Capacitance measuring method and measuring system based on double LC resonance circuits

Abstract

The invention provides a capacitance measurement method and a capacitance measurement system based on double LC resonance circuits, which are applied to the technical field of laser cutting, and are characterized in that a reference circuit and a measurement circuit are arranged in the same environment and are LC resonance circuits with the same structure; the capacitance value measuring method of the to-be-measured capacitor comprises the following steps: S1, collecting the oscillation frequency of a reference circuit; s2, based on the circuit structure of the reference circuit and the oscillation frequency of the reference circuit, calculating the actual value of the inductance in the resonant circuit of the reference circuit, namely obtaining the actual value of the inductance in the resonant circuit of the measuring circuit at the current temperature; and S3, calculating the actual value of the capacitor to be measured in the measuring circuit at the current temperature based on the circuit structure of the measuring circuit, the oscillation frequency and the actual value of the inductor in the resonant circuit of the measuring circuit. A double-LC resonance circuit is used and comprises a reference circuit and a measuring circuit, so that the problem that capacitance measured by a single oscillation circuit is inaccurate due to temperature excursion can be solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of laser cutting, and in particular relates to a capacitance measurement method and a measurement system based on a double LC resonant circuit. Background Art

[0002] Laser cutting, as a high-precision, high-efficiency thermal processing technology, has been widely used in aerospace, automotive, sheet metal processing, and electronics industries. During the laser cutting process, the relative height between the cutting gun's metal nozzle and the metal sheet being processed has a crucial influence on the cutting quality. A gap that is too small can cause the nozzle to strike the sheet, while a gap that is too large can cause focus drift and a decrease in energy density, thereby reducing cutting quality. Furthermore, uneven workpiece surfaces during high-speed cutting can easily cause gap fluctuations. Therefore, a control system is required to monitor the distance between the cutting gun's metal nozzle and the metal sheet being processed in real time.

[0003] Currently, the mainstream method in this field uses capacitive height sensors for real-time detection. The basic principle is that a small capacitor forms between the cutting gun nozzle and the sheet material. The capacitance value changes with the distance between the nozzle and the sheet material. By measuring this small capacitance between the cutting gun nozzle and the sheet material using a capacitive detection circuit, the gap between the nozzle and the sheet material can be indirectly determined. Therefore, accurately measuring the capacitance between the metal nozzle and the sheet material is a prerequisite for accurately calculating the distance between the metal nozzle and the sheet material. However, in actual use, the accuracy of capacitive sensors is easily affected by temperature, resulting in poor measurement accuracy.

[0004] To eliminate the impact of temperature on the measurement accuracy of capacitive sensors, Chinese invention patent publication CN113741582B discloses a capacitance temperature compensation method and device. Using a precise capacitance measuring instrument, the actual capacitance of the capacitor under test is measured at different temperatures. Data on the change in temperature and capacitance are obtained. A curve is fitted based on the relationship between capacitance and temperature, and a compensation formula is derived.

[0005] Chinese invention patent publication CN119860798A discloses a capacitive proximity sensor and a method for compensating for temperature drift in a capacitive proximity sensor. The method comprises two circuits: a capacitance measurement circuit as the first circuit and a temperature compensation circuit as the second circuit. The method first measures the capacitance of the first circuit at different temperatures to determine how the capacitance varies with temperature. The output of the second circuit is then adjusted at different temperatures to obtain a mapping between the different temperatures and the output of the second circuit. Ultimately, the method ensures that "the first circuit output + the second circuit output = the actual capacitance value that does not vary with temperature." This method requires the determination of both mappings before use, which is complex and prone to errors.

[0006] Both of the above methods require a large amount of data collection on the changes in capacitance values ​​with temperature, and the mapping relationship between capacitance and temperature is obtained through experiments. Since data collection is discrete, and the temperature changes in the actual environment are subtle and continuous, and there are also other factors besides temperature that affect the measurement results, the above solutions are prone to errors. Summary of the Invention

[0007] In view of the above problems in the prior art, the purpose of the present invention is to provide a capacitance measurement method based on a dual LC resonant circuit. The dual LC resonant circuit, including a reference circuit and a measurement circuit, can solve the problem of inaccurate capacitance measured by a single oscillation circuit due to temperature drift.

[0008] A capacitance measurement method based on a dual LC resonant circuit, wherein a reference circuit and a measurement circuit are located at the top and bottom of the same circuit board, so that the reference circuit and the measurement circuit are in the same environment. The reference circuit and the measurement circuit are LC resonant circuits with the same structure, wherein the measurement circuit includes a capacitor to be measured, and the circuit element corresponding to the capacitor to be measured in the reference circuit is a C0G capacitor;

[0009] The method for measuring the capacitance value of the capacitor to be measured specifically includes the following steps:

[0010] S1, collecting the oscillation frequency of the reference circuit and the oscillation frequency of the measurement circuit;

[0011] S2. Calculating an actual value of the inductance in the resonant circuit of the reference circuit at the current temperature based on the circuit structure and the oscillation frequency of the reference circuit, that is, obtaining an actual value of the inductance in the resonant circuit of the measurement circuit at the current temperature;

[0012] S3. Calculate the actual value of the capacitance to be measured in the measurement circuit at the current temperature based on the circuit structure of the measurement circuit, the oscillation frequency of the measurement circuit, and the actual value of the inductance in the resonant circuit of the measurement circuit at the current temperature.

[0013] Preferably, the reference circuit includes a resonant circuit formed by connecting a C0G capacitor C31, a capacitor C21, a capacitor C11, and an inductor L11 in series in sequence; the actual inductance value L of the inductor L11 in the resonant circuit is T The calculation formula is:

[0014]

[0015] Among them, f T is the oscillation frequency of the reference circuit;

[0016] The measuring circuit includes a resonant circuit composed of a capacitor to be measured C32, a capacitor C22, a capacitor C12, and an inductor L12; the actual capacitance value C of the capacitor to be measured C32 in the resonant circuit is MThe calculation formula is:

[0017]

[0018] Among them, f M To measure the oscillation frequency of the circuit.

[0019] Preferably, in the reference circuit, one end of the C0G capacitor C31 is connected to the inductor L11, the common end of the C0G capacitor C31 and the capacitor C21 is grounded, the common end of the capacitor C21 and the capacitor C11 is connected to the emitter of the transistor Q11, the common end of the capacitor C11 and the inductor L11 is connected to the collector of the transistor Q11 and is connected to the capacitor C51, and the other end of the capacitor C51 serves as the output end to output the signal Vout1; the emitter of the transistor Q11 is connected to the resistor R31, and the other end of the resistor R31 is grounded; the collector of the transistor Q11 is connected to the inductor L21, and the other end of the inductor L21 is connected to VCC; the base of the transistor Q11 is connected to the resistor R11, the resistor R21, and the capacitor Cr1 in parallel, the other end of the resistor R11 is connected to VCC, and the other ends of the resistor R21 and the capacitor Cr1 are both grounded.

[0020] Preferably, one end of the capacitor C32 to be measured in the measuring circuit is connected to the inductor L12, the common end of the capacitor C32 to be measured and the capacitor C22 is grounded, the common end of the capacitor C22 and the capacitor C12 is connected to the emitter of the transistor Q12, the common end of the capacitor C12 and the inductor L12 is connected to the collector of the transistor Q12 and is connected to the capacitor C52, and the other end of the capacitor C52 is used as the output end to output the signal Vout2; the emitter of the transistor Q12 is connected to the resistor R32, and the other end of the resistor R32 is grounded; the collector of the transistor Q12 is connected to the inductor L22, and the other end of the inductor L22 is connected to VCC; the base of the transistor Q12 is connected to the resistor R12, the resistor R22, and the capacitor Cr2 in parallel, the other end of the resistor R12 is connected to VCC, and the other ends of the resistor R22 and the capacitor Cr2 are both grounded.

[0021] Preferably, the specifications and batches of corresponding circuit components in the reference circuit and the measurement circuit are the same.

[0022] Preferably, the reference circuit and the measurement circuit are symmetrically printed on the top and bottom layers of the circuit board to form a printed circuit board, which is installed in a metal housing. The printed circuit board and the metal housing are connected by an AIN ceramic sheet, and thermally conductive epoxy resin is also filled between the printed circuit board and the metal housing.

[0023] Another object of the present invention is to provide a capacitance measurement system based on a dual LC resonant circuit, for implementing the above-mentioned capacitance measurement method based on a dual LC resonant circuit. The capacitance measurement system based on the dual LC resonant circuit includes a DC power supply module, an MCU, and a measurement module. The DC power supply module is electrically connected to the MCU and the measurement module respectively. The measurement module includes a reference circuit and a measurement circuit. The MCU is used to respectively collect the resonant frequency of the reference circuit and the resonant frequency of the measurement circuit in the measurement module. The capacitance to be measured in the measurement circuit is formed between the metal nozzle and the target plate during the laser cutting process.

[0024] Based on the circuit structure of the reference circuit and the resonant frequency of the reference circuit collected by the MCU, the actual value of the inductance in the resonant circuit of the reference circuit at the current temperature is calculated, that is, the actual value of the inductance in the resonant circuit of the measurement circuit at the current temperature is obtained;

[0025] Based on the circuit structure of the measurement circuit, the resonant frequency of the measurement circuit collected by the MCU, and the actual value of the inductance in the resonant circuit of the measurement circuit at the current temperature, the actual value of the capacitance to be measured in the resonant circuit of the measurement circuit at the current temperature is calculated.

[0026] The beneficial effects of the present invention are as follows: This capacitance measurement method and measurement system based on a dual LC resonant circuit utilizes a symmetrical structure and consistent component specifications. The reference circuit and measurement circuit are placed on the top and bottom layers of a circuit board, allowing them to operate at the same ambient temperature. By measuring the resonant frequency of the reference circuit, the actual value of the inductor is accurately calculated. The capacitance value is then inferred based on the frequency of the measurement circuit. This effectively avoids the problem of cumulative amplification of measurement errors caused by inductor temperature drift, significantly improving the temperature stability and accuracy of capacitance measurement.

[0027] Furthermore, a C0G capacitor is used as a reference standard capacitor in the reference circuit. Its low temperature drift characteristic ensures that the capacitance value of the reference oscillation circuit is constant and can be used as a stable benchmark. The inductors, resistors, transistors and other components of the two circuits are selected from the same batch and have the same parameters to ensure highly consistent performance of the two circuits, so that the impact of temperature changes on the inductance value can be equivalently transmitted to the measurement circuit.

[0028] Furthermore, the application of this technology in measuring the capacitance between the metal nozzle and the target plate during the laser cutting process can significantly improve the response accuracy and robustness of the cutting gun height adjustment system, thereby improving cutting accuracy, reducing accidental injuries and nozzle loss, and improving material processing yield. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0030] Figure 1 It is a structural schematic diagram of the laser cutting system involved in the present invention;

[0031] Figure 2 is a circuit diagram of the present invention;

[0032] Figure 3 is a packaging diagram of a circuit board of the present invention;

[0033] Figure 4 It is a system block diagram of the present invention.

[0034] The following are marked in the figure: 1. Laser cutting gun; 2. Metal nozzle; 3. Target plate; 4. Printed circuit board; 5. Metal casing; 6. AIN ceramic sheet. DETAILED DESCRIPTION

[0035] like Figure 1 As shown, the laser cutting system includes a laser cutting gun 1, a metal nozzle 2, and a target plate 3. The bottom of the laser cutting gun 1 is connected to the metal nozzle 2 for cutting the target plate 3. To improve cutting quality, it is necessary to ensure that the relative distance between the metal nozzle 2 and the target plate 3 is within a preset range.

[0036] During the laser cutting process, the relative positions of the metal nozzle 2 and the target plate 3 are as follows: Figure 1 As shown, a capacitor structure is formed between the metal nozzle 2 and the target plate 3. By measuring the capacitance value, the relative distance between the metal nozzle 2 and the target plate 3 can be indirectly obtained, so that the corresponding height adjustment operation can ensure that the relative distance between the metal nozzle 2 and the target plate 3 is within a preset range.

[0037] Example 1

[0038] A capacitance measurement method based on a dual LC resonant circuit involves placing a reference circuit and a measurement circuit on the top and bottom of a circuit board, placing them in the same environment. Both the reference circuit and the measurement circuit are LC resonant circuits, with identical circuit structures and identical circuit components in corresponding locations.

[0039] like Figure 2 As shown, the reference circuit includes a resonant circuit composed of a C0G capacitor C31, a capacitor C21, a capacitor C11, and an inductor L11. It should be noted that the C0G capacitor C31 has a low temperature drift characteristic, and its temperature drift can be ignored.

[0040] Among them, one end of the C0G capacitor C31 is connected to the inductor L11, the common end of the C0G capacitor C31 and the capacitor C21 is grounded, the common end of the capacitor C21 and the capacitor C11 is connected to the emitter of the transistor Q11, the common end of the capacitor C11 and the inductor L11 is connected to the collector of the transistor Q11 and connected to the capacitor C51, and the other end of the capacitor C51 serves as the output end to output the signal Vout1.

[0041] Specifically, the emitter of the transistor Q11 is connected to the resistor R31, and the other end of the resistor R31 is grounded; the collector of the transistor Q11 is connected to the inductor L21, and the other end of the inductor L21 is connected to VCC; the base of the transistor Q11 is connected to the resistor R11, the resistor R21, and the capacitor Cr1 in parallel, and the other end of the resistor R11 is connected to VCC, and the other ends of the resistor R21 and the capacitor Cr1 are both grounded.

[0042] The measurement circuit and the reference circuit have the same structure, both are LC resonant circuits, and the circuit components at corresponding positions have the same specifications and batches. The difference is that the capacitor to be measured C32 is located at the position of the C0G capacitor C31 in the measurement circuit corresponding to the reference circuit.

[0043] like Figure 2 As shown, the measurement circuit includes a resonant circuit consisting of a measured capacitor C32, a capacitor C22, a capacitor C12, and an inductor L12, wherein one end of the measured capacitor C32 is connected to the inductor L12, the common end of the measured capacitor C32 and the capacitor C22 is grounded, the common end of the capacitor C22 and the capacitor C12 is connected to the emitter of the transistor Q12, the common end of the capacitor C12 and the inductor L12 is connected to the collector of the transistor Q12 and is connected to the capacitor C52, and the other end of the capacitor C52 serves as an output end to output a signal Vout2.

[0044] Specifically, the emitter of the transistor Q12 is connected to the resistor R32, and the other end of the resistor R32 is grounded; the collector of the transistor Q12 is connected to the inductor L22, and the other end of the inductor L22 is connected to VCC; the base of the transistor Q12 is connected to the resistor R12, the resistor R22, and the capacitor Cr2 in parallel, the other end of the resistor R12 is connected to VCC, and the other ends of the resistor R22 and the capacitor Cr2 are both grounded.

[0045] Specifically, a dual LC resonant circuit is formed based on the LC resonant circuit of the reference circuit and the measurement circuit, and the measurement process of the capacitance to be measured in the measurement circuit includes the following steps:

[0046] S1. Measure the oscillation frequency f of the reference circuit T , measure the oscillation frequency f of the circuit M .

[0047] S2. Circuit structure based on reference circuit and measured oscillation frequency f T , calculate the actual inductance value L of the inductor L11 in the reference circuit at the current temperature T Since the reference circuit and the measurement circuit have the same circuit structure and use circuit components of the same specifications and batches, the actual value of inductor L12 in the measurement circuit at the current temperature is equivalent to the actual value of inductor L11 at the current temperature calculated by the reference circuit.

[0048] Specifically, based on the circuit structure of the reference circuit, we can know that:

[0049]

[0050] Formula (2) can be obtained by transforming formula (1):

[0051]

[0052] S3, based on the circuit structure of the measurement circuit, the measured oscillation frequency f M , and the actual inductance value L of the inductor L12 in the measurement circuit at the current temperature T Calculate the actual capacitance value C of the inductor C32 to be tested at the current temperature M , the calculation formula is as follows:

[0053]

[0054] According to the above calculation process, the actual capacitance value C of the inductor C32 to be measured at the current temperature is obtained. M , which can eliminate the temperature drift of the inductor L12 in the circuit, so that the actual capacitance value C of the inductor C32 to be measured is M Closer to the true value.

[0055] like Figure 3 As shown, to ensure that the working environment of the reference circuit and the measurement circuit is consistent, the reference circuit and the measurement circuit are printed symmetrically on the top and bottom layers of a circuit board to form a printed circuit board 4. The printed circuit board 4 is then installed in a metal housing 5. The printed circuit board 4 and the metal housing 5 are connected via an AlN ceramic sheet 6. Thermally conductive epoxy resin is filled between the printed circuit board 4 and the metal housing 5.

[0056] Example 2

[0057] like Figure 4 As shown, a capacitance measurement system based on a dual LC resonant circuit is used to implement the capacitance measurement method based on a dual LC resonant circuit as described in Example 1, thereby being used to measure the capacitance during laser cutting, such as Figure 1 The capacitance value of the capacitor structure formed between the metal nozzle 2 and the target plate 3 is shown.

[0058] The capacitance measurement system based on the dual LC resonant circuit includes a DC power supply module, an MCU, and a measurement module. The measurement module includes a reference circuit and a measurement circuit. The reference circuit and the measurement circuit are respectively arranged on the top and bottom of the same circuit board, so that the reference circuit and the measurement circuit are in the same environment.

[0059] In addition, the DC power module is used to power the MCU and measurement module. The MCU includes two frequency acquisition ports, one for acquiring the resonant frequency of the measurement circuit and the other for acquiring the resonant frequency of the reference circuit. Specifically, the two frequency acquisition ports of the MCU acquire the waveform frequencies of signals Vout1 and Vout2, respectively, to obtain the resonant frequencies of the reference circuit and the measurement circuit.

[0060] Specifically, both the reference circuit and the measurement circuit are LC resonant circuits with identical circuit structures. The circuit components in the corresponding positions are of the same specifications and batches. It's important to note that the capacitor in the reference circuit corresponding to the capacitor to be measured in the measurement circuit uses a C0G capacitor. C0G capacitor C31 has a low temperature drift characteristic, and its temperature drift is negligible. Therefore, the temperature drift in the reference circuit primarily comes from the inductance of the resonant circuit.

[0061] Based on the structure of the LC resonant circuit, a reference circuit and a measurement circuit are designed to form a dual LC resonant circuit. For the reference circuit, the actual inductance value of the reference circuit's resonant loop at the current temperature can be calculated based on the acquired resonant frequency and the principle of resonant frequency calculation.

[0062] For the measurement circuit, since its circuit structure, circuit component specifications, and batches are identical to those of the reference circuit, the actual value of the inductance in the resonant circuit of the measurement circuit is the same as the actual value of the inductance in the resonant circuit calculated based on the reference circuit. Based on the circuit structure of the measurement circuit, the actual value of the capacitance to be measured can be calculated using the collected resonant frequency and the calculated actual value of the inductance in the resonant circuit.

[0063] The capacitance measurement system based on the dual LC resonant circuit effectively eliminates the influence of temperature drift of the inductance in the resonant circuit, and the actual value of the capacitance to be measured obtained by calculation is closer to the true value.

[0064] In laser cutting, accurately measuring the capacitance value formed between the metal nozzle 2 and the target plate 3 can effectively improve the accuracy of adjusting the height of the laser cutting gun 1, thereby improving the cutting effect.

[0065] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art will be able to modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein with equivalents. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A capacitance measurement method based on a dual LC resonant circuit, characterized in that: The reference circuit and the measurement circuit are located at the top and bottom of the same circuit board so that the reference circuit and the measurement circuit are in the same environment. The reference circuit and the measurement circuit are LC resonant circuits with the same structure. The measurement circuit includes a capacitor to be measured, and the circuit element corresponding to the capacitor to be measured in the reference circuit is a C0G capacitor. The method for measuring the capacitance value of the capacitor to be measured specifically includes the following steps: S1, collecting the oscillation frequency of the reference circuit and the oscillation frequency of the measurement circuit; S2. Calculating an actual value of the inductance in the resonant circuit of the reference circuit at the current temperature based on the circuit structure and the oscillation frequency of the reference circuit, that is, obtaining an actual value of the inductance in the resonant circuit of the measurement circuit at the current temperature; S3. Calculate the actual value of the capacitance to be measured in the measurement circuit at the current temperature based on the circuit structure of the measurement circuit, the oscillation frequency of the measurement circuit, and the actual value of the inductance in the resonant circuit of the measurement circuit at the current temperature.

2. The capacitance measurement method based on the dual LC resonant circuit according to claim 1, characterized in that: The reference circuit includes a resonant circuit composed of a C0G capacitor C31, a capacitor C21, a capacitor C11, and an inductor L11; the actual inductance value L of the inductor L11 in the resonant circuit is T The calculation formula is: Among them, f T is the oscillation frequency of the reference circuit; The measuring circuit includes a resonant circuit composed of a capacitor to be measured C32, a capacitor C22, a capacitor C12, and an inductor L12; the actual capacitance value C of the capacitor to be measured C32 in the resonant circuit is M The calculation formula is: Among them, f M To measure the oscillation frequency of the circuit.

3. The capacitance measurement method based on the dual LC resonant circuit according to claim 2, characterized in that: In the reference circuit, one end of the C0G capacitor C31 is connected to the inductor L11, the common end of the C0G capacitor C31 and the capacitor C21 is grounded, the common end of the capacitor C21 and the capacitor C11 is connected to the emitter of the transistor Q11, the common end of the capacitor C11 and the inductor L11 is connected to the collector of the transistor Q11 and connected to the capacitor C51, and the other end of the capacitor C51 serves as an output end to output the signal Vout1; The emitter of the transistor Q11 is connected to a resistor R31, and the other end of the resistor R31 is grounded; the collector of the transistor Q11 is connected to an inductor L21, and the other end of the inductor L21 is connected to VCC; the base of the transistor Q11 is connected to a resistor R11, a resistor R21, and a capacitor Cr1 in parallel, and the other end of the resistor R11 is connected to VCC, and the other ends of the resistor R21 and the capacitor Cr1 are both grounded.

4. The capacitance measurement method based on the dual LC resonant circuit according to claim 2, characterized in that: One end of the capacitor C32 to be measured in the measuring circuit is connected to the inductor L12, the common end of the capacitor C32 to be measured and the capacitor C22 is grounded, the common end of the capacitor C22 and the capacitor C12 is connected to the emitter of the transistor Q12, the common end of the capacitor C12 and the inductor L12 is connected to the collector of the transistor Q12 and connected to the capacitor C52, and the other end of the capacitor C52 serves as an output end to output a signal Vout2; The emitter of the transistor Q12 is connected to a resistor R32, the other end of which is grounded; the collector of the transistor Q12 is connected to an inductor L22, the other end of which is connected to VCC; the base of the transistor Q12 is connected to a resistor R12, a resistor R22, and a capacitor Cr2 in parallel, the other end of the resistor R12 is connected to VCC, and the other ends of the resistor R22 and the capacitor Cr2 are both grounded.

5. The capacitance measurement method based on the dual LC resonant circuit according to claim 1, characterized in that: The specifications and batches of corresponding circuit components in the reference circuit and the measurement circuit are the same.

6. The capacitance measurement method based on a dual LC resonant circuit according to claim 1, characterized in that: The reference circuit and the measurement circuit are symmetrically printed on the top layer and the bottom layer of the circuit board to form a printed circuit board (4). The printed circuit board (4) is installed in a metal housing (5). The printed circuit board (4) and the metal housing (5) are connected via an AIN ceramic sheet (6). Thermally conductive epoxy resin is also filled between the printed circuit board (4) and the metal housing (5).

7. A capacitance measurement system based on a dual LC resonant circuit, characterized in that: Used to implement the capacitance measurement method based on a dual LC resonant circuit as described in any one of claims 1 to 6, the capacitance measurement system based on the dual LC resonant circuit includes a DC power supply module, an MCU, and a measurement module, the DC power supply module is electrically connected to the MCU and the measurement module respectively, the measurement module includes a reference circuit and a measurement circuit, the MCU is used to respectively collect the resonant frequency of the reference circuit and the resonant frequency of the measurement circuit in the measurement module; the capacitance to be measured in the measurement circuit is formed between a metal nozzle (2) and a target plate (3) during the laser cutting process; Based on the circuit structure of the reference circuit and the resonant frequency of the reference circuit collected by the MCU, the actual value of the inductance in the resonant circuit of the reference circuit at the current temperature is calculated, that is, the actual value of the inductance in the resonant circuit of the measurement circuit at the current temperature is obtained; Based on the circuit structure of the measurement circuit, the resonant frequency of the measurement circuit collected by the MCU, and the actual value of the inductance in the resonant circuit of the measurement circuit at the current temperature, the actual value of the capacitance to be measured in the resonant circuit of the measurement circuit at the current temperature is calculated.

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