A method and test device for evaluating the electrical characteristics of a steeping dielectric thin film material for capacitors

Abstract

The application discloses a kind of evaluation method and test device for steepening the electrical characteristics of dielectric thin film material for capacitor, test device, including adjustable high-voltage direct-current charging unit, nanosecond pulse discharge unit, dielectric thin film material and computer measurement and control management system;Obtain the variation law of dielectric thin film material for capacitor along surface flashover breakdown characteristics with pressure gas environment, nanosecond pulse voltage rise time, repeated impact number by the experiment, obtain the variation law of dielectric thin film material body nanosecond pulse withstand voltage with nanosecond pulse power rise time, pressure gas environment by test method.The surface flashover voltage drop and body breakdown voltage drop are used as the joint criterion of the decline of dielectric thin film material insulation performance, form the evaluation method of the electrical characteristics of dielectric thin film material for capacitor, provide theoretical basis and test data support for the design of primary pulse load capacitor or steepening capacitor in high-power pulse power technology.

Description

Technical Field

[0001] This invention belongs to the field of electrical engineering technology and relates to testing and evaluation methods for the electrical properties of dielectric thin film materials, and particularly to a method and testing apparatus for evaluating the electrical properties of dielectric thin film materials for steepening capacitors. Background Technology

[0002] High-altitude electromagnetic pulse (EMP) simulators are crucial equipment for strong electromagnetic pulse (EMI) testing, and pulse compression technology is a widely used technique in large-scale EMP simulators. The design of steepening circuits is a key and core component of EMP simulators, and coaxial capacitors are the most common structural form of steepening capacitors in large-scale fast-leading-edge EMP simulators. Their withstand voltage and steepening effect are often mutually restrictive, making steepening capacitors a vulnerable link that requires attention in EMP simulators. Therefore, research on the electrical properties of dielectric thin-film materials used in steepening capacitors is of great significance for the structural design of coaxial steepening capacitors and the safe and reliable operation of large-scale fast-leading-edge EMP simulators.

[0003] In typical high-voltage, high-current generating devices, energy storage capacitors that have been charged for a long time are discharged through discharge switches, waveform forming inductors, and waveform forming resistors to generate pulse voltage and current waveforms that meet certain parameter requirements. In this state, in addition to meeting certain current carrying capacity requirements, the energy storage capacitor also needs to withstand the DC voltage of prolonged charging. However, for large-scale fast-leading-edge electromagnetic pulse simulation devices with steepening loop designs, the role of the steepening capacitor is quite different from that of the energy storage capacitor in typical high-voltage, high-current power supplies. It withstands nanosecond pulse voltages. Furthermore, because the steepening capacitor has a compact multilayer structure of "metal electrode-dielectric film-metal electrode-...metal electrode", the dielectric film material between the two electrode layers must also be subject to the risk of surface flashover.

[0004] See Figure 1a It is a first-stage pulse compression circuit for a large-scale fast-leading-edge pulse simulation device. Figure 1a In the middle, C M The main energy storage capacitor, C P To steepen the capacitance, S M and S P These are the main discharge switch and the steepening gap / switch, respectively. The steepening switch is connected to the main capacitor C. M Through the main discharge switch S M The generated primary nanosecond pulse voltage does not require the same level of energy storage as the main energy storage capacitor C. M A DC capacitor that needs to withstand prolonged charging. Steepening capacitance C. P Not only must it withstand high-amplitude nanosecond pulse voltages, but more importantly, its residual inductance, including Figure 1aAs shown, the equivalent inductance in the right mesh of the circuit should be as small as possible, which creates a technical challenge that balances the need for high voltage withstand capability and a compact structure in steepening capacitors. Figure 1b As shown, in the design of steepening capacitor structures, besides ensuring the voltage withstand capability of the capacitor film material meets the rated voltage of large-scale fast-leading-edge electromagnetic pulse (EMP) simulators, the surface flashover tolerance of the dielectric film material between each electrode layer of the steepening capacitor becomes the dominant failure mode for the steepening capacitor and even the entire EMP simulator. This is because the three junctions of the two electrodes, the dielectric film, and the gas environment in which the steepening capacitor operates form the point where the electric field of the steepening capacitor is most prone to distortion. Once a permanent conductive path is formed by surface flashover, the steepening capacitor and the fast-leading-edge EMP simulator will fail, the output fast-leading-edge pulse will be distorted, and the EMP system may even lose its functionality.

[0005] Therefore, in response to the significant demand for large-scale fast nanosecond electromagnetic pulse simulation devices, it is crucial to investigate the influence of the surface flashover characteristics of dielectric thin film materials for steepening capacitors on the surface insulation withstand voltage and the bulk withstand voltage of the thin film material, and to screen out the dielectric thin film material with the best overall performance. The research on dielectric thin film materials for steepening capacitors, as well as the optimized design and performance improvement of steepening capacitors, are urgent problems to be solved. Summary of the Invention

[0006] The purpose of this invention is to propose an evaluation method and test apparatus for the electrical properties of dielectric thin film materials for steepening capacitors, so as to screen out dielectric thin film materials with the best comprehensive performance, and provide technical support for the research of dielectric thin film materials for steepening capacitors, as well as the optimized design and performance improvement of steepening capacitors.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] An electrical characteristic testing device for dielectric thin film materials used in steepening capacitors includes an adjustable high-voltage DC charging unit, a nanosecond pulse discharge unit, dielectric thin film materials, and a computer measurement and control management system.

[0009] The adjustable high-voltage DC charging unit consists of an adjustable high-voltage DC charging power supply, a current-limiting resistor, and a DC voltage divider, used to charge the energy storage capacitor C1 of the nanosecond pulse discharge unit. The nanosecond pulse discharge unit includes the energy storage capacitor C1, a discharge switch G, waveform forming resistors Rf and Rt, and a waveform forming capacitor C2. The adjustable high-voltage DC charging unit charges the energy storage capacitor C1 of the nanosecond pulse discharge unit. The electrical energy stored in the energy storage capacitor C1 is discharged through the waveform forming resistors Rf and Rt and the waveform forming capacitor C2 when the discharge switch G is triggered and transiently turned on. The generated nanosecond pulse voltage is applied between two points on the surface of the dielectric film material under test that are a certain insulating distance apart, or applied to the upper and lower surfaces of the dielectric film material under test at the same location. During the test, the dielectric film material under test is fixed in a sealed insulating shell filled with insulating gas by a test fixture.

[0010] The computer-based measurement and control management system is used for the measurement and control management of nanosecond impulse voltage withstand tests on dielectric thin film materials, including process control of the withstand voltage test and analysis, processing and management of test data and waveforms.

[0011] Furthermore, the computer-based measurement and control management system includes a control unit, a pulse voltage divider, an oscilloscope, and a computer;

[0012] The computer and control unit communicate via optical fiber, and the computer and oscilloscope transmit data via Ethernet port. The surface flashover breakdown voltage and body withstand voltage of the tested dielectric thin film material are extracted by a pulse voltage divider, acquired and recorded by the oscilloscope, and the electrical properties of the dielectric thin film material are tested and evaluated through data communication between the computer and the oscilloscope.

[0013] Furthermore, the waveform forming resistors Rf and Rt, as well as the waveform forming capacitor C2, are components with discretely adjustable parameters. By adjusting the rise time of the nanosecond pulse voltage, the test requirements for the rise time of different nanosecond pulse voltages of different dielectric thin film materials for steepening capacitors can be met.

[0014] Furthermore, two "finger-shaped electrodes" are respectively connected to the high-voltage end and low-voltage end of the nanosecond pulse discharge unit, and the two "finger-shaped electrodes" are set at two points with a certain insulation distance on the surface of the dielectric thin film material to conduct a surface flashover characteristic test of the dielectric thin film material; or two "circular" or "elliptical" electrodes are respectively set on the upper and lower surfaces of the dielectric thin film material at the same position to conduct a bulk breakdown withstand test of the material body.

[0015] Furthermore, the sealed insulating shell is filled with 0.1-1 MPa of N2 or SF6 gas.

[0016] A method for evaluating the electrical properties of dielectric thin film materials for steepening capacitors includes the following steps:

[0017] 1) The adjustable high voltage DC charging unit automatically controls the charging voltage of the energy storage capacitor C1 in the nanosecond pulse discharge unit. During the impact test, the charging voltage of the energy storage capacitor C1 increases stepwise until the tested dielectric film material undergoes surface flashover breakdown discharge or bulk breakdown. The maximum value of the nanosecond pulse voltage across the tested dielectric film material is recorded as the initial surface flashover breakdown voltage or initial bulk breakdown voltage of the tested dielectric film material.

[0018] 2) Apply a nanosecond pulse voltage between the upper and lower surfaces of the dielectric thin film material, adjust the rise time of the nanosecond pulse voltage, and obtain the relationship between the bulk breakdown withstand voltage of the dielectric thin film material and the gas pressure and the rise time of the nanosecond pulse; or apply a nanosecond pulse voltage between two points a certain distance apart on the surface of the dielectric thin film material, adjust the rise time of the nanosecond pulse voltage, and obtain the relationship between the surface flashover breakdown voltage of the dielectric thin film material and the gas pressure and the rise time of the nanosecond pulse.

[0019] 3) The charging voltage of the energy storage capacitor C1 in the nanosecond pulse discharge unit is not less than the surface flashover breakdown voltage of the tested dielectric thin film material. A repeatable test of the surface flashover breakdown of the dielectric thin film material is carried out. During the repeated surface flashover breakdown test, the volume breakdown withstand voltage of the dielectric thin film material is measured at regular intervals. During the repeatable nanosecond pulse electrical characteristic test of the dielectric thin film material, if the surface flashover breakdown voltage or the volume breakdown withstand voltage of the dielectric thin film material drops to 10% or 20% of the initial surface flashover breakdown voltage or the initial volume breakdown voltage, the life of the dielectric thin film material is considered to have ended.

[0020] This invention relates to a method and testing apparatus for evaluating the electrical properties of dielectric thin film materials used in steepening capacitors. Based on the operating scenario of steepening capacitors in a pulsed power system, a test circuit for steepening capacitors undergoing nanosecond pulse discharge is established. The testing apparatus includes an adjustable high-voltage DC charging unit, a nanosecond pulse discharge unit, dielectric thin film materials, and a computer-based measurement and control management system. The adjustable high-voltage DC charging unit charges the nanosecond pulse discharge unit. The nanosecond pulse discharge generates a nanosecond pulse voltage applied between two points on the surface of the dielectric thin film material under test, separated by a certain insulation distance, or applied to the upper and lower surfaces of the dielectric thin film material at the same location. During the test, the dielectric thin film material under test is fixed in a sealed insulating shell filled with insulating gas by a test fixture. The computer-based measurement and control management system is used for the measurement and control management of the nanosecond impulse voltage withstand test of the dielectric thin film material, including process control of the withstand voltage test and analysis, processing, and management of test data and waveforms.

[0021] This experiment revealed the variation of the surface flashover breakdown characteristics of dielectric thin film materials for steepening capacitors with varying pressure gas environment, rise time of nanosecond pulse voltage, and number of repeated impacts. Simultaneously, the variation of the nanosecond pulse withstand voltage of the dielectric thin film material itself with rise time of the nanosecond pulse power supply and pressure gas environment was experimentally determined. By using the surface flashover voltage drop and the bulk breakdown voltage drop as a joint criterion for the degradation of the insulation performance of the dielectric thin film material, a method for evaluating the electrical characteristics of dielectric thin film materials for steepening capacitors was developed. This provides a theoretical basis and experimental data support for the design of primary pulse load capacitors or steepening capacitors in high-power pulsed power technology. It also provides technical support for the formulation and process research of dielectric thin film materials for steepening capacitors, as well as the structural design and engineering applications of steepening capacitors. Attached Figure Description

[0022] Figure 1a A circuit diagram of a first-stage pulse compression device for a large-scale fast leading-edge pulse simulation device;

[0023] Figure 1b This is a schematic diagram of the steepening capacitor.

[0024] Figure 2 This is a schematic diagram of the electrical characteristic testing device for dielectric thin film materials used in the present invention for steepening capacitance;

[0025] Figure 3a This is a schematic diagram of the electrode clamping method for a surface flashover withstand test of dielectric thin film materials;

[0026] Figure 3b This is a schematic diagram of the electrode clamping method for bulk breakdown withstand testing of dielectric thin film materials;

[0027] Figure 4 This is a flowchart of the test method for the initial electrical characteristics of dielectric thin film materials used in steepening capacitors according to the present invention;

[0028] Figure 5 This is a flowchart of the test method for repeated surface flashover characteristics of dielectric thin film materials used in steepening capacitors according to the present invention.

[0029] Figure 6 This is a voltage waveform diagram at both ends when the dielectric surface of the dielectric thin film material of the present invention is damaged by breakdown during the nanosecond pulse voltage test.

[0030] In the diagram: 1-Adjustable high-voltage DC charging unit, 1-1-Adjustable high-voltage DC charging power supply, 1-2 Current limiting resistor, 1-3-DC voltage divider, 2-Nanosecond pulse discharge unit, 3-Dielectric thin film material, 4-Computer measurement and control management system, 41-Control unit, 42-Pulse voltage divider, 43-Oscilloscope, 44-Computer, LV-Low-voltage electrode, HV-High-voltage electrode. Detailed Implementation

[0031] The present invention will be further described in detail below with reference to specific embodiments, but this is not intended to limit the present invention.

[0032] See Figure 2 The experimental apparatus for steepening the electrical properties of dielectric thin film materials for capacitors according to the present invention consists of an adjustable high voltage DC charging unit 1, a nanosecond pulse discharge unit 2, a dielectric thin film material 3, and a computer measurement and control management system 4.

[0033] The adjustable high-voltage DC charging unit 1 mainly consists of an adjustable high-voltage DC charging power supply 1-1, a current-limiting resistor 1-2, and a DC voltage divider 1-3. Its function is to charge the energy storage capacitor C1 of the nanosecond pulse discharge unit 2. Its output voltage can be set on the human-machine interface of the adjustable high-voltage DC charging power supply 1-1, or it can be set and controlled through the computer measurement and control management system 4. The nanosecond pulse discharge unit 2 mainly includes an energy storage capacitor C1, a discharge switch G, waveform forming resistors Rf and Rt, and a waveform forming capacitor C2. Its main feature is that the waveform forming resistors Rf, Rt, and waveform forming capacitor C2 are discretely adjustable components, which can adjust the rise time of the nanosecond pulse voltage to meet the test requirements of different nanosecond pulse voltage rise times for different dielectric thin film materials used in steepening capacitors.

[0034] like Figure 2 As shown, in the nanosecond pulse discharge unit 2, the high-voltage terminal of the energy storage capacitor C1 is electrically connected to the high-voltage terminal of the discharge switch G. The low-voltage terminal of the discharge switch G is connected to one end of the waveform forming resistors Rf and Rt. The other end of the waveform forming resistor Rt is connected to the low-voltage terminal of the energy storage capacitor C1. The other end of the waveform forming resistor Rf is electrically connected to one end of the waveform forming capacitor C2. The other end of the waveform forming capacitor C2 is electrically connected to the low-voltage terminal of the energy storage capacitor C1.

[0035] The adjustable high-voltage DC charging unit 1 charges the energy storage capacitor C1 of the nanosecond pulse discharge unit 2; then, the energy stored in the energy storage capacitor C1 is discharged through the waveform forming resistors Rf and Rt and the waveform forming capacitor C2 under the transient conduction triggered by the discharge switch G, and the generated nanosecond pulse voltage is applied to both ends of the test dielectric thin film material 3 with a certain surface distance, or to the upper and lower surfaces of the dielectric thin film material 3.

[0036] During the test, the dielectric thin film material 3 is fixed in a sealed insulating shell by a test fixture. The sealed shell is filled with an insulating gas at 0.1-1 MPa, which can be N2 or SF6, etc. Nanosecond pulses can be applied to the surface of the dielectric thin film material 3 with a certain insulating distance through electrodes to conduct a surface flashover withstand test of the insulating material; or they can be applied between the upper and lower surfaces of the dielectric thin film material 3 under test to conduct a bulk breakdown withstand test of the material.

[0037] The computer-controlled measurement and control management system 4 mainly consists of a control unit 41, a pulse voltage divider 42, an oscilloscope 43, and a computer 44. The computer 44 communicates with the control unit 41 via fiber optic transmission, and the computer 44 communicates with the oscilloscope 43 via Ethernet output. This system enables both electromagnetic compatibility in strong pulse electromagnetic environments and rapid control and data transmission. The main functions of the computer-controlled measurement and control management system 4 include: ① automatically monitoring the charging process of the nanosecond pulse voltage test; ② automatically controlling the process of the nanosecond pulse voltage withstand test of the dielectric thin film material 3 in conjunction with the computer; ③ analyzing and judging the results of the nanosecond pulse withstand (including surface flashover withstand and bulk breakdown withstand) tests of the dielectric thin film material 3; ④ extracting, recording, storing, querying, and outputting test reports for the nanosecond pulse withstand voltage test signals of the dielectric thin film material.

[0038] The measurement and control management of the nanosecond impulse voltage withstand test of the dielectric thin film material 3 is carried out by the computer measurement and control management system 4, which performs process control of the withstand voltage test and analysis, processing and management of test data and waveforms. The surface flashover breakdown voltage and the body withstand voltage of the tested dielectric thin film material 3 are extracted by the pulse voltage divider 42, acquired and recorded by the oscilloscope 43, and the electrical characteristics of the dielectric thin film material 3 are evaluated through data communication between the computer 44 and the oscilloscope 43. Through the analysis of the computer management software, the process control of the nanosecond pulse voltage test of the dielectric thin film material 3 can be realized, and the test criteria, the maximum surface flashover and body nanosecond withstand voltage values ​​that the dielectric thin film material 3 can withstand, and the number of nanosecond pulse surface flashovers that the dielectric thin film material for steepening capacitor can withstand are provided.

[0039] The nanosecond pulse voltage applied across the dielectric thin film material 3 is extracted and recorded by the pulse voltage divider 42 and the oscilloscope 43. Data communication between the computer 404 and the oscilloscope 43 enables the experimental control and data processing of the nanosecond pulse power supply characteristics of the dielectric thin film material. Therefore, it can be concluded that the nanosecond pulse voltage testing device for dielectric thin film materials includes multiple functions such as high-voltage charging, nanosecond pulse discharging, measurement, and management, and can perform electrical characteristic testing and performance evaluation on different dielectric thin film materials used for steepening capacitors.

[0040] See Figure 3a , Figure 3b The electrical characteristic tests for dielectric thin film materials used in steepening capacitors include surface flashover withstand tests and bulk breakdown withstand tests. Figure 3aTwo "finger electrodes" are provided on the surface of the dielectric thin film material 3 shown, which are respectively connected to the high voltage end and the low voltage end of the nanosecond pulse discharge unit 2. The surface flashover characteristics test of the dielectric thin film material 3 can be carried out, and the surface flashover distance of the dielectric thin film material between the two "finger electrodes" can be adjusted. Figure 3b Two "circular" or "elliptical" electrodes are provided on the upper and lower surfaces of the dielectric thin film material 3 shown, which are respectively connected to the high-voltage end and low-voltage end of the nanosecond pulse voltage discharge unit, so that the bulk breakdown withstand voltage test of the dielectric thin film material 3 can be carried out. Figure 3a , Figure 3b The dielectric thin film material and its electrode structure shown are encapsulated in a sealed insulating shell, which can be filled with gas such as SF6, with a pressure range of 0.1MPa-1.0MPa.

[0041] Meanwhile, dielectric film materials include at least commonly used polypropylene (PP) film materials and polyester (PET) film materials. By analyzing the electrical properties of different dielectric film materials, and combining the nanosecond pulse surface flashover characteristics and bulk nanosecond pulse tolerance characteristics of dielectric film materials, an evaluation method for the electrical properties of dielectric film materials suitable for steepening capacitors in pulse power supplies is formed.

[0042] See Figure 4 , Figure 5 The measurement and control process for the initial electrical characteristic test of dielectric thin film materials used to steepen capacitance is as follows:

[0043] (1) Set the test conditions for the initial electrical properties of the dielectric thin film material on the computer human-computer interaction interface of the nanosecond pulse voltage test device, including the gas type and gas pressure, the dielectric material type (such as PP film or PET film, etc.), the initial value of the charging (or discharging) voltage and the step voltage (the voltage difference of the charging voltage increase in each test), etc.

[0044] (2) Start the computer management software for the nanosecond pulse voltage test.

[0045] (3) The computer and control circuit work together to control the charging and discharging process of the nanosecond pulse discharge circuit according to the preset initial value of the charging voltage and the step voltage value.

[0046] (4) The voltage signal acting on both ends of the dielectric thin film material 3 under test is extracted and recorded by the pulse voltage divider 42 and the oscilloscope 43, and transmitted through the network output between the computer 44 and the oscilloscope 43 to process and analyze the test results.

[0047] (5) If the dielectric thin film material does not experience surface flashover breakdown, the charging voltage is increased by a step voltage and the test continues until the dielectric thin film material 3 experiences surface flashover breakdown. The voltage waveform of the flashover breakdown is shown in [reference needed]. Figure 6 As shown.

[0048] (6) The initial surface flashover withstand voltage of the dielectric thin film material is the maximum value of the nanosecond pulse voltage at both ends of the dielectric thin film when surface flashover does not occur.

[0049] (7) By changing different types of dielectric thin film materials, gas pressure environment and the path distance of surface flashover, the relationship between the initial surface flashover withstand voltage of different dielectric thin film materials and gas pressure and surface flashover distance can be obtained.

[0050] Using the same test procedure as for the initial surface flashover withstand voltage of dielectric thin film material 3, but changing the application method of the nanosecond pulse voltage, the nanosecond pulse voltage is applied to the upper and lower surfaces of the dielectric thin film material to obtain the initial bulk breakdown voltage of the dielectric thin film material. Both the initial surface flashover withstand voltage and the initial bulk breakdown withstand voltage are tested on the new dielectric thin film material.

[0051] See Figure 5 , Figure 6 The measurement and control process for the repeated surface flashover characteristic test of the dielectric thin film material used for steepening capacitor lifetime characteristics is as follows:

[0052] (1) On the computer human-computer interaction interface of the nanosecond pulse voltage test device, set the test conditions for the repeated surface flashover characteristics of the dielectric thin film material lifetime characteristics, including gas type and gas pressure, dielectric material type (such as PP film or PET film, etc.), charging (or discharging) voltage, number of tests for each group of repeated surface flashover discharge (i.e., how many times the dielectric thin film material undergoes surface flashover test before the bulk breakdown voltage of the dielectric thin film material needs to be measured), the surface flashover voltage drop of dielectric thin film material 3 (e.g., 10% or 20%) and the bulk breakdown voltage drop (e.g., 10% or 20%), etc.

[0053] (2) Start the computer management software for the nanosecond pulse voltage test.

[0054] (3) The computer and control circuit work together to control the repeated charging and discharging process of the nanosecond pulse discharge circuit according to the preset charging voltage.

[0055] (4) In each nanosecond impact test, the voltage signal across the test dielectric thin film material 3 is extracted and recorded by the pulse voltage divider 42 and the oscilloscope 43, and the test results are processed and analyzed by the network data transmission between the computer 44 and the oscilloscope 43.

[0056] (5) If the voltage reduction rate between two points along the surface flashover path of the dielectric thin film material 3 does not exceed the preset voltage drop amplitude, the repeated charging and discharging process continues until the number of surface flashover tests of the dielectric thin film material 3 meets the preset number of repeated surface flashover discharge tests for each group.

[0057] (6) Measure the bulk breakdown voltage of dielectric thin film materials.

[0058] (7) If the reduction rate of the bulk breakdown voltage of the two surfaces of the dielectric thin film material 3 from the initial bulk breakdown voltage does not exceed the preset voltage drop amplitude, then repeat process (3) to (6) to continue the test.

[0059] (8) Until, during repeated testing, the rate of decrease of the voltage between two points along the surface flashover path of the dielectric thin film material 3 and the initial surface flashover withstand voltage exceeds the preset voltage drop range, or the rate of decrease of the bulk breakdown voltage of the two surfaces of the dielectric thin film material 3 and the initial bulk breakdown voltage exceeds the preset voltage drop range.

[0060] (9) Through computer data processing and analysis, the total number of impact nanosecond pulse surface flashover tests that the reduction rate of the dielectric film's surface flashover withstand voltage does not exceed the preset voltage drop amplitude, and the total number of repeated nanosecond pulse surface flashover tests that the reduction rate of the dielectric film's bulk breakdown withstand voltage does not exceed the preset voltage drop amplitude, are obtained. The smaller of the two cases is the surface flashover lifetime of the dielectric film material.

Claims

1. A method for evaluating the electrical properties of dielectric thin film materials for steepening capacitors, characterized in that: The experimental setup used includes an adjustable high-voltage DC charging unit (1), a nanosecond pulse discharge unit (2), a dielectric thin film material (3), and a computer measurement and control management system (4). The adjustable high-voltage DC charging unit (1) consists of an adjustable high-voltage DC charging power supply (1-1), a current-limiting resistor (1-2), and a DC voltage divider (1-3), used to charge the energy storage capacitor C1 of the nanosecond pulse discharge unit (2); the nanosecond pulse discharge unit (2) includes an energy storage capacitor C1, a discharge switch G, waveform forming resistors Rf and Rt, and a waveform forming capacitor C2. The adjustable high-voltage DC charging unit (1) charges the energy storage capacitor C1 of the nanosecond pulse discharge unit (2). The electrical energy stored in the energy storage capacitor C1 is discharged through the waveform forming resistors Rf and Rt and the waveform forming capacitor C2 under the transient conduction triggered by the discharge switch G. The generated nanosecond pulse voltage is applied between two points on the surface of the dielectric film material (3) that are a certain insulating distance apart, or applied to the upper and lower surfaces of the dielectric film material (3) at the same position; during the test, the dielectric film material (3) is fixed in a sealed insulating shell filled with insulating gas by the test fixture; The computer measurement and control management system (4) is used for the measurement and control management of the nanosecond impulse voltage withstand test of dielectric thin film material (3), and to carry out the process control of the withstand voltage test as well as the analysis, processing and management of test data and waveforms; The computer measurement and control management system (4) includes a control unit (41), a pulse voltage divider (42), an oscilloscope (43), and a computer (44). The computer (44) and the control unit (41) communicate via optical fiber. The computer (44) and the oscilloscope (43) transmit data via network port. The surface flashover breakdown voltage and the body withstand voltage of the dielectric thin film material (3) under test are extracted by the pulse voltage divider (42), collected and recorded by the oscilloscope (43), and the electrical characteristics of the dielectric thin film material (3) are tested and evaluated through data communication between the computer (44) and the oscilloscope (43). The evaluation method includes the following steps: 1) Adjustable high-voltage DC charging unit (1) for the energy storage capacitor in nanosecond pulse discharge unit (2) C The charging voltage of 1 is automatically controlled, and the energy storage capacitor is used during the impact test. C The charging voltage of 1 is increased stepwise until the tested dielectric film material (3) undergoes surface flashover breakdown discharge or body breakdown. The maximum value of the nanosecond pulse voltage at both ends of the tested dielectric film material (3) during the test is recorded as the initial surface flashover breakdown voltage or the initial body breakdown voltage of the tested dielectric film material (3). 2) Apply a nanosecond pulse voltage between the upper and lower surfaces of the dielectric thin film material (3), adjust the rise time of the nanosecond pulse voltage, and obtain the relationship between the bulk breakdown withstand voltage of the dielectric thin film material (3) and the gas pressure and the rise time of the nanosecond pulse; or apply a nanosecond pulse voltage between two points a certain distance apart on the surface of the dielectric thin film material (3), adjust the rise time of the nanosecond pulse voltage, and obtain the relationship between the surface flashover breakdown voltage of the dielectric thin film material (3) and the gas pressure and the rise time of the nanosecond pulse. 3) Energy storage capacitor in nanosecond pulse discharge unit (2) C Under a charging voltage not less than the surface flashover breakdown voltage of the tested dielectric film material (3), a repeatability test of the surface flashover breakdown of the dielectric film material (3) is conducted. During the repeatability test of the surface flashover breakdown, the volume breakdown withstand voltage of the dielectric film material (3) is measured after a certain number of repeated surface flashover discharge tests. During the repeatability test of the dielectric film material (3) of the nanosecond pulse electrical characteristics, if the surface flashover breakdown voltage or the volume breakdown withstand voltage of the dielectric film material (3) drops to 10% or 20% of the initial surface flashover breakdown voltage or the initial volume breakdown voltage, the life of the dielectric film material (3) is considered to have ended.

2. The method for evaluating the electrical properties of dielectric thin film materials for steepening capacitors as described in claim 1, characterized in that: The waveform forming resistors Rf and Rt, and the waveform forming capacitor C2 are components with discretely adjustable parameters. By adjusting the rise time of the nanosecond pulse voltage, the test requirements for the rise time of different nanosecond pulse voltages of different dielectric thin film materials for steepening capacitors can be met.

3. The method for evaluating the electrical properties of dielectric thin film materials for steepening capacitors as described in claim 1 or 2, characterized in that: Two finger electrodes are connected to the high-voltage end and low-voltage end of the nanosecond pulse discharge unit (2) respectively, and the two finger electrodes are set at two points with a certain insulation distance on the surface of the dielectric thin film material (3) to conduct the surface flashover characteristic test of the dielectric thin film material (3); or two circular or elliptical electrodes are set on the upper and lower surfaces of the dielectric thin film material (3) at the same position to conduct the bulk breakdown withstand test of the material body.

4. The method for evaluating the electrical properties of dielectric thin film materials for steepening capacitors as described in claim 3, characterized in that: The sealed insulating shell is filled with 0.1-1 MPa of N2 or SF6 gas.

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