Method for detecting ac impedance spectrum of series-connected battery pack by switch array

Abstract

The application provides a method for detecting alternating current impedance spectrum of series battery by switch array, first, key frequency impedance values of the first and last batteries in the battery are determined by detecting alternating current impedance of several specific frequencies, and the first battery is taken as a starting point, switches are controlled to realize mutual and successive series detection of the batteries, and each time frequency change is iterated on the first or last battery according to the existing electrochemical impedance spectrum curve, and impedance spectrum test values of each battery in the series group are sequentially calculated. The application can complete measurement of battery impedance spectrum data without disassembly, reduces measurement time of full sweep, and improves efficiency of online monitoring. The switch array impedance spectrum measurement method can realize online measurement of the battery group, and two-by-two series group measurement can eliminate differential mode interference between single batteries and to ground, so that the measurement value is more accurate, and the alternating current impedance spectrum monitoring can be conveniently completed for large-scale battery groups.

Description

Technical Field

[0001] This application relates to the field of AC impedance spectrum detection technology for battery packs, specifically to a method for calculating the AC impedance spectrum of a series battery pack using a switch array. Background Technology

[0002] In substations, valve-regulated lead-acid batteries are typically configured as battery banks consisting of multiple individual cells connected in series, serving as backup power. During normal substation operation, they operate in a float charge state; however, in the event of a primary system fault, they provide DC drive for relay protection devices, switch opening and closing operations, and secondary-side instruments. This not only ensures timely fault isolation but also provides ample buffer time for maintenance personnel to carry out emergency repairs.

[0003] Since lead-acid batteries in substations serve as DC backup power sources, they cannot undergo frequent capacity testing. Currently, in actual use in substations, the method for estimating the health status of lead-acid batteries is to conduct a capacity test every two years. Moreover, each test requires removing the battery from the substation for individual cell testing, which leads to a longer monitoring cycle for battery internal resistance. This makes it difficult for maintenance personnel to detect batteries that have experienced severe performance degradation during the capacity testing window.

[0004] Traditional substation DC power supply testing methods suffer from long cycles and cannot perform online AC impedance spectroscopy (AC spectroscopy) measurements. Current AC impedance spectroscopy measurement methods involve single-frequency measurements of individual cells using AC injection. After measuring all cells at each frequency, the data is fitted into an AC impedance spectroscopy curve. This requires a switch array to perform AC impedance testing on series-connected lead-acid batteries, reducing the number of individual cell tests, allowing for better understanding of the substation's lead-acid battery health, timely detection of battery failures, and improved reliability of the substation's DC system. However, this method only measures individual cells and cannot adequately measure the entire battery pack, resulting in slow efficiency. Summary of the Invention

[0005] This application addresses the problem that existing measurement methods only measure individual cells of the battery and cannot adequately measure the entire battery pack, resulting in slow efficiency. It provides a method for calculating the AC impedance spectrum of a series battery pack using a switch array detection system. The method includes the following steps:

[0006] Configure the switch array and connect the battery pack;

[0007] Select a first preset number of characteristic frequency points, and perform characteristic frequency impedance tests on the first battery in the first row and the last battery in the last row to obtain the characteristic frequency point measurement values;

[0008] The impedance spectrum variation curves of the first battery cell and the last battery cell in the first row and the last battery cell in the last row are obtained based on the measured values ​​of the characteristic frequency points.

[0009] The impedance spectrum variation curve is fitted and revised with the impedance spectrum standard curve to obtain the error. If the error does not meet the preset error range, it is judged that there is obvious distortion. If the error meets the preset error range, it is judged that there is no obvious distortion.

[0010] If there is obvious distortion, control the switch array to switch the next battery in the first row and the next battery in the last row until there is no obvious distortion in the battery.

[0011] Starting with the battery without obvious distortion, the switch array is controlled to perform parallel measurements and iterative solutions on each row and column of batteries in sequence to obtain the solution data;

[0012] The solution data is stored and analyzed, and impedance spectrum curves are plotted based on the solution data, followed by impedance spectrum analysis.

[0013] In one feasible implementation, the step of sequentially performing parallel measurements and iteratively solving for each row and column of batteries includes:

[0014] The first and last battery packs were measured by selecting a second preset number of characteristic frequency points to obtain the impedance spectrum curves of the first and last battery packs.

[0015] Based on the impedance spectrum curves of the first row of battery packs and the tail row of battery packs, the impedance spectra of the first row of battery packs and the tail row of battery packs are calculated according to a preset step size to obtain the impedance spectrum data of the first row of battery packs and the impedance spectrum data of the tail row of battery packs.

[0016] The first row of battery packs is connected in parallel with the next row of battery packs, and the last row of battery packs is connected in parallel with the previous row of battery packs. The impedance spectrum data of each parallel battery pack is measured by selecting the second preset number of characteristic frequency points.

[0017] Following the previous steps, test each row of battery packs in parallel in pairs, and obtain the impedance spectrum data of the other rows based on the data from the first and last rows.

[0018] The middle two rows of parallel test data are taken for correction to obtain the correction amount;

[0019] The correction amount is used to iteratively correct and solve for the other rows of battery packs.

[0020] In one feasible implementation, the number of the first preset number of characteristic frequency points is 5, namely: 5Hz, 15Hz, 30Hz, 50Hz and 70Hz.

[0021] In one feasible implementation, the number of the second preset number of characteristic frequency points is 10, namely: 1Hz, 5Hz, 10Hz, 15Hz, 30Hz, 40Hz, 50Hz, 60Hz, 70Hz and 75Hz.

[0022] In one feasible implementation, the preset step size is 1Hz.

[0023] In one feasible implementation, the preset error range is: the fitting error with the impedance spectrum standard curve is between 0% and 5%.

[0024] In one feasible implementation, the step of configuring the switch array includes:

[0025] Each battery pack is connected in series to form a column, and every two columns of battery packs are connected in parallel.

[0026] The switch is placed at each parallel node of the two battery packs so that the corresponding batteries in the two battery packs are connected in series to form a switch array.

[0027] In one feasible implementation, the switch array is controlled by a host computer; the steps of the host computer controlling the switch array include:

[0028] The host computer issues control commands, which include: the coordinate position of the switch, and opening / closing information;

[0029] The switch array receives the control command, locates the corresponding switch based on the coordinate position of the switch, and opens or closes the corresponding switch according to the opening / closing information.

[0030] As described above, this application provides a method for calculating the AC impedance spectrum of a series battery pack using a switch array. First, the key frequency impedance values ​​of the first and last cells in the battery pack are determined by detecting the AC impedance at several specific frequencies. Starting with these cells, a switch is controlled to sequentially connect and detect the cells in series. Each frequency change is iteratively calculated for the first or last cell according to an existing electrochemical impedance spectroscopy curve, thus deriving the impedance spectrum test value for each cell in the series group. The beneficial effects are: 1. Battery impedance spectrum data can be measured without disassembly, and the iterative calculation method using characteristic frequencies reduces the measurement time for the entire frequency sweep, providing a faster method for monitoring large battery packs and online battery monitoring, improving the efficiency of online monitoring. 2. The switch array impedance spectroscopy measurement method enables online measurement of battery packs, and the pairwise series grouping measurement effectively eliminates differential-mode interference between individual cells and common-mode interference to ground, making the measurement values ​​more accurate. This method can conveniently perform AC impedance spectroscopy monitoring for large-scale battery packs. Attached Figure Description

[0031] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the implementation of the invention and, together with the description, serve to explain the principles of the embodiments of the invention. It is obvious that the drawings described below are merely some embodiments of the invention, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0032] Figure 1 This is a schematic flowchart illustrating a method for calculating the AC impedance spectrum of a series battery pack using a switch array detection, as shown in an exemplary embodiment of this application.

[0033] Figure 2 This is a schematic flowchart illustrating a method for configuring a switch array, as shown in an exemplary embodiment of this application.

[0034] Figure 3 This is a schematic diagram of an 8×8 switch array with multiple battery packs, as shown in an exemplary embodiment of this application.

[0035] Figure 4 A schematic diagram illustrating the iterative solution process for an exemplary embodiment of this application;

[0036] Figure 5 This is a schematic diagram of a switch array type single battery pack shown as an exemplary embodiment of this application;

[0037] Figure 6 A schematic diagram of an impedance spectrum standard curve shown in an exemplary embodiment of this application;

[0038] Figure 7 This is a schematic diagram illustrating the detection calculation of multiple battery packs in an 8×8 switch array, as shown in an exemplary embodiment of this application. Detailed Implementation

[0039] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that the embodiments of the invention will be more comprehensive and complete, and will fully convey the concept of the exemplary embodiments to those skilled in the art. The described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided to give a full understanding of how embodiments of the invention are carried out.

[0040] In substations, valve-regulated lead-acid batteries are typically configured as battery banks consisting of multiple individual cells connected in series, serving as backup power. During normal substation operation, they operate in a float charge state; however, in the event of a primary system fault, they provide DC drive for relay protection devices, switch opening and closing operations, and secondary-side instruments. This not only ensures timely fault isolation but also provides ample buffer time for maintenance personnel to carry out emergency repairs.

[0041] Based on the operational characteristics of backup power supplies, lead-acid batteries equipped in substations generally have the following features: First, the rated capacity of the batteries is large enough to meet the needs of large-scale energy storage; second, batteries of the same model and batch are used to prevent significant differences in the degree of degradation of individual battery cells due to different current load capacities, which is conducive to the long-term stable operation of the battery pack and also allows for the use of unified standards when testing battery performance; third, they have a long design life to meet the long-term energy storage needs of substations, while reducing the frequency and cost of battery maintenance; fourth, the battery size should be small enough for easy storage and maintenance; fifth, they have good deep discharge tolerance, and their capacity will not drop significantly due to repeated occasional deep discharges; sixth, they are maintenance-free, eliminating the need for maintenance personnel to regularly add electrolyte, thus saving costs; seventh, the plate materials can be recycled after retirement, which meets national environmental protection and sustainable development requirements; and eighth, they are selected from reputable and mature battery products on the market.

[0042] Because lead-acid batteries in substations serve as DC backup power sources, they cannot undergo frequent capacity testing. Currently, in actual substation use, the method for estimating the health status of lead-acid batteries is simply a capacity test every two years. Each test requires removing the battery from the substation for individual cell testing, which lengthens the monitoring cycle for battery internal resistance. This makes it difficult for maintenance personnel to detect batteries that have experienced severe performance degradation during the capacity testing window. Addressing the long testing cycle of traditional substation DC power supplies and the inability to perform online AC impedance spectroscopy measurements, current AC impedance spectroscopy measurements involve single-frequency measurements of individual cells using the AC injection method. After measuring all single-frequency cells, the measured data is fitted into an AC impedance spectroscopy curve. This requires a switch array to achieve AC impedance detection of series-connected lead-acid batteries, reducing the number of individual cell tests, allowing for better understanding of the substation's lead-acid battery health status, timely detection of battery failures, and improved reliability of the substation's DC system.

[0043] This application addresses the problem that existing measurement methods only measure individual cells of the battery pack, resulting in slow efficiency and an inability to adequately measure the entire battery pack. It provides a method for calculating the AC impedance spectrum of a series battery pack using a switch array detection system, referencing... Figure 1 As shown, the method includes the following steps:

[0044] S100: Configures the switch array and connects to the battery pack.

[0045] Specifically, the battery pack can be in one or more columns, as shown in the reference. Figure 2 As shown, in some embodiments, the step of configuring the switch array further includes:

[0046] S110: Each battery pack is connected in series to form a column, and every two columns of battery packs are connected in parallel. It can be understood that when only one column of battery packs is detected, a single row of switches is configured, and all switches are kept closed to connect the battery packs in series.

[0047] S120: The switch is placed at each parallel node of the two battery packs so that the corresponding batteries between the two battery packs are connected in series to form a switch array.

[0048] Reference Figure 3 As shown, Figure 3 Taking a battery pack consisting of 8 batteries in 8 rows as an example, each battery pack is connected in series, and the groups are connected in parallel as shown in the figure. Switches are used at each parallel node to form a large switch array. By controlling the opening and closing of the switches, the series and parallel relationships between the battery packs can be adjusted.

[0049] S200: Select a first preset number of characteristic frequency points, perform characteristic frequency impedance tests on the first battery in the first row and the last battery in the last row, and obtain the characteristic frequency point measurement values.

[0050] S300: Obtain the impedance spectrum variation curves of the first battery cell in the first row and the last battery cell in the last row based on the characteristic frequency measurement values.

[0051] S400: The impedance spectrum variation curve is fitted and revised with the impedance spectrum standard curve to obtain the error. If the error does not meet the preset error range, it is judged that there is obvious distortion. If the error meets the preset error range, it is judged that there is no obvious distortion.

[0052] S500: If there is obvious distortion, control the switch array to switch the next cell in the first row and the next cell in the last row until there is no obvious distortion.

[0053] S600: Starting with a battery without obvious distortion, the control switch array sequentially performs parallel measurements on each row and column of batteries and iteratively solves the problem.

[0054] In some embodiments, refer to Figure 4 As shown, the steps for performing parallel measurements and iterative solutions on each row and column of batteries include:

[0055] S610: Select a second preset number of characteristic frequency points to measure the first and last battery packs to obtain the impedance spectrum curves of the first and last battery packs.

[0056] S620: Based on the impedance spectrum curves of the first and last battery packs, calculate the impedance spectra of the first and last battery packs according to a preset step size to obtain the impedance spectrum data of the first and last battery packs.

[0057] S630: Connect the first row of battery packs in parallel with the next row of battery packs, and connect the last row of battery packs in parallel with the previous row of battery packs. Select a second preset number of characteristic frequency points to measure the impedance spectrum data of each parallel battery pack.

[0058] S640: Following the previous steps, test each row of battery packs in parallel in pairs, and obtain the impedance spectrum data of the other rows based on the data from the first and last rows.

[0059] S650: Take the parallel test data from the middle two rows and correct it to obtain the correction amount.

[0060] S660: Iteratively correct and solve for the other rows of battery packs by adjusting the correction amount.

[0061] S700: Stores and analyzes the solution data, plots impedance spectrum curves based on the solution data, and performs impedance spectrum analysis.

[0062] Specifically, this application illustrates the practical application of a method for calculating the AC impedance spectrum of a series battery pack using a switch array detection system through two embodiments.

[0063] Example 1

[0064] Reference Figure 5 As shown, Figure 5 To test individual battery groups, impedance measurements were first performed on the first battery (cell 1) and the last battery (cell 8) at five representative characteristic frequencies (5Hz, 15Hz, 30Hz, 50Hz, and 70Hz). Electrochemical impedance spectral curves of batteries with the same capacity have been obtained through extensive experiments, resulting in a well-defined standard impedance spectral curve, as shown in the figure below. Figure 6 As shown, according to Figure 6 The standard curve was used to measure the characteristic frequency points of the first and last batteries, and then based on... Figure 6 By fitting and revising the curves shown, the electrochemical impedance spectra of the first and last cells can be obtained, ensuring that the error is within 5%. If the error exceeds 5%, it is considered that there is significant distortion, and the next cell can be selected to perform electrochemical impedance spectroscopy until there is no significant distortion.

[0065] Continue according to Figure 5As shown, seven sets of frequency sweep experiments were performed in sequence. When different frequency signals flowed through the battery in sequence, the switch was turned on and off in sequence according to the signal sent by the host computer to complete the impedance spectrum acquisition of each battery group. At the same time, impedance spectrum analysis was performed. The data of the previous battery in the group was subtracted from the impedance spectrum curve of each battery group. The data of the first battery was iterated each time according to the revised impedance spectrum curve of the first battery. The impedance spectrum data of batteries 2 to 7 were solved in sequence. The last battery group, namely the seventh battery group consisting of the last battery and battery 7, was used for calibration. The revised impedance spectrum curve of the last battery is also known and can be used as calibration to back-derive the impedance spectrum curve of the calibration battery from battery 7 to battery 1.

[0066] The steps for calculating the impedance spectrum of a single battery group are as follows:

[0067] First, the characteristic frequency impedance spectrum data of the first and last two battery cells were measured to complete the correction and fitting of their AC impedance spectrum curves. Then, frequency sweep analysis was performed sequentially starting from the first group, with the measured value for each group of batteries being Z. i +Z i+1 =Z mj (i = 1-7, j = 1-7), based on the impedance spectrum curve of the first battery at its characteristic frequency, the impedance spectrum data of Z2-Z7 can be calculated. The test result of the last group is Z7 + Z8 = Z m7 Now that the revised impedance spectrum curve of the tail section battery Z8 is known, the impedance spectrum data of Z7 can be obtained. This data is then calibrated and revised with the Z7 data obtained in the previous step. By calibrating the impedance spectrum curves of Z7 through Z1 sequentially, a complete AC impedance spectrum can be obtained.

[0068] The impedance spectrum of the entire battery pack can be accurately calculated and calibrated, saving the time required to measure all frequencies of all eight batteries. Since the batteries are connected in series during online measurement, there will be common-mode interference at their common ground. Calibration can effectively eliminate differential-mode and common-mode interference in online measurement, resulting in more accurate and faster results.

[0069] Example 2

[0070] The single-cell testing method described above was applied to multiple cell groups. First, the first and last cells were selected for characteristic frequency measurements to obtain revised electrochemical impedance spectroscopy curves. Then, the switch array was sequentially turned on horizontally and vertically in groups. The first cell iteratively began measurement and calculation towards the center cell, and the last cell also began iterative measurement and calculation towards the center cell. Figure 7 The following is an explanation using an 8×8 battery pack as an example.

[0071] First, complete the switch array configuration, and then the system begins measurements. Figure 7The characteristic frequencies (5Hz, 15Hz, 30Hz, 50Hz, 70Hz) of the batteries are marked with two asterisks. Simultaneously, it is determined whether the measured values ​​of the first and last batteries show significant distortion when compared with the existing standard impedance spectrum curve. If distortion is found, the next battery in the first row and the last row are switched until no batteries show significant distortion. Significant distortion is defined as an error exceeding 5% in the fitting error to the standard impedance spectrum curve.

[0072] Starting with the batteries in the first and last rows that do not exhibit obvious characteristic frequency data distortion, and following the direction shown in the figure, a single-group measurement method is used to quickly measure 10 frequency points (1Hz, 5Hz, 10Hz, 15Hz, 30Hz, 40Hz, 50Hz, 60Hz, 70Hz, 75Hz) of the battery packs in the first and eighth rows.

[0073] Starting from 1 Hz, the impedance spectra of the batteries in the first and eighth rows are calculated using existing curves with a step size of 1 Hz. Then, the battery packs in the first and second rows are connected in parallel, and the battery packs in the eighth and seventh rows are connected in parallel. Both parallel connection methods are tested simultaneously. The swept-frequency impedance spectrum data of each parallel group of the paired parallel battery packs are measured, and Z represents the impedance spectrum of each parallel group. b11 Z b12 Z b13 Z b14 Z b15 Z b16 Z b17 Z b18 Z b81 Z b82 Z b83 Z b84 Z b85 Z b86 Z b87 Z b88 .

[0074] Following this method, test the second and third rows, the seventh and sixth rows, the third and fourth rows, the sixth and fifth rows, and the fourth and fifth rows in sequence. Since the data for the first and last rows are known, the impedance spectrum data Z for the second, third, fourth, fifth, sixth, and seventh rows can be obtained. 2j Z 3j Z 4j Z 5j Z 6j Z 7j (j = 1-8).

[0075] The battery pack data in rows four and five has already been obtained in the previous steps, while the data Z in rows four and five are connected in parallel. b41 Z b42 Z b43 Z b44 Zb45 Z b46 Z b47 Z b48 This is used for iterative correction, and the correction process is shown in the following formula:

[0076] Z 4j / / Z 6j =Z b4j (j = 1-8);

[0077] Calculate Z 4j and Z 5j To correct the known Z error 4j and Z 5j Then came:

[0078] Z ij / / Z i+1j =Z bij (j = 1-7).

[0079] Through Z 4j and Z 5j The correction amount is used to continue iterating and correcting the impedance spectra of other battery groups according to the above formula, while simultaneously completing data storage and analysis, plotting impedance spectrum curves, and performing impedance spectrum analysis.

[0080] In some embodiments of this application, the switch array is controlled by a host computer; the steps of the host computer controlling the switch array include: the host computer issuing a control command, the command including: the coordinate position of the switch and the opening / closing information; the switch array receiving the control command, finding the corresponding switch according to the coordinate position of the switch, and opening or closing the corresponding switch according to the opening / closing information.

[0081] This application utilizes a switch array, controlled by a host computer, for AC impedance spectroscopy testing of battery packs. The switches are controlled by software commands. If a single battery pack is being measured, the switches are switched in series. If multiple battery packs are being measured, iterative calculations are performed starting from the outermost battery, reducing the number of measurements and resulting in more accurate measurements.

[0082] As described above, this application provides a method for calculating the AC impedance spectrum of a series battery pack using a switch array. First, the key frequency impedance values ​​of the first and last cells in the battery pack are determined by detecting the AC impedance at several specific frequencies. Starting with these cells, a switch is controlled to sequentially connect and test the cells in series. Each frequency change is iteratively calculated for the first or last cell according to an existing electrochemical impedance spectroscopy curve, thus deriving the impedance spectrum test value for each cell in the series group. This method allows for the measurement of battery impedance spectrum data without disassembly, reducing the measurement time for full frequency sweeps and improving the efficiency of online monitoring. The switch array impedance spectroscopy measurement method enables online measurement of the battery pack, and the pairwise series grouping measurement effectively eliminates differential-mode interference between individual cells and common-mode interference to ground, resulting in more accurate measurements.

[0083] As can be seen from the foregoing, the embodiments of this application require clarification that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a structure, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a structure, article, or apparatus. Without further limitations, an element defined by the phrase "comprising..." does not exclude the presence of other identical elements in the structure, article, or apparatus that includes that element.

[0084] Other embodiments of this disclosure will readily occur to those skilled in the art upon consideration of the specification and practice of the disclosure herein. This application is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this disclosure are indicated by the following claims.

Claims

1. A method for calculating the AC impedance spectrum of a series battery pack using a switch array detection, characterized in that, The method includes the following steps: Each battery pack in multiple battery groups is connected in series to form a row, and each battery cell in two adjacent rows of battery packs is connected in parallel. The switch is placed at each parallel node position of two adjacent rows of battery packs, so that each corresponding cell in the two adjacent rows of battery packs is connected in series, forming a switch array configuration to connect the battery packs; Select a first preset number of characteristic frequency points, and perform characteristic frequency impedance tests on the first battery in the first row and the last battery in the last row to obtain the characteristic frequency point measurement values; The impedance spectrum variation curves of the first battery cell and the last battery cell in the first row and the last battery cell in the last row are obtained based on the measured values ​​of the characteristic frequency points. The impedance spectrum variation curve is fitted and revised with the impedance spectrum standard curve to obtain the error. If the error does not meet the preset error range, it is judged that there is obvious distortion. If the error meets the preset error range, it is judged that there is no obvious distortion. If there is obvious distortion, control the switch array to switch the next battery in the first row and the next battery in the last row until there is no obvious distortion in the battery. Starting with the battery without obvious distortion, a second preset number of characteristic frequency points are selected to measure the first and last battery packs to obtain the impedance spectrum curves of the first and last battery packs. Based on the impedance spectrum curves of the first row of battery packs and the tail row of battery packs, the impedance spectra of the first row of battery packs and the tail row of battery packs are calculated according to a preset step size to obtain the impedance spectrum data of the first row of battery packs and the impedance spectrum data of the tail row of battery packs. The first row of battery packs is connected in parallel with the next row of battery packs, and the last row of battery packs is connected in parallel with the previous row of battery packs. The impedance spectrum data of each parallel battery pack is measured by selecting the second preset number of characteristic frequency points. Following the previous steps, test each row of battery packs in parallel in pairs, and obtain the impedance spectrum data of the other rows based on the data from the first and last rows. The middle two rows of parallel test data are taken for correction to obtain the correction amount; The solution data is obtained by iteratively correcting and solving the other rows of battery packs using the correction amount. The solution data is stored and analyzed, and impedance spectrum curves are plotted based on the solution data, followed by impedance spectrum analysis.

2. The method for calculating the AC impedance spectrum of a series battery pack using a switch array detection according to claim 1, characterized in that, The first preset number of characteristic frequency points is 5, namely: 5Hz, 15Hz, 30Hz, 50Hz and 70Hz.

3. The method for calculating the AC impedance spectrum of a series battery pack using a switch array detection according to claim 1, characterized in that, The second preset number of characteristic frequency points is 10, namely: 1Hz, 5Hz, 10Hz, 15Hz, 30Hz, 40Hz, 50Hz, 60Hz, 70Hz and 75Hz.

4. The method for calculating the AC impedance spectrum of a series battery pack using a switch array detection according to claim 1, characterized in that, The preset step size is 1Hz.

5. The method for calculating the AC impedance spectrum of a series battery pack using a switch array detection according to claim 1, characterized in that, The preset error range is: the fitting error with the impedance spectrum standard curve is between 0% and 5%.

6. The method for calculating the AC impedance spectrum of a series battery pack using a switch array detection according to claim 1, characterized in that, The switch array is controlled by a host computer; the steps of controlling the switch array by the host computer include: The host computer issues control commands, which include: the coordinate position of the switch, and opening / closing information; The switch array receives the control command, locates the corresponding switch based on the coordinate position of the switch, and opens or closes the corresponding switch according to the opening / closing information.

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