Insulating material trap characteristic characterization method

Abstract

The invention belongs to the technical field of electrical equipment and electrical engineering, and particularly relates to an insulating material trap characteristic characterization method. The invention aims to solve the problems of large current data fluctuation and easy interference of the existing thermal stimulation current method, and the problem that the surface potential attenuation method only reflects surface and near-surface charges and is low in deep sensitivity. The method comprises the following steps: carrying out polarization and depolarization on an insulating material, collecting polarization instantaneous charges, attenuation initial charges and termination charges through a DCIC-Q (t) system, and obtaining a depolarization charge quantity attenuation curve; constructing a space charge limited current theoretical model without polarization characteristics, and calculating intrinsic carrier mobility under different polarization electric fields; the electric field influence is corrected in combination with the Pole-Frenkel law, trap level distribution is obtained, and dissipated charges and non-escaped charges are distinguished through a charge difference value. According to the method, the data stability and the deep charge sensitivity are improved, and the trap characteristic of the insulating material is accurately represented.

Description

Technical Field

[0001] This invention belongs to the field of electrical equipment and electrical engineering technology, and specifically relates to a method for characterizing the trap properties of insulating materials. Background Technology

[0002] In semiconductors and insulating materials, trap properties determine the space charge distribution, affect DC conductivity, and influence DC breakdown characteristics. Traps capture free electrons or holes, forming localized charge centers, thereby affecting the mobility of electrons or holes. Based on different mechanisms of regulating charge transport and breakdown behavior, traps can be classified into shallow traps and deep traps according to their energy levels. Shallow traps can assist charge carrier conduction in the dielectric, while deep traps can capture charge carriers, restricting their transport in the dielectric.

[0003] Extensive research has been conducted on the trapping characteristics of insulating materials. The Thermally Stimulated Current (TSC) method heats the sample to excite and release trapped charges, measuring the resulting depolarization current to analyze parameters such as trap energy levels and density. However, the current data obtained by TSC fluctuates significantly and is easily affected by external conditions. The Surface Potential Decay (SPD) method injects charges (such as corona discharge or electron radiation) onto the material surface and measures the decay of the surface potential over time to infer charge migration and trapping characteristics. However, SPD only reflects the charge behavior of the surface or near-surface region and has low sensitivity to deep charges. Summary of the Invention

[0004] This invention provides a method for characterizing the trap properties of insulating materials, in order to solve the technical problems of existing methods for studying the trap properties of insulating materials, such as the thermal stimulation current method which has large fluctuations in current data and is easily affected by external conditions, and the surface potential decay method which can only reflect the charge behavior of the material surface or near-surface region and has low sensitivity to deep charge.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A method for characterizing the trap properties of insulating materials includes the following steps: The insulating material is polarized, and then depolarized after a period of polarization. The instantaneous charging charge generated during the polarization of the insulating material is collected. Q 0. The amount of charge that begins to decay after polarization is complete. Q ini and the amount of termination charge at termination Q end The depolarization charge decay curve of the insulating material was obtained. Using a pre-constructed, optimized space charge-limited current theoretical model for removing polarization characteristics, the depolarization charge decay curve of the insulating material is analyzed, and the intrinsic carrier mobility of the insulating material under different polarization electric fields is calculated. μ(t ); Based on the intrinsic carrier mobility of insulating materials under different polarized electric fields μ(t The Poole-Frenkel law was used to correct for the influence of the electric field, and the trap energy level distribution was obtained. .

[0006] The polarization period of the insulating material is specifically: through current integration of charge technology, in DCIC- Q (t) Under the test system conditions of 1~20kV, a voltage is output to the insulating material to polarize it. The polarization voltage is set to 1~20 kV, and the polarization time is 180~600 s. DCIC- Q (t) The sampling step size of the device is 1~2s.

[0007] The depolarization time is 600~3000 s, DCIC- Q (t) The sampling step size of the device is 1~2 s.

[0008] The expression for the space charge confinement current theoretical model optimized by polarization characteristics is as follows:

[0009] In the formula, J Current density; e 0 is the vacuum permittivity. e r The relative permittivity, m Carrier mobility; E and d These represent the electric field and thickness of the insulating material, respectively. i These are the trap control parameters.

[0010] The calculation of the intrinsic carrier mobility of the insulating material under different polarized electric fields. μ(t The intrinsic carrier mobility of insulating materials under different polarized electric fields. μ(t The calculation formula is as follows:

[0011] In the formula, q ( t ) represents charge density, and represents charge quantity. Q ( t The ratio of the volume of the sample to the volume of the test sample. e 0 is the vacuum permittivity. e r is the relative permittivity.

[0012] The intrinsic carrier mobility of insulating materials under different polarized electric fields is used as a basis. μ(t The Poole-Frenkel law was used to correct for the influence of the electric field, and the trap energy level distribution was obtained. Specifically, this involves correcting the effect of the electric field using the Poole–Frenkel law to adjust the trap energy level distribution. The calculation expression is:

[0013] in, k Boltzmann's constant, T Thermodynamic temperature; v For escape frequency, R The average distance of the local states. e The amount of electron charge. E For the electric field of the insulating material, e 0 is the vacuum permittivity. e 0 is the relative permittivity.

[0014] Through the trap energy level distribution The relationship between trap energy levels and carrier mobility was obtained. Since carrier mobility is related to depolarization time, the calculated trap energy level distribution was thus obtained. For a given range, the instantaneous charging charge generated at the moment of polarization of the insulating material is considered. Q 0. The amount of charge that begins to decay after polarization is complete. Q ini and the amount of termination charge at termination Q end The charge is determined to be either a dissipated charge or a charge that has not yet escaped.

[0015] Termination charge at termination Q end The amount of charge that begins to decay after polarization is complete Q ini There is a difference The difference can characterize the amount of charge dissipated, that is, represent the trap energy level distribution. The amount of charge stored within the energy level range, and the termination charge at termination. Q end The amount of charge that begins to decay after polarization is complete Q ini The difference between The expression is: .

[0016] Termination charge at termination Q endInstantaneous charging charge generated at the moment of polarization with insulating material Q There is a difference between 0 and 0. The difference can characterize the amount of charge that has not yet escaped, and the amount of charge that has not yet escaped represents the energy level distribution above the trap. The deeper trap energy level, the termination charge at termination. Q end Instantaneous charging charge generated at the moment of polarization with insulating material Q The expression for the difference between 0 and 0 is: .

[0017] The DCIC-Q(t) test system includes a PC and a DCIC- Q (t) The equipment and three-electrode system, on the PC side, are connected to a communication device to control the voltage output of the high-voltage source, and on the other hand, they are connected to a DCIC via optical fiber. Q (t) Device, acquiring charge information of insulating material placed in a three-electrode system; DCIC- Q (t) The device is connected to a high-voltage source, outputs voltage to the insulating material, and transmits the test data back to the PC via optical fiber. The insulating material is placed in the three-electrode system for polarization, and then the voltage is removed to depolarize it. The depolarization charge decay curve of the insulating material is obtained. After the test is completed, the DCIC-Q(t) device, the insulating material and the three-electrode system are discharged to eliminate residual charge.

[0018] Compared with the prior art, the present invention has the following beneficial effects: This invention proposes a method for characterizing the trapping characteristics of insulating materials. A DCICQ(t) test system using current-integrated charge technology is employed. This system measures a polarization voltage of 1 to 20 kV, a polarization time of 180 to 600 seconds, a depolarization time of 600 to 3000 seconds, and a sampling step size of 1 to 2 seconds to test the polarization and depolarization processes of the insulating material. Simultaneously, it acquires the instantaneous charging charge generated during polarization. Q The amount of charge that begins to decay after 0 polarization is complete Q ini and the amount of termination charge at termination Q end The technique of constructing depolarization charge decay curves, compared to the direct acquisition of current data by the thermal stimulation current method, transforms the current into charge integrals through current integration, which can smooth instantaneous current fluctuations, significantly reducing data volatility. Fixed key test parameters reduce interference from external conditions such as voltage instability and improper sampling intervals, improving the stability and repeatability of test data. Furthermore, the multi-stage charge parameters cover the entire polarization cycle, from instantaneous charging to the termination of decay, providing comprehensive charge behavior support for subsequent trap characteristic analysis and avoiding the limitation that a single parameter cannot reflect the overall characteristics.

[0019] Furthermore, this invention constructs a space charge confinement current theoretical model optimized for polarization characteristics. Based on the depolarization charge decay curve, it calculates the intrinsic carrier mobility under different polarization electric fields using a specific formula, thus eliminating the interference of polarization characteristics on core parameters. Existing space charge confinement current models are easily affected by the polarization characteristics of materials, leading to deviations in carrier mobility calculations and affecting the accuracy of trap characteristic analysis. This invention optimizes the model to remove polarization factors, making the calculated intrinsic carrier mobility more consistent with the true characteristics of the material, providing reliable core parameters for subsequent derivation of trap energy level distribution.

[0020] Furthermore, by utilizing Poole-Frenkel's law to correct the effect of the electric field on carrier mobility, the trap energy level distribution was derived. Simultaneously, the dissipated charge within the trap energy level range and the unescaped charge in deeper trap energy levels were characterized. Addressing the limitation that the surface potential decay method can only reflect surface or near-surface charges, the true trap energy level distribution was obtained through electric field correction. Charge difference analysis was used to distinguish trap charges at different depths, achieving a comprehensive characterization of surface, near-surface, and deep traps. This significantly improved the sensitivity to deep charges, overcoming the detection range limitations of existing methods. Furthermore, a quantitative correlation between trap energy levels and carrier mobility / depolarization time was established, clarifying the range of trap energy level distribution. This represents an upgrade from qualitative description to quantitative characterization, improving the accuracy of trap property research in insulating materials.

[0021] Furthermore, by adopting an architecture of PC-based DCICQ(t) equipment and a three-electrode system, data is transmitted via optical fiber to reduce electromagnetic interference. After testing, the equipment materials and electrode system are discharged to eliminate residual charge. In this technical approach, the optical fiber transmission method reduces the impact of electromagnetic interference on data acquisition, the three-electrode system improves the stability of the polarization process, further enhances the anti-interference capability, and the discharge treatment after testing avoids the interference of residual charge on subsequent tests, ensuring the consistency of multiple tests and providing technical support for the reproducibility of experimental data. Attached Figure Description

[0022] Figure 1 DCIC- in the embodiments of the present invention Q (t) Wiring diagram of the test system; Figure 2 The figures show the polarization and depolarization charge curves of insulating sample A and insulating sample B under a test electric field of 30 kV / mm in this embodiment of the invention. Figure 3 This diagram illustrates the method for calculating the amount of charge stored in different energy level ranges in an embodiment of the present invention. Figure 4 This is a diagram showing the amount of charge stored in different energy level ranges of insulating sample A and insulating sample B under a 30 kV / mm polarized electric field in an embodiment of the present invention. Figure 5 The diagram shows the trap energy level distribution of insulating sample A and insulating sample B under a 30 kV / mm polarized electric field in this embodiment of the invention. Figure 6 This is a flowchart illustrating a method for characterizing the trap properties of insulating materials according to the present invention. Detailed Implementation

[0023] To further understand the content of this invention, the invention will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the embodiments are merely illustrative and not limiting of the invention.

[0024] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0025] This embodiment proposes a method for characterizing the trap properties of insulating materials, such as... Figure 6 As shown, based on DCIC- Q The test system (t) uses current-integrated charge technology to polarize the insulating material under 1~20kV conditions, then removes the electric field to obtain the charge decay curve of XLCP over time. A space charge confinement current theoretical model optimized for polarization characteristics is established, and the Poole–Frenkel law is introduced to correct for the influence of the electric field. The test procedure of this invention obtains data characterizing the trap properties, such as carrier mobility, trap depth distribution, and deep trap charge. Specifically, it includes the following steps: The insulating material is polarized for a period of time, followed by depolarization, and the instantaneous charging charge generated during the polarization of the insulating material is collected. Q 0. The amount of charge that begins to decay after polarization is complete. Q ini and the amount of termination charge at termination Q end The depolarization charge decay curve of the insulating material was obtained. We construct an optimized theoretical model of the space charge-limited current at the point where polarization characteristics are removed, analyze the depolarization charge decay curve of the insulating material, and calculate the intrinsic carrier mobility of the insulating material under different polarization electric fields. μ(t ); Based on the intrinsic carrier mobility of insulating materials under different polarized electric fields μ(t The Poole-Frenkel law was used to correct for the influence of the electric field, and the trap energy level distribution was obtained. .

[0026] Specifically, this embodiment uses a DCIC-Q(t) test system comprising three parts: a PC, a DCIC-Q(t) test system, and a DCIC-Q(t) test system. Q(t) Equipment and three-electrode system. The PC connects to a communication unit to control the voltage output of the high-voltage source, and also connects to a DCIC via optical fiber. Q (t) Device, acquiring charge information of insulating material placed in a three-electrode system; DCIC- Q (t) The equipment is connected to a high-voltage source, which is connected to a communication device. The voltage output is controlled via a PC, supplying voltage to the insulating material and transmitting test data back to the PC via optical fiber. In DCIC- Q (t) A no-voltage test was performed with the equipment disconnected. Following this, the integrating capacitance was calibrated, and the collected data showed a straight line with a slope, representing the value of the integrating capacitance. When testing the insulating material, it was placed in a three-electrode system for polarization, and then the voltage was removed. Based on this, the polarization charge accumulation curve and depolarization charge decay curve of the insulating material were obtained. After the test, the DCIC- Q (t) Discharge treatment is performed on the equipment, insulation materials and three-electrode system to eliminate residual charge.

[0027] DCIC- Q (t) Equipment integrating capacitor C int A 1MΩ resistor is connected in series with the three-electrode testing system to limit the current and protect the equipment. Current flows from the high-voltage source into the integrating capacitor, then through the insulating material under test. Therefore, the integral of the current flowing through the integrating capacitor with respect to time equals the integral of the current in the insulating material with respect to time. C int It can reflect the charge information of insulating materials.

[0028] The purpose of performing a non-pressure test on the insulation material is to eliminate... Q (t) The impact of internal equipment malfunctions or other factors on the measurement. The test duration is 30~90s, and the sampling step size is 1~2s. Under no pressure conditions, considering the existence of errors, the sampled charge value is below 1 nC and basically does not change with time. When voltage is applied across the integrating capacitor, the charge increases rapidly and linearly. After 20s, the integrated capacitance value is obtained through data calculation. The value is compared with the theoretical capacitance value to check whether the capacitor is intact and to ensure that the test equipment is ready.

[0029] In this embodiment, the insulation material thickness is 10~2000 μm. Before testing, the insulation material should be dried in a vacuum oven to remove moisture and other impurities. Before polarization, it should be cleaned with a sterile cotton cloth soaked in alcohol. Then, the insulation material is placed in a three-electrode system, and a voltage is output to the insulation material to polarize it. The polarization voltage is set to 1~20 kV, and the polarization time is 180~600 s. (DCIC-) Q(t) The sampling step size of the device is 1~2s to obtain the amount of charge generated at the moment of polarization. Q 0 and the amount of charge that begins to decay after polarization is complete. Q ini After polarization was completed, the voltage was removed. The depolarization time was 600–3000 s, and the sampling step size was 1–2 s. The depolarization charge decay curve of the insulating material and the termination charge at the end of the test were obtained. Q end .

[0030] After each test, press and hold DCIC- Q (t) Press the charge clearing button on the device for at least 5 seconds. Then, use a grounded discharge rod to directly contact the three-electrode system to create a short circuit, thereby removing any residual charge on the electrodes. Finally, apply a reverse low voltage of 10-50V to the insulating material for 30 seconds to counteract any residual charge that may remain within the insulating material.

[0031] The depolarization charge decay curves of insulating materials are analyzed to determine the release mechanism of trapped charges, obtaining the decay rate and stage divisions. Shallow traps release charges easily, corresponding to rapid decay in the early stage of the curve; deep traps release charges more slowly, corresponding to slow decay in the later stage of the curve. An optimized space charge limited current (SCLC) model is constructed to remove polarization characteristics. Combined with the obtained trapped charge release mechanism analysis, the intrinsic carrier mobility of the insulating material under different polarization electric fields is calculated. μ(t The theoretical model expression for SCLC is:

[0032] In the formula, J is the current density; e 0 is the vacuum permittivity, 8.854. 10-12; e r θ is the relative permittivity, with a value of 2.3; μ is the carrier mobility; E and d are the electric field and thickness of the insulating material, respectively; θ is the trap control parameter.

[0033] Because the current density fluctuates greatly due to external influences, the test results are unstable, and the calculated carrier mobility is not accurate enough. By optimizing the process by removing polarization characteristics, the relationship between carriers and charge was obtained, i.e., the expression for carrier mobility is as follows:

[0034] In the formula, q ( t ) represents charge density, and represents charge quantity. Q ( t The ratio of the volume of the sample to the volume of the test sample. e 0 is the vacuum permittivity. e 0 is the relative permittivity.

[0035] Furthermore, by correcting for the influence of the electric field using the Poole–Frenkel law, the trap energy level distribution is... The calculation expression is:

[0036] Where k is the Boltzmann constant, 1.38 10-23; T is the thermodynamic temperature; v is the escape frequency, 10¹²~10¹⁴ Hz; R is the average distance of the localized state, 5 10⁻⁹ m; e is the electron charge, 1.6 10-19C.

[0037] Through the trap energy level distribution The relationship between trap energy levels and carrier mobility was obtained. Since carrier mobility is related to depolarization time, the calculated trap energy level distribution was thus obtained. For a given range, the instantaneous charging charge generated at the moment of polarization of the insulating material is considered. Q 0. The amount of charge that begins to decay after polarization is complete. Q ini and the amount of termination charge at termination Q end The charge is determined to be either dissipated or has not yet escaped. The final charge at termination. Q end The amount of charge that begins to decay after polarization is complete Q ini There is a difference The difference can characterize the amount of charge dissipated, that is, represent the trap energy level distribution. The amount of charge stored within the energy level range, and the termination charge at termination. Q end The amount of charge that begins to decay after polarization is complete Q ini The difference between The expression is: .

[0038] Termination charge at termination Q end Instantaneous charging charge generated at the moment of polarization with insulating material Q There is a difference between 0 and 0. The difference can characterize the amount of charge that has not yet escaped, and the amount of charge that has not yet escaped represents the energy level distribution above the trap. The deeper trap energy level, the termination charge at termination.Q end Instantaneous charging charge generated at the moment of polarization with insulating material Q The expression for the difference between 0 and 0 is: .

[0039] Example 2 Based on the proposed embodiment, this invention provides a method for characterizing the trap properties of insulating materials. This embodiment focuses on insulating sample A and insulating sample B, and the working principle and technical solution of the invention will be further described in detail with reference to the accompanying drawings.

[0040] In DCIC- Q In the (t) technique, a series-connected integrating capacitor is used to obtain charge information of two insulating samples during polarization and depolarization, including the instantaneous charging charge generated at the moment of polarization. Q 0. The amount of charge that begins to decay after polarization is complete. Q ini The charge decay curve of the depolarization process and the termination charge at the end. Q end A theoretical model of space charge confinement current (SCLC) optimized for polarization characteristics was established, and the time-domain carrier mobility was obtained. m ( t The Poole-Frenkel law was introduced to correct for the influence of the electric field, and the trap energy level distribution of the insulating sample was calculated. .

[0041] Step 1: DCIC- Q (t) The test system connects the insulation sample as follows: Figure 1 As shown. Controlled by the PC, the high-voltage DC source supplies... Q (t) The equipment input voltage and current flow to the insulating sample via the integrating capacitor. During the test, the charge information of the insulating sample is transmitted via the DCIC- Q (t) The device acquires and transmits the signal to the PC receiver via optical fiber, and saves it in the form of an xlsx text file.

[0042] Step 2: In DCIC- Q (t) Perform a no-voltage test with the equipment disconnected. Then, calibrate the integrating capacitor. The collected data shows a straight line with a slope, representing the value of the integrating capacitor.

[0043] Step 3: This patent selects two different insulating samples, named Insulating Sample A and Insulating Sample B, with a thickness of 500 μm. The insulating samples are sequentially placed in a three-electrode system for polarization, with a polarization voltage of 15 kV, equivalent to an electric field of 30 kV / mm. The polarization time is set to 300 s, and the sampling step size is 2 s. After polarization, the voltage is removed, with a depolarization time of 900 s and a sampling step size of 2 s. The instantaneous charging charge generated at the moment of polarization is obtained. Q 0. The charge decay curve of the depolarization process and the termination charge at the end. Q end ,like Figure 2 As shown. Figure 3 This diagram illustrates the decomposition of charge, defining the physical meaning of different characteristic charges and the logic for calculating their differences. Figure 3 The decomposition model shown is obtained from the decay curve in Figure 2. The amount of charge stored within the energy level range and higher The amount of charge stored in the deep traps of the energy level :

[0044] The calculated amount of charge stored in different energy level ranges is plotted on Figure 4 After the test is completed, the DCIC- Q (t) Discharge treatment is performed on the equipment, insulation materials and three-electrode system to eliminate residual charge.

[0045] Step 4: Analyzing the depolarization charge decay curves of the insulating materials, and using an optimized SCLC model with polarization characteristics removed, the intrinsic carrier mobility of the two materials under different polarization electric fields was calculated. μ(t ):

[0046] in, e 0 is the vacuum permittivity, 8.854. 10 -12 ; e r is the relative permittivity, with a value of 2.3; q ( t ) represents charge density, and represents charge quantity. Q ( t The ratio of the volume of the sample to the volume of the test sample.

[0047] The trap energy level distribution was obtained by correcting for the influence of the electric field using Poole–Frenkel's law. Since carrier mobility varies with depolarization time, the trap energy level is also related to the depolarization time, i.e., it is within a certain range. Based on this, the trap energy level distribution of the insulating material was obtained. :

[0048] in, k is the Boltzmann constant, 1.38. 10 -23 ; T Thermodynamic temperature; v For escape frequency, 10 12 ~10 14 Hz; R The average distance of the local states, 5 10 -9 m; e For electron charge, 1.6 10 -19 C.

[0049] The trap energy level ranges for insulating materials A and B were obtained, such as... Figure 5 As shown in the figure, the trap energy level range of insulating material A is 0.71~0.84 eV, with a median of 0.80 eV; the trap energy level range of insulating material B is 0.71~0.86 eV, with a median of 0.81 eV.

[0050] According to the testing and characterization methods of this patent, the trap energy level range of insulating material A is 0.71~0.84 eV, with a median of 0.80 eV, and the stored charge is 1974.2 nC; the deep traps above 0.84 eV store 398.3 nC of charge. The trap energy level range of insulating material B is 0.71~0.86 eV, with a median of 0.81 eV, and the stored charge is 2211.1 nC; the deep traps above 0.86 eV store 767.2 nC of charge.

[0051] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can be appropriately combined to form other embodiments that can be understood by those skilled in the art. The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A method for characterizing the trapping properties of insulating materials, characterized in that, Includes the following steps: The insulating material is polarized, and then depolarized after a period of polarization. The instantaneous charging charge generated during the polarization of the insulating material is collected. Q 0. The amount of charge that begins to decay after polarization is complete. Q ini and the amount of termination charge at termination Q end The depolarization charge decay curve of the insulating material was obtained. Using a pre-constructed, optimized space charge-limited current theoretical model for removing polarization characteristics, the depolarization charge decay curve of the insulating material is analyzed, and the intrinsic carrier mobility of the insulating material under different polarization electric fields is calculated. μ(t ); Based on the intrinsic carrier mobility of insulating materials under different polarized electric fields μ(t The Poole-Frenkel law was used to correct for the influence of the electric field, and the trap energy level distribution was obtained. .

2. The method for characterizing the trap properties of insulating materials according to claim 1, characterized in that, The polarization period of the insulating material is specifically: through current integration of charge technology, in DCIC- Q (t) Under the test system conditions of 1~20kV, a voltage is output to the insulating material to polarize it. The polarization voltage is set to 1~20 kV, and the polarization time is 180~600 s. DCIC- Q (t) The sampling step size of the device is 1~2s.

3. The method for characterizing the trap properties of insulating materials according to claim 1, characterized in that, The depolarization time is 600~3000 s, DCIC- Q (t) The sampling step size of the device is 1~2 s.

4. The method for characterizing the trap properties of insulating materials according to claim 1, characterized in that, The expression for the space charge confinement current theoretical model optimized by polarization characteristics is as follows: In the formula, J Current density; ε 0 is the vacuum permittivity. ε r The relative permittivity, μ Carrier mobility; E and d These represent the electric field and thickness of the insulating material, respectively. θ These are the trap control parameters.

5. The method for characterizing the trap properties of insulating materials according to claim 1, characterized in that, The calculation of the intrinsic carrier mobility of the insulating material under different polarized electric fields. μ(t The intrinsic carrier mobility of insulating materials under different polarized electric fields. μ(t The calculation formula is as follows: In the formula, q ( t ) represents charge density, and represents charge quantity. Q ( t The ratio of the volume of the sample to the volume of the test sample. ε 0 is the vacuum permittivity. ε 0 is the relative permittivity.

6. The method for characterizing the trap properties of insulating materials according to claim 1, characterized in that, The intrinsic carrier mobility of insulating materials under different polarized electric fields is used as a basis. μ(t The Poole-Frenkel law was used to correct for the influence of the electric field, and the trap energy level distribution was obtained. Specifically, this involves correcting the effect of the electric field using the Poole–Frenkel law to adjust the trap energy level distribution. The calculation expression is: in, k Boltzmann's constant, T Thermodynamic temperature; v For escape frequency, R The average distance of the local states. e The amount of electron charge. E For the electric field of the insulating material, ε 0 is the vacuum permittivity. ε 0 is the relative permittivity.

7. The method for characterizing the trap properties of insulating materials according to claim 6, characterized in that, Through the trap energy level distribution The relationship between trap energy levels and carrier mobility was obtained. Since carrier mobility is related to depolarization time, the calculated trap energy level distribution was thus obtained. For a given range, the instantaneous charging charge generated at the moment of polarization of the insulating material is considered. Q 0. The amount of charge that begins to decay after polarization is complete. Q ini and the amount of termination charge at termination Q end The charge is determined to be either a dissipated charge or a charge that has not yet escaped.

8. The method for characterizing the trap properties of insulating materials according to claim 6, characterized in that, Termination charge at termination Q end The amount of charge that begins to decay after polarization is complete Q ini There is a difference The difference can characterize the amount of charge dissipated, that is, represent the trap energy level distribution. The amount of charge stored within the energy level range, and the termination charge at termination. Q end The amount of charge that begins to decay after polarization is complete Q ini The difference between The expression is: 。 9. The method for characterizing the trap properties of insulating materials according to claim 6, characterized in that, Termination charge at termination Q end Instantaneous charging charge generated at the moment of polarization with insulating material Q There is a difference between 0 and 0. The difference can characterize the amount of charge that has not yet escaped, and the amount of charge that has not yet escaped represents the energy level distribution above the trap. The deeper trap energy level, the termination charge at termination. Q end Instantaneous charging charge generated at the moment of polarization with insulating material Q The expression for the difference between 0 and 0 is: .

10. The method for characterizing the trapping properties of insulating materials according to claim 2, characterized in that, The DCIC-Q(t) test system includes a PC and a DCIC- Q (t) The equipment and three-electrode system, on the PC side, are connected to a communication device to control the voltage output of the high-voltage source, and on the other hand, they are connected to a DCIC via optical fiber. Q (t) Device, acquiring charge information of insulating material placed in a three-electrode system; DCIC- Q (t) The equipment is connected to a high-voltage source, outputs voltage to the insulating material, and transmits the test data back to the PC via optical fiber. The insulating material is placed in a three-electrode system for polarization, then the voltage is removed for depolarization. The depolarization charge decay curve of the insulating material is obtained. After the test is completed, the DCIC- Q (t) Discharge treatment is performed on the equipment, insulation materials and three-electrode system to eliminate residual charge.

Images