CN115128488A - Method and device for determining SOC of lithium ion battery, medium and equipment - Google Patents

Method and device for determining SOC of lithium ion battery, medium and equipment Download PDF

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CN115128488A
CN115128488A CN202110328367.6A CN202110328367A CN115128488A CN 115128488 A CN115128488 A CN 115128488A CN 202110328367 A CN202110328367 A CN 202110328367A CN 115128488 A CN115128488 A CN 115128488A
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ion battery
lithium ion
soc
cpe
current
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肖晶
叶彩云
潘仪
舒时伟
冯天宇
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BYD 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]
    • G01R31/385—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
    • 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]
    • G01R31/378—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
    • 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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  • Charge And Discharge Circuits For Batteries Or The Like (AREA)

Abstract

The disclosure relates to a method and a device for determining SOC of a lithium ion battery, a medium and equipment. The method comprises the following steps: respectively obtaining a plurality of CPE numerical values of the lithium ion battery corresponding to a plurality of SOC (state of charge) of the lithium ion battery one by one at a plurality of temperatures of the lithium ion battery; fitting to obtain a plurality of first corresponding relations corresponding to the temperatures respectively according to the plurality of SOC values and the plurality of CPE values under the temperatures, wherein the first corresponding relations are linear relations between the SOC of the lithium ion battery and the CPE values of the lithium ion battery; acquiring the current temperature of the lithium ion battery; determining the current CPE value of the lithium ion battery; searching a first corresponding relation corresponding to the current temperature; and determining the SOC corresponding to the current CPE value of the lithium ion battery according to the searched first corresponding relation, and taking the SOC as the current SOC of the lithium ion battery. According to the scheme, the SOC of the lithium ion battery can be accurately determined, and the processing speed is high.

Description

Method and device for determining SOC of lithium ion battery, medium and equipment
Technical Field
The disclosure relates to the technical field of power battery detection, in particular to a method, a device, a medium and equipment for determining the SOC of a lithium ion battery.
Background
In new energy vehicles, the service life of the power battery directly affects the performance of the whole vehicle. Lithium ion power batteries (lithium ion batteries for short) are widely used in new energy vehicles, such as lithium iron phosphate batteries, due to their high safety, long cycle life and low cost.
The State Of Charge (SOC) is a key index Of a power battery, the SOC is determined at present by adopting an ampere-hour integration algorithm, and various correction strategies are added on the basis. The correction strategy can be generally divided into three types, the first type is a static correction method, namely, SOC correction is performed by using Open Circuit Voltage (OCV) of a battery static state; the second method is a full charge and discharge correction method, and SOC correction is carried out through full charge and discharge of a battery; in the third method, a charge-discharge multiplying power-dynamic voltage curve is calibrated in advance, and when the battery is used, the SOC is corrected by using the calibrated curve. Besides, a method for dynamically calculating the SOC by adopting a Kalman filtering mode is adopted, namely a first-order or second-order equation of the power battery is established, and the SOC is calculated in real time after the coefficients of the equation are calibrated through experiments.
The above SOC calculation methods each have certain drawbacks: because the OCV of the lithium iron phosphate battery is relatively flat, the SOC cannot be corrected by adopting static voltage in a plateau period; in the SOC non-plateau period, when the static voltage is used for judging, the battery needs to be placed for a long time; the SOC-OCV changes along with the attenuation of the battery, so the SOC calibrated by adopting the method is not accurate; when different charging and discharging multiplying power-dynamic voltage curves are calibrated for correction, even if a large number of parameters are calibrated, all user use conditions cannot be covered; when the SOC is calculated in a Kalman filtering mode, the hardware resource occupancy rate of a Battery Management System (BMS) is high, functions in a model can change along with the attenuation of a Battery, the calculation can be accurately performed after parameters of the life cycle of the whole Battery are calibrated, the required time is long, and the test quantity is large.
Disclosure of Invention
The invention aims to provide a method, a device, a medium and equipment capable of quickly and accurately determining the SOC of a lithium ion battery.
In order to achieve the above object, the present disclosure provides a method for determining an SOC of a lithium ion battery, the method including:
respectively acquiring a plurality of constant phase element CPE values of the lithium ion battery, which are in one-to-one correspondence with a plurality of charge states SOC of the lithium ion battery, at a plurality of temperatures of the lithium ion battery;
fitting according to the plurality of SOCs and the plurality of CPE numerical values at the plurality of temperatures to obtain a plurality of first corresponding relations corresponding to the plurality of temperatures respectively, wherein the first corresponding relations are linear relations between the SOC of the lithium ion battery and the CPE numerical values of the lithium ion battery;
acquiring the current temperature of the lithium ion battery;
determining a current CPE value of the lithium ion battery;
searching a first corresponding relation corresponding to the current temperature;
and determining the SOC corresponding to the current CPE value of the lithium ion battery according to the searched first corresponding relation, and taking the SOC as the current SOC of the lithium ion battery.
Optionally, the first correspondence satisfies the following formula:
Y 0 ＝a×S+b
wherein S is the SOC and Y of the lithium ion battery 0 And a and b are constants which are CPE values of the lithium ion battery.
Optionally, determining the current CPE value of the lithium ion battery comprises:
applying alternating current to the lithium ion battery, and acquiring a second corresponding relation between the impedance of the lithium ion battery and the frequency of the applied alternating current;
and obtaining a current CPE value of the lithium ion battery through a fitting method according to the second corresponding relation and a third corresponding relation, wherein the third corresponding relation is the corresponding relation among the CPE value of the lithium ion battery, the impedance of the lithium ion battery and the applied alternating current frequency, and the applied alternating current frequency is smaller than a preset frequency threshold.
Optionally, obtaining a plurality of CPE values of the lithium ion battery corresponding to a plurality of states of charge SOCs of the lithium ion battery in a one-to-one manner at a plurality of temperatures of the lithium ion battery respectively includes:
charging or discharging the lithium ion battery to enable the lithium ion battery to reach a preset first SOC;
if the lithium ion battery reaches the first SOC, placing the lithium ion battery at an ambient temperature with a preset first temperature for a preset time period so as to enable the temperature of the lithium ion battery to reach the first temperature;
applying alternating current to the lithium ion battery to obtain a second corresponding relation between the impedance of the lithium ion battery and the frequency of the applied alternating current;
obtaining a first CPE value corresponding to the first temperature and the first SOC through a fitting method according to the second corresponding relation and a third corresponding relation, wherein the third corresponding relation is the corresponding relation among the CPE value of the lithium ion battery, the impedance of the lithium ion battery and the frequency of the applied alternating current, and the frequency of the applied alternating current is smaller than a preset frequency threshold;
and charging or discharging the lithium ion battery to enable the lithium ion battery to reach a preset second SOC, controlling the temperature of the lithium ion battery to reach the first temperature, applying alternating current to the lithium ion battery, and continuing fitting until a plurality of CPE numerical values respectively corresponding to the first temperature and the preset SOCs are obtained.
Optionally, the third corresponding relation satisfies the following formula:
Figure BDA0002995441750000041
wherein, Z CPE Is the impedance of the lithium ion battery, Y 0 And the CPE value of the lithium ion battery, w is the frequency of the applied alternating current, n is a correction factor, and j is the unit of an imaginary number in a complex number.
Optionally, an apparatus for determining an SOC of a lithium ion battery, the apparatus includes:
the first acquisition module is used for acquiring a plurality of CPE values of the lithium ion battery, which are in one-to-one correspondence with a plurality of SOC (state of charge) of the lithium ion battery, at a plurality of temperatures of the lithium ion battery respectively;
a fitting module, configured to fit, according to the plurality of SOCs and the plurality of CPE values at the plurality of temperatures, a plurality of first corresponding relationships corresponding to the plurality of temperatures, respectively, where the first corresponding relationships are linear relationships between the SOC of the lithium ion battery and the CPE values of the lithium ion battery;
the second acquisition module is used for acquiring the current temperature of the lithium ion battery;
a first determining module, configured to determine a current CPE value of the lithium ion battery;
the searching module is used for searching a first corresponding relation corresponding to the current temperature;
and the second determining module is used for determining the SOC corresponding to the current CPE value of the lithium ion battery according to the searched first corresponding relation, and the SOC is used as the current SOC of the lithium ion battery.
Optionally, the first corresponding relation satisfies the following formula:
Y 0 ＝a×S+b
wherein S is the SOC and Y of the lithium ion battery 0 And a and b are constants which are CPE values of the lithium ion battery.
The present disclosure also provides a computer readable storage medium having stored thereon a computer program which, when executed by a processor, performs the steps of the above-described method provided by the present disclosure.
The present disclosure also provides an electronic device, comprising:
a memory having a computer program stored thereon;
a processor for executing the computer program in the memory to implement the steps of the above-described method provided by the present disclosure.
According to the technical scheme, under the conditions of multiple temperatures of the lithium ion battery, the multiple SOCs of the lithium ion battery and the multiple CPE values in one-to-one correspondence are obtained, then the first correspondence between the internal temperature of the lithium ion battery and the CPE values at each temperature is obtained through fitting, and therefore the current SOC of the lithium ion battery can be directly obtained through searching the current CPE value in the first correspondence corresponding to the current temperature by using the obtained current temperature of the lithium ion battery and the obtained current CPE value. Because the CPE value and the lithium ion concentration of the lithium ion battery have a stable corresponding relation at a fixed temperature, and the SOC represents the concentration of the lithium ion, the SOC of the battery is directly estimated through the characteristics (CPE value) of the lithium ion battery, so that the SOC of the lithium ion battery is accurately determined, and the scheme is simple and has high data processing speed.
Additional features and advantages of the disclosure will be set forth in the detailed description which follows.
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The accompanying drawings, which are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this specification, illustrate embodiments of the disclosure and together with the description serve to explain the disclosure without limiting the disclosure. In the drawings:
FIG. 1 is a flow chart of a method for determining a lithium ion battery SOC provided in accordance with an exemplary embodiment;
fig. 2 is a schematic graph illustrating a corresponding relationship between SOC and CPE when a temperature of the lithium ion battery is 25 ℃ according to an exemplary embodiment;
FIG. 3 is a block diagram of an apparatus for determining a lithium-ion battery SOC provided in accordance with an exemplary embodiment;
FIG. 4 is a block diagram of an electronic device shown in an exemplary embodiment.
Detailed Description
The following detailed description of the embodiments of the disclosure refers to the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating the present disclosure, are given by way of illustration and explanation only, not limitation.
For a lithium ion battery, the SOC represents the concentration of lithium ions in an electrode, and the value of a Constant Phase Angle Element (CPE) of the lithium ion battery is closely related to the concentration of the lithium ions, so that when the temperature is fixed, the SOC can be determined by directly using the CPE of the lithium ion battery, and the method is simple, has a small hardware resource occupancy rate for the BMS, and avoids errors caused by inaccurate voltage measurement compared with the SOC-OCV method.
Fig. 1 is a flowchart of a method for determining an SOC of a lithium ion battery according to an exemplary embodiment. As shown in fig. 1, the method may include the following steps.
Step S11, obtaining a plurality of CPE values of the lithium ion battery corresponding to the plurality of states of charge SOC of the lithium ion battery one-to-one at a plurality of temperatures of the lithium ion battery, respectively.
Step S12, fitting to obtain a plurality of first corresponding relations corresponding to the plurality of temperatures according to the plurality of SOCs and the plurality of CPE values at the plurality of temperatures, where the first corresponding relation is a linear relation between the SOC of the lithium ion battery and the CPE value of the lithium ion battery.
And step S13, acquiring the current temperature of the lithium ion battery.
Step S14, determining the current CPE value of the lithium ion battery.
In step S15, a first correspondence corresponding to the current temperature is found.
And step S16, determining the SOC corresponding to the current CPE value of the lithium ion battery according to the searched first corresponding relation, and taking the SOC as the current SOC of the lithium ion battery.
In step S11, a plurality of data pairs of SOC and CPE values may be obtained at a plurality of battery temperatures by way of an experiment. In the scheme, an equation of a linear relation (a first corresponding relation) between the battery SOC and the CPE value can be established respectively at each battery temperature, and parameters in the equation are determined by a fitting method.
The temperature of the lithium ion battery can be acquired in real time using a related technology (e.g., a temperature sensor). If the current temperature of the lithium ion battery and the current CPE value of the lithium ion battery are known, the current SOC of the corresponding lithium ion battery can be easily obtained by looking up the table in the first corresponding relationship corresponding to the current temperature.
According to the technical scheme, under the conditions of multiple temperatures of the lithium ion battery, the multiple SOCs of the lithium ion battery and the multiple CPE values in one-to-one correspondence are obtained, then the first correspondence between the internal temperature of the lithium ion battery and the CPE values at each temperature is obtained through fitting, and therefore the current SOC of the lithium ion battery can be directly obtained through searching the current CPE value in the first correspondence corresponding to the current temperature by using the obtained current temperature of the lithium ion battery and the obtained current CPE value. Because the CPE value and the lithium ion concentration of the lithium ion battery have a stable corresponding relation at a fixed temperature, and the SOC represents the lithium ion concentration, the SOC of the battery is directly estimated through the characteristics (CPE value) of the lithium ion battery, so that the SOC of the lithium ion battery is more accurately determined, and the scheme is simple and has high data processing speed.
In an embodiment, on the basis of fig. 1, the step of obtaining a plurality of CPE values of the lithium ion battery corresponding to a plurality of states of charge SOCs of the lithium ion battery in a one-to-one manner (step S11) at a plurality of temperatures of the lithium ion battery may include the following steps.
1. The lithium ion battery is charged or discharged such that the lithium ion battery reaches a predetermined first SOC (e.g., 0%).
2. If the lithium ion battery reaches the first SOC, the lithium ion battery is placed at an ambient temperature at a predetermined first temperature (e.g., 25 ℃) for a predetermined length of time (e.g., 2-6 hours) to bring the temperature of the lithium ion battery to the first temperature.
3. Applying an alternating current (e.g., a sinusoidal alternating current) to the lithium ion battery, and obtaining a second correspondence between the impedance of the lithium ion battery and the frequency of the applied alternating current. The alternating current may be applied to the lithium ion battery through the BMS of the vehicle.
As is well known to those skilled in the art, in the Electrochemical Impedance Spectroscopy (EIS) method, an alternating potential wave with a small amplitude and a different frequency is applied to an Electrochemical system, and the ratio of the alternating potential to the current signal (i.e., the Impedance of the system) is measured as a function of the frequency of the sine wave. An electrochemical workstation can be used for carrying out alternating current impedance test on the lithium ion battery, and an alternating current impedance spectrum, namely EIS, is collected. The conditions for testing the ac impedance of the battery may include, for example: the constant current mode, the frequency is 100 kHz-5 MHz, and the amplitude is 1.5-2.0A.
Because this scheme has greater accuracy at lower frequencies, the frequency of the applied alternating current is less than a predetermined frequency threshold (e.g., 0.1Hz, preferably 0.05 Hz).
4. And obtaining a first CPE numerical value corresponding to the first temperature and the first SOC through a fitting method according to the second corresponding relation and the third corresponding relation. The third corresponding relation is the corresponding relation between the CPE value of the lithium ion battery, the impedance of the lithium ion battery and the applied alternating current frequency. The second correspondence relationship may be a relationship in the related art.
Different impedances may be obtained at different frequencies, so that multiple sets of data can be fitted to obtain the CPE value closest to the actual value. For example, ZVIEW software may be used for the fitting.
Wherein, the third corresponding relation may satisfy the following formula:
Figure BDA0002995441750000081
wherein Z is CPE Is the impedance of a lithium ion battery, Y 0 CPE number for lithium ion batteryW is the frequency of the applied alternating current, n is the correction factor, and j is the unit of the imaginary number in the complex number.
5. And charging or discharging the lithium ion battery to enable the lithium ion battery to reach a preset second SOC, controlling the temperature of the lithium ion battery to reach a first temperature, applying alternating current to the lithium ion battery, and continuing fitting until a plurality of CPE numerical values respectively corresponding to the first temperature and the preset SOCs are obtained.
That is, the CPE values corresponding to the first temperature and the first SOC are obtained in steps 1-4, the lithium ion battery is controlled again to reach the first temperature and the second SOC, the corresponding CPE values are fitted, and so on until a plurality of CPE values corresponding to the first temperature and a predetermined plurality of SOCs (e.g., 0, 25%, 50%, 75%) are fitted, respectively. In this way, a first correspondence at a first temperature is obtained. Then, the same method is used to obtain the first corresponding relations with the preset temperatures.
In the embodiment, the CPE value of the lithium ion battery can be accurately determined by an EIS method and a fitting method, and the method is simple and easy to implement.
In yet another embodiment, the first correspondence may satisfy the following formula:
Y 0 ＝a×S+b (2)
wherein S is SOC and Y of the lithium ion battery 0 And a and b are constants which are CPE values of the lithium ion battery. The CPE value of the lithium ion battery and the SOC of the lithium ion battery are in the linear relation.
In this embodiment, the formula (2) is set in consideration of a substantially linear relationship between the SOC of the lithium ion battery and the CPE value of the lithium ion battery. The values of a and b at different battery temperatures can be obtained by fitting by substituting the SOC and CPE values at the battery temperatures into equation (2) through experiments in advance. Thus, if the values of a and b at the battery temperature are known, the current SOC of the lithium ion battery can be directly calculated by knowing the current temperature of the lithium ion battery and the current CPE value according to formula (2).
For example, the lithium ion battery can be charged and discharged in advance, the SOC of the lithium ion battery is adjusted to different values (0%, 25%, 50% and 75%) by discharging at 25 ℃, and after the temperature is kept constant for 2 to 6 hours, an alternating current impedance test is carried out on the lithium ion battery under different SOC states by using an electrochemical workstation, and an alternating current impedance spectrum is collected. Fitting to obtain a plurality of CPE values corresponding to the plurality of SOCs at 25 ℃, and substituting the plurality of SOCs and the corresponding plurality of CPE values into the formula (2) to obtain values of a and b by fitting.
In the embodiment, the linear relation between the SOC and the CPE of the lithium ion battery is obtained through pre-fitting, the result is accurate, the calculation method is simple, and the processing speed is high.
Fig. 2 is a schematic graph illustrating a corresponding relationship between SOC and CPE when a temperature of the lithium ion battery is 25 ℃ according to an exemplary embodiment. As shown in fig. 2, the horizontal axis represents SOC and the vertical axis represents CPE, and it can be seen from the graph that SOC and CPE satisfy the linear relationship shown in equation (2).
In a further embodiment, on the basis of fig. 1, the step of determining the current CPE value of the lithium ion battery (step S14) may comprise the steps of:
applying alternating current to the lithium ion battery to obtain a second corresponding relation between the impedance of the lithium ion battery and the frequency of the applied alternating current;
and obtaining the current CPE value of the lithium ion battery through a fitting method according to the second corresponding relation and the third corresponding relation. The third corresponding relation is the corresponding relation among a CPE value of the lithium ion battery, impedance of the lithium ion battery and the frequency of the applied alternating current, and the frequency of the applied alternating current is smaller than a preset frequency threshold value.
That is, the specific scheme for determining the current CPE value of the lithium ion battery in step S14 may be similar to that in step S11, and an ac impedance spectrum is collected by an EIS method and then fitted. The third corresponding relationship in this embodiment may also be the above formula (1), and will not be described in detail here.
Fig. 3 is a block diagram of a device for determining an SOC of a lithium ion battery according to an exemplary embodiment. As shown in fig. 3, the apparatus 300 for determining the SOC of the lithium ion battery may include a first obtaining module 301, a fitting module 302, a second obtaining module 303, a first determining module 304, a searching module 305, and a second determining module 306.
The first obtaining module 301 is configured to obtain a plurality of CPE values of the lithium ion battery, which correspond to a plurality of SOCs of the lithium ion battery one to one, at a plurality of temperatures of the lithium ion battery, respectively.
The fitting module 302 is configured to fit a plurality of first corresponding relationships corresponding to a plurality of temperatures according to a plurality of SOCs and a plurality of CPE values at the plurality of temperatures, where the first corresponding relationship is a linear relationship between the SOC of the lithium ion battery and the CPE value of the lithium ion battery.
The second obtaining module 303 is configured to obtain a current temperature of the lithium ion battery.
The first determination module 304 is used to determine the current CPE value of the lithium ion battery.
The lookup module 305 is configured to lookup a first correspondence corresponding to a current temperature.
The second determining module 306 is configured to determine, according to the searched first corresponding relationship, an SOC corresponding to the current CPE value of the lithium ion battery as the current SOC of the lithium ion battery.
Optionally, the first correspondence satisfies the following formula:
Y 0 ＝a×S+b
wherein S is SOC and Y of the lithium ion battery 0 And a and b are constants which are CPE values of the lithium ion battery.
Optionally, the first determining module 304 may include:
the acquisition submodule is used for applying alternating current to the lithium ion battery and acquiring a second corresponding relation between the impedance of the lithium ion battery and the frequency of the applied alternating current;
and the fitting submodule is used for obtaining the current CPE numerical value of the lithium ion battery through a fitting method according to the second corresponding relation and a third corresponding relation, wherein the third corresponding relation is the corresponding relation among the CPE numerical value of the lithium ion battery, the impedance of the lithium ion battery and the frequency of the applied alternating current, and the frequency of the applied alternating current is smaller than a preset frequency threshold.
Optionally, the third correspondence satisfies the following formula:
Figure BDA0002995441750000111
wherein Z is CPE Is the impedance of a lithium ion battery, Y 0 For the CPE value of a lithium ion battery, w is the applied alternating current frequency, n is the correction factor, and j is the unit of the imaginary number in the complex number.
Optionally, the first obtaining module 301 may include a charging and discharging sub-module, a temperature keeping sub-module, an alternating current applying sub-module, and a fitting sub-module.
The charging and discharging submodule is used for charging or discharging the lithium ion battery so as to enable the lithium ion battery to reach a preset first SOC.
The temperature keeping submodule is used for placing the lithium ion battery for a preset time at the ambient temperature with the preset first temperature if the lithium ion battery reaches the first SOC, so that the temperature of the lithium ion battery reaches the first temperature.
And the alternating current applying sub-module is used for applying alternating current to the lithium ion battery to obtain a second corresponding relation between the impedance of the lithium ion battery and the frequency of the applied alternating current.
The fitting submodule is used for obtaining a first CPE value corresponding to the first temperature and the first SOC through a fitting method according to a second corresponding relation and a third corresponding relation, wherein the third corresponding relation is the corresponding relation among the CPE value of the lithium ion battery, the impedance of the lithium ion battery and the applied alternating current frequency, and the applied alternating current frequency is smaller than a preset frequency threshold.
The charging and discharging submodule is further used for charging or discharging the lithium ion battery so that the lithium ion battery reaches a preset second SOC. The temperature keeping submodule is further used for controlling the temperature of the lithium ion battery to reach the first temperature again, the alternating current applying submodule is further used for applying alternating current to the lithium ion battery again, and the fitting submodule is further used for fitting again until a plurality of CPE numerical values respectively corresponding to the first temperature and the preset plurality of SOCs are obtained.
Optionally, the third correspondence satisfies the following formula:
Figure BDA0002995441750000121
wherein Z is CPE Impedance of lithium ion cell, Y 0 For the CPE value of a lithium ion battery, w is the applied alternating current frequency, n is the correction factor, and j is the unit of the imaginary number in the complex number.
With regard to the apparatus in the above-described embodiment, the specific manner in which each module performs the operation has been described in detail in the embodiment related to the method, and will not be elaborated here.
According to the technical scheme, under the conditions of multiple temperatures of the lithium ion battery, the multiple SOCs of the lithium ion battery and the multiple CPE values in one-to-one correspondence are obtained, then the first correspondence between the internal temperature of the lithium ion battery and the CPE values at each temperature is obtained through fitting, and therefore the current SOC of the lithium ion battery can be directly obtained through searching the current CPE value in the first correspondence corresponding to the current temperature by using the obtained current temperature of the lithium ion battery and the obtained current CPE value. Because the CPE value and the lithium ion concentration of the lithium ion battery have a stable corresponding relation at a fixed temperature, and the SOC represents the concentration of the lithium ion, the SOC of the battery is directly estimated through the characteristics (CPE value) of the lithium ion battery, so that the SOC of the lithium ion battery is accurately determined, and the scheme is simple and has high data processing speed.
The present disclosure also provides an electronic device comprising a memory and a processor.
The memory has a computer program stored thereon; the processor is used to execute the computer program in the memory to implement the steps of the above-described method provided by the present disclosure.
Fig. 4 is a block diagram of an electronic device 400 shown in an exemplary embodiment. As shown in fig. 4, the electronic device 400 may include: a processor 401 and a memory 402. The electronic device 400 may also include one or more of a multimedia component 403, an input/output (I/O) interface 404, and a communications component 405.
The processor 401 is configured to control the overall operation of the electronic device 400, so as to complete all or part of the steps in the above method for determining the SOC of the lithium ion battery. The memory 402 is used to store various types of data to support operation at the electronic device 400, such as instructions for any application or method operating on the electronic device 400 and application-related data, such as contact data, transmitted and received messages, pictures, audio, video, and so forth. The Memory 402 may be implemented by any type of volatile or non-volatile Memory device or combination thereof, such as Static Random Access Memory (SRAM), Electrically Erasable Programmable Read-Only Memory (EEPROM), Erasable Programmable Read-Only Memory (EPROM), Programmable Read-Only Memory (PROM), Read-Only Memory (ROM), magnetic Memory, flash Memory, magnetic disk or optical disk. The multimedia components 403 may include screen and audio components. Wherein the screen may be, for example, a touch screen and the audio component is used for outputting and/or inputting audio signals. For example, the audio component may include a microphone for receiving an external audio signal. The received audio signal may further be stored in the memory 402 or transmitted through the communication component 405. The audio assembly further comprises at least one speaker for outputting audio signals. The I/O interface 404 provides an interface between the processor 401 and other interface modules, such as a keyboard, mouse, buttons, etc. These buttons may be virtual buttons or physical buttons. The communication component 405 is used for wired or wireless communication between the electronic device 400 and other devices. Wireless Communication, such as Wi-Fi, bluetooth, Near Field Communication (NFC for short), 2G, 3G, 4G, NB-IOT, eMTC, or other 5G, etc., or a combination of one or more of them, which is not limited herein. The corresponding communication component 405 may therefore include: Wi-Fi modules, Bluetooth modules, NFC modules, and the like.
In an exemplary embodiment, the electronic Device 400 may be implemented by one or more Application Specific Integrated Circuits (ASICs), Digital Signal Processors (DSPs), Digital Signal Processing Devices (DSPDs), Programmable Logic Devices (PLDs), Field Programmable Gate Arrays (FPGAs), controllers, microcontrollers, microprocessors, or other electronic components for performing the above-described method for determining the SOC of the lithium ion battery.
In another exemplary embodiment, a computer readable storage medium comprising program instructions which, when executed by a processor, implement the steps of the above-described method for determining a lithium ion battery SOC is also provided. For example, the computer readable storage medium may be the memory 402 comprising program instructions executable by the processor 401 of the electronic device 400 to perform the above-described method for determining the SOC of the lithium ion battery.
The preferred embodiments of the present disclosure are described in detail with reference to the accompanying drawings, however, the present disclosure is not limited to the specific details of the above embodiments, and various simple modifications may be made to the technical solution of the present disclosure within the technical idea of the present disclosure, and these simple modifications all belong to the protection scope of the present disclosure.
It should be noted that the various features described in the above embodiments may be combined in any suitable manner without departing from the scope of the invention. In order to avoid unnecessary repetition, various possible combinations will not be separately described in this disclosure.
In addition, any combination of various embodiments of the present disclosure may be made, and the same should be considered as the disclosure of the present disclosure, as long as it does not depart from the spirit of the present disclosure.

Claims (9)

1. A method for determining SOC of a lithium ion battery, the method comprising:
respectively obtaining a plurality of constant phase element CPE values of the lithium ion battery corresponding to a plurality of charge states SOC of the lithium ion battery one to one at a plurality of temperatures of the lithium ion battery;
fitting according to the plurality of SOCs and the plurality of CPE numerical values at the plurality of temperatures to obtain a plurality of first corresponding relations corresponding to the plurality of temperatures respectively, wherein the first corresponding relations are linear relations between the SOC of the lithium ion battery and the CPE numerical values of the lithium ion battery;
acquiring the current temperature of the lithium ion battery;
determining a current CPE value of the lithium ion battery;
searching a first corresponding relation corresponding to the current temperature;
and determining the SOC corresponding to the current CPE value of the lithium ion battery according to the searched first corresponding relation, and taking the SOC as the current SOC of the lithium ion battery.
2. The method of claim 1, wherein the first correspondence satisfies the following equation:
Y 0 ＝a×S+b
wherein S is the SOC and Y of the lithium ion battery 0 And a and b are constants for CPE values of the lithium ion battery.
3. The method of claim 1, wherein determining the current CPE value for the li-ion battery comprises:
applying alternating current to the lithium ion battery to obtain a second corresponding relation between the impedance of the lithium ion battery and the frequency of the applied alternating current;
and obtaining a current CPE value of the lithium ion battery through a fitting method according to the second corresponding relation and a third corresponding relation, wherein the third corresponding relation is the corresponding relation among the CPE value of the lithium ion battery, the impedance of the lithium ion battery and the applied alternating current frequency, and the applied alternating current frequency is smaller than a preset frequency threshold.
4. The method of claim 1, wherein obtaining a plurality of CPE values for the lithium-ion battery corresponding one-to-one to a plurality of states of charge SOC of the lithium-ion battery at a plurality of temperatures of the lithium-ion battery, respectively, comprises:
charging or discharging the lithium ion battery to enable the lithium ion battery to reach a preset first SOC;
if the lithium ion battery reaches the first SOC, placing the lithium ion battery at an ambient temperature with a preset first temperature for a preset time period so as to enable the temperature of the lithium ion battery to reach the first temperature;
applying alternating current to the lithium ion battery to obtain a second corresponding relation between the impedance of the lithium ion battery and the frequency of the applied alternating current;
obtaining a first CPE value corresponding to the first temperature and the first SOC through a fitting method according to the second corresponding relation and a third corresponding relation, wherein the third corresponding relation is the corresponding relation among the CPE value of the lithium ion battery, the impedance of the lithium ion battery and the frequency of the applied alternating current, and the frequency of the applied alternating current is smaller than a preset frequency threshold;
and charging or discharging the lithium ion battery to enable the lithium ion battery to reach a preset second SOC, controlling the temperature of the lithium ion battery to reach the first temperature, applying alternating current to the lithium ion battery, and continuing fitting until a plurality of CPE numerical values respectively corresponding to the first temperature and the preset SOCs are obtained.
5. The method according to claim 3 or 4, wherein the third correspondence satisfies the following formula:
Figure FDA0002995441740000031
wherein Z is CPE Is the impedance of the lithium ion battery, Y 0 And w is the applied alternating current frequency, n is a correction factor, and j is the unit of an imaginary number in the complex number.
6. An apparatus for determining the SOC of a lithium ion battery, the apparatus comprising:
the first acquisition module is used for acquiring a plurality of CPE values of the lithium ion battery, which are in one-to-one correspondence with a plurality of charge states SOC of the lithium ion battery, at a plurality of temperatures of the lithium ion battery respectively;
a fitting module, configured to fit the plurality of SOCs and the plurality of CPE values at the plurality of temperatures to obtain a plurality of first corresponding relationships corresponding to the plurality of temperatures, respectively, where the first corresponding relationships are linear relationships between the SOC of the lithium ion battery and the CPE values of the lithium ion battery;
the second acquisition module is used for acquiring the current temperature of the lithium ion battery;
the first determining module is used for determining the current CPE value of the lithium ion battery;
the searching module is used for searching a first corresponding relation corresponding to the current temperature;
and the second determining module is used for determining the SOC corresponding to the current CPE value of the lithium ion battery according to the searched first corresponding relation, and the SOC is used as the current SOC of the lithium ion battery.
7. The apparatus of claim 6, wherein the first correspondence satisfies the following equation:
Y 0 ＝a×S+b
wherein S is the SOC and Y of the lithium ion battery 0 And a and b are constants which are CPE values of the lithium ion battery.
8. A computer-readable storage medium, on which a computer program is stored which, when being executed by a processor, carries out the steps of the method according to any one of claims 1 to 5.
9. An electronic device, comprising:
a memory having a computer program stored thereon;
a processor for executing the computer program in the memory to carry out the steps of the method of any one of claims 1 to 5.
CN202110328367.6A 2021-03-26 2021-03-26 Method and device for determining SOC of lithium ion battery, medium and equipment Pending CN115128488A (en)

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