Lithium ion battery alternating current heating method in driving state

Abstract

The invention relates to a lithium ion battery alternating current heating method in a driving state, which belongs to the technical field of batteries, and comprises the following steps: S1, selecting a battery, and obtaining related battery parameters through an HPPC experiment and an alternating current impedance test; s2, updating equivalent circuit model parameters in real time according to the SOC and the temperature of the battery; s3, acquiring excitation current in a current driving state, and calculating cutoff voltage and maximum alternating current heating current amplitudes of different frequencies under the constraint of the lithium precipitation model by combining model parameters; s4, calculating heat production rates under the maximum alternating current heating current amplitudes of different frequencies based on a frequency domain thermal model; and S5, updating the optimal current amplitude and frequency in real time until the battery temperature reaches the target temperature.

Description

Technical Field

[0001] The invention belongs to the technical field of batteries and relates to an AC heating method for a lithium-ion battery in a driving state. Background Art

[0002] With the continued expansion of the new energy vehicle industry, lithium-ion batteries, as the core power source of electric vehicles, are attracting increasing research attention to optimize their comprehensive performance. Ambient temperature has a significant impact on the overall performance of lithium-ion batteries, especially at low temperatures, where discharge is hindered, discharge efficiency is reduced, and cycle life is shortened. Therefore, implementing effective heating measures for lithium-ion batteries under low-temperature conditions to ensure stable operation within the ideal temperature range is crucial for significantly improving their overall performance in low-temperature environments.

[0003] Current low-temperature battery heating technologies can be categorized as external heating and internal heating. External heating primarily utilizes heat sources external to the battery pack, such as phase change materials, thermal fluids, and electric heating elements, to heat the battery via heat conduction and convection. However, this external heating method suffers from low heating efficiency, uneven temperature distribution, and a slow temperature rise rate. In contrast, internal heating relies on the battery's own internal impedance to generate heat. Given the increased internal resistance of lithium-ion batteries at low temperatures, this heating method can achieve higher heating efficiency, better temperature uniformity, and a faster temperature rise rate. However, current internal AC heating technologies for lithium-ion batteries mostly utilize fixed amplitude or frequency modes, making it difficult to achieve a higher temperature rise rate. Furthermore, current AC heating technologies only operate while the vehicle is parked, meaning no other current is excited during the AC heating process. Therefore, AC heating applications while driving have not yet been implemented.

[0004] Based on the above defects, there is an urgent need for an AC heating strategy that can be updated in real time according to the battery's current temperature and state of charge, as well as the current excitation under driving conditions, to achieve efficient and rapid temperature rise of the power battery under driving conditions. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide a lithium-ion battery AC heating method under driving conditions, which can achieve rapid heating of the lithium-ion battery during driving in a low-temperature environment while ensuring that the terminal voltage of the lithium-ion battery does not exceed its upper and lower cut-off voltages and does not cause lithium deposition.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] A method for AC heating of a lithium-ion battery in a driving state comprises the following steps:

[0008] S1: Select the battery and obtain relevant battery parameters through HPPC experiment and AC impedance test;

[0009] S2: Update the equivalent circuit model parameters in real time according to the battery SOC and temperature;

[0010] S3: Obtain the excitation current under the current driving state, and calculate the maximum AC heating current amplitude of different frequencies under the constraints of the cutoff voltage and lithium plating model based on the model parameters;

[0011] S4: Calculate the heat generation rate at the maximum AC heating current amplitude at different frequencies based on the frequency domain thermal model;

[0012] S5: Update the optimal current amplitude and frequency in real time until the battery temperature reaches the target temperature.

[0013] Furthermore, step S1 specifically includes the following steps:

[0014] S11: Perform HPPC tests at different SOC states at different temperatures to obtain DC internal resistance data of lithium-ion batteries;

[0015] S12: Perform EIS tests at different SOC states at different temperatures to obtain AC impedance data of the lithium-ion battery;

[0016] S13: Obtaining the open circuit voltage of the lithium-ion battery at different SOC states;

[0017] S14: Obtain the specific heat capacity of the lithium-ion battery and the convection heat transfer coefficient under the current environment.

[0018] Furthermore, step S2 specifically includes the following steps:

[0019] S21: Obtain the DC internal resistance at different temperatures and SOC states through offline parameter identification of HPPC experimental data;

[0020] S22: Fitting the battery impedance spectrum obtained from the battery EIS test to obtain the component parameters of the fractional-order model at different temperatures and different SOC states;

[0021] S23: Obtain the SOC-OCV fitting equation through the polynomial fitting method.

[0022] Furthermore, step S3 specifically includes the following steps:

[0023] S31: Obtain the vehicle's driving speed within the next second and calculate the maximum battery discharge current I within the next second dc,max With the minimum value I dc,min ;

[0024] S32: Calculate the battery terminal voltage response under driving current excitation based on the Rint model. The calculation formula is:

[0025] U=U ocv (SOC)-I dc *R dc (SOC,T)

[0026] Where U is the terminal voltage response of the battery under DC current excitation, U ocv (SOC) is the polynomial response model of the battery open circuit voltage with respect to SOC, I dc is the maximum or minimum value of the driving excitation current within this second, R dc (SOC, T) is the lookup table response of the battery's DC internal resistance with respect to SOC and temperature;

[0027] S33: Calculate the battery terminal voltage response under AC / DC coupling based on the fractional-order model. The calculation formula is:

[0028] U total =U+I ac *|Z total |

[0029] Among them U total is the battery terminal voltage under AC / DC coupling excitation, I ac is the AC current amplitude, Z total is the total battery impedance in the fractional-order model;

[0030] S34: Calculate the maximum AC heating current amplitude based on the battery upper and lower cutoff voltage constraints:

[0031] UU min ≤I ac,v |Z total |≤U max -U

[0032] Among them U min is the battery cut-off voltage, U max is the battery cut-off voltage, I ac,v is the maximum AC heating current amplitude calculated based on the cut-off voltage constraint;

[0033] S35: Establish a lithium deposition model and calculate the maximum AC heating current amplitude based on the constraints of the lithium deposition model:

[0034] (I ac,ct +I dc )|Z ct |≤U n,ocv

[0035] where Z ct is the charge transfer impedance, U n,ocvis the negative electrode equilibrium potential of the battery at this SOC state, I ac,ct is the maximum AC heating current amplitude obtained based on the constraints of the lithium plating model;

[0036] S36: Take I ac,v , I ac,ct The smaller value is the maximum AC current amplitude allowed for a certain frequency in the current state;

[0037] S37: Traverse the maximum AC current amplitude allowed at different frequencies.

[0038] Furthermore, in step S4, a heat generation model based on the frequency domain is established, and the heat generation model calculation formula in the thermal model is:

[0039]

[0040] Among them, Q total is the total heat production, Q dc The heat generated by the DC current, that is, the heat generated by the driving current excitation, is calculated by the DC internal resistance. ac The heat generated by AC current, that is, the heat generated by the current used for AC heating, is calculated through AC impedance;

[0041] The heat dissipation model calculation formula in the thermal model is:

[0042] Q c =hA(TT f )

[0043] Where h is the convective heat transfer coefficient, A is the surface area, T f is the ambient temperature;

[0044] According to the law of conservation of energy, a thermal model of the battery is established to describe the temperature change of the battery itself. The expression is as follows:

[0045]

[0046] Where m is the mass of the battery, c is the specific heat capacity of the battery;

[0047] Through the battery frequency domain thermal model and the maximum AC current amplitude allowed at different frequencies, the heat generation rate at the maximum AC heating current amplitude at different frequencies is obtained when the driving excitation current is 0.

[0048] Furthermore, in step S5, based on the AC current amplitude and frequency corresponding to the maximum heat generation rate in each frequency obtained in step S4, the battery is AC-heated using the optimal AC parameters and updated in real time until the battery temperature reaches the target temperature.

[0049] The beneficial effects of the present invention are:

[0050] (1) Compared with traditional external heating methods, heating the battery with sinusoidal alternating current can achieve higher heating efficiency, better temperature uniformity and faster temperature rise rate.

[0051] (2) Based on the battery equivalent circuit model parameters at different temperatures and different states of charge, the AC current amplitude and frequency corresponding to the maximum heat generation rate are calculated under the constraints of the upper and lower cut-off voltages and the lithium deposition model, so as to achieve rapid heating of the battery without overpressure or lithium deposition.

[0052] (3) The AC heating parameters can be updated in real time according to the driving current excitation, battery temperature and state of charge while the vehicle is in motion.

[0053] Other advantages, objects, and features of the present invention will be described in part in the following description and, in part, will be apparent to those skilled in the art upon examination of the following description or may be learned from practice of the present invention. The objects and other advantages of the present invention may be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below with reference to the accompanying drawings, in which:

[0055] Figure 1 This is a flow chart of the AC heating method for lithium-ion batteries in a driving state according to the present invention;

[0056] Figure 2 This is a schematic diagram of identifying the DC internal resistance parameters in step S21 of an embodiment of the present invention;

[0057] Figure 3 This is a schematic diagram of AC impedance parameter identification in step S22 of an embodiment of the present invention;

[0058] Figure 4 A parameter transfer path diagram in the heating process corresponding to the present invention;

[0059] Figure 5 The maximum AC heating current amplitude and heat generation rate of the battery at different frequencies calculated in an example of the present invention, where (a) is the current amplitude and (b) is the heat generation rate;

[0060] Figure 6 The figure shows the changes in parameters related to the battery heating process in an example of the present invention, where (a) is the driving current excitation, (b) is the battery temperature, (c) is the AC heating current frequency, and (d) is the AC heating current amplitude.

[0061] Figure 7The figure shows the voltage change during the battery heating process in an example of the present invention. DETAILED DESCRIPTION

[0062] The following describes the embodiments of the present invention by means of specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present invention, and the following embodiments and features in the embodiments can be combined with each other without conflict.

[0063] It should be noted that the illustrations provided in the following embodiments are merely schematic illustrations of the basic concept of the present invention. Therefore, the illustrations only show components related to the present invention and are not drawn according to the number, shape, and size of components in actual implementation. In actual implementation, the type, quantity, and proportion of each component may be changed arbitrarily, and the component layout may also be more complex.

[0064] In the following description, numerous details are discussed to provide a more thorough explanation of the embodiments of the present invention. However, it will be apparent to those skilled in the art that the embodiments of the present invention may be practiced without these specific details. In other embodiments, well-known structures and devices are shown in block diagram form rather than in detail to avoid obscuring the embodiments of the present invention.

[0065] Example 1:

[0066] like Figure 1 As shown, the present invention provides a method for AC heating of a lithium-ion battery in a driving state, comprising the following steps:

[0067] S1: Select a battery and obtain relevant battery parameters through HPPC experiments and AC impedance tests; specifically, the following steps are included:

[0068] S11: Obtain the DC internal resistance data of the lithium-ion battery by performing HPPC tests at different SOC states (SOC=90%, SOC=70%, SOC=50%, SOC=30%, SOC=10%) at different temperatures (-15°C, -10°C, -5°C, 0°C).

[0069] S12: Acquire the AC impedance data of the lithium-ion battery by performing EIS tests at different SOC states (SOC=90%, SOC=70%, SOC=50%, SOC=30%, SOC=10%) at different temperatures (-15°C, -10°C, -5°C, 0°C).

[0070] S13: Obtain the open circuit voltage of the lithium-ion battery at different SOC states.

[0071] S14: Obtain the specific heat capacity of the lithium-ion battery and the convection heat transfer coefficient under the current environment.

[0072] In this embodiment, the selected battery is a Guoxuan High-tech brand lithium iron phosphate battery with a capacity of 102Ah.

[0073] S2: Update the equivalent circuit model parameters in real time based on the battery SOC and temperature; specifically, the following steps are included:

[0074] S21: Through offline parameter identification of HPPC experimental data, the DC internal resistance at different temperatures and different SOC states is obtained.

[0075] Among them, the calculation formula of the DC internal resistance of the HPPC test is:

[0076]

[0077] Among them, R dc is the DC internal resistance, V1 is the terminal voltage before applying the pulse current, V2 is the terminal voltage at the end of the discharge pulse, and I' is the pulse current. Figure 2 As shown, the DC internal resistance values ​​at different states of charge at -15°C to 0°C are calculated. Subsequently, the DC internal resistance value of the lithium-ion battery in the current state can be obtained in real time through a polynomial fitting model as a parameter of the Rint model;

[0078] S22: Fit the battery impedance spectrum obtained by the battery EIS test using Zview software, such as Figure 3 As shown in the figure, the component parameters of the fractional-order model at different temperatures and different SOC states are obtained. Subsequently, the parameter values ​​of the current state of the fractional-order model components can be obtained in real time by using the table lookup method.

[0079] S23: A fitting equation of SOC-OCV is obtained by a polynomial fitting method, and then the current state of charge of the battery is obtained by an ampere-hour integration module. The open circuit voltage of the battery is then obtained by the polynomial model as a parameter of the Rint model.

[0080] S3: Obtain the excitation current under the current driving state, and calculate the maximum AC heating current amplitude of different frequencies under the constraints of the cut-off voltage and lithium plating model in combination with the model parameters; specifically, the following steps are included:

[0081] S31: Obtain the vehicle's speed in the next second through the speed prediction module of the intelligent driving, and then calculate the maximum battery discharge current I in the next second dc,max With the minimum value I dc,min ;

[0082] S32: Calculate the battery terminal voltage response under driving current excitation based on the Rint model. The calculation formula is:

[0083] U=U ocv (SOC)-I dc *R dc (SOC,T)

[0084] Where U is the terminal voltage response of the battery under DC current excitation, U ocv (SOC) is the polynomial response model of the battery open circuit voltage with respect to SOC, I dc is the maximum or minimum value of the driving excitation current within this second, R dc (SOC,T) is the polynomial model response of the battery DC internal resistance with respect to SOC and temperature.

[0085] S33: Calculate the battery terminal voltage response under AC / DC coupling based on the fractional-order model. The calculation formula is:

[0086] U total =U+I ac *|Z total |

[0087] Among them U total is the battery terminal voltage under AC / DC coupling excitation, I ac is the AC current amplitude, Z total is the total battery impedance in the fractional-order model, which is calculated as follows:

[0088]

[0089] where R o is the ohmic internal resistance in the fractional-order model, R ct is the charge transfer resistance in the fractional-order model, n dl,FOM is the exponential parameter of the CPE element in the fractional-order model, C dl,FOM is the coefficient parameter of the CPE element in the fractional-order model, L is the inductance in the fractional-order model, and the above five parameters can all be obtained by the table lookup method in S22.

[0090] S34: Calculate the maximum AC heating current amplitude based on the battery upper and lower cutoff voltage constraints:

[0091] UU min ≤I ac,v |Z total |≤U max -U

[0092] Among them U min is the battery cut-off voltage, U max is the battery cut-off voltage, Iac,v is the maximum AC heating current amplitude calculated based on the upper and lower cutoff voltage constraints.

[0093] S35: Establish a lithium deposition model. During AC heating, to prevent lithium deposition from occurring at the graphite negative electrode of the battery, the difference between the solid-phase potential and the liquid-phase potential of the negative electrode should be greater than the lithium deposition reaction potential. Through derivation and linearization of the Butler-Volmer equation, the lithium deposition criterion can ultimately be expressed as the voltage across the charge transfer resistor being less than the equilibrium potential of the negative electrode, i.e.:

[0094] U ct n,ocv

[0095] Based on the constraints of the lithium plating model, calculate the maximum AC heating current amplitude:

[0096] (I ac,ct +I dc )|Z ct |≤U n,ocv

[0097] where Z ct is the charge transfer impedance, which is calculated as follows:

[0098]

[0099] U n,ocv is the negative electrode equilibrium potential of the battery at this SOC state. The negative electrode equilibrium potential of the three-electrode battery at different charge states is measured by making a three-electrode battery. ac,ct is the maximum AC heating current amplitude obtained based on the lithium plating model constraints.

[0100] S36: Take I ac,v , I ac,ct and I ac,max The minimum value in the current state is the maximum AC current amplitude allowed by a certain frequency, I ac,max The maximum AC current amplitude that can be applied by the battery.

[0101] S37: Traverse the maximum AC current amplitude allowed at different frequencies (1-1000Hz).

[0102] S4: Calculate the heat generation rate under the maximum AC heating current amplitude of different frequencies based on the frequency domain thermal model; establish a heat generation model based on the frequency domain, such as Figure 4 As shown, the heat generation model calculation formula in the thermal model is:

[0103]

[0104] Among them, Q total is the total heat production, Q dc ​The heat generated by the DC current, that is, the heat generated by the driving current excitation, is calculated by the DC internal resistance. ac The heat generated by AC current, that is, the heat generated by the current used for AC heating, is calculated through AC impedance.

[0105] The heat dissipation model calculation formula in the thermal model is:

[0106] Q c =hA(TT f )

[0107] Where h is the convective heat transfer coefficient, A is the surface area, T f is the ambient temperature. After determining the heat generation model and heat dissipation model of the battery, a thermal model of the battery is established according to the law of conservation of energy to describe the temperature change of the battery itself. The expression is as follows:

[0108]

[0109] Where m is the battery mass and c is the battery specific heat capacity. Figure 5 As shown in (a) and (b), the heat generation rate at the maximum AC heating current amplitude of different frequencies (1-1000Hz) is obtained when the driving excitation current is 0 through the battery frequency domain thermal model and the maximum AC current amplitude allowed at different frequencies.

[0110] S5: Update the optimal current amplitude and frequency in real time until the battery temperature reaches the target temperature. Specifically, based on S4, the AC current amplitude and frequency corresponding to the highest heat generation rate among the frequencies are obtained. This is used as the optimal AC parameter to perform AC heating on the battery and is updated in real time until the battery temperature reaches the target temperature.

[0111] In the embodiment of the present invention, the battery electrothermal coupling model parameters are set and simulation is carried out. Some US06 working conditions are selected as the excitation current of the battery in the driving state, such as Figure 6 As shown in (a)-(d), the battery temperature is heated from -15°C to 0°C within 213s, with an average temperature rise rate of 4.23°C / min. During this process, the frequency and amplitude of the optimal AC heating current are updated and optimized every second. It can be seen that with the increase in battery temperature, the dynamic change of the state of charge and the real-time fluctuation of the driving current excitation, the frequency of the AC heating current generally shows an increasing trend. However, due to the irregular and drastic change characteristics of the driving excitation current itself, the amplitude of the AC heating current also continues to change disorderly. Even so, as Figure 7 As shown in the figure, under the dual stimulation of driving current and AC heating current, the battery never exceeds its upper cut-off voltage of 3.65V and lower cut-off voltage of 2.5V. On the basis of ensuring the safety of the battery, rapid heating is achieved in the driving state.

[0112] Example 2:

[0113] An electronic device comprising a memory and a processor;

[0114] The memory is used to store computer programs;

[0115] The processor is configured to implement the method described in Example 1 when executing the computer program.

[0116] Example 3:

[0117] A computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the method described in Example 1 is implemented.

[0118] Example 4:

[0119] A computer program product includes a computer program, which implements the method described in embodiment 1 when executed by a processor.

[0120] In the above embodiments, references to "this embodiment" in the specification indicate that a particular feature, structure, or characteristic described in conjunction with the embodiment is included in at least some embodiments, but not necessarily all embodiments. Multiple occurrences of "this embodiment" do not necessarily refer to the same embodiment.

[0121] In the above embodiments, although the invention has been described in conjunction with specific embodiments thereof, many alternatives, modifications, and variations of these embodiments will be apparent to those skilled in the art based on the foregoing description. For example, other memory structures (e.g., dynamic RAM (DRAM)) may be used with the embodiments discussed. The embodiments of the present invention are intended to encompass all such alternatives, modifications, and variations that fall within the broad scope of the appended claims.

[0122] Regarding the computer-readable storage medium in this embodiment, those skilled in the art will appreciate that all or part of the steps in the aforementioned method embodiments can be implemented using hardware associated with the computer program. The aforementioned computer program can be stored in a computer-readable storage medium. When executed, the program performs the steps in the aforementioned method embodiments. The aforementioned storage medium includes various media capable of storing program code, such as ROM, RAM, magnetic disks, or optical disks.

[0123] The electronic terminal provided in this embodiment includes a processor, a memory, a transceiver and a communication interface. The memory and the communication interface are connected to the processor and the transceiver and complete communication with each other. The memory is used to store computer programs, the communication interface is used for communication, and the processor and the transceiver are used to run computer programs so that the electronic terminal executes the various steps of the above method.

[0124] In this embodiment, the memory may include a random access memory (RAM), and may also include a non-volatile memory (non-volatile memory), such as at least one disk storage.

[0125] The above-mentioned processor can be a general-purpose processor, including a central processing unit (CPU), a network processor (NP), etc.; it can also be a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, and discrete hardware components.

[0126] The present invention can be used in a wide variety of general-purpose or special-purpose computing system environments or configurations, such as personal computers, server computers, handheld or portable devices, tablet devices, multiprocessor systems, microprocessor-based systems, set-top boxes, programmable consumer electronics, network PCs, minicomputers, mainframe computers, and distributed computing environments that include any of the above.

[0127] The present invention may be described in the general context of computer-executable instructions, such as program modules, executed by a computer. Generally, program modules include routines, programs, objects, components, data structures, and the like that perform specific tasks or implement specific abstract data types. The present invention may also be practiced in distributed computing environments where tasks are performed by remote processing devices connected via a communications network. In a distributed computing environment, program modules may be located in both local and remote computer storage media, including storage devices.

[0128] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solutions, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for AC heating of lithium-ion batteries in a driving state, characterized by: The following steps are involved: S1: Select the battery and obtain relevant battery parameters through HPPC experiment and AC impedance test; S2: Update the equivalent circuit model parameters in real time according to the battery SOC and temperature; S3: Obtain the excitation current under the current driving state, and calculate the maximum AC heating current amplitude of different frequencies under the constraints of the cutoff voltage and lithium plating model based on the model parameters; S4: Calculate the heat generation rate at the maximum AC heating current amplitude at different frequencies based on the frequency domain thermal model; S5: Update the optimal current amplitude and frequency in real time until the battery temperature reaches the target temperature.

2. The method for AC heating of lithium-ion batteries in a driving state according to claim 1, characterized in that: Step S1 specifically includes the following steps: S11: Perform HPPC tests at different SOC states at different temperatures to obtain DC internal resistance data of lithium-ion batteries; S12: Perform EIS tests at different SOC states at different temperatures to obtain AC impedance data of the lithium-ion battery; S13: Obtaining the open circuit voltage of the lithium-ion battery at different SOC states; S14: Obtain the specific heat capacity of the lithium-ion battery and the convection heat transfer coefficient under the current environment.

3. The method for AC heating a lithium-ion battery in a driving state according to claim 1, characterized in that: Step S2 specifically includes the following steps: S21: Obtain the DC internal resistance at different temperatures and SOC states through offline parameter identification of HPPC experimental data; S22: Fitting the battery impedance spectrum obtained from the battery EIS test to obtain the component parameters of the fractional-order model at different temperatures and different SOC states; S23: Obtain the SOC-OCV fitting equation by polynomial fitting method.

4. The AC heating method for lithium-ion batteries in a driving state according to claim 1, characterized in that: Step S3 specifically includes the following steps: S31: Obtain the vehicle's driving speed within the next second and calculate the maximum battery discharge current I within the next second dc,max With the minimum value I dc,min ; S32: Calculate the battery terminal voltage response under driving current excitation based on the Rint model. The calculation formula is: U=U ocv (SOC)-I dc *R dc (SOC,T) Where U is the terminal voltage response of the battery under DC current excitation, U ocv (SOC) is the polynomial response model of the battery open circuit voltage with respect to SOC, I dc is the maximum or minimum value of the driving excitation current within this second, R dc (SOC, T) is the lookup table response of the battery's DC internal resistance with respect to SOC and temperature; S33: Calculate the battery terminal voltage response under AC / DC coupling based on the fractional-order model. The calculation formula is: U total =U+I ac *|Z total | Among them U total is the battery terminal voltage under AC / DC coupling excitation, I ac is the AC current amplitude, Z total is the total battery impedance in the fractional-order model; S34: Calculate the maximum AC heating current amplitude based on the battery upper and lower cutoff voltage constraints: UU min ≤I ac，v |Z total |≤U max -U Among them U min is the battery cut-off voltage, U max is the battery cut-off voltage, I ac，v is the maximum AC heating current amplitude calculated based on the cut-off voltage constraint; S35: Establish a lithium deposition model and calculate the maximum AC heating current amplitude based on the constraints of the lithium deposition model: (I ac , ct +I dc )|Z ct |≤U n,ocv where Z ct is the charge transfer impedance, U n，ocv is the negative electrode equilibrium potential of the battery at this SOC state, I ac，ct is the maximum AC heating current amplitude obtained based on the constraints of the lithium plating model; S36: Take I ac，v , I ac，ct The smaller value is the maximum AC current amplitude allowed for a certain frequency in the current state; S37: Traverse the maximum AC current amplitude allowed at different frequencies.

5. The method for AC heating a lithium-ion battery in a driving state according to claim 1, characterized in that: In step S4, a heat generation model based on the frequency domain is established. The heat generation model calculation formula in the thermal model is: Among them, Q total is the total heat production, Q dc The heat generated by the DC current, that is, the heat generated by the driving current excitation, is calculated by the DC internal resistance. ac The heat generated by AC current, that is, the heat generated by the current used for AC heating, is calculated through AC impedance; The heat dissipation model calculation formula in the thermal model is: Q c =hA(T-T f ) Where h is the convective heat transfer coefficient, A is the surface area, T f is the ambient temperature; According to the law of conservation of energy, a thermal model of the battery is established to describe the temperature change of the battery itself. The expression is as follows: Where m is the mass of the battery, c is the specific heat capacity of the battery; Through the battery frequency domain thermal model and the maximum AC current amplitude allowed at different frequencies, the heat generation rate at the maximum AC heating current amplitude at different frequencies is obtained when the driving excitation current is 0.

6. The AC heating method for lithium-ion batteries in a driving state according to claim 1, characterized in that: In step S5, based on the AC current amplitude and frequency corresponding to the maximum heat generation rate in each frequency obtained in step S4, the battery is AC-heated using the optimal AC parameters and updated in real time until the battery temperature reaches the target temperature.

7. An electronic device, characterized in that: including memory and processor; The memory is used to store computer programs; The processor is configured to implement the lithium-ion battery AC heating method in a driving state as described in any one of claims 1 to 6 when executing the computer program.

8. A computer-readable storage medium, characterized in that The storage medium stores a computer program, and when the computer program is executed by the processor, the method for AC heating a lithium-ion battery in a driving state as described in any one of claims 1 to 6 is implemented.

9. A computer program product, characterized in that: The invention comprises a computer program, which, when executed by a processor, implements the lithium-ion battery AC heating method in a driving state as claimed in any one of claims 1 to 6.

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