CN115128463A - Method and device, medium and equipment for estimating internal temperature of lithium ion battery - Google Patents

Method and device, medium and equipment for estimating internal temperature of lithium ion battery Download PDF

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CN115128463A
CN115128463A CN202110328363.8A CN202110328363A CN115128463A CN 115128463 A CN115128463 A CN 115128463A CN 202110328363 A CN202110328363 A CN 202110328363A CN 115128463 A CN115128463 A CN 115128463A
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ion battery
lithium ion
cpe
internal temperature
value
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冯天宇
舒时伟
邓林旺
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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]
    • G01R31/367—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 present disclosure relates to a method, apparatus, medium, and device for estimating a temperature in a lithium ion battery. The method comprises the following steps: respectively acquiring a plurality of CPE numerical values which are in one-to-one correspondence with a plurality of internal temperatures of the lithium ion battery under a plurality of charge states of the lithium ion battery; fitting to obtain a first corresponding relation when the temperature in the lithium ion battery is lower than zero degrees centigrade according to a plurality of internal temperatures and a plurality of CPE values under a plurality of charge states, wherein the first corresponding relation is a linear relation between the internal temperature of the lithium ion battery and the CPE value of the lithium ion battery; determining a current CPE value of the lithium ion battery; finding out an internal temperature corresponding to the current CPE numerical value in the first corresponding relation; and if the searched internal temperature is less than zero centigrade, determining the searched internal temperature as the current internal temperature of the lithium ion battery. The scheme can accurately determine the internal temperature of the lithium ion battery when the internal temperature is lower than zero centigrade, and is simple and high in data processing speed.

Description

Method and device, medium and equipment for estimating internal temperature of lithium ion battery
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 estimating the internal temperature of a lithium ion battery.
Background
The internal temperature of the power battery during charging and discharging directly affects the operational performance of the electric vehicle, such as cycle life, efficiency, reliability, and safety, and therefore, it is necessary to detect the internal temperature of the power battery timely and accurately.
At present, temperature sensors cannot be arranged inside the cells due to technical limitations. Under certain operating conditions, the temperature difference between the temperature at the location of the sensor arrangement and the actual temperature inside the cell can reach up to 10 ℃ or more. Meanwhile, the temperature difference is changed in real time along with the change of the working state of the battery and is not a fixed value. If the temperature in the battery is inaccurate, errors can be brought to calculation results such as electric quantity state estimation of the battery core, thermal runaway early warning and the like. More importantly, the internal temperature of the cell reaches the critical point of thermal runaway earlier than the surface temperature, which may lead to thermal runaway and even to severe explosion.
The surface temperature cannot show the thermal behavior of the entire battery and the center temperature is not easily measured. Therefore, estimating the internal temperature of the cells of a power battery, as well as monitoring the safe operation of the battery and preventing thermal runaway are very important and urgent tasks. The existing algorithm for estimating the temperature in the battery generally estimates the internal temperature of the battery by establishing a temperature model and fitting model parameters with the algorithm (offline calibration or online estimation).
Disclosure of Invention
The purpose of the present disclosure is to provide a method, an apparatus, a medium, and a device for estimating the internal temperature of a lithium ion battery, which can estimate the internal temperature of the lithium ion battery quickly and accurately.
In order to achieve the above object, the present disclosure provides a method of estimating a temperature in a lithium ion battery, the method including:
respectively acquiring a plurality of constant phase element CPE values of the lithium ion battery, which correspond to a plurality of internal temperatures of the lithium ion battery one by one, in a plurality of charge states of the lithium ion battery;
fitting to obtain a first corresponding relation when the internal temperature of the lithium ion battery is less than zero degrees centigrade according to the internal temperatures and the CPE numerical values in the charge states, wherein the first corresponding relation is a linear relation between the internal temperature of the lithium ion battery and the CPE numerical value of the lithium ion battery;
determining a current constant phase angle element (CPE) value of the lithium ion battery;
finding out an internal temperature corresponding to the current CPE numerical value in the first corresponding relation;
and if the searched internal temperature is less than zero centigrade, determining the searched internal temperature as the current internal temperature of the lithium ion battery.
Optionally, determining the current CPE value of the lithium ion battery comprises:
acquiring a second corresponding relation between the impedance of the lithium ion battery and the frequency of the applied alternating current by an Electrochemical Impedance Spectroscopy (EIS) method, wherein the frequency of the applied alternating current is less than a predetermined frequency threshold;
and determining the current CPE numerical value of the lithium ion battery according to the second corresponding relation.
Optionally, determining the current CPE value of the lithium ion battery according to the second correspondence includes:
determining a third corresponding relation among the impedance of the lithium ion battery, the applied alternating current frequency and the CPE value of the lithium ion battery;
and calculating the current CPE value of the lithium ion battery through a fitting algorithm according to the second corresponding relation and the third corresponding relation.
Optionally, the third correspondence satisfies the following formula:
Figure BDA0002995441640000021
wherein Z (ω) is a function of the impedance Z of the lithium ion battery as a function of the frequency ω of the applied alternating current, A 1 Is the CPE value of the lithium ion battery, gamma is a correction factor, j is the unit of an imaginary number in a complex number, R 1 And R 2 And the resistance value of a resistor connected with the CEP in series in the equivalent circuit model of the lithium ion battery is shown.
Optionally, calculating a current CPE value of the lithium ion battery by a fitting algorithm according to the second corresponding relationship and the third corresponding relationship, including:
performing iterative fitting according to the following formula to obtain a CPE numerical value matched with the ideal value of gamma, wherein the CPE numerical value is used as the current CPE numerical value of the lithium ion battery:
Z(ω,p)＝Z 1 (ω,p)+j·Z 2 (ω,p)
wherein Z (ω, p) is a function of the impedance Z of the lithium ion battery as a function of the frequency ω of the applied alternating current and a parameter set p, wherein the parameters in the parameter set p include γ, A 1 、R 1 And R 2 ，Z 1 (ω, p) is the real part of Z (ω, p), Z 2 (ω, p) is the imaginary part of Z (ω, p).
Optionally, in the iterative fitting, a CPE value in a parameter group p corresponding to the impedance of the lithium ion battery that satisfies the following formula is taken as a current CPE value of the lithium ion battery:
Figure BDA0002995441640000031
RMSE(p)＜a
wherein Z _ real is the real part of the impedance of the lithium ion battery, Z _ imag is the imaginary part of the impedance of the lithium ion battery, a is a constant, and n is the number of applied alternating current frequencies.
Optionally, the first corresponding relation satisfies the following formula:
A 1 ＝k×T+b
wherein A is 1 And k and b are constants, and T is the internal temperature of the lithium ion battery.
The present disclosure also provides a device for estimating an internal temperature of a lithium ion battery, the device including:
the acquisition module is used for acquiring a plurality of constant phase element CPE values of the lithium ion battery, which correspond to a plurality of internal temperatures of the lithium ion battery one by one, respectively in a plurality of charge states of the lithium ion battery;
a fitting module, configured to fit the internal temperatures and the CPE values in the multiple states of charge to obtain a first corresponding relationship when the internal temperature of the lithium ion battery is less than zero degrees centigrade, where the first corresponding relationship is a linear relationship between the internal temperature of the lithium ion battery and the CPE value of the lithium ion battery;
a first determining module, configured to determine a current constant phase angle element CPE value of the lithium ion battery;
the searching module is used for searching the internal temperature corresponding to the current CPE numerical value in the first corresponding relation;
and the second determining module is used for determining the searched internal temperature as the current internal temperature of the lithium ion battery if the searched internal temperature is less than zero degrees centigrade.
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 method provided by the present disclosure.
According to the technical scheme, under a plurality of charge states of the lithium ion battery, a plurality of internal temperatures of the lithium ion battery and a plurality of CPE values in one-to-one correspondence are obtained, then the first correspondence between the internal temperatures and the CPE values is obtained through fitting when the internal temperature of the lithium ion battery is lower than zero degrees centigrade, and therefore the determined current CPE value of the lithium ion battery can be used for directly searching in the first correspondence. When the temperature is lower than zero degree centigrade, the CPE value of the lithium ion battery and the temperature in the lithium ion battery have a stable linear relation and are basically irrelevant to the SOC, so that when the temperature is lower than zero degree centigrade, the SOC can be ignored, and the temperature in the lithium ion battery can be estimated directly through the CPE value reflecting the self characteristics of the lithium ion battery, so that the temperature in the lithium ion battery can be determined more accurately, and the scheme is simple and has high data processing speed.
Additional features and advantages of the present 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 of estimating a temperature within a lithium ion battery provided by an exemplary embodiment;
FIG. 2 is a graph of estimated internal temperature of a lithium-ion battery as a function of SOC, CPE values provided by an exemplary embodiment;
FIG. 3 is an equivalent circuit diagram of an estimated lithium ion battery provided by an exemplary embodiment;
FIG. 4 is a block diagram of an apparatus for estimating lithium-ion battery internal temperature provided by an exemplary embodiment;
FIG. 5 is a block diagram of an electronic device, shown in an exemplary embodiment.
Detailed Description
The following detailed description of specific embodiments of the present disclosure is provided in connection with 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.
When the internal temperature Of the lithium ion battery is below zero degrees centigrade, the value Of the Constant Phase Angle Element (CPE) in the lower frequency range is not substantially correlated with the State Of Charge (SOC) Of the battery, and the value Of the CPE has a relatively stable linear relationship with the internal temperature Of the lithium ion. Therefore, in the scheme of the disclosure, when the internal temperature of the lithium ion battery is below zero degrees centigrade, the internal temperature of the lithium ion battery is directly estimated by the CPE value reflecting the characteristics of the lithium ion battery by ignoring the SOC, so that the internal temperature of the lithium ion battery can be determined more accurately.
FIG. 1 is a flow chart of a method of estimating lithium ion battery internal temperature provided by an exemplary embodiment. As shown in fig. 1, the method may include the following steps.
Step S11, acquiring a plurality of CPE values of the lithium ion battery corresponding to a plurality of internal temperatures of the lithium ion battery one to one, respectively under a plurality of SOCs of the lithium ion battery.
And step S12, fitting according to a plurality of internal temperatures and a plurality of CPE values under a plurality of SOC to obtain a first corresponding relation when the internal temperature of the lithium ion battery is less than zero centigrade, wherein the first corresponding relation is a linear relation between the internal temperature of the lithium ion battery and the CPE value of the lithium ion battery.
Step S13, determining the current CPE value of the lithium ion battery.
Step S14, finding the internal temperature corresponding to the current CPE value in the first correspondence.
And step S15, if the searched internal temperature is less than zero centigrade, determining the searched internal temperature as the current internal temperature of the lithium ion battery.
In step S11, a plurality of data pairs of the internal temperature and the CPE value obtained at a plurality of SOCs may be plotted experimentally. FIG. 2 is a graph of estimating internal temperature of a lithium-ion battery as a function of SOC and CPE values provided by an exemplary embodiment. As shown in fig. 2, the three curves represent the relationship between the CPE value and the in-cell temperature T at SOC of 0.25, 0.5 and 0.75, respectively. It can be seen that the internal temperature T of the battery is substantially independent of SOC and has a stable linear relationship with CPE value at internal temperatures below zero degrees celsius. In the scheme, an equation of a linear relation (first corresponding relation) between the temperature T in the battery and the CPE numerical value can be established, and parameters in the equation are determined by a fitting method.
The current CPE value of the lithium ion battery can be obtained according to the method in the related art. The first corresponding relationship may be stored after being calibrated in advance by a test method. If the current CPE value of the lithium ion battery is obtained, the current internal temperature of the corresponding lithium ion battery is easily obtained in the first corresponding relationship by looking up a table, and when the found internal temperature is less than zero degrees centigrade, the current internal temperature can be determined, otherwise, when the internal temperature of the lithium ion battery is greater than zero degrees centigrade, the SOC affects the linear relationship between the internal temperature and the CPE value, so that the found internal temperature can be considered to be inaccurate, and at this time, the internal temperature of the lithium ion battery can be determined by other methods.
According to the technical scheme, under a plurality of charge states of the lithium ion battery, a plurality of internal temperatures of the lithium ion battery and a plurality of CPE values in one-to-one correspondence are obtained, then the first correspondence between the internal temperatures and the CPE values is obtained through fitting when the internal temperature of the lithium ion battery is lower than zero degrees centigrade, and therefore the determined current CPE value of the lithium ion battery can be used for directly searching in the first correspondence. When the temperature is lower than zero degree centigrade, the CPE value of the lithium ion battery and the temperature in the lithium ion battery have a stable linear relation and are basically irrelevant to the SOC, so that when the temperature is lower than zero degree centigrade, the SOC can be ignored, and the temperature in the lithium ion battery can be estimated directly through the CPE value reflecting the self characteristics of the lithium ion battery, so that the temperature in the lithium ion battery can be determined more accurately, and the scheme is simple and has high data processing speed.
In yet another embodiment, on the basis of fig. 1, determining the current CPE value of the lithium ion battery (step S13) may include: a second correspondence between the Impedance of the lithium ion battery and the frequency of the applied alternating current is obtained by an Electrochemical Impedance Spectroscopy (EIS) method. Wherein the frequency of the applied alternating current is less than a predetermined frequency threshold; and determining the current CPE value of the lithium ion battery according to the second corresponding relation.
In the EIS method, an alternating potential wave of small amplitude at different frequencies 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. The second correspondence relationship is a relationship between the impedance of the lithium ion battery and the frequency of the applied alternating current obtained by the EIS method when the frequency of the applied alternating current is less than a predetermined frequency threshold.
For example, in a charging process in which an electric vehicle is connected to a charging post, a charging current signal less than a predetermined frequency threshold (e.g., less than 0.1Hz, preferably 0.01Hz to 0.1Hz) is sent to the electric vehicle by the charging post, and at this time, a Battery Management System (BMS) synchronously samples a current signal and a voltage signal of the Battery and records the current signal and the voltage signal. Carrying out Fourier transform on the sampled current and voltage to obtain amplitude and phase information of the internal resistance of the battery with corresponding frequency, namely a second corresponding relation; in the discharging process, namely in the normal running process of the electric vehicle, the current signal and the voltage signal of the battery are synchronously sampled, and the current signal and the voltage signal are recorded. The sampled currents and voltages are then fourier expanded, where the aliased signal frequency can be decomposed into a sinusoidal superposition of frequencies. And then carrying out fast Fourier transform, and screening out effective signals of effective frequency from the signals to obtain amplitude and phase information of the resistor with the frequency of (0.01 Hz-0.1 Hz), namely a second corresponding relation.
In the embodiment, the current CPE value is determined by the impedance characteristic of the lithium ion battery determined by the EIS method, and the accuracy is high.
In another embodiment, the determining the current CPE value of the lithium ion battery according to the second correspondence may include: determining a third corresponding relation among the impedance of the lithium ion battery, the applied alternating current frequency and the CPE value of the lithium ion battery; and calculating the current CPE value of the lithium ion battery through a fitting algorithm according to the second corresponding relation and the third corresponding relation.
The third correspondence relationship may be determined according to a relationship among impedance of the lithium ion battery, an applied alternating current frequency, and a CPE value of the lithium ion battery in the related art. For example, ZVIEW software may be used for the fitting.
In the embodiment, the current CPE value of the lithium ion battery is accurately determined by a fitting method, and the method is simple and easy to implement.
The equivalent circuit of the lithium ion battery can be simplified to be similar to a first-order RC circuit. Fig. 3 is an equivalent circuit diagram of an estimated lithium ion battery provided by an exemplary embodiment. As shown in fig. 3, the equivalent circuit includes a resistor R1, a resistor R2, a first CPE a1 and a second CPE a 2. The resistor R2 and the second CPE A2 are connected in parallel and then connected in series with the resistor R1 and the first CPE A1. Since the present solution is implemented at a lower frequency (less than the predetermined frequency threshold), the second CPE a2 can be ignored, and the first CEP a1 is the CPE of the li-ion battery.
On the basis of the equivalent circuit of fig. 3, at low frequencies, the third correspondence relationship may satisfy the following formula:
Figure BDA0002995441640000091
wherein Z (ω) is a function of the impedance Z of the lithium ion battery as a function of the frequency ω of the applied alternating current, A 1 Is the CPE number (number of the first CEP 1) of the lithium ion battery, gamma is the correction factor (fractional order of the CEP), j is the unit of imaginary number in the complex number, R 1 And R 2 The resistance values of the resistors R1 and R2 connected in series with the CPE (first CEP a1) of the lithium ion battery in the equivalent circuit model of the lithium ion battery, respectively.
The impedance of the equivalent circuit can be written separately as both real and imaginary terms, depending on different frequencies ω and different sets of parameters p. In another embodiment, the calculating, according to the second corresponding relationship and the third corresponding relationship, a current CPE value of the lithium ion battery at the applied ac frequency by a fitting algorithm may include:
performing iterative fitting according to the following formula to obtain a CPE numerical value matched with the ideal value of gamma, wherein the CPE numerical value is used as the current CPE numerical value of the lithium ion battery:
Z(ω,p)＝Z 1 (ω,p)+j·Z 2 (ω,p) (2)
wherein Z (ω, p) is a function of the impedance Z of the lithium ion battery as a function of the frequency ω of the applied alternating current and a parameter set p, wherein the parameters in the parameter set p include γ, A 1 、R 1 And R 2 ，Z 1 (ω, p) is the real part of Z (ω, p), Z 2 (ω, p) is the imaginary part of Z (ω, p).
In the formula (2), gamma and A are 1 、R 1 And R 2 As a set of parameters, in the test, can be based onThe obtained amplitude and phase information of the impedance of the lithium ion battery is converted into numerical values of a real part and an imaginary part of the impedance, and on the basis, fitting is carried out according to a related algorithm to obtain an optimal parameter solution in the formula.
In the embodiment, the impedance is written into a real part form and an imaginary part form, and the fitting is performed by using the numerical values of the real part and the imaginary part, so that the accuracy is high.
For example, in the iterative fitting, the CPE value in the parameter group p corresponding to the impedance of the lithium ion battery satisfying the following formula (3) may be used as the current CPE value of the lithium ion battery:
Figure BDA0002995441640000101
wherein Z _ real is the real part of the impedance of the lithium ion battery, Z _ imag is the imaginary part of the impedance of the lithium ion battery, a is a constant, n is the number of applied alternating current frequencies, ω i Is the ith alternating current frequency in 1-n.
In formula (3), an optimal parameter solution is obtained by using an iterative fitting algorithm so that the root mean square error rmse (p) is smaller than the constant a. In the embodiment, fitting is performed according to the root mean square error, the steps are simple, and the accuracy of the result is high.
In one embodiment, the first correspondence may satisfy the following formula:
A 1 ＝k×T+b (4)
wherein, A 1 And (4) the CPE value of the lithium ion battery, k and b are constants, and T is the internal temperature of the lithium ion battery.
The parameters k and b can be determined experimentally beforehand so that the temperature T in the battery has a defined relationship with the CPE value. Therefore, the internal temperature of the lithium ion battery can be directly calculated by knowing the current CPE value of the lithium ion battery.
In the embodiment, the linear relation between the CPE value and the internal temperature 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. 4 is a block diagram of an apparatus for estimating the internal temperature of a lithium ion battery according to an exemplary embodiment. As shown in fig. 4, the apparatus 400 for estimating the internal temperature of the lithium ion battery may include an obtaining module 401, a fitting module 402, a first determining module 403, a searching module 404, and a second determining module 405.
The obtaining module 401 is configured to obtain a plurality of CPE values of the lithium ion battery, where the CPE values correspond to a plurality of internal temperatures of the lithium ion battery one to one, in a plurality of SOCs of the lithium ion battery, respectively;
the fitting module 402 is configured to fit a first corresponding relationship when the internal temperature of the lithium ion battery is less than zero degrees centigrade according to a plurality of internal temperatures and a plurality of CPE values under a plurality of SOCs, where the first corresponding relationship is a linear relationship between the internal temperature of the lithium ion battery and the CPE value of the lithium ion battery;
the first determination module 403 is used to determine the current CPE value of the lithium ion battery.
The lookup module 404 is configured to find an internal temperature corresponding to the current CPE value in the first correspondence.
The second determining module 405 is configured to determine the searched internal temperature as the current internal temperature of the lithium ion battery if the searched internal temperature is less than zero degrees centigrade.
Optionally, the first determining module 403 may include an obtaining sub-module and a first determining sub-module.
The acquisition submodule is used for acquiring a second corresponding relation between the impedance of the lithium ion battery and the applied alternating current frequency through an EIS method, wherein the applied alternating current frequency is smaller than a preset frequency threshold;
and the first determining submodule is used for determining the current CPE value of the lithium ion battery according to the second corresponding relation.
Optionally, the first determination submodule may include a second determination submodule and a calculation submodule.
And the second determining submodule is used for determining a third corresponding relation among the impedance of the lithium ion battery, the applied alternating current frequency and the CPE value of the lithium ion battery.
And the calculating submodule is used for calculating the current CPE value of the lithium ion battery through a fitting algorithm according to the second corresponding relation and the third corresponding relation.
Optionally, the third correspondence satisfies the following formula:
Figure BDA0002995441640000111
wherein Z (ω) is a function of the impedance Z of the lithium ion battery as a function of the frequency ω of the applied alternating current, A 1 Is the CPE value of the lithium ion battery, gamma is a correction factor, j is the unit of an imaginary number in a complex number, R 1 And R 2 The resistance value of the resistor connected with the CEP in series in the equivalent circuit model of the lithium ion battery is shown.
Optionally, the computation submodule may comprise an iteration submodule.
The iteration submodule is used for carrying out iteration fitting according to the following formula to obtain a CPE numerical value matched with the ideal value of gamma under the applied alternating current frequency, and the CPE numerical value is used as the current CPE numerical value of the lithium ion battery:
Z(ω,p)＝Z 1 (ω,p)+j·Z 2 (ω,p)
wherein Z (ω, p) is a function of impedance Z of the lithium ion battery as a function of frequency ω of the applied alternating current and a parameter set p, wherein parameters in the parameter set p include γ and A 1 、R 1 And R 2 ，Z 1 (ω, p) is the real part of Z (ω, p), Z 2 (ω, p) is the imaginary part of Z (ω, p).
Optionally, in the iterative fitting of the iterative submodule, the CPE value in the parameter group p corresponding to the test value of the impedance of the lithium ion battery that satisfies the following formula is taken as the current CPE value of the lithium ion battery:
Figure BDA0002995441640000121
RMSE(p)＜a
wherein Z _ real is the real part of the impedance of the lithium ion battery, Z _ imag is the imaginary part of the impedance of the lithium ion battery, a is a constant, and n is the number of applied alternating current frequencies.
Optionally, the first correspondence satisfies the following formula:
A 1 ＝k×T+b
wherein A is 1 And k and b are constants, and T is the internal temperature of the lithium ion battery.
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 a plurality of charge states of the lithium ion battery, a plurality of internal temperatures of the lithium ion battery and a plurality of CPE values in one-to-one correspondence are obtained, then the first correspondence between the internal temperatures and the CPE values is obtained through fitting when the internal temperature of the lithium ion battery is lower than zero degrees centigrade, and therefore the determined current CPE value of the lithium ion battery can be used for directly searching in the first correspondence. When the temperature is lower than zero degree centigrade, the CPE value of the lithium ion battery and the temperature in the lithium ion battery have a stable linear relation and are basically irrelevant to the SOC, so that when the temperature is lower than zero degree centigrade, the SOC can be ignored, and the temperature in the lithium ion battery can be estimated directly through the CPE value reflecting the self characteristics of the lithium ion battery, so that the temperature in the lithium ion battery can be determined more accurately, 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 realize the steps of the above method provided by the present disclosure.
Fig. 5 is a block diagram of an electronic device 500 shown in accordance with an example embodiment. As shown in fig. 5, the electronic device 500 may include: a processor 501 and a memory 502. The electronic device 500 may also include one or more of a multimedia component 503, an input/output (I/O) interface 504, and a communication component 505.
The processor 501 is configured to control the overall operation of the electronic device 500, so as to complete all or part of the steps in the above method for estimating the internal temperature of the lithium ion battery. The memory 502 is used to store various types of data to support operation at the electronic device 500, such as instructions for any application or method operating on the electronic device 500 and application-related data, such as contact data, messaging, pictures, audio, video, and so forth. The Memory 502 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 component 503 may include a screen and an audio component. 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 external audio signals. The received audio signal may further be stored in the memory 502 or transmitted through the communication component 505. The audio assembly also includes at least one speaker for outputting audio signals. The I/O interface 504 provides an interface between the processor 501 and other interface modules, such as a keyboard, mouse, buttons, and the like. These buttons may be virtual buttons or physical buttons. The communication component 505 is used for wired or wireless communication between the electronic device 500 and other devices. Wireless Communication, such as Wi-Fi, bluetooth, Near Field Communication (NFC), 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 505 may thus comprise: Wi-Fi module, Bluetooth module, NFC module, etc.
In an exemplary embodiment, the electronic Device 500 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 estimating the internal temperature of a 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 of estimating the temperature in a lithium ion battery is also provided. For example, the computer readable storage medium may be the memory 502 described above that includes program instructions that are executable by the processor 501 of the electronic device 500 to perform the method described above for estimating the battery temperature of a 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. To avoid unnecessary repetition, the disclosure does not separately describe various possible combinations.
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 (10)

1. A method of estimating the temperature within a lithium ion battery, the method comprising:
respectively acquiring a plurality of constant phase element CPE values of the lithium ion battery, which correspond to a plurality of internal temperatures of the lithium ion battery one by one, in a plurality of charge states of the lithium ion battery;
fitting to obtain a first corresponding relation when the internal temperature of the lithium ion battery is less than zero degrees centigrade according to the internal temperatures and the CPE values in the charge states, wherein the first corresponding relation is a linear relation between the internal temperature of the lithium ion battery and the CPE value of the lithium ion battery;
determining a current constant phase angle element (CPE) value of the lithium ion battery;
finding out an internal temperature corresponding to the current CPE numerical value in the first corresponding relation;
and if the searched internal temperature is less than zero centigrade, determining the searched internal temperature as the current internal temperature of the lithium ion battery.
2. The method of claim 1, wherein determining the current CPE value for the li-ion battery comprises:
acquiring a second corresponding relation between the impedance of the lithium ion battery and the frequency of the applied alternating current by an Electrochemical Impedance Spectroscopy (EIS) method, wherein the frequency of the applied alternating current is less than a predetermined frequency threshold;
and determining the current CPE value of the lithium ion battery according to the second corresponding relation.
3. The method of claim 2, wherein determining the current CPE value for the li-ion battery based on the second mapping comprises:
determining a third corresponding relation among the impedance of the lithium ion battery, the applied alternating current frequency and the CPE value of the lithium ion battery;
and calculating the current CPE value of the lithium ion battery through a fitting algorithm according to the second corresponding relation and the third corresponding relation.
4. The method according to claim 3, wherein the third correspondence satisfies the following formula:
Figure FDA0002995441630000021
wherein Z (ω) is a function of the impedance Z of the lithium ion battery as a function of the frequency ω of the applied alternating current, A 1 Is the CPE value of the lithium ion battery, gamma is a correction factor, j is the unit of an imaginary number in a complex number, R 1 And R 2 And the resistance value of a resistor connected with the CEP in series in the equivalent circuit model of the lithium ion battery is shown.
5. The method according to claim 4, wherein the calculating a current CPE value of the lithium ion battery according to the second correspondence and the third correspondence by a fitting algorithm comprises:
performing iterative fitting according to the following formula to obtain a CPE numerical value matched with the ideal value of gamma, wherein the CPE numerical value is used as the current CPE numerical value of the lithium ion battery:
Z(ω,p)＝Z 1 (ω,p)+j·Z 2 (ω,p)
wherein Z (ω, p) is a function of the impedance Z of the lithium ion battery as a function of the frequency ω of the applied alternating current and a parameter set p, wherein the parameters in the parameter set p include γ, A 1 、R 1 And R 2 ，Z 1 (ω, p) is the real part of Z (ω, p), Z 2 (ω, p) is the imaginary part of Z (ω, p).
6. The method according to claim 5, wherein in the iterative fitting, the CPE value in the parameter group p corresponding to the impedance of the lithium ion battery satisfying the following formula is taken as the current CPE value of the lithium ion battery:
Figure FDA0002995441630000022
RMSE(p)＜a
wherein Z _ real is the real part of the impedance of the lithium ion battery, Z _ imag is the imaginary part of the impedance of the lithium ion battery, a is a constant, and n is the number of applied alternating current frequencies.
7. The method according to any one of claims 1-6, wherein the first correspondence satisfies the following formula:
A 1 ＝k×T+b
wherein A is 1 And k and b are constants, and T is the internal temperature of the lithium ion battery.
8. An apparatus for estimating internal temperature of a lithium ion battery, the apparatus comprising:
the acquisition module is used for acquiring a plurality of constant phase element CPE values of the lithium ion battery, which correspond to a plurality of internal temperatures of the lithium ion battery one by one, respectively in a plurality of charge states of the lithium ion battery;
a fitting module, configured to fit the internal temperatures and the CPE values in the multiple charge states to obtain a first corresponding relationship when the internal temperature of the lithium ion battery is less than zero degrees centigrade, where the first corresponding relationship is a linear relationship between the internal temperature of the lithium ion battery and the CPE value of the lithium ion battery;
a first determination module, configured to determine a current constant phase angle element CPE value of the lithium ion battery;
a searching module, configured to search for an internal temperature corresponding to the current CPE value in the first correspondence;
and the second determining module is used for determining the searched internal temperature as the current internal temperature of the lithium ion battery if the searched internal temperature is less than zero degrees centigrade.
9. 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 7.
10. 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 7.
CN202110328363.8A 2021-03-26 2021-03-26 Method and device, medium and equipment for estimating internal temperature of lithium ion battery Pending CN115128463A (en)

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