Method for manufacturing a transformer core and transformer

Abstract

The embodiment of the application provides a transformer core preparation method and a transformer. The method comprises the following steps: providing a rectangular winding frame; rotating the rectangular winding frame around its axis, and continuously winding a strip around the circumferential direction of the rectangular winding frame to form a rectangular single-frame core on the outer periphery of the rectangular winding frame; and performing annealing treatment on the rectangular single-frame core. The rectangular winding frame comprises a first rectangular frame, a connecting portion, and a second rectangular frame. The first rectangular frame is provided with a first through hole penetrating through the frame body of the first rectangular frame. The connecting portion is connected to one side of the first through hole and connected with the first rectangular frame. The second rectangular frame is connected with the first rectangular frame through the connecting portion. The second rectangular frame is provided with a second through hole penetrating through the frame body of the second rectangular frame. The second through hole is in communication with the first through hole, and the area of the second through hole is smaller than the area of the first through hole. In the embodiment, the strip is directly wound along a rectangular path to form a shape, a subsequent extrusion shaping process is omitted, the overall steps are simple, and the overall production efficiency can be improved.

Description

Technical Field

[0001] This application belongs to the field of transformer technology, and particularly relates to a method for preparing a transformer core and a transformer. Background Technology

[0002] In existing technologies, some transformers require rectangular cores. Currently, most manufacturers in the industry use amorphous alloy strip winding for core production, which requires a "two-step forming" process. The specific process is as follows: first, the amorphous alloy strip is wound into a circular core blank to ensure that the strip layers are tightly bonded. Then, the circular blank is placed in a special rectangular mold, and the circular core is shaped into a rectangular core of the required specifications through hydraulic extrusion and other methods. After extrusion, the edges and surfaces of the core need to be trimmed to remove stress and defects generated during the extrusion process.

[0003] However, the above preparation method requires two processes: circular winding and extrusion shaping. The process is relatively complex, which not only increases the number of production steps and equipment investment, but also extends the manufacturing cycle, making it difficult to meet the needs of high-efficiency mass production.

[0004] It should be noted that the above content is not necessarily prior art, nor is it intended to limit the scope of patent protection of this application. Summary of the Invention

[0005] This application provides a method for preparing a transformer core and a transformer, in order to solve or alleviate one or more technical problems in the prior art.

[0006] The first aspect of this application provides a method for preparing a transformer core, comprising:

[0007] Provides a rectangular winding frame;

[0008] The rectangular winding frame is rotated about its axis, and strip is continuously wound around the circumference of the rectangular winding frame to form a rectangular single-frame iron core on the outer periphery of the rectangular winding frame.

[0009] The rectangular single-frame iron core is subjected to annealing treatment;

[0010] The rectangular winding frame includes a first rectangular frame, a connecting part, and a second rectangular frame.

[0011] The first rectangular frame has a first through-hole that penetrates its frame. The connecting part is connected to one side of the first through-hole and connected to the first rectangular frame. The second rectangular frame is connected to the first rectangular frame through the connecting part. The second rectangular frame has a second through-hole that penetrates its frame. The second through-hole and the first through-hole are connected. The area of ​​the second through-hole is smaller than the area of ​​the first through-hole.

[0012] Optionally, the method further includes:

[0013] Three annealed rectangular single-frame iron cores are sequentially spliced ​​together along the circumference to form an iron core assembly. The two ends of each rectangular single-frame iron core are attached to the corresponding ends of the adjacent rectangular single-frame iron core, so that the three rectangular single-frame iron cores are enclosed along the circumference to form a triangular prism iron core assembly.

[0014] Optionally, a reinforcing plate is attached to the inner wall of the rectangular winding frame.

[0015] Optionally, the strip is an iron-based amorphous strip.

[0016] Optionally, rotating the rectangular winding frame about its axis and continuously winding the strip in the circumferential direction of the rectangular winding frame includes:

[0017] Arrange the four strips on the winding path;

[0018] Simultaneously, four strips are attached and wound along the outer periphery of the rectangular winding frame, so that when the rectangular winding frame completes one revolution, the four strips are stacked to form four strip layers.

[0019] Optionally, the annealing process for the rectangular single-frame iron core includes:

[0020] Heating stage: The rectangular single-frame iron core is heated to 30℃~220℃ and held for 190min;

[0021] Temperature drawing stage: The rectangular single-frame iron core is heated to 160℃~330℃ and held for 352 minutes;

[0022] Reheating stage: The rectangular single-frame iron core is heated to 290℃~330℃ and held for 234 minutes;

[0023] Insulation stage: The rectangular single-frame iron core is kept at 330℃~335℃ for 210 minutes.

[0024] A second aspect of this application provides a transformer comprising a rectangular single-frame core prepared by any of the methods described above.

[0025] Optionally, the transformer includes a core assembly, which is formed by sequentially splicing together three rectangular single-frame cores along the circumference.

[0026] Each rectangular single-frame iron core has its two ends attached to the corresponding ends of the adjacent rectangular single-frame iron core, so that the three rectangular single-frame iron cores are enclosed circumferentially to form a triangular prism iron core assembly.

[0027] Optionally, the transformer further includes a mounting frame, which is sleeved on the outside of the core assembly;

[0028] The mounting frame includes an upper frame and a lower frame, which are fixedly connected by multiple tie rods.

[0029] The embodiments of this application employing the above-described technical solution may have the following advantages:

[0030] In this embodiment, the strip is directly wound along a rectangular path, eliminating the need for subsequent extrusion and shaping processes. Furthermore, this embodiment divides the three-dimensional wound core cross-section into two separate structures. Since the three-dimensional wound core is assembled from three single frames, each frame's core weight is 1 / 3 of the overall core. By separating the cross-section of each single frame and keeping the individual overall weight of each component below 1 t, the impact of the self-weight of the large-capacity amorphous alloy material on the process coefficient can be significantly reduced. The process coefficient of the large-capacity amorphous alloy closed-loop three-dimensional wound core is significantly reduced by approximately 15% to 35%, and the core no-load loss is correspondingly reduced by 15% to 35%. Assuming it is divided into two parts, keeping the core weight of each part below 1 t, the total core weight can reach 1 t multiplied by 2 multiplied by 3 equals 6 t, and so on. This structure is suitable for large amorphous alloy closed-loop three-dimensional wound cores and can significantly reduce the core's no-load loss.

[0031] The above overview is for illustrative purposes only and is not intended to be limiting in any way. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features of this application will become readily apparent from the accompanying drawings and the following detailed description. Attached Figure Description

[0032] In the accompanying drawings, unless otherwise specified, the same reference numerals throughout the various drawings denote the same or similar parts or elements. These drawings are not necessarily drawn to scale. It should be understood that these drawings depict only some embodiments disclosed in this application and should not be construed as limiting the scope of this application.

[0033] Figure 1 The flowchart illustrating a method for preparing a transformer core according to an embodiment of this application is shown in the schematic diagram.

[0034] Figure 2 This illustration schematically shows a rectangular winding frame structure in the method for preparing a transformer core according to an embodiment of this application;

[0035] Figure 3 The illustration schematically shows a multi-section cross-sectional view of a transformer core according to an embodiment of this application;

[0036] Figure 4 This is a schematic diagram of a transformer provided in an embodiment of this application.

[0037] Explanation of reference numerals in the attached figures:

[0038] 10 Rectangular single-frame iron core; 20 Mounting frame; 30 Tie rod; 31 Central tie rod assembly; 40 Pressing nail; 91 First frame; 92 Second frame; 93 Connecting part. Detailed Implementation

[0039] The embodiments of this application are described in detail below, examples of which are illustrated in the accompanying drawings. In the drawings, for clarity, the dimensions of layers, regions, elements, and their relative dimensions may be exaggerated. The same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0040] It should be understood that when an element or layer is referred to as "on," "adjacent to," "connected to," or "coupled to" other elements or layers, it may be directly on, adjacent to, connected to, or coupled to other elements or layers, or there may be intervening elements or layers. Conversely, when an element is referred to as "directly on," "directly adjacent to," "directly connected to," or "directly coupled to" other elements or layers, there are no intervening elements or layers. It should be understood that although the terms first, second, third, etc., may be used to describe various elements, components, areas, layers, and / or portions, these elements, components, areas, layers, and / or portions should not be limited by these terms. These terms are only used to distinguish one element, component, area, layer, or portion from another element, component, area, layer, or portion. Therefore, without departing from the teachings of this application, the first element, component, area, layer, or portion discussed below may be referred to as a second element, component, area, layer, or portion. And the discussion of a second element, component, area, layer, or portion does not imply that the first element, component, area, layer, or portion necessarily exists in this application.

[0041] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0042] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such terms can be used interchangeably where appropriate so that the embodiments of this application described herein can be implemented, for example, in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0043] In this application, when numerical intervals (i.e., numerical ranges) are involved, unless otherwise specified, the distribution of selectable numerical values ​​within the numerical interval is considered continuous, and includes the two endpoints of the numerical interval (i.e., the minimum and maximum values), as well as every numerical value between these two endpoints. Unless otherwise specified, when a numerical interval refers only to integers within that numerical interval, it includes the two endpoint integers of the numerical range, as well as every integer between the two endpoints, which is equivalent to directly listing every integer. When multiple numerical ranges are provided to describe features or characteristics, these numerical ranges can be merged. In other words, unless otherwise specified, the numerical ranges disclosed in this application should be understood to include any and all subranges included therein. The "numerical value" in the numerical interval can be any quantitative value, such as a number, percentage, ratio, etc. The term "numerical interval" can be broadly included to include percentage intervals, ratio intervals, proportion intervals, etc.

[0044] This application provides a method for manufacturing a transformer core and a transformer. This aims to alleviate the problems of complex manufacturing processes and low production efficiency in rectangular core fabrication. Details are provided below.

[0045] Exemplary embodiments according to this application will now be described in more detail with reference to the accompanying drawings. It should be understood that these exemplary embodiments may be implemented in many different forms and should not be construed as being limited to the embodiments set forth herein.

[0046] Please see Figure 1 This application provides a method for preparing a transformer core, comprising the following steps:

[0047] Step S100: Provide a rectangular winding frame.

[0048] The rectangular winding frame is used to define the strip winding path and forming dimensions, and its outer contour matches the inner contour of the target rectangular single-frame iron core. The rectangular winding frame can be an integral structure or a combined structure formed by connecting multiple frame segments, facilitating the removal or subsequent processing of the iron core after winding. In an optional embodiment, the rectangular winding frame includes a first rectangular frame and a second rectangular frame connected to each other, which are fixedly connected by a connecting part and integrally mounted on a rotating shaft to allow rotation around the axis. The dimensions of the rectangular winding frame can be replaced or adjusted according to the specifications of the target iron core.

[0049] Step S102: Rotate the rectangular winding frame around its axis and continuously wind strip in the circumference of the rectangular winding frame to form a rectangular single-frame core on the outer periphery of the rectangular winding frame.

[0050] The rectangular winding frame is driven by a drive mechanism to rotate continuously around its axis. Simultaneously, the strip is wound along the outer periphery of the rectangular winding frame under the action of a tension control device, thereby stacking layers to form a rectangular single-frame iron core. Unlike the existing method of first winding into a circle and then extruding and shaping, in this embodiment, the strip is directly wound along the rectangular path, eliminating the need for subsequent extrusion and shaping processes.

[0051] Step S104: Anneal the rectangular single-frame iron core.

[0052] Annealing is used to eliminate internal stress generated during winding and improve the magnetic properties of the core. The annealing process can be performed in a protective atmosphere or vacuum environment and includes sequentially executed stages of heating, temperature transition regulation, and holding, allowing the rectangular single-frame core to reach a predetermined annealing temperature and be held for a predetermined time before cooling. In an optional embodiment, the rectangular single-frame core remains mounted on the rectangular winding frame or a dedicated annealing fixture during annealing to maintain its rectangular dimensions and prevent deformation during the annealing process. After annealing, a rectangular single-frame core with stable dimensions and magnetic properties is obtained.

[0053] Furthermore, in this embodiment, the method further includes:

[0054] Step S200: The three annealed rectangular single-frame iron cores are sequentially spliced ​​together along the circumference to form an iron core assembly. The two ends of each rectangular single-frame iron core are attached to the corresponding ends of the adjacent rectangular single-frame iron core, so that the three rectangular single-frame iron cores are joined together along the circumference to form a triangular prism iron core assembly.

[0055] Each rectangular single-frame iron core has two ends that face and fit against the corresponding ends of the adjacent rectangular single-frame iron core, thus forming a closed enclosure structure. The overall cross-section after splicing has a triangular outline, extending axially to form a triangular prism iron core assembly. The fitting ends can be the straight edge end face of the rectangular single-frame iron core or a machined mating end face to improve splicing positioning accuracy and contact stability.

[0056] The core capacity of this embodiment is 8000KVA, which is suitable for 35KV medium-voltage power distribution networks.

[0057] In this embodiment, the rectangular winding frame is formed by four side plates. Specifically, two opposite side plates of the rectangular winding frame are slightly curved outwards, while the other two opposite side plates can be straight. A reinforcing plate is attached to the inner wall of the rectangular winding frame.

[0058] The side plates are slightly bent outwards, so that the outer periphery of the rectangular winding frame forms an outwardly convex arc profile, thereby reducing the stress concentration between the strip and the edge of the side plates during the strip winding process, reducing the bending stress of the strip and facilitating the strip bonding and forming.

[0059] In this embodiment, as Figure 2 As shown, the rectangular winding frame includes a first rectangular frame 91, a connecting part 93, and a second rectangular frame 92.

[0060] The first rectangular frame 91 has a first through-hole that penetrates its frame. The connecting part 93 is connected to one side of the first through-hole and connected to the first rectangular frame 91. The second rectangular frame 92 is connected to the first rectangular frame 91 through the connecting part 93. The second rectangular frame 92 has a second through-hole that penetrates its frame. The second through-hole is connected to the first through-hole. The area of ​​the second through-hole is smaller than the area of ​​the first through-hole.

[0061] Existing amorphous alloy three-dimensional wound cores employ a trapezoidal multi-segment cross-section structure, composed of multiple trapezoidal segments combined to form a single circular cross-section. Each trapezoidal segment is wound segment by segment using a winding machine. Due to the increased no-load loss caused by stress on the amorphous alloy material, the larger the capacity, the greater the impact of the core's weight on the overall no-load loss. According to measured data, the no-load loss process coefficient k is below 1.3 for cores weighing less than 0.8 tons, reaches 1.35 for a core weighing 1.5 tons, reaches 1.6 for a core weighing 3 tons, and exceeds 1.85 for a core weighing 8 tons. Therefore, significantly reducing the core process coefficient is a major challenge in reducing no-load loss for large-capacity closed-type amorphous alloy cores.

[0062] This embodiment divides the integral cross-section of the three-dimensional wound core into two separate structures. Since the three-dimensional wound core is assembled from three single frames, and the weight of each single frame is 1 / 3 of the total core weight, separating the cross-section of each single frame and keeping the weight of each individual component below 1 t can significantly reduce the impact of the self-weight of the large-capacity amorphous alloy material on the process coefficient. The process coefficient of the large-capacity amorphous alloy closed three-dimensional wound core is significantly reduced by about 15% to 35%, and the core no-load loss is correspondingly reduced by 15% to 35%. Assuming it is divided into two parts and the weight of each part is kept below 1 t, the total weight of the core can reach 1 t multiplied by 2 multiplied by 3 equals 6 t, and so on. This structure is suitable for large amorphous alloy closed three-dimensional wound cores and can significantly reduce the core no-load loss.

[0063] Understandable, such as Figure 3 As shown, the core cross-section of this embodiment is completely different from the conventional design. The existing technology in China uses a trapezoidal multi-segment cross-section structure for the amorphous alloy three-dimensional rolled core, which is composed of multiple trapezoidal segments combined into an integral circular cross-section. Because the amorphous alloy material experiences increased no-load loss and other key parameters under stress, the larger the capacity, the greater the impact of the core's self-weight on the overall no-load loss. According to current domestic measured data, the no-load loss process coefficient k is below 1.3 for cores weighing less than 0.8 tons, reaches 1.35 for cores weighing 1.5 tons, reaches 1.6 for cores weighing 3 tons, and exceeds 1.85 for cores weighing 8 tons. The core cross-section of this embodiment consists of two parts, and the dividing line position can be selected according to the total weight of the core. When the total weight of the core is less than 3 tons, the internal section is perpendicularly broken from the point of tangency with the diameter at a 60° angle to the center of the circle within the fifth segment of the core, dividing the core cross-section into two parts: an internal section of 4 segments and an external section of 7 segments, with the lower part supported by a frame. When the total weight of the core exceeds 3t, the core is vertically cut off from the point where the diameter is tangent to the center of the circle at a 60° angle within the 6th section of the core. The core section is divided into two parts: 5 sections inside and 7 sections outside. The lower part is supported by a skeleton (rectangular winding frame).

[0064] Furthermore, the internal support structure of the iron core in this embodiment is completely different. The rectangular winding frame in this embodiment adopts a double rectangular stepped structure and a split winding method. On the basis of the double rectangular stepped structure skeleton, it is wound in two parts, and an insulating support plate is added between the two parts for isolation.

[0065] This embodiment changes the core cross-section, skeleton, and winding method. When the total weight of the core is 1.5~3t, the core no-load loss process coefficient can be reduced from 1.6 to below 1.4. When the core weight is 3t~10t, the core process coefficient can be reduced from 1.8 to below 1.5.

[0066] The unique design of this embodiment significantly reduces the no-load loss of large-capacity amorphous alloy closed-loop three-dimensional wound cores. Furthermore, under the same standard requirements, the magnetic flux density can be appropriately increased and the number of turns reduced during design, thereby reducing the amount of core and copper used and lowering transformer costs.

[0067] In this embodiment, the strip is an iron-based amorphous strip, which is purchased from a manufacturer.

[0068] Specifically, this embodiment uses a non-crystalline alloy strip (NLTE) with low-loss, high-permeability, and a thickness of <0.026mm, and a unit loss of <0.06W / kg. A three-dimensional core is formed by integrally winding a single-frame square skeleton, and a vertical heat preservation annealing process is applied to the strip surface to achieve a completely symmetrical, equal-length, and shortest three-phase magnetic circuit. This reduces the no-load loss to 1.8769kW by nearly 60% compared to the national standard level 1 energy efficiency of 4.3kW, and by nearly 80% compared to the traditional silicon steel transformer of 7.87kW. At the same time, the magnetic flux density is optimized (1.4T), and a 2-3mm soft silicone coating process is used to effectively suppress the magnetostrictive effect, achieving a balance between energy saving, environmental protection, and quiet operation.

[0069] Furthermore, the embodiments of this application employ a three-dimensional wound core structure with no seams between core layers. The three-phase magnetic circuits are of equal and shortest length, and the magnetic circuit distribution is uniform, effectively reducing iron loss and no-load loss by 0.5 times, improving heat dissipation and increasing overload characteristics by 10%-20%. Simultaneously, the suspended core design, with its axial gravity forming a strong axial pre-tightening system for the coils, significantly enhances the coils' ability to withstand enormous axial electrodynamic forces and improves operational reliability during sudden short circuits, increasing the safety margin of axial short-circuit withstand capability by over 50%. Additionally, the use of concentric and conjugate high- and low-voltage disc-shaped coil continuous winding technology replaces the traditional separate winding and assembly process, reducing production time by approximately 25%. This achieves absolute geometric concentricity and electromagnetic conjugation between the high- and low-voltage coils and the core column, resulting in a highly axially symmetrical and radially uniform magnetic field distribution. This effectively eliminates circulating current and localized overheating hazards, improving operational efficiency and stability by an absolute value of 0.2% to 0.5%.

[0070] In addition, this application embodiment also constructs a multi-dimensional transformer body stabilization system based on redundant design. The internal system adopts a three-dimensional spatial grid positioning and constraint system. High-strength insulating laminates form a "grid" positioning in key parts, providing rigid support for core components without dead angles and ensuring structural stability under extreme conditions such as transportation and short circuits. The external clamps adopt a high-density redundant fastening matrix (multiple high-strength tie rods), which increases the number of fastening points by more than 60% compared to the traditional method and has a reasonable layout, forming a uniform pre-tightening force network. This network works in conjunction with the internal constraint system to provide the transformer with dual protection against long-term stress relaxation, vibration, and sudden mechanical stress, thereby greatly improving mechanical reliability.

[0071] The embodiments of this application also adopt a collaborative design of the main and longitudinal insulation structures. The main insulation structure adopts a thin paper tube and small oil gap scheme. By dividing the electric field with multiple insulating paper tubes, the insulation strength utilization rate is improved by 25%, and the insulation safety margin is improved by 30%. The longitudinal insulation structure is optimized in conjunction with corner rings, insulating partitions and other molded parts to achieve electric field homogenization in areas with concentrated electric fields, such as the winding ends. Finally, a robust and durable 35kV insulation system is constructed, which can stably withstand the combined stresses of electricity, heat and machinery.

[0072] In the method for preparing a transformer core according to an embodiment of this application, the step of rotating the rectangular winding frame around its axis and continuously winding the strip in the circumferential direction of the rectangular winding frame (step S102) may include:

[0073] Step S300: Arrange the four strips on the winding path.

[0074] Specifically, the four strips can be arranged in an overlapping manner along the winding path and wound synchronously, forming four layers of strip after a single turn. A winding device with four feeding rollers can be used to wind the four amorphous alloy strips onto their respective feeding rollers. In one embodiment, the axis connecting the four feeding rollers forms a rectangle, and the strips wound on the four feeding rollers form a certain angle with each other, ultimately converging on the rectangular winding frame.

[0075] Step S302: Simultaneously wrap the four strips along the outer periphery of the rectangular winding frame, so that when the rectangular winding frame completes one revolution, the four strips are stacked to form four strip layers.

[0076] The four feeding rollers are synchronously linked and controlled to match the conveying speed of the four strips with the rotation speed of the rectangular winding frame, thereby maintaining consistent strip tension during the winding process and synchronously adhering to the outer circumferential surface of the rectangular winding frame. As the rectangular winding frame continues to rotate, the four strips are synchronously superimposed on the same loop, so that each loop of winding simultaneously forms four strip layers, which are accumulated loop by loop to form a rectangular core blank.

[0077] By simultaneously winding four strips in parallel, multi-layer stacking can be achieved in a single winding process. Compared to single-strip or double-strip winding methods, a higher number of layers in the core structure can be obtained with the same number of rotations, thereby shortening the winding time and improving forming efficiency. At the same time, simultaneous feeding from multiple feed shafts helps reduce the stress on a single strip, improves conveying stability, reduces strip wrinkles or interlayer loosening, and makes the interlayer bonding of the wound rectangular core more compact.

[0078] Furthermore, since the strip is directly formed into the target rectangular structure by winding it around the outer perimeter of the rectangular frame, there is no need to first wind it into a circular blank and then shape it with a mold. This eliminates intermediate shaping and trimming processes, reduces processing steps and time costs, and reduces the adverse effects of shaping stress on the strip structure and magnetic properties. Thus, production efficiency is improved while ensuring the consistency of core quality.

[0079] In an optional embodiment, the annealing process of the rectangular single-frame core includes:

[0080] Heating stage: The rectangular single-frame iron core is heated to 30℃~220℃ and held for 190 minutes.

[0081] Temperature drawing stage: The rectangular single-frame iron core is heated to 160℃~330℃ and held for 352 minutes.

[0082] Reheating stage: The rectangular single-frame iron core is heated to 290℃~330℃ and held for 234 minutes.

[0083] Insulation stage: The rectangular single-frame iron core is kept at 330℃~335℃ for 210 minutes, and the final furnace exit temperature is 335℃~337℃.

[0084] This application also provides a transformer, including a rectangular single-frame core 10 prepared by the method for preparing transformer cores as described in any of the above embodiments. For details, please refer to [the relevant documentation / reference]. Figure 4 .

[0085] In an optional embodiment, the transformer includes a core assembly formed by sequentially splicing together three rectangular single-frame cores 10 along the circumference.

[0086] Specifically, three rectangular single-frame iron cores 10 can be arranged sequentially end to end in the circumferential direction. Each rectangular single-frame iron core 10 constitutes a side structure of the iron core assembly, and the magnetic circuit continuity is achieved by end docking between adjacent single-frame iron cores. By using multiple single-frame iron cores spliced ​​together to form an integral iron core assembly, the difficulty of integral winding or integral assembly of an integral closed iron core can be avoided, improving the manufacturing and installation flexibility of the iron core assembly, while also facilitating transportation, replacement, and maintenance.

[0087] In this design, the two ends of each rectangular single-frame iron core 10 are fitted with the corresponding ends of the adjacent rectangular single-frame iron core 10, so that the three rectangular single-frame iron cores 10 are circumferentially enclosed to form a triangular prism iron core assembly. The end-fitting surfaces of the adjacent rectangular single-frame iron cores 10 can be straight end faces after winding and shaping or mating end faces after trimming. After the three are enclosed, a closed magnetic circuit structure with a triangular cross-section is formed, i.e., a triangular prism iron core assembly. This structure can be used for three-phase transformer iron core configurations, so that the three-phase magnetic flux is closed in the three rectangular single-frame iron cores 10 respectively, with good magnetic circuit symmetry and low leakage flux. Since each rectangular single-frame iron core 10 is formed by winding continuous strip material, its end-layer continuity is good, and the increase in magnetic reluctance after splicing is small, which is conducive to maintaining the low loss and high magnetic permeability characteristics of the overall iron core assembly. Furthermore, compared with the integral triangular iron core, the triangular prism splicing structure is easier to achieve modular manufacturing and assembly, and can reduce the processing and transportation difficulty of large-size iron cores.

[0088] In this embodiment, the transformer further includes a mounting frame 20, which is sleeved on the outside of the core assembly; the mounting frame 20 includes an upper frame and a lower frame, which are fixedly connected by multiple tie rods 30.

[0089] The mounting frame 20 also includes a central tie rod assembly 31, which includes an upper limit part, a lower limit part, and a central tie rod. The upper limit part abuts against the top of the plurality of coils, the lower limit part abuts against the bottom of the plurality of coils, and the two ends of the central tie rod are respectively fixed between the upper limit part and the lower limit part. The central tie rod is located between the three coils.

[0090] Preferably, in this embodiment, the upper frame and the lower frame are fixedly connected by 13 tie rods, including 12 outer edge tie rods 30 and a single central tie rod. That is, the external clamps adopt a high-density redundant fastening matrix (13 high-strength tie rods), which increases the number of fastening points by more than 60% compared with the traditional method and has a reasonable layout, forming a uniform pre-tightening force network. This network works in conjunction with the internal constraint system to provide the transformer with dual protection against long-term stress relaxation, vibration and sudden mechanical stress, thereby greatly improving mechanical reliability.

[0091] In this embodiment, a coil is wound on the part of each pair of adjacent rectangular single-frame iron cores 10 that are in contact with each other. A pressure pin 40 is installed on the top of the mounting frame 20. The pressure pin 40 passes through the top of the upper frame and is connected to the top of the coil. Since the iron core is installed inside the mounting frame 20, the iron core exerts a downward gravity on the mounting frame 20 due to its own weight. The mounting frame 20 then transmits the pressure to the coil through the pressure pin 40, thereby providing a downward pressure on the coil and improving the short-circuit withstand capability.

[0092] Using pressure pins 40 can increase the axial clamping force of the coil, fix the coil, prevent displacement during operation, and improve the short-circuit withstand capability (the coil will move upward as a whole during a short circuit, and the short-circuit withstand capability is improved by preventing the coil from moving upward); the iron core is suspended and its own weight presses down on the coil, thereby improving the short-circuit withstand capability.

[0093] It should be noted that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential," etc., are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. The directional terms "inner" and "outer" refer to the inside or outside relative to the outline of the component itself. For example, if a device in the drawings is inverted, a device described as "above" or "on top of" other devices or structures will subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein are interpreted accordingly.

[0094] It should also be noted that the terms "one embodiment," "another embodiment," and "embodiment" used in this application refer to specific features, structures, or characteristics described in connection with that embodiment, which are included in at least one embodiment described in the general description of this application. The appearance of the same expression in multiple places in the specification does not necessarily refer to the same embodiment. Furthermore, when a specific feature, structure, or characteristic is described in connection with any embodiment, the intention is to suggest that implementing such a feature, structure, or characteristic in conjunction with other embodiments also falls within the scope of this application.

[0095] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0096] It should also be noted that the above are merely preferred embodiments of this application and do not limit the scope of patent protection of this application. Any equivalent structural or procedural changes made using the content of this application’s specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the scope of patent protection of this application.

Claims

1. A method for preparing a transformer core, characterized in that, include: Provides a rectangular winding frame; The rectangular winding frame is rotated about its axis, and strip is continuously wound around the circumference of the rectangular winding frame to form a rectangular single-frame iron core on the outer periphery of the rectangular winding frame. The rectangular single-frame iron core is subjected to annealing treatment; The rectangular winding frame includes a first rectangular frame, a connecting part, and a second rectangular frame. The first rectangular frame has a first through-hole that penetrates its frame. The connecting part is connected to one side of the first through-hole and connected to the first rectangular frame. The second rectangular frame is connected to the first rectangular frame through the connecting part. The second rectangular frame has a second through-hole that penetrates its frame. The second through-hole and the first through-hole are connected. The area of ​​the second through-hole is smaller than the area of ​​the first through-hole. The step of rotating the rectangular winding frame about its axis and continuously winding the strip around the circumference of the rectangular winding frame includes: Arrange the four strips on the winding path; Simultaneously, four strips are attached and wound along the outer periphery of the rectangular winding frame, so that when the rectangular winding frame completes one rotation, the four strips are stacked to form four strip layers. The annealing process for the rectangular single-frame iron core includes: Heating stage: The rectangular single-frame iron core is heated to 30℃~220℃ and held for 190min; Temperature drawing stage: The rectangular single-frame iron core is heated to 160℃~330℃ and held for 352 minutes; Reheating stage: The rectangular single-frame iron core is heated to 290℃~330℃ and held for 234 minutes; Insulation stage: The rectangular single-frame iron core is kept at 330℃~335℃ for 210 minutes.

2. The method for preparing a transformer core according to claim 1, characterized in that, The method further includes: Three annealed rectangular single-frame iron cores are sequentially spliced ​​together along the circumference to form an iron core assembly. The two ends of each rectangular single-frame iron core are attached to the corresponding ends of the adjacent rectangular single-frame iron core, so that the three rectangular single-frame iron cores are enclosed along the circumference to form a triangular prism iron core assembly.

3. The method for preparing a transformer core according to claim 1, characterized in that, The inner wall of the rectangular winding frame is fitted with a reinforcing plate.

4. The method for preparing a transformer core according to claim 1, characterized in that, The strip is an iron-based amorphous strip.

5. A transformer, characterized in that, Including a rectangular single-frame iron core prepared by the method described in any one of claims 1 to 4.

6. The transformer according to claim 5, characterized in that, The transformer includes a core assembly, which is formed by three rectangular single-frame cores sequentially spliced ​​together along the circumference. Each rectangular single-frame iron core has its two ends attached to the corresponding ends of the adjacent rectangular single-frame iron core, so that the three rectangular single-frame iron cores are enclosed circumferentially to form a triangular prism iron core assembly.

7. The transformer according to claim 6, characterized in that, The transformer also includes a mounting frame, which is sleeved on the outside of the core assembly; The mounting frame includes an upper frame and a lower frame, which are fixedly connected by multiple tie rods.

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