Discontinuous conducting layer equivalent conductivity test system and method based on simulation inversion and medium

Abstract

The invention relates to the technical field of equivalent conductivity testing, and discloses a non-continuous conductive layer equivalent conductivity testing system and method based on simulation inversion and a medium, and the system comprises a testing module which is used for testing a first testing sample corresponding to a magnetic conductive layer of a tested magnetic shielding device to obtain each conductivity, the acquisition module is used for acquiring the initial magnetic conductivity of the second test sample under different magnetic field frequencies and acquiring the actual magnetic field intensity of the tested magnetic shielding device in the magnetic shielding space under different magnetic field frequencies and different excitation magnetic field intensities; the processing module is used for determining intrinsic conductivity, a first relation curve and a second relation curve on the basis of each conductivity acquired from the test module, the initial magnetic conductivity under different magnetic field frequencies and the actual magnetic field intensity in the magnetic shielding space under different magnetic field frequencies and different excitation magnetic field intensities, and performing inversion optimization by using a preset simulation model to obtain a simulation result; and obtaining the target equivalent conductivity of the non-continuous conductive layer of the tested magnetic shielding device.

Description

Technical Field

[0001] This invention relates to the field of equivalent conductivity testing technology, and in particular to a system, method and medium for testing the equivalent conductivity of discontinuous conductive layers based on simulation inversion. Background Technology

[0002] The fundamental principle of magnetic shielding stems from the "magnetic flux shunting" effect of highly permeable materials on static / low-frequency magnetic fields, and the "eddy current shielding" effect of highly conductive materials on high-frequency magnetic fields. To simultaneously suppress the Earth's magnetic field and broadband interference ranging from 0.01 Hz to 1 kHz, passive magnetic shielding devices typically combine a magnetically permeable layer with a highly conductive layer, creating a weak magnetic environment within the shielded space on the order of nT–pT. Clearly, the permeability of the magnetically permeable layer and the conductivity of the highly conductive layer are the core parameters determining the shielding effectiveness.

[0003] In small-scale magnetic shielding boxes / cylinders at the laboratory level, the highly conductive layer is small and thin, and can be formed in one step through processes such as bending and rolling. The conductive path is continuous, and the macroscopic conductivity is approximately equal to the intrinsic value of the material, which can be quickly and accurately measured using the four-probe method. However, when the shielding cavity is scaled up to the meter or even ten-meter level, such as magnetic shielding cavities for magnetoencephalography (MEG) laboratories, zero-magnetic medical chambers, and quantum metrology chambers, the highly conductive layer can only be assembled using a modular method of "small plate-lap-riveting / bolting" due to the constraints of rolling mill width and transportation limits. Factors such as lap gaps, bolt holes, surface oxide films, and uneven contact pressure cause significant contraction and detours in the current path, resulting in a large difference between the equivalent conductivity and intrinsic conductivity of the entire shielding layer, and exhibiting obvious anisotropy.

[0004] Currently, existing technologies only focus on the equivalent conductivity testing of continuous foils or sprayed films. However, there is no corresponding measurement scheme for the equivalent conductivity of discontinuous highly conductive layers in large magnetic shielding devices, which has become a key blind spot restricting the design and simulation accuracy of high shielding performance.

[0005] Therefore, there is an urgent need for a simulation-based inversion system for testing the equivalent conductivity of discontinuous conductive layers to solve the problem that existing technologies cannot quickly and accurately test the equivalent conductivity of discontinuous conductive layers within magnetic shielding devices. Summary of the Invention

[0006] In view of this, the present invention provides a simulation-based inversion equivalent conductivity testing system, method and medium for discontinuous conductive layers, the main purpose of which is to solve the problem that it is currently impossible to quickly and accurately test the equivalent conductivity of discontinuous conductive layers in magnetic shielding devices.

[0007] To address the aforementioned problems, this application provides a simulation-based inversion system for testing the equivalent conductivity of discontinuous conductive layers, comprising: The testing module is used to test the first test sample corresponding to the magnetic permeable layer of the magnetic shielding device under test, obtain the conductivity of the first test sample, obtain the initial magnetic permeability of the second test sample at different magnetic field frequencies, and obtain the actual magnetic field strength in the magnetic shielding space of the magnetic shielding device under test at different magnetic field frequencies and different excitation magnetic field strengths. The processing module, communicatively connected to the testing module, is used to collect various conductivity values, initial permeability at different magnetic field frequencies, and actual magnetic field strength within the magnetic shielding space at different magnetic field frequencies and excitation magnetic field strengths sent by the testing module. Based on the conductivity values, it determines the intrinsic conductivity of the magnetically conductive layer in the passive magnetic shielding device. Based on the initial permeability at different magnetic field frequencies, it determines a first relationship curve between permeability and magnetic field frequency. Based on the actual magnetic field strength within the magnetic shielding space at different magnetic field frequencies and excitation magnetic field strengths, it determines a second relationship curve between the magnetic shielding coefficient and magnetic field frequency. Based on the intrinsic conductivity, the first relationship curve, and the second relationship curve, it performs inversion optimization using a predetermined simulation model to obtain the target equivalent conductivity of the discontinuous conductive layer of the tested magnetic shielding device.

[0008] Optionally, the testing module includes: a four-probe metal tester; The output of the metal four-probe tester is communicatively connected to the input of the processing module; The metal four-probe tester is used to perform several tests on the test sample to obtain several conductivity values, and send each conductivity value to the data processing module. The processing module is used to calculate the intrinsic conductivity of the test sample by performing an average calculation based on each conductivity.

[0009] Optionally, the test module includes: an AC / DC soft magnetic tester; The output terminal of the AC / DC soft magnetic tester is communicatively connected to the input terminal of the processing module; The primary current clamp of the AC / DC soft magnetic tester is electrically connected to the primary winding of the test sample, and the secondary current clamp of the AC / DC soft magnetic tester is electrically connected to the secondary winding of the test sample. The AC / DC soft magnetic tester is used to obtain the initial permeability of the test sample at different frequencies and send the initial permeability at different magnetic field frequencies to the processing module.

[0010] Optionally, the test module includes: a signal generator, a current source, a pair of coils with the same number of turns, and a fluxgate magnetometer; The coil pairs are coaxially and parallelly arranged on both sides of the magnetic shielding device under test; The signal generator has its output terminal electrically connected to the input terminal of the current source, and is used to send sinusoidal current signals of different frequencies to the current source. The current source has its input terminal electrically connected to the output terminal of the signal generator and its output terminal connected to the coil pair. It is used to adjust the received sinusoidal current signal and send the adjusted sinusoidal current signal to each coil in the coil pair so that each coil emits magnetic fields with different magnetic field frequencies and different magnetic field strengths to the magnetic shielding device under test. The fluxgate magnetometer is used to detect the actual magnetic field strength within the magnetic shielding space of the magnetic shielding device under test, and to send the actual magnetic field strength within the magnetic shielding space under different magnetic field frequencies and different excitation magnetic field strengths to the processing module.

[0011] Optionally, the processing module is used to: perform polynomial fitting based on the initial permeability at different magnetic field frequencies to obtain the first relationship curve.

[0012] Optionally, the processing module is used for: The magnetic shielding coefficient is determined based on the excitation magnetic field strength and the actual magnetic field strength at each magnetic field frequency, so as to obtain the magnetic shielding coefficient corresponding to each magnetic field frequency. The second relationship curve is obtained by polynomial fitting based on each magnetic field frequency and the corresponding magnetic shielding coefficient.

[0013] To address the aforementioned problems, this application provides a method for testing the equivalent conductivity of discontinuous conductive layers based on simulation inversion, comprising: The first test sample corresponding to the magnetic conductive layer of the magnetic shielding device under test is tested to obtain the conductivity of the first test sample, and the intrinsic conductivity of the magnetic conductive layer in the passive magnetic shielding device is determined based on the conductivity. The initial permeability of the second test sample under different magnetic field frequencies is obtained, and a first relationship curve between permeability and magnetic field frequency is determined based on the initial permeability under different magnetic field frequencies. The actual magnetic field strength within the magnetic shielding space of the passive magnetic shielding device under different magnetic field frequencies and different excitation magnetic field intensities is obtained, and based on the actual magnetic field strength within the magnetic shielding space under the different magnetic field frequencies and different excitation magnetic field intensities, a second relationship curve between the magnetic shielding coefficient and the magnetic field frequency is determined. Based on the intrinsic conductivity, the first relationship curve, and the second relationship curve, an inversion optimization is performed using a predetermined simulation model to obtain the target equivalent conductivity of the discontinuous conductive layer of the magnetic shielding device under test.

[0014] Optionally, the step of performing inversion optimization using a predetermined simulation model based on the intrinsic conductivity, the first relationship curve, and the second relationship curve to obtain the target equivalent conductivity of the discontinuous conductive layer of the magnetic shielding device under test specifically includes: The intrinsic conductivity is used as the initial equivalent conductivity; The initial equivalent conductivity and the initial permeability corresponding to each magnetic field frequency are input into the simulation model to obtain the simulated magnetic field strength corresponding to each magnetic field frequency; each initial permeability is determined based on the first relationship curve; Based on the simulated magnetic field strength corresponding to each magnetic field frequency and the corresponding actual magnetic field strength, the initial deviation value is calculated using the objective function; each actual magnetic field strength is determined based on the second relationship curve. Based on the initial deviation value and the predetermined deviation threshold, it is determined whether the predetermined optimization stopping condition is met. If the predetermined optimization stopping condition is not met, the initial equivalent conductivity is updated to obtain the current equivalent conductivity. This process continues until the current deviation value calculated based on the current equivalent conductivity meets the predetermined optimization stopping condition. Then, the current equivalent conductivity is taken as the target equivalent conductivity.

[0015] Optionally, determining the intrinsic conductivity of the magnetically conductive layer in the passive magnetic shielding device based on each of the conductivity values ​​specifically includes: calculating the average value based on each of the conductivity values ​​to obtain the intrinsic conductivity of the test sample; The determination of the first relationship curve between magnetic permeability and magnetic field frequency based on the initial magnetic permeability at different magnetic field frequencies specifically includes: The first relationship curve is obtained by polynomial fitting based on the initial permeability at different magnetic field frequencies.

[0016] To address the aforementioned problems, this application provides a storage medium storing a computer program that, when executed by a processor, implements the steps of the simulation-inverted equivalent conductivity testing method for discontinuous conductive layers described above.

[0017] The simulation-inversion-based equivalent conductivity testing system for discontinuous conductive layers in this application utilizes a testing module to acquire the conductivity of the magnetically conductive layer, the initial permeability at different magnetic field frequencies, and the actual magnetic field strength within the magnetically shielded space under different magnetic field frequencies and excitation magnetic field strengths. Subsequently, a processing module can use this measured data to reasonably and accurately determine the intrinsic conductivity, the first relationship curve between permeability and magnetic field frequency, and the second relationship curve between magnetic shielding coefficient and magnetic field frequency. Furthermore, the processing module can use a predetermined simulation model to perform inversion optimization based on the intrinsic conductivity, the first relationship curve, and the second relationship curve to obtain the target equivalent conductivity of the discontinuous conductive layer of the tested magnetic shielding device. This achieves accurate testing of the equivalent conductivity of discontinuous highly conductive layers within large magnetic shielding devices. The equivalent conductivity testing system and method in this application fill a gap in this field, significantly improving the accuracy, convenience, and reliability of the test, and providing core physical property data for the precise design of ultra-large-scale zero-magnetic laboratories and magnetoencephalography / magnetic-cardiac imaging shielding chambers.

[0018] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and in order to make the above and other objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described below. Attached Figure Description

[0019] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings: Figure 1(a) is a schematic diagram of the structure of the magnetic shielding device under test from a first perspective in an embodiment of this application; Figure 1(b) is a schematic diagram of the structure of the magnetic shielding device under test from a first-view perspective in an embodiment of this application; Figure 2 This application provides an embodiment of a simulation-based inversion system for testing the equivalent conductivity of discontinuous conductive layers. Figure 3 This is a flowchart of a method for testing the equivalent conductivity of a discontinuous conductive layer based on simulation inversion, which is another embodiment of this application. Detailed Implementation

[0020] Various embodiments and features of this application are described herein with reference to the accompanying drawings.

[0021] It should be understood that various modifications can be made to the embodiments described herein. Therefore, the above description should not be considered as limiting, but merely as an example of embodiments. Other modifications within the scope and spirit of this application will be apparent to those skilled in the art.

[0022] The accompanying drawings, which are included in and form part of this specification, illustrate embodiments of the present application and, together with the general description of the present application given above and the detailed description of the embodiments given below, serve to explain the principles of the present application.

[0023] These and other features of this application will become apparent from the following description of preferred forms of embodiments given as non-limiting examples, with reference to the accompanying drawings.

[0024] It should also be understood that although this application has been described with reference to some specific examples, those skilled in the art can certainly implement many other equivalent forms of this application.

[0025] The above and other aspects, features and advantages of this application will become more apparent when taken in conjunction with the accompanying drawings and in view of the following detailed description.

[0026] Specific embodiments of this application are described thereafter with reference to the accompanying drawings; however, it should be understood that the claimed embodiments are merely examples of this application, which can be implemented in various ways. Well-known and / or repeated functions and structures are not described in detail to avoid unnecessary or redundant details that could obscure the application. Therefore, the specific structural and functional details claimed herein are not intended to be limiting, but merely serve as the basis and representative basis for the claims to teach those skilled in the art to use this application in a variety of substantially any suitable detailed structures.

[0027] This specification may use the phrases “in one embodiment,” “in another embodiment,” “in yet another embodiment,” or “in other embodiments,” all of which may refer to one or more of the same or different embodiments according to this application.

[0028] This application provides a simulation-based inversion system for testing the equivalent conductivity of discontinuous conductive layers, including: The testing module is used to test the first test sample corresponding to the magnetic permeability layer of the magnetic shielding device under test, obtain the conductivity of the first test sample, obtain the initial permeability of the second test sample at different magnetic field frequencies, and obtain the actual magnetic field strength B in the magnetic shielding space of the magnetic shielding device under test at different magnetic field frequencies and different excitation magnetic field strengths. nf The test sample is ring-shaped. The processing module, communicatively connected to the testing module, is used to collect data sent by the testing module, including various conductivities, initial permeability at different magnetic field frequencies, and actual magnetic field strength B within the magnetically shielded space under different magnetic field frequencies and excitation magnetic field intensities. nfThe intrinsic conductivity of the magnetically conductive layer in the passive magnetic shielding device is determined based on the conductivity of each of the aforementioned conductivity values. A first relationship curve between magnetic permeability and magnetic field frequency is determined based on the initial magnetic permeability at different magnetic field frequencies. A second relationship curve between magnetic shielding coefficient and magnetic field frequency is determined based on the actual magnetic field strength in the magnetic shielding space at different magnetic field frequencies and different excitation magnetic field strengths. Based on the intrinsic conductivity, the first relationship curve, and the second relationship curve, an inversion optimization is performed using a predetermined simulation model to obtain the target equivalent conductivity of the discontinuous conductive layer of the tested magnetic shielding device.

[0029] Specifically, as shown in Figures 1(a) and 1(b), the magnetic shielding device under test in this embodiment can be a passive magnetic shielding device. The structure of this passive magnetic shielding device 1 can be as shown in Figures 1(a) and 1(b), including: a high-permeability magnetic layer / magnetic permeability layer 11 for the magnetic shielding space and a high-conductivity magnetic layer / conductivity layer 12 with a discontinuous structure in the magnetic shielding space. The material of the magnetic permeability layer can be, for example, permalloy, silicon steel, etc.; the material of the high-conductivity layer can be aluminum, copper, or a composite plate thereof, etc. The magnetic permeability layer 11 and the discontinuous high-conductivity layer 12 provide a weak magnetic environment for the large magnetic shielding space.

[0030] In this embodiment, the furnace-bearing sample of the magnetic conductive layer in the magnetic shielding device under test can be used as both the first and second test samples. For example, the first test sample is a circular sample with a diameter of 10 cm, and the sample thickness is determined according to the actual needs of the magnetic conductive layer. Specifically, the second test sample is preferably an annular sample with an outer diameter of 40 mm and an inner diameter of 32 mm, and the sample thickness is determined according to the thickness of the magnetic conductive layer.

[0031] In this embodiment, the overall system structure of the simulation-inverted equivalent conductivity testing system for discontinuous conductive layers is as follows: Figure 2 As shown, it includes a test module 2 and a processing module 3. Specifically, the test module 2 includes: a four-probe metal tester 21, an AC / DC soft magnetic tester 22, a signal generator 24, a current source 25, a pair of coils with the same number of turns 23, and a fluxgate magnetometer 26, etc. The processing module 3 includes computer equipment.

[0032] Specifically, the output of the four-probe metal tester 21 is communicatively connected to the input of the computer / data processing module; the four-probe metal tester 21 is used to perform several tests on the first test sample to obtain several conductivity values, and send each conductivity value to the data processing module / computer / PC; the processing module is used to calculate the average value based on each conductivity value to obtain the intrinsic conductivity of the first test sample.

[0033] In this embodiment, the output terminal of the AC / DC soft magnetic tester 22 is communicatively connected to the input terminal of the processing module / computer / computer 3; the primary current clamp of the AC / DC soft magnetic tester 22 is electrically connected to the primary winding of the second test sample 4, and the secondary current clamp of the AC / DC soft magnetic tester is electrically connected to the secondary winding of the test sample; the AC / DC soft magnetic tester is used to obtain the initial permeability of the test sample at different frequencies, and send the initial permeability at different magnetic field frequencies to the processing module / computer / computer.

[0034] In this embodiment, coil pairs 23 are coaxially and parallelly arranged on both sides of the magnetic shielding device under test; The output terminal of the signal generator 24 is electrically connected to the input terminal of the current source 25, and is used to send sinusoidal current signals of different frequencies to the current source 25. The current source 25 has its input terminal electrically connected to the output terminal of the signal generator 24 and its output terminal connected to the coil pair 23. It is used to adjust the received sinusoidal current signal and send the adjusted sinusoidal current signal to each coil in the coil pair so that each coil emits magnetic fields with different magnetic field frequencies and different magnetic field strengths to the magnetic shielding device under test.

[0035] The fluxgate magnetometer 26 is used to detect the actual magnetic field strength within the magnetic shielding space of the tested magnetic shielding device, and sends the actual magnetic field strength within the magnetic shielding space under different magnetic field frequencies and different excitation magnetic field strengths to the processing module. In this embodiment, the fluxgate magnetometer 26 can be electrically connected to the processing module / power supply 3 via the data acquisition card 27. Specifically, the fluxgate magnetometer 26 / fluxgate sensor can be a 3000Hz Baryington Mag13 type triaxial fluxgate sensor, and the data acquisition card 27 is preferably an NI USB-6366.

[0036] In this embodiment, during the specific implementation process, the processing module / computer 3 is used to: perform polynomial fitting based on the initial permeability at different magnetic field frequencies to obtain the first relationship curve, and to: determine the magnetic shielding coefficient based on the excitation magnetic field strength and the actual magnetic field strength at each magnetic field frequency to obtain the magnetic shielding coefficient corresponding to each magnetic field frequency; and perform polynomial fitting based on each magnetic field frequency and the corresponding magnetic shielding coefficient to obtain the second relationship curve.

[0037] Specifically, the processing module / computer 3 can be equipped with a high-performance workstation. The workstation is pre-installed with corresponding electromagnetic simulation software. Based on the intrinsic conductivity, the first relationship curve, and the first relationship curve, the predetermined electromagnetic simulation software is used to perform inversion optimization / simulation to obtain the target equivalent conductivity of the discontinuous conductive layer of the magnetic shielding device under test.

[0038] The simulation-inversion-based equivalent conductivity testing system for discontinuous conductive layers in this invention tests the conductivity and permeability of the passive magnetic shielding layer as a function of frequency, as well as the magnetic shielding coefficient of a large magnetic shielding space as a function of shielding. Using the measured results as constraints, the system achieves the testing of the equivalent conductivity of discontinuous high-conductivity layers in large magnetic shielding spaces through a test-simulation joint inversion method. This solves the problem of testing the equivalent conductivity of high-conductivity layers in large magnetic shielding spaces based on overlapping processes, and improves the accuracy, convenience, and reliability of the test.

[0039] Another embodiment of this application provides a method for testing the equivalent conductivity of discontinuous conductive layers based on simulation inversion, such as... Figure 3 As shown, it specifically includes: Step S101: Test the first test sample corresponding to the magnetic conductive layer of the magnetic shielding device under test, obtain the conductivity of each of the first test samples, and determine the intrinsic conductivity of the magnetic conductive layer in the passive magnetic shielding device based on each conductivity, wherein the test sample is annular; In the specific implementation process, this step can be based on the average value of each conductivity to obtain the intrinsic conductivity of the test sample.

[0040] Step S102: Obtain the initial permeability of the second test sample at different magnetic field frequencies, and determine the first relationship curve between permeability and magnetic field frequency based on the initial permeability at different magnetic field frequencies. In the specific implementation process, this step can be performed by polynomial fitting based on the initial permeability at different magnetic field frequencies to obtain the first relationship curve.

[0041] Step S103: Obtain the actual magnetic field strength of the passive magnetic shielding device in the magnetic shielding space under different magnetic field frequencies and different excitation magnetic field strengths, and determine the second relationship curve between the magnetic shielding coefficient and the magnetic field frequency based on the actual magnetic field strength in the magnetic shielding space under different magnetic field frequencies and different excitation magnetic field strengths. In the specific implementation process of this step, the magnetic shielding coefficient can be determined based on the excitation magnetic field strength and the actual magnetic field strength at each magnetic field frequency to obtain the magnetic shielding coefficient corresponding to each magnetic field frequency; based on each magnetic field frequency and the corresponding magnetic shielding coefficient, a polynomial fitting is performed to obtain the second relationship curve.

[0042] Step S104: Based on the intrinsic conductivity, the first relationship curve and the second relationship curve, inversion optimization is performed using a predetermined simulation model to obtain the target equivalent conductivity of the discontinuous conductive layer of the magnetic shielding device under test.

[0043] In its specific implementation, this step includes: using the intrinsic conductivity as the initial equivalent conductivity; inputting the initial equivalent conductivity and the initial permeability at each magnetic field frequency into the simulation model to obtain the simulated magnetic field strength corresponding to each magnetic field frequency; each of the initial permeability is determined based on the first relationship curve; calculating the initial deviation value using an objective function based on the simulated magnetic field strength corresponding to each magnetic field frequency and the corresponding actual magnetic field strength; determining whether a predetermined optimization stopping condition is met based on the initial deviation value and a predetermined deviation threshold; if the predetermined optimization stopping condition is not met, updating the initial equivalent conductivity to obtain the current equivalent conductivity, until the current deviation value calculated based on the current equivalent conductivity meets the predetermined optimization stopping condition, and then using the current equivalent conductivity as the target equivalent conductivity.

[0044] In this embodiment, by testing the first relationship curve of the conductivity and permeability of the passive magnetic shielding layer as a function of frequency, and the second relationship curve of the magnetic shielding coefficient of a large magnetic shielding space as a function of shielding, and then using the measured results as constraints, the equivalent conductivity of the discontinuous high conductivity layer in a large magnetic shielding space is tested through a test-simulation joint inversion method. This solves the problem of testing the equivalent conductivity of the high conductivity layer in a large magnetic shielding space based on the overlapping process, and improves the accuracy, convenience and reliability of the test.

[0045] As a specific implementation of the above embodiments, another embodiment of this application provides a method for testing the equivalent conductivity of discontinuous conductive layers based on simulation inversion, the method comprising: Step 1: Use a four-probe metal detector to test the conductivity of the magnetic layer; In this embodiment, before testing, the metal four-probe tester needs to be connected to the data acquisition device computer / data processing module, and the communication interface protocol needs to be adjusted to complete the communication connection. The 10cm diameter magnetic conductive layer sample was placed on the test platform with the center point as the reference point. The conductivity of the sample and the required excitation current were initially determined by using automatic measurement with manual adjustment. After adjustment, select the center point of the front and back of the test sample / first test sample, as well as the top, bottom, left and right points as test points, for a total of 10 test points; After the test was completed, the average conductivity values ​​of the 10 test points were taken and defined as the intrinsic conductivity σ of the magnetic layer.

[0046] Step 2: Next, we need to test the relationship between the permeability of the magnetic layer and the frequency to obtain the first relationship curve between the permeability and the magnetic field frequency. In this step, before testing, it is necessary to determine the number of primary and secondary winding turns of the test sample ring / test sample according to the national standard GB / T3657-83 Test Method for DC Magnetic Properties of Soft Magnetic Alloys. The specific number of winding turns needs to be determined according to the material properties, and this embodiment does not make a specific limitation. The primary and secondary coils are wound on the magnetic layer of the furnace sample ring / second test sample. During the winding process, attention should be paid to the insulation treatment between the wires and between the wires and the test sample ring. In the specific implementation process, the simulated impact method can be used, and the test frequency can be set in the range of 0.01Hz-1000Hz. The preferred test frequencies are 0.01, 0.1, 0.5, 1, 5, 10, 20, 51, 100, 200, 500, 800, and 1000Hz. Among them, 51Hz is to avoid interference from 50Hz power frequency signals in the environment.

[0047] Connect the primary and secondary windings of the test ring to the primary and secondary current clamps of the AC soft magnetic tester, respectively. Start the AC / DC soft magnetic tester, first demagnetize the test ring / test sample, then set the test frequency to 0.01Hz, and obtain the BH curve of the test ring / test sample. Then, obtain the initial permeability μ of the test ring at the 0.01Hz frequency using this BH curve. 0.01 .

[0048] After demagnetizing the sample ring again, the test frequency was adjusted to 0.1 Hz, and the BH curve of the sample ring was tested again. The initial permeability μ of the sample ring at the corresponding frequency was obtained. 0.1 .

[0049] Repeat the above demagnetization and frequency setting test steps to obtain the BH curve of the sample ring at the set frequency, and the correlation between the corresponding magnetic field frequency and the initial permeability, so as to obtain the relationship between frequency f and permeability μ. f The first relationship curve between the two points. To determine the first relationship curve, Origin software can be used to perform polynomial fitting on a finite number of test points.

[0050] Step 3: Test the second relationship curve between the magnetic shielding coefficient of the magnetic shielding device under test and the magnetic field frequency (i.e., the relationship curve between the magnetic shielding coefficient of the magnetic shielding space and the frequency). In this step, before testing the second relationship curve, the signal generator, high-precision current source, data acquisition board, and computer can be connected. Simultaneously, a pair of large coils with equal number of turns are coaxially and parallelly arranged on both sides of the passive magnetic shielding assembly, and the coils are connected to the high-precision current source.

[0051] Next, it is necessary to determine the relationship between the input current of the current source and the magnitude of the excitation magnetic field generated by the coil. At the frequency to be measured, a fixed current value I is set, and the magnitude of the background magnetic field B at the center point of the coil axis is measured. 0f The background magnetic field B here 0f The size is determined by the actual testing requirements, and the current value is determined by B. 0f The ampere-turns of the coil are determined by the coil itself, and no specific limitation is made in this embodiment.

[0052] The fluxgate magnetometer, data acquisition board, computer / data processing module (data recording device), high-precision current source, and signal generator are turned on in sequence. A sinusoidal current signal of a specific frequency is input to the high-precision current source through the signal generator. The magnitude of the sinusoidal current signal output to the coil is adjusted by the current source so that the coil emits a magnetic field of a specific frequency and intensity to the passive magnetic shielding component.

[0053] The excitation magnetic field generated by the coil is shielded by the passive magnetic shielding component, forming a weak magnetic environment inside the magnetic shielding space. The strength of the weak magnetic field inside the magnetic shielding space is tested by a fluxgate magnetometer and recorded by a data recording device.

[0054] In this embodiment, after the excitation magnetic field emitted by the coil is shielded by the passive magnetic shielding component, a weak magnetic space is formed inside the magnetic shielding space. Then, the magnetic field strength at the center point of the magnetic shielding space at the frequency f is measured by a fluxgate magnetometer, the data is collected by a data acquisition board, and finally the measured magnetic field strength is recorded by a data recording device.

[0055] By adjusting the frequency f using a signal generator, the above test and recording methods were repeated to record the magnetic field strength B inside the magnetically shielded space at different frequencies. nf .

[0056] It should be noted that the parameter "shielding coefficient S" is used in this embodiment. f The value is used to measure the ability of a large magnetic shielding space to shield high-frequency magnetic fields. The higher the value, the better the shielding performance. The corresponding calculation formula is shown below: S f =

[0057] Among them, B 0f B represents the excitation magnetic field strength of the coil emission, i.e., the background magnetic field strength of the large magnetically shielded space; nf This represents the actual magnetic field strength inside a large magnetically shielded space.

[0058] Based on the above shielding coefficient S f The calculation formula for B. 0f / B nfThis allows us to obtain the large-scale magnetic shielding spatial magnetic shielding coefficient S. f The correlation curve between the frequency f and the frequency f is obtained as the second correlation curve. In this step, Origin software can also be used to perform polynomial fitting on a limited number of test points to obtain the second correlation curve.

[0059] Step 4: Simulation optimization; In this step, an appropriate optimization algorithm can be selected based on the objective function to simulate and calculate the equivalent conductivity of the discontinuous highly conductive layer.

[0060] In this embodiment, a simulation model can be constructed in the software at a 1:1 scale according to the actual working conditions; The first relationship curve f-μ between the intrinsic conductivity σ, frequency, and initial permeability of the magnetic permeable layer obtained by the aforementioned data processing module. f And the magnetic shielding space magnetic shielding coefficient S f The second relationship curve between frequency f and the target equivalent conductivity is used as a fixed input condition. The equivalent conductivity σ_equiv of the high-conductivity layer / conducting layer is used as the variable to be inverted for parameter inversion / optimization. This process continues until the target equivalent conductivity is obtained. The specific optimization / inversion process is as follows: the intrinsic conductivity is used as the initial equivalent conductivity; the initial equivalent conductivity and the initial permeability at each magnetic field frequency are input into the simulation model to obtain the simulated magnetic field strength corresponding to each magnetic field frequency; each initial permeability is determined based on the first relationship curve; based on the simulated magnetic field strength corresponding to each magnetic field frequency and the corresponding actual magnetic field strength, an initial deviation value is calculated using the objective function; based on the initial deviation value and a predetermined deviation threshold, it is determined whether a predetermined optimization stopping condition is met. If the predetermined optimization stopping condition is not met, the initial equivalent conductivity is updated to obtain the current equivalent conductivity, until the current deviation value calculated based on the current equivalent conductivity meets the predetermined optimization stopping condition, at which point the current equivalent conductivity is used as the target equivalent conductivity.

[0061] In this step, the objective function can be iteratively solved using a least-squares optimization algorithm until Δ is less than a preset deviation threshold. The final σ_equiv is then output as the equivalent conductivity of the discontinuous conductive layer. Specifically, the objective function is as follows: Δ=Σ_f‖B_sim(μ, σ_equiv) B_in(f)‖² Where B_sim(μ, σ_equiv) represents the simulated magnetic field strength; B_in(f) is the actual magnetic field strength; and Δ represents the current deviation value.

[0062] In this embodiment, the optimization algorithm can be any one of Levenberg-Marquardt, genetic algorithm, particle swarm optimization, or Bayesian inversion. The choice of algorithm needs to be considered comprehensively based on the simulation purpose and simulation efficiency. No specific limitation is made in this embodiment of the invention.

[0063] In this embodiment, during the optimization simulation process, the discontinuous regions of the conductive layer can be equivalently homogenized in each iteration. The equivalent layer thickness t_eq=Σ_i t_i and the equivalent fill factor η=Σ_i A_i / A_total are used to jointly describe the process, ensuring the engineering interpretability of the inversion parameters. That is, the fill factor can be determined based on the size, thickness, and other scale information of the discontinuous regions of the conductive layer, and then this fill factor η is added to the simulation model to make the equivalent conductivity output by the simulation model more reasonable in each iteration.

[0064] In this embodiment, by substituting the inverted σ_equiv into the simulation model, the shielding effectiveness of the passive magnetic shielding component at other frequency points in the 0.01Hz-1kHz frequency band is predicted, and cross-validated with the measured results. If the relative error is greater than 5%, the simulation is returned to be re-optimized until the accuracy requirements are met.

[0065] The method in this application, through actual testing of the relationship between the conductivity and permeability of the passive magnetic shielding layer and frequency, and the relationship between the magnetic shielding coefficient of the magnetic shielding space and shielding, uses the test results as input conditions for the electromagnetic simulation model, and jointly inverts to obtain the equivalent conductivity of the discontinuous conductive layer in a large magnetic shielding space. This method realizes the testing of the equivalent conductivity of the disconnected conductive layer in a large magnetic shielding space, solves the problem of imperfect testing methods for the equivalent conductivity of discontinuous conductive layers, and improves the accuracy, convenience and reliability of the test.

[0066] Another embodiment of this application provides a storage medium storing a computer program, which, when executed by a processor, implements the following method steps: Step 1: Test the first test sample corresponding to the magnetic conductive layer of the magnetic shielding device under test, obtain the conductivity of each of the first test samples, and determine the intrinsic conductivity of the magnetic conductive layer in the passive magnetic shielding device based on each conductivity. Step 2: Obtain the initial permeability of the second test sample at different magnetic field frequencies, and determine the first relationship curve between permeability and magnetic field frequency based on the initial permeability at different magnetic field frequencies; Step 3: Obtain the actual magnetic field strength within the magnetic shielding space of the passive magnetic shielding device under different magnetic field frequencies and different excitation magnetic field intensities, and determine the second relationship curve between the magnetic shielding coefficient and the magnetic field frequency based on the actual magnetic field strength within the magnetic shielding space under different magnetic field frequencies and different excitation magnetic field intensities. Step 4: Based on the intrinsic conductivity, the first relationship curve, and the second relationship curve, perform inversion optimization using a predetermined simulation model to obtain the target equivalent conductivity of the discontinuous conductive layer of the magnetic shielding device under test.

[0067] The specific implementation process of the above method steps can be found in any of the above embodiments of the simulation-based inversion method for testing the equivalent conductivity of discontinuous conductive layers. This embodiment will not be repeated here.

[0068] The storage medium in this application, through actual testing of the relationship between the conductivity and permeability of the passive magnetic shielding layer and frequency, and the relationship between the magnetic shielding coefficient of the magnetic shielding space and shielding, uses the test results as input conditions for the electromagnetic simulation model, and jointly inverts to obtain the equivalent conductivity of the discontinuous conductive layer in a large magnetic shielding space. This realizes the testing of the equivalent conductivity of the disconnected conductive layer in a large magnetic shielding space, solves the problem of imperfect testing methods for the equivalent conductivity of discontinuous conductive layers, and improves the accuracy, convenience and reliability of the test.

[0069] The above embodiments are merely exemplary embodiments of this application and are not intended to limit this application. The scope of protection of this application is defined by the claims. Those skilled in the art can make various modifications or equivalent substitutions to this application within its substance and scope of protection, and such modifications or equivalent substitutions should also be considered to fall within the scope of protection of this application.

Claims

1. A simulation-based inversion system for testing the equivalent conductivity of discontinuous conductive layers, characterized in that, include: The testing module is used to test the first test sample corresponding to the magnetic permeable layer of the magnetic shielding device under test, obtain the conductivity of the first test sample, obtain the initial magnetic permeability of the second test sample at different magnetic field frequencies, and obtain the actual magnetic field strength in the magnetic shielding space of the magnetic shielding device under test at different magnetic field frequencies and different excitation magnetic field strengths. The processing module, communicatively connected to the testing module, is used to collect various conductivity values ​​of the testing module, initial permeability at different magnetic field frequencies, and actual magnetic field strength within the magnetic shielding space at different magnetic field frequencies and different excitation magnetic field strengths. Based on the conductivity values, it determines the intrinsic conductivity of the magnetically conductive layer in the passive magnetic shielding device. Based on the initial permeability at different magnetic field frequencies, it determines a first relationship curve between permeability and magnetic field frequency. Based on the actual magnetic field strength within the magnetic shielding space at different magnetic field frequencies and different excitation magnetic field strengths, it determines a second relationship curve between the magnetic shielding coefficient and magnetic field frequency. Based on the intrinsic conductivity, the first relationship curve, and the second relationship curve, it performs inversion optimization using a predetermined simulation model to obtain the target equivalent conductivity of the discontinuous conductive layer of the tested magnetic shielding device.

2. The system as described in claim 1, characterized in that, The testing module includes: a four-probe metal tester; The output of the metal four-probe tester is communicatively connected to the input of the processing module; The metal four-probe tester is used to perform several tests on the test sample to obtain several electrical conductivities, and send each of the electrical conductivities to the processing module. The processing module is used to calculate the intrinsic conductivity of the test sample by performing an average calculation based on each conductivity.

3. The system as described in claim 1, characterized in that, The testing module includes: an AC / DC soft magnetic tester; The output terminal of the AC / DC soft magnetic tester is communicatively connected to the input terminal of the processing module; The primary current clamp of the AC / DC soft magnetic tester is electrically connected to the primary winding of the test sample, and the secondary current clamp of the AC / DC soft magnetic tester is electrically connected to the secondary winding of the test sample. The AC / DC soft magnetic tester is used to obtain the initial permeability of the test sample at different frequencies and send the initial permeability at different magnetic field frequencies to the processing module.

4. The system as described in claim 1, characterized in that, The test module includes: a signal generator, a current source, a pair of coils with the same number of turns, and a fluxgate magnetometer; The coil pairs are coaxially and parallelly arranged on both sides of the magnetic shielding device under test; The signal generator has its output terminal electrically connected to the input terminal of the current source, and is used to send sinusoidal current signals of different frequencies to the current source. The current source has its input terminal electrically connected to the output terminal of the signal generator and its output terminal connected to the coil pair. It is used to adjust the received sinusoidal current signal and send the adjusted sinusoidal current signal to each coil in the coil pair so that each coil emits magnetic fields with different magnetic field frequencies and different magnetic field strengths to the magnetic shielding device under test. The fluxgate magnetometer is used to detect the actual magnetic field strength within the magnetic shielding space of the magnetic shielding device under test, and to send the actual magnetic field strength within the magnetic shielding space under different magnetic field frequencies and different excitation magnetic field strengths to the processing module.

5. The system as described in claim 3, characterized in that, The processing module is used to: perform polynomial fitting based on the initial permeability at different magnetic field frequencies to obtain the first relationship curve.

6. The system as described in claim 4, characterized in that, The processing module is used for: The magnetic shielding coefficient is determined based on the excitation magnetic field strength and the actual magnetic field strength at each magnetic field frequency, so as to obtain the magnetic shielding coefficient corresponding to each magnetic field frequency. The second relationship curve is obtained by polynomial fitting based on each magnetic field frequency and the corresponding magnetic shielding coefficient.

7. A method for testing the equivalent conductivity of a discontinuous conductive layer based on simulation inversion, characterized in that, include: The first test sample corresponding to the magnetic conductive layer of the magnetic shielding device under test is tested to obtain the conductivity of the first test sample, and the intrinsic conductivity of the magnetic conductive layer in the passive magnetic shielding device is determined based on the conductivity. The initial permeability of the second test sample under different magnetic field frequencies is obtained, and a first relationship curve between permeability and magnetic field frequency is determined based on the initial permeability under different magnetic field frequencies. The actual magnetic field strength within the magnetic shielding space of the passive magnetic shielding device under different magnetic field frequencies and different excitation magnetic field intensities is obtained, and based on the actual magnetic field strength within the magnetic shielding space under the different magnetic field frequencies and different excitation magnetic field intensities, a second relationship curve between the magnetic shielding coefficient and the magnetic field frequency is determined. Based on the intrinsic conductivity, the first relationship curve, and the second relationship curve, an inversion optimization is performed using a predetermined simulation model to obtain the target equivalent conductivity of the discontinuous conductive layer of the magnetic shielding device under test.

8. The method as described in claim 7, characterized in that, The step of obtaining the target equivalent conductivity of the discontinuous conductive layer of the tested magnetic shielding device by inversion optimization using a predetermined simulation model based on the intrinsic conductivity, the first relationship curve, and the second relationship curve specifically includes: The intrinsic conductivity is used as the initial equivalent conductivity; The initial equivalent conductivity and the initial permeability corresponding to each magnetic field frequency are input into the simulation model to obtain the simulated magnetic field strength corresponding to each magnetic field frequency; each initial permeability is determined based on the first relationship curve; Based on the simulated magnetic field strength corresponding to each magnetic field frequency and the corresponding actual magnetic field strength, the initial deviation value is calculated using the objective function; each actual magnetic field strength is determined based on the second relationship curve. Based on the initial deviation value and the predetermined deviation threshold, it is determined whether the predetermined optimization stopping condition is met. If the predetermined optimization stopping condition is not met, the initial equivalent conductivity is updated to obtain the current equivalent conductivity. This process continues until the current deviation value calculated based on the current equivalent conductivity meets the predetermined optimization stopping condition. Then, the current equivalent conductivity is taken as the target equivalent conductivity.

9. The method as described in claim 7, characterized in that, The determination of the intrinsic conductivity of the magnetically conductive layer in the passive magnetic shielding device based on each of the aforementioned conductivityes specifically includes: calculating the average value based on each of the aforementioned conductivityes to obtain the intrinsic conductivity of the test sample; The determination of the first relationship curve between magnetic permeability and magnetic field frequency based on the initial magnetic permeability at different magnetic field frequencies specifically includes: The first relationship curve is obtained by polynomial fitting based on the initial permeability at different magnetic field frequencies.

10. A storage medium, characterized in that, The storage medium stores a computer program, which, when executed by a processor, implements the steps of the simulation-inverted method for testing the equivalent conductivity of discontinuous conductive layers according to any one of claims 7-9.

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