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

Abstract

The present disclosure relates to a method and apparatus, medium, and device for estimating the internal temperature of a lithium-ion battery. The method includes: obtaining multiple CPE values ​​corresponding to multiple internal temperatures of a lithium-ion battery respectively under multiple charge states of the lithium-ion battery; fitting a first correspondence relationship when the internal temperature of the lithium-ion battery is less than zero degrees Celsius based on multiple internal temperatures and multiple CPE values ​​under multiple charge states, wherein the first correspondence relationship is a linear relationship between the internal temperature of the lithium-ion battery and the CPE value of the lithium-ion battery; determining the current CPE value of the lithium-ion battery; finding the internal temperature corresponding to the current CPE value in the first correspondence relationship; if the internal temperature found is less than zero degrees Celsius, determining the internal temperature found as the current internal temperature of the lithium-ion battery. This solution can more accurately determine the internal temperature of a lithium-ion battery when the temperature is less than zero degrees Celsius, and the solution is simple and the data processing speed is fast.

Description

Technical Field

[0001] The present disclosure relates to the technical field of power battery detection, and in particular, to a method, device, medium, and equipment for estimating the internal temperature of a lithium-ion battery. Background Art

[0002] The internal temperature of the power battery during the charging and discharging process will directly affect the operating performance of the electric vehicle, such as cycle life, efficiency, reliability and safety. Therefore, it is necessary to detect the internal temperature of the power battery in a timely and accurate manner.

[0003] At present, due to technical limitations, temperature sensors cannot be placed inside the battery cell. Under certain operating conditions, the temperature difference between the temperature at the sensor placement location and the actual temperature inside the battery cell can be as high as 10°C or higher. At the same time, the temperature difference changes in real time with the change of the battery's working state, and is not a fixed value. If the temperature inside the battery is inaccurate, it will cause errors in the calculation results such as battery cell charge state estimation and thermal runaway warning. More importantly, the internal temperature of the battery cell will reach the critical point of thermal runaway earlier than the surface temperature, which may lead to thermal runaway and even serious explosion.

[0004] The surface temperature cannot show the thermal behavior of the entire battery, and the core temperature is not easy to measure. Therefore, estimating the internal temperature of the power battery cell, monitoring the safe operation of the battery and preventing thermal runaway are very important and urgent tasks. Existing algorithms for estimating the internal temperature of the battery usually estimate the internal temperature of the battery by establishing a temperature model and fitting the model parameters using an algorithm (offline calibration or online estimation). Summary of the invention

[0005] The purpose of the present disclosure is to provide a method, device, medium, and equipment for estimating the internal temperature of a lithium-ion battery, which can quickly and accurately estimate the internal temperature of a lithium-ion battery.

[0006] In order to achieve the above object, the present disclosure provides a method for estimating the internal temperature of a lithium-ion battery, the method comprising:

[0007] Acquire, respectively under multiple states of charge of the lithium-ion battery, multiple constant phase element CPE values ​​of the lithium-ion battery corresponding to multiple internal temperatures of the lithium-ion battery;

[0008] According to the multiple internal temperatures and the multiple CPE values ​​under the multiple charge states, a first corresponding relationship is obtained by fitting when the internal temperature of the lithium-ion battery is less than zero degrees Celsius, wherein 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;

[0009] Determine the current constant phase angle element CPE value of the lithium-ion battery;

[0010] Finding the internal temperature corresponding to the current CPE value in the first corresponding relationship;

[0011] If the internal temperature found is less than zero degrees Celsius, the internal temperature found is determined as the current internal temperature of the lithium-ion battery.

[0012] Optionally, determining a current CPE value of the lithium-ion battery includes:

[0013] Obtaining a second corresponding relationship 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;

[0014] The current CPE value of the lithium-ion battery is determined according to the second corresponding relationship.

[0015] Optionally, determining a current CPE value of the lithium-ion battery according to the second corresponding relationship includes:

[0016] Determining a third corresponding relationship between the impedance of the lithium-ion battery, the applied alternating current frequency, and the CPE value of the lithium-ion battery;

[0017] According to the second corresponding relationship and the third corresponding relationship, the current CPE value of the lithium-ion battery is calculated by a fitting algorithm.

[0018] Optionally, the third corresponding relationship satisfies the following formula:

[0019]

[0020] Wherein, Z(ω) is a function of the impedance Z of the lithium ion battery changing with the applied alternating current frequency ω, A1 is the CPE value of the lithium ion battery, γ is a correction factor, j is the unit of the imaginary number in the complex number, and R1 and R2 are the resistance values ​​of the resistors connected in series with the CEP in the equivalent circuit model of the lithium ion battery.

[0021] Optionally, calculating the current CPE value of the lithium-ion battery by a fitting algorithm according to the second corresponding relationship and the third corresponding relationship includes:

[0022] Iterative fitting is performed according to the following formula to obtain a CPE value that matches the ideal value of γ as the current CPE value of the lithium-ion battery:

[0023] Z(ω,p)=Z1(ω,p)+j·Z2(ω,p)

[0024] Wherein, Z(ω,p) is a function of the impedance Z of the lithium-ion battery changing with the applied alternating current frequency ω and a parameter group p, the parameters in the parameter group p include γ, A1, R1 and R2, Z1(ω,p) is the real part of Z(ω,p), and Z2(ω,p) is the imaginary part of Z(ω,p).

[0025] 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 used as a current CPE value of the lithium-ion battery:

[0026]

[0027] RMSE(p)<a

[0028] 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.

[0029] Optionally, the first corresponding relationship satisfies the following formula:

[0030] A1=k×T+b

[0031] Wherein, A1 is the CPE value of the lithium-ion battery, k and b are constants, and T is the internal temperature of the lithium-ion battery.

[0032] The present disclosure also provides a device for estimating the internal temperature of a lithium-ion battery, the device comprising:

[0033] An acquisition module, used for acquiring, respectively under multiple states of charge of the lithium-ion battery, a plurality of constant phase element CPE values ​​of the lithium-ion battery corresponding to a plurality of internal temperatures of the lithium-ion battery;

[0034] a fitting module, configured to fit, according to the multiple internal temperatures and the multiple CPE values ​​under the multiple states of charge, a first corresponding relationship when the internal temperature of the lithium-ion battery is less than zero degrees Celsius, wherein 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;

[0035] A first determination module is used to determine the current constant phase angle element CPE value of the lithium-ion battery;

[0036] A search module, used to search for an internal temperature corresponding to the current CPE value in the first corresponding relationship;

[0037] The second determination module is used 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 Celsius.

[0038] The present disclosure also provides a computer-readable storage medium on which a computer program is stored. When the program is executed by a processor, the steps of the above method provided by the present disclosure are implemented.

[0039] The present disclosure also provides an electronic device, comprising:

[0040] a memory having a computer program stored thereon;

[0041] A processor is used to execute the computer program in the memory to implement the steps of the above method provided by the present disclosure.

[0042] Through the above technical solution, multiple internal temperatures of the lithium-ion battery and multiple CPE values ​​corresponding to each other are obtained under multiple charge states of the lithium-ion battery, and then the first corresponding relationship between the internal temperature and the CPE value is obtained by fitting when the internal temperature of the lithium-ion battery is less than zero degrees Celsius. In this way, the current CPE value of the lithium-ion battery can be used to directly search in the first corresponding relationship. Since the CPE value of the lithium-ion battery and the internal temperature of the lithium ion have a relatively stable linear relationship when it is less than zero degrees Celsius, and are basically unrelated to the SOC, when it is less than zero degrees Celsius, the SOC can be ignored, and the internal temperature of the lithium-ion battery can be directly estimated by the CPE value reflecting the characteristics of the lithium-ion battery itself, thereby more accurately determining the internal temperature of the lithium-ion battery, and the solution is simple and has a fast data processing speed.

[0043] Other features and advantages of the present disclosure will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] The accompanying drawings are used to provide a further understanding of the present disclosure and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present disclosure but do not constitute a limitation of the present disclosure. In the accompanying drawings:

[0045] Figure 1 is a flow chart of a method for estimating the internal temperature of a lithium-ion battery provided by an exemplary embodiment;

[0046] Figure 2 is a graph of an exemplary embodiment providing an estimate of the internal temperature of a lithium-ion battery as a function of SOC and CPE values;

[0047] Figure 3 is an equivalent circuit diagram of an estimated lithium-ion battery provided by an exemplary embodiment;

[0048] Figure 4 is a block diagram of an apparatus for estimating the internal temperature of a lithium-ion battery provided by an exemplary embodiment;

[0049] Figure 5It is a block diagram of an electronic device shown in an exemplary embodiment. DETAILED DESCRIPTION

[0050] The specific implementation of the present disclosure is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described herein is only used to illustrate and explain the present disclosure, and is not used to limit the present disclosure.

[0051] When the internal temperature of a lithium-ion battery is below zero degrees Celsius, the value of the constant phase angle element (CPE) in the lower frequency range is basically unrelated to the battery's state of charge (SOC), while the CPE value has a relatively stable linear relationship with the lithium-ion internal temperature. Therefore, in the scheme disclosed herein, when the internal temperature of a lithium-ion battery is below zero degrees Celsius, the SOC is ignored, and the internal temperature of the lithium-ion battery is directly estimated by the CPE value that reflects the characteristics of the lithium-ion battery itself, so that the internal temperature of the lithium-ion battery can be determined more accurately.

[0052] Figure 1 FIG. 1 is a flow chart of a method for estimating the internal temperature of a lithium-ion battery provided by an exemplary embodiment. Figure 1 As shown, the method may include the following steps.

[0053] Step S11 , obtaining a plurality of CPE values ​​of the lithium-ion battery corresponding to a plurality of internal temperatures of the lithium-ion battery at a plurality of SOCs of the lithium-ion battery respectively.

[0054] Step S12, fitting a first corresponding relationship when the internal temperature of the lithium-ion battery is less than zero degrees Celsius according to multiple internal temperatures and multiple CPE values ​​under multiple SOCs, wherein 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.

[0055] Step S13, determining the current CPE value of the lithium-ion battery.

[0056] Step S14, searching the first corresponding relationship for the internal temperature corresponding to the current CPE value.

[0057] Step S15: If the internal temperature is less than zero degrees Celsius, the internal temperature is determined as the current internal temperature of the lithium-ion battery.

[0058] In step S11 , multiple data pairs of internal temperature and CPE value can be obtained at multiple SOCs by experiment and plotted into a curve graph. Figure 2 FIG. 1 is a graph showing the estimated internal temperature of a lithium-ion battery as a function of SOC and CPE values, provided by an exemplary embodiment. Figure 2As shown, the three curves represent the relationship between the CPE value and the battery internal temperature T when the SOC is 0.25, 0.5 and 0.75 respectively. It can be seen that when the internal temperature is below zero degrees Celsius, the battery internal temperature T is basically unrelated to the SOC, but has a stable linear relationship with the CPE value. In this solution, an equation for the linear relationship (first corresponding relationship) between the battery internal temperature T and the CPE value can be established, and then the parameters in the equation can be determined by fitting.

[0059] The current CPE value of the lithium-ion battery can be obtained according to the method in the relevant technology. The first correspondence can be calibrated in advance by an experimental method and then stored. If the current CPE value of the lithium-ion battery has been obtained, it is easy to obtain the corresponding current internal temperature of the lithium-ion battery by looking up the table in the first correspondence, and when the internal temperature is less than zero degrees Celsius, it can be determined as the current internal temperature. Otherwise, when the internal temperature of the lithium-ion battery is greater than zero degrees Celsius, the SOC will affect the linear relationship between the internal temperature and the CPE value. Therefore, it can be considered that the internal temperature found is not accurate. At this time, other methods can be used to determine the internal temperature of the lithium-ion battery.

[0060] Through the above technical solution, multiple internal temperatures of the lithium-ion battery and multiple CPE values ​​corresponding to each other are obtained under multiple charge states of the lithium-ion battery, and then the first corresponding relationship between the internal temperature and the CPE value is obtained by fitting when the internal temperature of the lithium-ion battery is less than zero degrees Celsius. In this way, the current CPE value of the lithium-ion battery can be used to directly search in the first corresponding relationship. Since the CPE value of the lithium-ion battery and the internal temperature of the lithium ion have a relatively stable linear relationship when it is less than zero degrees Celsius, and are basically unrelated to the SOC, when it is less than zero degrees Celsius, the SOC can be ignored, and the internal temperature of the lithium-ion battery can be directly estimated by the CPE value reflecting the characteristics of the lithium-ion battery itself, thereby more accurately determining the internal temperature of the lithium-ion battery, and the solution is simple and has a fast data processing speed.

[0061] In yet another embodiment, Figure 1 Based on the above, determining the current CPE value of the lithium-ion battery (step S13) may include: obtaining a second correspondence between the impedance of the lithium-ion battery and the frequency of the applied alternating current by an electrochemical impedance spectroscopy (EIS) method. 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 correspondence.

[0062] In the EIS method, a small amplitude AC potential wave with different frequencies is applied to the electrochemical system, and the ratio of the AC potential to the current signal (i.e., the impedance of the system) is measured as the frequency of the sine wave changes. The second corresponding relationship mentioned above is the relationship between the impedance of the lithium-ion battery and the applied AC frequency when the applied AC frequency is less than a predetermined frequency threshold, obtained by the EIS method.

[0063] For example, during the charging process of an electric vehicle connected to a charging pile, a charging current signal less than a predetermined frequency threshold (for example, less than 0.1Hz, preferably 0.01Hz to 0.1Hz) is sent to the electric vehicle by the charging pile. At this time, the battery management system (BMS) synchronously samples the current signal and voltage signal of the battery and records the current signal and voltage signal. The sampled current and voltage are Fourier transformed to obtain the amplitude and phase information of the internal resistance of the battery at the corresponding frequency, that is, the second corresponding relationship; during the discharge process, that is, during the normal driving of the electric vehicle, the current signal and voltage signal of the battery are synchronously sampled, and the current signal and voltage signal are recorded. Subsequently, the sampled current and voltage are Fourier expanded, and the mixed signal frequency can be decomposed into a sine superposition of multiple frequencies. Subsequently, a fast Fourier transform is performed, and the effective signal of the effective frequency is screened out, and the amplitude and phase information of the resistance with a frequency of (0.01Hz to 0.1Hz) is obtained, that is, the second corresponding relationship.

[0064] In this embodiment, the impedance characteristics of the lithium-ion battery determined by the EIS method are used to determine the current CPE value, which has high accuracy.

[0065] In another embodiment, the above-mentioned determination of the current CPE value of the lithium-ion battery based on the second correspondence may include: determining a third correspondence between 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 based on the second correspondence and the third correspondence.

[0066] The third corresponding relationship can be determined according to the relationship among the impedance of the lithium-ion battery, the frequency of the applied alternating current, and the CPE value of the lithium-ion battery in the related art. For example, ZVIEW software can be used for fitting.

[0067] In this 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.

[0068] The equivalent circuit of a lithium-ion battery can be simplified to be similar to a first-order RC circuit. Figure 3FIG. 1 is an equivalent circuit diagram of a lithium-ion battery provided by an exemplary embodiment. Figure 3 As shown, the equivalent circuit includes a resistor R1, a resistor R2, a first CPE A1 and a second CPE A2. 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 this solution is implemented at a relatively low frequency (less than a predetermined frequency threshold), the second CPE A2 can be ignored, and the first CPE A1 is the CPE of the lithium-ion battery.

[0069] exist Figure 3 Based on the equivalent circuit, at low frequency, the third corresponding relationship can satisfy the following formula:

[0070]

[0071] Wherein, Z(ω) is a function of the impedance Z of the lithium-ion battery changing with the applied alternating current frequency ω, A1 is the CPE value of the lithium-ion battery (the value of the first CEP1), γ is a correction factor (the fractional order of CEP), j is the unit of the imaginary number in the complex number, and R1 and R2 are 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.

[0072] The impedance of the equivalent circuit can be written separately into two terms, the real part and the imaginary part, depending on different frequencies ω and different parameter sets p. In another embodiment, the current CPE value of the lithium-ion battery under the applied alternating current frequency is calculated by a fitting algorithm based on the second corresponding relationship and the third corresponding relationship, which may include:

[0073] Perform iterative fitting according to the following formula to obtain the CPE value that matches the ideal value of γ as the current CPE value of the lithium-ion battery:

[0074] Z(ω,p)=Z1(ω,p)+j·Z2(ω,p) (2)

[0075] Wherein, Z(ω,p) is a function of the impedance Z of the lithium-ion battery varying with the applied alternating current frequency ω and the parameter group p, the parameters in the parameter group p include γ, A1, R1 and R2, Z1(ω,p) is the real part of Z(ω,p), and Z2(ω,p) is the imaginary part of Z(ω,p).

[0076] In formula (2), γ, A1, R1 and R2 are used as a set of parameters. In the test, the amplitude and phase information of the impedance of the lithium-ion battery can be converted into the values ​​of the real and imaginary parts of the impedance. On this basis, fitting is performed according to the relevant algorithm to obtain the optimal parameter solution in the formula.

[0077] In this embodiment, the impedance is written in the form of a real part and an imaginary part, and fitting is performed using the values ​​of the real part and the imaginary part, which has a high accuracy.

[0078] 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:

[0079]

[0080] Where 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 AC frequencies, ω i is the i-th alternating current frequency from 1 to n.

[0081] In formula (3), the root mean square error RMSE(p) is made smaller than the constant a through an iterative fitting algorithm, and the optimal parameter solution is obtained. In this embodiment, fitting is performed based on the root mean square error, the steps are simple and the accuracy of the result is high.

[0082] In one embodiment, the first corresponding relationship may satisfy the following formula:

[0083] A1=k×T+b (4)

[0084] Among them, A1 is the CPE value of the lithium-ion battery, k and b are constants, and T is the internal temperature of the lithium-ion battery.

[0085] The parameters k and b can be determined in advance through experiments so that the battery internal temperature T and the CPE value have a certain relationship. In this way, the internal temperature of the lithium-ion battery can be directly calculated by knowing the current CPE value of the lithium-ion battery.

[0086] In this embodiment, the linear relationship between the CPE value and the internal temperature of the lithium-ion battery is obtained by pre-fitting, the result is accurate, the calculation method is simple, and the processing speed is fast.

[0087] Figure 4 FIG. 1 is a block diagram of an apparatus for estimating the internal temperature of a lithium-ion battery provided by an exemplary embodiment. Figure 4 As shown, the apparatus 400 for estimating the internal temperature of a lithium-ion battery may include an acquisition module 401 , a fitting module 402 , a first determination module 403 , a search module 404 , and a second determination module 405 .

[0088] The acquisition module 401 is used to acquire a plurality of CPE values ​​of the lithium-ion battery corresponding to a plurality of internal temperatures of the lithium-ion battery at a plurality of SOCs of the lithium-ion battery respectively;

[0089] The fitting module 402 is used to fit a first corresponding relationship when the internal temperature of the lithium-ion battery is less than zero degrees Celsius according to multiple internal temperatures and multiple CPE values ​​under multiple SOCs, wherein 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;

[0090] The first determination module 403 is used to determine the current CPE value of the lithium-ion battery.

[0091] The search module 404 is used to search for the internal temperature corresponding to the current CPE value in the first corresponding relationship.

[0092] The second determination module 405 is used 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 Celsius.

[0093] Optionally, the first determination module 403 may include an acquisition submodule and a first determination submodule.

[0094] The acquisition submodule is used to acquire a second corresponding relationship between the impedance of the lithium-ion battery and the applied alternating current frequency by an EIS method, wherein the applied alternating current frequency is less than a predetermined frequency threshold;

[0095] The first determining submodule is used to determine the current CPE value of the lithium-ion battery according to the second corresponding relationship.

[0096] Optionally, the first determining submodule may include a second determining submodule and a calculating submodule.

[0097] The second determination submodule is used to determine a third corresponding relationship among the impedance of the lithium-ion battery, the frequency of the applied alternating current, and the CPE value of the lithium-ion battery.

[0098] The calculation submodule is used to calculate the current CPE value of the lithium-ion battery through a fitting algorithm according to the second corresponding relationship and the third corresponding relationship.

[0099] Optionally, the third corresponding relationship satisfies the following formula:

[0100]

[0101] Wherein, Z(ω) is a function of the impedance Z of the lithium-ion battery changing with the applied alternating current frequency ω, A1 is the CPE value of the lithium-ion battery, γ is a correction factor, j is the unit of the imaginary number in the complex number, and R1 and R2 are the resistance values ​​of the resistors connected in series with the CEP in the equivalent circuit model of the lithium-ion battery.

[0102] Optionally, the calculation submodule may include an iteration submodule.

[0103] The iterative submodule is used to perform iterative fitting according to the following formula to obtain a CPE value that matches the ideal value of γ under the applied AC frequency as the current CPE value of the lithium-ion battery:

[0104] Z(ω,p)=Z1(ω,p)+j·Z2(ω,p)

[0105] Wherein, Z(ω,p) is a function of the impedance Z of the lithium-ion battery varying with the applied alternating current frequency ω and the parameter group p, the parameters in the parameter group p include γ, A1, R1 and R2, Z1(ω,p) is the real part of Z(ω,p), and Z2(ω,p) is the imaginary part of Z(ω,p).

[0106] 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 used as the current CPE value of the lithium-ion battery:

[0107]

[0108] RMSE(p)<a

[0109] 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.

[0110] Optionally, the first corresponding relationship satisfies the following formula:

[0111] A1=k×T+b

[0112] Among them, A1 is the CPE value of the lithium-ion battery, k and b are constants, and T is the internal temperature of the lithium-ion battery.

[0113] Regarding the device in the above embodiment, the specific manner in which each module performs operations has been described in detail in the embodiment of the method, and will not be elaborated here.

[0114] Through the above technical solution, multiple internal temperatures of the lithium-ion battery and multiple CPE values ​​corresponding to each other are obtained under multiple charge states of the lithium-ion battery, and then the first corresponding relationship between the internal temperature and the CPE value is obtained by fitting when the internal temperature of the lithium-ion battery is less than zero degrees Celsius. In this way, the current CPE value of the lithium-ion battery can be used to directly search in the first corresponding relationship. Since the CPE value of the lithium-ion battery and the internal temperature of the lithium ion have a relatively stable linear relationship when it is less than zero degrees Celsius, and are basically unrelated to the SOC, when it is less than zero degrees Celsius, the SOC can be ignored, and the internal temperature of the lithium-ion battery can be directly estimated by the CPE value reflecting the characteristics of the lithium-ion battery itself, thereby more accurately determining the internal temperature of the lithium-ion battery, and the solution is simple and has a fast data processing speed.

[0115] The present disclosure also provides an electronic device, including a memory and a processor.

[0116] A computer program is stored in the memory; the processor is used to execute the computer program in the memory to implement the steps of the above method provided by the present disclosure.

[0117] Figure 5 FIG. 5 is a block diagram of an electronic device 500 according to an exemplary embodiment. Figure 5 As shown, 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.

[0118] The processor 501 is used to control the overall operation of the electronic device 500 to complete all or part of the steps in the above-mentioned method for estimating the internal temperature of the lithium-ion battery. The memory 502 is used to store various types of data to support the operation of the electronic device 500, and these data may include, for example, instructions for any application or method used to operate on the electronic device 500, and application-related data, such as contact data, sent and received messages, pictures, audio, video, etc. The memory 502 can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as static random access memory (Static Random Access Memory, referred to as SRAM), electrically erasable programmable read-only memory (Electrically Erasable Programmable Read-Only Memory, referred to as EEPROM), erasable programmable read-only memory (Erasable Programmable Read-Only Memory, referred to as EPROM), programmable read-only memory (Programmable Read-Only Memory, referred to as PROM), read-only memory (Read-Only Memory, referred to as ROM), magnetic memory, flash memory, magnetic disk or optical disk. The multimedia component 503 may include a screen and an audio component. The screen may be, for example, a touch screen, and the audio component is used to output and / or input audio signals. For example, the audio component may include a microphone for receiving external audio signals. The received audio signal may be further stored in the memory 502 or sent through the communication component 505. The audio component 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, and the above-mentioned other interface modules may be keyboards, mice, buttons, etc. 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, is not limited here. Therefore, the corresponding communication component 505 may include: Wi-Fi module, Bluetooth module, NFC module, etc.

[0119] In an exemplary embodiment, the electronic device 500 may be implemented by one or more application specific integrated circuits (ASIC), digital signal processors (DSP), digital signal processing devices (DSPD), programmable logic devices (PLD), field programmable gate arrays (FPGA), controllers, microcontrollers, microprocessors or other electronic components to perform the above-mentioned method for estimating the internal temperature of a lithium-ion battery.

[0120] In another exemplary embodiment, a computer-readable storage medium including program instructions is also provided, and when the program instructions are executed by a processor, the steps of the above-mentioned method for estimating the internal temperature of a lithium-ion battery are implemented. For example, the computer-readable storage medium may be the above-mentioned memory 502 including program instructions, and the above-mentioned program instructions may be executed by the processor 501 of the electronic device 500 to complete the above-mentioned method for estimating the internal temperature of a lithium-ion battery.

[0121] The preferred embodiments of the present disclosure are described in detail above in conjunction with the accompanying drawings; however, the present disclosure is not limited to the specific details in the above embodiments. Within the technical concept of the present disclosure, a variety of simple modifications can be made to the technical solution of the present disclosure, and these simple modifications all fall within the protection scope of the present disclosure.

[0122] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present disclosure will not further describe various possible combinations.

[0123] In addition, various embodiments of the present disclosure may be arbitrarily combined, and as long as they do not violate the concept of the present disclosure, they should also be regarded as the contents disclosed by the present disclosure.

Claims

1. A method for estimating the internal temperature of a lithium-ion battery, characterized in that: The method comprises: Acquire, respectively under multiple states of charge of the lithium-ion battery, multiple constant phase angle element CPE values ​​of the lithium-ion battery corresponding to multiple internal temperatures of the lithium-ion battery; According to the multiple internal temperatures and the multiple CPE values ​​under the multiple charge states, a first corresponding relationship is obtained by fitting when the internal temperature of the lithium-ion battery is less than zero degrees Celsius, wherein 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; Determining a current CPE value of the lithium-ion battery; Finding the internal temperature corresponding to the current CPE value in the first corresponding relationship; If the internal temperature is less than zero degrees Celsius, the internal temperature is determined as the current internal temperature of the lithium-ion battery; The first corresponding relationship satisfies the following formula: in, is the CPE value of the lithium-ion battery, is a constant, is the internal temperature of the lithium-ion battery.

2. The method according to claim 1, characterized in that Determining a current CPE value of the lithium-ion battery includes: Obtaining a second corresponding relationship 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; The current CPE value of the lithium-ion battery is determined according to the second corresponding relationship.

3. The method according to claim 2, characterized in that The determining the current CPE value of the lithium-ion battery according to the second corresponding relationship includes: Determining a third corresponding relationship between the impedance of the lithium-ion battery, the applied alternating current frequency, and the CPE value of the lithium-ion battery; According to the second corresponding relationship and the third corresponding relationship, the current CPE value of the lithium-ion battery is calculated by a fitting algorithm.

4. The method according to claim 3, characterized in that The third corresponding relationship satisfies the following formula: in, is the impedance of the lithium-ion battery As the applied AC frequency The function of change, is the CPE value of the lithium-ion battery, is the correction factor, is the unit of the imaginary number in complex numbers, is the resistance value of the resistor connected in series with the CEP in the equivalent circuit model of the lithium ion battery.

5. The method according to claim 4, characterized in that The calculating the current CPE value of the lithium-ion battery by a fitting algorithm according to the second corresponding relationship and the third corresponding relationship includes: According to the following formula, iterative fitting is performed to obtain The CPE value that matches the ideal value is used as the current CPE value of the lithium-ion battery: in, is the impedance of the lithium-ion battery As the applied AC frequency and parameter groups The parameter set The parameters in include , , , for The real part of for The imaginary part of .

6. The method according to claim 5, characterized in that In the iterative fitting, the parameter group corresponding to the impedance of the lithium-ion battery that satisfies the following formula is The CPE value in is used as the current CPE value of the lithium-ion battery: in, is the real part of the impedance of the lithium-ion battery, is the imaginary part of the impedance of the lithium-ion battery, is a constant, is the number of frequencies of the applied alternating current.

7. A device for estimating the internal temperature of a lithium-ion battery, characterized in that: The device comprises: An acquisition module, used for acquiring, respectively under multiple states of charge of the lithium-ion battery, a plurality of constant phase angle element CPE values ​​of the lithium-ion battery corresponding to a plurality of internal temperatures of the lithium-ion battery; a fitting module, configured to fit, according to the multiple internal temperatures and the multiple CPE values ​​under the multiple states of charge, a first corresponding relationship when the internal temperature of the lithium-ion battery is less than zero degrees Celsius, wherein 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, used to determine the current CPE value of the lithium-ion battery; A search module, configured to search the first corresponding relationship for an internal temperature corresponding to the current CPE value; a second determination module, configured to determine the internal temperature to be the current internal temperature of the lithium-ion battery if the internal temperature is less than zero degrees Celsius; The first corresponding relationship satisfies the following formula: in, is the CPE value of the lithium-ion battery, is a constant, is the internal temperature of the lithium-ion battery.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the steps of the method described in any one of claims 1 to 6 are implemented.

9. An electronic device, characterized in that: include: a memory having a computer program stored thereon; A processor, configured to execute the computer program in the memory to implement the steps of the method according to any one of claims 1 to 6.

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