Non-contact conductivity measuring device and method and storage medium

Abstract

The invention relates to a non-contact conductivity measuring device which comprises an RLC (Radio Link Control) circuit, a signal generator, an oscilloscope and a calculation module, wherein the RLC circuit is formed by connecting a resistor, a capacitor and an inductor in series; the inductor consists of 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 two ends of the capacitor and voltage signals at two ends of the input voltage source; the calculation module is used for obtaining the resonant frequency of the RLC circuit according to the ratio of the voltage signals at the two ends of the capacitor to the voltage signals at the two ends of the input voltage source; and the controller is also used for calculating the conductivity of the to-be-measured conductor rod according to the outer radius of the to-be-measured conductor rod, the outer radius of the solenoid, the length of the solenoid, the number of close winding turns of the solenoid, the capacitance value of the capacitor and the resonance frequency. It can be understood that by means of the technical scheme, the conductivity of the conductor rod can be measured in a non-contact mode, and the testing 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 electrical conductivity of a conductor and is widely used in materials science, chemical engineering, electronics industry, and other fields. Traditional conductivity measurement methods, such as the voltammetry method and the bridge balance method, require the conductor to be measured to be directly connected to the circuit for measurement, which is a contact 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 an unknown conductor.

[0004] In addition, the contact measurement method will inevitably damage the surface of the sample to be tested, especially those conductors with protective coatings or natural oxide layers, and active metals such as sodium, potassium, rubidium, cesium, etc. Once the surface is damaged, it may lead to serious consequences such as spontaneous combustion or explosion, 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 a 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 bar to be measured, and the conductor bar 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 according to the ratio of the voltage signal at both ends of the capacitor and the voltage signal at both ends of the input voltage source; and is also used to calculate the conductivity of the conductor rod to be measured 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 densely 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] According to the following formula, the conductivity of the conductor rod to be tested is calculated:

[0014]

[0015] Among them, σ c is the conductivity of the conductor bar to be measured, f is the resonant frequency, a is the outer radius of the conductor bar 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 contactless 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 at both ends of the capacitor and the voltage signal at both ends of the input voltage source;

[0021] The calculation module is used to obtain the resonance 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 one of the above-mentioned devices, comprising:

[0025] Obtain the outer radius of the conductor rod to be tested, 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 according to the ratio of the voltage signal across the capacitor and the voltage signal across the input voltage source;

[0028] The conductivity of the conductor bar to be measured is calculated according to the outer radius of the conductor bar to be measured, the outer radius of the solenoid, the length of the solenoid, the number of densely wound 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] According to the obtained multiple groups of capacitance values ​​and resonant frequencies, multiple conductivity calculation results of the conductor rod to be tested are obtained.

[0032] Preferably, the calculating and obtaining the conductivity of the conductor rod to be measured comprises:

[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 air magnetic permeability, 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 according to the first relationship and the second relationship:

[0040]

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

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

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

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

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

[0046] It can be understood that the present invention shows a contactless conductivity measuring device, including 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 in the center of the solenoid; the signal generator is used as an input voltage source of the RLC circuit; the oscilloscope is used to monitor the voltage signal at both ends of the capacitor and the voltage signal at both ends of the input voltage source; the calculation module is used to obtain the resonant frequency of the RLC circuit according to the ratio of the voltage signal at both ends of the capacitor and the voltage signal at both ends of the input voltage source; it is also used to calculate the conductivity of the conductor rod to be measured 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 turns of the solenoid, the capacitance value of the capacitor and the resonant frequency. It can be 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 of the magnetic field and electric field distribution of a solenoid according to an exemplary embodiment;

[0052] Figure 4 is a diagram showing changes in magnitude of magnetic field and magnitude of electric field 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 shown 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] Fig. 9 FIG. 4 is a waterfall diagram of 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 shown in the accompanying drawings. When the following description refers to the drawings, the same numbers in different drawings represent the same or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Instead, they are merely examples of devices and methods consistent with some aspects of the present invention as detailed in the appended claims.

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

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

[0061] The inductor is composed of a solenoid and a conductor bar to be measured, and the conductor bar 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 according to the ratio of the voltage signal at both ends of the capacitor and the voltage signal at both ends of the input voltage source; and is also used to calculate the conductivity of the conductor rod to be measured 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 densely wound turns of the solenoid, the capacitance value of the capacitor and the resonant frequency.

[0065] It can be understood that a contactless conductivity measuring 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 in the center of the solenoid; the signal generator is used as an input voltage source of the RLC circuit; the oscilloscope is used to monitor the voltage signal at both ends of the capacitor and the voltage signal at both ends of the input voltage source; the calculation module is used to obtain the resonant frequency of the RLC circuit according to the ratio of the voltage signal at both ends of the capacitor and the voltage signal at both ends of the input voltage source; and it is also used to calculate the conductivity of the conductor rod to be measured 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 turns of the solenoid, the capacitance value of the capacitor and the resonant frequency. It can be understood that the technical solution shown in this embodiment can measure the conductivity of the conductor rod without contact, and the test accuracy is high.

[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] According to the following formula, the conductivity of the conductor rod to be tested is calculated:

[0068]

[0069] Among them, σ c is the conductivity of the conductor bar to be measured, f is the resonant frequency, a is the outer radius of the conductor bar 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 conductance c :

[0075]

[0076] AC resonance refers to the phenomenon that in an AC series RLC circuit, at a certain frequency, the interaction between the inductance, capacitance and resistance causes the impedance of the circuit to reach a minimum value. 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 is independent of frequency; the inductive reactance Z L =2πfl, proportional to the frequency; the capacitive reactance of the capacitor Inversely proportional to frequency.

[0079] Resonance occurs when the inductive reactance and the 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, we can get the resonant frequency f0:

[0084]

[0085] At the resonant frequency f0, the inductive reactance and capacitive reactance 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 the lowest, the current reaches its maximum value, the phase difference between the 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 the largest, that is, when resonance is reached, the voltage division of each circuit element 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 way to use the maximum voltage division of the inductor or capacitor to determine whether the resonant frequency has been reached.

[0088] Since the conductor rod inserted in the solenoid generates eddy currents, it forms a transformer-like working condition with the solenoid. Therefore, the eddy current loss generated in the conductor will also be reflected back to the solenoid, forming an additional resistance. Therefore, measuring the voltage across the solenoid actually measures the voltage division of the inductance, additional resistance, and enameled wire resistance, which interferes with the determination of the resonant frequency. However, measuring the voltage across the capacitor will not cause the above problem.

[0089] Therefore, we choose to find the frequency f0 corresponding to the maximum voltage across the capacitor by scanning the oscilloscope, which is used to calculate the measured inductance value, and finally converted into the measured metal inductance value based on the theoretical expression.

[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 value 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, see Figure 2 , it 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 intensity.

[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 control equation and gauge equation under quasi-steady field into:

[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 tangent 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: 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 bar: The tangential component of the magnetic field intensity is continuous, then:

[0122] H 内 (ρ)=H 外 (ρ)

[0123] Magnetic field boundaries 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 control 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 a sinusoidal alternating current is flowing through the circuit The distribution of magnetic field and electric field 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 represents the change of magnetic field magnitude over time, see Figure 4 .

[0132]

[0133] Exact solution for the electric field distribution:

[0134] remember Indicates that the electric field is an eddy electric field along Directions, 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, σ is 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. By the continuity boundary condition of E, the electric field in the solenoid wire is:

[0138]

[0139] Integrating along the electric field lines gives:

[0140] Inductor voltage division:

[0141]

[0142] Points:

[0143]

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

[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] The approximate solution of the 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 according to the ratio of the voltage signal across the capacitor and the voltage signal across the input voltage source, it 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 tested, 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 tested can be calculated by combining the number of densely wound turns of the solenoid and substituting it into the formula.

[0164] It should be noted that, in the contactless conductivity measurement 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 at both ends of the capacitor and the voltage signal at both ends of the input voltage source; 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 c The value of / U0 also plots the frequency sweep, see Figure 7 . Read the frequency sweep diagram, U c The frequency f when the value of / U0 is maximum and the corresponding quality factor Q.

[0167] The conductor rods are selected to be non-ferromagnetic conductors: copper, aluminum, tungsten, molybdenum, zinc, chromium, lead, titanium, graphite. The theoretical resonance curves of all measured conductors and the waterfall diagrams of the actual measurement points are shown in 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 change the capacitance value connected to the circuit, and the resonant frequency will change accordingly. 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 caused by poor contact when clamping the capacitor pins with alligator clips when using a multimeter directly, a breadboard was used separately, and a capacitance measurement module was built using the jacks and wires on it. The capacitance measurement module can connect the monolithic capacitor to the measurement circuit in a stable and reliable way, so that its capacitance value can be read more accurately. In this way, the reliability of the measurement data can be further improved.

[0177] For data processing, experimentally measured values ​​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 capacitor to change the resonant frequency of the circuit, the inductance values ​​at different frequencies are obtained, and compared with the standard inductance value, the theoretical inductance waterfall diagram of each conductor bar is obtained, see Fig. 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, with the same trend and only a small deviation.

[0191] 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 one of the above-mentioned devices, comprising:

[0192] Obtain the outer radius of the conductor rod to be tested, the outer radius of the solenoid, the length of the solenoid, and the number of densely wound turns of the solenoid;

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

[0194] The resonant frequency of the RLC circuit is obtained according to the ratio of the voltage signal across the capacitor and the voltage signal across the input voltage source;

[0195] The conductivity of the conductor bar to be measured is calculated according to the outer radius of the conductor bar to be measured, the outer radius of the solenoid, the length of the solenoid, the number of densely wound turns of the solenoid, the capacitance value of the capacitor and the resonant frequency.

[0196] It should be noted that the contactless conductivity measurement method based on AC resonance further includes:

[0197] The capacitance value of the capacitor in the RLC circuit is changed multiple times to obtain the resonant frequency corresponding to each capacitance value;

[0198] According to the obtained multiple groups of capacitance values ​​and resonant frequencies, multiple conductivity calculation results of the conductor rod to be tested are obtained.

[0199] It should be noted that the calculation to obtain the conductivity of the conductor rod to be tested includes:

[0200] The first relationship between conductivity and inductance is obtained according to electrodynamics calculation:

[0201]

[0202] 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 air magnetic permeability, N is the number of turns of the solenoid, l is the length of the solenoid; L is the inductance;

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

[0204]

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

[0206] The conductivity calculation formula is obtained according to the first relationship and the second relationship:

[0207]

[0208] The conductivity of the conductor rod to be tested 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] According to the capacitance value of the capacitor in the RLC circuit and the resonant frequency, the inductance value of the inductor in the RLC circuit is obtained.

[0211] According to a third aspect of an embodiment of the present invention, a computer-readable storage medium is provided, storing a computer program, and when the computer program is executed by a processor, the method described in any one of the above 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 only used for descriptive purposes and cannot be understood as indicating or implying relative importance. In addition, in the description of the present invention, unless otherwise specified, the meaning of "plurality" refers to 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 that includes 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 not be performed in 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 belong.

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

[0216] A person skilled in the art may understand that all or part of the steps in the method for implementing the above-mentioned embodiment may be completed by instructing related hardware through a program, and the program may be stored in a computer-readable storage medium, which, when executed, includes one or a combination of the steps of the method embodiment.

[0217] In addition, each functional unit in each embodiment of the present invention may be integrated into a processing module, or each unit may exist physically separately, or two or more units may be integrated into one module. The above-mentioned integrated module may be implemented in the form of hardware or in the form of a software functional module. If the integrated module is implemented in the form of a software functional module and sold or used as an independent product, it 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] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0220] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary 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 bar to be measured, and the conductor bar 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 used to obtain the resonant frequency of the RLC circuit according to the ratio of the voltage signal at both ends of the capacitor and the voltage signal at both ends of the input voltage source; and is also used to calculate the conductivity of the conductor rod to be measured 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 densely wound turns of the solenoid, the capacitance value of the capacitor and the resonant frequency.

2. The non-contact conductivity measuring device according to claim 1, characterized in that: When calculating the conductivity of the conductor rod to be tested, the calculation module includes: According to the following formula, the conductivity of the conductor rod to be tested is calculated: Among them, σ c is the conductivity of the conductor bar to be measured, f is the resonant frequency, a is the outer radius of the conductor bar 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.

3. The non-contact conductivity measuring device according to claim 1, characterized in that: When the calculation module obtains the resonant frequency of the RLC circuit according to the ratio of the voltage signal at both ends of the capacitor and the voltage signal at both ends of the input voltage source, the calculation module includes: Calculate the voltage ratio of the voltage signal across the capacitor to the voltage signal across the input voltage source; When the voltage ratio is maximum, the frequency of the RLC circuit at this time is obtained as the resonant frequency.

4. The non-contact conductivity measuring device according to claim 3, 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 at both ends of the capacitor and the voltage signal at both ends of the input voltage source; The calculation module is used to obtain the resonance frequency according to the frequency sweep image.

5. 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.

6. A non-contact conductivity measurement method based on AC resonance, characterized in that: The device as claimed in any one of claims 1 to 5 comprises: Obtain the outer radius of the conductor rod to be tested, 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 according to the ratio of the voltage signal across the capacitor and the voltage signal across the input voltage source; The conductivity of the conductor bar to be measured is calculated according to the outer radius of the conductor bar to be measured, the outer radius of the solenoid, the length of the solenoid, the number of densely wound turns of the solenoid, the capacitance value of the capacitor and the resonant frequency.

7. The contactless conductivity measurement method based on AC resonance according to claim 6 is 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; According to the obtained multiple groups of capacitance values ​​and resonant frequencies, multiple conductivity calculation results of the conductor rod to be tested are obtained.

8. The contactless conductivity measurement method based on AC resonance according to claim 6, 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 air magnetic permeability, 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 according to the first relationship and the second relationship: The conductivity of the conductor rod to be tested is calculated according to the conductivity calculation formula.

9. The contactless conductivity measurement method based on AC resonance according to claim 6, characterized in that: Also includes: According to the capacitance value of the capacitor in the RLC circuit and the resonant frequency, the inductance value of the inductor in the RLC circuit is obtained.

10. 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 6 to 9 is implemented.

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