Hard strap voltage monitoring device and method

Abstract

The invention discloses a hard strap voltage monitoring device and method, and relates to the field of power grid hard strap voltage monitoring, the device is provided with a first metal plate, a second metal plate and a third metal plate which are arranged in parallel in principle, the first metal plate is connected with an object to be measured or the object to be measured is regarded as the first metal plate in actual use; the second metal plate is grounded; the other end of the capacitor is connected with one end of the first resistor and the grid electrode of the field effect transistor. The drain electrode of the field effect transistor is connected with one end of the second resistor, and the source electrode and the other end of the first resistor are grounded together. The device drives the second metal plate to do sine regular motion along the vertical direction through a sine signal, thereby changing the voltage of the third metal plate, calculating the amplitude of the voltage to be measured by using the peak-to-peak value of the voltage, judging the polarity of the voltage by combining the phase difference, being only used for accurate measurement of the voltage, not needing gear switching, and avoiding tripping accidents caused by wrong gear selection of a universal meter. And the non-contact design is adopted, so that the voltage measurement safety is improved.

Description

Technical Field

[0001] This application relates to the field of voltage monitoring using hard-plate voltage monitoring in power grids, and in particular to a device and method for voltage monitoring using hard-plate voltage monitoring. Background Technology

[0002] In smart grids, the activation and deactivation status of hard-plate circuit breakers is crucial. Before activation according to regulations, the voltage across its terminals to ground must be measured. However, the traditional method of manual measurement using a multimeter is prone to causing tripping accidents in the control circuit due to incorrect range settings, resulting in low safety. For example, when measuring voltage while the circuit is powered on, setting the multimeter to the current range (mA / A) is equivalent to a short circuit, which will instantly blow the fuse or meter and cause the control circuit to trip. In addition, manual measurement is time-consuming, labor-intensive, and prone to errors. Therefore, it is necessary to use a non-invasive voltage monitoring device to monitor the voltage of the hard-plate circuit breaker in real time. Summary of the Invention

[0003] The purpose of this application is to develop a non-invasive hard plate voltage monitoring device and method to solve the problem that the traditional manual measurement method using a multimeter is prone to tripping accidents caused by incorrect range selection in the control circuit.

[0004] To achieve the above objectives, this application provides the following solution.

[0005] In a first aspect, this application provides a hard plate voltage monitoring device, comprising: a first metal plate and a second metal plate that are parallel to each other; a third metal plate is disposed between the first metal plate and the second metal plate; wherein the length of the first metal plate and the length of the second metal plate are greater than the length of the third metal plate, and the second metal plate moves in a sinusoidal manner along the vertical direction.

[0006] The third metal plate is connected to one end of the capacitor; the other end of the capacitor is connected to one end of the first resistor and the gate of the field-effect transistor; the drain of the field-effect transistor is connected to one end of the second resistor; the source of the field-effect transistor is grounded to the other end of the first resistor; and the other end of the second resistor is connected to the positive terminal of the power supply.

[0007] The first metal plate is connected to the voltage input terminal of the hard plate, and the second metal plate is grounded.

[0008] In one embodiment, the peak-to-peak value of the voltage between the drain and source of the field-effect transistor is proportional to the voltage on the first metal plate; the voltage between the drain and source of the field-effect transistor is proportional to the voltage variation on the third metal plate.

[0009] In one embodiment, the electric field between the first metal plate and the second metal plate is proportional to the voltage difference between the first metal plate and the second metal plate, and the electric field is inversely proportional to the first distance.

[0010] In one embodiment, when the first metal plate is the conductor to be tested, the area of ​​the second metal plate and the third metal plate facing each other is on the same order of magnitude as the cross-sectional area of ​​the conductor to be tested.

[0011] In one embodiment, when the second metal plate is a metal cantilever beam, the third metal plate is a solder pad; the solder pad is disposed on the PCB board; the metal cantilever beam is driven to vibrate by a vibration structure in a magnetoelectric or piezoelectric manner.

[0012] In one embodiment, when the metal cantilever beam is driven to vibrate in a magnetoelectric manner, the vibration structure specifically includes: a metal cantilever beam, a solder pad, a permanent magnet, an electromagnet, and an electromagnet drive circuit.

[0013] The permanent magnet is fixed to the end of the metal cantilever beam; the permanent magnet and the electromagnet are coaxially arranged in the vertical direction; the two poles of the electromagnet are connected to the PCB board through wires; the electromagnet is fixed to the electromagnet drive circuit by bottom screws; the electromagnet generates an alternating magnetic field through the alternating current provided by the electromagnet drive circuit, which drives the permanent magnet to drive the metal cantilever beam to vibrate up and down in a sinusoidal pattern.

[0014] In one embodiment, when the metal cantilever beam is vibrated by piezoelectric force, the vibration structure specifically includes: the metal cantilever beam, pads, piezoelectric sheet, and piezoelectric sheet driving circuit.

[0015] The piezoelectric element is fixed to the metal cantilever beam with conductive adhesive. The piezoelectric element vibrates through the AC voltage signal provided by the piezoelectric element driving circuit, causing the metal cantilever beam to vibrate up and down in a sinusoidal pattern.

[0016] Secondly, this application provides a method for monitoring the voltage of a hard pressure plate, which is applied to a hard pressure plate voltage monitoring device, and the method includes...

[0017] A voltage to be measured is applied to a first metal plate and a second metal plate. A first distance between the first and second metal plates, a second distance between the first and third metal plates, and the voltage on the first metal plate are obtained. The second metal plate is driven to move sinusoidally in a vertical direction using a sinusoidal signal. When the first distance, the second distance, and the change in the movement of the second metal plate remain constant, the voltage on the first metal plate is determined based on the peak-to-peak value of the voltage changing on the third metal plate; the voltage on the first metal plate is the voltage to be measured.

[0018] In one embodiment, the voltage value of the voltage to be measured is determined based on the peak-to-peak value of the changing voltage, and then the method further includes: determining the polarity of the voltage to be measured based on the measured phase difference between the changing voltage and the sinusoidal driving signal.

[0019] In one embodiment, determining the polarity of the voltage to be measured based on the measured phase difference between the changing voltage and the sinusoidal driving signal specifically includes:

[0020] The phase difference between the changing voltage and the sinusoidal drive signal is taken as the measured phase difference. Before leaving the factory, the same positive (negative) voltage is measured using different sensors to determine the maximum and minimum phase differences for positive (negative) voltages. Based on the maximum and minimum phase differences for positive (negative) voltages, the phase difference range for positive (negative) voltages is determined. The lower limit of the phase difference range for positive (negative) voltages is the minimum phase difference, and the upper limit of the phase difference range for positive (negative) voltages is the maximum phase difference. These upper and lower limits are written into the sensor. When the measured phase difference is within the phase difference range for positive voltages, the polarity of the voltage to be measured is determined to be positive. When the measured phase difference is within the phase difference range for both positive and negative voltages, the polarity of the voltage to be measured is determined to be negative.

[0021] Based on the specific embodiments provided in this application, the following technical effects are disclosed.

[0022] This application provides a voltage monitoring device and method for a hard platen. A first metal plate and a second metal plate are arranged parallel to each other. The second metal plate moves sinusoidally in a vertical direction. A third metal plate is connected to one end of a capacitor, the other end of which is simultaneously connected to one end of a first resistor and the gate of a field-effect transistor (FET). The drain of the FET is connected to one end of the second resistor, and its source and the other end of the first resistor are grounded together. The other end of the second resistor is connected to the positive terminal of a power supply. The first metal plate is connected to the voltage input terminal of the hard platen, and the second metal plate is connected to the voltage output terminal of the hard platen. This application drives the second metal plate to move by applying a sinusoidal signal, changing the voltage of the third metal plate. The amplitude of the voltage to be measured is calculated using the peak-to-peak value of the changing voltage of the third metal plate, and the phase difference between the sinusoidal driving signal and the changing voltage is used to determine V. S The polarity of the voltage is determined to achieve accurate voltage measurement. The hard plate voltage monitoring device of this application is only used for voltage measurement, and will not cause problems caused by selecting the wrong current range when measuring voltage. It effectively solves the problem of tripping accidents caused by the control circuit due to the easy selection of the wrong range when using a multimeter manually. The non-contact voltage monitoring device can measure the voltage of the hard plate conductor through the conductor insulation, thus improving the safety of voltage measurement. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a parallel plate model diagram of a hard plate voltage monitoring device provided in one embodiment of this application.

[0025] Figure 2 This is a schematic diagram of an actual measurement model of a hard plate voltage monitoring device provided in an embodiment of this application.

[0026] Figure 3 This is a schematic diagram of a magnetoelectric driven cantilever beam provided in one embodiment of this application.

[0027] Figure 4 This is a schematic diagram of a piezoelectric driven cantilever beam provided in an embodiment of this application.

[0028] Figure 5 This is a schematic diagram showing the positive polarity of the voltage to be measured, provided as an embodiment of this application.

[0029] Figure 6 This is a schematic diagram showing the negative polarity of the voltage to be measured according to an embodiment of this application.

[0030] Figure 7 This is a circuit diagram of an electromagnet drive provided in an embodiment of this application.

[0031] Figure 8 This is a piezoelectric element driving circuit diagram provided in one embodiment of this application.

[0032] Reference numerals in the attached figures: 1. First metal plate; 2. Second metal plate; 3. Third metal plate; 4. Capacitor; 5. First resistor; 6. Field-effect transistor; 7. Second resistor; 8. Wire to be tested; 9. Pad; 10. Metal cantilever beam; 11. Permanent magnet; 12. Electromagnet; 13. Piezoelectric element; 14. Electromagnet drive circuit; 15. Piezoelectric element drive circuit. Detailed Implementation

[0033] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0034] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0035] The first aspect, such as Figure 1 As shown, this application provides a hard plate voltage monitoring device, including: a first metal plate 1, a second metal plate 2 and a third metal plate 3 that are parallel to each other; the third metal plate 3 is disposed between the first metal plate 1 and the second metal plate 2; wherein, the length of the first metal plate 1 and the length of the second metal plate 2 are greater than the length of the third metal plate 3, and the second metal plate 2 moves in a sinusoidal manner along the vertical direction.

[0036] The third metal plate 3 is connected to one end of the capacitor 4; the other end of the capacitor 4 is connected to one end of the first resistor 5 and the gate of the field-effect transistor 6; the drain of the field-effect transistor 6 is connected to one end of the second resistor 7; the source of the field-effect transistor 6 is grounded to the other end of the first resistor 5; the other end of the second resistor 7 is connected to the positive power supply V. dd The first metal plate 1 is connected to the voltage input terminal of the hard pressure plate, and the second metal plate 2 is connected to the voltage output terminal of the hard pressure plate.

[0037] Among them, the voltage U between the drain and source of the field-effect transistor 6 O The peak-to-peak value is related to the voltage V on the first metal plate 1 S Proportional; the voltage U between the drain and source of the field-effect transistor is... O The voltage on the third metal plate is the changed voltage. The electric field between the first metal plate 1 and the second metal plate 2 is proportional to the voltage difference between them, and the electric field is inversely proportional to the first distance D. When D1, D, and d remain constant, the magnitude of VS can be calculated by measuring the peak-to-peak value of Uo after signal amplification and conditioning by an operational amplifier.

[0038] In an exemplary embodiment, a voltage V is applied across two parallel first metal plates 1 and second metal plates 2. S The voltage of the first metal plate 1 is V. S If the voltage of the second metal plate 2 is 0V, then an electric field E exists between the two metal plates. The strength of the electric field E is related to the voltage difference V. S The electric field E is directly proportional to the first distance D between the two metal plates, as shown in formula (1).

[0039] (1) The third metal plate 3 is placed in the electric field E. The distance between the third metal plate 3 and the first metal plate 1 is D1. The voltage U3 on the third metal plate 3 (with the voltage of the second metal plate 2 as 0V as a reference) is as shown in formula (2).

[0040] (2) The calculation formula for the voltage of the third metal plate 3 is converted from formula (1) and formula (2) into the relationship between the voltage of the third metal plate 3, the voltage Vs of the first metal plate 1, and the distance between the two metal plates, as shown in formula (3).

[0041] (3) If the distance D1 between the first metal plate 1 and the metal plate 3 remains constant, and the second metal plate 2 is driven by a sinusoidal signal, ensuring that the second metal plate 2 moves at a distance D1... The voltage of the third metal plate 3 after the second metal plate 2 moves up and down according to the law of sin(ωt) is as shown in formula (3).

[0042] (4) Where d is the amplitude of the change, and ω is the angular frequency.

[0043] From formula (4), it can be seen that the voltage U on the third metal plate 3 changes sinusoidally with the up-and-down movement of the second metal plate 2. And when V... S When >0, d As sin(ωt) increases, U will increase, and d As sin(ωt) decreases, U will decrease, and at this time, the phase d of U will... sin(ωt) is the same; when V S When <0, d As sin(ωt) increases, U will decrease, d As sin(ωt) decreases, U will increase, and at this time, the phase d of U will increase. sin(ωt) are 180 degrees apart, and V is determined based on the phase difference. S The polarity of.

[0044] Because the downward movement of the second metal plate 2 causes a change in the voltage of the third metal plate 3, when the amplitude d of the change in the second metal plate 2 remains constant, the peak-to-peak value of the voltage change u on the third metal plate 3 is different from the voltage V on the first metal plate 1. S Proportional. Because V S Since it remains unchanged, the invariant term V in formula (4) is... S By removing the voltage change of the third metal plate 3, we can obtain the voltage change of the third metal plate 3, as shown in formula (5).

[0045] u=V S D1 / (D+d sin(ωt)) (5) In actual non-contact measurement of the voltage of the conductor of the hard plate, such as Figure 2 As shown, the first metal plate 1 is replaced with the wire to be tested 8. The facing areas of the second metal plate 2 and the third metal plate 3 are on the same order of magnitude as the cross-sectional area of ​​the wire to be tested 8. Since the capacitance is related to its facing area, during installation, the wire to be tested 8, the third metal plate 3, and the first metal plate 1 should be kept as parallel as possible. This can be regarded as the above-mentioned three parallel metal plate model for calculating the voltage V of the wire to be tested. S It is important to ensure that the first resistance 5 between the gate of the N-channel junction field-effect transistor 6 and ground is sufficiently large (generally above 10MΩ) to reduce the leakage current between the third metal plate 3 and ground, thereby reducing the impact on the test results of the voltage under test.

[0046] In one exemplary embodiment, such as Figure 3 As shown, when the second metal plate 2 is a metal cantilever beam 10, the third metal plate 3 is a solder pad 9; the solder pad 9 is disposed on the PCB board; the metal cantilever beam 10 is driven to vibrate by a vibration structure in a magnetoelectric or piezoelectric manner.

[0047] When the metal cantilever beam 10 is driven to vibrate by a magnetoelectric method, the vibration structure specifically includes: the metal cantilever beam 10, pads 9, permanent magnet 11, electromagnet 12, and electromagnet drive circuit 14; the metal cantilever beam 10 is grounded; the permanent magnet 11 is fixed to the end of the metal cantilever beam 10 and has no electrical connection with other components; the permanent magnet 11 and the electromagnet 12 are coaxially arranged in the vertical direction; the electromagnet 12 is first fixed to the PCB board by screws through mechanical mounting holes, and the electrical connection of the electromagnet is also on the PCB board. The two poles of the electromagnet 12 are connected to the PCB board through wires, and the electromagnet 12 is fixed to the electromagnet drive circuit 14 by bottom screws; the electromagnet 12 generates an alternating magnetic field through the alternating current provided by the electromagnet drive circuit 14, driving the permanent magnet 11 to drive the metal cantilever beam 10 to vibrate up and down in a sinusoidal pattern.

[0048] like Figure 4 As shown, when the metal cantilever beam 10 is driven to vibrate by a piezoelectric actuator, the vibration structure specifically includes: the metal cantilever beam 10, the pad 9, the piezoelectric element 13, and the piezoelectric element driving circuit 15; the piezoelectric element 13 is fixed to the metal cantilever beam 10 by conductive adhesive, and the piezoelectric element 13 vibrates by the AC voltage signal provided by the piezoelectric element driving circuit 15, driving the metal cantilever beam 10 to vibrate up and down in a sinusoidal pattern.

[0049] Secondly, the hard plate voltage monitoring method provided in this application embodiment is applied to a hard plate voltage monitoring device, specifically including...

[0050] Step 1: Apply the voltage to be measured to the first metal plate 1 and the second metal plate 2, and obtain the first distance D from the first metal plate 1 to the second metal plate 2, the second distance D1 from the first metal plate 1 to the third metal plate 3, and the voltage on the first metal plate 1, which is the voltage to be measured Vs.

[0051] Step 2: Use a sinusoidal signal to drive the second metal plate 2 to move in a sinusoidal pattern along the vertical direction, and determine the voltage U3 on the third metal plate 3 based on the voltage Vs on the first metal plate 1 and the second distance D1.

[0052] Step 3: Determine the changing voltage u on the third metal plate 3 based on the amount of movement of the second metal plate 2.

[0053] Step 4: Determine the voltage value of the voltage to be measured based on the peak-to-peak value of the changing voltage.

[0054] Among them, such as Figures 5-6 As shown, step four determines the voltage value of the voltage to be measured based on the peak-to-peak value of the changing voltage. This step further includes: determining the polarity of the voltage to be measured based on the measured phase difference between the changing voltage and the sinusoidal drive signal. Specifically, this includes: using the phase difference between the peak-to-peak value of the changing voltage and the sinusoidal signal as the measured phase difference; measuring the same positive (negative) voltage to be measured using different sensors before leaving the factory to determine the maximum and minimum phase differences for positive (negative) voltages; determining the phase difference range for positive (negative) voltages based on the maximum and minimum phase differences; the lower limit of the phase difference range for positive (negative) voltages is the minimum phase difference, and the upper limit of the phase difference range for positive (negative) voltages is the maximum phase difference; these upper and lower limits are written into the sensor; when the measured phase difference is within the phase difference range for positive voltages, the polarity of the voltage to be measured is determined to be positive; when the measured phase difference is within the phase difference range for both positive and negative voltages, the polarity of the voltage to be measured is determined to be negative.

[0055] The above analysis shows that the peak-to-peak value of the drain output AC voltage U of field-effect transistor 6 is... O With the voltage V of the conductor under test SThe magnitude of the voltage is directly proportional to the following factors: the first distance D from the conductor 8 to the second metal plate 2; the second distance D1 from the conductor 8 to the third metal plate 3; and the vibration amplitude d of the second metal plate 2. In actual production and installation, it is difficult to guarantee the consistency of D, D1, and d for each hard-plate voltage monitoring sensor, and measuring these parameters for each sensor would be extremely labor-intensive and impractical. Therefore, a method of calibrating by measuring a known voltage is adopted to enhance the accuracy of sensor measurements and the consistency between sensors. The specific implementation plan in practical applications is as follows.

[0056] U O It is the voltage amplified from the voltage on the third metal plate 3, let U O The peak value is X, Y=V S Then Y=K X+B, where K and B are constants; given two known voltages Y1 and Y2, measure and record U using a sensor. O The peak values ​​X1 and X2 are used to calculate K and B through (X1, Y1) and (X2, Y2), and stored in the sensor; U is then measured using the sensor. O The peak value X is obtained through Y=K X+B calculates the magnitude of the voltage Y to be measured.

[0057] Both piezoelectric and magnetoelectric driven cantilever beams are driven by sinusoidal signals, and the voltage V to be measured is used to drive them. S The sinusoidal drive signal and U received by the metal cantilever beam 10 under two polarities O The phase difference is calculated, and then the range of the phase difference for positive and negative polarities is determined by combining the test results. This range is then written into the code for use in actual testing to determine the voltage V to be measured. S The polarity of.

[0058] Electromagnet drive circuit such as Figure 7As shown, the DAC pin of the microcontroller outputs a voltage that varies sinusoidally. This voltage is filtered out by a low-pass filter consisting of resistor 16 and capacitor 26. After being divided by resistors 17 and 25, the voltage is input to the positive input terminal of operational amplifier 18. The output terminal of operational amplifier 18 is connected to resistor 24 and then to the base of NPN transistor 22. The collector of transistor 22 is connected to electromagnet 21 and then to the cathode of diode 20. The anode of diode 20 is connected to the power supply VDD. To eliminate the reverse current generated by electromagnet 21, diode 19 is connected in parallel across it. The emitter of transistor 22 is connected to ground via resistor 23. In addition, the emitter of transistor 22 is also connected to the inverting input terminal of operational amplifier 18. Operational amplifier 18 operates in a deep negative feedback state, so the voltage at its inverting input is equal to the voltage at its non-inverting input. Since the inverting input of op-amp 18 is connected to the emitter of transistor 22, the emitter voltage of transistor 22 is also equal to the voltage at the non-inverting input of op-amp 18. The current flowing through resistor 23 is equal to the emitter voltage of transistor 22 divided by the resistance of resistor 23. Because the current flowing into the inverting input of op-amp 18 is close to zero (virtual short), and the current flowing through the collector and emitter of transistor 22... Since the difference in magnitude is approximately equal, the current flowing through electromagnet 21 is roughly equal to the current flowing through resistor 23. Therefore, the current flowing through electromagnet 21 can be controlled by controlling the current flowing through resistor 23. With a fixed resistance value, the current flowing through resistor 23 is determined by the voltage at the positive input terminal of operational amplifier 18. Therefore, when the microcontroller's DAC pin outputs an AC voltage, a current of the same frequency will flow through electromagnet 21, and the peak-to-peak value of the current will be determined by the peak-to-peak value of the AC voltage output by the microcontroller's DAC pin.

[0059] piezoelectric drive circuit such as Figure 8 As shown, the voltage output from the microcontroller's DAC pin changes sinusoidally. First, it passes through capacitor 36 to remove the DC bias. Then, it passes through a low-pass filter composed of resistor 27 and capacitor 35 to filter out noise. After being divided by resistors 28 and 34, the voltage is input to the non-inverting input of operational amplifier 29. The inverting input of operational amplifier 29 is connected to ground via resistor 33. The inverting input of operational amplifier 29 is also connected to its output via resistor 30. The output of operational amplifier 29 is connected to piezoelectric element 32 via resistor 31. The other end of piezoelectric element 32 is grounded. The function of this circuit is to amplify the voltage output from the microcontroller's DAC pin and connect it to the piezoelectric element to drive it, thereby causing the cantilever beam to vibrate.

[0060] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0061] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. Furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A voltage monitoring device for a hard plate, characterized in that, include: A first metal plate, a second metal plate, and a third metal plate are parallel to each other; a third metal plate is disposed between the first metal plate and the second metal plate; wherein the length of the first metal plate and the length of the second metal plate are greater than the length of the third metal plate, and the second metal plate moves in a sinusoidal manner along the vertical direction; The third metal plate is connected to one end of the capacitor; the other end of the capacitor is connected to one end of the first resistor and the gate of the field-effect transistor; the drain of the field-effect transistor is connected to one end of the second resistor; the source of the field-effect transistor is grounded to the other end of the first resistor; the other end of the second resistor is connected to the positive terminal of the power supply. The first metal plate is connected to the voltage input terminal of the hard plate, and the second metal plate is grounded.

2. The hard plate voltage monitoring device according to claim 1, characterized in that, The peak-to-peak value of the voltage between the drain and source of the field-effect transistor is proportional to the voltage on the first metal plate; the voltage between the drain and source of the field-effect transistor is proportional to the voltage variation on the third metal plate.

3. The hard plate voltage monitoring device according to claim 1, characterized in that, The electric field between the first metal plate and the second metal plate is directly proportional to the voltage difference between the first metal plate and the second metal plate, and the electric field is inversely proportional to the first distance.

4. The hard plate voltage monitoring device according to claim 1, characterized in that, When the first metal plate is the conductor to be tested, the area of ​​the second metal plate and the third metal plate facing each other is on the same order of magnitude as the cross-sectional area of ​​the conductor to be tested.

5. The hard plate voltage monitoring device according to claim 1, characterized in that, When the second metal plate is a metal cantilever beam, the third metal plate is a solder pad; the solder pad is located on the PCB board; the metal cantilever beam is driven to vibrate by a vibration structure in a magnetoelectric or piezoelectric manner.

6. The hard plate voltage monitoring device according to claim 5, characterized in that, When the metal cantilever beam is driven to vibrate by magnetoelectric means, the vibration structure specifically includes: the metal cantilever beam, the pad, the permanent magnet, the electromagnet, and the electromagnet drive circuit. The permanent magnet is fixed to the end of the metal cantilever beam; the permanent magnet and the electromagnet are coaxially arranged in the vertical direction; the two poles of the electromagnet are connected to the PCB board through wires; the electromagnet is fixed to the electromagnet drive circuit by bottom screws; the electromagnet generates an alternating magnetic field through the alternating current provided by the electromagnet drive circuit, which drives the permanent magnet to drive the metal cantilever beam to vibrate up and down in a sinusoidal pattern.

7. The hard plate voltage monitoring device according to claim 5, characterized in that, When the metal cantilever beam is driven to vibrate by piezoelectricity, the vibration structure specifically includes: the metal cantilever beam, the pad, the piezoelectric element, and the piezoelectric element driving circuit. The piezoelectric element is fixed to the metal cantilever beam with conductive adhesive. The piezoelectric element vibrates through the AC voltage signal provided by the piezoelectric element driving circuit, causing the metal cantilever beam to vibrate up and down in a sinusoidal pattern.

8. A method for monitoring voltage on a hard plate, characterized in that, The hard plate voltage monitoring method is applied to a hard plate voltage monitoring device according to claims 1-7, and the hard plate voltage monitoring method includes: Obtain the first distance from the first metal plate to the second metal plate and the second distance from the first metal plate to the third metal plate; The second metal plate is driven by a sinusoidal signal to move sinusoidally along the vertical direction. When the first distance, the second distance, and the amount of movement of the second metal plate remain constant, the voltage on the first metal plate is determined based on the peak-to-peak value of the voltage change on the third metal plate; the voltage on the first metal plate is the voltage to be measured.

9. The method for monitoring voltage on a hard plate according to claim 8, characterized in that, The voltage value of the voltage to be measured is determined based on the peak-to-peak value of the changing voltage, and then the process further includes: The polarity of the voltage to be measured is determined based on the measured phase difference between the changing voltage and the sinusoidal driving signal.

10. The method for monitoring voltage on a hard plate according to claim 9, characterized in that, Determining the polarity of the voltage under test based on the measured phase difference between the changing voltage and the sinusoidal driving signal specifically includes: Before leaving the factory, the same positive voltage to be measured is measured using different sensors to determine the maximum and minimum phase differences when measuring the positive voltage. The phase difference range under positive voltage is determined based on the maximum and minimum phase differences under positive voltage; the lower limit of the phase difference range under positive voltage is the minimum phase difference, and the upper limit of the phase difference range under positive voltage is the maximum phase difference. The upper and lower limits of the phase difference under positive voltage are written into the sensor. Before leaving the factory, the same negative voltage to be measured is used with different sensors to determine the maximum and minimum phase differences when the negative voltage is measured. The phase difference range under negative voltage is determined based on the maximum and minimum phase differences under negative voltage; the lower limit of the phase difference range under negative voltage is the minimum phase difference, and the upper limit of the phase difference range under negative voltage is the maximum phase difference. The upper and lower limits of the phase difference under positive voltage are also written into the sensor. During the actual measurement, it is determined whether the measured phase difference between the changing voltage and the sinusoidal driving signal is within the phase difference range when the voltage is positive or when the voltage is negative. When the measured phase difference is within the phase difference range when the voltage is positive, the polarity of the voltage to be measured is determined to be positive. When the measured phase difference is within the phase difference range when the voltage is negative, the polarity of the voltage to be measured is determined to be negative.

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