A contactless conductivity measurement device, method, and storage medium

Abstract

The application relates to a non-contact conductivity measuring device which comprises an RLC circuit formed by series connection of resistance, capacitance and inductance, a signal generator, an oscilloscope and a calculation module; the inductance is formed by a solenoid and a conductor rod arranged in the center of the solenoid; the signal generator serves as an input voltage source of the RLC circuit; the oscilloscope is used for monitoring voltage signals at both ends of the capacitance and at both ends of the input voltage source; the calculation module is used for obtaining a resonance frequency of the RLC circuit according to a ratio of the voltage signals at both ends of the capacitance and at both ends of the input voltage source; and the calculation module is also used for calculating the conductivity of a conductor rod to be measured according to an outer radius of the conductor rod to be measured, an outer radius of the solenoid, a length of the solenoid, a tightly-wound turn number of the solenoid, a capacitance value of the capacitance and the resonance frequency. It can be understood that the technical scheme shown in the application can non-contact measure the conductivity of the conductor rod, and the test accuracy is high.

Description

Technical Field

[0001] The present invention relates to the technical field of conductivity measurement, and in particular to a contactless conductivity measurement device, method and storage medium. Background Art

[0002] Conductivity is an important physical quantity that measures the ability of a conductor to conduct electricity and is widely used in fields such as materials science, chemical engineering, and electronics. Traditional conductivity measurement methods, such as voltammetry and bridge balance, require the conductor to be directly connected to the circuit for measurement, which is a contact-based measurement.

[0003] However, these contact measurement methods have significant drawbacks: although the voltammetry method can measure resistance, it is only applicable to poor conductors and is difficult to accurately measure low-resistance conductors; the bridge balance method requires finding a metal wire with a conductivity close to that of the conductor to be measured as a reference, which is particularly difficult when facing unknown conductors.

[0004] In addition, contact measurement methods inevitably damage the surface of the sample to be tested, especially conductors with protective coatings or natural oxide layers, as well as active metals such as sodium, potassium, rubidium, and cesium. Once the surface is damaged, serious consequences such as spontaneous combustion or explosion may occur, further limiting the scope of application of traditional methods. Summary of the Invention

[0005] In view of this, an object of the present invention is to provide a contactless conductivity measurement device, method and storage medium to solve the problem in the prior art that the surface of the sample to be measured needs to be contacted when measuring conductivity.

[0006] According to a first aspect of an embodiment of the present invention, there is provided a contactless conductivity measuring device, comprising:

[0007] An RLC circuit consisting of a resistor, a capacitor, and an inductor in series, a signal generator, an oscilloscope, and a calculation module;

[0008] The inductor is composed of a solenoid and a conductor rod to be measured, and the conductor rod to be measured is placed at the center of the solenoid;

[0009] The signal generator serves as an input voltage source of the RLC circuit;

[0010] The oscilloscope is used to monitor the voltage signal across the capacitor and the voltage signal across the input voltage source;

[0011] The calculation module is used to obtain the resonant frequency of the RLC circuit based on the ratio of the voltage signal across the capacitor and the voltage signal across the input voltage source; and is also used to calculate the conductivity of the conductor rod to be measured based on the outer radius of the conductor rod to be measured, the outer radius of the solenoid, the length of the solenoid, the number of tightly wound turns of the solenoid, the capacitance value of the capacitor and the resonant frequency.

[0012] Preferably, in the contactless conductivity measuring device, when the calculation module calculates the conductivity of the conductor rod to be measured, it includes:

[0013] The conductivity of the conductor rod to be tested is calculated according to the following formula:

[0014]

[0015] Among them, σ c is the conductivity of the conductor rod to be measured, f is the resonant frequency, a is the outer radius of the conductor rod to be measured, b is the outer radius of the solenoid, C is the capacitance value of the capacitor, N is the number of turns of the solenoid, and l is the length of the solenoid.

[0016] Preferably, in the contactless conductivity measuring device, when the calculation module obtains the resonant frequency of the RLC circuit according to the ratio of the voltage signal across the capacitor and the voltage signal across the input voltage source, the calculation module includes:

[0017] Calculate the voltage ratio of the voltage signal across the capacitor to the voltage signal across the input voltage source;

[0018] When the voltage ratio is maximum, the frequency of the RLC circuit at this time is obtained as the resonant frequency.

[0019] Preferably, in the non-contact conductivity measuring device, the calculation module at least includes: a frequency response analyzer;

[0020] The frequency response analyzer is used to generate a frequency sweep image according to the voltage signal across the capacitor and the voltage signal across the input voltage source;

[0021] The calculation module is used to obtain the resonant frequency according to the frequency sweep image.

[0022] Preferably, the contactless conductivity measuring device further comprises:

[0023] The capacitance measuring module is used to measure the capacitance value of the capacitor.

[0024] According to a second aspect of an embodiment of the present invention, there is provided a contactless conductivity measurement method based on AC resonance, which is applied to any of the above-mentioned devices, comprising:

[0025] Obtain the outer radius of the conductor rod to be measured, the outer radius of the solenoid, the length of the solenoid, and the number of densely wound turns of the solenoid;

[0026] Get the capacitance value of the capacitor in the RLC circuit;

[0027] The resonant frequency of the RLC circuit is obtained based on the ratio of the voltage signal across the capacitor to the voltage signal across the input voltage source;

[0028] The conductivity of the conductor rod to be measured is calculated according to the outer radius of the conductor rod to be measured, the outer radius of the solenoid, the length of the solenoid, the number of dense turns of the solenoid, the capacitance value of the capacitor and the resonant frequency.

[0029] Preferably, the contactless conductivity measurement method based on AC resonance further includes:

[0030] The capacitance value of the capacitor in the RLC circuit is changed multiple times to obtain the resonant frequency corresponding to each capacitance value;

[0031] Based on the obtained multiple sets of capacitance values ​​and resonant frequencies, multiple conductivity calculation results of the conductor rod to be measured are obtained.

[0032] Preferably, the calculation to obtain the conductivity of the conductor rod to be measured includes:

[0033] The first relationship between conductivity and inductance is obtained according to electrodynamics calculation:

[0034]

[0035] Among them, σ c is the conductivity of the conductor bar to be measured, ω is the angular frequency, μ is the magnetic permeability, a is the outer radius of the conductor bar to be measured, b is the outer radius of the solenoid, μ0 is the magnetic permeability of air, N is the number of turns of the solenoid, l is the length of the solenoid; L is the inductance;

[0036] According to the response characteristics of the AC resonant circuit, the second relationship between inductance, resonant frequency and capacitance is obtained:

[0037]

[0038] Wherein, L is the inductance, f is the resonant frequency, and C is the capacitance value of the capacitor;

[0039] The conductivity calculation formula is obtained based on the first and second relationship formulas:

[0040]

[0041] The conductivity of the conductor rod to be measured is calculated according to the conductivity calculation formula.

[0042] Preferably, the contactless conductivity measurement method based on AC resonance further includes:

[0043] The inductance value of the inductor in the RLC circuit is obtained according to the capacitance value of the capacitor in the RLC circuit and the resonant frequency.

[0044] According to a third aspect of an embodiment of the present invention, a computer-readable storage medium is provided, storing a computer program, wherein when the computer program is executed by a processor, any of the above methods is implemented.

[0045] The technical solutions provided by the embodiments of the present invention may have the following beneficial effects:

[0046] It is understood that the present invention shows a contactless conductivity measurement device, which includes an RLC circuit composed of a resistor, a capacitor, and an inductor connected in series, a signal generator, an oscilloscope, and a calculation module; the inductor is composed of a solenoid and a conductor rod placed at the center of the solenoid; the signal generator serves as the input voltage source of the RLC circuit; the oscilloscope is used to monitor the voltage signal across the capacitor and the voltage signal across the input voltage source; the calculation module is used to obtain the resonant frequency of the RLC circuit based on the ratio of the voltage signal across the capacitor and the voltage signal across the input voltage source; and is also used to calculate the conductivity of the conductor rod to be measured based on the outer radius of the conductor rod to be measured, the outer radius of the solenoid, the length of the solenoid, the number of turns of the solenoid, the capacitance value of the capacitor, and the resonant frequency. It is understood that the technical solution shown in the present invention can measure the conductivity of the conductor rod without contact, and the test accuracy is high.

[0047] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0049] Figure 1 is a schematic block diagram of wiring of a contactless conductivity measuring device according to an exemplary embodiment;

[0050] Figure 2 is a schematic cross-sectional view of a solenoid according to an exemplary embodiment;

[0051] Figure 3 is a schematic diagram showing the distribution of magnetic and electric fields of a solenoid according to an exemplary embodiment;

[0052] Figure 4 is a diagram showing changes in magnetic field and electric field magnitudes of a solenoid according to an exemplary embodiment;

[0053] Figure 5 is a function plotting diagram shown according to an exemplary embodiment;

[0054] Figure 6 is an image of an exact solution function according to an exemplary embodiment;

[0055] Figure 7 is a schematic diagram of a frequency sweep image according to an exemplary embodiment;

[0056] Figure 8 is a waterfall diagram showing theoretical resonance curves of all measured conductors and actual measurement points according to an exemplary embodiment;

[0057] Figure 9 FIG. 1 is a waterfall diagram showing the theoretical inductance of each conductor bar according to an exemplary embodiment. DETAILED DESCRIPTION

[0058] Exemplary embodiments will be described in detail herein, examples of which are illustrated in the accompanying drawings. In the following description, when referring to the drawings, like numbers in different figures represent like or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments are not intended to represent all possible embodiments consistent with the present invention. Rather, they are merely examples of apparatus and methods consistent with certain aspects of the present invention, as detailed in the appended claims.

[0059] In one embodiment, Figure 1 is a wiring diagram of a non-contact conductivity measuring device according to an exemplary embodiment. Figure 1 , providing a non-contact conductivity measuring device, comprising:

[0060] RLC circuit composed of resistor, capacitor and inductor in series, signal generator, oscilloscope, calculation module (in Figure 1 not shown in the figure);

[0061] The inductor is composed of a solenoid and a conductor rod to be measured, and the conductor rod to be measured is placed at the center of the solenoid;

[0062] The signal generator serves as an input voltage source of the RLC circuit;

[0063] The oscilloscope is used to monitor the voltage signal across the capacitor and the voltage signal across the input voltage source;

[0064] The calculation module is used to obtain the resonant frequency of the RLC circuit based on the ratio of the voltage signal across the capacitor and the voltage signal across the input voltage source; and is also used to calculate the conductivity of the conductor rod to be measured based on the outer radius of the conductor rod to be measured, the outer radius of the solenoid, the length of the solenoid, the number of tightly wound turns of the solenoid, the capacitance value of the capacitor and the resonant frequency.

[0065] It is understood that the contactless conductivity measurement device shown in this embodiment includes an RLC circuit composed of a resistor, a capacitor, and an inductor connected in series, a signal generator, an oscilloscope, and a calculation module; the inductor is composed of a solenoid and a conductor rod placed at the center of the solenoid; the signal generator serves as the input voltage source of the RLC circuit; the oscilloscope is used to monitor the voltage signal across the capacitor and the voltage signal across the input voltage source; the calculation module is used to obtain the resonant frequency of the RLC circuit based on the ratio of the voltage signal across the capacitor to the voltage signal across the input voltage source; and is also used to calculate the conductivity of the conductor rod to be measured based on the outer radius of the conductor rod to be measured, the outer radius of the solenoid, the length of the solenoid, the number of turns of the solenoid, the capacitance value of the capacitor, and the resonant frequency. It is understood that the technical solution shown in this embodiment can measure the conductivity of the conductor rod without contact and with high test accuracy.

[0066] It should be noted that, in the contactless conductivity measuring device, when the calculation module calculates the conductivity of the conductor rod to be measured, it includes:

[0067] The conductivity of the conductor rod to be tested is calculated according to the following formula:

[0068]

[0069] Among them, σ c is the conductivity of the conductor rod to be measured, f is the resonant frequency, a is the outer radius of the conductor rod to be measured, b is the outer radius of the solenoid, C is the capacitance value of the capacitor, N is the number of turns of the solenoid, and l is the length of the solenoid.

[0070] According to the eddy current principle, when an alternating current passes through a solenoid coil, a changing magnetic field is generated around it, which in turn induces eddy currents inside the conductor to be measured (whether it is a solid rod conductor or a liquid in a liquid container). The magnetic field generated by the eddy current will in turn affect the inductance of the solenoid coil. This effect is directly related to the conductivity of the conductor, and the conductivity σ can be directly calculated through electrodynamics. c Approximate relationship with inductance value L:

[0071]

[0072] By directly measuring the response characteristics of the AC resonant circuit (such as the change in resonant frequency), the inductance value can be indirectly measured:

[0073]

[0074] Then the conductivity σ of the conductor is indirectly calculated through the relationship between inductance and conductivity c :

[0075]

[0076] AC resonance refers to the phenomenon in an AC series RLC circuit where, at a specific frequency, the interaction between the inductor, capacitor, and resistor causes the circuit's impedance to reach a minimum. This specific frequency is called the resonant frequency.

[0077] The series RLC circuit consists of a resistor R, an inductor L, and a capacitor C in series. For alternating current, its total impedance Z consists of three parts:

[0078] The resistance R, which is independent of frequency; the inductive reactance Z of the inductor L =2πfl, proportional to the frequency; the capacitive reactance of the capacitor Inversely proportional to frequency.

[0079] Resonance occurs when the inductive reactance and capacitive reactance are equal in magnitude and opposite in direction, that is:

[0080] Z L =Z C

[0081] at this time:

[0082]

[0083] From the above formula, the resonant frequency f0 can be obtained:

[0084]

[0085] At the resonant frequency f0, the inductive and capacitive reactances of the circuit cancel each other out, causing the total impedance Z of the circuit to be minimal, leaving only the resistance R: Z = R.

[0086] At this point, the impedance of the circuit is lowest, the current reaches its maximum value, the phase difference between voltage and current is zero, and the circuit behaves as a pure resistor.

[0087] When using AC resonance to measure inductance, according to the characteristics of series RLC AC resonance, when the current is maximum, that is, when resonance is reached, the voltage division of each circuit component reaches the maximum. The voltage division across the inductor and capacitor can be several times or even dozens of times higher than the power supply voltage. Therefore, it is a good method to use the maximum voltage division of the inductor or capacitor to determine whether the resonant frequency has been reached.

[0088] Because the conductor rod inserted into the solenoid generates eddy currents, it operates similarly to a transformer. Consequently, the eddy current losses generated in the conductor are reflected back into the solenoid, creating an additional resistance. Therefore, measuring the voltage across the solenoid actually measures the voltage divided by the inductance, the additional resistance, and the resistance of the enameled wire, which interferes with the determination of the resonant frequency. However, measuring the voltage across a capacitor avoids this problem.

[0089] Therefore, we choose to use the oscilloscope to sweep the frequency to find the frequency f0 corresponding to the maximum voltage across the capacitor, which is used to calculate the measured inductance value, and finally combined with the theoretical expression to convert it into the measured metal inductance value.

[0090]

[0091] Among them, U C is the voltage value across the capacitor; U0 is the voltage value across the input voltage source; U L is the voltage across the inductor; Z C is the capacitance impedance; R 总 is the total resistance; ω0 is the angular frequency; C is the capacitance; Z L is the inductor impedance; L is the inductance; Q is the quality factor.

[0092] ω0=2πf0

[0093] So the measured value of inductance is:

[0094]

[0095] The relationship between conductivity and inductance is calculated based on electrodynamics as follows:

[0096] Regarding the electrodynamic equations and boundary conditions, the direction of the magnetic field in the solenoid is perpendicular to the paper as shown in the figure. Figure 2 , which is approximately considered to satisfy the conditions of an ideal solenoid.

[0097] The conductor bar is located in the center of the solenoid. In the conductor bar area:

[0098] B=μH (μ remains unchanged)

[0099] Among them, B is the magnetic induction intensity; μ is the magnetic permeability; H is the magnetic field strength.

[0100] Assume that the field inside the conductor is harmonic, that is: E = E0e -iωt , then:

[0101]

[0102] Among them, j 位 is the displacement current density; j 传 is the conduction current density; ε is the relative dielectric constant.

[0103] The condition for ignoring displacement current is |j 位 / j 传 |<<1, requirement ω<<10 17 s -1 .

[0104] Substitute the quasi-steady field conditions into Maxwell's equations:

[0105]

[0106] j is the current density; ρ e is the stacking charge density.

[0107] Substitute the general governing equations and gauge equations under quasi-steady fields:

[0108] B=μH,D=εE

[0109]

[0110] j=σ c E

[0111] ρ e =0

[0112] The field equations of the electric field and magnetic field under this condition can be solved immediately:

[0113]

[0114] The equations for E and H under quasi-steady conditions are diffusion equations.

[0115] Consider the boundary conditions: the magnetic field intensity H and the electric field intensity E are continuous in the tangential direction. The boundary value relationship between the magnetic induction intensity B and the electric displacement vector D in the normal direction.

[0116] Magnetic field inside and outside the solenoid: Considered as an ideal solenoid, we have:

[0117]

[0118] n is the number of coil turns per unit length; I0 is the coil current.

[0119] Electric field inside and outside the solenoid: If the eddy electric field intensity is continuous, then:

[0120] E 管外 (b) = E 管内 (b)

[0121] Magnetic field boundaries inside and outside the conductor rod: The tangential component of the magnetic field intensity is continuous, then:

[0122] H 内 (ρ)=H 外 (ρ)

[0123] The magnetic field boundary inside and outside the conductor rod: the eddy electric field intensity is continuous, then:

[0124] E 棒外 (a) = E 棒内 (a)

[0125] The field governing equation under the boundary conditions of the column function is the diffusion equation:

[0126]

[0127] Exact electrodynamic solution for the change in inductance:

[0128] Consider the outer radius of the solenoid to be b and the inner conductor rod to be of radius a.

[0129] Assume that sinusoidal alternating current flows through the circuit The distribution of magnetic and electric fields can be solved:

[0130] Exact solution of magnetic field distribution:

[0131] remember Indicates that the direction of the magnetic field is along the z-axis, see Figure 3 Upper part; H(ρ) represents the magnitude of the magnetic field, e -iωt Indicates that the magnitude of the magnetic field changes with time, see Figure 4 .

[0132]

[0133] Exact solution of electric field distribution:

[0134] remember Indicates that the electric field is an eddy electric field along Direction, see Figure 3 Lower part; E(ρ) represents the magnitude of the electric field, e -iωt represents the change of magnetic field magnitude over time, see Figure 4 .

[0135]

[0136] Find special solutions involving complex numbers:

[0137] In the above formula, J0 and J1 are Bessel functions, μ is the magnetic permeability, and σ is the c is the conductivity, ρ is the distance from the center of the circle, k is the inverse of the skin depth, μ0 is the vacuum permeability, and i is the imaginary unit. Due to the continuity boundary condition of E, the electric field in the solenoid wire is:

[0138]

[0139] Integrating along the electric field lines yields:

[0140] Inductor voltage division:

[0141]

[0142] Points earned:

[0143]

[0144] According to the complex impedance theory, we can simplify the solution to:

[0145] inductance:

[0146]

[0147] Eddy current loss resistance:

[0148]

[0149] The imaginary and real parts of the above equation can be solved separately using the Bessel function addition formula and the imaginary quantity Bessel function, and the numerical value can be calculated using computer programming.

[0150] J1(x(i+1)), J0(x(i+1)) and See the programming calculation function for Figure 5 .

[0151] Program to draw the exact solution of electrodynamics L(ω) and R L (ω) function graph see Figure 6 .

[0152] Approximate solution of exact solution under certain conditions:

[0153] In the frequency range required for measurement |k 2 |=μσ c If ω is large enough, the approximate formula of the Bessel function can be obtained:

[0154]

[0155] The inductance is approximately expressed as:

[0156]

[0157] in,

[0158] In specific practice, the first step is to measure basic physical quantities, such as the outer radius of the conductor rod to be measured, the outer radius of the solenoid, the length of the solenoid, and the capacitance value of the capacitor.

[0159] Connect one channel of the oscilloscope to both ends of the capacitor to monitor the voltage signal across the capacitor; connect the other channel of the oscilloscope to both ends of the input voltage source (signal generator); use the oscilloscope to perform automatic frequency sweep, and at the same time, the oscilloscope monitors the output voltage in real time.

[0160] It should be noted that, in the contactless conductivity measuring device, when the calculation module obtains the resonant frequency of the RLC circuit based on the ratio of the voltage signal across the capacitor to the voltage signal across the input voltage source, the calculation module includes:

[0161] Calculate the voltage ratio of the voltage signal across the capacitor to the voltage signal across the input voltage source;

[0162] When the voltage ratio is maximum, the frequency of the RLC circuit at this time is obtained as the resonant frequency.

[0163] After obtaining the outer radius of the conductor rod to be measured, the outer radius of the solenoid, the length of the solenoid, the capacitance value of the capacitor and the resonant frequency, the conductivity of the conductor rod to be measured can be calculated by combining the number of densely wound turns of the solenoid and substituting them into the formula.

[0164] It should be noted that, in the non-contact conductivity measuring device, the calculation module at least includes: a frequency response analyzer;

[0165] The frequency response analyzer is used to generate a frequency sweep image according to the voltage signal across the capacitor and the voltage signal across the input voltage source; and the calculation module is used to obtain the resonant frequency according to the frequency sweep image.

[0166] In practice, a frequency response analyzer can record the U c The value of / U0 also plots the frequency sweep image, see Figure 7 . Read the frequency sweep diagram, U c The frequency f at which the value of / U0 is maximum and the corresponding quality factor Q.

[0167] The conductor rods are made of non-ferromagnetic conductors: copper, aluminum, tungsten, molybdenum, zinc, chromium, lead, titanium, and graphite. The theoretical resonance curves and waterfall diagrams of all measured conductors are shown in the table below. Figure 8 .

[0168] The data obtained from the first experiment are shown in Table 1, and the data obtained from the second experiment are shown in Table 2.

[0169] Table 1

[0170]

[0171] Table 2

[0172]

[0173] Then, by changing the capacitance value connected to the circuit, the resonant frequency will also change. Use the same method to measure and record the resonant frequency f and quality factor Q corresponding to different capacitance values.

[0174] It should be noted that the contactless conductivity measuring device further includes:

[0175] The capacitance measuring module is used to measure the capacitance value of the capacitor.

[0176] In practice, when measuring the capacitance of a monolithic capacitor, in order to avoid the error that may be introduced by poor contact when clamping the capacitor pins with alligator clips when using a multimeter directly, a separate breadboard was used, and a capacitance measurement module was constructed using the jacks and wires on it. The capacitance measurement module can connect the monolithic capacitor to the measurement circuit through a stable and reliable connection, thereby more accurately reading its capacitance value. In this way, the reliability of the measurement data can be further improved.

[0177] For data processing, experimental measurements of inductance:

[0178]

[0179] Theoretical inductance value:

[0180]

[0181] The conductivity σ can be solved immediately c :

[0182]

[0183] Measure the conductivity and basic measurement values ​​of customized pure copper, aluminum, tungsten, zinc, lead, molybdenum, titanium, chromium, and graphite. See Table 3 for basic measurement values ​​and Table 4 for conductivity.

[0184] Table 3

[0185]

[0186] Table 4

[0187]

[0188]

[0189] Compared with the standard conductivity, the errors are as follows: the reference conductivity of pure copper is 59.5, with an error of 1.80%; the reference conductivity of aluminum is 37.7, with an error of 2.81%; the reference conductivity of tungsten is 18.9, with an error of 2.54%; the reference conductivity of molybdenum is 17.5, with an error of 2.91%; the reference conductivity of zinc is 16.6, with an error of 3.25%; the reference conductivity of lead is 9.6, with an error of 1.88%; the reference conductivity of chromium is 7.8, with an error of 4.74%; the reference conductivity of titanium is 2.3, with an error of 2.17%.

[0190] By changing the resonant frequency of the circuit by replacing the capacitor, the inductance values ​​at different frequencies are obtained and compared with the standard inductance value. The theoretical inductance waterfall diagram of each conductor rod is obtained. Figure 9It can be seen that the measurement error is very small and the error bar is not obvious. It can be seen that the data points as a whole fall on the theoretical curve, the trend is the same, and there is only a small deviation.

[0191] According to a second aspect of the embodiments of the present application, a non-contact conductivity measurement method based on AC resonance is provided, applied to the device of any one of the above, comprising:

[0192] Obtaining the outer radius of the measured conductor rod, the outer radius of the solenoid, the length of the solenoid, and the densely wound turns of the solenoid;

[0193] Obtaining the capacitance value of the capacitor in the RLC circuit;

[0194] According to the ratio of the voltage signal across the capacitor and the voltage signal across the input voltage source, the resonance frequency of the RLC circuit is obtained;

[0195] According to the outer radius of the measured conductor rod, the outer radius of the solenoid, the length of the solenoid, the densely wound turns of the solenoid, the capacitance value of the capacitor, and the resonance frequency, the conductivity of the measured conductor rod is calculated.

[0196] It should be noted that the non-contact conductivity measurement method based on AC resonance further comprises:

[0197] Changing the capacitance value of the capacitor in the RLC circuit multiple times, and obtaining the resonance frequency corresponding to each capacitance value;

[0198] According to the obtained multiple sets of capacitance values and resonance frequencies, multiple conductivity calculation results of the measured conductor rod are obtained.

[0199] It should be noted that the calculation of the conductivity of the measured conductor rod comprises:

[0200] According to electrodynamic calculation, a first relationship between conductivity and inductance is obtained:

[0201]

[0202] Wherein, σ c is the conductivity of the measured conductor rod, ω is the angular frequency, μ is the magnetic permeability, a is the outer radius of the measured conductor rod, b is the outer radius of the solenoid, μ0 is the air magnetic permeability, N is the densely wound turns of the solenoid, and l is the length of the solenoid; L is the inductance;

[0203] According to the response characteristics of the AC resonance circuit, a second relationship between inductance, resonance frequency and capacitance is obtained:

[0204]

[0205] Wherein, L is the inductance, f is the resonance frequency, and C is the capacitance value of the capacitor;

[0206] The conductivity calculation formula is obtained based on the first and second relationship formulas:

[0207]

[0208] The conductivity of the conductor rod to be measured is calculated according to the conductivity calculation formula.

[0209] It should be noted that the contactless conductivity measurement method based on AC resonance further includes:

[0210] The inductance value of the inductor in the RLC circuit is obtained according to the capacitance value of the capacitor in the RLC circuit and the resonant frequency.

[0211] According to a third aspect of an embodiment of the present invention, a computer-readable storage medium is provided, storing a computer program, wherein when the computer program is executed by a processor, any of the above methods is implemented.

[0212] It can be understood that the same or similar parts of the above embodiments can be referenced to each other, and the contents not described in detail in some embodiments can refer to the same or similar contents in other embodiments.

[0213] It should be noted that, in the description of the present invention, the terms "first", "second", etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance. In addition, in the description of the present invention, unless otherwise specified, the meaning of "plurality" is at least two.

[0214] Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, segment or portion of code comprising one or more executable instructions for implementing the steps of a specific logical function or process, and the scope of the preferred embodiments of the present invention includes alternative implementations in which functions may be performed out of the order shown or discussed, including performing functions in a substantially simultaneous manner or in the reverse order depending on the functions involved, which should be understood by those skilled in the art to which the embodiments of the present invention pertain.

[0215] It should be understood that various parts of the present invention can be implemented using hardware, software, firmware, or a combination thereof. In the above-described embodiments, multiple steps or methods can be implemented using software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented using hardware, as in another embodiment, any one of the following technologies known in the art or a combination thereof can be used: a discrete logic circuit having a logic gate circuit for implementing a logic function on a data signal, an application-specific integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0216] Those skilled in the art will understand that all or part of the steps in the method of the above embodiment can be completed by instructing related hardware through a program, and the program can be stored in a computer-readable storage medium. When the program is executed, it includes one or a combination of the steps of the method embodiment.

[0217] In addition, the functional units in the various embodiments of the present invention may be integrated into a single processing module, or each unit may exist physically separately, or two or more units may be integrated into a single module. The aforementioned integrated modules may be implemented in the form of hardware or in the form of software functional modules. If the integrated modules are implemented in the form of software functional modules and sold or used as independent products, they may also be stored in a computer-readable storage medium.

[0218] The storage medium mentioned above can be a read-only memory, a magnetic disk or an optical disk, etc.

[0219] Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "examples," "specific examples," or "some examples" means that a specific feature, structure, material, or characteristic described in conjunction with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0220] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A non-contact conductivity measuring device, characterized in that: include: An RLC circuit consisting of a resistor, a capacitor, and an inductor in series, a signal generator, an oscilloscope, and a calculation module; The inductor is composed of a solenoid and a conductor rod to be measured, and the conductor rod to be measured is placed at the center of the solenoid; The signal generator serves as an input voltage source of the RLC circuit; The oscilloscope is used to monitor the voltage signal across the capacitor and the voltage signal across the input voltage source; The calculation module is configured to obtain the resonant frequency of the RLC circuit based on the ratio of the voltage signal across the capacitor to the voltage signal across the input voltage source, including: calculating the voltage ratio of the voltage signal across the capacitor to the voltage signal across the input voltage source; and when the voltage ratio is maximum, obtaining the frequency of the RLC circuit at that time as the resonant frequency; The calculation module is further configured to calculate the conductivity of the conductor rod to be measured based on the outer radius of the conductor rod to be measured, the outer radius of the solenoid, the length of the solenoid, the number of turns of the solenoid, the capacitance value of the capacitor, and the resonant frequency, using the following formula: Among them, σ c is the conductivity of the conductor rod to be measured, f is the resonant frequency, a is the outer radius of the conductor rod to be measured, b is the outer radius of the solenoid, C is the capacitance value of the capacitor, N is the number of turns of the solenoid, l is the length of the solenoid, μ is the magnetic permeability, and μ0 is the magnetic permeability of air.

2. The non-contact conductivity measuring device according to claim 1, characterized in that: The calculation module at least includes: a frequency response analyzer; The frequency response analyzer is used to generate a frequency sweep image according to the voltage signal across the capacitor and the voltage signal across the input voltage source; The calculation module is used to obtain the resonant frequency according to the frequency sweep image.

3. The non-contact conductivity measuring device according to claim 1, characterized in that: Also includes: The capacitance measuring module is used to measure the capacitance value of the capacitor.

4. A contactless conductivity measurement method based on AC resonance, characterized in that: The device according to any one of claims 1 to 3 comprises: Obtain the outer radius of the conductor rod to be measured, the outer radius of the solenoid, the length of the solenoid, and the number of densely wound turns of the solenoid; Get the capacitance value of the capacitor in the RLC circuit; The resonant frequency of the RLC circuit is obtained based on the ratio of the voltage signal across the capacitor to the voltage signal across the input voltage source; The conductivity of the conductor rod to be measured is calculated according to the outer radius of the conductor rod to be measured, the outer radius of the solenoid, the length of the solenoid, the number of dense turns of the solenoid, the capacitance value of the capacitor and the resonant frequency.

5. The contactless conductivity measurement method based on AC resonance according to claim 4, characterized in that: Also includes: The capacitance value of the capacitor in the RLC circuit is changed multiple times to obtain the resonant frequency corresponding to each capacitance value; Based on the obtained multiple sets of capacitance values ​​and resonant frequencies, multiple conductivity calculation results of the conductor rod to be measured are obtained.

6. The contactless conductivity measurement method based on AC resonance according to claim 5, characterized in that: The calculation to obtain the conductivity of the conductor rod to be measured includes: The first relationship between conductivity and inductance is obtained according to electrodynamics calculation: Among them, σ c is the conductivity of the conductor bar to be measured, ω is the angular frequency, μ is the magnetic permeability, a is the outer radius of the conductor bar to be measured, b is the outer radius of the solenoid, μ0 is the magnetic permeability of air, N is the number of turns of the solenoid, l is the length of the solenoid; L is the inductance; According to the response characteristics of the AC resonant circuit, the second relationship between inductance, resonant frequency and capacitance is obtained: Wherein, L is the inductance, f is the resonant frequency, and C is the capacitance value of the capacitor; The conductivity calculation formula is obtained based on the first and second relationship formulas: The conductivity of the conductor rod to be measured is calculated according to the conductivity calculation formula.

7. The contactless conductivity measurement method based on AC resonance according to claim 5, characterized in that: Also includes: The inductance value of the inductor in the RLC circuit is obtained according to the capacitance value of the capacitor in the RLC circuit and the resonant frequency.

8. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the method according to any one of claims 4 to 7 is implemented.

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