High-voltage coil structure of high-voltage and high-frequency transformer

Abstract

The invention provides a high-voltage coil structure of a high-voltage and high-frequency transformer, which belongs to the technical field of insulation of high-voltage and high-frequency transformers and comprises a main body structure and a hollowed-out wire outlet end which are integrally formed by vacuum casting of insulating materials. A stress cone structure and an umbrella skirt structure are sequentially arranged on the side wall surface of the hollow wire outlet end from back to front; the grounding shielding layer is tightly coated on the outer surface of the insulating material and is cut off at the stress cone structure; the front end of the hollowed-out wire outlet end is provided with a hollowed-out structure, so that the creepage distance and the electrical gap between the high-voltage terminal and the ground potential are further extended on the basis of the overall length of the hollowed-out wire outlet end, and the axial length of the hollowed-out wire outlet end is shortened at the same time. According to the invention, the overall weight of the hollowed-out wire outlet end is reduced while the creepage distance along the surface and the electrical clearance requirements are considered, so that the mechanical stability of a connection area is further enhanced, and the reliability of long-term operation of an insulation system is effectively guaranteed.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high-voltage high-frequency transformer insulation, and particularly relates to a high-voltage high-frequency transformer high-voltage coil structure. BACKGROUND

[0002] With the continuous improvement of AI model size and complexity, the global computing power demand is growing exponentially, and computing power has become a new productivity after heat and electricity. This trend is generating a wave of super-large data center infrastructure, while also bringing unprecedented challenges to the power supply architecture. The current mainstream low-voltage power supply scheme has reached the physical limit in terms of space occupation, copper consumption and energy efficiency, and it is difficult to meet the power supply needs of AI computing clusters with ultra-high power density. In this context, the high-voltage direct-hanging scheme based on solid-state transformers is considered as an important path to break through the current data center power supply bottleneck due to its high efficiency, high power density and high reliability advantages.

[0003] As the only component for realizing high-low voltage isolation in the solid-state transformer system, the low partial discharge and high reliability design of the high-voltage high-frequency transformer directly determines the operation life of the entire system. Among them, the transformer outlet terminal is the shortest creepage path between high and low potentials in the insulation system, and its design needs to consider both insulation breakdown and the requirement of surface creepage distance. Especially after the introduction of the outer shielding layer of the ground potential, on the one hand, the creepage distance from the high-voltage terminal to the ground potential and the flash distance are significantly shortened, and it is difficult to meet the minimum creepage distance and air gap requirements specified in the IEC standard; on the other hand, at the cutoff position of the grounding shielding layer at the outlet terminal, the air, conductor and insulating medium form a typical three-state interface, resulting in serious distortion of the surface electric field distribution and a sharp increase in local peak stress.

[0004] Currently, the insulation design of the high-frequency transformer outlet terminal mainly faces medium and low voltage level applications. Under such voltage conditions, the length of the outlet terminal required to meet the creepage distance and electrical clearance requirements only accounts for a small part of the overall length of the cast medium-voltage coil, as shown in FIG. 1. Figure 1 However, with the continuous growth of solid-state transformer capacity, high-voltage has become an inevitable trend in order to achieve higher energy efficiency and reduce copper consumption. Since solid-state transformers mostly use cascaded topologies, the increase in system capacity and voltage level can be achieved by increasing the number of cascaded modules, which means that the internal high-frequency transformer needs to withstand higher common-mode voltage while the power level remains basically unchanged. In this case, although the thickness of the main insulation increases to some extent, in order to meet the strict requirements of high-voltage insulation level on creepage distance and electrical clearance, the length of the outlet terminal in the high-voltage coil will significantly increase, as shown in FIG. 2. Figure 2As shown in the figure. At this time, the length of the outgoing line end even exceeds the length of the high-voltage line package main body structure, which on the one hand leads to a substantial decrease in the power density of the transformer, and on the other hand also challenges the mechanical stability of the connection between the main body structure and the outgoing line end, seriously restricting the long-term operation reliability of the insulation system. Therefore, it is urgent to propose a lightweight, high-power density, and high-reliability design scheme for the high-voltage line package of the high-voltage high-frequency transformer. SUMMARY

[0005] In view of the above technical defects existing in the prior art, the present application provides a high-voltage line package structure of a high-voltage high-frequency transformer. The high-voltage line package structure effectively realizes high-power density and high-reliability design of the high-voltage line package under the premise of ensuring that the electrical clearance and creepage distance requirements are met.

[0006] In one aspect, the present application provides a high-voltage line package structure of a high-voltage high-frequency transformer, comprising a main body structure and a hollow outgoing line end integrally vacuum cast by an insulating material; the main body structure is provided with a densely wound coil, the side wall surface of the hollow outgoing line end is provided with a stress cone structure and an umbrella skirt structure from back to front in turn, and a hollow structure for increasing the creepage distance and the electrical clearance is arranged on the front end surface of the hollow outgoing line end; the stress cone structure comprises a rising section, a horizontal section and a descending section, wherein the rising section comprises a circular arc-shaped concave structure; two lead wires are led out from the densely wound coil and pass through the inside of the hollow outgoing line end to the bottom surface of the hollow structure; the outer surface of the main body structure is coated with a grounding shielding layer, and the grounding shielding layer extends and covers part of the stress cone structure area.

[0007] Preferably, the insulating material is epoxy resin or silica gel, and the thickness of the insulating material between the densely wound coil and the grounding shielding layer is satisfies ; wherein, V DIL is the design insulation strength, k saf is the safety factor, E ref is the nominal breakdown field strength of the insulating material, d ref is the insulating material thickness corresponding to the nominal breakdown field strength, n is the attenuation coefficient of the breakdown field strength with the increase of the insulating material thickness.

[0008] The present application also provides a design method of the aforementioned high-voltage line package structure of a high-voltage high-frequency transformer, comprising the following steps: S1: determining the design insulation strength, the minimum creepage distance and the minimum electrical clearance of the high-voltage high-frequency transformer; S2: determining the thickness of the insulating material between the two lead wires according to the differential mode voltage between the two lead wire ends of the high-voltage winding V ​D isi ; determining the thickness of the insulation material between the tightly wound coil and the ground shielding layer according to the insulation strength of the high-voltage high-frequency transformer D iso ; S3: determining the value range of the stress cone structure parameters, including the slope of the rising section α , the circular curvature of the concave structure of the rising section is R sc , the length of the middle horizontal section is W sc1 , the length of the falling section is W sc2 , and the height is H sc ; S4: calculating the potential and field strength distribution in the stress cone structure and the surrounding air under different parameter combinations to obtain multiple sets of peak field strength in the stress cone structure E max_sc and the peak field strength in the air around the stress cone structure E max_air1 ; S5: selecting the stress cone structure parameter combination according to the multiple sets of peak field strength in the stress cone structure E max_sc and the peak field strength in the air around the stress cone structure E max_air1 , ensuring that the volume of the stress cone structure does not exceed the set minimum threshold E max_sc and E max_air1 is the lowest, and the stress cone structure parameter combination is taken as the preferred value of each structure parameter of the stress cone; S6: determining the value range of the umbrella skirt structure and the hollow structure parameters, including the height of the umbrella skirt structure H sh , the umbrella spacing D sh , the umbrella skirt angle θ , the number of umbrella skirts N , and the depth of the hollow structure D h and the width of the hollow structure W h ; S7: calculating multiple sets of creepage distances and electrical clearances under different umbrella skirt structure parameter combinations to verify whether they meet the requirements of the minimum creepage distance and electrical clearance; obtaining multiple sets of peak field strength in the insulation material of the hollow outgoing line end under different umbrella skirt structure and hollow structure parameter combinations E max1 , and the peak field strength at the cutoff of the ground shielding layerE max2 and the peak field strength of the bottom of the hollow structure E max3 ; S8: according to the multiple sets of creeping distance and electrical clearance obtained in S7, E max1 , E max2 and E max3 , select the umbrella skirt structure and hollow structure parameter combination to ensure that the volume of the umbrella skirt structure does not exceed the set minimum threshold while the longest creeping distance and electrical clearance and E max1 , E max2 and E max3 lowest, take the umbrella skirt structure and hollow structure parameter combination as the preferred value of each parameter of the umbrella skirt structure and hollow structure; complete the design.

[0009] Preferably, step S4 is specifically: according to the number of turns, wire diameter and arrangement of the winding structure, the thickness of the insulation material between the two lead wires of the high-voltage winding D isi , the thickness of the insulation material between the densely wound coil and the ground shielding layer D iso and the value range of the stress cone structure parameter determined in step S3, draw the high-voltage coil structure containing the stress cone structure but not containing the umbrella skirt structure and the hollow structure, apply voltage excitation on the high-voltage winding, the effective value of the voltage excitation is the design insulation strength, and the ground shielding layer applies ground potential; using finite element analysis method or numerical link calculation method to calculate the potential distribution and field strength distribution on the surface of the stress cone structure after cutting off from the ground shielding layer, and obtain the peak field strength E max_sc in the stress cone structure and the peak field strength E max_air1 in the air around the stress cone structure.

[0010] Preferably, step S7 is specifically: according to the number of turns, wire diameter and arrangement of the winding structure, the thickness of the insulation material between the two lead wires of the high-voltage winding D isi , the thickness of the insulation material between the densely wound coil and the ground shielding layer D iso, the preferred values of each parameter of the stress cone structure and the value range of the umbrella skirt structure parameter determined in step S6 draw a complete high-voltage winding structure, a voltage excitation is applied on the high-voltage winding, the effective value of the voltage excitation is the design insulation strength, the ground shielding layer is applied with a ground potential; the creepage distance and the electrical clearance from the hollowed-out terminal surface after the ground shielding layer is cut off to the high-voltage terminal of the high-voltage winding are calculated, and the peak field strength in the insulation material of the hollowed-out terminal is obtained by using a finite element analysis method or a numerical link calculation method E max1 , the peak field strength at the cut-off position of the ground shielding layer E max2 , and the peak field strength at the bottom of the hollowed-out structure E max3 .

[0011] Compared with the prior art, the beneficial effects of the present application are as follows: (1) The present application sets a hollowed-out structure at the terminal end of the terminal, so that the creepage distance and the electrical clearance between the high-voltage terminal and the ground potential are further extended on the basis of the overall length of the terminal, thereby realizing the reduction of the axial length of the terminal under the requirements of the electrical clearance and the creepage distance, and helping to further improve the power density of the high-voltage high-frequency transformer.

[0012] (2) Since the hollowed-out structure effectively shortens the axial length of the terminal, the mechanical stress generated in the connection area of the high-voltage winding main body structure and the terminal due to the lever effect is significantly reduced. At the same time, the hollowed-out structure design reduces the amount of casting insulation material, thereby reducing the overall weight of the terminal, thereby further enhancing the mechanical stability of the connection area and effectively ensuring the reliability of the long-term operation of the insulation system.

[0013] (3) Since the stress cone structure is provided at the cut-off position of the ground shielding layer, the problem of surface discharge caused by the three-state interface composed of air, conductor and insulation medium is effectively suppressed. At the same time, the stress cone structure and the main insulation layer are integrally formed by casting process, which is not only convenient to process, but also keeps the shielding performance stable under long-term operation conditions, thereby realizing the high reliability design of the terminal insulation.

[0014] (4) Since the semi-conductive coating is used as the ground shielding layer, the equipotential shielding effect is realized, the eddy current loss of the shielding layer itself is effectively avoided, and good wettability between the main insulation casting material and the shielding layer is ensured.

[0015] (5) This invention achieves a uniform distribution of electric field stress at the outlet of the high-voltage coil by synergistically optimizing the cone angle of the stress cone structure, the curvature of the concave arc of the stress cone structure, the spacing of the umbrella skirt structure, and the depth of the hollow structure. Its beneficial effects are: while maintaining a compact overall volume, it effectively suppresses local peak field stress and improves the insulation safety margin; thus, while meeting and exceeding national standard requirements, it reduces the cost of insulation materials and significantly improves the power density of the whole machine. Attached Figure Description

[0016] Figure 1 This is a design drawing for the insulation of the output terminals of a high-frequency transformer designed for medium and low voltage levels. Figure 2 This is a design drawing for the insulation of the output terminals of a conventional high-voltage high-frequency transformer. Figure 3 This is a cross-sectional view of the high-voltage coil structure of the high-voltage high-frequency transformer of the present invention; Figure 4 This is a three-dimensional schematic diagram of the high-voltage coil structure of the high-voltage high-frequency transformer of the present invention; Figure 5 This is a flowchart illustrating the design process of the high-voltage coil structure of the high-voltage high-frequency transformer of the present invention. Figure 6 This is a diagram showing the equipotential line distribution inside and around the high-voltage transformer under 45kV excitation. Detailed Implementation

[0017] The present invention will be further described and illustrated below with reference to specific embodiments. The technical features of each embodiment of the present invention can be combined accordingly, provided that there is no mutual conflict.

[0018] This invention first provides a high-voltage coil structure for a high-voltage high-frequency transformer, such as... Figure 3 and Figure 4 As shown, it includes a main structure integrally vacuum-cast from insulating material and a hollowed-out lead end; a closely wound coil is disposed within the main structure, and the side wall of the hollowed-out lead end is provided with a full circumference of stress cone structure and umbrella skirt structure from back to front, and a hollowed-out structure for increasing creepage distance and electrical clearance is provided on the front end face of the hollowed-out lead end; two leads are led out from the closely wound coil, and the two leads pass parallel through the interior of the hollowed-out lead end to the bottom surface of the hollowed-out structure, and a high voltage excitation is applied to the closely wound coil and the two leads, thus forming a high-voltage winding. Let the differential mode voltage between the two lead ends be V.

[0019] The insulating material is made of epoxy resin or silicone, vacuum-cast onto the outside of the high-voltage winding structure, filling the entire main structure of the high-voltage coil and the interior of the hollowed-out leads. It also forms a hollow inner ring inside the tightly wound coil, which serves as the passageway for the magnetic core pillars of the high-voltage high-frequency transformer. The thickness of the insulating material between the tightly wound coil and the grounding shield layer...D iso satisfy ; in, V DIL To design insulation strength, k saf For safety reasons, E ref This is the nominal breakdown field strength of the insulating material. d ref The thickness of the insulating material corresponding to the nominal breakdown field strength. n This is the attenuation coefficient of the breakdown field strength as the thickness of the insulating material increases.

[0020] The stress cone structure is located adjacent to the main structure of the high-voltage coil and is used to avoid severe distortion of the electric field distribution along the outer surface of the hollowed-out wire end. The stress cone structure includes a rising section, a horizontal section, and a falling section, wherein the rising section includes a section of arc-shaped concave structure; let the slope of the rising section be... α The curvature of the concave structure in the rising segment is R sc， The length of the middle horizontal section is W sc1 The length of the descent segment is W sc2 The height of the stress cone structure is H sc .

[0021] The umbrella skirt structure is provided in multiple parts, and the multiple umbrella skirt structures are evenly distributed up to the front end of the high-voltage coil structure. The umbrella skirt structure can increase the creepage distance. Let the height of the umbrella skirt structure be... H sh The distance between umbrellas is D sh The angle of the umbrella skirt is θ The number of umbrella skirts is N .

[0022] The grounding shielding layer uses a semi-conductive coating, applied to the outer surface of the insulating material of the main structure, and extending to the junction of the rising and horizontal sections of the stress cone structure (i.e., the concave section of the stress cone structure). By creating this concave structure, the electric field at the cutoff point of the grounding shielding layer is effectively homogenized, smoothing the distribution of equipotential lines and thus preventing local discharge caused by stress concentration. While achieving equipotential shielding, the semi-conductive coating effectively avoids eddy current losses within the shielding layer itself and ensures good wettability with the insulating material.

[0023] The hollow structure is a cavity carved out at the end of the high-voltage coil structure. Let the depth of the hollow structure be... D h Width isW h .

[0024] This invention also provides a design method based on the aforementioned high-voltage coil structure of a high-voltage high-frequency transformer, such as... Figure 5 It includes the following steps: S1: Determine the design insulation strength of the high-voltage high-frequency transformer according to design requirements, and determine the minimum creepage distance and minimum electrical clearance according to GB 1094.11 "Power Transformers Part 11: Dry-type Transformers" standard; S2: Based on the differential mode voltage between the two leads of the high-voltage winding V Determine the thickness of the insulation material between leads according to IEC 62477-1:2022. D isi The thickness of the insulating material between the closely wound coil and the grounding shield is determined based on the design insulation strength of the high-voltage high-frequency transformer. ; S3: Determine the range of values ​​for the stress cone structure parameters based on experience. The stress cone structure parameters include the slope of the rising section. α The curvature of the concave structure in the rising segment is R sc Length of the middle horizontal section W sc1 Length of descent segment W sc2 and height H sc ; S4: Based on parameters such as the number of turns, wire diameter, and arrangement of the winding structure, and the thickness of the insulation layer between the two leads of the high-voltage winding. D isi The thickness of the insulation material between the tightly wound coil and the grounding shield layer D iso Based on the range of values ​​for the stress cone structure parameters determined in step S3, a high-voltage coil structure including the stress cone structure but excluding the umbrella skirt structure and the hollow structure is drawn. Voltage excitation is applied to the high-voltage winding, with the effective value of the voltage excitation being the design insulation strength. Ground potential is applied to the grounding shield layer. The potential distribution and field strength distribution along the surface of the stress cone structure after the grounding shield layer is cut off are calculated using finite element analysis or numerical link calculation methods, and the peak field strength within the stress cone structure is obtained. E max_sc and the peak field strength in the air surrounding the stress cone structure E max_air1 ; S5: Peak field strength within multiple stress cone structures obtained from S4 E max_sc and the peak field strength in the air surrounding the stress cone structure E max_air1By selecting a suitable combination of stress cone structural parameters, the volume of the stress cone structure can be ensured to not exceed the set minimum threshold. E max_sc and E max_air1 At the very least, the combination of the stress cone structural parameters is taken as the preferred value of each structural parameter of the stress cone; S6: Referring to the relevant requirements of IEC 60815 and considering the casting process to ensure the mechanical strength of the umbrella skirt structure, determine the approximate value range of the parameters for the umbrella skirt structure and the perforated structure. The parameters for the umbrella skirt structure and the perforated structure include the height of the umbrella skirt structure. H sh Umbrella spacing D sh Umbrella skirt angle θ Number of umbrella skirts N and the depth of the hollow structure D h and width W h ; S7: Based on parameters such as the number of turns, wire diameter, and arrangement of the winding structure, and the thickness of the insulation layer between the two leads of the high-voltage winding. D isi Main insulation layer thickness D iso The optimal values ​​of each parameter of the stress cone structure and the value range of the umbrella skirt structure parameters determined in step S6 are used to draw the complete high-voltage coil structure. Voltage excitation is applied to the high-voltage winding, and the effective value of the voltage excitation is the design insulation strength. Ground potential is applied to the grounding shield layer. The creepage distance and electrical clearance from the surface of the hollowed-out end of the grounding shield layer to the high-voltage terminal of the high-voltage winding are calculated. The peak electric field strength in the insulation material of the hollowed-out end is obtained by finite element analysis or numerical link calculation. E max1 Peak electric field strength at the grounding shield cutoff point E max2 Peak electric field strength at the bottom of the hollow structure E max3 ; S8: Based on the multiple sets of creepage distances and clearances obtained in S7, E max1 , E max2 and E max3 By selecting appropriate combinations of umbrella skirt structure and perforation structure parameters, while ensuring that the umbrella skirt structure does not exceed the set minimum threshold, the creepage distance and clearance are maximized. E max1 , E max2 and Emax3 At the very least, the combination of parameters for the umbrella skirt structure and the hollow structure is used to obtain the optimal values ​​for each parameter of the umbrella skirt structure and the hollow structure; thus completing the design.

[0025] To fully demonstrate the advantages of the high-voltage coil structure proposed in this invention, a 35kV insulation class high-voltage coil is used as an example for explanation. The minimum electrical clearance and creepage distance at the outgoing end of this high-voltage coil are set according to standards GB 1094.11 "Power Transformers Part 11: Dry-type Transformers" and IEC 62477-2:2018. Table 1 compares the outgoing end lengths of conventional high-voltage coil structures and the high-voltage coil structure described in this invention. The results show that the hollowed-out outgoing structure proposed in this invention can shorten the outgoing length by approximately 17.8%, effectively improving the power density of the high-voltage coil and the high-voltage high-frequency transformer as a whole. Simultaneously, the hollowed-out structure at the outgoing end significantly reduces the overall weight of the high-voltage coil, enhances the mechanical stability of the connection between the main structure of the high-voltage coil and the outgoing end, and is beneficial to ensuring the long-term reliable operation of the high-voltage coil insulation system of the high-voltage high-frequency transformer.

[0026] Table 1 To further verify the reliability of the high-voltage coil structure proposed in this invention in terms of insulation system, a corresponding finite element simulation model was established, such as... Figure 6 As shown, the analysis also takes a 35kV insulation class high-voltage transformer as an example. According to the GB1094.11 standard "Power Transformers Part 11: Dry-type Transformers", a 35kV insulation class dry-type transformer must pass a power frequency withstand voltage test with an amplitude of 70kV and a duration of not less than 1 minute, and meet the requirement that the partial discharge quantity is less than 10pC at a voltage of 45kV.

[0027] Power frequency withstand voltage tests can usually be met by ensuring sufficient insulation thickness and good casting quality. However, the electric field distribution within the insulation system is often non-uniform, easily generating peak electric fields exceeding the design field strength limit of air in local areas, leading to a significant increase in the risk of partial discharge. Therefore, the simulation process focuses on analyzing the peak electric field distribution in the insulation system under 45kV voltage to ensure that its maximum value is lower than the design field strength limit of each insulation material, thereby meeting the standard requirements for partial discharge performance.

[0028] Figure 6The diagram illustrates the distribution of equipotential lines within a high-voltage coil under 45kV excitation, with their density directly reflecting the electric field strength distribution. Three key points are highlighted in the diagram as areas of electric field distortion requiring close attention during the design process: Point 1, located inside the main insulation layer, has a peak electric field strength of 3.4 kV / mm, lower than the commonly used design field strength limit (6~7 kV / mm) for the main insulation material (epoxy resin); Points 2 and 3 are located at the grounding shield cutoff and the bottom of the hollow structure, respectively. Both are situated in the three-state interface region formed by "conductor-insulating medium-air," representing high-risk locations for surface flashover. The peak electric field strengths at the grounding shield cutoff and the bottom of the hollow structure are 0.8 kV / mm and 1.5 kV / mm, respectively, both lower than the design field strength limit of 1.5~2 kV / mm for air. In summary, it can be seen that the hollowed-out wire structure proposed in this invention has sufficient design margin in electric field strength at key locations under 45kV voltage, which can effectively suppress the risk of partial discharge and surface flashover, meet the strict requirements of the standard for partial discharge level, and verify the high reliability of the insulation structure under actual operating conditions.

[0029] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the appended claims.

Claims

1. A high-voltage coil structure for a high-voltage high-frequency transformer, characterized in that, The device includes a main structure integrally vacuum-cast from insulating material and a hollowed-out lead end. A tightly wound coil is disposed within the main structure. From back to front, the sidewalls of the hollowed-out lead end are sequentially provided with a stress cone structure and a skirt structure. A hollowed-out structure for increasing creepage distance and clearance is provided on the front end of the hollowed-out lead end. The stress cone structure includes a rising section, a horizontal section, and a falling section, wherein the rising section includes a section of arc-shaped concave structure. Two leads are drawn from the tightly wound coil, passing through the interior of the hollowed-out lead end to the bottom surface of the hollowed-out structure. The outer surface of the main structure is coated with a grounding shielding layer, which extends and covers part of the stress cone structure area.

2. The high-voltage coil structure according to claim 1, characterized in that, The material of the tightly wound coil and its leads is Litz wire, copper foil, or enameled wire.

3. The high-voltage coil structure according to claim 1, characterized in that, The insulating material is epoxy resin or silicone, and the thickness of the insulating material between the tightly wound coil and the grounding shield layer is... satisfy ； in, V DIL To design insulation strength, k saf For safety reasons, E ref This is the nominal breakdown field strength of the insulating material. d ref The thickness of the insulating material corresponding to the nominal breakdown field strength. n This is the attenuation coefficient of the breakdown field strength as the thickness of the insulating material increases.

4. The high-voltage coil structure according to claim 1, characterized in that, The grounding shielding layer is made of semi-conductive coating and ends at the junction of the rising and horizontal sections of the stress cone structure.

5. The high-voltage coil structure according to claim 1, characterized in that, The umbrella skirt structure is provided in multiple ways, and the multiple umbrella skirt structures are evenly distributed up to the front end of the high voltage coil.

6. The high-voltage coil structure according to claim 1, characterized in that, The two leads of the tightly wound coil pass parallel through the inside of the hollowed-out end to the bottom surface of the hollowed-out structure.

7. The high-voltage coil structure according to claim 1, characterized in that, The insulating material forms a hollow inner ring inside the tightly wound coil, which serves as the passage for the magnetic core column of the high-voltage high-frequency transformer.

8. A design method for the high-voltage coil structure of a high-voltage high-frequency transformer as described in claim 3, characterized in that, Includes the following steps: S1: Determine the design insulation strength, minimum creepage distance, and minimum clearance of the high-voltage high-frequency transformer; S2: Based on the differential mode voltage between the two leads of the high-voltage winding V Determine the thickness of the insulation material between leads D isi The thickness of the insulating material between the closely wound coil and the grounding shield is determined based on the design insulation strength of the high-voltage high-frequency transformer. D iso ; S3: Determine the value range of the stress cone structure parameters, including the slope of the rising section. α The curvature of the concave structure in the rising segment is R sc Length of the middle horizontal section W sc1 Length of descent segment W sc2 and height H sc ; S4: Calculate the potential and field strength distribution in the stress cone structure and surrounding air under different parameter combinations, and obtain the peak field strength in multiple sets of stress cone structures. E max_sc and the peak field strength in the air surrounding the stress cone structure E max_air1 ; S5: Peak field strength within multiple stress cone structures obtained from S4 E max_sc and the peak field strength in the air surrounding the stress cone structure E max_air1 Select a combination of stress cone structure parameters to ensure that the volume of the stress cone structure does not exceed a set minimum threshold. E max_sc and E max_air1 At the very least, the combination of the stress cone structural parameters is taken as the preferred value of each structural parameter of the stress cone; S6: Determine the value range of the parameters for the umbrella skirt structure and the hollow structure, including the height of the umbrella skirt structure. H sh Umbrella spacing D sh Umbrella skirt angle θ Number of umbrella skirts N and the depth of the hollow structure D h and width W h ; S7: Calculate multiple sets of creepage distances and clearances under different combinations of umbrella skirt structure parameters, and verify whether they meet the requirements for minimum creepage distances and clearances; obtain the peak electric field intensity within the insulation material of multiple sets of hollowed-out wire terminals under different combinations of umbrella skirt structure and hollowed-out structure parameter combinations. E max1 Peak electric field strength at the grounding shield cutoff point E max2 Peak electric field strength at the bottom of the hollow structure E max3 ; S8: Based on the multiple sets of creepage distances and clearances obtained in S7, E max1 , E max2 and E max3 By selecting a combination of parameters for the umbrella skirt structure and the hollow structure, the volume of the umbrella skirt structure is ensured to not exceed the set minimum threshold, while maximizing the creepage distance and clearance. E max1 , E max2 and E max3 At the very least, the combination of parameters for the umbrella skirt structure and the hollow structure is used to obtain the optimal values ​​for each parameter of the umbrella skirt structure and the hollow structure; thus completing the design.

9. The design method according to claim 8, characterized in that, Step S4 specifically involves: determining the number of turns, wire diameter, and arrangement of the winding structure, as well as the thickness of the insulation material between the two leads of the high-voltage winding. D isi The thickness of the insulation material between the tightly wound coil and the grounding shield layer D iso Based on the range of values ​​for the stress cone structure parameters determined in step S3, a high-voltage coil structure including the stress cone structure but excluding the umbrella skirt structure and the hollow structure is drawn. Voltage excitation is applied to the high-voltage winding, with the effective value of the voltage excitation being the design insulation strength. Ground potential is applied to the grounding shield layer. The potential distribution and field strength distribution along the surface of the stress cone structure after the grounding shield layer is cut off are calculated using finite element analysis or numerical link calculation methods, and the peak field strength within the stress cone structure is obtained. E max_sc and the peak field strength in the air surrounding the stress cone structure E max_air1 .

10. The design method according to claim 9, characterized in that, Step S7 specifically involves: determining the number of turns, wire diameter, and arrangement of the winding structure, as well as the thickness of the insulation material between the two leads of the high-voltage winding. D isi The thickness of the insulation material between the tightly wound coil and the grounding shield layer D iso The optimal values ​​of each parameter of the stress cone structure and the value range of the umbrella skirt structure parameters determined in step S6 are used to draw the complete high-voltage coil structure. Voltage excitation is applied to the high-voltage winding, and the effective value of the voltage excitation is the design insulation strength. Ground potential is applied to the grounding shield layer. The creepage distance and electrical clearance from the surface of the hollowed-out end of the grounding shield layer to the high-voltage terminal of the high-voltage winding are calculated. The peak electric field strength in the insulation material of the hollowed-out end is obtained by finite element analysis or numerical link calculation. E max1 Peak electric field strength at the grounding shield cutoff point E max2 Peak electric field strength at the bottom of the hollow structure E max3 .

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