Non-contact current measurement method and device based on atom magnetometer

Abstract

The invention discloses a non-contact current measurement method and device based on an atom magnetometer, and relates to the technical field of quantum precision measurement and electric power metrology, and the method specifically comprises the steps: S1, enabling a measured cable to be connected into a current measurement device for fixation, and maintaining the distance between the atom magnetometer and the cable to be fixed in a measurement process; s2, starting an atom magnetometer to calibrate the current measuring device to obtain a conversion coefficient k of the current in the cable and the corresponding magnetic field, and the unit is nT / mA; s3, a current measuring device collects a magnetic field signal output by the atom magnetometer in real time and inputs the magnetic field signal into computer equipment, and a computer processing program extracts a magnetic field signal generated by cable current; s4, converting the magnetic field signal acquired by the atom magnetometer into a current signal according to the conversion coefficient k in the S2; and S5, outputting a current signal in real time by a computer processing program, and completing the measurement of the current in the cable. The method realizes non-contact measurement, and has the advantages of high precision, good real-time performance, simple hardware structure and the like.

Description

Technical Field

[0001] The invention relates to the technical field of quantum precision measurement and electric power metering, and in particular to a contactless current measurement method and device based on an atomic magnetometer. Background Art

[0002] With the development of power systems, current measurement in cables is particularly important, and power metering equipment is widely used in industrial and civil fields. High-precision metering systems place higher demands on power metering equipment, and traditional measurement methods based on the principle of mutual inductors are subject to the limitations of measurement hardware.

[0003] Therefore, it is necessary to provide a contactless current measurement method and device based on an atomic magnetometer to solve the above problems. Summary of the invention

[0004] The purpose of the present invention is to provide a contactless current measurement method and device based on an atomic magnetometer, which uses the atomic magnetometer to measure the changes in the magnetic field generated by the current in the cable, and then inversely performs the changes in the current. It has high sensitivity and resolution and can be applied to current measurement in the fields of power metering systems, current source generators, etc.

[0005] To achieve the above object, the present invention provides a contactless current measurement method based on an atomic magnetometer, which uses an atomic magnetometer in a magnetic shielding unit to measure the magnetic field generated by the current in the cable, calibrates the conversion coefficient between the current in the cable and the corresponding magnetic field, calculates the current signal and current amplitude change in the cable, and completes the measurement of the current in the cable, which specifically includes the following steps:

[0006] S1: Connect the measured cable to the current measuring device and fix it. During the measurement process, keep the distance between the atomic magnetometer and the cable fixed.

[0007] S2: Turn on the atomic magnetometer to calibrate the current measuring device to obtain the conversion coefficient k between the current in the cable and the corresponding magnetic field, in units of nT / mA;

[0008] S3: The current measuring device collects the magnetic field signal output by the atomic magnetometer in real time and inputs it into the computer device. The computer processing program extracts the magnetic field signal generated by the cable current;

[0009] S4: converting the magnetic field signal obtained by the atomic magnetometer into a current signal according to the conversion coefficient k in S2;

[0010] S5: The computer processing program outputs the current signal in real time to complete the measurement of the current in the cable.

[0011] Preferably, in step S2, the following steps are specifically included:

[0012] S21: Turn on the power supply of the atomic magnetometer, tune the frequency of the laser to the resonance frequency of the alkali metal atoms, and return the output signal of the magnetometer to zero;

[0013] S22: Standard currents with the same frequency and different amplitudes are passed through the cable to calibrate the measuring device;

[0014] S23: Record the response of the atomic magnetometer to currents of different amplitudes and calculate the standard conversion coefficient k between the current in the cable and the corresponding magnetic field.

[0015] Preferably, in step S4, the magnetic field B is calculated as follows:

[0016]

[0017] B=kI(2)

[0018] Where I represents the source current in the cable, L represents the integral path of the cable segment to be tested, dl represents the tiny line element of the source current, and e r is a unit vector, the direction of the vector is from the current element to the point to be measured, μ0 represents the vacuum magnetic permeability, r represents the distance from the wire to the atomic magnetometer gas chamber, and k is the conversion coefficient;

[0019] According to formula (1), for fixed distances r and L, the current and magnetic field are linearly related, and the linear conversion coefficient is expressed as k. According to formula (2), the change of the current I in the cable is known from the change of the magnetic field B generated by the cable current.

[0020] A device for a contactless current measurement method based on an atomic magnetometer comprises a magnetic shielding unit, a cable fixing device, an atomic magnetometer magnetic field measurement unit and computer equipment, wherein the magnetic shielding unit comprises a magnetic shielding barrel and a magnetic shielding barrel support arranged below the magnetic shielding barrel, both ends of the cable fixing device pass through the magnetic shielding barrel and are arranged on the outside of the magnetic shielding barrel, the atomic magnetometer magnetic field measurement unit comprises an atomic magnetometer and a supporting structure arranged below the atomic magnetometer, the supporting structure is arranged in the magnetic shielding barrel, and the output signal of the atomic magnetometer is connected to the computer equipment through a data transmission line.

[0021] Preferably, the cable fixing device comprises a hollow straight tube and two hexagon socket screws, and the cable to be tested passes through the hollow straight tube and is fixed by the two hexagon socket screws.

[0022] Preferably, a magnetic shielding barrel cover is provided on one side of the magnetic shielding barrel, a through hole is provided on the side of the magnetic shielding barrel, the cable fixing device passes through the through hole and is fixed to the magnetic shielding barrel, and a notch is provided on the magnetic shielding barrel cover for the data transmission line to pass through.

[0023] Therefore, the present invention adopts the above-mentioned non-contact current measurement method and device based on atomic magnetometer, which has the following beneficial effects:

[0024] (1) The present invention has higher current measurement accuracy and sensitivity.

[0025] (2) The present invention utilizes the advantages of the atomic magnetometer such as miniaturization and simple structure, measures the magnetic field generated by the cable current, and then inverts the change of the current to achieve non-contact real-time measurement. The system structure is simple and the cost is low.

[0026] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a flow chart of a contactless current measurement method based on an atomic magnetometer of the present invention;

[0028] Figure 2 It is an overall three-dimensional schematic diagram of a contactless current measuring device based on an atomic magnetometer of the present invention;

[0029] Figure 3 It is a schematic diagram of the internal structure of a contactless current measuring device based on an atomic magnetometer of the present invention;

[0030] Figure 4 It is a magnetic field signal diagram generated by the cable current collected by the atomic magnetometer in the present invention;

[0031] Figure 5 The current signal diagram in the cable is obtained by inversion in the present invention;

[0032] Figure 6 It is a signal diagram of the current amplitude changing with time obtained by the computer processing program in the present invention.

[0033] illustrate

[0034] 1. Cable to be tested; 2. Magnetic shielding barrel cover; 3. Magnetic shielding barrel support; 4. Computer equipment; 5. Data transmission line; 6. Magnetic shielding barrel; 7. Atomic magnetometer; 8. Support structure; 9. Cable fixing device. DETAILED DESCRIPTION

[0035] The technical solution of the present invention is further described below through the accompanying drawings and embodiments.

[0036] Unless otherwise defined, technical or scientific terms used in the present invention shall have the common meanings understood by one having ordinary skills in the field to which the present invention belongs.

[0037] The words "include" or "comprises" and the like used in the present invention mean that the elements before the word include the elements listed after the word, and do not exclude the possibility of also including other elements. The orientation or position relationship indicated by the terms "inside", "outside", "upper", "lower", etc. is based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation of the present invention. When the absolute position of the described object changes, the relative position relationship may also change accordingly. In the present invention, unless otherwise clearly specified and limited, the terms "attachment" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral body; it can be directly connected, or indirectly connected through an intermediate medium, and it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0038] like Figure 1 As shown, the present invention provides a contactless current measurement method based on an atomic magnetometer, which uses an atomic magnetometer in a magnetic shielding unit to measure the magnetic field generated by the current in the cable, calibrates the conversion coefficient between the current in the cable and the corresponding magnetic field, calculates the current signal in the cable and the current amplitude change, and completes the measurement of the current in the cable, which specifically includes the following steps:

[0039] S1: Connect the measured cable to the current measuring device and fix it. During the measurement process, keep the distance between the atomic magnetometer and the cable fixed.

[0040] S2: Turn on the atomic magnetometer to calibrate the current measuring device to obtain the conversion coefficient k between the current in the cable and the corresponding magnetic field, in units of nT / mA; in step S2, the following steps are specifically included:

[0041] S21: Turn on the power supply of the atomic magnetometer, tune the frequency of the laser to the resonance frequency of the alkali metal atoms, and return the output signal of the magnetometer to zero;

[0042] S22: Standard currents with the same frequency and different amplitudes are passed through the cable to calibrate the measuring device;

[0043] S23: Record the response of the atomic magnetometer to currents of different amplitudes and calculate the standard conversion coefficient k between the current in the cable and the corresponding magnetic field.

[0044] S3: The current measuring device collects the magnetic field signal output by the atomic magnetometer in real time and inputs it into the computer device. The computer processing program extracts the magnetic field signal generated by the cable current;

[0045] S4: According to the conversion coefficient k in S2, the magnetic field signal obtained by the atomic magnetometer is converted into a current signal; in step S4, the magnetic field B is calculated as follows:

[0046]

[0047] B=kI(2)

[0048] Where I represents the source current in the cable, L represents the integral path of the cable segment to be tested, dl represents the tiny line element of the source current, and e r is a unit vector, the direction of the vector is from the current element to the point to be measured, μ0 represents the vacuum magnetic permeability, r represents the distance from the wire to the atomic magnetometer gas chamber, and k is the conversion coefficient;

[0049] According to formula (1), for fixed distances r and L, the current and magnetic field are linearly related, and the linear conversion coefficient is expressed as k. According to formula (2), the change of the current I in the cable is known from the change of the magnetic field B generated by the cable current.

[0050] S5: The computer processing program outputs the current signal in real time to complete the measurement of the current in the cable.

[0051] like Figure 2 and Figure 3 As shown, a device for a contactless current measurement method based on an atomic magnetometer includes a magnetic shielding unit, a cable fixing device, an atomic magnetometer magnetic field measurement unit and a computer device. The magnetic shielding unit includes a magnetic shielding barrel 6 and a magnetic shielding barrel support 3 arranged below the magnetic shielding barrel. Both ends of the cable fixing device 9 pass through the magnetic shielding barrel 6 and are arranged on the outside of the magnetic shielding barrel 6. The atomic magnetometer magnetic field measurement unit includes an atomic magnetometer 7 and a support structure 8 arranged below the atomic magnetometer. The support structure 8 is arranged in the magnetic shielding barrel 6. The output signal of the atomic magnetometer 7 is connected to the computer device 4 through a data transmission line 5. The computer device 4 collects the output signal of the magnetometer in real time, and processes and calculates the current in the cable in real time through a program. A magnetic shielding barrel cover 2 is arranged on one side of the magnetic shielding barrel 6, and a through hole is arranged on the side of the magnetic shielding barrel 6. The cable fixing device 9 passes through the through hole and is fixed to the magnetic shielding barrel 6. A notch for the data transmission line 5 to pass through is arranged on the magnetic shielding barrel cover 2.

[0052] The cable fixing device 9 includes a hollow straight tube and two hexagon socket screws. The cable 1 to be tested passes through the hollow straight tube and is fixed by the two hexagon socket screws, so as to fix the distance between the cable to be tested 1 and the atomic magnetometer 7 in the sensitive direction.

[0053] Example

[0054] A current with an amplitude of 1 mA and a frequency of 26.5 Hz is passed through the cable, and the sampling rate of the atomic magnetometer is set to 1000 Hz. The atomic magnetometer 7 is sensitive to the predicted magnetic field changes around the cable 1 and measures the magnetic field amplitude, such as Figure 4 As shown in the figure, the magnetic field signal generated by the cable current is obtained, and the processing program in the computer device 4 calculates the current change signal in the cable according to the standard conversion coefficient of the pre-calibrated current and the corresponding magnetic field, such as Figure 5 Finally, the processing program of the computer device 4 extracts the current amplitude signal that changes with time, such as Figure 6 As shown, this embodiment uses the FFT (Fast Fourier Transform) method to extract the current amplitude, uses a 4s time period for FFT processing, and slides and selects data at a time interval of 0.5s, thereby realizing real-time FFT processing and extracting the AC current amplitude.

[0055] Therefore, the present invention adopts the above-mentioned contactless current measurement method and device based on atomic magnetometer, uses atomic magnetometer in the magnetic shielding unit to measure the magnetic field generated by the current in the cable, and calculates the current signal and current amplitude change in the cable through the conversion coefficient of the pre-calibrated current in the cable and the corresponding magnetic field, thereby completing the measurement of the current in the cable.

[0056] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A contactless current measurement method based on an atomic magnetometer, characterized in that: An atomic magnetometer is used in the magnetic shielding unit to measure the magnetic field generated by the current in the cable, the conversion coefficient between the current in the cable and the corresponding magnetic field is calibrated, the current signal and the current amplitude change in the cable are calculated, and the current measurement in the cable is completed, which specifically includes the following steps: S1: Connect the measured cable to the current measuring device and fix it. During the measurement process, keep the distance between the atomic magnetometer and the cable fixed. S2: Turn on the atomic magnetometer to calibrate the current measuring device to obtain the conversion coefficient k between the current in the cable and the corresponding magnetic field, in units of nT / mA; S3: The current measuring device collects the magnetic field signal output by the atomic magnetometer in real time and inputs it into the computer device. The computer processing program extracts the magnetic field signal generated by the cable current; S4: converting the magnetic field signal obtained by the atomic magnetometer into a current signal according to the conversion coefficient k in S2; S5: The computer processing program outputs the current signal in real time to complete the measurement of the current in the cable.

2. A contactless current measurement method based on an atomic magnetometer according to claim 1, characterized in that: In step S2, the following steps are specifically included: S21: Turn on the power supply of the atomic magnetometer, tune the frequency of the laser to the resonance frequency of the alkali metal atoms, and return the output signal of the magnetometer to zero; S22: Standard currents with the same frequency and different amplitudes are passed through the cable to calibrate the measuring device; S23: Record the response of the atomic magnetometer to currents of different amplitudes and calculate the standard conversion coefficient k between the current in the cable and the corresponding magnetic field.

3. The contactless current measurement method based on an atomic magnetometer according to claim 1, characterized in that: In step S4, the magnetic field B is calculated as follows: B=kI (2) Where I represents the source current in the cable, L represents the integral path of the cable segment to be tested, dl represents the tiny line element of the source current, and e r is a unit vector, the direction of the vector is from the current element to the point to be measured, μ0 represents the vacuum magnetic permeability, r represents the distance from the wire to the atomic magnetometer gas chamber, and k is the conversion coefficient; According to formula (1), for fixed distances r and L, the current and magnetic field are linearly related, and the linear conversion coefficient is expressed as k. According to formula (2), the change of the current I in the cable is known from the change of the magnetic field B generated by the cable current.

4. A device for contactless current measurement based on an atomic magnetometer according to any one of claims 1 to 3, characterized in that: The invention comprises a magnetic shielding unit, a cable fixing device, an atomic magnetometer magnetic field measuring unit and computer equipment. The magnetic shielding unit comprises a magnetic shielding barrel and a magnetic shielding barrel support arranged below the magnetic shielding barrel. Both ends of the cable fixing device pass through the magnetic shielding barrel and are arranged on the outside of the magnetic shielding barrel. The atomic magnetometer magnetic field measuring unit comprises an atomic magnetometer and a supporting structure arranged below the atomic magnetometer. The supporting structure is arranged in the magnetic shielding barrel. The output signal of the atomic magnetometer is connected to the computer equipment through a data transmission line.

5. A contactless current measuring device based on an atomic magnetometer according to claim 4, characterized in that: The cable fixing device comprises a hollow straight tube and two hexagon socket screws. The cable to be tested passes through the hollow straight tube and is fixed by the two hexagon socket screws.

6. A contactless current measuring device based on an atomic magnetometer according to claim 4, characterized in that: A magnetic shielding barrel cover is provided on one side of the magnetic shielding barrel, a through hole is provided on the side of the magnetic shielding barrel, the cable fixing device passes through the through hole and is fixed to the magnetic shielding barrel, and a notch is provided on the magnetic shielding barrel cover for the data transmission line to pass through.

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