Active and passive combined type magnetic shielding device and method

Abstract

The invention discloses an active and passive combined type magnetic shielding device which comprises an active shielding assembly and a magnetic shielding cylinder. The active shielding assembly comprises an electrified feedback coil, and the feedback coil is used for generating a counteracting three-dimensional magnetic field which is equal to three components of the low-frequency interference magnetic field in size and opposite in direction so as to counteract the low-frequency interference magnetic field; the magnetic shielding cylinder is arranged in the feedback coil, located in a magnetic field uniform area of the feedback coil and used for shielding a high-frequency interference magnetic field. The active magnetic shielding feedback coil uniform area can cover the whole magnetic shielding cylinder, the internal uniform area of the magnetic field is large, three-axis space magnetic shielding can be achieved, the shielding bandwidth of the magnetic shielding system is widened, and the performance of the magnetic shielding system is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of magnetic shielding, and in particular relates to an active-passive composite magnetic shielding device and method. Background Art

[0002] When calibrating magnetic sensors such as fluxgate and TMR, it is necessary to reproduce multiple standard high-stability magnetic fields. Conventional laboratories are difficult to meet the calibration requirements due to the fluctuations in the surrounding magnetic field environment and the influence of the geomagnetic field, and magnetic shielding is required.

[0003] The passive magnetic shielding system uses high magnetic permeability materials such as Permalloy as the magnetic shielding layer. It has a good magnetic shielding effect against industrial frequency and high-frequency fluctuating interference magnetic fields, but its shielding performance against low-frequency interference magnetic fields such as subways, vehicles, and elevators is poor.

[0004] The active degaussing system uses the principle of magnetic field negative feedback to offset the fluctuating interference magnetic field. It is usually composed of a magnetic sensor, a control circuit, a voltage processing module, and a feedback coil. Active magnetic shielding has excellent shielding performance against low-frequency interference magnetic fields, but poor performance against high-frequency interference magnetic fields.

[0005] The active-passive composite magnetic shielding system is a composite of active magnetic shielding and passive magnetic shielding. Therefore, the active magnetic shielding and passive magnetic shielding are coupled to shield the alternating interference magnetic field. The shielding bandwidth of the magnetic shielding system is expanded by complementing the shielding frequency band to achieve the required high-stability magnetic environment. Composite magnetic shielding systems are required in many fields such as cold atom systems, ion beam processing systems, quantum computers, constant magnetic field reproduction, sensor calibration, transmission electron microscopes (TEM), electron beam equipment, ion probes, etc.

[0006] In order to carry out active and passive composite magnetic shielding, passive shielding is usually placed on the outermost layer, and active shielding is placed inside it. Thereby achieving the purpose of active and passive composite magnetic shielding. There are two common forms: active magnetic shielding built into the shielding tube (passive magnetic screen) and active magnetic shielding built into the shielding room. There are two main problems with the existing composite magnetic shielding with built-in active magnetic shielding in the shielding tube (passive magnetic screen): First, when the active magnetic shielding is built-in, the coil required for the active magnetic shielding needs to be placed inside the shielding tube. The built-in coil will lead to the reduction of the uniform area inside the magnetic shielding tube, thereby reducing the uniform area of ​​the composite magnetic shielding system. On the basis of the existing shielding tube diameter, the size of the device under test is further limited. Second, when the active magnetic shielding is built-in, the feedback coil constructed usually only has the axial direction of the shielding tube, that is, the active magnetic shielding in a single direction, and the three-axis space active magnetic shielding cannot be achieved. Summary of the invention

[0007] In view of this, the present invention provides an active and passive composite magnetic shielding device and method, in which the uniform area of ​​the feedback coil of the active magnetic shielding can cover the entire magnetic shielding tube, the uniform area inside the magnetic field is large, and three-axis spatial magnetic shielding can be achieved, thereby broadening the shielding bandwidth of the magnetic shielding system and improving the performance of the magnetic shielding system.

[0008] The present invention is achieved through the following technical solutions:

[0009] An active-passive composite magnetic shielding device comprises: an active shielding component and a magnetic shielding cylinder;

[0010] The active shielding assembly includes a powered feedback coil, the feedback coil is used to generate a three-dimensional magnetic field that is equal in magnitude to the three components of the low-frequency interference magnetic field and opposite in direction to offset the low-frequency interference magnetic field;

[0011] The magnetic shielding tube is arranged in the feedback coil and is located in the magnetic field uniformity area of ​​the feedback coil, and is used for shielding high-frequency interference magnetic field.

[0012] Furthermore, the active shielding component also includes a magnetic sensor and a control component; the control component is electrically connected to the magnetic sensor and the feedback coil respectively;

[0013] The magnetic sensor is located in the uniform area of ​​the feedback coil, and is used to obtain the three-dimensional magnetic field size data in the uniform area of ​​the feedback coil in real time, and transmit the magnetic field size data to the control component;

[0014] The control component can output a corresponding analog current to the feedback coil according to the three-dimensional magnetic field size data, so that the feedback coil generates a corresponding offset three-dimensional magnetic field.

[0015] Further, the control component includes a control system and a voltage processing module;

[0016] The control system calculates and offsets the interfering magnetic field and outputs the corresponding analog voltage;

[0017] The voltage processing module is electrically connected between the feedback coil and the control system. The voltage processing module is used to amplify the analog voltage and convert it into a corresponding analog current and supply power to the feedback coil.

[0018] Further, the feedback coil is composed of a three-axis coil frame and a three-axis winding;

[0019] The feedback coil is composed of one or more of a Helmholtz coil, a Buckel coil, a Brownberg coil, a Gartler coil, a Maxwell coil and a pitch-free coil.

[0020] An active-passive composite magnetic shielding method is based on an active-passive composite magnetic shielding device, and the method is as follows:

[0021] The magnetic shielding tube is arranged inside the feedback coil and is located in the magnetic field uniformity area of ​​the feedback coil to passively shield the high-frequency interference magnetic field;

[0022] The magnetic sensor obtains the three-dimensional magnetic field size data in the uniform area of ​​the feedback coil in real time and transmits it to the control component. The control system of the control component receives the three-dimensional magnetic field size data and calculates and outputs the corresponding analog voltage according to the three-dimensional magnetic field size data.

[0023] The voltage processing module of the control component amplifies the analog voltage and converts it into a corresponding analog current to provide to the feedback coil;

[0024] The feedback coil generates in real time a cancelling interference magnetic field that is equal in magnitude to the three components of the low-frequency interference magnetic field and opposite in direction, thereby actively cancelling out the low-frequency interference magnetic field.

[0025] Beneficial effects:

[0026] (1) The present invention provides an active-passive composite magnetic shielding device, in which a magnetic shielding tube is arranged inside a feedback coil. On the one hand, the size of the feedback coil does not need to be limited by the space of the magnetic shielding tube, which facilitates the realization of active magnetic shielding in three-dimensional space. On the other hand, the uniform area of ​​the feedback coil can cover the entire magnetic shielding tube. The uniform area is large, and the size of the device under test is only limited by the diameter of the shielding tube, and does not need to be limited by the uniform area of ​​the feedback coil, which facilitates the calibration of the device under test.

[0027] (2) The magnetic sensor of the present invention can obtain the three-dimensional magnetic field size data in the uniform area of ​​the feedback coil in real time, providing the system with continuous and real-time magnetic field information, which helps to achieve precise control.

[0028] (3) The control system of the present invention can output an analog voltage signal corresponding to the size of the three-dimensional magnetic field generated by the feedback coil, and can accurately adjust the output according to the change of the magnetic field to achieve precise control of the magnetic field.

[0029] (4) The present invention provides an active-passive composite magnetic shielding method, which uses a magnetic shielding barrel to shield the high-frequency interference magnetic field, and then uses a magnetic sensor to measure the size of the magnetic field in the uniform area of ​​the feedback coil in real time, and actively feeds back to the feedback coil through a control component, and adjusts the size of the magnetic field generated by the coil in real time. It can achieve three-dimensional adaptive shielding of the low-frequency interference magnetic field, thereby improving the performance of the magnetic shielding system. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a block diagram of the electrical connection structure of the active and passive composite magnetic shielding device;

[0031] Figure 2 It is a structural diagram of the active and passive composite magnetic shielding device;

[0032] Among them, 1-magnetic sensor, 2-magnetic shielding tube, 3-feedback coil, 4-control component, 5-bracket. DETAILED DESCRIPTION

[0033] The present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0034] Embodiment 1:

[0035] This embodiment provides an active-passive composite magnetic shielding device. Figure 1 and 2 , including an active shielding component and a magnetic shielding cylinder 2;

[0036] The active shielding component includes a powered feedback coil 3, which is used to generate a three-dimensional magnetic field that is equal to the three components of the low-frequency interference magnetic field and opposite in direction to offset the low-frequency interference magnetic field;

[0037] The magnetic shielding tube 2 is arranged inside the feedback coil 3 and is located in the magnetic field uniformity area of ​​the feedback coil 3, and is used for shielding high-frequency interference magnetic field.

[0038] This embodiment provides an active-passive composite magnetic shielding device, in which the magnetic shielding tube 2 is arranged in the uniform area of ​​the feedback coil 3. On the one hand, the size of the feedback coil 3 does not need to be limited by the space of the magnetic shielding tube 2, which is convenient for realizing active magnetic shielding in three-dimensional space; on the other hand, the uniform area of ​​the feedback coil 3 can cover the entire magnetic shielding tube 2. Compared with the previous method of built-in coils, the composite uniform area is larger, which is convenient for calibration of the equipment under test.

[0039] In one embodiment, the active shielding component further includes a magnetic sensor 1 and a control component 4; the control component 4 is electrically connected to the magnetic sensor 1 and the feedback coil 3 respectively;

[0040] The magnetic sensor 1 is located in the uniform area of ​​the feedback coil 3, and is used to obtain the three-dimensional magnetic field size data in the uniform area of ​​the feedback coil 3 in real time, and transmit the magnetic field size data to the control component 4; the control component 4 can output a corresponding analog current to the feedback coil 3 according to the three-dimensional magnetic field size data, so that the feedback coil 3 generates a corresponding offset three-dimensional magnetic field, so that the magnetic field in the uniform area remains constant;

[0041] Further, the control component 4 includes a control system and a voltage processing module;

[0042] The control system calculates and offsets the interfering magnetic field and outputs the corresponding analog voltage;

[0043] The voltage processing module is electrically connected between the feedback coil 3 and the control system. The voltage processing module is used to amplify the analog voltage and convert it into a corresponding analog current and supply power to the feedback coil 3 .

[0044] In one embodiment, the magnetic sensor 1 is a fluxgate sensor and is located outside the magnetic shielding tube 2 .

[0045] In one embodiment, the feedback coil 3 is composed of a three-axis coil frame and a three-axis winding; the feedback coil 3 is composed of one or more of a Helmholtz coil, a Buckel coil, a Brownberg coil, a Gartler coil, a Maxwell coil and a pitch-free coil.

[0046] In one embodiment, the magnetic shielding cylinder 2 is disposed in the uniform area of ​​the feedback coil 3 through the bracket 5 , and the center of the magnetic shielding cylinder 2 coincides with the center of the feedback coil 3 .

[0047] Embodiment 2:

[0048] Based on Example 1, this embodiment provides an active-passive composite magnetic shielding method, and the method is as follows:

[0049] The magnetic shielding tube 2 is arranged inside the feedback coil 3 and is located in the magnetic field uniformity area of ​​the feedback coil 3 to passively shield the high-frequency interference magnetic field;

[0050] The magnetic sensor 1 obtains the three-dimensional magnetic field size data in the uniform area of ​​the feedback coil 3 in real time and transmits it to the control component 4. The control system of the control component 4 receives the three-dimensional magnetic field size data and calculates and outputs the corresponding analog voltage according to the three-dimensional magnetic field size data;

[0051] The voltage processing module of the control component 4 converts the analog voltage into a corresponding analog current and provides it to the feedback coil 3;

[0052] The feedback coil 3 generates in real time a cancelling interference magnetic field that is equal in magnitude to the three components of the low-frequency interference magnetic field and opposite in direction, and actively cancels out the low-frequency interference magnetic field.

[0053] In summary, the above are only preferred embodiments of the present invention and are not intended to limit the protection scope of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. An active-passive composite magnetic shielding device, characterized in that: include: Active shielding components and magnetic shielding cylinders; The active shielding assembly includes a powered feedback coil, the feedback coil is used to generate a three-dimensional magnetic field that is equal in magnitude and opposite in direction to the three components of the low-frequency interference magnetic field, so as to offset the low-frequency interference magnetic field; The magnetic shielding tube is arranged in the feedback coil and is located in the magnetic field uniformity area of ​​the feedback coil, and is used for shielding high-frequency interference magnetic field.

2. An active-passive composite magnetic shielding device as claimed in claim 1, characterized in that: The active shielding component also includes a magnetic sensor and a control component; the control component is electrically connected to the magnetic sensor and the feedback coil respectively; The magnetic sensor is located in the uniform area of ​​the feedback coil, and is used to obtain the three-dimensional magnetic field size data in the uniform area of ​​the feedback coil in real time, and transmit the magnetic field size data to the control component; The control component can output a corresponding analog current to the feedback coil according to the three-dimensional magnetic field size data, so that the feedback coil generates a corresponding offset three-dimensional magnetic field.

3. An active-passive composite magnetic shielding device as claimed in claim 2, characterized in that: The control component includes a control system and a voltage processing module; The control system calculates and offsets the interfering magnetic field and outputs the corresponding analog voltage; The voltage processing module is electrically connected between the feedback coil and the control system. The voltage processing module is used to amplify the analog voltage and convert it into a corresponding analog current and supply power to the feedback coil.

4. An active-passive composite magnetic shielding device according to any one of claims 1 to 3, characterized in that: The feedback coil is composed of a three-axis coil frame and a three-axis winding; The feedback coil is composed of one or more of a Helmholtz coil, a Buckel coil, a Brownberg coil, a Gartler coil, a Maxwell coil and a pitchless coil.

5. An active-passive composite magnetic shielding method, based on the active-passive composite magnetic shielding device of claim 3, characterized in that: Here’s how: The magnetic shielding tube is arranged inside the feedback coil and is located in the magnetic field uniformity area of ​​the feedback coil to passively shield the high-frequency interference magnetic field; The magnetic sensor obtains the three-dimensional magnetic field size data in the uniform area of ​​the feedback coil in real time and transmits it to the control component. The control system of the control component receives the three-dimensional magnetic field size data and calculates and outputs the corresponding analog voltage according to the three-dimensional magnetic field size data. The voltage processing module of the control component amplifies the analog voltage and converts it into a corresponding analog current to provide to the feedback coil; The feedback coil generates in real time a cancelling interference magnetic field that is equal in magnitude to the three components of the low-frequency interference magnetic field and opposite in direction, thereby actively cancelling out the low-frequency interference magnetic field.

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