KR20230101637A - Cryogenic hall sensor array for diagnosing high temperature superconductor coil - Google Patents

Abstract

Disclosed is a cryogenic hall sensor array for diagnosing high-temperature superconducting coils.
A cryogenic hall sensor array for diagnosing high-temperature superconducting coils according to an example includes two or more hall sensor array units, each of the hall sensor array units including a hall sensor unit having a plurality of single hall sensors disposed at equal intervals, Two or more hall sensor array units are spaced apart from each other to have the same offset in the longitudinal direction of the hall sensor unit between adjacent hall sensor array units.
If the present invention is used, it is possible to simultaneously measure the time-varying magnetic field change due to the shielding current generated in the high-temperature superconducting coil at several points by providing a small spatial resolution by using the Hall sensor arrangement with very small intervals and the diagonal arrangement of the array. There is an effect of realizing a cryogenic hall sensor array for diagnosing superconducting coils.

Description

Cryogenic hall sensor array for diagnosis of high temperature superconducting coil {CRYOGENIC HALL SENSOR ARRAY FOR DIAGNOSING HIGH TEMPERATURE SUPERCONDUCTOR COIL}

The present invention relates to a cryogenic Hall sensor array for diagnosing high-temperature superconducting coils.

A superconductor means a material whose DC electrical resistance becomes zero in a cryogenic environment, and a superconductor for manufacturing an electromagnet has the main characteristic parameters of 1) critical magnetic field, 2) critical temperature, and 3) critical current density that maintain a superconducting state. do.

Among them, superconductors having a critical temperature of about 30 K or more are classified as high-temperature superconductors, and REBCO (Rare Earth Barium Copper Oxide) series high-temperature superconducting wires are mainly applied to manufacture magnets for generating high magnetic fields.

The high-temperature superconductor has a higher critical magnetic field than the low-temperature superconductor, and the high-temperature superconducting coil using the non-insulated winding method has high current density and operational stability.

High-temperature superconducting coils are applied to NMR (Nuclear Magnetic Resonance Imaging) and MRI (Magnetic Resonance Imaging), which are essential for biology, chemistry, and medicine, and are also necessary for realizing nuclear fusion devices for next-generation energy generation.

There are 82 companies with superconducting magnet technology worldwide, and as fields requiring high magnetic fields increase, the superconducting market, which was worth 5.5 billion dollars in 2016 (approximately 6.5 trillion won), will grow to 8.7 billion in 2022. It is expected to increase by USD (approximately 10.3 trillion won), and is expected to grow at an average annual rate of 7.5%.

Coils made using these high-temperature superconducting wires generate a higher magnetic field than low-temperature superconducting coils, but due to the screening current (shielding current), they generate a non-uniform magnetic field that varies with time, contrary to the designed magnetic field distribution.

In order to compensate for such a non-uniform and time-varying magnetic field, it is necessary to measure the magnitude of the magnetic field at several points at the same time. However, in general prior art and attempts, the magnitude of the magnetic field according to the position was measured using a magnetic field mapping device, but by using an XYZ axis motor Since it was measured while moving, it was not enough to infer the distribution of the magnetic field by the time-varying shielding current.

Conventional hall sensor arrays or magnetic image processing tiles do not guarantee normal operation in a cryogenic environment, and there is a problem that deformation due to thermal contraction and expansion due to rapid temperature change occurs or malfunction due to liquefaction of water vapor on the sensor surface. .

The present invention has been proposed to compensate for the disadvantages of the prior art, and an object of the present invention is to provide a cryogenic hall sensor array for diagnosing a high-temperature superconducting coil for evaluating the magnetic field characteristics of the high-temperature superconducting coil and measuring the shielding current in space-time.

In addition, in the performance evaluation before attaching the high-temperature superconducting coil to the magnet system, the present invention can measure the magnetic field stability over time and the magnetic field stability over space through one PCB, and can be used without failure even in a cryogenic environment. Another object is to provide a cryogenic Hall sensor array for diagnosing high-temperature superconducting coils.

A cryogenic hall sensor array for diagnosing high-temperature superconducting coils according to an example includes two or more hall sensor array units, each of the hall sensor array units including a hall sensor unit having a plurality of single hall sensors disposed at equal intervals, Two or more hall sensor array units are spaced apart from each other to have the same offset in the longitudinal direction of the hall sensor unit between adjacent hall sensor array units.

At this time, the spatial resolution of the Hall sensor array unit is preferably a value obtained by adding the width of the single Hall sensor to the distance between the center portions of two adjacent single Hall sensors.

Also, the number of Hall sensor array units is preferably a natural number that divides the spatial resolution of the single Hall sensor.

Preferably, the spatial resolution of the Hall sensor array is a value obtained by dividing the spatial resolution of the single Hall sensor of the Hall sensor array unit by the number of Hall sensor array units.

Preferably, the offset is a value obtained by dividing the spatial resolution of the single Hall sensor of the Hall sensor array unit by the number of Hall sensor array units.

Using the present invention, it is possible to simultaneously measure the time-varying magnetic field change due to the shielding current generated in a high-temperature superconducting coil at several points by providing a small spatial resolution by using a Hall sensor arrangement with a very small interval and an oblique arrangement of the array. There is an effect of realizing a cryogenic hall sensor array for diagnosing superconducting coils.

1 is a view showing a hall sensor array unit included in a cryogenic hall sensor array for diagnosing a high-temperature superconducting coil according to an example of the present invention;
2 is a simplified view of the hall sensor array unit of FIG. 1;
3 is a diagram illustrating a hall sensor array formed by combining a plurality of hall sensor array units of FIG. 1;
4 is a graph showing voltage distributions of Hall sensors measured when permanent magnets are discontinuously moved on the surface of a Hall sensor array PCB in a room temperature environment;
5 is a graph showing voltage distributions of Hall sensors measured when permanent magnets are continuously moved on the surface of a Hall sensor array PCB in a cryogenic environment;
6 is a view showing an embodiment in which a cryogenic Hall sensor array unit for diagnosing a high-temperature superconducting coil is attached to the surface of a wound high-temperature superconducting coil.

1 is a view showing a hall sensor array unit included in a cryogenic hall sensor array for diagnosing a high-temperature superconducting coil according to an example of the present invention.

A cryogenic hall sensor array for diagnosing high-temperature superconducting coils includes a plurality of hall sensor array units disposed offset from each other with a predetermined offset.

As shown in FIG. 1 , the hall sensor array unit 10 included in the cryogenic hall sensor array for diagnosing high-temperature superconducting coils further includes a hall sensor unit 100, an input terminal unit 110, and an output terminal unit 120.

In the Hall sensor unit 100, a plurality of single Hall sensors 102 are arranged at regular intervals.

A plurality of single input terminals 112 for individually supplying power to the plurality of single hall sensors 102 are disposed in the input terminal unit 110 .

A plurality of single output terminals 122 for individually supplying power to the plurality of single hall sensors 102 are disposed in the output terminal unit 120 .

In general, the hall sensor array unit 10 can be implemented by mounting elements on a printed circuit board (PCB).

FIG. 2 is a simplified view of the hall sensor array unit of FIG. 1 .

Spatial resolution may be defined as an interval in space of a magnetic field to be measured. In this specification, it can also be considered as a central interval between single Hall sensors.

When the spatial resolution of the hall sensor array unit 10 is R (unit), a formula for calculating the spatial resolution of the hall sensor array unit 10 can be expressed as Equation 1 below.

[Equation 1]

R(unit) = d + w

= { l - ( w × n )}/ n + w

= l/n.

( At this time, hall sensor spacing (d), width excluding left and right margins of PCB array (l), hall sensor width (w))

FIG. 3 is a diagram illustrating a cryogenic hall sensor array for diagnosing a high-temperature superconducting coil formed by combining a plurality of hall sensor array units of FIG. 1 .

As shown in FIG. 3 , the cryogenic hall sensor array for diagnosing high-temperature superconducting coil includes a plurality of hall sensor array units disposed offset from each other with a predetermined offset.

In the embodiment of FIG. 3 , a case in which the cryogenic hall sensor array 1 for diagnosing a high-temperature superconducting coil includes three Hall sensor array units arranged offset by an offset t is illustrated.

Meanwhile, in this embodiment, it is assumed that the spatial resolution ((R(unit)) of the hall sensor array unit is 2.7 mm.

Since the number of hall sensor array units ( N ) needs to be a natural number that divides 2.7 mm, which is the spatial resolution (R (unit)) of the hall sensor array unit, N=3 is appropriate.

In this case, as shown in Equation 2, the spatial resolution (R(array)) of the cryogenic hall sensor array 1 for diagnosing the high-temperature superconducting coil is the spatial resolution (R(unit)) of the hall sensor array unit. It is a value divided by the number of units ( N ). in other words,

[Equation 2]

R(array) = Resolution(unit) / N

= 2.7(mm) / 3

= 0.9 (mm).

In addition, as shown in Equation 3, the offset ( t ) between the hall sensor array units of the cryogenic hall sensor array 1 for diagnosing the high-temperature superconducting coil is the spatial resolution (R (unit)) of the hall sensor array unit It is a value divided by the number of array units ( N ). in other words,

[Equation 3]

t = ( d + w ) / N

= R(unit) / N.

= 2.7(mm) / 3

= 0.9 (mm).

This can be easily understood by referring to FIG. 3 .

That is, if the hall sensor array units 10A, 10B, and 10C are arranged offset to have the same offset, the hall sensor array 1 is equally spaced within each hall sensor array unit 10A, 10B, and 10C. It is possible to obtain substantially the same effect as a new Hall sensor array unit having more densely arranged Hall sensor units so that the distance ( d+w ) between the single Hall sensors arranged as 1/N is reduced.

4 is a graph showing voltage distributions of Hall sensors measured when permanent magnets are discontinuously moved on the surface of a Hall sensor array PCB in a room temperature environment.

The hall sensor array was tested for linearity according to the magnitude of the magnetic field and stability in the cryogenic environment by using a permanent magnet in which the magnitude of the magnetic field does not change with time in a room temperature environment (296 K) and a cryogenic environment (77 K).

The linearity according to the size of the magnetic field was observed using two permanent magnets with different magnetic field strengths, and the stability of the sensor in the cryogenic environment was tested through measurements in the room temperature -> cryogenic temperature -> room temperature environment.

The voltage distribution of Hall sensors (No. 1: leftmost, No. 10: rightmost) measured when a permanent magnet is discontinuously moved on the surface of a Hall sensor array PCB in a room temperature environment (296 K) is shown. The DC current applied to the Hall sensor array was 1 mA, and the magnitude of the magnetic field of the permanent magnet measured using a precision Hall sensor sensor calibrated for temperature and magnetic field was 2.08 mV.

5 is a graph showing voltage distributions of Hall sensors measured when a permanent magnet is continuously moved on the surface of a Hall sensor array PCB in a cryogenic environment.

Voltage distribution of Hall sensors (No. 1: leftmost, No. 10: rightmost) measured when a permanent magnet was continuously moved on the surface of a Hall sensor array PCB in a cryogenic environment (77 K). The DC current applied to the Hall sensor array was 1 mA, and the magnitude of the magnetic field of the permanent magnet measured using a precision Hall sensor sensor calibrated for temperature and magnetic field was 3.41 mV.

6 is a view showing an embodiment in which a cryogenic Hall sensor array unit for diagnosing a high-temperature superconducting coil is attached to the surface of a wound high-temperature superconducting coil.

The hall sensor array unit and/or the hall sensor array may be used by attaching it to a surface of a wound high-temperature superconducting coil (gray).

The red solid arrow represents the operating current flowing through the high-temperature superconducting coil through the current source, and the blue dotted arrow represents the shielding current generated in the coil.

Unlike conventional hall sensors or hall sensor arrays that measure magnetic fields, the present invention has the following advantages.

(1) Stable magnetic field can be measured linearly even in a cryogenic environment (77 K, about -196 ℃).

(2) By mounting 10 Hall sensors on a small PCB of 30 mm x 9.1 mm, it can provide very small spatial resolution (2.7 mm) by itself.

(3) A smaller spatial resolution can be provided through the oblique offset arrangement.

(4) A time-varying magnetic field can be measured simultaneously for several points.

(5) Since it has a flat shape, it can be kept parallel to the surface of the high-temperature superconducting coil whose magnetic field is to be precisely measured.

(6) It is safe from rapid temperature change and foreign substance penetration through cryogenic epoxy finish.

As a result of tests using permanent magnets in room temperature (296 K) and cryogenic environments (77 K), the magnetic field signals measured in room temperature and cryogenic environments all showed excellent linearity and sensitivity. When tested in the environment, it was confirmed that the sensor did not fail or deform.

The present invention can be manufactured through a general PCB process, and the work of attaching a hall sensor with a small size of 1.2 mm x 0.5 mm can be mass-produced by applying a metal mask and Surface Mounter Technology.

The currently proposed Hall sensor array can be connected in series or arranged in an oblique line, but a flexible PCB design is required according to the spatial resolution of the magnetic field measurement required in various fields and the size of the allowed space.

It can be applied to electronic devices and systems that generate a magnetic field, and a typical example is a performance evaluation device for an electric motor operating through a magnetic field.

Meanwhile, the cryogenic hall sensor array for diagnosing the high-temperature superconducting coil according to the present invention may be impregnated with cryogenic epoxy.

In this case, since a kind of coating is performed through impregnation, it is possible to prevent sensor failure due to deformation by minimizing deformation of the PCB by ensuring magnetic field measurement in a cryogenic environment through removal of foreign substances and prevention of water vapor liquefaction and prevention of rapid temperature change. can

One . . . . . . offset hall sensor array
10. . . . . . hall sensor array unit
10A,10B,10C. . . . . . hall sensor array unit
100. . . . . . Hall sensor part
102. . . . . . single hall sensor
110. . . . . . input terminal part
112. . . . . . single input terminal
120. . . . . . output terminal part
122. . . . . . single output terminal

Claims (5)

Including two or more hall sensor array units,
Each of the hall sensor array units includes a hall sensor unit having a plurality of single hall sensors arranged at equal intervals,
Wherein the two or more hall sensor array units are spaced apart from each other to have an offset of the same size in the longitudinal direction of the hall sensor unit between adjacent hall sensor array units.
According to claim 1,
The spatial resolution of the Hall sensor array unit is a value obtained by adding the width of the single Hall sensor to the distance between the center portions of two adjacent single Hall sensors.
According to claim 2,
The cryogenic hall sensor array for diagnosing high-temperature superconducting coils, wherein the number of hall sensor array units is a natural number dividing the spatial resolution of the hall sensor array units.
According to claim 3,
The spatial resolution of the hall sensor array is a value obtained by dividing the spatial resolution of the hall sensor array unit by the number of the hall sensor array units.
According to claim 3,
The offset is a value obtained by dividing the spatial resolution of the Hall sensor array unit by the number of the Hall sensor array units.

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