Method for testing overall magnetic permeability of shielding layer of magnetic shielding room
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-03-07
- Publication Date
- 2026-08-11
AI Technical Summary
[0003]常见的磁屏蔽房结构是长方体型，其工程建设难度较低；长方体型磁屏蔽房具有边角、孔洞、门体、缝隙等特殊结构，高导磁材料在运输和使用过程中易受到应力、温度、振动等影响，均能导致屏蔽房整体磁导率下降，降低其屏蔽磁场的能力；而现阶段磁屏蔽材料的测试主要使用环形样品来进行测试，只能得到材料在理想状态下的磁导率，其测量结果显著大于磁屏蔽房整体的实际磁导率，导致磁屏蔽房屏蔽效能分析的理论值与实际值偏差较大
[0025]本发明提供了一种磁屏蔽房屏蔽层整体磁导率测试方法，采用在由六块磁屏蔽板拼接而成的长方体的磁屏蔽房为模型进行测量，能够更加真实的还原长方体磁屏蔽房的真实工况，提高长方体型磁屏蔽房磁导率测量的准确性；还采用在长方体屏蔽房上与x向垂直的壁面上的两个棱边上分别设置多个第一穿线孔和多个第二穿线孔，并通过依次穿过相对应的第一穿线孔和第二穿线孔先后在在长方体磁屏蔽房的壁面上绕设初级线圈和次级线圈，并将各个初级线圈串联后与励磁电源连通，各个次级线圈串联后与磁通检测仪器连通，使初级线圈和次级线圈在相对设置的两个壁面上均匀分布，来检测次级线圈中的磁感应通量，获得一组与不同强度电流相对应的磁感应通量集合，然后再通过计算及线性处理，从而得到长方体型磁屏蔽房磁导率，能够进一步的提高长方体型磁屏蔽房磁导率测量的准确性，减少磁屏蔽房屏蔽效能分析的理论值与实际值的偏差。
Smart Images
Figure CN116068469B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of magnetic property measurement technology for magnetic materials, and in particular to a method for testing the overall magnetic permeability of the shielding layer of a magnetically shielded room. Background Technology
[0002] A zero-magnetic-field environment refers to an environment with extremely weak magnetic fields. It has unique applications in measuring weak signals such as heart and brain magnetoencephalograms, measuring geophysical research samples, measuring electric dipole moments, and evaluating high-precision magnetic measuring instruments. Magnetic shielding rooms can utilize the magnetic circuit shunting mechanism of high-permeability materials and the eddy current loss mechanism of high-conductivity materials to shield external magnetic fields and provide a near-zero magnetic field environment. Among them, the ability of magnetic shielding rooms to shield static magnetic fields or low-frequency magnetic fields is mainly determined by the permeability of high-permeability materials.
[0003] The common structure of magnetic shielding rooms is rectangular, which is relatively easy to construct. However, rectangular magnetic shielding rooms have special structures such as corners, holes, doors, and gaps. High magnetic permeability materials are easily affected by stress, temperature, and vibration during transportation and use, all of which can lead to a decrease in the overall magnetic permeability of the shielding room and reduce its ability to shield magnetic fields. At present, the testing of magnetic shielding materials mainly uses toroidal samples, which can only obtain the magnetic permeability of the material under ideal conditions. The measured results are significantly greater than the actual magnetic permeability of the entire magnetic shielding room, resulting in a large deviation between the theoretical and actual values of the shielding effectiveness analysis of the magnetic shielding room. Summary of the Invention
[0004] The purpose of this invention is to provide a method for testing the overall magnetic permeability of the shielding layer of a magnetically shielded room, so as to solve the problems existing in the prior art, improve the accuracy of magnetic permeability measurement of cuboid magnetically shielded rooms, and reduce the deviation between the theoretical and actual values of the shielding effectiveness analysis of magnetically shielded rooms.
[0005] To achieve the above objectives, the present invention provides the following solution:
[0006] This invention provides a method for testing the overall magnetic permeability of the shielding layer of a magnetically shielded room. The magnetically shielded room is rectangular in shape and is composed of six magnetically shielded plates. The method specifically includes the following steps:
[0007] S1: Establish a coordinate system with the center point of the magnetic shielding room as the origin. The xy plane and xz plane on the coordinate system are parallel to the two connected walls of the magnetic shielding room, respectively.
[0008] S2: On one wall perpendicular to the x-direction of the cuboid magnetic shielding room, there are multiple equally spaced first wire holes and multiple equally spaced second wire holes on two parallel edges. The multiple first wire holes correspond one-to-one with the multiple second wire holes. The connecting line between the center of the corresponding first wire hole and the center of the corresponding second wire hole is parallel to the z-axis. The multiple first wire holes and multiple second wire holes connect the interior and exterior of the cuboid magnetic shielding room. The structure on the two walls perpendicular to the x-direction of the cuboid magnetic shielding room is symmetrical about the yz plane.
[0009] S3: A primary coil is wound on the wall of the cuboid magnetic shielding room by passing it through the corresponding first and second wire holes in sequence. A part of the primary coil is located inside the cuboid magnetic shielding room, and the other part of the primary coil is located outside the cuboid magnetic shielding room. Any two adjacent primary coils on the wall are connected in series. The two sets of primary coils connected in series on the two walls perpendicular to the x-direction are connected in series and connected to the excitation power supply.
[0010] S4: Secondary coils are wound on the wall of the cuboid magnetic shielding room by passing them sequentially through the corresponding first and second wire holes. Part of the secondary coil is located inside the cuboid magnetic shielding room, and the other part of the secondary coil is located outside the cuboid magnetic shielding room. Any two adjacent secondary coils on the wall are connected in series. The two sets of series-connected secondary coils on the two walls perpendicular to the x-direction are connected in series and connected to the magnetic flux detector.
[0011] S5: Set different current intensities on the excitation power supply, start the excitation power supply and the magnetic flux detector, measure the internal induced magnetic flux signal in the secondary coil through the magnetic flux detector, and obtain a set of magnetic flux corresponding to different current intensities.
[0012] S6: Calculate H and B using the formulas: Ae = h * d, H = N1I / Le, and B = φ / N2Ae. Plot the (B, H) curve. Then, using the formula μ = B / Hμ0, we know that μ is the ratio of the slope of the (B, H) curve to μ0. Calculate the slope of the (B, H) curve to deduce the overall magnetic permeability μ of the shielding layer of the magnetic shielding room. Here, Le is the magnetic circuit length, the circumference of the plane perpendicular to the winding direction of the primary or secondary coil, Ae is the effective cross-sectional area of the magnetic circuit, h is the distance between the center of the first and second wire holes, d is the thickness of the magnetic shielding plate on the magnetic shielding room, H is the magnetic field strength, N1 is the number of turns of the primary coil, I is the current intensity of the primary coil, B is the magnetic induction intensity of the secondary coil, φ is the magnetic flux density measured by the magnetic flux meter at both ends of the secondary coil, N2 is the number of turns of the secondary coil, and μ0 is the vacuum permeability, μ0 = 4π × 10⁻⁶. -7 H / m.
[0013] Preferably, in step S2, multiple equally spaced first threading holes and multiple equally spaced second threading holes are respectively provided on two parallel edges of one wall surface perpendicular to the z-direction of the cuboid magnetic shielding room, and the multiple first threading holes correspond one-to-one with the multiple second threading holes. The connecting line between the center of the corresponding first threading hole and the center of the corresponding second threading hole is parallel to the y-axis. The structure on the two walls perpendicular to the z-direction of the cuboid magnetic shielding room is symmetrically arranged about the xy plane. Steps S3 to S6 are performed on the first threading holes and second threading holes on the two walls perpendicular to the z-direction to obtain two magnetic permeabilities and then the average value is calculated.
[0014] Preferably, in step S2, multiple equally spaced first threading holes and multiple equally spaced second threading holes are respectively provided on two parallel edges of one wall surface perpendicular to the y-direction of the cuboid magnetic shielding room, and the multiple first threading holes correspond one-to-one with the multiple second threading holes. The connecting line between the center of the corresponding first threading hole and the center of the corresponding second threading hole is parallel to the x-axis. The structure on the two walls perpendicular to the y-direction of the cuboid magnetic shielding room is symmetrically arranged about the xz plane. Steps S3 to S6 are performed on the first threading holes and second threading holes on the two walls perpendicular to the y-direction to obtain three magnetic permeabilities and then the average value is calculated.
[0015] Preferably, in step S2, multiple equally spaced first threading holes and multiple equally spaced second threading holes are respectively provided on two parallel edges of one wall surface perpendicular to the y-direction of the cuboid magnetic shielding room, and the multiple first threading holes correspond one-to-one with the multiple second threading holes. The connecting line between the center of the corresponding first threading hole and the center of the corresponding second threading hole is parallel to the z-axis. The structure on the two walls surface perpendicular to the y-direction of the cuboid magnetic shielding room is symmetrically arranged about the xz plane. The two edges on the two walls surface perpendicular to the x-direction and the two edges on the two walls surface perpendicular to the y-direction are located on the same wall surface.
[0016] In step S3, any two adjacent primary coils on two walls perpendicular to the y direction are connected in series. The two sets of primary coils connected in series on two walls perpendicular to the x direction are connected in series through the primary coil connected in series on one wall perpendicular to the y direction. The primary coil connected in series on one wall perpendicular to the x direction is connected to the excitation power supply through the primary coil connected in series on another wall perpendicular to the y direction.
[0017] In step S4, any two adjacent secondary coils on two walls perpendicular to the y-direction are connected in series. The two sets of secondary coils connected in series on two walls perpendicular to the x-direction are connected in series through a secondary coil connected in series on one wall perpendicular to the y-direction. The secondary coil connected in series on one wall perpendicular to the x-direction is connected to the magnetic flux detector through a secondary coil connected in series on another wall perpendicular to the y-direction.
[0018] Preferably, the number of turns of the secondary coil is 0.5 to 1 times the number of turns of the primary coil.
[0019] Preferably, the spacing between two adjacent secondary coils is 150 to 300 mm.
[0020] Preferably, both the primary coil and the secondary coil are multi-core soft copper wires covered with an insulating layer.
[0021] Preferably, the magnetic shielding plate is a plate made of a high magnetic permeability material.
[0022] Preferably, the cross-sectional area of the primary coil wire harness is 4-16 square millimeters, and the cross-sectional area of the secondary coil wire harness is 0.5-1 square millimeters.
[0023] Preferably, the excitation power supply is a DC power supply or an AC power supply.
[0024] The present invention achieves the following technical effects compared to the prior art:
[0025] This invention provides a method for testing the overall magnetic permeability of the shielding layer of a magnetically shielded room. The method uses a cuboid magnetically shielded room composed of six magnetic shielding plates as a model for measurement, which more realistically reproduces the actual working conditions of the cuboid magnetically shielded room and improves the accuracy of magnetic permeability measurement. Furthermore, multiple first and second threading holes are respectively set on two edges of the wall perpendicular to the x-direction of the cuboid shielded room. A primary coil is wound onto the wall of the cuboid magnetically shielded room by sequentially passing the primary coil through the corresponding first and second threading holes. The primary and secondary coils are connected in series and then connected to the excitation power supply. The secondary coils are also connected in series and then connected to a magnetic flux detection instrument. The primary and secondary coils are evenly distributed on two opposing walls to detect the magnetic flux in the secondary coils. A set of magnetic flux corresponding to different current intensities is obtained. Then, through calculation and linear processing, the permeability of the cuboid magnetic shielding room is obtained. This can further improve the accuracy of the permeability measurement of the cuboid magnetic shielding room and reduce the deviation between the theoretical and actual values of the shielding effectiveness analysis of the magnetic shielding room. Attached Figure Description
[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0027] Figure 1 This is a schematic diagram of the rectangular magnetic shielding room in Example 1;
[0028] Figure 2 This is a schematic diagram of the rectangular magnetic shielding room in Example 2;
[0029] Figure 3 This is a schematic diagram of the rectangular magnetic shielding room in Example 3;
[0030] Figure 4 This is a schematic diagram of the rectangular magnetic shielding room in Example 4. Detailed Implementation
[0031] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0032] The purpose of this invention is to provide a method for testing the overall magnetic permeability of the shielding layer of a magnetically shielded room, so as to solve the problems existing in the prior art, improve the accuracy of magnetic permeability measurement of cuboid magnetically shielded rooms, and reduce the deviation between the theoretical and actual values of the shielding effectiveness analysis of magnetically shielded rooms.
[0033] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.
[0034] Example 1
[0035] This embodiment provides a method for testing the overall magnetic permeability of the shielding layer of a magnetically shielded room. The magnetically shielded room is rectangular in shape and is composed of six magnetic shielding plates. The magnetic shielding plates are made of a high-permeability material. Figure 1 As shown, the specific steps include the following:
[0036] S1: Establish a coordinate system with the center point of the magnetic shielding room as the origin. The xy plane and xz plane on the coordinate system are parallel to the two connected walls of the magnetic shielding room, respectively.
[0037] S2: On one wall perpendicular to the x-direction of the cuboid magnetic shielding room, there are multiple equally spaced first wire holes and multiple equally spaced second wire holes on two parallel edges. The multiple first wire holes correspond one-to-one with the multiple second wire holes. The connecting line between the center of the corresponding first wire hole and the center of the corresponding second wire hole is parallel to the z-axis. The multiple first wire holes and multiple second wire holes connect the interior and exterior of the cuboid magnetic shielding room. The structure on the two walls perpendicular to the x-direction of the cuboid magnetic shielding room is symmetrical about the yz plane.
[0038] S3: A primary coil is wound on the wall of the cuboid magnetic shielding room by passing it through the corresponding first and second wire holes in sequence. A part of the primary coil is located inside the cuboid magnetic shielding room, and the other part of the primary coil is located outside the cuboid magnetic shielding room. Any two adjacent primary coils on the wall are connected in series. The two sets of primary coils connected in series on the two walls perpendicular to the x-direction are connected in series and connected to the excitation power supply.
[0039] S4: Secondary coils are wound on the wall of the cuboid magnetic shielding room by passing them sequentially through the corresponding first and second wire holes. Part of the secondary coil is located inside the cuboid magnetic shielding room, and the other part of the secondary coil is located outside the cuboid magnetic shielding room. Any two adjacent secondary coils on the wall are connected in series. The two sets of series-connected secondary coils on the two walls perpendicular to the x-direction are connected in series and connected to the magnetic flux detector.
[0040] S5: Set different current intensities on the excitation power supply, start the excitation power supply and the magnetic flux detector, measure the internal induced magnetic flux signal in the secondary coil through the magnetic flux detector, and obtain a set of magnetic flux corresponding to different current intensities.
[0041] S6: Calculate H and B using the formulas: Ae=h*d, H=N1I / Le, and B=φ / N2Ae. Plot the (B, H) curve. Then, using the formula μ=B / Hμ0, we know that μ is the ratio of the slope of the (B, H) curve to μ0. Calculate the slope of the (B, H) curve to deduce the overall magnetic permeability μ of the magnetic shielding layer, where Le is the magnetic circuit length, which is the circumference of the plane perpendicular to the winding direction of the primary or secondary coil, i.e., the circumference of the plane perpendicular to the first through hole. The wall surface perpendicular to the line connecting the center of the first and second wire holes; Ae is the effective cross-sectional area of the magnetic circuit; h is the distance between the centers of the first and second wire holes; d is the thickness of the magnetic shielding plate on the magnetic shielding room; H is the magnetic field strength; N1 is the number of turns of the primary coil; I is the current intensity of the primary coil; B is the magnetic induction intensity of the secondary coil; φ is the magnetic flux density measured by the magnetic flux meter across the secondary coil; N2 is the number of turns of the secondary coil; μ0 is the permeability of free space; μ0 = 4π × 10⁻⁶. -7 H / m.
[0042] Specifically, the number of turns of the secondary coil is 0.5 to 1 times that of the primary coil, preferably 0.8 to 1 times, and even more preferably 1 times; the spacing between two adjacent secondary coils is 150 to 300 mm, preferably 200 to 280 mm, and even more preferably 250 mm; the wire harnesses of both the primary and secondary coils are multi-core soft copper wires with insulation layers; the cross-sectional area of the primary coil wire harness is 4-16 square millimeters, preferably 8-12 square millimeters, and even more preferably 10 square millimeters, and the cross-sectional area of the secondary coil wire harness is 0.5-1 square millimeters, preferably 0.6-0.8 square millimeters, and even more preferably 0.5 square millimeters; the excitation power supply is a DC power supply or an AC power supply.
[0043] In the specific implementation process, taking a cube-shaped magnetically shielded room with a side length of a = 0.5m and a magnetic shielding plate thickness of 3mm as an example, the demagnetizing wire bundle of the primary coil is a 4 square millimeter multi-core soft copper wire, and the magnetic induction wire bundle of the secondary coil is a 0.5 square millimeter multi-core soft copper wire as an example, for illustration. Figure 1 As shown, the steps are as follows:
[0044] S1: Establish a coordinate system with the center point of the magnetic shielding room as the origin. The xy plane and xz plane on the coordinate system are parallel to the two connected walls B1B7B5B3 and B7B5A5A7 on the magnetic shielding room, respectively.
[0045] S2: On the rectangular magnetic shielding room, on walls A7A1B1B7 and A3A5B5B3 perpendicular to the x-direction, three equally spaced first wiring holes A7, A8, A1 and three equally spaced second wiring holes B1, B8, B7 are respectively provided on the edges A7A1 and B1B7 of wall A7A1B1B7. The three first wiring holes correspond one-to-one with the three second wiring holes, that is, A7 corresponds to B7, A8 corresponds to B8, and A1 corresponds to B1. The edges of wall A3A5B5B3... Three equally spaced first wire holes A3, A4, A5 and three equally spaced second wire holes B3, B4, B5 are respectively provided on the edges A3A5 and B5B3. The three first wire holes and the three second wire holes correspond one-to-one, that is, A5 and B5 correspond, A4 and B4 correspond, and A3 and B3 correspond. The connecting line between the center of the corresponding first wire hole and the center of the second wire hole is parallel to the z-axis. The multiple first wire holes and multiple second wire holes are connected to the interior and exterior of the cuboid magnetic shielding room.
[0046] S3: A primary coil is wound on the wall of the cuboid magnetic shielding room by passing it through the corresponding first and second wire holes in sequence. A part of the primary coil is located inside the cuboid magnetic shielding room, and the other part of the primary coil is located outside the cuboid magnetic shielding room. Any two adjacent primary coils on the wall are connected in series. The two sets of primary coils connected in series on the two walls perpendicular to the x-direction are connected in series and connected to the excitation power supply.
[0047] The specific winding method of the primary coil is as follows: The demagnetizing wire runs along the inside of the magnetically shielded room from A1 to B1, passes through the second wire hole B1, then runs along the outside of the shielding layer from B1 to A1, and then passes through the first wire hole A1 into the magnetically shielded room. This constitutes one turn. The primary coil is wound in the above manner, for a total of 12 turns. Then, from the inside of the magnetically shielded room, from A1 to A8, the primary coil is wound 12 turns between the first wire hole A8 and the second wire hole B8. Then, from the inside of the magnetically shielded room, from A8 to A7, the primary coil is wound 12 turns between the first wire hole A7 and the second wire hole B7. From the inside of the magnetically shielded room, from A7 to A5, a primary coil of 12 turns is wound between the first wire hole A5 and the second wire hole B5. Then, from the inside of the magnetically shielded room, from A5 to A4, a primary coil of 12 turns is wound between the first wire hole A4 and the second wire hole B4. Then, from the inside of the magnetically shielded room, from A4 to A3, a primary coil of 12 turns is wound between the first wire hole A3 and the second wire hole B3. This completes the setup of multiple primary coils connected in series. The demagnetizing currents on the inside and outside of the magnetically shielded room are of the same magnitude but opposite in direction. Only the demagnetizing line and current direction on the outside are shown in the figure.
[0048] S4: Secondary coils are wound on the wall of the cuboid magnetic shielding room by passing them sequentially through the corresponding first and second wire holes. Part of the secondary coil is located inside the cuboid magnetic shielding room, and the other part of the secondary coil is located outside the cuboid magnetic shielding room. Any two adjacent secondary coils on the wall are connected in series. The two sets of series-connected secondary coils on the two walls perpendicular to the x-direction are connected in series and connected to the magnetic flux detector.
[0049] The specific winding method for the secondary coil is as follows: Magnetic induction lines run along the inner side of the magnetically shielded room from A1 to B1, pass through the second wire hole B1, then run along the outer side of the shielding layer from B1 to A1, and then pass through the first wire hole A1 into the magnetically shielded room. This constitutes one turn. The secondary coil is wound in the above manner, for a total of 12 turns. Then, from the inner side of the magnetically shielded room, from A1 to A8, the secondary coil is wound 12 turns between the first wire hole A8 and the second wire hole B8. Finally, from the inner side of the magnetically shielded room, from A8 to A7, the secondary coil is wound between the first wire hole A7 and the second wire hole B7. The secondary coil has 12 turns. Then, from the inside of the magnetic shielding room, from A7 to A5, the secondary coil has 12 turns wound between the first wire hole A5 and the second wire hole B5. Then, from the inside of the magnetic shielding room, from A5 to A4, the secondary coil has 12 turns wound between the first wire hole A4 and the second wire hole B4. Then, from the inside of the magnetic shielding room, from A4 to A3, the secondary coil has 12 turns wound between the first wire hole A3 and the second wire hole B3. This completes the setup of multiple secondary coils connected in series. The demagnetizing current on the inside and outside of the magnetic shielding room is the same in magnitude but opposite in direction.
[0050] S5: Set different current intensities on the excitation power supply, with 10 increments between 0.013A and 13A. Start the excitation power supply and the magnetic flux detector. Measure the internal induced magnetic flux signal in the secondary coil through the magnetic flux detector to obtain a set of 10 magnetic flux values corresponding to different current intensities.
[0051] S6: Le is the magnetic circuit length, which is the circumference of the plane B1B3B5B7 perpendicular to the winding direction of the primary or secondary coil, 4a = 2m;
[0052] According to Ae = h * d, where h is the distance a between the center of the first threading hole and the center of the second threading hole, Ae = 1.5 × 10 -3 mm 2 ;
[0053] Based on H = N1I / Le, N1 = 12, and taking 10 values for the current I from 0.013A to 13A, calculate the corresponding 10 magnetic field strengths H;
[0054] Based on B=φ / N2Ae, N2=12, the corresponding magnetic flux density B of the 10 secondary coils is calculated based on the 10 measured magnetic flux values.
[0055] Thus, the (B, H) curve is plotted; according to the formula μ=B / Hμ0, μ is the ratio of the slope of the (B, H) curve to μ0; based on the (B, H) curve, the slope of the (B, H) curve is calculated, and the overall magnetic permeability μ of the shielding layer of the magnetic shielding room is derived.
[0056] In the above embodiments, a rectangular magnetic shielding room composed of six magnetic shielding plates is used as a model for measurement. This method can more realistically reproduce the actual working conditions of the rectangular magnetic shielding room and improve the accuracy of the magnetic permeability measurement. Furthermore, multiple first and second threading holes are respectively set on two edges of the wall perpendicular to the x-direction of the rectangular magnetic shielding room. Primary and secondary coils are wound sequentially through the corresponding first and second threading holes on the wall of the rectangular magnetic shielding room. The primary coils are connected in series and then connected to the excitation power supply. The secondary coils are connected in series and then connected to the magnetic flux detection instrument. This ensures that the primary and secondary coils are evenly distributed on the two opposing wall surfaces, allowing the detection of the magnetic flux in the secondary coils. A set of magnetic flux corresponding to different current intensities is obtained. Then, through calculation and linear processing, the magnetic permeability of the rectangular magnetic shielding room is obtained. This further improves the accuracy of the magnetic permeability measurement and reduces the deviation between the theoretical and actual values of the shielding effectiveness analysis.
[0057] Example 2
[0058] This embodiment provides a method for testing the overall magnetic permeability of the shielding layer of a magnetically shielded room. The only difference from Embodiment 1 is that: on one wall surface perpendicular to the z-direction of the cuboid magnetically shielded room, multiple equally spaced first through holes and multiple equally spaced second through holes are respectively provided on two parallel edges. The multiple first through holes correspond one-to-one with the multiple second through holes. The connecting line between the center of the corresponding first through hole and the center of the corresponding second through hole is parallel to the y-axis. The structure on the two walls perpendicular to the z-direction of the cuboid magnetically shielded room is symmetrically arranged about the xy plane. Steps S3 to S6 are performed on the first through holes and second through holes on the two walls perpendicular to the z-direction, respectively. After obtaining two permeabilities, the average value is calculated. It is worth noting that the two permeabilities here are the permeabilities measured between the primary coils on the two walls perpendicular to the x-direction and the permeabilities measured between the primary coils on the two walls perpendicular to the z-direction.
[0059] In the specific implementation process, such as Figure 2As shown, three equally spaced first wire holes A7, A6, and A5 and three equally spaced second wire holes A3, A2, and A1 are respectively provided on the edges A7A5 and A3A1 of wall surface A7A5A3A1. The three first wire holes and the three second wire holes correspond one-to-one, that is, A7 corresponds to A1, A6 corresponds to A2, and A5 corresponds to A3. Similarly, three equally spaced first wire holes B5, A6, and B7 and three equally spaced second wire holes B3, B2, and B1 are respectively provided on the edges B5B7 and B1B3 of wall surface B5B7B1B7. The three first wire holes and the three second wire holes correspond one-to-one, that is, B5 corresponds to B3, A6 corresponds to B2, and B7 corresponds to B1. The connecting line between the center of the corresponding first wire hole and the center of the second wire hole is parallel to the y-axis. All the first wire holes and the multiple second wire holes connect the interior and exterior of the cuboid magnetic shielding room.
[0060] The specific winding method of the primary coil on the wall perpendicular to the z-axis is as follows: The demagnetizing wire runs along the inside of the magnetically shielded room from A5 to A3, passes through the second wire hole A3, then runs along the outside of the shielding layer from A3 to A5, and then passes through the first wire hole A5 into the magnetically shielded room. This is one turn. The primary coil is wound in the above manner, for a total of 12 turns. Then, from the inside of the magnetically shielded room from A5 to A6, the primary coil is wound 12 turns between the first wire hole A6 and the second wire hole A2. Finally, from the inside of the magnetically shielded room from A6 to A7, the primary coil is wound between the first wire hole A7 and the second wire hole A1. 12 turns. Then, from the inside of the magnetic shielding room, from A7 to B7, wind the primary coil 12 turns between the first wire hole B7 and the second wire hole B1. Then, from the inside of the magnetic shielding room, from B7 to B7, wind the primary coil 12 turns between the first wire hole B6 and the second wire hole B2. Then, from the inside of the magnetic shielding room, from B6 to B5, wind the primary coil 12 turns between the first wire hole B5 and the second wire hole B3. This completes the setup of multiple primary coils connected in series. The demagnetizing wires on the inside and outside of the magnetic shielding room have the same magnitude but opposite directions of current. Only the demagnetizing wires and current direction on the outside are shown in the figure.
[0061] The winding method of the secondary coil on the wall perpendicular to the z-axis is the same as that of the primary coil on the wall perpendicular to the z-axis.
[0062] It is worth noting that the magnetic circuit length Le on the two walls perpendicular to the z-axis is the perimeter of wall A1A3B3B1, and h is the length of A6A2.
[0063] In the above embodiment, by measuring the magnetic flux of two sets of opposing walls, with the primary coils of the two sets of walls being designed to be perpendicular to each other, the permeability of the cuboid magnetic shielding room in two directions can be obtained. Then, by averaging the values, the accuracy of the permeability measurement of the cuboid magnetic shielding room can be further improved, and the deviation between the theoretical and actual values of the shielding effectiveness analysis of the magnetic shielding room can be reduced.
[0064] Example 3
[0065] This embodiment provides a method for testing the overall magnetic permeability of the shielding layer of a magnetically shielded room. The difference from Embodiment 2 is only that: in step S1, multiple equally spaced first wire holes and multiple equally spaced second wire holes are respectively provided on two parallel edges of a wall perpendicular to the y-direction on the cuboid magnetically shielded room. The multiple first wire holes and multiple second wire holes correspond one-to-one. The connecting line between the center of the corresponding first wire hole and the center of the corresponding second wire hole is parallel to the x-axis. The structure on the two walls perpendicular to the y-direction on the cuboid magnetically shielded room is symmetrically arranged about the xz plane. Steps S3 to S6 are performed on the first wire holes and second wire holes on the two walls perpendicular to the y-direction respectively. After obtaining three magnetic permeabilities, the average value is calculated. The three magnetic permeabilities here are the magnetic permeability measured between the primary coils on the two walls perpendicular to the x-direction, the magnetic permeability measured between the primary coils on the two walls perpendicular to the z-direction, and the magnetic permeability measured between the primary coils on the two walls perpendicular to the y-direction.
[0066] In the specific implementation process, such as Figure 3 As shown, walls A3B3B1A1 and B5A5A7B7 are two walls perpendicular to the y-direction. Three equally spaced first threading holes A3, C2, and B3 and three equally spaced second threading holes A1, C1, and B1 are respectively provided on the edges A3B3 and B1A1 of wall A3B3B1A1. The three first threading holes correspond one-to-one with the three second threading holes, i.e., A3 corresponds to A1, C2 to C1, and B3 to B1. The edge B1A1 of wall B5A5A7B7... Three equally spaced first wire-passing holes B5, C3, and A5 and three equally spaced second wire-passing holes B7, C4, and A7 are respectively provided on 5A5 and edge A7B7. The three first wire-passing holes and the three second wire-passing holes correspond one-to-one, that is, B5 and B7 correspond, C3 and C4 correspond, and A5 and A7 correspond. The connecting line between the center of the corresponding first wire-passing hole and the center of the second wire-passing hole is parallel to the x-direction. The multiple first wire-passing holes and the multiple second wire-passing holes all connect the interior and exterior of the cuboid magnetic shielding room.
[0067] The specific winding method of the primary coil on the wall perpendicular to the y-direction is as follows: The demagnetizing wire runs along the inside of the magnetically shielded room from B3 to B1, passes through the second wire hole B1, then runs along the outside of the shielding layer from B1 to B3, and then passes through the first wire hole B3 into the magnetically shielded room. This is one turn. The primary coil is wound in the above manner, for a total of 12 turns. Then, from the inside of the magnetically shielded room, from B3 to C2, the primary coil is wound 12 turns between the first wire hole C2 and the second wire hole C1. Finally, from the inside of the magnetically shielded room, from C2 to A3, the primary coil is wound between the first wire hole A3 and the second wire hole A1. 12 turns. Then, from the inside of the magnetic shielding room, from A3 to A5, wind the primary coil 12 turns between the first wire hole A5 and the second wire hole A7. Then, from the inside of the magnetic shielding room, from A5 to C3, wind the primary coil 12 turns between the first wire hole C3 and the second wire hole C4. Then, from the inside of the magnetic shielding room, from C3 to B5, wind the primary coil 12 turns between the first wire hole B5 and the second wire hole B7. This completes the setup of multiple primary coils connected in series. The demagnetizing wires on the inside and outside of the magnetic shielding room have the same magnitude but opposite directions of current. Only the demagnetizing wires and current direction on the outside are shown in the figure.
[0068] The winding method of the secondary coil on the wall perpendicular to the y-direction is the same as that of the primary coil on the wall perpendicular to the y-direction.
[0069] It is worth noting that the magnetic circuit length Le of the wall perpendicular to the y-direction is the perimeter of the wall A1B1B7A7, and h is the length of C1C2.
[0070] In the above embodiment, by measuring the magnetic flux of three sets of oppositely arranged walls, with the primary coils of any two sets of walls being designed to be perpendicular to each other, the permeability of the cuboid magnetic shielding room in three directions can be obtained. Then, by averaging the values, the accuracy of the permeability measurement of the cuboid magnetic shielding room can be further improved, and the deviation between the theoretical and actual values of the shielding effectiveness analysis of the magnetic shielding room can be reduced.
[0071] Example 4
[0072] This embodiment provides a method for testing the overall magnetic permeability of the shielding layer of a magnetically shielded room. The only difference from Embodiment 1 is that in step S2, multiple equally spaced first threading holes and multiple equally spaced second threading holes are respectively provided on two parallel edges of a wall perpendicular to the y-direction on the cuboid magnetically shielded room. The multiple first threading holes and multiple second threading holes correspond one-to-one. The connecting line between the center of the corresponding first threading hole and the center of the corresponding second threading hole is parallel to the z-axis. The structure on the two walls perpendicular to the y-direction on the cuboid magnetically shielded room is symmetrically arranged about the xz plane. The two edges on the two walls perpendicular to the x-direction and the two edges on the two walls perpendicular to the y-direction are located on the same wall.
[0073] In step S3, any two adjacent primary coils on two walls perpendicular to the y direction are connected in series. The two sets of primary coils connected in series on two walls perpendicular to the x direction are connected in series through the primary coil connected in series on one wall perpendicular to the y direction. The primary coil connected in series on one wall perpendicular to the x direction is connected to the excitation power supply through the primary coil connected in series on another wall perpendicular to the y direction.
[0074] In step S4, any two adjacent secondary coils on two walls perpendicular to the y-direction are connected in series. The two sets of secondary coils connected in series on two walls perpendicular to the x-direction are connected in series through a secondary coil connected in series on one wall perpendicular to the y-direction. The secondary coil connected in series on one wall perpendicular to the x-direction is connected to the magnetic flux detector through a secondary coil connected in series on another wall perpendicular to the y-direction.
[0075] In the specific implementation process, such as Figure 4 As shown, the two edges A7A1 and A3A5 on the two walls A1B1B7A7 and the two edges A7A1 and A3A5 on the wall A3B3B5A5 are all located on one wall A5A3A1A7 of the cuboid magnetic shielding room. Multiple primary coils connected in series on the two walls A1B1B7A7 and A3B3B5A5 (perpendicular to the x-direction) are connected in series through the primary coil connected in series on one of the two walls A1A3B3B1 and A5A7B7B5 (perpendicular to the y-direction). Similarly, multiple primary coils connected in series on one of the two walls A1B1B7A7 and A3B3B5A5 (perpendicular to the x-direction) are connected in series through the two edges A1A3B3B1 and A5A7B7B5 (perpendicular to the y-direction). The primary coil, connected in series on another wall A1A3B3B1 among walls A1A3B3B1 and A5A7B7B5, is connected to the excitation power supply. Multiple secondary coils, connected in series on two walls A1B1B7A7 and A3B3B5A5 perpendicular to the x-direction, are connected in series on one of the two walls A1A3B3B1 and A5A7B7B5 perpendicular to the y-direction. Multiple secondary coils, connected in series on one of the two walls A1B1B7A7 and A3B3B5A5 perpendicular to the x-direction, are connected in series on another of the two walls A1A3B3B1 and A5A7B7B5 perpendicular to the y-direction, and are connected to the magnetic flux detector.
[0076] Winding method of the primary coil: The demagnetizing wire runs along the inside of the magnetically shielded room from A3 to B3, passes through the second wire hole B3, then runs along the outside of the shielding layer from B3 to A3, and then passes through the first wire hole A3 into the magnetically shielded room. This is one turn. The primary coil is wound in the above manner, for a total of 12 turns. Then, from the inside of the magnetically shielded room, from A3 to A2, the primary coil is wound 12 turns between the first wire hole A2 and the second wire hole B2. Next, from the inside of the magnetically shielded room, from A2 to A1, the primary coil is wound 12 turns between the first wire hole A1 and the second wire hole B1. Then, from the inside of the magnetically shielded room, from A1 to A8, the primary coil is wound 12 turns between the first wire hole A8 and the second wire hole B8. Finally, from the magnetic... Inside the shielded room, from A8 to A7, a primary coil of 12 turns is wound between the first wire hole A7 and the second wire hole B7. Then, inside the magnetic shielded room, from A7 to A6, a primary coil of 12 turns is wound between the first wire hole A6 and the second wire hole B6. Then, inside the magnetic shielded room, from A6 to A5, a primary coil of 12 turns is wound between the first wire hole A5 and the second wire hole B5. Then, inside the magnetic shielded room, from A5 to A4, a primary coil of 12 turns is wound between the first wire hole A4 and the second wire hole B4. This completes the setup of multiple primary coils connected in series. The demagnetizing currents on the inner and outer sides of the magnetic shielded room are of the same magnitude but opposite in direction. Only the demagnetizing line and current direction on the outer side are shown in the figure.
[0077] The winding method for the secondary coil is the same as that for the primary coil.
[0078] The above embodiments, by evenly distributing primary and secondary coils around the circumference of the rectangular magnetic shielding room, can obtain a more stable and uniform magnetic field strength and magnetic flux, improve the accuracy of magnetic permeability measurement of the rectangular magnetic shielding room, and reduce the deviation between theoretical and actual values in the analysis of the shielding effectiveness of the magnetic shielding room.
[0079] Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. Furthermore, those skilled in the art will recognize that, based on the ideas of this invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this invention.
Claims
1. A method for testing the overall magnetic permeability of the shielding layer of a magnetically shielded room, wherein the magnetically shielded room is rectangular in shape and is composed of six magnetically shielded plates, characterized in that: Includes the following steps: S1: Establish a coordinate system with the center point of the magnetic shielding room as the origin. The xy plane and xz plane on the coordinate system are parallel to the two connected walls of the magnetic shielding room, respectively. S2: On one wall perpendicular to the x-direction of the cuboid magnetic shielding room, there are multiple equally spaced first wire holes and multiple equally spaced second wire holes on two parallel edges. The multiple first wire holes correspond one-to-one with the multiple second wire holes. The connecting line between the center of the corresponding first wire hole and the center of the corresponding second wire hole is parallel to the z-axis. The multiple first wire holes and multiple second wire holes connect the interior and exterior of the cuboid magnetic shielding room. The structure on the two walls perpendicular to the x-direction of the cuboid magnetic shielding room is symmetrical about the yz plane. S3: A primary coil is wound on the wall of the cuboid magnetic shielding room by passing it through the corresponding first and second wire holes in sequence. A part of the primary coil is located inside the cuboid magnetic shielding room, and the other part of the primary coil is located outside the cuboid magnetic shielding room. Any two adjacent primary coils on the wall are connected in series. The two sets of primary coils connected in series on the two walls perpendicular to the x-direction are connected in series and connected to the excitation power supply. S4: Secondary coils are wound on the wall of the cuboid magnetic shielding room by passing them sequentially through the corresponding first and second wire holes. Part of the secondary coil is located inside the cuboid magnetic shielding room, and the other part of the secondary coil is located outside the cuboid magnetic shielding room. Any two adjacent secondary coils on the wall are connected in series. The two sets of series-connected secondary coils on the two walls perpendicular to the x-direction are connected in series and connected to the magnetic flux detector. S5: Set different current intensities on the excitation power supply, start the excitation power supply and the magnetic flux detector, measure the internal induced magnetic flux signal in the secondary coil through the magnetic flux detector, and obtain a set of magnetic flux corresponding to different current intensities. S6: Calculate H and B using the formulas: Ae = h * d, H = N1I / Le, and B = φ / N2Ae. Plot the (B, H) curve. Then, using the formula μ = B / Hμ0, we know that μ is the ratio of the slope of the (B, H) curve to μ0. Calculate the slope of the (B, H) curve to deduce the overall magnetic permeability μ of the shielding layer of the magnetic shielding room. Here, Le is the magnetic circuit length, the circumference of the plane perpendicular to the winding direction of the primary or secondary coil, Ae is the effective cross-sectional area of the magnetic circuit, h is the distance between the center of the first and second wire holes, d is the thickness of the magnetic shielding plate on the magnetic shielding room, H is the magnetic field strength, N1 is the number of turns of the primary coil, I is the current intensity of the primary coil, B is the magnetic induction intensity of the secondary coil, φ is the magnetic flux density measured by the magnetic flux meter at both ends of the secondary coil, N2 is the number of turns of the secondary coil, and μ0 is the vacuum permeability, μ0 = 4π × 10⁻⁶. -7 H / m.
2. The method for testing the overall magnetic permeability of the shielding layer of a magnetically shielded room according to claim 1, characterized in that: In step S2, multiple equally spaced first threading holes and multiple equally spaced second threading holes are respectively set on two parallel edges of one wall surface perpendicular to the z-direction of the cuboid magnetic shielding room. The multiple first threading holes correspond one-to-one with the multiple second threading holes. The connecting line between the center of the corresponding first threading hole and the center of the corresponding second threading hole is parallel to the y-axis. The structure on the two walls perpendicular to the z-direction of the cuboid magnetic shielding room is symmetrically arranged about the xy plane. Steps S3 to S6 are performed on the first threading holes and second threading holes on the two walls perpendicular to the z-direction respectively to obtain two magnetic permeabilities and then calculate the average value.
3. The method for testing the overall magnetic permeability of the shielding layer of a magnetically shielded room according to claim 2, characterized in that: In step S2, multiple equally spaced first threading holes and multiple equally spaced second threading holes are respectively set on two parallel edges of one wall surface perpendicular to the y-direction of the cuboid magnetic shielding room. The multiple first threading holes correspond one-to-one with the multiple second threading holes. The connecting line between the center of the corresponding first threading hole and the center of the corresponding second threading hole is parallel to the x-axis. The structure on the two walls perpendicular to the y-direction of the cuboid magnetic shielding room is symmetrically arranged about the xz plane. Steps S3 to S6 are performed on the first threading holes and second threading holes on the two walls perpendicular to the y-direction to obtain three magnetic permeabilities and then the average value is calculated.
4. The method for testing the overall magnetic permeability of the shielding layer of a magnetically shielded room according to claim 1, characterized in that: In step S2, multiple equally spaced first wire holes and multiple equally spaced second wire holes are respectively provided on two parallel edges of one wall perpendicular to the y-direction of the cuboid magnetic shielding room. The multiple first wire holes correspond one-to-one with the multiple second wire holes. The connecting line between the center of the corresponding first wire hole and the center of the corresponding second wire hole is parallel to the z-axis. The structure on the two walls perpendicular to the y-direction of the cuboid magnetic shielding room is symmetrical about the xz plane. The two edges on the two walls perpendicular to the x-direction and the two edges on the two walls perpendicular to the y-direction are located on the same wall. In step S3, any two adjacent primary coils on two walls perpendicular to the y direction are connected in series. The two sets of primary coils connected in series on two walls perpendicular to the x direction are connected in series through the primary coil connected in series on one wall perpendicular to the y direction. The primary coil connected in series on one wall perpendicular to the x direction is connected to the excitation power supply through the primary coil connected in series on another wall perpendicular to the y direction. In step S4, any two adjacent secondary coils on two walls perpendicular to the y-direction are connected in series. The two sets of secondary coils connected in series on two walls perpendicular to the x-direction are connected in series through a secondary coil connected in series on one wall perpendicular to the y-direction. The secondary coil connected in series on one wall perpendicular to the x-direction is connected to the magnetic flux detector through a secondary coil connected in series on another wall perpendicular to the y-direction.
5. The method for testing the overall magnetic permeability of the shielding layer of a magnetically shielded room according to any one of claims 1 to 4, characterized in that: The number of turns of the secondary coil is 0.5 to 1 times that of the primary coil.
6. The method for testing the overall magnetic permeability of the shielding layer of a magnetically shielded room according to any one of claims 1 to 4, characterized in that: The spacing between two adjacent secondary coils is 150–300 mm.
7. The method for testing the overall magnetic permeability of the shielding layer of a magnetically shielded room according to any one of claims 1 to 4, characterized in that: Both the primary coil and the secondary coil are multi-core soft copper wires covered with an insulating layer.
8. The method for testing the overall magnetic permeability of the shielding layer of a magnetically shielded room according to claim 1, characterized in that: The magnetic shielding plate is made of a high magnetic permeability material.
9. The method for testing the overall magnetic permeability of the shielding layer of a magnetically shielded room according to any one of claims 1 to 4, characterized in that: The cross-sectional area of the primary coil wire harness is 4-16 square millimeters, and the cross-sectional area of the secondary coil wire harness is 0.5-1 square millimeters.
10. The method for testing the overall magnetic permeability of the shielding layer of a magnetically shielded room according to claim 1, characterized in that: The excitation power supply is a DC power supply or an AC power supply.