Medium-high frequency epoxy resin pouring dry-type transformer
By setting the first airway between the high-voltage winding and the low-voltage winding of the transformer and a second airway in a honeycomb coal shape on the winding, the problem of poor heat dissipation of the low-voltage winding is solved, and the overall heat dissipation performance and structural strength of the transformer are improved .
Patent Information
- Application Number
- CN202421636653.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-07-11
- Publication Date
- 2025-02-07
- Estimated Expiration
- 2034-07-11
AI Technical Summary
In existing epoxy resin cast dry transformers, the heat dissipation effect of the low-voltage winding is poor, which affects the heat dissipation performance of the entire transformer.
A first airway is provided between the high-pressure winding and the low-pressure winding, and a honeycomb coal-shaped second airway is arranged along the circumference of the first airway on the low-pressure winding or the high-pressure winding, so that efficient heat dissipation is achieved using these two airways.
By adding the second air duct, the heat dissipation ability of the transformer is improved, the heat dissipation effect of the low-voltage winding is improved, and the structural strength of the high-low-voltage winding is ensured.
Smart Images
Figure CN222440318U_ABST
Abstract
Description
Technical Field
[0001] The utility model belongs to the technical field of transformers, and in particular relates to a medium-high frequency epoxy resin cast dry-type transformer. Background Art
[0002] Existing epoxy resin cast dry-type transformers usually include iron cores, high and low voltage windings, high and low voltage terminals, spacers, clamps, etc. The heat dissipation of traditional dry-type transformers mainly depends on the air ducts set between the high and low voltage windings, and the air ducts are used to take away the heat of the high and low voltage windings and the heat between them. However, the low voltage winding is located on the inner side of the high voltage winding, and the heat dissipation effect is not as good as that of the high voltage winding. The traditional method of only setting an air duct between the high and low voltage windings is not conducive to the heat dissipation of the low voltage winding, which ultimately affects the heat dissipation of the entire transformer. Utility Model Content
[0003] In view of the above problems in the prior art, the present application proposes a medium-high frequency epoxy resin cast dry-type transformer, which improves the heat dissipation capacity of the winding by adding a second air duct to the winding.
[0004] The utility model proposes a medium-high frequency epoxy resin cast dry-type transformer, comprising an iron core, a high-voltage winding, a low-voltage winding, a clamp and a mounting base; the low-voltage winding is surrounded by the outer periphery of the iron core; the high-voltage winding is surrounded by the outer periphery of the low-voltage winding, and a distance is maintained between the high-voltage winding and the low-voltage winding to form a first annular air duct; a plurality of silicone rods are arranged at intervals along the circumferential direction in the first air duct, and the silicone rods are supported between the high-voltage winding and the low-voltage winding; a honeycomb-like second air duct arranged circumferentially along the first air duct is provided on the low-voltage winding and / or the high-voltage winding; the clamp is clamped at both ends of the iron core, and the mounting base is connected to the clamp.
[0005] Further, the second air channel includes a plurality of through holes, and the plurality of through holes are arranged at intervals along the circumference of the first air channel.
[0006] Furthermore, the cross section of the through hole is elliptical.
[0007] Furthermore, the inner wall of the through hole is provided with a spiral guide plate, which guides the flow path of the air flowing through the through hole, thereby increasing the contact area between the air and the inner wall of the through hole and improving the heat dissipation effect.
[0008] Furthermore, the inner wall of the through hole is provided with a plurality of inner recesses at intervals along its length direction, so that the air flowing through the through hole stays briefly at the inner recesses and contacts with the inner recesses with a larger area, thereby improving the heat dissipation effect.
[0009] Furthermore, the mounting base includes a first base and a second base; the first base is connected to one end of the clamp in the length direction; the second base is connected to one end of the clamp in the width direction and is arranged away from the core.
[0010] The transformer can be installed horizontally through the first base, and the transformer can be installed vertically through the second base, which is flexible.
[0011] Furthermore, the dry-type transformer also includes a high-voltage tap; the high-voltage tap is arranged on the outside of the high-voltage winding.
[0012] Furthermore, the dry-type transformer also includes a low-voltage interface busbar, and the low-voltage interface busbar is connected to the low-voltage winding.
[0013] Furthermore, the dry-type transformer also includes a high-voltage interface busbar, and the high-voltage interface busbar is connected to the high-voltage winding.
[0014] Furthermore, the high-voltage winding and the low-voltage winding are both epoxy resin cast integrally molded structures.
[0015] The beneficial effect of the utility model is as follows: by setting a first air duct between the high-voltage winding and the low-voltage winding, and setting a honeycomb-briquette-shaped second air duct arranged circumferentially along the first air duct on the low-voltage winding and / or the high-voltage winding, the first air duct and the second air duct are used to achieve efficient heat dissipation of the high-voltage winding and the low-voltage winding, thereby improving the heat dissipation capacity of the transformer, and the second air duct is in the shape of honeycomb-briquette, which improves heat dissipation while ensuring the structural strength of the high and low voltage windings. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Figure 1 This is a schematic diagram of the main structure of the medium and high frequency epoxy resin cast dry-type transformer of the utility model.
[0017] Figure 2 for Figure 1 Right view of .
[0018] Figure 3 for Figure 2 Schematic diagram of the cross-sectional structure.
[0019] Figure 4 Schematic diagram of Litz wire welding.
[0020] In the figure, 1-iron core; 2-high voltage winding; 3-low voltage winding; 4-high voltage tapping piece; 5-low voltage interface busbar; 6-high voltage interface busbar; 7-first base; 8-second base; 9-silicone rod; 10-external terminal; 11-T-type copper terminal; 12-Litz wire; 13-clamp; 14-first air duct; 15-second air duct. DETAILED DESCRIPTION
[0021] The following is combined with Figures 1 to 4 The utility model is further described in detail with specific embodiments.
[0022] like Figure 1 , Figure 2 , Figure 3 The medium-high frequency epoxy resin cast dry-type transformer shown includes an iron core 1, a high-voltage winding 2, a low-voltage winding 3, a clamp 13, a mounting base, a high-voltage tapping piece 4, a low-voltage interface busbar 5, and a high-voltage interface busbar 6. In some embodiments, the high-voltage winding 2 and the low-voltage winding 3 are both epoxy resin cast integrated structures.
[0023] The transformer is a single-phase transformer and the application frequency range is 1000-2000Hz system.
[0024] The iron core 1 of this embodiment is a single-phase double-column iron core 1, wherein the iron core 1 is preferably made of high magnetic permeability and low loss materials suitable for medium and high frequency environments. The material of the iron core 1 can be high magnetic permeability oriented silicon steel sheets, amorphous alloys, nanocrystalline and other magnetic permeable materials. The design should reasonably select the magnetic flux density design to effectively reduce the influence of high frequency on the loss performance of the iron core 1 and avoid excessive loss and noise of the iron core 1.
[0025] The transformer design fully considers the skin effect caused by higher frequencies. The foil conductor with appropriate thickness and the enameled wire with appropriate wire diameter should be selected during the design.
[0026] Both the high voltage winding 2 and the low voltage winding 3 are cast in epoxy resin to enhance the short circuit and earthquake resistance of the windings.
[0027] The high-voltage winding 2 is wound with Litz wire 12. The high-voltage winding 2 is a layered and segmented structure. The internal and external leads and the tapping leads are welded by a special process to lead out the external terminal 10. The final appearance of the external terminal 10 is a boss with an inclination. If it is an integrated casting structure with the high-voltage winding 2, it is made of a round copper rod and has a threaded hole inside.
[0028] The low voltage winding 3 is wound with a foil conductor or a multi-strand Litz wire 12, and the inner and outer leads are led out through a welded busbar. The low voltage winding 3 is surrounded by the outer periphery of the iron core 1, and the high voltage winding 2 is surrounded by the outer periphery of the low voltage winding 3, and a spacing is maintained between the high voltage winding 2 and the low voltage winding 3 to form a ring-shaped first air channel 14. The upper and lower circumferences of the first air channel 14 are evenly filled with a number of circular silicone rods 9 to ensure that the windings will not be relatively displaced, and to enhance the transformer's ability to resist vibration and short circuit during transportation and operation.
[0029] In this embodiment, a plurality of honeycomb-briquette-shaped second air ducts 15 are provided in the low-voltage winding 3. The second air duct 15 includes a plurality of through holes, and the plurality of through holes are arranged at intervals along the circumference of the first air duct 14. The cross-section of the through holes is elliptical and is evenly arranged along the circumference of the coil. The second air duct 15 has a high utilization rate, which greatly reduces the operating temperature rise of the coil, ensuring that the coil has extremely strong short-circuit and overload resistance after the overall casting.
[0030] The second air duct 15 and the low-voltage winding 3 are integrally cast, and a resin layer is cast between the through holes of the second air duct 15 , which ensures the mechanical strength of the low-voltage winding 3 while improving the heat dissipation capacity of the low-voltage winding 3 .
[0031] In order to improve the mechanical strength of the low voltage winding 3, a support is also provided inside the through hole of the low voltage winding 3, and the support is integrally cast with the low voltage winding 3. The support is a horizontally arranged support rod.
[0032] In order to improve the heat dissipation performance, in some embodiments, a spiral guide vane is provided on the inner wall of the through hole. The spiral guide vane is formed in advance with epoxy resin material, and is embedded in the mold when the low-voltage winding 3 or the high-voltage winding 2 is cast in the mold. The spiral guide vane is a spiral wing structure, which is spaced apart from the center of the through hole, so that part of the airflow entering the through hole passes directly along the axial direction, while the other part of the airflow entering the through hole rises in a spiral in the through hole along the spiral guide vane, taking away the heat from the inner wall of the through hole in the process, thereby improving the heat dissipation effect.
[0033] In some embodiments, the inner wall of the through hole is provided with a plurality of inner recesses at intervals along its length direction. The inner recesses can be integrally formed during the winding casting process. Since the coil in the winding is closer to the inner recesses, heat can be transferred to the through hole through the inner recesses more quickly, thereby improving the heat dissipation effect.
[0034] The mounting base includes a first base 7 and a second base 8; the first base 7 is connected to one end of the length direction of the clamp 13; the second base 8 is connected to one end of the width direction of the clamp 13, and is arranged with its back to the core 1. The length direction of the first base 7 is perpendicular to the length direction of the clamp 13. The installation method of the transformer selects different mounting base configurations according to different requirements. The mounting base is equipped with mounting holes for customers to dock and install with the foundation. The second base 8 is selected when the transformer is installed vertically, and the first base 7 is selected when it is installed horizontally. When the transformer is installed vertically, the transformer can be cooled by self-cooling or forced air cooling. When the transformer is installed horizontally, the transformer should be cooled by forced air cooling.
[0035] The high and low voltage side interfaces of the transformer are led out by high voltage interface busbar 6 and low voltage interface busbar 5. Both high voltage interface busbar 6 and low voltage interface busbar 5 are tin-plated high conductivity hard busbars. The interfaces are equipped with mounting holes to ensure the interface overlap requirements.
[0036] The transformer as a whole adopts high-strength fastener bolts to ensure the overall vibration resistance requirements of the transformer.
[0037] like Figure 4 As shown, the welding process of the Litz wire 12 uses a soldering process to lead out the external terminal 10, which includes the following operating steps and specific requirements:
[0038] The paint film of Litz wire 12 needs to be stripped by tin melting furnace. Before stripping, the Litz wire 12 should be spread as much as possible to completely strip the paint. According to the different wire diameters, the stripping temperature should be set to 350-450℃. Before stripping, rosin can be applied on the surface of Litz wire 12 to make the stripping more complete. The stripping length of Litz wire 12 is recommended to be greater than 30mm to ensure sufficient contact area with T-type copper terminal 11. Use silver welding rods to solder the external terminal 10 and T-type copper terminal 11. The T-type copper terminal 11 should fully consider the contact area requirements with the external terminal 10 and Litz wire 12. Use electric iron and other auxiliary tools to arrange the wires, and try to keep them as close as possible; dip a layer of tin on the surface of the arranged Litz wire 12 and crimp it with the T-shaped copper terminal 11 using a tool; use an electric iron to heat or a hot air gun to heat the T-shaped copper terminal 11 from a distance, and add tin wire to the defective part to ensure that the joint between the Litz wire 12 and the T-shaped copper terminal 11 is filled with roundness and fullness; cool the welding position and grind the burrs with fine sandpaper; the welding position should be wrapped with insulation for reinforcement; the Litz wire 12 is composed of multiple strands of small-diameter round enameled wire twisted together, and the shape is generally rectangular, and the formed Litz wire 12 is wrapped with insulating material.
[0039] The utility model is applied to medium and high frequency dry-type transformers. Litz wire 12 is applied to reduce the influence of skin effect. A special welding process is adopted to lead out external terminals. It can be applied to 1000-2000Hz frequency. The overall structural strength is good, the performance is excellent, and the cost is low. The epoxy resin casting structure is adopted to enhance the transformer's anti-vibration and anti-short-circuit capabilities. The volume is reduced by about 1 / 10 compared with the original VPI structure.
[0040] The above are only preferred implementations of the utility model. The protection scope of the utility model is not limited to the above embodiments. All technical solutions under the idea of the utility model belong to the protection scope of the utility model. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the utility model should also be regarded as the protection scope of the utility model.
Claims
1. A medium and high frequency epoxy resin cast dry-type transformer, characterized in that: It includes an iron core, a high-voltage winding, a low-voltage winding, a clamp and a mounting base; the low-voltage winding is surrounded by the outer periphery of the iron core; the high-voltage winding is surrounded by the outer periphery of the low-voltage winding, and a distance is maintained between the high-voltage winding and the low-voltage winding to form a first annular air duct; a plurality of silicone rods are arranged at intervals along the circumferential direction in the first air duct, and the silicone rods are supported between the high-voltage winding and the low-voltage winding; a honeycomb-like second air duct arranged circumferentially along the first air duct is provided on the low-voltage winding and / or the high-voltage winding; the clamp is clamped at both ends of the iron core, and the mounting base is connected to the clamp.
2. A medium-high frequency epoxy resin cast dry-type transformer according to claim 1, characterized in that: The second air passage includes a plurality of through holes, and the plurality of through holes are arranged at intervals along the circumference of the first air passage.
3. A medium-high frequency epoxy resin cast dry-type transformer according to claim 2, characterized in that: The cross section of the through hole is elliptical.
4. A medium-high frequency epoxy resin cast dry-type transformer according to claim 2, characterized in that: The inner wall of the through hole is provided with a spiral guide plate.
5. A medium-high frequency epoxy resin cast dry-type transformer according to claim 2, characterized in that: The inner wall of the through hole is provided with a plurality of inner recesses at intervals along the length direction thereof.
6. A medium-high frequency epoxy resin cast dry-type transformer according to claim 1, characterized in that: The mounting base includes a first base and a second base; the first base is connected to one end of the clamp in the length direction; the second base is connected to one end of the clamp in the width direction and is arranged facing away from the iron core.
7. A medium-high frequency epoxy resin cast dry-type transformer according to claim 1, characterized in that: The dry-type transformer also includes a high-voltage tapping piece; the high-voltage tapping piece is arranged on the outside of the high-voltage winding.
8. A medium-high frequency epoxy resin cast dry-type transformer according to claim 1, characterized in that: The dry-type transformer also includes a low-voltage interface busbar, which is connected to the low-voltage winding.
9. A medium-high frequency epoxy resin cast dry-type transformer according to claim 1, characterized in that: The dry-type transformer also includes a high-voltage interface busbar, which is connected to the high-voltage winding.
10. A medium-high frequency epoxy resin cast dry-type transformer according to claim 1, characterized in that: The high-voltage winding and the low-voltage winding are both epoxy resin cast integrally molded structures.