Sampling acquisition method and electrochemical impedance measurement method

Abstract

This invention discloses a sampling acquisition method and an electrochemical impedance measurement method, used to acquire a first sampling period number and a first sampling frequency, such that the total number of sampling points equals a preset value for the total number of sampling points, and the sampling period number is a positive integer; specifically, it includes: determining a maximum sampling frequency, a maximum sampling frequency division parameter, and a preset value for the total number of sampling points, wherein the maximum sampling frequency division parameter is a constant and a positive integer, and the preset value for the total number of sampling points is a constant and a positive even number; obtaining a first parameter and a second parameter based on the maximum sampling frequency, the maximum sampling frequency division parameter, and an excitation frequency setting value; obtaining the first sampling period number and the sampling frequency division parameter based on the first parameter, the second parameter, and the preset value for the total number of sampling points; and performing a 2... b The first sampling frequency is obtained by frequency division, where b is the sampling frequency division parameter. This invention can meet the requirements of accurate DFT analysis in a wide frequency band, with simple sampling frequency division, small data processing volume, small resource consumption, and flexible measurement scheme.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of battery, in particular to a sampling acquisition method and an electrochemical impedance measurement method. BACKGROUND

[0002] The rapid development of new energy electric vehicles, the expansion of power grid energy storage demand and other market demands promote the progress of batteries to higher energy density and better fast charging performance. High-density vehicle battery packs and dense energy storage stations composed of multiple independent battery units have higher requirements for battery management systems, including zero tolerance for thermal runaway, life balance, etc. The detection and evaluation of battery health status currently mainly use battery electrochemical impedance spectroscopy (EIS) measurement, which injects current into the battery, collects discrete data, and analyzes the impedance to obtain the impedance, which has the advantages of real-time monitoring, high integration, high safety, low cost, etc.

[0003] The analysis of discrete data uses discrete Fourier transform (DFT), and the frequency spectrum after the transform can theoretically restore the amplitude of each frequency. However, discrete Fourier transform requires coherent sampling, i.e. if the sampling duration does not meet the integer multiple of the signal period, the signal energy will leak and spread to non-real frequencies. At the same time, the frequency resolution after the discrete Fourier transform is inversely proportional to the number of sampling points. To reduce the amount of calculation, fast Fourier transform (FFT) can be used, which is a high-efficiency algorithm for calculating discrete Fourier transform (DFT).

[0004] The prior art usually adopts the method of fixing the number of sampling points in one excitation signal period and adjusting the sampling frequency or signal frequency to make the sampling duration meet the requirement of integer multiple of the signal period, but this method may cause sampling frequency division difficulty or frequency aliasing (resulting in precision reduction); or the method of fixing the sampling frequency and adjusting the excitation frequency to make the sampling duration meet the requirement of integer multiple of the signal period, but in the case of low-frequency excitation sampling, the amount of data to be processed is huge, occupying a large amount of digital resources. Since battery impedance measurement requires high-precision wideband measurement, the existing technical solutions have the disadvantages of sampling frequency division difficulty, large amount of data processing, high resource occupation, and inflexible measurement scheme. SUMMARY

[0005] Therefore, the present application aims to provide a sampling acquisition method and an electrochemical impedance measurement method to solve the problems of the prior art, such as sampling frequency division difficulty, large amount of data processing, high resource occupation, and inflexible measurement scheme.

[0006] The technical solution of the present application is that, on one hand, a sampling acquisition method is provided for electrochemical impedance measurement of a battery, the sampling acquisition method is used to acquire a first sampling period number and a first sampling frequency, so that when an excitation frequency is equal to an excitation frequency setting value, a total sampling point number is equal to a total sampling point preset value, and the sampling period number is a positive integer;

[0007] The first sampling period number and the first sampling frequency respectively represent a sampling period number and a sampling frequency corresponding to the excitation frequency equal to the excitation frequency setting value, and the sampling period number represents a period number of a sampled excitation signal.

[0008] The method for acquiring the first sampling period number and the first sampling frequency specifically includes:

[0009] determining a highest sampling frequency, a maximum sampling frequency division parameter, and the total sampling point preset value, wherein the maximum sampling frequency division parameter is a constant and a positive integer, and the total sampling point preset value is a constant and a positive even number;

[0010] obtaining a first parameter and a second parameter according to the highest sampling frequency, the maximum sampling frequency division parameter, and the excitation frequency setting value;

[0011] obtaining the first sampling period number and a sampling frequency division parameter according to the first parameter, the second parameter, and the total sampling point preset value;

[0012] dividing the highest sampling frequency by 2 b to obtain the first sampling frequency, wherein b is the sampling frequency division parameter.

[0013] Optionally, the sampling frequency division parameter is a non-negative integer less than or equal to the maximum sampling frequency division parameter.

[0014] Optionally, the method for obtaining the first parameter and the second parameter according to the highest sampling frequency, the maximum sampling frequency division parameter, and the excitation frequency setting value specifically includes:

[0015] substituting the excitation frequency setting value into a relationship formula (1) to obtain one or more groups of parameters, each group of parameters including a parameter M and a parameter E, selecting one group of parameters and taking them as the first parameter and the second parameter respectively;

[0016] The relationship formula (1) is f exc =(f smax / 2 D )×M×2 E , wherein f exc represents the excitation frequency, f smax represents the highest sampling frequency, D represents the maximum sampling frequency division parameter, M is a positive number, and E is a non-negative number, (M×2E ) / 2 D ≤1 / 2.

[0017] Optionally, the method of obtaining the first sampling period number and the sampling frequency division parameter according to the first parameter, the second parameter and the total sampling point preset value specifically comprises:

[0018] obtaining the first sampling period number and the sampling frequency division parameter according to the first parameter, the second parameter, the total sampling point preset value and the relationship (2);

[0019] wherein the relationship (2) is N=(C×2 D ) / (M×2 E+b ), wherein N represents the total sampling point number, N is a positive even number, C represents the sampling period number, C is a positive integer, b is a non-negative integer less than or equal to D, 2 D / (M×2 E+b )≥2, and C and M are in a preset linear proportion.

[0020] Optionally, the method of obtaining the first sampling period number and the sampling frequency division parameter according to the first parameter, the second parameter, the total sampling point preset value and the relationship (2) specifically comprises:

[0021] obtaining the first sampling period number according to the first parameter and the preset linear proportion;

[0022] substituting the second parameter and the total sampling point preset value into the relationship (2) to obtain the sampling frequency division parameter.

[0023] Optionally, in the electrochemical impedance measurement of the battery, an excitation signal with an excitation frequency equal to the excitation frequency setting value and a period number greater than or equal to the first sampling period is applied to the battery to be measured, and the battery to be measured is sampled at the first sampling frequency, the period number of the sampled excitation signal is equal to the first sampling period number, and the total sampling point number is equal to the total sampling point preset value.

[0024] Optionally, M in the relationship (1) is a positive integer, and E is a non-negative integer.

[0025] Optionally, C in the relationship (2) is equal to a positive integer multiple of M.

[0026] Optionally, C in the relationship (2) is equal to M.

[0027] Optionally, the total sampling point preset value is equal to a positive integer power of 2.

[0028] Optionally, the excitation frequency setting value is less than or equal to half of the highest sampling frequency.

[0029] Optionally, the excitation frequency setting value is equal to an integer multiple of the product of the highest sampling frequency and an integer power of 2.

[0030] Optionally, the maximum sampling frequency division parameter is determined according to the highest sampling frequency, the lowest sampling frequency and the relationship (3),

[0031] wherein the relationship (3) is f smin =f smax / 2 D wherein f smin represents the lowest sampling frequency, f smax represents the highest sampling frequency, and D represents the maximum sampling frequency division parameter, the highest sampling frequency is less than or equal to the maximum value of the sampling frequency that can be supported by the electrochemical impedance measurement device, and the lowest sampling frequency is greater than or equal to the minimum value of the sampling frequency that can be supported by the electrochemical impedance measurement device.

[0032] Optionally, the method for selecting one set of parameters comprises:

[0033] Setting a frequency threshold, if the excitation frequency setting value is less than the frequency threshold, selecting a set of parameters corresponding to a relatively small M.

[0034] In a second aspect, the present application further provides an electrochemical impedance measurement method for measuring the electrochemical impedance of a battery to be measured, the electrochemical impedance measurement method comprising:

[0035] Obtaining the first sampling period number and the first sampling frequency according to the sampling acquisition method;

[0036] Applying an excitation signal to the battery to be measured, the excitation frequency of the excitation signal being equal to the excitation frequency setting value and the period number being greater than or equal to the first sampling period;

[0037] Sampling the battery to be measured according to the first sampling frequency, the period number of the sampled excitation signal being equal to the first sampling period number, and the total sampling point number being equal to the total sampling point preset value;

[0038] Performing discrete Fourier transform according to the sampling result, and calculating the electrochemical impedance of the battery to be measured at the excitation frequency setting value according to the discrete Fourier transform result.

[0039] Compared with the prior art, the technical scheme of the present application has the following advantages: the sampling acquisition method of the present application can quickly acquire the first sampling period number and the first sampling frequency, so that when the excitation frequency is equal to the excitation frequency setting value, the total sampling point number is equal to the total sampling point preset value, the sampling period number is a positive integer, and the coherent sampling requirement is met to meet the DFT (or FFT) accurate analysis requirement; when electrochemical impedance measurement is performed, the total sampling point number can be equal to the total sampling point preset value in a wide frequency band range, the sampling period number is a positive integer, and the data processing amount and resource occupation are small; the first sampling frequency is equal to the highest sampling frequency divided by 2 raised to a non-negative integer power, the sampling frequency division is simple, and digital hardware implementation is facilitated. Under the condition of meeting the first sampling frequency and the first sampling period constraint, a plurality of selectable sampling strategies can be acquired under the same excitation frequency setting value, which can be selected based on different demand scenarios, has high flexibility, and can realize wide frequency band with high frequency resolution. BRIEF DESCRIPTION OF DRAWINGS

[0040] Figure 1 A flowchart of a method for acquiring a first sampling period number and a first sampling frequency according to an embodiment of the present application is shown. DETAILED DESCRIPTION

[0041] The preferred embodiments of the present application are described in detail below, but the present application is not limited to only these embodiments. The present application covers any alternatives, modifications, equivalent methods and schemes made within the spirit and scope of the present application.

[0042] In order for the public to have a thorough understanding of the present application, specific details are described in detail in the following preferred embodiments of the present application, and the present application can also be completely understood without the description of these details by those skilled in the art.

[0043] To realize high-precision calculation of discrete Fourier transform and full-frequency coverage of electrochemical impedance detection, an embodiment of the present application discloses a sampling acquisition method for electrochemical impedance measurement of a battery, which is used to acquire a first sampling period number and a first sampling frequency, so that when an excitation frequency is equal to an excitation frequency setting value, a total sampling point number is equal to a total sampling point preset value, and a sampling period number is a positive integer.

[0044] Among them, the first sampling period number and the first sampling frequency respectively represent the corresponding sampling period number and the sampling frequency when the excitation frequency is equal to the excitation frequency setting value, and the sampling period number represents the period number of the sampled excitation signal.

[0045] The method for acquiring the first sampling period number and the first sampling frequency of the embodiment of the present application is described with reference to Figure 1 , including the following steps:

[0046] Step S10: determining a highest sampling frequency, a maximum sampling frequency division parameter and a total sampling point preset value, wherein the maximum sampling frequency division parameter is a constant and a positive integer, and the total sampling point preset value is a constant and a positive even number.

[0047] Step S20: obtaining a first parameter and a second parameter according to the highest sampling frequency, the maximum sampling frequency division parameter and an excitation frequency setting value.

[0048] Step S30: obtaining a first sampling period number and a sampling frequency division parameter according to the first parameter, the second parameter and the total sampling point preset value.

[0049] Step S40: obtaining a first sampling frequency by dividing the highest sampling frequency by 2 b , wherein b is the sampling frequency division parameter.

[0050] In some embodiments, the first parameter is a positive integer, and the second parameter is a non-negative integer. Further, in some embodiments, in order to facilitate the implementation of sampling frequency division, the sampling frequency division parameter is limited to a non-negative integer less than or equal to the maximum sampling frequency division parameter.

[0051] In one embodiment, in step S20, the excitation frequency setting value is substituted into the relationship formula (1) to obtain one or more sets of parameters, each set of parameters including a parameter M and a parameter E, and one set of parameters is selected and used as the first parameter and the second parameter, respectively; wherein the relationship formula (1) is f exc =(f smax / 2 D )×M×2 E , wherein f exc represents the excitation frequency, f smax represents the highest sampling frequency, D represents the maximum sampling frequency division parameter, M is a positive number, and E is a non-negative number, and (M×2 E ) / 2 D ≤1 / 2.

[0052] In one embodiment, in step S30, the first sampling period number and the sampling frequency division parameter are obtained according to the first parameter, the second parameter, the total sampling point preset value and the relationship formula (2); wherein the relationship formula (2) is N=(C×2 D ) / (M×2 E+b ), wherein N represents the total sampling point number, N is a positive even number, C represents the sampling period number, C is a positive integer, b is a non-negative integer less than or equal to D, and 2 D / (M×2 E+b)≥2, C and M are in a preset linear proportion. Further, in step S30, the first sampling period number is obtained according to the first parameter and the preset linear proportion; the second parameter and the preset total sampling point number are substituted into the relationship (2) to obtain the sampling frequency division parameter.

[0053] In the present application, the excitation frequency represents the frequency of the excitation signal. It is easily understood that, when performing electrochemical impedance measurement on the battery under test, the excitation signal with the excitation frequency equal to the excitation frequency set value and the period number greater than or equal to the first sampling period is applied to the battery under test, and the battery under test is sampled at the first sampling frequency, and the period number of the sampled excitation signal is equal to the first sampling period number, so that the total sampling point number is equal to the preset total sampling point number, and the sampling period number is a positive integer.

[0054] In a specific implementation, the highest sampling frequency and the maximum sampling frequency division parameter are determined according to the sampling frequency that can be supported by the electrochemical impedance measurement device. Specifically, the highest sampling frequency is less than or equal to the maximum value of the sampling frequency that can be supported by the electrochemical impedance measurement device; and the maximum sampling frequency division parameter is determined according to the highest sampling frequency, the lowest sampling frequency and the following relationship:

[0055] f smin =f smax / 2 D (3)

[0056] wherein f smax represents the highest sampling frequency, f smin represents the lowest sampling frequency, and D represents the maximum sampling frequency division parameter, wherein the lowest sampling frequency is greater than or equal to the minimum value of the sampling frequency that can be supported by the electrochemical impedance measurement device.

[0057] When setting the excitation frequency set value, the excitation frequency set value should meet the requirement of the electrochemical impedance measurement frequency range of the battery under test, and the excitation frequency set value also needs to meet the requirement of being less than or equal to half of the highest sampling frequency f smax to meet the Nyquist sampling theorem.

[0058] The principle and details of the sampling acquisition method of the embodiment of the present application are introduced below.

[0059] To ensure that the number of periods can be intercepted, the following condition needs to be met:

[0060] N = n×C (4)

[0061] wherein N represents the total sampling point number, N is a positive even number, n represents the number of sampling points in one period of the excitation signal, n≥2, C represents the sampling period number, and C is a positive integer.

[0062] The excitation frequency can be expressed as:

[0063] f exc =f smin ×M×2 E (5)

[0064] wherein, f exc represents the excitation frequency, M is a positive number, and E is a non-negative number.

[0065] The relationship formula (1) can be obtained by substituting the relationship formula (3) into the relationship formula (5).

[0066] In order to meet the Nyquist sampling theorem, (M×2 E ) / 2 D ≤1 / 2 in the relationship formula (1).

[0067] The excitation frequency set value is substituted into the relationship formula (1), and a group or more groups of parameters can be obtained by solving, each group of parameters including parameters M and E, and one group of parameters is selected, and M and E in the selected group of parameters are selected as the first parameter and the second parameter respectively.

[0068] In order to simplify the calculation, in some embodiments, M in the relationship formula (1) can be limited to a positive integer, and E can be limited to a non-negative integer. Correspondingly, when setting the excitation frequency set value, it can be set to be equal to an integer multiple of the product of the highest sampling frequency and an integer power of 2.

[0069] In order to facilitate digital design of the sampling frequency, the sampling frequency is set to start from the highest sampling frequency and divide by 2, and the following can be obtained:

[0070] f sample =f smax / 2 b

[0071] wherein, f sample represents the sampling frequency, b represents the sampling frequency parameter, and b is a non-negative integer less than or equal to D, which is the frequency division system.

[0072] Therefore, n can be obtained as:

[0073] n=f sample / f exc

[0074] The above relationship formula is substituted into the relationship formula (4), and the following can be obtained:

[0075] N=n×C=(f sample / f exc )×C=(f smax / 2 b )×(C / (f smax / 2 D ×M×2E ))=(C×2 D ) / (M×2 E+b )

[0076] Thus, the relationship (2) is obtained.

[0077] wherein, since n≥2, 2 D / (M×2 E+b )≥2; since D represents the maximum sampling frequency division parameter, which is a determined constant, when M and E are arbitrarily selected according to the excitation frequency setting value and the relationship (1) (i.e., after the first parameter and the second parameter are determined), it is required to ensure that N is a positive integer, and thus it is required to ensure that C and M are in a preset linear proportion. In some embodiments, in order to simplify the calculation, C in the relationship (2) can be set to be equal to a positive integer multiple of M. In some embodiments, in order to simplify the calculation, the total sampling point preset value can be set to be equal to a positive integer power of 2, and correspondingly, C in the relationship (2) can be set to be equal to an integer power multiple of M. In some embodiments, in order to further simplify the calculation, C in the relationship (2) can be set to be equal to M.

[0078] For example, in one embodiment, C=M is selected, and C=M is substituted into the above relationship (2), which can obtain:

[0079] N=2 D-E-b

[0080] It can be seen that N is an integer equal to an integer power multiple of 2, and after N and E are determined, the sampling frequency division parameter b can be solved, that is, the excitation frequency setting value and the above determined E (the second parameter) are substituted into N=2 D-E-b , and the sampling frequency division parameter b can be solved, and then the highest sampling frequency is divided by 2 b times, and the first sampling frequency can be obtained. Therefore, by using the sampling acquisition method of the embodiments of the present application, according to the determined highest sampling frequency, the maximum sampling frequency division parameter, the total sampling point preset value, and the excitation frequency setting value, the first sampling period number and the first sampling frequency obtained by calculation can be obtained to satisfy that the total sampling point number is equal to the total sampling point preset value, and the sampling period number is a positive integer.

[0081] To realize fast sampling, in one embodiment, a frequency threshold value can be set, if the excitation frequency setting value is less than the frequency threshold value, a corresponding group of parameters with a relatively small M is selected. For example, the frequency threshold value = 1 Hz can be set, if the excitation frequency setting value is less than 1 Hz, in order to realize fast sampling and reduce the sampling time, a group of parameters with M = 1 can be selected, so that when the electrochemical impedance measurement is performed, when the excitation frequency is less than 1 Hz, the sampling cycle number is 1, that is, only one excitation signal cycle is sampled. If the excitation frequency setting value is greater than 1 Hz, different groups of parameters can be selected according to actual conditions, and multiple excitation signal cycles are sampled to reduce the hardware calculation pressure.

[0082] For ease of understanding, a specific example is given below.

[0083] This example still selects C = M, and substituting C = M into the relationship (2) can obtain:

[0084] N = (C x 2 D ) / (M x 2 E+b )= 2 D-E-b

[0085] It can be seen that N can satisfy a positive even integer equal to an integer power of 2.

[0086] The highest sampling frequency is assumed to be 64KHz, since the frequency range of the electrochemical impedance spectrum can be relatively large, to balance the accuracy and data amount, the sampling frequency needs to change with the excitation frequency, so there is a lowest sampling frequency, assuming that the highest sampling frequency is 2 23 times the lowest sampling frequency, that is, D = 23. Then the relationship (1) is:

[0087] f exc =(f smax / 2 D ) x M x 2 E =(f smax / 2 D-E ) x M = (64KHz / 2 23-E ) x M

[0088] It can be seen that the excitation frequency is determined by M and E.

[0089] At the same time, the relationship (2) can be arranged as:

[0090] N = 2 D-E-b = 2 23-E-b

[0091] When setting the total sampling point preset value, the related sampling requirements are considered, for example, the total sampling point preset value is set to 256 here.

[0092] Substitute N=256 and D=23 into the relationship (2), we can get:

[0093] N=256=2 8 =2 23-E-b

[0094] Further, we can get b=15-E.

[0095] Suppose the excitation frequency setting value is 1KHz, we can substitute the excitation frequency setting value into the relationship (1) at this time (it can be understood that we substitute f exc =1kHz into the relationship (1) at this time), and solve to get multiple groups of parameters, each group of parameters including M and E. It is easy to understand that after selecting a group of M and E (that is, after determining the first parameter and the second parameter), the first sampling period number is determined according to C=M. Substitute the selected E value into b=15-E to solve the sampling frequency division parameter b. According to the solved sampling frequency division parameter b, the highest sampling frequency is divided by 2 b to obtain the first sampling frequency. The following table exemplarily shows four groups of parameters and their corresponding C and b:

[0096]

[0097] Each group of M and E represents a sampling strategy, and selecting a group of M and E means selecting a sampling strategy. According to the above table, when a group of parameters M=4 and E=4 is selected, C=4 and b=0 can be obtained, and then the sampling strategy at this time is specifically: the first sampling period number is equal to 4, and the first sampling frequency = f smax / 2 b =64KHz / 2 0 =64KHz; when a group of parameters M=8 and E=14 is selected, C=8 and b=1 can be obtained, and then the sampling strategy at this time is specifically: the first sampling period number is equal to 8, and the first sampling frequency = f smax / 2 b =64KHz / 2 1 =32KHz; the first sampling period number and the first sampling frequency corresponding to the other two groups of M and E can be easily obtained by those skilled in the art according to the foregoing description, and will not be described here. Therefore, the sampling acquisition method of the embodiment of the present application can obtain multiple selectable sampling strategies, and can flexibly select a sampling strategy based on different demand scenarios (such as different DFT (or FFT) accuracy requirements, different sampling time requirements, etc.), so as to realize wide frequency band with high frequency resolution.

[0098] It is easily understood that in the above specific example, the first sampling period number is equal to the selected M because C=M is selected. If in other embodiments, the predetermined linear ratio of C to M in equation (2) is not 1, the first sampling period number needs to be obtained according to the specific predetermined linear ratio and the selected M.

[0099] The embodiment of the present application also provides an electrochemical impedance measurement method for measuring the electrochemical impedance of a battery to be measured, and the electrochemical impedance measurement method comprises the following steps:

[0100] Step 1: obtaining the first sampling period number and the first sampling frequency according to the sampling acquisition method described above;

[0101] Step 2: applying an excitation signal with an excitation frequency equal to the excitation frequency setting value and a period number greater than or equal to the first sampling period to the battery to be measured;

[0102] Step 3: sampling the battery to be measured according to the first sampling frequency, wherein the period number of the sampled excitation signal is equal to the first sampling period number, and the total sampling point number is equal to the total sampling point preset value;

[0103] Step 4: performing discrete Fourier transform according to the sampling result, and calculating the electrochemical impedance of the battery to be measured at the excitation frequency setting value according to the discrete Fourier transform result.

[0104] In specific implementation, the specific method of step 1 can refer to the sampling acquisition method disclosed in the embodiment of the present application, which will not be described here.

[0105] For example, in one embodiment, in step 2, an excitation current signal is applied to the battery to be measured; in step 3, the voltage across the battery to be measured is sampled according to the first sampling frequency to obtain a group of discrete voltage signals; and in step 4, the group of discrete voltage signals is subjected to discrete Fourier transform, and the electrochemical impedance of the battery to be measured at the excitation frequency setting value is calculated according to the discrete Fourier transform result. In one embodiment, in step 4, fast Fourier transform can be used.

[0106] In summary, the sampling acquisition method of the embodiment of the present application prepares for discrete Fourier transform analysis, can quickly acquire the first sampling period number and the first sampling frequency, and makes the total sampling point number equal to the total sampling point preset value when the excitation frequency is equal to the excitation frequency set value, the sampling period number is a positive integer, meets the coherent sampling requirement, and meets the DFT (or FFT) accurate analysis requirement; when electrochemical impedance measurement is performed, the total sampling point number can be equal to the total sampling point preset value in a wide frequency band range, the sampling period number is a positive integer, the data processing amount is small, and the resource occupation is small; the first sampling frequency is equal to the highest sampling frequency divided by a non-negative integer power of 2, the sampling frequency division is simple, and digital hardware implementation is facilitated. Under the condition of meeting the first sampling frequency and the first sampling period constraint, generally, multiple groups of parameters can be obtained under the same excitation frequency set value, different sampling strategies can be obtained by selecting different groups of parameters, and therefore multiple selectable sampling strategies can be acquired, the selection flexibility can be high based on different requirement scenes, and high frequency resolution can be achieved in a wide frequency band.

[0107] The above-described embodiments do not constitute a limitation on the protection scope of the technical solutions. Any modification, equivalent replacement, and improvement made within the spirit and principles of the above-described embodiments shall be included in the protection scope of the technical solutions.

Claims

1. A sampling acquisition method for electrochemical impedance measurement of a battery, characterized in that, the sampling acquisition method is used to acquire a first sampling period number and a first sampling frequency, so that when an excitation frequency is equal to an excitation frequency setting value, a total sampling point number is equal to a total sampling point preset value, and the sampling period number is a positive integer; wherein the first sampling period number and the first sampling frequency represent a corresponding sampling period number and a sampling frequency when the excitation frequency is equal to the excitation frequency setting value, and the sampling period number represents a period number of a sampled excitation signal; the method for acquiring the first sampling period number and the first sampling frequency specifically comprises: determining a highest sampling frequency, a maximum sampling frequency division parameter, and the total sampling point preset value, wherein the maximum sampling frequency division parameter is a constant and a positive integer, and the total sampling point preset value is a constant and a positive even number; obtaining a first parameter and a second parameter according to the highest sampling frequency, the maximum sampling frequency division parameter, and the excitation frequency setting value; obtaining the first sampling period number and a sampling frequency division parameter according to the first parameter, the second parameter, and the total sampling point preset value; dividing the highest sampling frequency by 2 b obtaining the first sampling frequency by dividing the highest sampling frequency by b, wherein b is the sampling division parameter; The method for obtaining the first parameter and the second parameter according to the highest sampling frequency, the maximum sampling frequency division parameter and the excitation frequency setting value specifically comprises substituting the excitation frequency setting value into a relational expression (1) to obtain one or more groups of parameters, each group of parameters comprising a parameter M and a parameter E, selecting one group of parameters and taking the parameters M and E as the first parameter and the second parameter respectively, and the relational expression (1) is f exc =(f smax / 2 D )×M×2 E , wherein f exc represents the excitation frequency, f smax represents the highest sampling frequency, D represents the maximum sampling frequency division parameter, M is a positive number, E is a non-negative number, and (M×2 E ) / 2 D ≤1 / 2. 2.The sampling acquisition method according to claim 1, characterized in that, the sampling frequency division parameter is a non-negative integer less than or equal to the maximum sampling frequency division parameter.

3. The method of claim 1, wherein, the method for obtaining the first sampling period number and the sampling frequency division parameter according to the first parameter, the second parameter, and the total sampling point preset value comprises: obtaining the first sampling period number and the sampling frequency division parameter according to the first parameter, the second parameter, the total sampling point preset value, and a relationship formula (2); The relationship (2) is N=(C×2 D ) / (M×2 E+b ), wherein N represents a total sampling point number, N is a positive even number, C represents a sampling period number, C is a positive integer, b is a non-negative integer less than or equal to D, 2 D / (M×2 E+b )≥2, and C and M are in a preset linear ratio.

4. The method of claim 3, wherein, the method for obtaining the first sampling period number and the sampling frequency division parameter according to the first parameter, the second parameter, the total sampling point preset value, and the relationship formula (2) specifically comprises: obtaining the first sampling period number according to the first parameter and a preset linear ratio; substituting the second parameter and the total sampling point preset value into the relationship formula (2) to obtain the sampling frequency division parameter.

5. The method of claim 1, wherein, In the electrochemical impedance measurement of the battery, an excitation signal with an excitation frequency equal to the excitation frequency setting value and a period number greater than or equal to the first sampling period is applied to the battery to be measured, and the battery to be measured is sampled at the first sampling frequency, the period number of the sampled excitation signal is equal to the first sampling period number, and the total sampling point number is equal to the total sampling point preset value. 6.The sampling acquisition method according to claim 1, characterized in that, M in the relationship formula (1) is a positive integer, and E is a non-negative integer. 7.The sampling acquisition method according to claim 3, characterized in that, C in the relationship formula (2) is equal to a positive integer multiple of M. 8.The sampling acquisition method according to claim 7, characterized in that, C in the relationship formula (2) is equal to M. 9.The sampling acquisition method according to claim 1, characterized in that, the total sampling point preset value is equal to a positive integer power of 2. 10.The sampling acquisition method according to claim 1, characterized in that, The excitation frequency setting value is less than or equal to half of the highest sampling frequency.

11. The sampling acquisition method according to claim 10, wherein, The excitation frequency setting value is equal to an integer multiple of a product of the highest sampling frequency and an integer power of 2.

12. The method of claim 1, wherein, The maximum sampling frequency division parameter is determined according to the highest sampling frequency, the lowest sampling frequency and the relationship (3), wherein the relationship (3) is f smin =f smax / 2 D wherein f smin represents the lowest sampling frequency, f smax represents the highest sampling frequency, and D represents the maximum sampling division parameter, the highest sampling frequency being less than or equal to a maximum value of a sampling frequency that can be supported by the electrochemical impedance measurement device, and the lowest sampling frequency being greater than or equal to a minimum value of a sampling frequency that can be supported by the electrochemical impedance measurement device.

13. The method of claim 1, wherein, The method for selecting one of the groups of parameters comprises: Setting a frequency threshold, if the excitation frequency setting value is less than the frequency threshold, selecting a group of parameters corresponding to a relatively small M.

14. An electrochemical impedance measurement method for measuring electrochemical impedance of a battery under test, characterized by, Comprises: The first sampling period number and the first sampling frequency are obtained according to the sampling acquisition method of any one of claims 1-13; An excitation signal with an excitation frequency equal to the excitation frequency setting value and a period number greater than or equal to the first sampling period is applied to the battery to be tested; The battery to be tested is sampled at the first sampling frequency, the period number of the sampled excitation signal is equal to the first sampling period number, and the total sampling point number is equal to the total sampling point preset value; The electrochemical impedance of the battery to be tested at the excitation frequency setting value is calculated according to the sampling result and the discrete Fourier transform result.

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