A magnetic flux variable based constant measurement device for a core type magnetic field coil

Abstract

A kind of based on magnetic flux variable constant measurement device of magnetic field coil with core, comprising: magnetic flux measuring coil, data acquisition module, sampling resistance, signal source, the device utilizes the magnetic flux variation generated by magnetic field coil with core when energized / when not energized, then the magnetic flux variation generated is measured using magnetic flux measuring coil, then the constant of magnetic field coil with core is obtained by calculation, to complete the constant measurement of magnetic field coil with core. The device can effectively solve the problem that the constant of magnetic field coil with core cannot be measured, and then avoid the problem of large calculation error of constant caused by the fact that the magnetic permeability of core cannot be accurately measured.

Description

Technical Field

[0001] This invention relates to the field of magnetic measurement technology, and in particular to a device for measuring the constant of a magnetic field coil with an iron core based on magnetic flux variation. Here, "iron core" refers to a high-permeability core material, not specifically "iron". Background Technology

[0002] Magnetic field coils are key devices for generating magnetic fields in the field of magnetic metrology. With technological advancements, a new technology has been developed to address the in-situ calibration problem of fluxgate sensors (magnetometers), featuring an integrated calibration magnetic field coil, as shown in the attached diagram. Figure 1 As shown, this technology utilizes an enameled wire winding wound around the probe frame (or coaxial cable frame) of a 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 output magnetic field of the sensor meets the designed expected range of magnetic field change, the fluxgate sensor (magnetometer) can be calibrated.

[0003] Because this type of magnetic field coil is tightly integrated with the sensor probe, it can be considered a magnetic field coil with an iron core. Existing verification procedures and calibration standards cannot address the measurement methods used for this type of magnetic field coil. Current methods mainly include the magnetic field vector method, the magnetic field scalar method, and the standard coil method. All of these require placing a standard magnetometer inside the magnetic field coil being measured, and calibrating the magnetic field coil constant by measuring changes in magnetic induction intensity and excitation current. The common principles of existing calibration devices are shown in the appendix. Figure 2 As shown. However, the mechanical structure of the magnetic field coil with an iron core dictates that existing measurement methods cannot solve the calibration problem. Summary of the Invention

[0004] To address the problem of accurately measuring the constant of a hollow magnetic field coil, this disclosure provides a device for measuring the constant of a detection coil by utilizing changes in magnetic flux. This device utilizes the change in magnetic flux generated by a magnetic field coil with an iron core at the instant of energization / de-energization, then uses a magnetic flux measuring coil to measure this change, and finally calculates the constant of the magnetic field coil with the iron core. This solves the problem of the inability to measure the constant of a magnetic field coil with an iron core, and avoids the problem of large calculation errors in the coil constant caused by the inaccurate measurement of the iron core's permeability.

[0005] The magnetic flux variable-based magnetic field constant measurement device for an iron-core coil provided in this disclosure includes: 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 a coil with an iron core magnetic field via a sampling resistor;

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

[0008] A magnetic flux measuring coil is wrapped around a magnetic field coil with an iron core. It is used to sense changes in the magnetic flux passing through the magnetic flux measuring coil and generate an induced electromotive force.

[0009] The data acquisition module is used to measure the induced electromotive force of the magnetic flux measuring coil, calculate the change in magnetic flux ΔΦ, acquire the driving current I flowing to the core magnetic field coil, and calculate the coil constant of the core magnetic field coil based on the change in magnetic flux ΔΦ and the driving current I.

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

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

[0012] In a DC regulated power supply, the iron-core magnetic field coil is rapidly drawn from the center of the flux measurement coil while energized, providing a rapidly changing magnetic field signal to the flux measurement coil.

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

[0014] Furthermore, the magnetic flux measuring coil is characterized by one or more of the following features:

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

[0016] b) The structural form adopts a Helmholtz coil structure;

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

[0018] d) The wire frame is made of non-metallic, low-conductivity material and has chemical and physical stability at the expected operating temperature.

[0019] e) A grounded copper comb-shaped cladding is applied to the outside of the winding layer to reduce the influence of external electromagnetic interference coupled into the measurement coil during measurement.

[0020] Furthermore, the data acquisition module adopts a dual-channel data acquisition unit with an AD bit depth of 18 bits or more, a sampling rate of 10 kHz or more, and is matched to voltage pulse edges.

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

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

[0023] Let the measuring coil constant K of the pre-calibrated magnetic flux measuring coil be... Φ That is, the area of ​​the coil turns NA; the driving current through the coil with an iron core magnetic field is I, and the change in magnetic flux through the magnetic flux measuring coil is ΔΦ.

[0024]

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

[0026] Compared with the prior art, the beneficial effects of this disclosure are: (1) Compared with the prior art, it can solve the problem that the coil constant of the coil with iron core magnetic field cannot be measured; (2) The measuring device adopts magnetic flux measurement, which avoids the problem of large calculation error of coil constant caused by the inability to accurately measure the permeability of iron core; (3) The device is simple in composition; (4) The measurement and calculation process is convenient. Attached Figure Description

[0027] The above and other objects, features and advantages of this disclosure will become more apparent from the more detailed description of exemplary embodiments of this disclosure taken in conjunction with the accompanying drawings, in which the same reference numerals generally represent the same components.

[0028] Figure 1 A schematic diagram of a fluxgate sensor with a calibration magnetic field coil;

[0029] Figure 2 This describes the principle of a common magnetic field coil constant calibration device.

[0030] Figure 3 This is a schematic diagram of the system composition according to an exemplary embodiment of the present disclosure. Detailed Implementation

[0031] Preferred embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While preferred embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that the present disclosure will be thorough and complete, and will fully convey the scope of the present disclosure to those skilled in the art.

[0032] This disclosure provides a device for measuring the magnetic field constant of an "iron core" coil based on magnetic flux variation. The basic principle is explained below:

[0033] This device utilizes the interaction between a magnetic flux measuring coil and a magnetic field coil with an iron core, based on Faraday's law of electromagnetic induction. Specifically, it includes:

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

[0035] ε=-dΦ / dt (1)

[0036] Where ε is the induced electromotive force and Φ is the magnetic flux through the measuring coil.

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

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

[0039] In one exemplary implementation, the system structure is as shown in the appendix. Figure 3 As shown, it mainly includes: magnetic flux measurement coil, data acquisition unit, sampling resistor, and 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 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 resistance; d) the coil material has sufficient stability; and e) the coil has electromagnetic compatibility. In other words:

[0042] a) The uniform region of the magnetic flux measuring coil is large enough to accommodate the object being measured, and the volume of the 0.5% magnetic field uniform region is greater than 1 / 3 of the volume of the object being measured.

[0043] b) The magnetic flux measuring coil is usually constructed using a Helmholtz coil structure, which is convenient for handling and positioning.

[0044] c) The flux measurement coil ensures a sufficient number of turns to increase the amplitude of the induced electromotive force, while reducing the number of turns and resistance to reduce thermal noise. The standard design parameter is 50m. 2 The equivalent turn area is approximately 20 to 25 turns;

[0045] d) The wire frame is made of non-metallic, low-conductivity material that has chemical and physical stability at the expected operating temperature, such as polyoxymethylene.

[0046] e) Take measures such as grounded copper comb-shaped coverings on the outside of the winding layer to reduce the influence of external electromagnetic interference coupled into the measurement coil during measurement.

[0047] 2) Select a suitable dual-channel data acquisition unit in terms of AD bit depth and sampling rate. The main technical requirements are: the AD bit depth is sufficient to accurately identify the voltage signal change rate of 1μV, usually 18 bits or more is selected; the sampling rate reaches 10kHz or more, and it is matched to the voltage pulse edge.

[0048] 3) The sampling resistor should be composed of non-inductive resistors, with a resistance value between 1Ω and 10Ω.

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

[0050] The specific measurement process using the above equipment is as follows:

[0051] a) A step magnetic field signal is generated by a coil with an iron core.

[0052] The impact measurement method can be used, which involves using a pulse signal source to drive a coil with an iron core magnetic field.

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

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

[0055] c) Based on the measuring coil constant K of the pre-calibrated flux measuring coil. Φ (i.e., measuring the coil area NA), and the data acquisition unit obtains the driving current I (referring to the stable current provided by the signal source) through the iron-core magnetic field coil by measuring the voltage across the sampling resistor. The coil constant of the iron-core magnetic field coil is calculated using the formula: K B =ΔΦ / (K) Φ ·I), where K B It is the coil constant of a coil with an iron core and magnetic field.

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

[0057] The above technical solutions are merely exemplary embodiments of the present invention. For those skilled in the art, based on the application methods and principles disclosed in the present invention, it is easy to make various types of improvements or modifications, and not limited to the methods described in the specific embodiments of the present invention. Therefore, the methods described above are merely preferred and not restrictive.

Claims

1. A magnetic flux variable based constant measurement device for a magnetic field coil with a core, characterized by, The application relates to a magnetic flux measuring device, which comprises a signal source, a sampling resistor, a magnetic flux measuring coil and a data acquisition module, wherein the signal source is used for outputting current to the magnetic field coil with an iron core through the sampling resistor; the magnetic field coil with an iron core is used for providing a rapidly changing magnetic field signal to the magnetic flux measuring coil; the magnetic flux measuring coil is sleeved outside the magnetic field coil with an iron core and is used for sensing the change of the magnetic flux passing through the magnetic flux measuring coil to generate an induced electromotive force; the coil constant of the magnetic field coil with an iron core is calculated according to the following formula: the signal source adopts a pulse signal source for driving the magnetic field coil with an iron core to generate a step magnetic field signal or a direct-current stabilized power supply, in which case the magnetic field coil with an iron core provides the rapidly changing magnetic field signal to the magnetic flux measuring coil by being quickly pulled out from the center of the magnetic flux measuring coil in the charged state; the magnetic flux measuring coil is used for realizing the signal output between 0.1 mV and 1 V; the magnetic flux measuring coil has one or more of the following features: a) the uniform area is enough to accommodate the measured object, and the volume of the 0.5% magnetic field uniform area is greater than 1 / 3 of the volume of the measured object; b) the structural form adopts a Helmholtz coil structure; d) the wire frame is made of non-metallic and low-conductivity materials and has chemical and physical stability at the expected working environment temperature; e) the ground copper comb-shaped covering piece measure is adopted outside the winding layer to reduce the influence of the external electromagnetic interference coupled into the measuring coil during the measurement; the data acquisition module adopts a double-channel data acquisition device, the AD bit number is selected to be more than 18 bits, the sampling rate is selected to be more than 10 kHz, and the matching voltage pulse edge is selected; the sampling resistor is selected to be composed of non-inductive resistors, and the resistance value is between 1 ohm and 10 ohms. ​ ​ ​ ​ A data acquisition module is configured to measure an induced electromotive force of the magnetic flux measuring coil, calculate a magnetic flux change amount ΔΦ, and acquire a driving current flowing to the magnetic field coil with a core , and calculate a coil constant of the magnetic field coil with the core according to the magnetic flux change amount ΔΦ and the driving current I. ​ Let the measurement coil constant of a flux measuring coil previously calibrated be i.e. the measurement coil turn area ; the amount of change in the magnetic flux ΔΦ passing through the flux measuring coil, then the measurement coil constant of the flux measuring coil is wherein i.e. the coil constant of the magnetic field coil with core.

2. The apparatus of claim 1, wherein, ​ ​ ​ 3. The device of claim 1 or 2, characterized in that ​ 4. The apparatus of claim 3, wherein, ​ ​ ​ c) 50 m 2 Equivalent turns area, 20-25 turns; ​ ​ 5. The apparatus of claim 1 or 2, wherein, ​ 6. The apparatus of claim 1 or 2, wherein ​

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