An electrode device and method for measuring space charge by pressure-electric field-temperature coupling

Abstract

The application discloses a kind of electrode device and method for measuring space charge by pressure-electric field-temperature coupling, the device includes: upper electrode structure, including upper connecting plate, conductive bolt, cylindrical ceramic and upper electrode terminal;The bottom of conductive bolt is fixedly connected with upper connecting plate, the top has radial scale and can be contacted with the fixed surface of external calibration platform by thread feeding;Lower electrode structure, including lower connecting plate, plate ceramic and lower electrode terminal;Lower electrode terminal includes heating resistance wire;High-voltage pulse unit, two ends are connected to upper and lower electrode terminals respectively;Signal collection conversion unit is connected to lower electrode terminal;The sample to be tested is clamped between cylindrical ceramic and plate ceramic;Upper and lower connecting plates are engaged by connecting bolt to apply stress to the sample to be tested;Pressure sensor is arranged between each connecting bolt and upper connecting plate.The application has the functions of pressure regulation and real-time measurement of sample thickness, and can more accurately measure space charge in cable accessory insulating material.

Description

Technical Field

[0001] This invention belongs to the field of electrical insulation measuring devices, and relates to a measuring device for cable accessory insulation materials, specifically to an electrode device and method for measuring space charge using pressure-electric field-temperature coupling. Background Technology

[0002] The continuous accumulation of space charge in cable accessory insulation materials during operation has become a significant issue affecting equipment reliability. The accumulation of space charge can lead to localized electric field distortion, causing a gradient deterioration in insulation performance and creating potential insulation failure hazards. Section 9.2.1 of standard GB / T 22078.3-2008, "500kV (Um=550kV) Cross-linked Polyethylene Insulated Power Cables and Their Accessories Part 3: Accessories for 500kV (Um=550kV) Cross-linked Polyethylene Insulated Power Cables," specifies that accessories must withstand a pressure of 0.20±0.01MPa. Therefore, considering the coupled effects of pressure, electric field, and temperature, accurate measurement of space charge becomes a key technical challenge for accurately assessing the insulation condition.

[0003] The pulse-electroacoustic (PEA) method, currently the mainstream space charge characterization measurement technique, has a problem in practical applications: the mechanical pressure applied by the upper electrode and the fixed mold in the measurement system can cause non-uniform thickness deformation of the sample. This deformation process directly leads to a deviation between the measured thickness of the sample and the actual thickness during operation, resulting in a discrepancy between the actual measured electric field strength and the preset electric field strength. Simultaneously, the stress borne by the sample is often neglected. For example, the displacement deformation of the accompanying insulating materials, such as cross-linked polyethylene (Shore D hardness 50-70, elastic modulus range: 0.2GPa to 1GPa) and silicone rubber (Shore A hardness 20-90, elastic modulus range: 0.01GPa to 0.1GPa), will inevitably differ under the same stress applied by the fixed mold, but this is often ignored in actual measurements, affecting the accuracy of the measurement results.

[0004] Therefore, it is necessary to design an electrode device that combines pressure regulation and real-time sample thickness measurement. This is of great engineering value for studying the influence of pressure on space charge measurement and improving the accuracy of insulation status assessment of power equipment. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention patent proposes an electrode device that allows for pressure, electric field, and temperature coupling measurement of space charge in cable accessory insulation materials. Under the premise of controllable electric field and temperature, the device measures the material thickness as a function of pressure, thereby enabling more accurate measurement of space charge in cable accessory insulation materials.

[0006] The present invention adopts the following technical solution.

[0007] In a first aspect of the invention, an electrode device for pressure-electric field-temperature coupling measurement of space charge is provided. The electrode device includes: an upper electrode structure, a lower electrode structure, a high-voltage pulse unit, an external calibration platform, and a signal collection and conversion unit.

[0008] The upper electrode structure includes an upper connecting plate, a conductive bolt, and an upper electrode terminal; the bottom of the conductive bolt is fixedly connected to the upper connecting plate, and the top has radial graduations and can be fed through a thread to contact the fixed surface of the external calibration platform; the upper electrode terminal is fixed below the upper connecting plate.

[0009] The lower electrode structure includes a lower connecting plate and a lower electrode terminal; the lower electrode terminal is fixed on the lower connecting plate and includes a heating resistance wire.

[0010] The two ends of the high-voltage pulse unit are respectively connected to the upper electrode terminal and the lower electrode terminal, and are used to provide the set polarization voltage and high-voltage pulse to the test sample placed between the upper electrode terminal and the lower electrode terminal during the test;

[0011] The signal collection and conversion unit is connected to the lower electrode terminal;

[0012] The upper and lower connecting plates each have three symmetrically arranged threaded holes. The threaded holes of the upper and lower connecting plates are engaged by three connecting bolts to apply stress to the test sample. A pressure sensor is installed between each connecting bolt and the threaded hole of the upper connecting plate.

[0013] Preferably, the upper electrode terminal includes a cylindrical ceramic and a semiconducting sheet and a high-voltage metal terminal disposed at the center of the bottom of the cylindrical ceramic; the cylindrical ceramic is located at the center of the lower surface of the upper connecting plate;

[0014] The lower electrode terminal includes a plate-shaped ceramic and an aluminum electrode disposed at the center of the upper surface of the plate-shaped ceramic; the plate-shaped ceramic is fixedly disposed at the center of the upper surface of the lower connecting plate;

[0015] The semiconductive sheet and the aluminum electrode are in contact with the upper and lower surfaces of the sample to be tested, respectively.

[0016] The high-voltage metal terminal is connected to the high-voltage pulse unit via a wire; the wire is partially housed inside the conductive bolt.

[0017] Preferably, the bottom center of the cylindrical ceramic is recessed inward to form a groove; the high-voltage metal terminal and the semiconductive sheet are placed in the groove, and the high-voltage metal terminal is located between the bottom of the groove and the semiconductive sheet; the outer surface of the semiconductive sheet relative to the groove is flush with the bottom surface of the cylindrical ceramic.

[0018] Preferably, the outer diameter of the bottom surface of the cylindrical ceramic matches the outer diameter of the top surface of the plate-shaped ceramic, and is able to completely cover the test sample.

[0019] Preferably, the signal collection and conversion unit includes: a piezoelectric sensor, an acrylic glass, and a signal line assembly stacked sequentially below the lower electrode terminal; the signal line assembly includes a signal lead and silicone rubber covering the signal lead; the end of the signal lead away from the lower electrode terminal is formed as an SMA interface.

[0020] Preferably, the high-voltage pulse unit includes: a resistor R1, a DC power supply DC, a capacitor C1, and a high-voltage pulse generator; the positive terminal of the DC power supply DC is connected in series with the resistor R1 to form a first parallel branch; the capacitor C1 and the high-voltage pulse generator are connected in series to form a second parallel branch; the first branch and the second branch are connected in parallel; the positive terminal of the DC power supply DC is connected to the upper electrode terminal through the resistor R1; the negative terminal of the DC power supply DC is connected to the lower connecting plate and grounded.

[0021] Preferably, the external calibration platform is a cylindrical barrel made of glass, with openings at the bottom and sides, and the top of the barrel serving as a fixing surface for contact with the conductive bolts to achieve calibration; the upper electrode structure and the lower electrode structure are placed inside the barrel.

[0022] Preferably, the heating resistance wire is connected to a temperature controller. The temperature controller is used to sense the temperature of the test sample and to control and regulate the temperature of the test sample via the heating resistance wire.

[0023] In a second aspect of the invention, a method for measuring space charge using pressure-electric field-temperature coupling is provided, employing the electrode device described in the first aspect of the invention. The method includes the following steps:

[0024] Measure the initial thickness of the sample to be tested, and place the sample between the upper electrode terminal and the lower electrode terminal;

[0025] Determine the set sample pressure value, set polarization voltage value, and set temperature value for the current test cycle; based on the sample pressure value, calculate the corresponding reading of the pressure sensor at each threaded hole when the sample is subjected to the set sample pressure value;

[0026] Adjust the conductive bolt so that the top of the conductive bolt contacts the top of the external calibration platform, and read the first reading of the thread of the conductive bolt at this time. Tighten the three connecting bolts connected to the upper and lower connecting plates so that the pressure sensors at the three threaded holes all reach the corresponding calculated readings.

[0027] The set polarization voltage and pulse voltage are applied to the test sample, and the temperature of the test sample is adjusted to the set temperature value through the heating resistance wire. The sensing signal is acquired through the signal collection and conversion unit. After the temperature of the test sample stabilizes at the set temperature value, the calibration sample pressure value is obtained according to the reading of each pressure sensor. The conductive bolt is adjusted to contact the fixed surface of the external calibration platform again, and the second reading of the thread is read. The calibration thickness of the test sample is obtained according to the first reading and the second reading.

[0028] The acquired sensing signals are deconvolutionally processed, and the space charge data of the test sample under the calibration sample pressure value, the set polarization voltage value, and the set temperature value are obtained based on the deconvolution processing result and the calibration thickness.

[0029] Preferably, based on the sample pressure value, the corresponding reading of the pressure sensor at each threaded hole is calculated when the sample is subjected to the set sample pressure value, including:

[0030] If the pressure readings of each pressure sensor are recorded as F when the forces on the three connecting bolts are the same, then the total pressure on the test sample is determined to be 3F+G, where G is the sum of the weights of the conductive bolt, the three connecting bolts used for tightening, the pressure sensor, the upper connecting plate, the cylindrical ceramic, the high-voltage metal terminal, and the semi-conductive sheet.

[0031] By using the relationship between the readings and the total pressure on the test sample, the corresponding readings of the pressure sensors at each threaded hole can be calculated when the test sample is subjected to the set sample pressure value.

[0032] The beneficial effects of this invention are as follows: compared with the prior art, the temperature of the test sample can be controlled through the lower electrode terminal with a heating resistance wire; the micrometer-level displacement can be measured through the radial scale of the conductive bolt, and the real-time thickness of the test sample can be obtained based on the scale reading of the conductive bolt combined with the original thickness of the test sample; the stress applied to the test sample can be obtained based on the pressure sensor, thus combining pressure regulation and real-time sample thickness measurement functions. Furthermore, by combining the voltage data applied by the high-voltage pulse unit and the signal collected by the signal acquisition and conversion unit, the coupling measurement of pressure, electric field, and temperature for space charge testing of cable accessory insulation materials can be achieved more accurately. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the electrode device for measuring space charge using pressure-electric field-temperature coupling according to the present invention.

[0034] Figure 2 This is a schematic diagram of the structure of the lower electrode terminal and the signal collection and conversion unit in the electrode device of the present invention;

[0035] Figure 3 This is a schematic flowchart of the pressure-electric field-temperature coupling method for measuring space charge according to the present invention.

[0036] Wherein: 1 is the external calibration platform, 2 is the conductive bolt, 3 is the pressure sensor, 41 is the upper connecting plate, 42 is the lower connecting plate, 5 is the lead wire, 6 is the cylindrical ceramic, 7 is the high-voltage metal terminal, 8 is the semi-conductive sheet, 9 is the test sample, 10 is the signal amplifier, 11 is the aluminum electrode, 12 is the plate ceramic, 13 is the plexiglass, 14 is the signal lead wire, 15 is the silicone rubber, and 16 is the SMA interface. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of this invention. The embodiments described in this application are merely some embodiments of this invention, and not all embodiments. Based on the spirit of this invention, other embodiments obtained by those skilled in the art without creative effort are all within the protection scope of this invention.

[0038] Pulsed electroacoustic (PEA) method applies a short-duration, high-voltage pulsed electric field to a dielectric material, causing the space charge within the material to vibrate mechanically and emit sound waves. These sound waves are received by a piezoelectric sensor and converted into electrical signals. By analyzing the signal intensity and propagation time, the distribution of space charge within the material can be deduced. Existing PEA techniques achieve space charge measurement under different electric fields and temperatures by varying the applied voltage and adjusting the temperature of the heating electrodes.

[0039] However, in existing pulsed electroacoustic measurement systems, the mechanical pressure applied by the upper electrode and the fixed mold can cause non-uniform thickness deformation of the sample, which can further lead to distortion of the electric field distribution and introduce additional space charge measurement errors. At the same time, the existing measurement system also lacks the function of real-time monitoring of sample thickness changes, and cannot acquire thickness data synchronously during the pressure loading process, making it difficult to eliminate the space charge distribution measurement errors introduced by sample compression deformation.

[0040] Therefore, the core of this invention lies in effectively measuring the pressure borne by the sample and simultaneously measuring the displacement caused by stress deformation during sample installation, providing real-time feedback on stress changes throughout the entire space charge test. The invention will be further detailed below through specific embodiments.

[0041] Example 1

[0042] Example 1 provides an electrode device for measuring space charge using pressure-electric field-temperature coupling.

[0043] Specifically, such as Figure 1As shown, in this embodiment, the electrode device for measuring space charge by pressure-electric field-temperature coupling includes an upper electrode structure, a lower electrode structure, a high-voltage pulse unit, an external calibration platform, and a signal collection and conversion unit.

[0044] The upper electrode structure includes an upper connecting plate 41, a conductive bolt 2, and an upper electrode terminal. The bottom of the conductive bolt 2 is fixedly connected to the upper connecting plate 41, and the top has radial graduations and can be fed by threads to contact the fixed surface of the external calibration platform 1. The upper electrode terminal is fixed below the upper connecting plate 41.

[0045] The lower electrode structure includes a lower connecting plate 42 and a lower electrode terminal. The lower electrode terminal is fixed on the lower connecting plate 42 and includes a heating resistance wire.

[0046] The two ends of the high-voltage pulse unit are connected to the upper electrode terminal and the lower electrode terminal, respectively, to provide the set polarization voltage and high-voltage pulse to the test sample 9 placed between the upper electrode terminal and the lower electrode terminal during the test.

[0047] The signal acquisition and conversion unit is connected to the lower electrode terminal to convert the received voltage signal for subsequent analysis.

[0048] The upper connecting plate 41 and the lower connecting plate 42 each have three symmetrically arranged threaded holes. The threaded holes of the upper and lower connecting plates are engaged by three connecting bolts to apply stress to the test sample 9. A pressure sensor 3 is provided between each connecting bolt and the threaded hole of the upper connecting plate 41.

[0049] In this embodiment, the temperature of the test sample can be controlled via the lower electrode terminal with a heating resistance wire; the radial scale of the conductive bolt 2 allows for the measurement of micron-level displacement, and the real-time thickness of the test sample can be obtained based on the scale reading of the conductive bolt 2 combined with the original thickness of the test sample; the stress applied to the test sample 9 can be obtained based on the pressure sensor 3, thus combining pressure regulation and real-time sample thickness measurement functions. Furthermore, by combining the voltage data applied by the high-voltage pulse unit and the signal acquired by the signal collection and conversion unit, the coupling measurement of pressure, electric field, and temperature for space charge testing of cable accessory insulation materials can be achieved more accurately.

[0050] Furthermore, the upper electrode terminal includes a cylindrical ceramic 6, a semiconducting sheet 8 disposed at the center of the bottom of the cylindrical ceramic 6, and a high-voltage metal terminal 7. The cylindrical ceramic 6 is located at the center of the lower surface of the upper connecting plate 41. The lower electrode terminal includes a plate-shaped ceramic 12 and an aluminum electrode 11 disposed at the center of the upper surface of the plate-shaped ceramic 12. The plate-shaped ceramic 12 is fixedly disposed at the center of the upper surface of the lower connecting plate 42. The semiconducting sheet 8 and the aluminum electrode 11 are in contact with the upper and lower surfaces of the test sample 9, respectively. The high-voltage metal terminal 7 is connected to the high-voltage pulse unit via a wire, which is partially housed inside the conductive bolt 2. In this way, a high-voltage polarization field can be applied to the sample through the high-voltage pulse unit.

[0051] Furthermore, the cylindrical ceramic 6 has an inwardly recessed groove at its bottom center; the high-voltage metal terminal 7 and the semiconductive sheet 8 are placed within the groove, with the high-voltage metal terminal 7 positioned between the bottom of the groove and the semiconductive sheet 8; the outer surface of the semiconductive sheet 8 relative to the groove is flush with the bottom surface of the cylindrical ceramic 6. This ensures a smooth and horizontal connection between different layers, avoiding local tilting. Additionally, acoustic impedance matching can be achieved through the semiconductive sheet 8 positioned between the high-voltage metal terminal 7 and the test sample.

[0052] Furthermore, the outer diameter of the bottom surface of the cylindrical ceramic 6 matches the outer diameter of the top surface of the plate-shaped ceramic 12, and can completely cover the test sample. Here, "basically the same" means that the difference between their outer diameters is within ±0.2 cm (inclusive).

[0053] As an example, preferably, the outer diameter of the cylindrical ceramic 6 is 4.9 cm, the diameter of the high-voltage metal terminal 7 is 0.5 cm, and the thickness of the semiconducting sheet is 0.5 mm. The surface of the high-voltage metal terminal located at the center is slightly lower than the bottom plane of the cylindrical ceramic by 0.5 mm, and the 0.5 mm semiconducting sheet is embedded in this 0.5 mm recess to achieve acoustic impedance matching.

[0054] Preferably, the plate-shaped ceramic 12 has an outer diameter of 5 cm, an inner diameter of 4.9 cm, and a depth of 50 μm. The aluminum electrode 11 has a diameter of 2 cm.

[0055] Preferably, the pressure sensor outputs the applied pressure through the lead 5, and the magnitude of the applied pressure can be read. When the pressure sensor 3 at the three connecting bolts shows the same reading, it can accurately indicate whether the upper connecting plate is level.

[0056] Furthermore, such as Figure 2The signal collection and conversion unit includes a piezoelectric sensor 17, an acrylic glass 13, and a signal line assembly stacked sequentially below the lower electrode terminal. The signal line assembly includes a signal lead 14 and silicone rubber 15 covering the signal lead. The end of the signal lead 14 away from the lower electrode terminal is formed as an SMA (Sub-Miniature Version A connector) interface. Preferably, the piezoelectric sensor 17 is a PVDF (polyvinylidene fluoride) piezoelectric sensor, and the acrylic glass 13 is preferably PMMA (polymethyl methacrylate) acrylic glass. In this way, the charge inside the cable insulation is disturbed by a high-voltage pulse, generating an acoustic signal. This acoustic signal propagates radially to the lower electrode terminal, where the piezoelectric sensor converts it into an electrical signal for subsequent processing. The introduction of PMMA acrylic glass can absorb the reflected signals of the acoustic signal during propagation, avoiding their interference with the normal measurement signal. At the same time, PMMA acrylic glass can also reduce the influence of external noise or temperature changes on the experimental results. The SMA interface 16 connects to the signal amplifier 10 to transmit a space charge pulse signal, which is then connected to an oscilloscope to output the space charge signal.

[0057] Furthermore, the high-voltage pulse unit includes: a resistor R1, a DC power supply DC, a capacitor C1, and a high-voltage pulse generator; the positive terminal of the DC power supply DC is connected in series with the resistor R1 to form a first parallel branch; the capacitor C1 and the high-voltage pulse generator are connected in series to form a second parallel branch; the first branch and the second branch are connected in parallel; the positive terminal of the DC power supply DC is connected to the upper electrode terminal through the resistor R1; the negative terminal of the DC power supply DC is connected to the lower connecting plate and grounded.

[0058] Furthermore, the external calibration platform 1 is a cylindrical glass casing with openings at the bottom and sides. The top of the casing serves as a fixing surface for contact with the conductive bolts 2 to achieve calibration. The upper and lower electrode structures are housed within the casing. The high-voltage pulse unit, external calibration platform, and signal acquisition and conversion unit can be placed inside or outside the casing, depending on the specific circumstances. When placed outside the casing, electrical and signal connections can be established with the upper and lower electrode structures through the side openings of the casing.

[0059] Furthermore, the heating resistance wire included in the lower electrode terminal is connected to a temperature controller, which is used to sense the temperature of the test sample and control and adjust the temperature of the test sample via the heating resistance wire.

[0060] Example 2

[0061] This embodiment provides a method for measuring space charge using pressure-electric field-temperature coupling, which employs the electrode device for measuring space charge using pressure-electric field-temperature coupling of the present invention. Specifically, as shown... Figure 3The method includes the following steps:

[0062] S1. Measure the initial thickness of the test sample and place the test sample between the upper electrode terminal and the lower electrode terminal.

[0063] Wherein, the thickness H is the thickness of the sample under test when it is not subjected to pressure or stress.

[0064] The sample to be tested is preferably a square or circular sheet.

[0065] Preferably, the surfaces of the upper and lower electrode terminals that contact the sample under test can completely cover the sample. More preferably, when the sample under test is sandwiched between the upper and lower electrode terminals, its upper surface can completely cover the semiconducting sheet 8 in the upper electrode terminal, and its lower surface can completely cover the aluminum electrode 11 (with a diameter of, for example, 2 cm) in the lower electrode terminal, and its size does not exceed the cylindrical ceramic (with an outer diameter of, for example, 4.9 cm) below the upper electrode terminal. In this way, it can be ensured that all the applied stress falls on the sample under test, and at the same time, the sample under test completely covers the semiconducting sheet 8 and the grounded aluminum electrode 11, which can reduce the risk of surface discharge.

[0066] S2. Determine the set sample pressure value, set polarization voltage value, and set temperature value for the current test cycle; based on the sample pressure value, calculate the corresponding reading of the pressure sensor at each threaded hole when the sample is subjected to the set sample pressure value.

[0067] Specifically, if the pressure readings of each pressure sensor are denoted as F when the forces on the three connecting bolts are consistent, then the real-time total pressure on the sample is determined as 3F + G. Taking the electrode device structure described in Embodiment 1 of this invention as an example, G is the sum of the weights of the conductive bolt, the three connecting bolts used for tightening, the pressure sensor, the upper connecting plate, the cylindrical ceramic, the high-voltage metal terminal, and the semi-conductive sheet. Based on the above relationship, the corresponding reading of the pressure sensor at each threaded hole can be deduced when the sample to be tested is subjected to the set sample pressure value.

[0068] S3. Adjust the conductive bolt so that the top of the conductive bolt contacts the top of the external calibration platform. Read the first reading of the thread of the conductive bolt at this time. Tighten the three connecting bolts connected to the upper and lower connecting plates so that the pressure sensors at the three threaded holes all reach the corresponding calculated readings.

[0069] By reading the pressure sensor readings to ensure consistent force at the three points, the upper connecting plate can be kept horizontal, thus ensuring that the pressure applied to the test sample by the electrode device is uniform, thereby minimizing measurement errors and improving the accuracy of thickness measurement of the compressed sample.

[0070] S4. Apply the set polarization voltage and pulse voltage to the test sample, and adjust the temperature of the test sample to the set temperature value through the heating resistance wire. Acquire the sensing signal through the signal collection and conversion unit. After the temperature of the test sample stabilizes at the set temperature value, obtain the calibration sample pressure value according to the reading of each pressure sensor, and adjust the conductive bolt to contact the fixed surface of the external calibration platform again. Read the second reading of the thread, and obtain the calibration thickness of the test sample according to the first reading and the second reading.

[0071] In this step, if the first reading is denoted as A and the second reading as B, then the sample deformation displacement is AB. Using this sample deformation displacement, and in conjunction with the initial thickness H of the sample to be tested, the calibration thickness H' of the sample to be tested can be obtained.

[0072] More specifically, this step may also include applying a pulse of a certain intensity to the sample under a certain electric field strength via a high-voltage pulse unit, disturbing the polarization voltage, causing the charges within to vibrate under the action of Coulomb force and generate a sound pressure signal. This sound pressure signal is received by a piezoelectric sensor, converted into an electrical signal, and transmitted to an oscilloscope via a signal lead and SMA interface. The oscilloscope then communicates with a computer for data reading and storage. Therefore, this sound pressure signal can reflect the space charge density within the sample.

[0073] S5. Perform deconvolution processing on the acquired sensing signal, and obtain the space charge data of the test sample under the calibration sample pressure value, the set polarization voltage value and the set temperature value based on the deconvolution processing result and the calibration thickness.

[0074] Specifically, the purpose of deconvolution processing is to eliminate the distortion of the original signal caused by the inherent response of the testing system (sensors, amplifiers, cables, etc.), thereby obtaining a more realistic sound pressure signal to more accurately reflect the space charge density. The thickness of the sample serves as a bridge to convert the time-domain sound pressure signal into a spatial distribution. The speed of sound propagation in the material (sound velocity v) is known or measurable, and the location x of the charge is calculated by multiplying the time difference of the sound wave signal by the sound velocity v.

[0075] The specific deconvolution processing and inversion process can be implemented by existing professional software, and will not be elaborated here.

[0076] Furthermore, in the new test cycle, the set sample pressure value, set polarization voltage value, and set temperature value can be adjusted. Each time the set temperature value is adjusted, the displacement deformation of the sample affected by temperature is obtained by reading the readings of the conductive bolt before and after the temperature adjustment, and a new calibration sample thickness and a new calibration sample pressure value are obtained. In turn, space charge data under different calibration sample pressure values, different set polarization voltage values, and different set temperature values ​​are obtained.

[0077] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the protection scope of the claims of the present invention.

Claims

1. An electrode device for measuring space charge using pressure-electric field-temperature coupling, characterized in that, include: Upper electrode structure, lower electrode structure, high voltage pulse unit, external calibration platform and signal collection and conversion unit; The upper electrode structure includes an upper connecting plate, a conductive bolt, and an upper electrode terminal; the bottom of the conductive bolt is fixedly connected to the upper connecting plate, and the top has radial graduations and can be fed through a thread to contact the fixed surface of the external calibration platform; the upper electrode terminal is fixed below the upper connecting plate; the lower electrode structure includes a lower connecting plate and a lower electrode terminal; the lower electrode terminal is fixed to the lower connecting plate and includes a heating resistance wire; the two ends of the high-voltage pulse unit are respectively connected to the upper electrode terminal and the lower electrode terminal, and are used to provide a set polarization voltage and pulse voltage to the test sample placed between the upper electrode terminal and the lower electrode terminal during testing; the signal collection and conversion unit is connected to the lower electrode terminal; The upper and lower connecting plates each have three symmetrically arranged threaded holes. The threaded holes of the upper and lower connecting plates are engaged by three connecting bolts to apply stress to the test sample. A pressure sensor is installed between each connecting bolt and the threaded hole of the upper connecting plate.

2. The electrode device for measuring space charge using pressure-electric field-temperature coupling according to claim 1, characterized in that, The upper electrode terminal includes a cylindrical ceramic and a semiconducting sheet and a high-voltage metal terminal disposed at the center of the bottom of the cylindrical ceramic; the cylindrical ceramic is located at the center of the lower surface of the upper connecting plate; The lower electrode terminal includes a plate-shaped ceramic and an aluminum electrode disposed at the center of the upper surface of the plate-shaped ceramic; the plate-shaped ceramic is fixedly disposed at the center of the upper surface of the lower connecting plate; The semiconductive sheet and the aluminum electrode are in contact with the upper and lower surfaces of the sample to be tested, respectively. The high-voltage metal terminal is connected to the high-voltage pulse unit via a wire; The wire is partially housed inside the conductive bolt.

3. The electrode device for measuring space charge using pressure-electric field-temperature coupling according to claim 2, characterized in that, The bottom center of the cylindrical ceramic is recessed inward to form a groove; the high-voltage metal terminal and the semiconducting sheet are placed in the groove, and the high-voltage metal terminal is located between the bottom of the groove and the semiconducting sheet; the outer surface of the semiconducting sheet relative to the groove is flush with the bottom surface of the cylindrical ceramic.

4. The electrode device for measuring space charge using pressure-electric field-temperature coupling according to claim 2, characterized in that, The outer diameter of the bottom surface of the cylindrical ceramic matches the outer diameter of the top surface of the plate-shaped ceramic, and can completely cover the test sample.

5. The electrode device for measuring space charge using pressure-electric field-temperature coupling according to claim 1, characterized in that, The signal collection and conversion unit includes: a piezoelectric sensor, an acrylic glass, and a signal line assembly stacked sequentially below the lower electrode terminal; the signal line assembly includes a signal lead and silicone rubber covering the signal lead; the end of the signal lead away from the lower electrode terminal is formed as an SMA interface.

6. The electrode device for measuring space charge using pressure-electric field-temperature coupling according to claim 1, characterized in that, The high-voltage pulse unit includes: a resistor R1, a DC power supply DC, a capacitor C1, and a high-voltage pulse generator; the positive terminal of the DC power supply DC is connected in series with the resistor R1 to form a first parallel branch; the capacitor C1 and the high-voltage pulse generator are connected in series to form a second parallel branch; the first parallel branch and the second parallel branch are connected in parallel. The positive terminal of the DC power supply is connected to the upper electrode terminal through resistor R1; the negative terminal of the DC power supply is connected to the lower connecting plate and grounded.

7. The electrode device for measuring space charge using pressure-electric field-temperature coupling according to claim 1, characterized in that, The external calibration platform is a cylindrical barrel made of glass, with openings at the bottom and sides, and the top of the barrel serving as a fixing surface for contact with the conductive bolts to achieve calibration; the upper electrode structure and the lower electrode structure are placed inside the barrel.

8. The electrode device for measuring space charge using pressure-electric field-temperature coupling according to claim 1, characterized in that, The heating resistance wire is connected to a temperature controller; the temperature controller is used to sense the temperature of the test sample and control and adjust the temperature of the test sample via the heating resistance wire.

9. A method for measuring space charge using pressure-electric field-temperature coupling, characterized in that, The method, using the electrode device as described in any one of claims 1-8, comprises the following steps: Measure the initial thickness of the sample to be tested, and place the sample between the upper electrode terminal and the lower electrode terminal; Determine the set sample pressure, set polarization voltage, and set temperature values ​​for the current test cycle; Based on the sample pressure value, calculate the corresponding reading of the pressure sensor at each threaded hole when the sample is subjected to the set sample pressure value; Adjust the conductive bolt so that the top of the conductive bolt contacts the top of the external calibration platform, and read the first reading of the thread of the conductive bolt at this time. Tighten the three connecting bolts connected to the upper and lower connecting plates so that the pressure sensors at the three threaded holes all reach the corresponding calculated readings. The set polarization voltage and pulse voltage are applied to the test sample, and the temperature of the test sample is adjusted to the set temperature value through the heating resistance wire. The sensing signal is acquired through the signal collection and conversion unit. After the temperature of the test sample stabilizes at the set temperature value, the calibration sample pressure value is obtained according to the reading of each pressure sensor. The conductive bolt is adjusted to contact the fixed surface of the external calibration platform again, and the second reading of the thread is read. The calibration thickness of the test sample is obtained according to the first reading and the second reading. The acquired sensing signals are deconvolutionally processed, and the space charge data of the test sample under the calibration sample pressure value, the set polarization voltage value, and the set temperature value are obtained based on the deconvolution processing result and the calibration thickness.

10. The method for measuring space charge using pressure-electric field-temperature coupling according to claim 9, characterized in that, Based on the sample pressure value, calculate the corresponding reading of the pressure sensor at each threaded hole when the sample is subjected to the set sample pressure value, including: If the pressure readings of each pressure sensor are recorded as F when the forces on the three connecting bolts are the same, then the total pressure on the test sample is determined to be 3F+G, where G is the sum of the weights of the conductive bolt, the three connecting bolts used for tightening, the pressure sensor, the upper connecting plate, the cylindrical ceramic, the high-voltage metal terminal, and the semi-conductive sheet. By using the relationship between the readings and the total pressure on the test sample, the corresponding readings of the pressure sensors at each threaded hole can be calculated when the test sample is subjected to the set sample pressure value.

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