Glue-free conical high-voltage pulse transformer secondary coil and preparation method thereof

Abstract

The invention discloses a glue-free conical high-voltage pulse transformer secondary coil and a preparation method thereof, and solves the technical problems that electromagnetic wires are easy to discharge due to the adoption of curing glue in the existing conical high-voltage pulse transformer secondary coil, and the operation stability of the secondary coil is poor. The secondary coil is only composed of the paper base cylinder and the coil winding layer, the structure is simpler, the winding process is more convenient, and uncertainty caused by human factors is reduced; the coil winding layer and the miniature spiral wire groove are mutually embedded, so that accurate arrangement, uniformity and stability of electromagnetic wires are realized, no gelling is realized, and the problems of non-uniformity of an electric field and a closed air gap possibly caused by introduction of resin glue and insulation possibly caused by introduction of the resin glue are avoided.

Description

Technical Field

[0001] This invention relates to secondary coils and their preparation methods, specifically to a glue-free tapered high-voltage pulse transformer secondary coil and its preparation method. Background Technology

[0002] Tesla transformer-type pulsed power drives are widely used in high-power microwave applications. Their main characteristic is the integrated construction of the Tesla transformer and pulse forming line—the primary and secondary coils of the Tesla transformer are embedded within the coaxial pulse forming line, between open-circuit magnetic cores. Energy stored in the primary capacitor is stored as an electric field within the pulse forming line through the coupled resonance of the primary and secondary coils of the Tesla transformer. This energy is then compressed by a gas switch to output high-power electrical pulses. However, when the Tesla transformer charges the pulse forming line, the voltage across the secondary coil gradually increases. If a discharge occurs at a point causing a breakdown, the electromagnetic wires in the coil conductors will break within a short time, rendering the transformer malfunction.

[0003] Currently, secondary coils are known to have two structures: conical and cylindrical. Conical coils do not affect the formation of line impedance distribution and are therefore widely used. Common conical secondary coils consist of electrical cardboard, conductors, and curing adhesive. The cardboard surface is coated with adhesive, which, after curing, bonds the conductors to the cardboard. During the winding process of the conical secondary coil, the adhesive layer covering the cardboard surface easily creates a sealed air gap. Experimental studies show that the electric field within this air gap is significantly enhanced. This air gap is most likely to experience gas discharge, forming a small-scale "explosion," causing multi-turn conductors to bulge outwards or even break. Furthermore, the dielectric constant of the curing adhesive is not consistent with that of the transformer oil. The introduction of the curing adhesive causes local distortion of the electric field near the conductors due to the inhomogeneity of the dielectric constants of the transformer oil and the curing adhesive, making inter-turn discharge more likely at localized points. Therefore, to ensure the reliability of the secondary coil operation, it is necessary to avoid the formation of sealed air gaps and inhomogeneous dielectric constants.

[0004] On the other hand, the coil vibrates under strong pulsed current during operation. Under long-term vibration, the conductors and electromagnetic wires may detach or shift, leading to a decrease in the inter-turn insulation distance and thus causing inter-turn discharge. Therefore, to ensure the long-term operational stability of the coil, it is necessary to ensure the uniformity and stability of the conductor and electromagnetic wire arrangement within the coil. Summary of the Invention

[0005] The purpose of this invention is to solve the technical problem that the use of curing adhesive in the secondary coil of existing conical high-voltage pulse transformers leads to easy discharge between electromagnetic wires, resulting in poor operating stability of the secondary coil. The invention provides a glue-free conical high-voltage pulse transformer secondary coil and its preparation method.

[0006] To achieve the above objectives, the technical solution provided by this invention is as follows:

[0007] A glue-free conical high-voltage pulse transformer secondary coil is characterized by comprising a coaxially arranged paper base tube and a coil winding layer.

[0008] The paper base tube is a paper conical structure prepared by a wet integral molding process;

[0009] The outer wall of the paper base tube is provided with a micro spiral groove, and the coil winding layer is made of electromagnetic wire, with the electromagnetic wire embedded in the micro spiral groove.

[0010] Furthermore, the cross-sectional shape of the micro spiral groove is trapezoidal, and the width gradually narrows from the bottom to the opening of the groove, while the depth is not less than the diameter of the electromagnetic wire in the coil winding layer.

[0011] Furthermore, the cross-sectional shape of the micro spiral groove is rectangular, and its depth is not less than the diameter of the electromagnetic wire in the coil winding layer.

[0012] A method for fabricating the secondary coil of a glue-free tapered high-voltage pulse transformer, characterized by the following steps:

[0013] S1. Make a vacuum mold according to the required size of the paper base tube. Cover the surface of the vacuum mold with nylon mesh. Apply the cut wet paper blank to the surface of the vacuum mold multiple times evenly. Press, vacuum, dry, and trim the edges in sequence. Remove the paper base tube.

[0014] S2. Using a CNC lathe, select the groove width and corresponding cutting head according to the diameter of the electromagnetic wire, and carve a micro spiral groove on the conical surface of the paper base cylinder.

[0015] S3. According to the actual winding direction requirements of the high-voltage pulse transformer, fix the electromagnetic wire to one end of the paper base tube, pull the electromagnetic wire forcefully to gradually press the electromagnetic wire into the micro spiral groove until the other end of the paper base tube, and obtain the coil winding layer.

[0016] Furthermore, S1 specifically refers to:

[0017] S1.1. Make a vacuum mold according to the required size of the paper base tube, and cover the surface of the vacuum mold with nylon mesh;

[0018] S1.2. Apply the cut wet paper blanks evenly to the surface of the vacuum mold in multiple batches. After each application, use an elastic band to press it tight, draw a vacuum, and maintain it for 20-24 hours to make the paper tube initially formed.

[0019] S1.3 Place the pre-formed paper tube together with the mold in a drying oven, set the temperature to 120℃-125℃, and dry for 46h-48h. Remove it and tighten it again with an elastic band, then put it back into the drying oven to continue drying for 48 hours. Trim the edges and complete the finishing and surface polishing, then remove the paper base tube.

[0020] Furthermore, in S1, the length and outer diameter of the vacuum mold are the same as the length and inner diameter of the required paper base cylinder, and the material is aluminum;

[0021] One end of the vacuum mold is sealed, and the other end has a vacuum interface for connecting to a vacuum pumping device. Multiple ventilation holes are evenly distributed on the side wall of the vacuum mold for vacuuming the inner surface of the wet paper blank.

[0022] Further, S3 specifically involves: coaxially fixing one end of the paper base tube to the output shaft of the rotating device; fixing the electromagnetic wire to one end of the paper base tube according to the actual winding direction requirements of the high-voltage pulse transformer; starting the rotating device to make the paper base tube rotate around the central axis; pulling the electromagnetic wire forcefully to gradually press the electromagnetic wire into the micro spiral groove until the other end of the paper base tube is reached, thus obtaining the coil winding layer.

[0023] Compared with the prior art, the present invention has the following beneficial technical effects:

[0024] 1. This invention provides a glue-free conical high-voltage pulse transformer secondary coil and its preparation method, which consists of only two parts: a paper base and a coil winding layer. The structure is simpler, the winding process is more convenient, and the uncertainty introduced by human factors is reduced.

[0025] 2. This invention provides a glue-free conical high-voltage pulse transformer secondary coil and its preparation method, which achieves glue-free operation and avoids the uneven electric field and air gap that may be caused by the introduction of resin glue, as well as the insulation problems that may be caused by it.

[0026] 3. This invention provides a glue-free conical high-voltage pulse transformer secondary coil and its preparation method. The coil winding layer and the micro spiral groove are interlocked, realizing the precise, uniform and stable arrangement of electromagnetic wires. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the structure of a secondary coil of a glue-free conical high-voltage pulse transformer according to an embodiment of the present invention;

[0028] Figure 2 This is a schematic diagram of the paper base tube in an embodiment of the secondary coil of a glue-free conical high-voltage pulse transformer according to the present invention;

[0029] Figure 3This is a schematic diagram of the trapezoidal cross-sectional shape of the miniature spiral groove in an embodiment of the secondary coil of a glue-free conical high-voltage pulse transformer of the present invention.

[0030] Figure 4 This is a schematic diagram of the rectangular cross-sectional shape of the miniature spiral groove in an embodiment of the secondary coil of a glue-free conical high-voltage pulse transformer of the present invention.

[0031] The annotations in the attached figures are explained as follows:

[0032] 1-Paper base tube; 2-Coil winding layer; 3-Miniature spiral groove. Detailed Implementation

[0033] To make the objectives, advantages, and features of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Those skilled in the art should understand that these embodiments are merely used to explain the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0034] This embodiment provides a glue-free tapered high-voltage pulse transformer secondary coil, such as... Figure 1 As shown, it includes a paper base tube 1, a coil winding layer 2, and a micro-spiral groove 3; wherein, the paper base tube 1 is a paper conical structure prepared by a wet integral molding process; as shown Figure 2 As shown, the outer wall of the paper base cylinder 1 is provided with a micro spiral groove 3, and the coil winding layer 2 is made of electromagnetic wire, with the electromagnetic wire embedded in the micro spiral groove 3. The paper base cylinder 1, the coil winding layer 2 and the micro spiral groove 3 are coaxially arranged. In this embodiment, the secondary coil is formed by the paper base cylinder 1 and the coil winding layer 2, which makes the structure simpler, the preparation process more convenient, and reduces the uncertainty introduced by human factors.

[0035] Meanwhile, the coil winding layer 2 is embedded in the micro spiral groove 3 to fix the coil winding layer 2. The coil winding layer 2 is formed by winding electromagnetic wire, which realizes the precise, uniform and stable arrangement of electromagnetic wire; and the adjacent coils are insulated by paper, which can avoid the uneven electric field and air gap that may be caused by the introduction of resin glue, and the insulation problems that may be caused by it; by effectively preventing discharge between electromagnetic wires, the stability of operation is improved.

[0036] like Figure 3 As shown, the cross-sectional shape of the miniature spiral groove 3 is trapezoidal, and its width gradually narrows from the bottom to the opening, while its depth is not less than the diameter of the electromagnetic wire in the coil winding layer 2. Figure 4 As shown, the cross-sectional shape of the miniature spiral groove 3 is rectangular, and its depth is not less than the diameter of the electromagnetic wire forming the coil winding layer 2. The miniature spiral groove 3 is designed to be rectangular or trapezoidal to facilitate clamping and fixing after the electromagnetic wire is pressed in, preventing it from loosening and skipping.

[0037] This embodiment also provides a method for preparing the secondary coil of a glue-free tapered high-voltage pulse transformer, including the following steps:

[0038] S1. First, a vacuum mold is made according to the required size of the paper base tube 1. The surface of the vacuum mold is covered with nylon mesh. The length and outer diameter of the vacuum mold are the same as the length and inner diameter of the required paper base tube 1. The material is 6010 aluminum. One end of the vacuum mold is sealed, and the other end is opened with a vacuum interface. The vacuum interface is used to connect to a vacuum pumping device. Multiple ventilation holes are evenly opened on the side wall. The multiple ventilation holes are used to vacuum the inner surface of the wet paper blank.

[0039] Subsequently, the cut wet paper blanks are evenly applied to the surface of the vacuum mold in two batches. After each application, an elastic band is used to press it tight, and a vacuum is drawn to maintain the process for 20-24 hours, so that the paper tube is initially formed.

[0040] Next, place the pre-formed paper tube along with the mold in a drying oven, set the temperature to 120℃-125℃, and dry for 46h-48h before removing it; tighten it again with an elastic band and place it back in the drying oven to continue drying for 48 hours before removing it; trim the edges and complete the finishing and surface polishing, then remove the paper base tube 1.

[0041] S2. Using a CNC lathe, select the groove width and corresponding cutting head according to the diameter of the electromagnetic wire, and carve a micro spiral groove 3 on the conical surface of the paper base cylinder 1.

[0042] S3. Coaxially fix one end of the paper base tube 1 to the output shaft of the rotating device. According to the actual winding direction requirements of the high voltage pulse transformer, fix the electromagnetic wire to one end of the paper base tube 1. Start the rotating device to make the paper base tube 1 rotate around the central axis. Pull the electromagnetic wire to gradually press the electromagnetic wire into the micro spiral groove 3 until the other end of the paper base tube 1 is reached, and the coil winding layer 2 is obtained.

[0043] The method for preparing the secondary coil of the glue-free conical high-voltage pulse transformer in this embodiment can be used to prepare two secondary coils forming a nested double-conical coil for use in Tesla transformers. Specific parameters are as follows:

[0044] In the double-cone coil, the thickness of the paper base tube 1 of both the inner and outer cones is 1.5mm; the diameters of the two ends of the paper base tube 1 of the outer cone are 1149mm and 863mm respectively, and the length is 1470mm; the diameters of the two ends of the paper base tube 1 of the inner cone are 846mm and 627mm respectively, and the length is 1470mm; the diameter of the electromagnetic wire wound into the coil winding layer 2 of the inner and outer cones is 0.6mm, the depth of the micro spiral groove is 0.8mm, the width is 0.65mm, the spiral spacing is 1.45mm, and the total number of turns is 1984 turns; the operating voltage of the secondary coil of the Tesla transformer exceeds 1.5MV, and the lifespan expressed in pulse count exceeds 1 million. Therefore, it can be seen that the secondary coil used in this embodiment has good stability.

[0045] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the present invention.

Claims

1. A glue-free conical high-voltage pulse transformer secondary coil, characterized in that: It includes a paper base tube (1) and a coil winding layer (2) arranged coaxially. The paper base tube (1) is a paper conical structure prepared by a wet integral molding process; The outer wall of the paper base tube (1) is provided with a micro spiral groove (3), and the coil winding layer (2) is made of electromagnetic wire, and the electromagnetic wire is embedded in the micro spiral groove (3).

2. The secondary coil of a glue-free conical high-voltage pulse transformer according to claim 1, characterized in that: The cross-sectional shape of the micro spiral groove (3) is trapezoidal, and the width gradually narrows from the bottom of the groove to the opening of the groove, and the depth is not less than the electromagnetic wire diameter of the coil winding layer (2).

3. The secondary coil of a glue-free conical high-voltage pulse transformer according to claim 1, characterized in that: The cross-sectional shape of the micro spiral groove (3) is rectangular, and its depth is not less than the diameter of the electromagnetic wire of the coil winding layer (2).

4. A method for preparing the secondary coil of a glue-free conical high-voltage pulse transformer according to any one of claims 1-3, characterized in that, Includes the following steps: S1. Make a vacuum mold according to the required size of the paper base tube (1), cover the surface of the vacuum mold with nylon mesh, apply the cut wet paper blank to the surface of the vacuum mold multiple times evenly, and then press, vacuum, dry, and trim the edges in sequence, and remove the paper base tube (1). S2. Using a CNC lathe, select the groove width and corresponding cutting head according to the diameter of the electromagnetic wire, and carve a micro spiral groove (3) on the conical surface of the paper base cylinder (1). S3. According to the actual winding direction requirements of the high voltage pulse transformer, fix the electromagnetic wire to one end of the paper base tube (1), pull the electromagnetic wire with force, so that the electromagnetic wire is gradually pressed into the micro spiral groove (3) until the other end of the paper base tube (1) to obtain the coil winding layer (2).

5. The method for preparing the secondary coil of a glue-free conical high-voltage pulse transformer according to claim 4, characterized in that, S1 specifically refers to: S1.

1. Make a vacuum mold according to the required size of the paper base tube (1), and cover the surface of the vacuum mold with nylon mesh; S1.

2. Apply the cut wet paper blanks evenly to the surface of the vacuum mold in multiple batches. After each application, use an elastic band to press it tight, draw a vacuum, and maintain it for 20-24 hours to make the paper tube initially formed. S1.3 Place the pre-formed paper tube together with the mold in a drying oven, set the temperature to 120℃-125℃, and dry for 46h-48h before taking it out; tighten it again with an elastic band and put it back into the drying oven to continue drying for 48 hours before taking it out; trim the edges and complete the finishing and surface polishing, and remove the paper base tube (1).

6. The method for preparing the secondary coil of a glue-free conical high-voltage pulse transformer according to claim 4 or 5, characterized in that: In S1, the length and outer diameter of the vacuum mold are the same as the length and inner diameter of the required paper base cylinder (1), and the material is aluminum; One end of the vacuum mold is sealed, and the other end has a vacuum interface for connecting to a vacuum pumping device. Multiple ventilation holes are evenly distributed on the side wall of the vacuum mold for vacuuming the inner surface of the wet paper blank.

7. The method for preparing the secondary coil of a glue-free conical high-voltage pulse transformer according to claim 4 or 5, characterized in that, S3 specifically involves: coaxially fixing one end of the paper base tube (1) to the output shaft of the rotating device; fixing the electromagnetic wire to one end of the paper base tube (1) according to the actual winding direction requirements of the high-voltage pulse transformer; starting the rotating device to make the paper base tube (1) rotate around the central axis; pulling the electromagnetic wire to gradually press the electromagnetic wire into the micro spiral groove (3) until the other end of the paper base tube (1) is reached, thus obtaining the coil winding layer (2).

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