Epoxy resin-gridding cloth composite material optimization method and structure for high-frequency transformer

Abstract

The invention discloses an epoxy resin-gridding cloth composite material optimization method and structure for a high-frequency transformer, and the method comprises the steps: preparing a plurality of groups of epoxy resin-gridding cloth composite material samples for the high-frequency transformer, and constructing a three-dimensional finite element model only containing epoxy resin solid sealing insulation based on a high-frequency transformer geometric structure; the simulation model comprises an iron core, a low-voltage winding, a high-voltage winding and an epoxy resin solid-sealed insulator. Inputting material parameters, and simulating to obtain distribution of an electric field, a temperature field and a mechanical stress field under a reference working condition; assigning each group of physical parameters to the local buffer layer model for multi-physics field coupling simulation to obtain temperature, stress and electric field distribution under different grid cloth layer number configurations, and selecting the grid cloth layer number of which the temperature rise is reduced, the maximum stress is reduced and a high-field-intensity region is located in a high-breakdown-strength material according to a simulation result to obtain the multi-physical-field coupling simulation of the local buffer layer model. The high-frequency transformer solid-sealed insulation structure is used.

Description

Technical Field

[0001] This invention relates to the field of high-frequency transformer technology, and in particular to an optimization method and structure for epoxy resin-mesh fabric composite materials used in high-frequency transformers. Background Technology

[0002] Power electronic transformers enable distributed energy grid connection and flexible interconnection of AC / DC power grids, making them key equipment for constructing new power systems. High-frequency transformers, as the core components of power electronic transformers, are crucial for achieving electrical isolation and power transmission. Epoxy resin-encapsulated high-frequency transformers, with their advantages of small size, high power density, and excellent insulation performance, are widely used in energy conversion. However, high-frequency transformers operate under electric fields with short rise times, large amplitudes, and high frequencies for extended periods, subjecting the epoxy resin insulation to high-frequency electrical stress. Furthermore, the compact structure and poor heat dissipation of high-frequency transformers easily lead to uneven internal temperature distribution and localized stress concentration. The long-term combined electro-thermal effects on the epoxy resin-encapsulated insulation accelerate insulation aging, causing insulation cracking and seriously threatening the safe operation of high-frequency transformers. Therefore, research on epoxy resin-encapsulated insulation systems and the optimized design of high-frequency transformer insulation structures is of significant guiding importance for high-frequency transformer design.

[0003] Currently, research on optimizing the temperature, mechanical, and insulation properties of epoxy-sealed high-frequency transformers, both domestically and internationally, mainly focuses on modifying epoxy resin insulation materials to increase their thermal conductivity and insulation performance, thereby reducing the electric, temperature, and mechanical fields borne by the insulation. While this method, by developing materials with better performance, reduces the physical fields borne by the insulation to some extent, it cannot effectively solve the problem of localized physical field concentration caused by the structural design of the high-frequency transformer itself through modification of a single insulation material.

[0004] The information disclosed in the background section is only for enhancing the understanding of the background of this invention, and therefore may contain information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0005] This invention provides an optimization method and structure for epoxy resin-mesh fabric composite materials used in high-frequency transformers. Actual physical experiments involve preparing epoxy resin-mesh fabric composite materials with different numbers of mesh fabric layers and measuring the physical parameters of each type of composite material. Simulation calculations, by inputting the basic physical parameters obtained from the physical experiments, simulate the physical field distribution of the high-frequency transformer under the solidification of each composite material. This provides a basis for the effectiveness of the optimization design method using epoxy resin-mesh fabric composite materials for the insulation solidification structure of high-frequency transformers.

[0006] An optimization method for epoxy resin-mesh composite materials for high-frequency transformers includes:

[0007] Multiple sets of epoxy resin-mesh fabric composite material samples for high-frequency transformers were prepared, with different numbers of mesh fabric layers embedded in the samples. The physical parameters of each set of samples were measured, including relative permittivity, breakdown field strength, thermal conductivity, constant pressure heat capacity, tensile strength, Young's modulus, Poisson's ratio, and coefficient of thermal expansion. The correspondence between each set of physical parameters and the number of mesh fabric layers was established.

[0008] Based on the geometry of a high-frequency transformer, a three-dimensional finite element model containing only epoxy resin-insulated components was constructed. The simulation model includes the core, low-voltage winding, high-voltage winding, and epoxy resin-insulated components.

[0009] Input material parameters and simulate to obtain the electric field, temperature field and mechanical stress field distribution under the baseline working condition;

[0010] Each group of physical parameters was assigned to the local buffer layer model for multiphysics coupling simulation to obtain the temperature, stress and electric field distribution under different mesh layer configurations. Based on the simulation results, the mesh layer number in which the temperature rise decreases, the maximum stress decreases and the high field strength region is located in a high breakdown strength material was selected as the solid insulation structure of the high frequency transformer.

[0011] In the aforementioned optimization method for epoxy resin-mesh fabric composite material for high-frequency transformers, the mesh fabric is a glass fiber woven fabric with a single-layer thickness of 0.45 mm, and its embedding direction is parallel to the principal stress direction of the insulation layer.

[0012] In the aforementioned optimization method for epoxy resin-mesh cloth composite material for high-frequency transformers, a three-dimensional finite element model is established using COMSOL Multiphysics. The electric field simulation is based on high-frequency voltage excitation, the thermal field simulation is based on the winding Joule heat source, and the stress field is driven by thermal expansion and assembly preload.

[0013] In the aforementioned optimization method for epoxy resin-mesh composite materials for high-frequency transformers, the epoxy resin-mesh composite material samples include: circular epoxy resin-mesh samples with a thickness of 2 mm and a radius of 40 mm; circular epoxy resin-mesh samples with a thickness of 5 mm and a radius of 40 mm; and dumbbell-shaped epoxy resin-mesh samples with a thickness of 4 mm, a gauge length of 50 mm, and a middle parallel section width of 10 mm. 。

[0014] In the aforementioned optimization method for epoxy resin-mesh fabric composite materials for high-frequency transformers, the thickness of the local buffer layer model is 2 mm.

[0015] In the aforementioned optimization method for epoxy resin-mesh cloth composite material for high-frequency transformers, COMSOL Multiphysics finite element simulation software is used to add a solid-insulation model. The measurement parameters of epoxy resin material without mesh cloth are input into the material parameters of the solid-insulation model to simulate the physical field distribution of the high-frequency transformer under epoxy resin solidification without mesh cloth.

[0016] A 3D simulation model of a high-frequency transformer with solid insulation was established. A solid insulation buffer model with a thickness of 2mm was added between the low-voltage winding and the core, between the low-voltage winding and the high-voltage winding, and outside the high-voltage winding. Solid insulation models were added separately for the remaining parts.

[0017] Using COMSOL Multiphysics finite element simulation software, the measurement parameters of epoxy resin material with one layer of mesh cloth added were input into the material parameters of the 2mm thick solidified insulation buffer model. The other solidified insulation model material parameters were obtained by measuring epoxy resin without adding mesh cloth. The physical field distribution of the high-frequency transformer under epoxy resin solidification with one layer of mesh cloth added was simulated.

[0018] Using COMSOL Multiphysics finite element simulation software, the measurement parameters of epoxy resin material with two layers of mesh cloth were input into the material parameters of the 2mm thick solidified insulation buffer model. The other solidified insulation model material parameters were obtained by measuring epoxy resin without adding mesh cloth. The physical field distribution of the high-frequency transformer under epoxy resin solidification with two layers of mesh cloth was simulated.

[0019] Using COMSOL Multiphysics finite element simulation software, the measurement parameters of epoxy resin material with 3 layers of mesh cloth were input into the material parameters of the 2mm thick solidified insulation buffer model. The other solidified insulation model material parameters were obtained by measuring epoxy resin without adding mesh cloth. The physical field distribution of the high-frequency transformer under epoxy resin solidification with 3 layers of mesh cloth was simulated.

[0020] In the aforementioned optimization method for epoxy resin-mesh fabric composite materials for high-frequency transformers, a temperature-stress unidirectional coupling is adopted, and the temperature rise simulation results are input into the stress simulation calculation model to obtain the temperature field and stress field distribution of the high-frequency transformer.

[0021] In the aforementioned optimization method for epoxy resin-mesh fabric composite materials for high-frequency transformers, the region containing mesh fabric has a high dielectric constant but a low breakdown field strength, while the pure epoxy resin region has a low dielectric constant but a high insulation strength. By locally embedding a high dielectric constant buffer layer, the electric field lines are concentrated in the pure epoxy resin region.

[0022] An insulation structure for a high-frequency transformer is formed by an optimized method for an epoxy resin-mesh composite material for a high-frequency transformer.

[0023] In the aforementioned high-frequency transformer insulation structure, a buffer layer is arranged between the low-voltage winding and the iron core, between the low-voltage and high-voltage windings, and on the outside of the high-voltage winding. The buffer layer has a thickness of 2mm and contains 1 to 3 layers of glass fiber mesh. The temperature rise is ≤80℃, the maximum mechanical stress is ≤58MPa, and the high electric field region is located in a high breakdown strength material.

[0024] Compared with the prior art, the present invention has the following advantages: The present invention can optimize the solidification insulation structure of the high-frequency transformer by using epoxy resin-mesh cloth composite material without changing the original structure of the high-frequency transformer, so as to reduce the temperature field and mechanical field of the insulation, optimize the electric field distribution of the insulation, and improve the problem of local physical field concentration. Attached Figure Description

[0025] Various other advantages and benefits of the present invention will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiments below. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. It is obvious that the drawings described below are merely some embodiments of the invention, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort. Furthermore, the same reference numerals denote the same parts throughout the drawings.

[0026] In the attached diagram:

[0027] Figure 1 This is a flowchart of a research method for optimizing the temperature, mechanical, and insulation properties of an epoxy resin-mesh composite material for high-frequency transformers, as described in this invention.

[0028] Figure 2 This is a flowchart of the simulation of the temperature rise field and stress field of the epoxy resin-mesh cloth composite material for high-frequency transformers in this invention;

[0029] Figure 3 This is a photograph of the sample prepared in this invention;

[0030] Figure 4 This is a 3D simulation model diagram of a high-frequency transformer without solid insulation established in this invention;

[0031] Figure 5 This is a physical field distribution diagram of the epoxy resin-encapsulated high-frequency transformer without mesh cloth used in this invention;

[0032] Figure 6 This is a 3D simulation model diagram of a high-frequency transformer with a solid-insulated buffer layer established in this invention;

[0033] Figure 7 This is a physical field distribution diagram of the epoxy resin-encapsulated high-frequency transformer containing one layer of mesh cloth used in this invention;

[0034] Figure 8 This is a physical field distribution diagram of the epoxy resin-encapsulated high-frequency transformer containing two layers of mesh cloth used in this invention.

[0035] Figure 9 This is a physical field distribution diagram of the epoxy resin-encapsulated high-frequency transformer containing three layers of mesh cloth used in this invention.

[0036] The present invention will be further explained below with reference to the accompanying drawings and embodiments. Detailed Implementation

[0037] Specific embodiments of the invention will now be described in more detail with reference to the accompanying drawings. While specific embodiments of the invention are shown in the drawings, it should be understood that the invention may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this invention will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0038] It should be noted that certain terms are used in the specification and claims to refer to specific components. Those skilled in the art will understand that different terms may be used to refer to the same component. This specification and claims do not distinguish components based on differences in terminology, but rather on differences in function. The terms "comprising" or "including" used throughout the specification and claims are open-ended and should be interpreted as "comprising but not limited to." The following descriptions are preferred embodiments for carrying out the invention; however, these descriptions are for the purpose of understanding the general principles of the specification and are not intended to limit the scope of the invention. The scope of protection of this invention is determined by the appended claims.

[0039] To facilitate understanding of the embodiments of the present invention, further explanations and descriptions will be provided below with reference to the accompanying drawings and specific embodiments. The accompanying drawings do not constitute a limitation on the embodiments of the present invention.

[0040] like Figures 1 to 9 As shown, the optimization method for epoxy resin-mesh fabric composite materials for high-frequency transformers includes the following steps:

[0041] Multiple sets of epoxy resin-mesh fabric composite material samples for high-frequency transformers were prepared, with different numbers of mesh fabric layers embedded in the samples. The physical parameters of each set of samples were measured, including relative permittivity, breakdown field strength, thermal conductivity, constant pressure heat capacity, tensile strength, Young's modulus, Poisson's ratio, and coefficient of thermal expansion. The correspondence between each set of physical parameters and the number of mesh fabric layers was established.

[0042] Based on the geometry of a high-frequency transformer, a three-dimensional finite element model containing only epoxy resin-sealed insulation was constructed. The simulation model includes the core, low-voltage winding, high-voltage winding, and epoxy resin-sealed insulation. By inputting material parameters, the electric field, temperature field, and mechanical stress field distribution under the reference operating conditions were obtained through simulation. Taking a high-frequency transformer with a rated power of 200kVA and an operating frequency of 10kHz as the research object, the simulation results show that the maximum electric field of the high-frequency transformer is 0.372kV / mm, the maximum temperature rise is 103℃, and the maximum mechanical stress is 74.2MPa.

[0043] Based on the geometry of a high-frequency transformer, a three-dimensional finite element model of epoxy resin-mesh cloth buffer insulation was constructed. The locally added buffer insulation models are located between the low-voltage winding and the core, between the low-voltage winding and the high-voltage winding, and outside the high-voltage winding. The simulation model includes the core, low-voltage winding, high-voltage winding, epoxy insulation, and epoxy resin-mesh cloth insulation. Each set of physical parameters was assigned to the local buffer layer model for multiphysics coupling simulation to obtain the temperature, stress, and electric field distributions under different mesh cloth layer configurations. Based on the simulation results, the mesh cloth layer number selected where temperature rise decreases, maximum stress decreases, and the high electric field region is located in a high breakdown strength material was chosen as the high-frequency transformer insulation structure.

[0044] The specific implementation is as follows: Taking a high-frequency transformer with a rated power of 200kVA and an operating frequency of 10kHz as the research object, the low-voltage winding and the core, the high-voltage winding and the low-voltage winding, and the outer side of the high-voltage winding adopt an epoxy resin-mesh cloth composite sealing and insulation structure, while the remaining parts are insulated and sealed with epoxy resin. The epoxy resin matrix is ​​bisphenol A type epoxy resin, the curing agent is an acid anhydride curing agent, and the mesh cloth is glass fiber mesh cloth.

[0045] Multiple composite material samples containing 1, 2, and 3 layers of mesh fabric were prepared, with each single layer of mesh fabric having a thickness of 0.45 mm and adjacent mesh fabrics being completely impregnated and filled with epoxy resin.

[0046] The relative permittivity, breakdown field strength, thermal conductivity, constant pressure heat capacity, tensile strength, Young's modulus, Poisson's ratio and coefficient of thermal expansion of each group of samples were measured. The measurement results were used as material parameters and input into the three-dimensional finite element model.

[0047] Based on the actual geometry of the high-frequency transformer, a three-dimensional finite element model of the insulation with an epoxy resin-mesh cloth buffer layer was established. The added buffer layer insulation model is located between the low-voltage winding and the core, between the low-voltage winding and the high-voltage winding, and outside the high-voltage winding. A voltage excitation condition of 8kV and 10kHz was applied, and winding losses, core losses, and dielectric losses were considered as heat sources. Multiphysics field coupling simulation of electric field, temperature field, and mechanical stress field was performed.

[0048] Simulation results show that as the number of mesh layers increases from 1 to 3, the maximum electric field strength near the high-voltage winding remains almost unchanged, and the high electric field region is mainly distributed inside the epoxy resin-encapsulated insulation with higher breakdown field strength, forming an "electric field guiding" effect. The peak temperature rise gradually decreases from 85℃ to 79.8℃; the local mechanical stress gradually decreases from 62.9MPa to 57.2MPa. Compared with the simulation results of the high-frequency transformer without the epoxy resin-mesh buffer layer encapsulated insulation, the high-frequency transformer with 3 layers of mesh insulation achieves optimized electric field distribution, reducing the maximum temperature rise by 22.5% and the maximum mechanical stress by 22.9%, further demonstrating the effectiveness of this insulation optimization design method with a mesh buffer layer.

[0049] Therefore, adding three layers of mesh fabric is selected as the optimal configuration for the solidification insulation structure of high-frequency transformers.

[0050] In a preferred embodiment of the optimization method for epoxy resin-mesh fabric composite material for high-frequency transformers, the mesh fabric is a glass fiber woven fabric with a single layer thickness of 0.45 mm and an embedding direction parallel to the principal stress direction of the insulation layer.

[0051] In a preferred embodiment of the optimization method for epoxy resin-mesh cloth composite material for high-frequency transformers, a three-dimensional finite element model is established using COMSOL Multiphysics. The electric field simulation is based on high-frequency voltage excitation, the thermal field simulation is based on the winding Joule heat source, and the stress field is driven by thermal expansion and assembly preload.

[0052] In a preferred embodiment of the optimization method for epoxy resin-mesh composite material for high-frequency transformers, the epoxy resin-mesh composite material sample includes: a circular epoxy resin-mesh sample with a thickness of 2 mm and a radius of 40 mm, a circular epoxy resin-mesh sample with a thickness of 5 mm and a radius of 40 mm, and a dumbbell-shaped epoxy resin-mesh sample with a thickness of 4 mm, a gauge length of 50 mm, and a middle parallel section width of 10 mm. 。

[0053] In a preferred embodiment of the optimization method for epoxy resin-mesh fabric composite material for high-frequency transformers, the thickness of the local buffer layer model is 2 mm.

[0054] In a preferred embodiment of the optimization method for epoxy resin-mesh cloth composite material for high-frequency transformers, COMSOL Multiphysics finite element simulation software is used to add a solid-insulation model. The measurement parameters of epoxy resin material without mesh cloth are input into the material parameters of the solid-insulation model to simulate the physical field distribution of the high-frequency transformer under epoxy resin solidification without mesh cloth.

[0055] A 3D simulation model of a high-frequency transformer with solid insulation was established. A solid insulation buffer model with a thickness of 2mm was added between the low-voltage winding and the core, between the low-voltage winding and the high-voltage winding, and outside the high-voltage winding. Solid insulation models were added separately for the remaining parts.

[0056] Using COMSOL Multiphysics finite element simulation software, the measurement parameters of epoxy resin material with one layer of mesh cloth added were input into the material parameters of the 2mm thick solidified insulation buffer model. The other solidified insulation model material parameters were obtained by measuring epoxy resin without adding mesh cloth. The physical field distribution of the high-frequency transformer under epoxy resin solidification with one layer of mesh cloth added was simulated.

[0057] Using COMSOL Multiphysics finite element simulation software, the measurement parameters of epoxy resin material with two layers of mesh cloth were input into the material parameters of the 2mm thick solidified insulation buffer model. The other solidified insulation model material parameters were obtained by measuring epoxy resin without adding mesh cloth. The physical field distribution of the high-frequency transformer under epoxy resin solidification with two layers of mesh cloth was simulated.

[0058] Using COMSOL Multiphysics finite element simulation software, the measurement parameters of epoxy resin material with 3 layers of mesh cloth were input into the material parameters of the 2mm thick solidified insulation buffer model. The other solidified insulation model material parameters were obtained by measuring epoxy resin without adding mesh cloth. The physical field distribution of the high-frequency transformer under epoxy resin solidification with 3 layers of mesh cloth was simulated.

[0059] In a preferred embodiment of the optimization method for epoxy resin-mesh cloth composite material for high-frequency transformers, temperature-stress unidirectional coupling is adopted, and the temperature rise simulation results are input into the stress simulation calculation model to obtain the temperature field and stress field distribution of the high-frequency transformer.

[0060] In a preferred embodiment of the optimization method for epoxy resin-mesh fabric composite material for high-frequency transformers, the region containing mesh fabric has a high dielectric constant but a low breakdown field strength, while the pure epoxy resin region has a low dielectric constant but a high insulation strength; by locally embedding a high dielectric constant buffer layer, the electric field lines are concentrated in the pure epoxy resin region.

[0061] An insulation structure for a high-frequency transformer is formed by an optimized method for an epoxy resin-mesh composite material for a high-frequency transformer.

[0062] In a preferred embodiment of the high-frequency transformer insulation structure, a buffer layer is arranged between the low-voltage winding and the core, between the low-voltage and high-voltage windings, and on the outside of the high-voltage winding. The buffer layer has a thickness of 2mm and contains 1 to 3 layers of glass fiber mesh. The temperature rise is ≤80℃, the maximum mechanical stress is ≤58MPa, and the high electric field region is located in a high breakdown strength material.

[0063] In one embodiment, the method includes a physical experiment and a simulation experiment, wherein the actual physical experiment includes the following steps:

[0064] (1) ① Sample 1: Prepare a circular epoxy resin sample with a thickness of 2 mm and a radius of 40 mm. Add a mesh cloth of the same size and a thickness of 0.45 mm inside the sample. The number of layers added ranges from 0 to 3. ② Sample 2: Prepare a circular epoxy resin sample with a thickness of 5 mm and a radius of 40 mm. Add a mesh cloth of the same size and a thickness of 0.45 mm inside the sample. The number of layers added ranges from 0 to 3. ③ Sample 3: Prepare a dumbbell-shaped epoxy resin sample with a thickness of 4 mm, a gauge length of 50 mm, and a middle parallel section width of 10 mm. Add a mesh cloth of the same size and a thickness of 0.45 mm inside the sample. The number of layers added ranges from 0 to 3.

[0065] (2) For sample 1, the dielectric constant and breakdown field strength of epoxy resin-mesh composite material with different numbers of mesh layers were measured;

[0066] (3) For sample 2, the thermal conductivity and constant pressure heat capacity of epoxy resin-mesh composite material with different numbers of mesh layers were measured;

[0067] (4) For sample 3, the tensile strength, Young's modulus, Poisson's ratio and coefficient of thermal expansion of epoxy resin-mesh composite material with different numbers of mesh layers were measured;

[0068] The simulation calculation experiment described above includes the following steps:

[0069] (1) Based on the actual high-frequency transformer structure geometric parameters, establish a 3D simulation model of the high-frequency transformer without solid insulation;

[0070] (2) Using COMSOL Multiphysics finite element simulation software, add a solid-insulation model, input the measurement parameters of epoxy resin material without mesh cloth into the material parameters of the solid-insulation model, and simulate the physical field distribution of the high-frequency transformer under epoxy resin solid-insulation without mesh cloth.

[0071] (3) Establish a 3D simulation model of a high-frequency transformer with solid insulation. Add a 2mm thick solid insulation buffer model between the low-voltage winding and the core, between the low-voltage winding and the high-voltage winding, and outside the high-voltage winding of the high-frequency transformer. Add solid insulation models separately for the remaining parts.

[0072] (4) Using COMSOL Multiphysics finite element simulation software, input the measurement parameters of epoxy resin material with 1 layer of mesh cloth added into the material parameters of the 2mm thick solidified insulation buffer model in step (3). Use the parameters obtained by measuring epoxy resin without adding mesh cloth for the remaining solidified insulation model material parameters to simulate the physical field distribution of the high-frequency transformer under epoxy resin solidification with 1 layer of mesh cloth added.

[0073] (5) Using COMSOL Multiphysics finite element simulation software, input the measurement parameters of epoxy resin material with 2 layers of mesh cloth into the material parameters of the 2mm thick solidified insulation buffer model in step (3). Use the parameters obtained by measuring epoxy resin without adding mesh cloth for the remaining solidified insulation model material parameters to simulate the physical field distribution of the high-frequency transformer under epoxy resin solidification with 2 layers of mesh cloth.

[0074] (6) Using COMSOL Multiphysics finite element simulation software, input the measurement parameters of epoxy resin material with 3 layers of mesh cloth into the material parameters of the 2mm thick solidified insulation buffer model in step (3). Use the parameters obtained by measuring epoxy resin without adding mesh cloth for the remaining solidified insulation model material parameters to simulate the physical field distribution of the high-frequency transformer under epoxy resin solidification with 3 layers of mesh cloth.

[0075] In one embodiment, the method flow is as follows: Figure 1 As shown, the simulation of the temperature rise field and stress field of the epoxy resin-mesh composite material for high-frequency transformers adopts a temperature-stress unidirectional coupling simulation model, and the simulation process is as follows: Figure 2 As shown, the present invention specifically includes the following processes:

[0076] (1) Prepare three types of epoxy resin-mesh composite material samples required for the physical experiment. The specific dimensions of the samples are as described above. The prepared samples are as follows: Figure 3 As shown;

[0077] (2) The physical parameters required for simulation were measured on the prepared sample. The measurement results are shown in the table below.

[0078]

[0079] (3) Based on the actual high-frequency transformer structural geometric parameters, establish a 3D simulation model of the high-frequency transformer without solid insulation, such as... Figure 4 As shown, it includes an iron core, low-voltage winding, high-voltage winding, and outer casing;

[0080] (4) Using the finite element simulation software COMSOL Multiphysics, a solid-insulation model was added. The physical parameters of the epoxy resin material without mesh fabric obtained from the above measurements were input into the material parameters of the solid-insulation model. The physical field distribution of the high-frequency transformer under epoxy resin solidification without mesh fabric was simulated as follows: Figure 5 As shown. The results show that when using a single epoxy resin as the solidification insulation, the maximum temperature rise of the high-frequency transformer is 103℃, and the hot spot appears between the low-voltage winding and the core. The maximum stress is 74.2MPa, which appears between the two high-voltage windings. The maximum electric field is 0.372kV / mm, which appears near the high-voltage winding.

[0081] (5) Establish a 3D simulation model of a high-frequency transformer with a solid insulation buffer layer. Add a 2mm thick solid insulation buffer layer model between the low-voltage winding and the core, between the low-voltage winding and the high-voltage winding, and outside the high-voltage winding of the high-frequency transformer, such as... Figure 6 As shown, the remaining parts are added separately as solid-insulation models;

[0082] (6) Using the finite element simulation software COMSOL Multiphysics, import the simulation model of the high-frequency transformer with a solidified insulation buffer layer. Input the physical parameters of the epoxy resin material with one layer of mesh cloth added, as measured above, into the material parameters of the solidified insulation buffer layer model. The simulation parameters of the remaining solidified parts are the physical parameters measured with epoxy resin without mesh cloth. The simulation results show the physical field distribution of the high-frequency transformer under epoxy resin solidification with one layer of mesh cloth added, as follows: Figure 7 As shown. The results show that when using an epoxy resin buffer layer with one layer of mesh cloth and pure epoxy resin as solid insulation, the maximum temperature rise of the high-frequency transformer is 85℃, and the hot spot appears between the low-voltage winding and the core. The maximum stress is 62.9MPa, which appears between the two high-voltage windings. The maximum electric field is 0.381kV / mm. Since the relative permittivity of the epoxy resin with mesh cloth is greater than that of pure epoxy resin, the high electric field value is distributed in the pure epoxy resin solid insulation with low permittivity and high insulation strength.

[0083] (7) Using the finite element simulation software COMSOL Multiphysics, import the simulation model of the high-frequency transformer with the solidified insulation buffer layer. Input the physical parameters of the epoxy resin material with two layers of mesh cloth obtained above into the material parameters of the solidified insulation buffer layer model. The simulation parameters of the remaining solidified part are the physical parameters obtained by measuring the epoxy resin without adding mesh cloth. The simulation results show the physical field distribution of the high-frequency transformer under the epoxy resin solidification with two layers of mesh cloth as follows: Figure 8 As shown. The results show that when using epoxy resin buffer layer with two layers of mesh cloth and pure epoxy resin as solid insulation, the maximum temperature rise of the high-frequency transformer is 80.1℃, and the hot spots appear in the low-voltage winding and the core. The maximum stress is 57.6MPa, which appears between the two high-voltage windings. The maximum electric field is 0.381kV / mm. Since the relative permittivity of the epoxy resin containing the mesh cloth is greater than that of the pure epoxy resin, the high electric field value is distributed in the pure epoxy resin solid insulation with low permittivity and high insulation strength.

[0084] (8) Using the finite element simulation software COMSOL Multiphysics, import the simulation model of the high-frequency transformer with the solidified insulation buffer layer. Input the physical parameters of the epoxy resin material with 3 layers of mesh cloth obtained above into the material parameters of the solidified insulation buffer layer model. The simulation parameters of the remaining solidified parts are the physical parameters obtained by measuring the epoxy resin without adding mesh cloth. The simulation results show the physical field distribution of the high-frequency transformer under the epoxy resin solidification with 3 layers of mesh cloth as follows: Figure 9 As shown. The results show that when using an epoxy resin buffer layer with three layers of mesh cloth and pure epoxy resin as the solidification insulation, the maximum temperature rise of the high-frequency transformer is 79.8℃, and the hot spots appear in the low-voltage winding and the core. The maximum stress is 57.2MPa, which occurs between the two high-voltage windings. This effectively reduces the temperature and stress of the high-frequency transformer. The maximum electric field is 0.381kV / mm. Since the relative permittivity of the epoxy resin containing the mesh cloth is greater than that of the pure epoxy resin, the high electric field value is distributed in the pure epoxy resin solidification insulation with low permittivity and high insulation strength, which effectively optimizes the distribution of the electric field of the high-frequency transformer.

[0085] Furthermore, this invention addresses the problem of localized hot spots and thermal stress concentration caused by the compact structure and difficult heat dissipation of high-frequency transformers. By locally embedding an epoxy resin composite buffer layer containing fiberglass mesh in key areas (such as the gap between windings and the core, between windings, and on the outside of the high-voltage winding), this invention significantly improves the thermal conductivity of these areas (from 0.52 W / m·K to 0.71 W / m·K) and reduces the coefficient of thermal expansion (from 3.0 × 10⁻⁶ W / m·K). -5 K -1 Reduced to 2.1×10 -5 K -1This not only accelerates heat transfer to the outside, effectively reducing the maximum temperature rise from 103℃ to 79.8℃, but also significantly reduces the thermal expansion mismatch between the epoxy resin and the metal components (copper windings, silicon steel sheets), thereby suppressing the generation and development of interfacial microcracks. Simultaneously, the high modulus properties of the mesh fabric (Young's modulus increased from 4.8GPa to 5.16GPa) enhance the composite material's resistance to deformation, reducing the maximum mechanical stress from 74.2MPa to 57.2MPa, significantly improving the long-term reliability of the insulation structure under thermal cycling and vibration conditions.

[0086] Secondly, regarding electric field control, this invention cleverly utilizes the controllable gradient distribution of the dielectric constant of the composite material to optimize the electric field gradient distribution: as the number of mesh layers increases, the dielectric constant of the composite material increases from 3.78 to 4.65. Although this slightly reduces the breakdown field strength (19.6 → 17.1 kV / mm), by setting a high dielectric constant buffer layer only in the non-maximum electric field region, the high electric field region is retained as pure epoxy resin (low dielectric constant, high breakdown strength), forming an "electric field guiding" effect. Simulation results show that the maximum electric field value remains stable at around 0.381 kV / mm, and the high field strength region is effectively "pushed" to the pure epoxy resin region with better insulation performance, avoiding electrical breakdown in the mechanically reinforced region, and achieving decoupling optimization and synergistic matching of electro-thermal-mechanical properties.

[0087] Furthermore, this invention adopts a "local reinforcement, overall unchanged" design strategy, introducing composite materials only within the 2mm thin layer where stress and temperature rise are most severe, while the remaining insulation areas still use traditional epoxy resin. This avoids the increased complexity and cost of replacing the entire structure, and precisely targets the root cause of multiphysics coupling failure. Combined with an experimental-simulation closed-loop verification process—first, accurately calibrating the complete set of thermal, mechanical, and electrical parameters of the composite material under different mesh layer numbers through physical experiments, and then inputting them into a multiphysics finite element model for quantitative evaluation—this ensures the engineering feasibility and predictive accuracy of the optimized solution.

[0088] Although embodiments of the present invention have been described above in conjunction with the accompanying drawings, the present invention is not limited to the specific embodiments and application fields described above. The specific embodiments described above are merely illustrative and instructive, and not restrictive. Those skilled in the art can make many other forms based on the guidance of this specification and without departing from the scope of protection of the claims of the present invention, and all of these are within the scope of protection of the present invention.

Claims

1. An optimization method for epoxy resin-mesh fabric composite materials for high-frequency transformers, characterized in that, Includes the following steps: Multiple sets of epoxy resin-mesh fabric composite material samples for high-frequency transformers were prepared, with different numbers of mesh fabric layers embedded in the samples. The physical parameters of each set of samples were measured, including relative permittivity, breakdown field strength, thermal conductivity, constant pressure heat capacity, tensile strength, Young's modulus, Poisson's ratio, and coefficient of thermal expansion. The correspondence between each set of physical parameters and the number of mesh fabric layers was established. Based on the geometry of a high-frequency transformer, a three-dimensional finite element model containing only epoxy resin-insulated components was constructed. The simulation model includes the core, low-voltage winding, high-voltage winding, and epoxy resin-insulated components. Input material parameters and simulate to obtain the electric field, temperature field and mechanical stress field distribution under the benchmark working condition; assign each set of physical parameters to the local buffer layer model to perform multi-physics coupling simulation to obtain the temperature, stress and electric field distribution under different mesh layer configurations; based on the simulation results, select the mesh layer number in the high-breakdown strength material where the temperature rise decreases, the maximum stress decreases and the high field strength region is located as the solid-sealing insulation structure of the high-frequency transformer.

2. The optimization method for epoxy resin-mesh fabric composite material for high-frequency transformers according to claim 1, preferably, is characterized in that, The mesh fabric is made of woven glass fiber with a single layer thickness of 0.45 mm, and its embedding direction is parallel to the principal stress direction of the insulation layer.

3. The optimization method for epoxy resin-mesh fabric composite material for high-frequency transformers according to claim 1, characterized in that, Use COMSOL Multiphysics to build a three-dimensional finite element model.

4. The optimization method for epoxy resin-mesh fabric composite material for high-frequency transformers according to claim 3, characterized in that, The electric field simulation is based on high-frequency voltage excitation, the thermal field simulation is based on the winding Joule heat source, and the stress field is driven by thermal expansion and assembly preload.

5. The optimization method for epoxy resin-mesh fabric composite material for high-frequency transformers according to claim 1, characterized in that, The epoxy resin-mesh composite material samples include: circular epoxy resin-mesh samples with a thickness of 2 mm and a radius of 40 mm; circular epoxy resin-mesh samples with a thickness of 5 mm and a radius of 40 mm; and dumbbell-shaped epoxy resin-mesh samples with a thickness of 4 mm, a gauge length of 50 mm, and a middle parallel section width of 10 mm. 。 6. The optimization method for epoxy resin-mesh fabric composite material for high-frequency transformers according to claim 1, characterized in that, The thickness of the local buffer layer model is 2mm.

7. The optimization method for epoxy resin-mesh fabric composite material for high-frequency transformers according to claim 1, characterized in that, By employing temperature-stress unidirectional coupling, the temperature rise simulation results are input into the stress simulation calculation model to obtain the temperature field and stress field distribution of the high-frequency transformer.

8. The optimization method for epoxy resin-mesh fabric composite material for high-frequency transformers according to claim 1, characterized in that, The region containing the mesh fabric has a high dielectric constant but a low breakdown field strength, while the pure epoxy resin region has a low dielectric constant but a high insulation strength. By locally embedding a high dielectric constant buffer layer, the electric field lines are concentrated in the pure epoxy resin region.

9. A high-frequency transformer insulation structure, characterized in that, It is formed by an optimization method for an epoxy resin-mesh composite material for a high-frequency transformer according to any one of claims 1-8.

10. The high-frequency transformer insulation structure according to claim 9, characterized in that, The buffer layer is arranged between the low-voltage winding and the iron core, between the low-voltage and high-voltage windings, and on the outside of the high-voltage winding. It has a thickness of 2mm and contains 1 to 3 layers of glass fiber mesh. The temperature rise is ≤80℃, the maximum mechanical stress is ≤58MPa, and the high electric field region is located in a high breakdown strength material.

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