the condition.
3. And (3) carrying out alternating current internal resistance test on the battery after standing by using a battery internal resistance tester, and recording as R0Which characterizes the ohmic resistance of the cell, the electrochemical polarization resistance of the cell can be calculated from the following formulact＝R1-R0。
Example 2
A second embodiment of the present invention provides a battery internal resistance component measuring apparatus, as shown in fig. 5, including:
the battery pack comprises a series battery pack consisting of n lithium batteries in series, a charge-discharge controller (PCS) connected with the series battery pack and used for charging and discharging the series battery pack, an alternating current Internal Resistance Tester (IRT) used for outputting alternating current with small amplitude and calculating the internal resistance of the battery through detecting the voltage response of the battery, two analog switch groups (SA) used for controlling the connection of the alternating current internal resistance tester and a certain single battery, a data acquisition Device (DAQ) respectively connected with the charge-discharge controller and the analog switch groups and used for recording the terminal voltage and the circuit current of each single battery in the charge-discharge process, and an upper computer in communication connection with the data acquisition Device (DAQ), the charge-discharge controller (PCS) and the alternating current Internal Resistance Tester (IRT) and used for controlling the operation of each device and receiving data acquired by each device.
The working flow of the device for measuring the internal resistance component of the battery is further described with reference to the specific embodiment in the accompanying fig. 6:
1. the switch group A, B is switched off, the battery is charged to full charge state by a CCCV charging method, then the CCCV is discharged to cut-off voltage, wherein the cut-off current in the CV charging/discharging stage is not more than 1/20 rated capacity, or the battery is directly discharged to the cut-off voltage by 1/20C, the capacity value at the moment is recorded as new C, the battery is charged or discharged in short time, the SOC of the battery is in a range of 10% -90% after the discharge is finished, then the battery is kept still for not less than 10 minutes, and the discharge current is not less than 1C.
Under the condition of unknown battery capacity, the measurement can also be carried out by the following modes, for example, constant current charging is carried out for 12min by using a current I, after standing for 15min, constant current discharging is carried out for 6min, then standing is carried out for 15min, and the upper limit of the battery voltage is set as a control condition in the constant current charging process so as to avoid overcharging.
2. Recording the current change delta I and the instantaneous voltage jump delta U of the initial moment of the last standing of the battery1And a slow voltage change Δ U2Internal direct current resistance of battery
R1＝ΔU1/ΔI
R2＝ΔU2/ΔI
Wherein R is1Comprising an ohmic internal resistance and an interfacial charge transfer internal resistance, R2And characterizing the concentration polarization internal resistance of the battery under the condition.
3. And (2) disconnecting the charge and discharge controller, wherein the circuit current is 0, all batteries are kept still for more than 15min at the moment, activating a battery internal resistance tester IRT, closing switches A1 and B1, disconnecting A2A 3B 2B 3, connecting the IRT with the battery 1 at the moment, recording the internal resistance value of the battery every 10s after connecting for 30s in order to reduce the interference of inductance in the circuit, recording the resistance Ro (1) at the moment when the resistance value is not changed continuously for three times, similarly, when testing the battery 2, closing A2 and B2, disconnecting A1, A3, B1 and B3, and when testing the battery 3, closing A3 and B3, and disconnecting A1, A2, B1 and B2. The on-off of all the switches is automatically controlled by an upper computer.
4. Calculating the electrochemical polarization internal resistance of the battery: rct＝R1-R0(ii) a Concentration polarization internal resistance R of battery under 1C multiplying powerd＝R2。
Fig. 7 and 8 are schematic diagrams showing the comparison between the cell internal resistance component measuring method and device according to the present invention and the cell ohmic internal resistance/cell electrochemical polarization internal resistance measured by EIS method. It can be seen that the result measured by the method and the device for measuring the internal resistance component of the battery has better accuracy.
The above description of the embodiments is only intended to facilitate the understanding of the method of the invention and its core idea. It should be noted that, for those skilled in the art, it is possible to make various improvements and modifications to the present invention without departing from the principle of the present invention, and those improvements and modifications also fall within the scope of the claims of the present invention.
Claims (8)
1. A method for measuring the internal resistance component of a battery is characterized by comprising the following steps:
s1, updating the battery capacity data;
s2, charging or discharging the battery for a short time, standing for a plurality of times, and recording the transient voltage jump delta U at the initial standing time1And a slow voltage change Δ U2And further acquiring the direct current internal resistance of the battery:
R1＝ΔU1/ΔI
R2＝ΔU2/ΔI
wherein R is1Comprising an ohmic internal resistance and an interfacial charge transfer internal resistance, R2Representing the concentration polarization internal resistance of the battery under the condition, wherein delta I is charging or discharging current;
s3, carrying out alternating current internal resistance test on the battery after standing to obtain resistance R representing ohmic internal resistance of the battery0Further obtaining the electrochemical polarization internal resistance R of the batteryct＝R1-R0。
2. The method for measuring the internal resistance component of the battery according to claim 1, wherein the step S1 specifically includes:
firstly, the battery is charged to a full-charge state by adopting a CCCV charging method, and then the battery is discharged to a cut-off voltage by adopting the CCCV, wherein the cut-off current in the CV charging/discharging stage is not more than 1/20 rated capacity, or the battery is directly discharged to the cut-off voltage by adopting a current not more than 1/20C, and the capacity value at the moment is recorded as new C.
3. The method for measuring the internal resistance component of a battery as claimed in claim 1, wherein in step S2, when the battery is charged or discharged for a short time, the discharge current is not less than 1/5C, and the SOC of the battery after the discharge is within the range of 10% to 90%.
4. The method for measuring the internal resistance component of a battery according to claim 1, wherein the standing time is 10min or more in step S2.
5. A battery internal resistance component measuring device, characterized by comprising:
the charge and discharge controller is connected with the series battery pack and is used for carrying out direct current charge and discharge on the series battery pack;
the alternating current internal resistance tester is used for outputting small-amplitude alternating current to the monocells in the series battery pack and acquiring the internal resistance of the battery by detecting the voltage response of the battery;
the two analog switch groups are used for controlling the connection of the alternating current internal resistance tester and a certain single cell;
the data acquisition device or the battery management unit is respectively connected with the charge-discharge controller and the analog switch group and is used for controlling the action of the analog switch group and acquiring and recording the terminal voltage and the circuit current of each single battery in the charge-discharge process;
and the upper computer is in communication connection with the data acquisition device/battery management unit, the charge-discharge controller and the alternating current internal resistance tester and is used for controlling the operation of each device and receiving and processing data acquired by each device.
6. The apparatus for measuring a component of an internal resistance of a battery according to claim 5, wherein the data acquisition means has a test sampling frequency of 1HZ to 20 HZ.
7. The battery internal resistance component measuring device according to claim 5, wherein the battery management unit is further configured to charge each unit cell in the series battery pack in an equalizing manner to reduce a difference in SOC at the time of charge cut-off between the batteries.
8. The apparatus for measuring an internal resistance component of a battery according to claim 5, wherein the alternating current internal resistance tester outputs a small amplitude alternating current of 1 KHZ.
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Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN111999667A (en) * | 2020-08-21 | 2020-11-27 | 惠州亿纬锂能股份有限公司 | Method for evaluating internal resistance of battery |
| CN112557929A (en) * | 2020-11-13 | 2021-03-26 | 欣旺达电动汽车电池有限公司 | Battery internal resistance testing method, electronic device and storage medium |
| CN112986846A (en) * | 2021-03-09 | 2021-06-18 | 东软睿驰汽车技术（沈阳）有限公司 | Method and device for determining internal resistance of battery cell |
| CN113013470A (en) * | 2021-02-19 | 2021-06-22 | 芜湖天弋能源科技有限公司 | Lithium ion power battery cell grouping method |
| CN113093038A (en) * | 2021-03-03 | 2021-07-09 | 同济大学 | Power battery internal resistance composition analysis method based on pulse charge and discharge test |
| CN113884923A (en) * | 2021-11-03 | 2022-01-04 | 合肥国轩高科动力能源有限公司 | Lithium ion battery internal resistance screening method |
| CN114487886A (en) * | 2022-04-06 | 2022-05-13 | 宁德新能源科技有限公司 | Battery core flatulence detection method and device, battery management system and electronic equipment |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN111999667A (en) * | 2020-08-21 | 2020-11-27 | 惠州亿纬锂能股份有限公司 | Method for evaluating internal resistance of battery |
| CN112557929A (en) * | 2020-11-13 | 2021-03-26 | 欣旺达电动汽车电池有限公司 | Battery internal resistance testing method, electronic device and storage medium |
| CN113013470A (en) * | 2021-02-19 | 2021-06-22 | 芜湖天弋能源科技有限公司 | Lithium ion power battery cell grouping method |
| CN113093038A (en) * | 2021-03-03 | 2021-07-09 | 同济大学 | Power battery internal resistance composition analysis method based on pulse charge and discharge test |
| CN112986846A (en) * | 2021-03-09 | 2021-06-18 | 东软睿驰汽车技术（沈阳）有限公司 | Method and device for determining internal resistance of battery cell |
| CN112986846B (en) * | 2021-03-09 | 2024-06-04 | 东软睿驰汽车技术（沈阳）有限公司 | Method and device for determining internal resistance of battery cell |
| CN113884923A (en) * | 2021-11-03 | 2022-01-04 | 合肥国轩高科动力能源有限公司 | Lithium ion battery internal resistance screening method |
| CN113884923B (en) * | 2021-11-03 | 2023-07-11 | 合肥国轩高科动力能源有限公司 | Lithium ion battery internal resistance screening method |
| CN114487886A (en) * | 2022-04-06 | 2022-05-13 | 宁德新能源科技有限公司 | Battery core flatulence detection method and device, battery management system and electronic equipment |
| CN117590262A (en) * | 2023-11-29 | 2024-02-23 | 湖南银杏电池智能管理技术有限公司 | BMS product battery internal resistance self-adaptive measurement method |
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