Iron core magnetic field coil constant measuring device based on magnetic flux variable

Abstract

An iron core magnetic field coil constant measuring device based on a magnetic flux variable comprises a magnetic flux measuring coil, a data acquisition module, a sampling resistor and a signal source, and the device utilizes magnetic flux change generated at the moment when a magnetic field coil with an iron core is powered on / off, and then utilizes the magnetic flux measuring coil to measure the generated magnetic flux change. And obtaining the constant of the magnetic field coil with the iron core through calculation, thereby completing constant measurement of the magnetic field coil with the iron core. The device can effectively solve the problem that the coil constant of the magnetic field coil with the iron core cannot be measured, and the problem that the coil constant calculation error is large due to the fact that the magnetic conductivity of the iron core cannot be accurately measured is solved.

Description

Technical Field

[0001] The present invention relates to the field of magnetic metrology technology, and in particular to an "iron core" magnetic field coil constant measuring device based on magnetic flux variables, wherein the "iron core" generally refers to an inner core material with high magnetic permeability, not specifically "iron". Background Art

[0002] Magnetic field coils are key devices commonly used in the field of magnetic metrology to generate magnetic fields. Nowadays, with the advancement of technology, in order to solve the problem of in-situ calibration of fluxgate sensors (magnetometers), a new technology with a built-in calibration magnetic field coil has been developed, such as the attached Figure 1 As shown, this technology uses the enameled wire winding wound on the probe wire frame (or coaxial wire frame) in the fluxgate sensor (magnetometer) probe to establish a calibration coil. When a certain excitation current passes through the coil, a magnetic field is generated inside it. By observing whether the change in the sensor output magnetic field meets the expected magnetic field change range, the fluxgate sensor (magnetometer) is calibrated.

[0003] Because this magnetic field coil is tightly combined with the sensor probe, it can be regarded as a magnetic field coil with an iron core. The measurement methods used in the existing verification procedures and calibration specifications cannot solve this type of magnetic field coil. The existing methods mainly include the magnetic field vector method, the magnetic field scalar method, and the standard coil method. All of them require the standard magnetometer to be placed inside the magnetic field coil to be measured, and the magnetic field coil constant is calibrated by measuring the changes in magnetic induction intensity and the changes in excitation current. The common principles of existing calibration devices are shown in the attached figure. Figure 2 As shown. However, the existing measurement method cannot solve the calibration problem due to the mechanical structure of the magnetic field coil with an iron core. Summary of the invention

[0004] In order to solve the problem of accurately measuring the constant of an air-core magnetic field coil, the present disclosure provides a device for measuring the constant of a detection coil by utilizing magnetic flux changes, which utilizes the magnetic flux changes generated by a magnetic field coil with an iron core at the moment of power on / off, and then uses a magnetic flux measurement coil to measure the generated magnetic flux changes, and then obtains the constant of the magnetic field coil with an iron core by calculation, thereby solving the problem that the coil constant of the magnetic field coil with an iron core cannot be measured, and avoiding the problem of large errors in the calculation of the coil constant caused by the inability to accurately measure the magnetic permeability of the iron core.

[0005] The present disclosure provides a device for measuring the constant of a magnetic field coil with an iron core based on a magnetic flux variable, comprising: a signal source, a sampling resistor, a magnetic flux measurement coil, and a data acquisition module, wherein:

[0006] The signal source is used to output current to the magnetic field coil with an iron core through a sampling resistor;

[0007] A magnetic field coil with an iron core, used to provide a rapidly changing magnetic field signal to the flux measurement coil;

[0008] The magnetic flux measuring coil is sleeved outside the magnetic field coil with an iron core and is used to sense the change of the magnetic flux passing through the magnetic flux measuring coil to generate an induced electromotive force;

[0009] The data acquisition module is used to measure the induced electromotive force of the flux measurement coil, calculate the flux change ΔΦ; and obtain the driving current I flowing to the iron core magnetic field coil; and calculate the coil constant of the iron core magnetic field coil according to the flux change ΔΦ and the driving current I.

[0010] Furthermore, the types of signal sources include:

[0011] A pulse signal source is used to drive the magnetic field coil with an iron core to generate a step magnetic field signal;

[0012] DC regulated power supply, at this time, the iron core magnetic field coil is quickly pulled out from the center of the flux measurement coil in a powered state, providing a rapidly changing magnetic field signal to the flux measurement coil.

[0013] Furthermore, the magnetic flux measurement coil is used to achieve a signal output between 0.1mV and 1V.

[0014] Furthermore, the characteristics of the flux measurement coil include one or more of the following characteristics:

[0015] a) The homogeneous area is large enough to accommodate the object to be measured, and the volume of the 0.5% magnetic field homogeneous area is greater than 1 / 3 of the volume of the object to be measured;

[0016] b) The structure adopts Helmholtz coil structure;

[0017] c)50m 2 The equivalent turn area is about 20 to 25 turns;

[0018] d) The wire rack should be made of non-metallic, low-conductivity materials and should be chemically and physically stable at the expected working environment temperature;

[0019] e) A grounded copper comb-shaped covering is used outside the winding layer to reduce the effect of external electromagnetic interference coupling into the measuring coil during measurement.

[0020] Furthermore, the data acquisition module adopts a dual-channel data acquisition device, the AD bit number of which is selected to be above 18 bits, the sampling rate is above 10kHz, and the voltage pulse edge is matched.

[0021] Furthermore, the sampling resistor is composed of a non-inductive resistor with a resistance value between 1Ω and 10Ω.

[0022] Furthermore, the coil constant of the magnetic field coil with an iron core is calculated according to the following formula:

[0023] Assume that the measurement coil constant K of the pre-calibrated flux measurement coil is φ , that is, the measurement coil turn area NA; the driving current through the iron core magnetic field coil is I, and the magnetic flux change through the flux measurement coil is ΔΦ, then

[0024]

[0025] Where K B This is the coil constant of the magnetic field coil with an iron core.

[0026] Compared with the prior art, the beneficial effects of the present invention are: (1) compared with the prior art, it can solve the problem that the coil constant of the iron core magnetic field coil cannot be measured; (2) the measuring device adopts flux measurement to avoid the problem of large error in the calculation of the coil constant caused by the inability to accurately measure the magnetic permeability of the iron core; (3) the device composition is simple; (4) the measurement calculation process is convenient. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The above and other objects, features and advantages of the present disclosure will become more apparent through a more detailed description of exemplary embodiments of the present disclosure in conjunction with the accompanying drawings, wherein like reference numerals generally represent like components throughout the exemplary embodiments of the present disclosure.

[0028] Figure 1 It is a schematic diagram of the structure of a fluxgate sensor with a calibration magnetic field coil;

[0029] Figure 2 It is the principle of common magnetic field coil constant calibration device;

[0030] Figure 3 A schematic diagram of a system composition according to an exemplary embodiment of the present disclosure. DETAILED DESCRIPTION

[0031] The preferred embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the preferred embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to make the present disclosure more thorough and complete, and to fully convey the scope of the present disclosure to those skilled in the art.

[0032] The present disclosure provides a device for measuring the constant of an "iron core" magnetic field coil based on magnetic flux variables. The basic principle is described as follows:

[0033] This device uses the interaction between the magnetic flux measurement coil and the magnetic field coil with an iron core to achieve this, and the basic physical principle involved is Faraday's law of electromagnetic induction. Specifically, it includes:

[0034] a) According to Faraday's law of electromagnetic induction, when the magnetic flux in a closed coil changes, an induced electromotive force will be generated in the closed coil. Its magnitude is proportional to the rate of change of the magnetic flux, and the mathematical expression is:

[0035] ε=-dΦ / dt (1)

[0036] Among them, ε is the induced electromotive force and Φ is the magnetic flux passing through the measuring coil.

[0037] Based on equation (1), the induced voltage is integrated to obtain the change ΔΦ of the magnetic flux passing through the measuring coil.

[0038] b) The relationship between the magnetic flux Φ passing through the measuring coil and the magnetic field B therein and the measuring coil turn area NA is expressed as: Φ=B·NA·cosθ, where θ is the angle between the measuring coil plane and the magnetic field direction of the iron core magnetic field coil.

[0039] In an exemplary embodiment, the system structure is as shown in the attached Figure 3 As shown, it mainly includes: a flux measurement coil, a data collector, a sampling resistor, and a signal source.

[0040] 1) Design and manufacture of magnetic flux measurement coils to achieve signal output between 0.1mV and 1V.

[0041] The main design core requirements are: a) the coil size matches the volume of the object being measured; b) the coil shape is symmetrical; c) the number of coil turns balances the number of turns and the resistance; d) the coil material is sufficiently stable; e) the coil is electromagnetically compatible. That is:

[0042] a) The uniform area of ​​the magnetic flux measurement coil is sufficient to accommodate the object to be measured, and the volume of the 0.5% magnetic field uniform area is greater than 1 / 3 of the volume of the object to be measured;

[0043] b) The structure of the magnetic flux measurement coil usually adopts the Helmholtz coil structure, which is easy to pick up and position;

[0044] c) The flux measurement coil ensures sufficient turns to increase the induced electromotive force amplitude, while reducing the turns resistance to reduce thermal noise. The conventional design parameters are 50m 2 The equivalent turn area is about 20 to 25 turns;

[0045] d) The wire rack should be made of non-metallic, low-conductivity materials that are chemically and physically stable at the expected working environment temperature, such as polyoxymethylene;

[0046] e) Take measures such as grounding copper comb-shaped covering sheets outside the winding layer to reduce the influence of external electromagnetic interference coupling into the measuring coil during measurement.

[0047] 2) Select a suitable dual-channel data acquisition device in terms of AD bit number and sampling rate. The main technical requirements are: the AD bit number is accurate enough to identify the voltage signal change rate of 1μV, usually 18 bits or more; the sampling rate is above 10kHz, matching the voltage pulse edge.

[0048] 3) The sampling resistor is composed of non-inductive resistors, and the resistance value is selected between 1Ω and 10Ω.

[0049] 4) Signal source: When using the impact measurement method, you only need to configure a suitable pulse signal source; when using the pull-out measurement method, configure a conventional DC regulated power supply.

[0050] Using the above equipment, the specific measurement implementation process is as follows:

[0051] a) The iron core magnetic field coil generates a step magnetic field signal,

[0052] The impact measurement method can be used, that is, a pulse signal source is used to drive the magnetic field coil with an iron core to work;

[0053] The pull-out measurement method can also be used, in which the iron core magnetic field coil with direct current is quickly removed from the center of the flux measurement coil while it is energized.

[0054] b) The flux measurement coil senses the change in magnetic flux and outputs the induced voltage to the data acquisition device. The data acquisition device obtains the change ΔΦ of the magnetic flux passing through the flux measurement coil caused by the change in the magnetic field of the magnetic field coil with the iron core by measuring and integrating the induced voltage;

[0055] c) Based on the measurement coil constant K of the pre-calibrated flux measurement coil Φ (i.e. measuring the coil turn area NA), and the data logger obtains the driving current I (stable current provided by the signal source) through the iron core magnetic field coil by measuring the voltage across the sampling resistor, and calculates the coil constant of the iron core magnetic field coil. The formula is: K B =ΔΦ / (K Φ I), where K B is the coil constant of the field coil with iron core.

[0056] Therefore, this embodiment completes the measurement of the constant of the magnetic field coil with an iron core based on the change of magnetic flux.

[0057] The above technical scheme is only an exemplary embodiment of the present invention. For those skilled in the art, it is easy to make various types of improvements or modifications based on the application methods and principles disclosed in the present invention, and it is not limited to the method described in the above specific embodiment of the present invention. Therefore, the method described above is only preferred and does not have a restrictive meaning.

Claims

1. A device for measuring the constant of a magnetic field coil with an iron core based on a magnetic flux variable, characterized in that: include: Signal source, sampling resistor, magnetic flux measurement coil, data acquisition module, including: The signal source is used to output current to the magnetic field coil with an iron core through a sampling resistor; A magnetic field coil with an iron core, used to provide a rapidly changing magnetic field signal to the flux measurement coil; The magnetic flux measuring coil is sleeved outside the magnetic field coil with an iron core and is used to sense the change of the magnetic flux passing through the magnetic flux measuring coil to generate an induced electromotive force; The data acquisition module is used to measure the induced electromotive force of the flux measurement coil, calculate the flux change ΔΦ; and obtain the driving current I flowing to the iron core magnetic field coil; and calculate the coil constant of the iron core magnetic field coil according to the flux change ΔΦ and the driving current I.

2. The device according to claim 1, characterized in that The signal source adopts: A pulse signal source is used to drive the magnetic field coil with an iron core to generate a step magnetic field signal; Or a DC regulated power supply, at this time, the iron core magnetic field coil is quickly pulled out from the center of the flux measuring coil in a powered state, providing a rapidly changing magnetic field signal to the flux measuring coil.

3. The device according to claim 1 or 2, characterized in that: The magnetic flux measuring coil is used to achieve a signal output between 0.1mV and 1V.

4. The device according to claim 3, characterized in that The characteristics of the flux measurement coil include one or more of the following characteristics: a) The homogeneous area is large enough to accommodate the object to be measured, and the volume of the 0.5% magnetic field homogeneous area is greater than 1 / 3 of the volume of the object to be measured; b) The structure adopts Helmholtz coil structure; c)50m 2 The equivalent turn area is about 20 to 25 turns; d) The wire rack should be made of non-metallic, low-conductivity materials and should be chemically and physically stable at the expected working environment temperature; e) A grounded copper comb-shaped covering is used outside the winding layer to reduce the effect of external electromagnetic interference coupling into the measuring coil during measurement.

5. The device according to claim 1 or 2, characterized in that: The data acquisition module adopts a dual-channel data acquisition device, the AD bit number of which is selected to be above 18 bits, the sampling rate reaches above 10kHz, and the voltage pulse edge is matched.

6. The device according to claim 1 or 2, characterized in that: The sampling resistor is composed of a non-inductive resistor with a resistance value between 1Ω and 10Ω.

7. The device according to claim 1, characterized in that The coil constant of a field coil with an iron core is calculated according to the following formula: Assume that the measurement coil constant K of the pre-calibrated flux measurement coil is Φ , that is, the measurement coil turn area NA; the driving current through the iron core magnetic field coil is I, and the magnetic flux change through the flux measurement coil is ΔΦ, then Where K B This is the coil constant of the magnetic field coil with an iron core.

Images