Battery impedance acquisition method and device, readable storage medium and computer equipment

Abstract

The invention relates to the field of power batteries and the field of computers, and particularly provides a battery impedance obtaining method and device, a readable storage medium and computer equipment, and the method comprises the steps: obtaining a first voltage of a battery under a first sampling frequency; calculating a second voltage of the battery under a second sampling frequency according to the first voltage, wherein the second sampling frequency is greater than the first sampling frequency; and obtaining the impedance of the battery according to the second voltage. Therefore, the limitation of vehicle-mounted hardware can be broken, and the high-frequency electrochemical impedance of the vehicle-mounted battery can be obtained.

Description

Technical Field

[0001] The present application relates to the fields of power batteries and computers, and specifically provides a method and device for obtaining battery impedance, a readable storage medium, and a computer device. Background Art With the development of science and technology, the application of new energy vehicles is becoming more and more extensive. Power batteries (hereinafter referred to as batteries) are the core technology of new energy vehicles. How to provide batteries with enhanced long life and high safety is also a key problem that the industry needs to solve. Among them, the electrochemical impedance spectroscopy (EIS) of batteries has attracted widespread attention due to its advantages such as non-destructiveness and ability to show electrode process characteristics. However, the electrochemical impedance measured by an electrochemical workstation is time-consuming and expensive, and is not suitable for on-board online use. Therefore, using on-board data to obtain the impedance of the battery online is a current research hotspot. However, the current and voltage data collected by the vehicle battery may not meet the requirements of the online impedance algorithm. Due to hardware limitations, the vehicle current and voltage sampling frequency cannot reach a very high value. According to the sampling theorem, the frequency corresponding to the maximum frequency point of the calculated impedance should be less than or equal to the sampling frequency. If the sampling frequency is too low, the calculated impedance spectrum will not have accurate high-frequency point information. Therefore, there is an urgent need for a method for obtaining power battery impedance that can obtain the electrochemical impedance of a vehicle battery at a higher frequency. Summary of the invention

[0002] The present application aims to solve the above technical problem, namely, how to obtain the electrochemical impedance of a vehicle battery at a higher frequency.

[0003] In a first aspect, the present application provides a method for obtaining battery impedance, the method comprising: obtaining a first voltage of the battery at a first sampling frequency; calculating a second voltage of the battery at a second sampling frequency based on the first voltage, the second sampling frequency being greater than the first sampling frequency; and obtaining the impedance of the battery based on the second voltage.

[0004] Optionally, after obtaining the first voltage of the battery at the first sampling frequency, the method further includes: obtaining a voltage expression based on fitting the first voltage at the first sampling frequency; and calculating the second voltage of the battery at the second sampling frequency based on the first voltage includes: calculating the second voltage of the battery at the second sampling frequency based on the voltage expression.

[0005] Optionally, calculating the second voltage of the battery at the second sampling frequency according to the voltage expression includes: modifying the first sampling frequency in the voltage expression to the second sampling frequency to obtain the second voltage of the battery at the second sampling frequency.

[0006] Optionally, the voltage expression is as follows:

[0007]

[0008] Wherein, E1 is the fitted voltage, a, b, c, d are the parameters obtained based on the first voltage fitting, t is the sampling time matrix, According to the following formula (2):

[0009]

[0010] Wherein, k is the order of summation, and the value of k can be any positive integer.

[0011] Optionally, the second voltage is voltage time domain information, and obtaining the impedance of the battery based on the second voltage includes: performing time-frequency conversion on the second voltage to obtain voltage frequency domain information corresponding to the second voltage; obtaining current frequency domain information of the battery; and obtaining the impedance of the battery based on the voltage frequency domain information and the current frequency domain information.

[0012] Optionally, before performing time-frequency conversion on the second voltage, it also includes: detecting a first mutation point of the second voltage; detecting a second mutation point of the time domain current, the second mutation point being associated with the first mutation point; and aligning the second voltage and the time domain current based on the first mutation point and the second mutation point.

[0013] Optionally, obtaining the current frequency domain information of the battery includes: obtaining the time domain current of the battery; and performing time-frequency conversion on the time domain current to obtain current frequency domain information corresponding to the time domain current.

[0014] Optionally, performing time-frequency conversion on the second voltage to obtain voltage frequency domain information corresponding to the second voltage includes: performing S transformation on the second voltage to obtain voltage frequency domain information corresponding to the second voltage.

[0015] In a second aspect, the present application also provides a device for acquiring battery impedance, the device comprising: a first voltage acquisition module, used to acquire a first voltage of the battery at a first sampling frequency; a second voltage acquisition module, used to calculate a second voltage of the battery at a second sampling frequency based on the first voltage, the second sampling frequency being greater than the first sampling frequency; an impedance acquisition module, used to obtain the impedance of the battery based on the second voltage.

[0016] In a third aspect, the present application further provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the method for obtaining the battery impedance described in any one of the above items is implemented.

[0017] In a fourth aspect, the present application also provides a computer device, comprising: at least one processor; and a memory communicatively connected to the at least one processor; wherein a computer program is stored in the memory, and when the computer program is executed by the at least one processor, the method for obtaining the battery impedance described in any one of the above items is implemented.

[0018] Through the battery impedance acquisition method provided in the present application, it is possible to obtain voltage data (i.e., the first voltage) actually collected at a lower sampling frequency (i.e., the first sampling frequency); and obtain "pseudo high-frequency" data (i.e., the second voltage) at a higher frequency (i.e., the second sampling frequency) based on the low-frequency data, thereby breaking the limitations of the vehicle-mounted hardware and obtaining the electrochemical impedance of the vehicle-mounted battery at a higher frequency.

[0019] Furthermore, the voltage expression of the battery is constructed through mathematical operations to obtain "pseudo high frequency" data from low frequency data. Therefore, the conversion of low frequency data to "pseudo high frequency" data can be realized purely based on mathematical algorithms, which is different from conversion methods such as neural networks or vector machines. Figure 2 The provided solution has a smaller computational level and can be deployed on the vehicle side.

[0020] Furthermore, the mutation point is detected before the time-frequency conversion, and after the second voltage and the time-domain current are aligned, the aligned second voltage and the time-domain current are respectively converted to time-frequency. This is because some redundant data may appear after the alignment, and deleting this redundant data before the time-frequency conversion can effectively reduce the amount of calculation in the time-frequency conversion process.

[0021] Furthermore, the detection of the mutation point and the alignment of the current and voltage can be performed at the first sampling frequency, however, the alignment accuracy is poorer than performing these operations at the second sampling frequency. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The preferred embodiments of the present application are described below in conjunction with the accompanying drawings, in which:

[0023] Figure 1 It is a flowchart of the first method for obtaining battery impedance of the present application;

[0024] Figure 2 is a flow chart of a second method for obtaining battery impedance of the present application;

[0025] Figure 3 yes Figure 1 and Figure 2A flowchart of a specific embodiment of step S103;

[0026] Figure 4 is a schematic diagram of a third method for obtaining battery impedance of the present application;

[0027] Figure 5 It is a schematic diagram of two sudden changes of current I in the present application;

[0028] Figure 6 It is a schematic diagram of a sudden change of voltage U in the present application;

[0029] Figure 7 It is a structural schematic diagram of a battery impedance acquisition device of the present application. DETAILED DESCRIPTION

[0030] The preferred embodiments of the present application are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present application and are not intended to limit the protection scope of the present application.

[0031] It should be noted that in the description of the present application, the terms "upper", "lower", "left", "right", "inner", "outer" and the like indicating directions or positional relationships are based on the directions or positional relationships shown in the drawings, which are only for the convenience of description, and do not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0032] In addition, it should be noted that in the description of this application, unless otherwise clearly specified and limited, the terms "installation", "setting", and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, an indirect connection through an intermediate medium, or the internal connection of two components. For those skilled in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0033] In the description of the present application, the term "A and / or B" represents all possible combinations of A and B, such as just A, just B, or A and B. The term "at least one A or B" or "at least one of A and B" has a similar meaning to "A and / or B" and may include just A, just B, or A and B. The singular terms "one" and "this" may also include plural forms. The "multiple" appearing in the embodiments of the present application refers to two or more. The first, second, etc. descriptions appearing in the embodiments of the present application are only for illustration and distinction of the described objects. There is no order, nor does it represent a special limitation on the number in the embodiments of the present application, and cannot constitute any limitation on the embodiments of the present application.

[0034] As mentioned in the background art, in order to solve the problem of how to obtain the electrochemical impedance of a vehicle-mounted battery with a higher frequency, the present application provides a method and device for obtaining the battery impedance, a readable storage medium, and a computer device.

[0035] It should be noted that in the description of this application, the battery may refer to the power battery pack as a whole; it may also refer to each battery cell in the power battery pack; or multiple battery cells in the power battery pack may be taken as a whole, and the battery represents this whole. The power battery pack provides energy for electrical equipment, and the electrical equipment may refer to electric vehicles, electric aircraft, or other equipment that is powered by a battery pack. The following description takes an electric vehicle (or simply a car, or a vehicle end) as an example, but the technical solution of this application can be migrated to other electrical equipment for implementation.

[0036] First, see Figure 1 , Figure 1 This is a flow chart of a first method for acquiring battery impedance of the present application. The method may specifically include step S101, step S102 and step S103. Each step is described in detail as follows.

[0037] Step S101, obtaining a first voltage of the battery at a first sampling frequency.

[0038] The first sampling frequency is a relatively low sampling frequency, and can be the sampling frequency of the electric vehicle end to the battery. In practical applications, the first sampling frequency is less than or equal to the maximum sampling frequency of the electric vehicle end to the voltage.

[0039] At the first sampling frequency, a plurality of continuous voltages of the battery are obtained and recorded as the first voltage. Optionally, the first voltage can be represented in a matrix or other form.

[0040] Step S102: calculating a second voltage of the battery at a second sampling frequency according to the first voltage, wherein the second sampling frequency is greater than the first sampling frequency.

[0041] The second sampling frequency is higher than the first sampling frequency. Optionally, the second sampling frequency is greater than the maximum sampling frequency of the voltage at the electric vehicle terminal.

[0042] In step S102, a second voltage at a second sampling frequency may be calculated based on the first voltage, and the second voltage may also be represented as a voltage matrix.

[0043] In a specific embodiment of step S102, the first voltage is interpolated to obtain a voltage sampling value with a higher frequency, that is, the second voltage.

[0044] Optionally, the first voltage is interpolated, and a related interpolation logic can be constructed, and the inserted voltage value can be obtained based on the logic. Further, the interpolation logic can be determined based on two adjacent sampled voltage values ​​in the first voltage. For example, the first voltage includes a sampled voltage value a1 of the 1st ms, a sampled voltage value a2 of the 2nd ms, a sampled voltage value a3 of the 3rd ms... Then the second voltage obtained after interpolating the first voltage can be expressed as: voltage value b1 of the 0.5 ms, voltage value a1 of the 1st ms, voltage value b2 of the 1.5 ms, voltage value a2 of the 2nd ms, voltage value b3 of the 2.5 ms, sampled voltage value a3 of the 3rd ms... Wherein, b1, b2, b3... are interpolated values ​​of voltage. The voltage values ​​corresponding to b1, b2, b3... can be determined based on the interpolation logic.

[0045] Step S103: obtaining the impedance of the battery according to the second voltage.

[0046] In a specific embodiment of step S103, the impedance (EIS) of the battery may be obtained based on the second voltage with a higher sampling frequency and the current corresponding to each second voltage value.

[0047] In another specific embodiment of step S103, parameter data of a nonlinear equivalent circuit model of the battery is calculated based on a second voltage with a higher sampling frequency and a current corresponding to each second voltage value, and the impedance of the battery is obtained based on the parameter data.

[0048] Optionally, during the actual use of the battery, its charge and discharge current can be controlled by a battery management system (Battery Management System, referred to as BMS), so that the current remains unchanged or changes controllably in the short term. Thus, the vehicle end can obtain the first current by sampling at the first sampling frequency, and then predict the current of the second sampling frequency (referred to as the second current) based on the change of the current. Among them, the charge and discharge current of the power battery refers to the discharge current when the power battery supplies power to the electric vehicle, or the current when the power battery is charging. The charge and discharge current will change with the working conditions of the electric vehicle (such as acceleration conditions, deceleration conditions, overtaking conditions, parking conditions, uniform speed conditions, cruising conditions, fast charging conditions, slow charging conditions, etc.). Therefore, the sampled current can be interpolated based on the working conditions of the car to obtain the current of the second sampling frequency.

[0049] It should be noted that the vehicle end can also obtain the current at the second sampling frequency in other ways, such as constructing a relevant current expression, and calculating the "pseudo high-frequency" current based on the current expression based on the current sampled at a low frequency. Alternatively, the "pseudo high-frequency" current can be calculated based on the equivalent circuit of the battery.

[0050] Figure 1 In the method for obtaining the battery impedance, the voltage data (i.e., the first voltage) actually collected at a lower sampling frequency (i.e., the first sampling frequency) is used; and "pseudo high-frequency" data (i.e., the second voltage) at a higher frequency (i.e., the second sampling frequency) is obtained by calculation, which can break the limitations of the vehicle-mounted hardware and obtain the electrochemical impedance of the vehicle-mounted battery at a higher frequency.

[0051] In one embodiment, see Figure 2 , Figure 2 A second method for obtaining battery impedance of the present application is provided. Figure 1 After obtaining the first voltage of the battery at the first sampling frequency in step S101, the method may further include: step S201, obtaining a voltage expression based on the first voltage at the first sampling frequency. Step S102, calculating the second voltage of the battery at the second sampling frequency according to the first voltage, may include: step S202, calculating the second voltage of the battery at the second sampling frequency according to the voltage expression.

[0052] That is, the second method for acquiring battery impedance may include step S101, step S201, step S202 and step S103.

[0053] Among them, the voltage expression is an expression in data form, that is, Figure 2A purely mathematical relationship is provided to construct a relationship between the first voltage and the sampling time point. Further, the voltage expression can be converted into a voltage curve.

[0054] Optional, Figure 2 In step S202, calculating the second voltage of the battery at the second sampling frequency according to the voltage expression may include: modifying the first sampling frequency in the voltage expression to the second sampling frequency to obtain the second voltage of the battery at the second sampling frequency.

[0055] That is, the voltage expression includes the variable of sampling frequency, and by modifying the sampling frequency in the voltage expression, the voltage at other sampling frequencies can be obtained. If the sampling frequency is modified to a second frequency with a higher frequency, the second voltage can be obtained.

[0056] In a specific embodiment, the voltage expression in step S201 can be constructed based on the Mittag-Lefler equation. Optionally, the voltage expression is as follows:

[0057]

[0058] Wherein, E1 is the voltage after fitting; a, b, c, d are parameters obtained based on the fitting of the first voltage, and their specific values ​​can be calculated based on multiple points in the first voltage. For different pulse data (voltage data), the obtained parameters are also different, and the voltage equation can be obtained using the parameters. t is the sampling time matrix. For example, if the sampling time interval is set to 1ms, 1000 sampling times are included in 1 second, and the 1000 sampling times can be represented by the sampling time matrix t. After calculating the parameters a, b, c, d in formula (1), the sampling frequency of time is set to high frequency, that is, the sampling time matrix t is changed, and the second voltage at the second sampling frequency can be solved using formula (1).

[0059] In formula (1) It can be obtained according to the following formula (2):

[0060]

[0061] Wherein, k is the order of summation, and the value of k can be any positive integer.

[0062] Figure 2In the method for obtaining the battery impedance, the first voltage is sampled in real time based on the hardware conditions of the vehicle-mounted device, and the battery voltage expression is constructed through mathematical operations based on the first voltage as the data basis. The second voltage at the second sampling frequency is calculated based on the mathematical logic of the voltage expression, and "pseudo high-frequency" data is obtained from the low-frequency data. In this way, the conversion from low-frequency data to "pseudo high-frequency" data can be realized purely based on mathematical algorithms, which is different from conversion methods such as neural networks or vector machines. Figure 2 The provided solution has a smaller computational level and can be deployed on the vehicle side.

[0063] In one embodiment, see Figure 3 , Figure 1 and Figure 2 In step S103, obtaining the impedance of the battery according to the second voltage may include the following steps S1031, S1032 and S1033, which are described in detail as follows.

[0064] Step S1031 , performing time-frequency conversion on the second voltage to obtain voltage frequency domain information corresponding to the second voltage.

[0065] The second voltage is the time domain information of the voltage, and the time domain information of the voltage is converted to the frequency domain by time-frequency conversion to obtain the voltage frequency domain information. Optionally, the time-frequency conversion can be realized by using a time-frequency analysis method such as Fast Fourier Transform (FFT), S-Transform (Stockwell Transform or S-Transform), etc.

[0066] In a specific embodiment, the second voltage is subjected to an S-transform to obtain voltage frequency domain information corresponding to the second voltage. The impedance calculation method of the S-transform is as follows:

[0067] Among them, S(f,τ) is the frequency domain signal after conversion, x(t) is the time domain signal before conversion, f is the frequency, τ is the time constant, and e is the natural constant.

[0068] The windowed Fourier transform is as follows: Formula (4), where h(t-τ) is the Gaussian window function.

[0069] Step S1032, obtaining the current frequency domain information of the battery. The current in step S1032 refers to the current at the second sampling frequency, that is, the second current mentioned above.

[0070] In one embodiment of step S1032, the current frequency domain information of the battery is directly acquired.

[0071] In another embodiment of step S1032, the time domain current of the battery is obtained; the time domain current is time-frequency converted to obtain the current frequency domain information corresponding to the time domain current. Optionally, the time-frequency conversion of the current can be achieved by using time-frequency analysis methods such as Fast Fourier Transform (FFT), S transform (Stockwell Transform or S-Transform), etc. Preferably, the time domain current is S-transformed to obtain the current frequency domain information corresponding to the time domain current. The S-transform can refer to the above formula (3) and formula (4). The adaptive characteristics of the time-frequency analysis such as the Gaussian window (GaussWindow) of the S-transform are very suitable for broadband impedance calculation.

[0072] Step S1033: obtaining the impedance of the battery based on the voltage frequency domain information and the current frequency domain information.

[0073] Optionally, at the second sampling frequency, the frequency domain voltage at each frequency point is divided by the frequency domain current at this frequency point to obtain the electrochemical impedance of the battery at this time. Thus, the electrochemical impedance of the battery at the second sampling frequency is obtained.

[0074] In this embodiment, after the voltage and current of the battery at the second sampling frequency are acquired, time-frequency conversion is performed on them, and both the voltage and current are converted into frequency domain information to calculate the impedance.

[0075] In one embodiment, see Figure 4 , Figure 4 A schematic diagram of the third battery impedance acquisition method of the present application is provided. U(t) is the first voltage, U'(t) is the second voltage, U(t) is calculated by the voltage expression to obtain U'(t); U'(t) is subjected to S transformation to obtain the voltage frequency domain information F U’ (f,τ). I(t) is the first current, I'(t) is the second current, and I'(t) is predicted based on the change of current. S-transform I'(t) is performed to obtain the current frequency domain information F I’ (f,τ). Then the impedance of the battery is Z(f,τ)=F U’ (f,τ) / F I’ (f,τ).

[0076] In one embodiment, see again Figure 3Before step S1031 performs time-frequency conversion on the second voltage, the method may further include: detecting a first mutation point of the second voltage; detecting a second mutation point of the time domain current, wherein the second mutation point is associated with the first mutation point; and aligning the second voltage and the time domain current based on the first mutation point and the second mutation point.

[0077] Since there may be asynchrony when collecting the current and voltage of the actual vehicle, the calculated EIS may have errors. Since the voltage and current mutations are synchronized during the actual use of the battery, the two can be aligned based on the voltage mutation point and the current mutation point.

[0078] Optionally, before, after or simultaneously with the time-frequency conversion of the voltage and / or current, the mutation point of the second voltage (i.e., the first mutation point) and the mutation point of the time domain current (i.e., the second mutation point) can be detected, and the second voltage and the time domain current can be aligned based on the mutation points of the two.

[0079] Preferably, the mutation point is detected before the time-frequency conversion, and after the second voltage and the time-domain current are aligned, the aligned second voltage and the time-domain current are respectively converted to time-frequency. This is because some redundant data may appear after the alignment, and deleting this redundant data before the time-frequency conversion can effectively reduce the amount of calculation in the time-frequency conversion process.

[0080] In another embodiment, please refer again to Figure 4 , U(t) and I(t) can each be identified as a mutation point, and U(t) and I(t) can be aligned based on their mutation points. That is, the detection of the mutation point and the alignment of the current and voltage can be performed at the first sampling frequency. However, compared with the previous embodiment, the alignment accuracy of this embodiment is poor.

[0081] See also Figure 5 and Figure 6 , Figure 5 A schematic diagram of two sudden changes in current I is provided, and the current values ​​corresponding to the sudden change points of the current are I0 and -I0; Figure 6 A schematic diagram of a sudden change in voltage U is provided, where the voltage sudden change point corresponds to time point t0.

[0082] In one embodiment, the detection of the mutation point and the alignment of the voltage and current are performed once every period of time, and the time period at this time is recorded as the detection window. Figure 3In the provided method, an S transform is used to perform time-frequency conversion, and the S transform has a Gaussian window whose width is adaptive to the frequency. Optionally, the detection window can be set according to the Gaussian window so that the detection window can also be adaptive to the frequency. For example, the width of the detection window is equal to the width of the Gaussian window, or the width of the detection window is set to N times the Gaussian window, where N is a positive number. Thus, the present embodiment provides a mutation point detection window that is adaptive to the frequency, and aligns the current and voltage after detecting the mutation points of the current and voltage, effectively processes abnormal data, and solves the asynchronism when collecting the current and voltage of the actual vehicle. The present embodiment also provides a systematic method for processing abnormal data, which can improve the robustness of the method of the present application.

[0001] See also Figure 7 The present application also provides a battery impedance acquisition device 70, which may include: a first voltage acquisition module 701, used to acquire a first voltage of the battery at a first sampling frequency; a second voltage acquisition module 702, used to calculate a second voltage of the battery at a second sampling frequency based on the first voltage, wherein the second sampling frequency is greater than the first sampling frequency; an impedance acquisition module 703, used to obtain the impedance of the battery based on the second voltage.

[0002] In one embodiment, after the first voltage acquisition module 701, the device further includes: a voltage expression module, which is used to obtain a voltage expression based on the first voltage fitting at the first sampling frequency; the second voltage acquisition module 702 can also be used to calculate the second voltage of the battery at the second sampling frequency according to the voltage expression.

[0003] In one embodiment, calculating the second voltage of the battery at the second sampling frequency according to the voltage expression includes: modifying the first sampling frequency in the voltage expression to the second sampling frequency to obtain the second voltage of the battery at the second sampling frequency.

[0004] Optionally, the voltage expression is as follows:

[0005]

[0006] Wherein, E1 is the fitted voltage, a, b, c, d are the parameters obtained based on the first voltage fitting, t is the sampling time matrix, According to the following formula (2):

[0007]

[0008] Wherein, k is the order of summation, and the value of k can be any positive integer.

[0009] In one embodiment, the impedance acquisition module 703 may include: a time-frequency conversion unit, used to perform time-frequency conversion on the second voltage to obtain voltage frequency domain information corresponding to the second voltage; a frequency domain current acquisition unit, used to obtain current frequency domain information of the battery; and an impedance acquisition unit, used to obtain the impedance of the battery based on the voltage frequency domain information and the current frequency domain information.

[0010] In one embodiment, before the time-frequency conversion unit, the battery impedance acquisition device may further include: a first mutation detection module, used to detect a first mutation point of the second voltage; a second mutation detection module, used to detect a second mutation point of the time domain current, the second mutation point is associated with the first mutation point; an alignment module, used to align the second voltage and the time domain current based on the first mutation point and the second mutation point.

[0011] In one embodiment, the frequency domain current acquisition unit may include: a time domain current acquisition subunit, used to acquire the time domain current of the battery; and a time-frequency conversion subunit, used to perform time-frequency conversion on the time domain current to obtain current frequency domain information corresponding to the time domain current.

[0012] In one embodiment, the time-frequency conversion unit may also be used to perform an S transformation on the second voltage to obtain voltage frequency domain information corresponding to the second voltage.

[0013] The details of the battery impedance acquisition device can be found in Figures 1 to 6 The description of the method for obtaining the battery impedance is not repeated here.

[0014] In another embodiment of the present application, a second device for acquiring battery impedance is provided, which includes: a sampling module, used to acquire a first voltage of the battery at a first sampling frequency; a processing module, used to calculate a second voltage of the battery at a second sampling frequency based on the first voltage, wherein the second sampling frequency is greater than the first sampling frequency, and the impedance of the battery is obtained based on the second voltage.

[0015] Optionally, the sampling module is further used to collect the time domain current of the battery; the processing module is further used to perform time-frequency conversion of the current or voltage.

[0016] That is, the sampling module is used to collect information such as the time domain voltage and time domain current of the battery, and the sampling module can be implemented by a circuit board (PCB, FPC, etc.) set on the battery. The processing module is used to perform data processing and calculation work in this application according to the information sampled by the sampling module, and the processing module can be implemented by the following computer equipment.

[0017] According to another embodiment of the present application, a computer device is provided, comprising a memory and a processor, wherein the memory stores a computer program, and when the program is executed by the processor, the steps of the method for obtaining the battery impedance in any of the above embodiments can be implemented. The computer device may refer to a device such as an electric vehicle or an aircraft, or may refer to other controllers such as a BMS or a remote server.

[0018] In a specific embodiment, the computer device of the present application is a controller in a power battery pack, such as a BMS, etc. Since the battery impedance acquisition method provided in the present application requires a small amount of storage and calculation, it can be directly deployed in the battery pack to calculate the electrochemical impedance of a single cell or a whole battery pack in real time.

[0019] Furthermore, after the BMS calculates the EIS of the entire battery pack, it can be transmitted to a remote server or vehicle side for monitoring the safety status of the battery pack.

[0020] The computer device may include a processor, a memory, an input / output interface, a communication interface, a display unit and an input device. The processor, the memory and the input / output interface are connected via a system bus, and the communication interface, the display unit and the input device are connected to the system bus via the input / output interface. The processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The input / output interface of the computer device is used to exchange information between the processor and the external device. The communication interface of the computer device is used to communicate with an external terminal in a wired or wireless manner, and the wireless manner can be implemented through WIFI, a mobile cellular network, NFC (near field communication) or other technologies. When the computer program is executed by the processor, a thermal management control method for a power battery is implemented. The display unit of the computer device is used to form a visually visible picture, which can be a display screen, a projection device or a virtual reality imaging device. The display screen can be a liquid crystal display screen or an electronic ink display screen, and the input device of the computer device can be a touch layer covering the display screen, or a button, trackball or touchpad set on the computer device shell, or an external keyboard, touchpad or mouse.

[0021] According to another embodiment of the present application, a computer-readable storage medium is provided for storing a computer program, wherein the computer program implements the steps of the method for acquiring battery impedance in any of the above-mentioned embodiments when executed by a computer device or a processor.

[0022] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to the memory, database or other medium used in the embodiments provided in the present application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetoresistive random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. As an illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM). The database involved in each embodiment provided in this application may include at least one of a relational database and a non-relational database. Non-relational databases may include distributed databases based on blockchains, etc., but are not limited to this. The processor involved in each embodiment provided in this application may be a general-purpose processor, a central processing unit, a graphics processor, a digital signal processor, a programmable logic device, a data processing logic device based on quantum computing, etc., but are not limited to this.

[0023] Those skilled in the art will appreciate that the various illustrative logical blocks, modules, circuits, and algorithm steps described herein may be implemented as electronic hardware, computer software, or a combination of both.

[0024] In order to show the interchangeability between hardware and software, various schematic components, blocks, modules, circuits and steps are generally described above according to their functionality. Such functionality is implemented in hardware form or software form depending on the specific application and the design restrictions imposed on the overall system. Those skilled in the art can implement the described functionality in a variable manner for specific specific applications, but such implementation decisions should not be understood as causing deviations from the scope of the present application.

[0025] Although only some of the specific embodiments of the present application are described, it should be understood by those skilled in the art that the present application can be implemented in many other forms without departing from its subject matter and scope. Therefore, the examples and embodiments shown are considered to be illustrative rather than restrictive, and the present application may include various modifications and substitutions without departing from the spirit and scope of the present application as defined in the appended claims.

[0026] So far, the technical solutions of the present application have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present application is obviously not limited to these specific embodiments. Without departing from the principles of the present application, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present application.

Claims

1. A method for obtaining battery impedance, characterized in that: The method include:. Acquiring a first voltage of the battery at a first sampling frequency; Calculating a second voltage of the battery at a second sampling frequency according to the first voltage, where the second sampling frequency is greater than the first sampling frequency; The impedance of the battery is obtained according to the second voltage.

2. The method according to claim 1, characterized in that After obtaining the first voltage of the battery at the first sampling frequency, the method further includes: Obtaining a voltage expression based on the first voltage fitting at the first sampling frequency; The calculating a second voltage of the battery at a second sampling frequency according to the first voltage includes: A second voltage of the battery at a second sampling frequency is calculated according to the voltage expression.

3. The method according to claim 2, characterized in that The step of calculating the second voltage of the battery at the second sampling frequency according to the voltage expression includes: The first sampling frequency in the voltage expression is modified to a second sampling frequency to obtain a second voltage of the battery at the second sampling frequency.

4. The method according to claim 2 or 3, characterized in that: The voltage expression is as follows: Wherein, E1 is the fitted voltage, a, b, c, d are the parameters obtained based on the first voltage fitting, t is the sampling time matrix, According to the following formula (2): Wherein, k is the order of summation, and the value of k can be any positive integer.

5. The method according to claim 1, characterized in that The second voltage is voltage time domain information, and obtaining the impedance of the battery according to the second voltage includes: Performing time-frequency conversion on the second voltage to obtain voltage frequency domain information corresponding to the second voltage; Acquiring current frequency domain information of the battery; The impedance of the battery is obtained based on the voltage frequency domain information and the current frequency domain information.

6. The method according to claim 5, characterized in that Before performing time-frequency conversion on the second voltage, the method further includes: Detecting a first mutation point of the second voltage; Detecting a second mutation point of the time-domain current, where the second mutation point is associated with the first mutation point; Based on the first mutation point and the second mutation point, the second voltage and the time-domain current are aligned.

7. The method according to claim 5, characterized in that The obtaining the current frequency domain information of the battery includes: Obtaining the time domain current of the battery; Performing time-frequency conversion on the time-domain current to obtain current frequency-domain information corresponding to the time-domain current.

8. The method according to claim 5, characterized in that The performing time-frequency conversion on the second voltage to obtain voltage frequency domain information corresponding to the second voltage includes: Perform an S transform on the second voltage to obtain voltage frequency domain information corresponding to the second voltage.

9. A device for obtaining battery impedance, characterized in that: The device comprises: A first voltage acquisition module, used to acquire a first voltage of the battery at a first sampling frequency; A second voltage acquisition module, used for calculating a second voltage of the battery at a second sampling frequency according to the first voltage, where the second sampling frequency is greater than the first sampling frequency; An impedance acquisition module is used to obtain the impedance of the battery according to the second voltage.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the method for obtaining battery impedance according to any one of claims 1 to 8 is implemented.

11. A computer device, characterized in that: include: at least one processor; and, a memory communicatively coupled to the at least one processor; Wherein, a computer program is stored in the memory, and when the computer program is executed by the at least one processor, the method for obtaining the battery impedance according to any one of claims 1 to 8 is implemented.

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