Method and apparatus for electrical steel sheet dielectric relaxation testing

Abstract

The application provides an electrical steel sheet dielectric relaxation test method and device, which comprises the following steps: building a test environment of the electrical steel sheet, and controlling the temperature of the electrical steel sheet to a preset temperature value; applying an alternating voltage signal to the metal base layer of the electrical steel sheet and collecting a current signal of the insulating layer, and calculating a dielectric spectrum curve of the insulating layer of the electrical steel sheet; changing the applied alternating voltage signal, calculating a dielectric spectrum curve group of the electrical steel sheet under different alternating voltages; adjusting the preset temperature value, calculating a dielectric temperature spectrum curve group of the electrical steel sheet under different temperatures; and completing the test of the dielectric relaxation of the electrical steel sheet based on the dielectric spectrum curve group and the dielectric temperature spectrum curve group. The method combines the dielectric relaxation test with the microstructure characterization of the electrical steel sheet, realizes the high-precision characterization of the microstructure of the insulating layer and the pinning object of the metal base layer of the electrical steel sheet, can provide abundant information of the insulating layer and the pinning object, and improves the operation efficiency.

Description

Technical Field

[0001] This invention relates to the field of dielectric relaxation testing technology, and in particular to a method and apparatus for testing the dielectric relaxation of electrical steel sheets. Background Technology

[0002] To develop electrical steel sheets with low loss and high performance, it is necessary to characterize the microstructure of the surface insulation layer and the metal base studs of the electrical steel sheet. Existing characterization methods mainly include testing the insulation resistance of the electrical steel sheet and observing the electrical steel sheet by electron microscopy after slicing it.

[0003] One method, testing the insulation resistance of electrical steel sheets, can only analyze the electrical properties of the surface insulation layer. It provides limited information about the steel sheet coating and cannot distinguish between the surface insulation layer and embedded studs, thus failing to accurately describe the microstructural characteristics of the steel sheet surface. While electron microscopy observation of slicing the electrical steel sheet can reveal the insulation layer thickness, properties, and the size and depth of the studs, it is cumbersome and relies heavily on manual experience. Furthermore, because the studs are irregularly distributed, repeated slicing is required to ensure their observation at the cross-section, resulting in low observation efficiency. Summary of the Invention

[0004] The present invention aims to provide a method and apparatus for testing the dielectric relaxation of electrical steel sheets to solve the above-mentioned technical problems. By using the dielectric relaxation test process to characterize the microstructure of the insulating layer and the metal base studs on the surface of the electrical steel sheet, it can provide rich information about the insulating layer and studs, and effectively improve the operational efficiency.

[0005] To address the aforementioned technical problems, this invention provides a method for testing the dielectric relaxation of electrical steel sheets, comprising the following steps:

[0006] Set up the test environment for the electrical steel sheet and control the temperature of the electrical steel sheet to the preset temperature value;

[0007] An alternating voltage signal is applied to the metal base layer of the electrical steel sheet and the current signal of the insulation layer is collected. The dielectric spectrum curve of the insulation layer of the electrical steel sheet is then calculated.

[0008] By changing the applied alternating voltage signal, calculate the dielectric spectrum curves of the electrical steel sheet under different alternating voltages;

[0009] Adjust the preset temperature value and calculate the dielectric temperature spectrum curves of the electrical steel sheet at different temperatures;

[0010] The dielectric relaxation of electrical steel sheets was tested based on the dielectric spectrum curve set and the dielectric temperature spectrum curve set.

[0011] The above scheme uses an alternating voltage signal to induce dielectric relaxation between the studs and the insulation layer within the metal substrate of the electrical steel sheet. Since the characteristic frequency band of the dielectric relaxation response of the insulation layer differs from that of the studs, the structural characteristics of the insulation layer and studs on the surface of the electrical steel sheet can be directly derived and determined by calculating the dielectric spectrum curves of the electrical steel sheet under different alternating voltages and the dielectric temperature spectrum curves at different temperatures. This achieves high-precision characterization of the electrical steel sheet structure.

[0012] The above scheme makes full use of the dielectric relaxation test process, organically combining dielectric relaxation test with the microstructure characterization of electrical steel sheets, and realizes high-precision characterization of the microstructure of the insulating layer and metal base studs on the surface of electrical steel sheets. It can provide rich information on the insulating layer and studs, and effectively improve operational efficiency.

[0013] Furthermore, the construction of the test environment for the electrical steel sheet and the control of the temperature of the electrical steel sheet to a preset temperature value specifically involves: constructing the test environment for the electrical steel sheet based on the four-wire balance method and controlling the temperature of the electrical steel sheet to a preset temperature value.

[0014] In the above scheme, the electrical steel sheet testing environment built based on the four-wire balance method can significantly improve the accuracy of dielectric relaxation testing and further improve the precision of electrical steel sheet structural characterization.

[0015] Furthermore, the test environment for the electrical steel sheet built based on the four-wire balance method, and the temperature of the electrical steel sheet controlled to a preset temperature value, specifically involves: building the test environment for the electrical steel sheet based on dual high-voltage electrodes and dual test electrodes, and establishing a connection relationship between the dual high-voltage electrodes and dual test electrodes with the electrical steel sheet at equal intervals in the order of high-voltage electrode-test electrode-high-voltage electrode-test electrode; the high-voltage electrodes are used to apply alternating voltage signals to the metal base layer of the electrical steel sheet; and the test electrodes are used to collect current signals from the insulation layer.

[0016] In the above scheme, the use of dual high-voltage electrodes effectively avoids the voltage drop generated by a single high-voltage electrode across the electrical steel sheet's metal substrate, making the potential at various locations on the metal substrate more uniform and reducing test system errors caused by alternating voltage imbalances on the metal substrate. The use of dual test electrodes reduces random test errors caused by inhomogeneities in the insulation layer of the electrical steel sheet. Therefore, the electrical steel sheet testing environment built using the four-wire balance method with dual high-voltage and dual test electrodes can significantly improve the accuracy of dielectric relaxation testing and further enhance the precision of electrical steel sheet structural characterization.

[0017] Furthermore, the test environment for constructing the electrical steel sheet based on dual high-voltage electrodes and dual test electrodes, and establishing a connection relationship between the dual high-voltage electrodes and dual test electrodes with the electrical steel sheet at equal intervals in the order of high-voltage electrode-test electrode-test electrode-high-voltage electrode, includes: establishing a connection relationship between the test electrodes and the electrical steel sheet by applying pressure to the test electrodes.

[0018] In the above scheme, applying pressure to the test electrode to fix the connection between the test electrode and the electrical steel sheet can maintain the consistency of the connection between different test electrodes, ensure fewer variables in each test and calculation, improve the final test accuracy, and further improve the precision of the electrical steel sheet structure characterization.

[0019] Furthermore, the process of setting up a test environment for the electrical steel sheet and controlling the temperature of the electrical steel sheet to a preset temperature value specifically involves: setting up a test environment for the electrical steel sheet and controlling the temperature of the electrical steel sheet to a preset temperature value through heat conduction.

[0020] In the above scheme, the temperature of the electrical steel sheet is controlled by heat conduction, which is convenient to implement and can ensure uniform heating of the electrical steel sheet, reduce test errors caused by temperature, and achieve accurate description of the microstructure characteristics of the surface of the electrical steel sheet.

[0021] The above-mentioned scheme eliminates the need to determine the distribution of the pins in the microstructure of the insulation layer and the metal base layer of the electrical steel sheet, greatly simplifying the testing process and improving the efficiency and accuracy of the characterization.

[0022] This invention also provides a dielectric relaxation testing device for electrical steel sheets, comprising a high-voltage electrode module, a test electrode module, a processing and control module, and a temperature control module; wherein:

[0023] The high-voltage electrode module is used to apply an alternating voltage signal to the metal substrate of the electrical steel sheet;

[0024] The test electrode module is used to collect the insulation layer current signal of the electrical steel sheet and transmit it to the processing and control module;

[0025] The processing control module is used to control the high voltage electrode module to generate different alternating voltage signals and to preset the preset temperature value of the temperature control module, and to calculate the dielectric spectrum curves of the electrical steel sheet under different alternating voltages and the dielectric temperature spectrum curves of the electrical steel sheet at different temperatures.

[0026] The temperature control module is used to control the temperature of the electrical steel sheet to a preset temperature value.

[0027] The above-described method provides a technical means to analyze the dielectric relaxation phenomenon of the insulation layer and the staples. It avoids the limitations of existing methods that rely on cutting electrical steel sheets, eliminating the need for microscopic observation. Instead, it directly derives and determines the structural characteristics of the insulation layer and staples on the surface of the electrical steel sheet by calculating the dielectric spectrum curves under different alternating voltages and dielectric temperature spectrum curves at different temperatures. This achieves high-precision characterization of the electrical steel sheet structure. The dielectric spectrum curves obtained by this testing device contain rich information on dielectric relaxation, reflecting the dielectric behavior of the staples in different frequency domains and temperature ranges.

[0028] Furthermore, the high-voltage electrode module and the test electrode module are used to build a test environment for electrical steel sheets based on the four-wire balancing method.

[0029] Furthermore, the high-voltage electrode module applies an alternating voltage signal to the metal substrate of the electrical steel sheet through dual high-voltage electrodes; the test electrode module acquires the insulation layer current signal of the electrical steel sheet through dual test electrodes; the high-voltage electrode module and the test electrode module construct the test environment for the electrical steel sheet based on the four-wire balance method, specifically as follows:

[0030] The test environment for electrical steel sheets is constructed based on dual high-voltage electrodes and dual test electrodes. The dual high-voltage electrodes and dual test electrodes are connected to the electrical steel sheets at equal intervals in the order of high-voltage electrode-test electrode-test electrode-high-voltage electrode.

[0031] In the above scheme, an alternating voltage signal is applied to the metal substrate of the electrical steel sheet using dual high-voltage electrodes. This avoids the large resistivity difference between the metal substrate and the high-voltage electrodes, which could create contact resistance and interfere with the test results. The insulation layer current signal of the electrical steel sheet is acquired using dual test electrodes, avoiding interference from the uneven surface of the insulation layer when a single test electrode is in contact. The electrical steel sheet testing environment, built using the four-wire balance method with dual high-voltage and dual test electrodes, can significantly improve the accuracy of dielectric relaxation testing and further enhance the precision of the electrical steel sheet structural characterization.

[0032] Furthermore, the dielectric relaxation testing device for electrical steel sheets also includes a pressure application module controlled by the processing control module. The pressure application module is used to apply pressure to the test electrode to establish a connection between the test electrode and the electrical steel sheet.

[0033] Furthermore, the temperature control module controls the temperature of the electrical steel sheet to a preset temperature value through heat conduction. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of a dielectric relaxation test method for electrical steel sheets provided in an embodiment of the present invention;

[0035] Figure 2This is a schematic diagram of the module connection of an electrical steel sheet dielectric relaxation testing device according to an embodiment of the present invention;

[0036] Figure 3 This is a schematic diagram of the module connection for a specific application of an electrical steel sheet dielectric relaxation testing device according to an embodiment of the present invention.

[0037] The components include: 1. High-voltage electrode module; 11. Drill bit; 12. Alternating power supply; 2. Test electrode module; 21. Microammeter; 22. Contact electrode; 3. Processing control module; 4. Temperature control module; 41. Metal base plate; 42. Cooling medium inlet and outlet; 5. Pressure application module; 51. Pressure sensor; 6. Electrical steel sheet; 61. Metal base layer; 62. Insulation layer; 63. Nail material. Detailed Implementation

[0038] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] In the following embodiments, electrical steel sheets, which can also be electrical steel strips, are the core material for manufacturing transformer cores. Their condition directly affects the safe and stable operation of transformer equipment, therefore, characterizing their structure is of great significance. By coating an insulating layer on the surface of a metal base layer, the electrical steel sheet effectively reduces eddy current losses in the core and prevents localized overheating and transformer failures by blocking interlayer current conduction through the insulating medium. The insulating layer is approximately 3 micrometers thick and transitions continuously into the metal base layer. During the heat treatment process in the manufacturing of the electrical steel sheet, inorganic oxides (mainly SiO2) in the insulating layer penetrate into the metal base layer, forming anchors. Both the insulating layer on the surface of the electrical steel sheet and the anchors within the metal base layer affect the interlayer resistance and eddy current losses of the electrical steel sheet. Therefore, testing and analyzing the insulating layer on the surface of the electrical steel sheet and the anchors within the metal base layer is the technical foundation for developing low-loss, high-performance electrical steel sheets.

[0040] To perform testing and analysis of the insulation layer on the surface of electrical steel sheets and the nails embedded in the metal base layer, please refer to [link to relevant documentation]. Figure 1 This embodiment provides a method for testing the dielectric relaxation of electrical steel sheets, including the following steps:

[0041] S1: Set up the test environment for the electrical steel sheet and control the temperature of the electrical steel sheet to the preset temperature value;

[0042] S2: Apply an alternating voltage signal to the metal base layer of the electrical steel sheet and collect the current signal of the insulation layer to calculate the dielectric spectrum curve of the insulation layer of the electrical steel sheet;

[0043] S3: Change the applied alternating voltage signal and calculate the dielectric spectrum curves of the electrical steel sheet under different alternating voltages;

[0044] S4: Adjust the preset temperature value and calculate the dielectric temperature spectrum curves of the electrical steel sheet at different temperatures;

[0045] S5: Test the dielectric relaxation of electrical steel sheets based on the dielectric spectrum curve set and dielectric temperature spectrum curve set.

[0046] This embodiment uses an alternating voltage signal on the electrical steel sheet to induce dielectric relaxation between the studs and the insulation layer within the metal substrate of the electrical steel sheet. Since the characteristic frequency band of the dielectric relaxation response of the insulation layer differs from that of the studs, by calculating the dielectric spectrum curves of the electrical steel sheet under different alternating voltages and the dielectric temperature spectrum curves at different temperatures, the structural characteristics of the insulation layer and studs on the surface of the electrical steel sheet can be directly derived and determined, achieving high-precision characterization of the electrical steel sheet structure.

[0047] This embodiment makes full use of the dielectric relaxation test process, organically combining dielectric relaxation testing with the microstructure characterization of electrical steel sheets. This achieves high-precision characterization of the microstructure of the surface insulation layer and metal base studs of the electrical steel sheets, providing a technical foundation for the development of low-loss electrical steel sheets. This is beneficial for reducing power equipment losses. Furthermore, the dielectric relaxation test process can be automated, with a simple and quick operation, which can improve operational efficiency.

[0048] Furthermore, the construction of the test environment for the electrical steel sheet and the control of the temperature of the electrical steel sheet to a preset temperature value specifically involves: constructing the test environment for the electrical steel sheet based on the four-wire balance method and controlling the temperature of the electrical steel sheet to a preset temperature value.

[0049] In this embodiment, the electrical steel sheet testing environment built based on the four-wire balance method can significantly improve the accuracy of dielectric relaxation testing and further enhance the precision of electrical steel sheet structural characterization.

[0050] Furthermore, the test environment for the electrical steel sheet built based on the four-wire balance method, and the temperature of the electrical steel sheet controlled to a preset temperature value, specifically involves: building the test environment for the electrical steel sheet based on dual high-voltage electrodes and dual test electrodes, and establishing a connection relationship between the dual high-voltage electrodes and dual test electrodes with the electrical steel sheet at equal intervals in the order of high-voltage electrode-test electrode-high-voltage electrode-test electrode; the high-voltage electrodes are used to apply alternating voltage signals to the metal base layer of the electrical steel sheet; and the test electrodes are used to collect current signals from the insulation layer.

[0051] In this embodiment, the use of dual high-voltage electrodes effectively avoids the voltage drop generated by a single high-voltage electrode across the electrical steel sheet's metal substrate, making the potential at various locations on the metal substrate more uniform and reducing test system errors caused by alternating voltage imbalances on the metal substrate. Furthermore, the use of dual test electrodes reduces random test errors caused by inhomogeneities in the insulation layer of the electrical steel sheet. Therefore, the electrical steel sheet testing environment built using the four-wire balance method with dual high-voltage and dual test electrodes can significantly improve the accuracy of dielectric relaxation testing and further enhance the precision of the electrical steel sheet's structural characterization.

[0052] Furthermore, the test environment for constructing the electrical steel sheet based on dual high-voltage electrodes and dual test electrodes, and establishing a connection relationship between the dual high-voltage electrodes and dual test electrodes with the electrical steel sheet at equal intervals in the order of high-voltage electrode-test electrode-test electrode-high-voltage electrode, includes: establishing a connection relationship between the test electrodes and the electrical steel sheet by applying pressure to the test electrodes.

[0053] In this embodiment, applying pressure to the test electrode to fix the connection between the test electrode and the electrical steel sheet can maintain the consistency of the connection between different test electrodes, ensure fewer variables in each test and calculation, improve the final test accuracy, and further improve the precision of the electrical steel sheet structure characterization.

[0054] Furthermore, the process of setting up a test environment for the electrical steel sheet and controlling the temperature of the electrical steel sheet to a preset temperature value specifically involves: setting up a test environment for the electrical steel sheet and controlling the temperature of the electrical steel sheet to a preset temperature value through heat conduction.

[0055] In this embodiment, the temperature of the electrical steel sheet is controlled by heat conduction, which is convenient to implement and can ensure uniform heating of the electrical steel sheet, reduce test errors caused by temperature, and achieve an accurate description of the microstructure characteristics of the surface of the electrical steel sheet.

[0056] In this embodiment, the distribution of the pins on the surface insulation layer and metal base layer of the electrical steel sheet does not need to be determined during the characterization process, which greatly simplifies the testing process and improves the efficiency and accuracy of the characterization.

[0057] Please see Figure 2 This embodiment provides a dielectric relaxation testing device for electrical steel sheets, which can realize a method for testing the dielectric relaxation of electrical steel sheets. It includes a high-voltage electrode module 1, a test electrode module 2, a processing and control module 3, and a temperature control module 4; wherein:

[0058] The high-voltage electrode module 1 is used to apply an alternating voltage signal to the metal base layer 61 of the electrical steel sheet 6;

[0059] The test electrode module 2 is used to collect the current signal of the insulation layer 62 of the electrical steel sheet 6 and transmit it to the processing and control module 3;

[0060] The processing control module 3 is used to control the high voltage electrode module 1 to generate different alternating voltage signals and to preset the preset temperature value of the temperature control module 4, and to calculate the dielectric spectrum curve set of the electrical steel sheet 6 under different alternating voltages and the dielectric temperature spectrum curve set of the electrical steel sheet 6 at different temperatures.

[0061] The temperature control module 4 is used to control the temperature of the electrical steel sheet 6 to a preset temperature value.

[0062] This embodiment provides a technical means to analyze the dielectric relaxation phenomenon of the insulating layer 62 and the staples. It avoids the limitations of existing methods that rely on cutting the electrical steel sheet 6, eliminating the need for microscopic observation. Instead, it directly derives and determines the structural characteristics of the insulating layer 62 and the staples by calculating the dielectric spectrum curves of the electrical steel sheet 6 under different alternating voltages and at different temperatures. This achieves high-precision characterization of the electrical steel sheet 6 structure. The dielectric spectrum curves obtained by this testing device contain rich information on dielectric relaxation, reflecting the dielectric behavior of the staples in different frequency domains and temperature ranges.

[0063] Furthermore, the high-voltage electrode module 1 and the test electrode module 2 are used to build the test environment for the electrical steel sheet 6 based on the four-wire balance method.

[0064] Furthermore, the high-voltage electrode module 1 applies an alternating voltage signal to the metal substrate 61 of the electrical steel sheet 6 through dual high-voltage electrodes; the test electrode module 2 acquires the current signal of the insulation layer 62 of the electrical steel sheet 6 through dual test electrodes; the high-voltage electrode module 1 and the test electrode module 2 construct the test environment for the electrical steel sheet 6 based on the four-wire balance method, specifically as follows:

[0065] The test environment for the electrical steel sheet 6 is constructed based on the dual high-voltage electrodes and dual test electrodes. The dual high-voltage electrodes and dual test electrodes are connected to the electrical steel sheet 6 at equal intervals in the order of high-voltage electrode-test electrode-test electrode-high-voltage electrode.

[0066] In this embodiment, an alternating voltage signal is applied to the metal substrate 61 of the electrical steel sheet 6 using dual high-voltage electrodes. This avoids the formation of contact resistance due to a large resistivity difference between the metal substrate 61 and the high-voltage electrodes, which could interfere with the test results. The current signal of the insulation layer 62 of the electrical steel sheet 6 is acquired using dual test electrodes, avoiding interference from the uneven surface of the insulation layer 62 when a single test electrode is in contact. The test environment for the electrical steel sheet 6, constructed using the dual high-voltage electrodes and dual test electrodes based on the four-wire balance method, can significantly improve the accuracy of dielectric relaxation testing and further enhance the precision of structural characterization of the electrical steel sheet 6.

[0067] Furthermore, the dielectric relaxation test device for electrical steel sheets also includes a pressure application module 5 controlled by the processing control module 3. The pressure application module 5 is used to apply pressure to the test electrode so that the test electrode and the electrical steel sheet 6 are connected.

[0068] Furthermore, the temperature control module 4 controls the temperature of the electrical steel sheet 6 to a preset temperature value through heat conduction.

[0069] Furthermore, to describe the technical solution provided by the present invention in more detail and highlight its technical advantages and features, this embodiment provides a device for a specific application of the dielectric relaxation testing device for electrical steel sheets. Please refer to [link to relevant documentation] for details. Figure 3 .

[0070] The high-voltage electrode module of the dielectric relaxation testing device for electrical steel sheets provided in this embodiment comprises a drill bit 11 and an alternating power supply 12. The test electrode module includes a microammeter 21 and contact electrodes 22. The pressure application module includes a pressure device and a pressure sensor 51. The electrical steel sheet includes a metal base layer 61, an insulating layer 62, and anchoring elements 63. The temperature control module includes a metal base plate 41 in contact with the electrical steel sheet, a cooling medium inlet / outlet 42 disposed on the metal base plate 41, a cooling medium delivery device, and a temperature sensor. The specific component connection methods can be as follows:

[0071] Drill bit 11, acting as a high-voltage electrode, is electrically connected to alternating power supply 12. By breaking the local insulation layer 62 with drill bit 11, an alternating voltage signal is applied to the metal substrate 61. Since the resistivity of the metal substrate 61 is high, significantly higher than that of good conductors (such as copper and silver), contact resistance exists between drill bit 11 and the metal substrate 61. To mitigate this contact resistance, a four-wire balancing method can be used, applying the signal to both ends of the metal substrate 61 using two drill bits 11. Microammeter 21 is electrically connected to contact electrode 22 and measures the current on contact electrode 22. Alternating power supply 12 and microammeter 21 are electrically connected to processing and control module 3. Processing and control module 3 controls alternating power supply 12 to output alternating voltage signals and controls microammeter 21 to collect current signals. Contact electrode 22 is mechanically connected to insulation layer 62. A pressure device presses contact electrode 22 onto the surface of insulation layer 62, and pressure is measured by pressure sensor 51. A metal base plate 41 is placed on the lower surface of the electrical steel sheet. It has a hollow structure in the middle and cooling medium inlet / outlet 42 on its side. A cooling medium (such as nitrogen or argon) at a constant temperature is blown into the cavity of the metal base plate 41 through a cooling medium conveying device. The temperature of the metal base plate 41 is controlled by air cooling, and the temperature of the electrical steel sheet is controlled by heat conduction. A temperature sensor is mechanically connected to the metal base plate 41 to measure the temperature of the upper surface of the metal base plate 41. Because the electrical steel sheet is thin, only 0.2–0.3 mm thick, and has high thermal conductivity, the temperature value measured by the temperature sensor in this embodiment is approximately considered to be the temperature of the insulation layer 62 of the electrical steel sheet.

[0072] The specific testing process of the aforementioned electrical steel sheet dielectric relaxation testing device can be described as follows:

[0073] Step 1: Prepare a double-sided coated electrical steel sheet to be tested, with a thickness of 0.1 to 0.3 mm and a preferred size of 100 mm (±2) * 200 mm (±5).

[0074] Step 2: Place the electrical steel sheet to be tested on the upper surface of the metal base plate 41, and perform the test using a four-wire balanced electrode structure with dual high-voltage electrodes and dual test electrodes. Place the dual drill bits 11 and dual contact electrodes 22 on the insulating layer 62 of the electrical steel sheet. The two drill bits 11 are placed at both ends of the electrical steel sheet, and the two contact electrodes 22 are placed in the middle of the electrical steel sheet, with equal spacing between the two drill bits 11 and the two contact electrodes 22. Finally, drill through the insulating layer 62 with the drill bits 11 to make an electrical connection with the metal base plate 61.

[0075] It should be noted that the drill bit size is preferably 2mm², which ensures good contact between the drill bit 11 and the metal base layer 61. The smaller area also ensures that the drill bit 11 efficiently penetrates the insulation layer 62 on the surface of the electrical steel sheet. The contact electrode 22 is preferably made of graphene-copper composite material, with a preferred size of 225mm², which is also a good conductor.

[0076] Step 3: Apply pressure to the contact electrode 22. When the pressure sensor 51 reading reaches the predetermined pressure, maintain the pressure constant.

[0077] It should be noted that a spring or hydraulic rod mounted on the upper part of the contact electrode 22 can be used as a pressure device to apply pressure to the contact electrode 22. Hydraulic pressure is preferred, as it ensures good contact between the contact electrode 22 and the insulating layer 62, reduces contact resistance, and improves test accuracy. The pressure sensor 51 reading is preferably 2000 N / m. 2 If the pressure is too low, gaps may easily appear between the contact electrode 22 and the electrical steel sheet insulation layer 62, while if the pressure is too high, the insulation layer 62 will be damaged. At this pressure, good contact between the contact electrode 22 and the electrical steel sheet insulation layer 62 can be guaranteed.

[0078] Step 4: A cooling medium at a constant temperature is introduced into the metal base plate 41. The flow rate of the cooling medium is adjustable. Once the temperature sensor displays that the temperature has reached the predetermined value T, the flow rate of the cooling medium is kept constant. At this point, the temperature of the electrical steel sheet under test and the metal base plate 41 have reached the predetermined value.

[0079] It should be noted that this step is mainly used to achieve constant temperature testing conditions, ensuring a constant ambient temperature during the testing of the electrical steel sheet. This step uses liquid nitrogen or other cooling media for temperature control, achieving testing conditions as low as -100℃, which is significantly lower than that of a constant temperature oven.

[0080] It should be noted that the preferred temperature range is -100℃ to 20℃. Using this test temperature allows for a more complete dielectric relaxation process of the studs 63 within the electrical steel sheet insulation layer 62 and the metal base layer 61, reflecting dielectric relaxation at both low and high temperatures. A wider temperature range for dielectric relaxation provides more accurate information on the structural characteristics of the studs 63 within the electrical steel sheet insulation layer 62 and the metal base layer 61.

[0081] Step 5: Simultaneously issue commands through the processing control module 3 to control the alternating power supply 12 to output a fixed-frequency alternating voltage signal V(t), and to control the microammeter 21 to collect the current signal I(t) from the contact electrode 22. The processing control module 3 can be an FPGA core board or an ARM microcontroller, preferably an FPGA core board.

[0082] It should be noted that the frequency of the alternating voltage signal output by the alternating power supply 12 is preferably 10. -4 ~10 6 The voltage waveform can be a triangular wave, sine wave, bipolar square wave, etc., preferably a sine wave, with a voltage amplitude of 0–20V. This alternating voltage signal frequency includes high frequencies (10 Hz). 6 ) and low frequency (10 -4 This ensures that the studs 63 in the electrical steel sheet insulation layer 62 and the metal base layer 61 undergo dielectric relaxation processes at different time scales, which in turn can provide richer information on the structural features of the studs 63 in the insulation layer 62 and the metal base layer 61.

[0083] Step 6: Using Fourier transform, calculate the relationship between dielectric loss tan(d) and alternating voltage signal frequency f from the acquired alternating voltage signal V(t) and current signal I(t), and plot the relationship curve of tan(d) to f to obtain the dielectric spectrum curve set.

[0084] Step 7: Change the predetermined value T in Step 4, and repeat Steps 4 to 6 for the same electrical steel sheet to obtain the relationship curves of tan(d) to f at different temperatures, thus obtaining the dielectric temperature spectrum curve set.

[0085] It should be noted that this embodiment can also be applied to scientific research by preparing multiple electrical steel sheets containing the same metal base layer 61, different insulating layers 62, and different anchoring materials 63. By repeating steps one through seven above, dielectric spectrum curves and dielectric temperature spectrum curves for different insulating layers 62 and different anchoring materials 63 can be obtained. By analyzing the influence of different anchoring materials 63 on the dielectric spectrum curves and dielectric temperature spectrum curves, the characteristic spectral range of the influence of anchoring materials 63 on the dielectric spectrum can be determined.

[0086] This embodiment makes full use of the dielectric relaxation test process, organically combining dielectric relaxation testing with the microstructure characterization of electrical steel sheets. This achieves high-precision characterization of the microstructure of the insulating layer 62 and the metal base layer 61 studs 63 on the surface of the electrical steel sheet, providing a technical foundation for the development of low-loss electrical steel sheets. This is beneficial for reducing power equipment losses. Furthermore, the dielectric relaxation test process can be automated, making the operation simple and quick, and improving operational efficiency.

[0087] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A method for testing the dielectric relaxation of electrical steel sheets, characterized in that, Includes the following steps: Set up the test environment for the electrical steel sheet and control the temperature of the electrical steel sheet to the preset temperature value; Specifically, the test environment for the electrical steel sheet is constructed based on the four-wire balancing method, and the temperature of the electrical steel sheet is controlled to a preset temperature value. This construction of the test environment based on the four-wire balancing method and control of the electrical steel sheet temperature to the preset temperature value specifically involves: constructing the test environment for the electrical steel sheet based on dual high-voltage electrodes and dual test electrodes, establishing a connection between the dual high-voltage electrodes and dual test electrodes with the electrical steel sheet at equal intervals in the order of high-voltage electrode-test electrode-high-voltage electrode-test electrode; the high-voltage electrodes are used to apply alternating voltage signals to the metal base layer of the electrical steel sheet; the test electrodes are used to collect current signals from the insulation layer. An alternating voltage signal is applied to the metal base layer of the electrical steel sheet and the current signal of the insulation layer is collected. The dielectric spectrum curve of the insulation layer of the electrical steel sheet is then calculated. By changing the applied alternating voltage signal, calculate the dielectric spectrum curves of the electrical steel sheet under different alternating voltages; Adjust the preset temperature value and calculate the dielectric temperature spectrum curves of the electrical steel sheet at different temperatures; The dielectric relaxation of electrical steel sheets was tested based on the dielectric spectrum curve set and the dielectric temperature spectrum curve set.

2. The method for testing the dielectric relaxation of electrical steel sheets according to claim 1, characterized in that, The test environment for the electrical steel sheet, based on dual high-voltage electrodes and dual test electrodes, involves establishing a connection between the dual high-voltage electrodes and dual test electrodes at equal intervals on the electrical steel sheet in a high-voltage electrode-test electrode-test electrode-high-voltage electrode sequence, including: The test electrode is connected to the electrical steel sheet by applying pressure to the test electrode.

3. A method for testing the dielectric relaxation of electrical steel sheets according to claim 1 or 2, characterized in that, The specific steps for constructing the test environment for the electrical steel sheet and controlling its temperature to a preset value are as follows: A test environment for electrical steel sheets was set up, and the temperature of the electrical steel sheets was controlled to a preset temperature value through heat conduction.

4. A dielectric relaxation testing device for electrical steel sheets, characterized in that, It includes a high-voltage electrode module, a test electrode module, a processing control module, and a temperature control module; among which: The high-voltage electrode module is used to apply an alternating voltage signal to the metal base layer of the electrical steel sheet; the test electrode module is used to collect the insulation layer current signal of the electrical steel sheet and transmit it to the processing and control module; the high-voltage electrode module and the test electrode module are used to build the test environment of the electrical steel sheet based on the four-wire balance method; specifically, the test environment of the electrical steel sheet is built based on dual high-voltage electrodes and dual test electrodes, and the dual high-voltage electrodes and dual test electrodes are connected to the electrical steel sheet at equal intervals in the order of high-voltage electrode-test electrode-test electrode-high-voltage electrode; The processing control module is used to control the high voltage electrode module to generate different alternating voltage signals and to preset the preset temperature value of the temperature control module, and to calculate the dielectric spectrum curves of the electrical steel sheet under different alternating voltages and the dielectric temperature spectrum curves of the electrical steel sheet at different temperatures. The temperature control module is used to control the temperature of the electrical steel sheet to a preset temperature value.

5. The dielectric relaxation testing device for electrical steel sheets according to claim 4, characterized in that, It also includes a pressure application module controlled by a processing control module, which is used to apply pressure to the test electrode to establish a connection between the test electrode and the electrical steel sheet.

6. A dielectric relaxation testing device for electrical steel sheets according to claim 4 or 5, characterized in that, The temperature control module controls the temperature of the electrical steel sheet to a preset temperature value through heat conduction.

Images