Three-phase roll iron core of distribution transformer

Abstract

The utility model relates to the technical field of transformer manufacturing, in particular to a three-phase roll iron core of a distribution transformer, which comprises three iron core monomers with the same structure, each iron core monomer comprises an upper iron yoke and a lower iron yoke which are opposite up and down, and a left core column and a right core column which are opposite left and right; wherein each iron core single body is connected with the other two iron core single bodies through the left core column and the right core column of the iron core single body respectively, the connecting sides of any two connected iron core single bodies are provided with connecting surfaces which are in continuous contact, and the connecting surface of each iron core single body is tangent to the adjacent surface. According to the utility model, the connecting surface between any two connected iron core monomers is limited, and the phenomenon of local concentration or distortion of magnetic flux at the joint can be reduced through fillet transition between the connecting surface and the adjacent surface of the adjacent iron core monomers; and the connecting surfaces are arc surfaces, so that the problem that the contact area is relatively reduced due to the fact that the connecting surfaces are tangent to the adjacent surfaces is solved.

Description

Technical Field

[0001] The utility model relates to the technical field of transformer manufacturing, in particular to a three-phase wound core of a distribution transformer. Background Art

[0002] The three-phase wound core structure is a core structure for distribution transformers. Unlike traditional laminated cores, it utilizes thin silicon steel sheets cut into a specific shape and then continuously wound into a closed three-phase core column. This winding method results in a core cross-section that approximates a circular or rectangular shape, more closely resembling the ideal shape. Three-phase wound core distribution transformers offer advantages such as low losses, low noise, high mechanical strength, and excellent heat dissipation. These transformers meet energy-saving and environmental requirements and are gaining increasing adoption in power distribution systems.

[0003] In the prior art, the contact area between the connecting surfaces of two adjacent single-phase wound cores is required to be as large as possible. This reduces magnetic resistance, eddy current losses and hysteresis losses in the core, and improves transformer efficiency. A larger contact area also helps improve the core's mechanical stability and enhance its short-circuit resistance. However, the connection between two single-phase wound cores in the prior art is often designed to form a sharp angle, which can easily cause localized magnetic flux concentration or distortion at the connection.

[0004] Therefore, the prior art urgently needs a three-phase wound core structure that can ensure that the contact area of ​​the connection surface is as large as possible while reducing the local concentration or distortion of the magnetic flux at the connection. Utility Model Content

[0005] Some simplifications or omissions may be made in this section and the abstract of the specification and the title of the utility model of this application to avoid blurring the purpose of this section, the abstract of the specification and the title of the utility model, and such simplifications or omissions shall not be used to limit the scope of the utility model.

[0006] In order to solve the deficiencies of the prior art, one object of the present invention is to provide a three-phase wound core for a distribution transformer.

[0007] In order to achieve the above objectives, the present invention adopts the following technical solutions: a three-phase wound core of a distribution transformer, comprising:

[0008] Three iron core monomers with the same structure, each of the iron core monomers includes an upper iron yoke and a lower iron yoke opposite to each other, and a left core column and a right core column opposite to each other;

[0009] Each of the core monomers is connected to the other two core monomers through its left core column and its right core column, and the connecting sides of any two connected core monomers have a continuous contact connection surface and two rounded surfaces adjacent to the connection surface.

[0010] As a preferred solution of the three-phase wound core of the distribution transformer of the present invention, the area of ​​the connecting surface is S1, the sum of the areas of the two rounded surfaces is S2, wherein:

[0011] S1 / (S1+S2)≥67%.

[0012] As a preferred solution of the three-phase wound core of the distribution transformer of the present invention, the connection surface is a plane, and the connection surfaces of the left core and the right core of the same core unit are symmetrically distributed.

[0013] As a preferred solution of the three-phase wound core of the distribution transformer of the present invention, the connection surface is an arc surface, and the connection surfaces of the left core leg and the right core leg located in the same core unit are adapted to each other.

[0014] As a preferred solution for the three-phase wound core of the distribution transformer described in the utility model, the connection surfaces of the left core column and the right core column located in the same core unit are respectively convex and concave structures, and the two connection surfaces of the convex and concave structures coincide with each other.

[0015] As a preferred solution of the three-phase wound core of the distribution transformer of the utility model, wherein: the projections of the connecting surface and the two adjacent rounded surfaces on the cross section are respectively an arc-shaped connecting segment and two arc segments;

[0016] Wherein, the chord length of the connecting segment is L1, and the arc length of the connecting segment is L2, then: (L2-L1) / L1≥33%.

[0017] As a preferred solution of the three-phase wound core of the distribution transformer of the present invention, any one of the connecting surfaces has only an outwardly convex arc shape or only an inwardly concave arc shape.

[0018] As a preferred solution of the three-phase wound core of the distribution transformer of the present invention, wherein: the connecting section includes an outer convex portion and an inner concave portion, and the outer convex portion and the inner concave portion have a common tangent line D at the connection;

[0019] The outer convex portion of the left core column in the same iron core unit is matched with the inner concave portion of the right core column, and the inner concave portion of the left core column in the same iron core unit is matched with the outer convex portion of the right core column.

[0020] As a preferred solution of the three-phase wound core of the distribution transformer of the present invention, wherein: the maximum distance from the chord of the connecting section to the arc length of the connecting section is M, then M / L1≤10% is satisfied.

[0021] As a preferred solution of the three-phase wound core of the distribution transformer of the present invention, the connection surfaces of any two connected core units are glued.

[0022] The three-phase wound core of a distribution transformer of the present invention has the following beneficial effects: the present invention limits the connection surface between any two connected core monomers, and can reduce the local concentration or distortion of magnetic flux at the connection by transitioning between the connection surface and the adjacent surface of adjacent core monomers through rounded corners; and by setting the connection surface as an arc surface, it compensates for the problem of relatively reduced contact area caused by the tangency of the connection surface and the adjacent surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0024] Figure 1 It is a schematic diagram of the overall three-phase wound core structure of the distribution transformer of the utility model.

[0025] Figure 2 This is a schematic diagram of the overall top view of the three-phase wound core of the distribution transformer of the present invention.

[0026] Figure 3 The figure is a schematic diagram of the three-phase structure of a single iron core of a distribution transformer of the present invention.

[0027] Figure 4 This is a front structural schematic diagram of a single core unit of a three-phase wound core of a distribution transformer of the present invention.

[0028] Figure 5 The figure is a top view cross-sectional structural diagram of a single core unit of a three-phase wound core of a distribution transformer of the present invention.

[0029] Figure 6 This is a schematic top view of the cross-sectional result of the planar connection surface shown in Example 1 of the present invention.

[0030] Figure 7 This is a schematic top view cross-sectional result of one of the implementation methods of the arc-shaped connection surface shown in Example 2 of the present invention.

[0031] Figure 8 This is a schematic top view cross-sectional result of another embodiment of the arc-shaped connecting surface shown in Example 2 of the present invention.

[0032] In the figure: 100, upper iron yoke; 200, lower iron yoke; 300, left core column; 400, right core column; 500, connecting surface; 501, connecting section; 501a, outer convex part; 501b, inner concave part; 600, rounded surface; 601, arc segment. DETAILED DESCRIPTION

[0033] In order to make the objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below with reference to the accompanying drawings.

[0034] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0035] Secondly, the term "one embodiment" or "embodiment" herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in various places throughout this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0036] Example 1

[0037] Reference Figures 1-6 , which is the first embodiment of the utility model, provides a three-phase wound core of a distribution transformer, which can reduce the local concentration or distortion of magnetic flux at the connection point. It includes three core monomers with the same structure, each core monomer includes a core column and a yoke, the yoke is an upper iron yoke 100 and a lower iron yoke 200 opposite to each other, and the core columns are a left core column 300 and a right core column 400 opposite to each other. The core monomers are formed by tightly winding silicon steel sheets along a specific direction to form a closed magnetic circuit. The three core monomers are arranged in an equilateral triangle. The core columns are used to connect the windings, and the connection between the core columns and the iron yoke is an arc transition.

[0038] Specifically, each core unit is connected to the other two core units through its left core column 300 and its right core column 400. The connecting sides of any two connected core units have a continuous contact connection surface 500, and the connection surface 500 of each core unit is tangent to the adjacent surface. Usually, the adjacent surface of the connection surface 500 can be set as a rounded surface 600 in the form of chamfered corners, so as to ensure that the connection surface 500 and the rounded surface 600 are tangent at the connection point; the connection surfaces 500 of any two connected core units are bonded by adhesive glass glue to ensure that the contact area of ​​the connection surface 500 does not change. Figure 2 、 4As shown in Figures 5 and 6, the connecting surface 500 of adjacent core monomers and the adjacent surfaces are also transitioned through fillets, which can reduce the local concentration or distortion of magnetic flux at the connection.

[0039] Furthermore, the area of ​​the connecting surface 500 is denoted as S1, and the sum of the areas of the adjacent surfaces tangent to the connecting surface 500 is denoted as S2, where: S1 / (S1+S2)≥67%. Since setting the connecting surface 500 and its two adjacent surfaces to be tangent will result in a reduction in the contact area of ​​the connecting surface 500 relative to the original, in order to maintain the basic contact area, it is necessary to limit the area ratio of the connecting surface 500 and its tangent surfaces, thereby reducing the local concentration or distortion of magnetic flux at the connection point while meeting the basic contact area requirements. By setting up an experiment, while adjusting the contact area of ​​the connecting surface 500, the performance parameters of the transformer are measured, and the relationship between the area ratio of the connecting surface 500 and its tangent surfaces is obtained.

[0040] First, the test object can be selected as a three-phase wound core transformer of the same model and the same manufacturing process, ensuring that other conditions except the contact area are the same; second, the contact area can be adjusted by adding insulating gaskets of different thicknesses between the connection surfaces 500 of two adjacent core units, so that the contact area is reduced from 100% to 50%; then, using professional power testing instruments (such as a comprehensive transformer tester), the transformer performance parameters of each contact area interval of 1% are measured, and the average data of each contact area section is measured.

[0041] Based on the analysis of the average change patterns of multiple sets of key parameters measured in practice, when the contact area decreases from 100% to 50%, the no-load current increases by at least 10%, and the no-load loss increases by at least 20%. For the no-load current, as the contact area decreases, the total magnetic resistance of the magnetic circuit increases. To maintain the same operating magnetic flux (at rated voltage), the no-load current increases linearly. When the contact area is reduced to 50%, the no-load current increases by 10%. For the no-load loss, the loss consists of two parts: a fixed part and a part inversely proportional to the contact area. Therefore, as the contact area decreases, the loss increases. When the contact area is reduced to 50%, the loss increases by 20%.

[0042] Next, determine the minimum contact area. Based on actual application requirements, we typically require that the transformer's no-load losses and no-load current not exceed standard limits. For example, if the standard no-load losses do not exceed 1100W (a 10% increase compared to 100% contact area), the contact area must be at least 66.67%. If the standard no-load current does not exceed 0.53% (a 6% increase), the contact area must be at least 62.5%. In practice, losses may be more of a concern, so a minimum contact area of ​​approximately 67% (rounded off) is recommended.

[0043] In summary: as the contact area of ​​the connection surface of two adjacent single-phase wound cores decreases from 100% to 50%, the no-load current and no-load loss gradually increase. In order to meet basic performance, the contact area should be maintained at at least 67%.

[0044] The connection surfaces 500 can be planes, and the connection surfaces 500 of the left and right core legs 300 and 400 of the same core unit are symmetrically distributed. Planar connection surfaces 500 ensure consistent contact surfaces. The symmetrical distribution of the two connection surfaces 500 allows the three core units of identical structure to form an equilateral triangle, which helps improve the mechanical stability of the core.

[0045] Example 2

[0046] Reference Figure 1-Figure 7 , which is the second embodiment of the present utility model. Different from the previous embodiment, the connecting surface 500 of this embodiment is set as an arc surface, which solves the problem of relatively reduced contact area caused by the tangency between the connecting surface 500 and the adjacent surface.

[0047] Specifically, the connection surface 500 is a curved surface, and the connection surfaces 500 of the left core leg 300 and the right core leg 400 of the same core unit are mutually adapted. When the distance between two adjacent surfaces of the connection surface 500 is the same, the curved surface has a larger area than the flat surface, which can further compensate for the contact area loss caused by tangency with the adjacent surface. At the same time, to ensure that the connection surfaces 500 between adjacent core units continue to match, the connection surfaces 500 of the left core leg 300 and the right core leg 400 of the same core unit are configured to be mutually adapted, so that the connection surfaces 500 of the three core units with the same structure can fully contact each other.

[0048] Furthermore, the connecting surfaces 500 of the left core 300 and the right core 400 within the same core unit are convex and concave, respectively, and the convex and concave connecting surfaces 500 conform to each other. In this embodiment, the cross-sectional projections of the connecting surface 500 and its two adjacent rounded surfaces 600 are arc-shaped connecting segments 501 and two arc segments 601, respectively. The arc surface of the connecting surface 500 can increase the contact area of ​​the connecting surface 500 to a certain extent through the cooperation of the outer convexity and the inner concaveness. Compared with the planar connection, it can fit more tightly, reduce the air gap, thereby reducing the magnetic resistance, improving the magnetic conductivity of the magnetic circuit, and reducing the no-load loss; and during installation, the arc surface cooperation is easier to find the fitting position, and due to its own geometric shape, it can better maintain the fitting state when subjected to force, reduce the poor fitting caused by external force or vibration, and enhance the reliability of the connection; in addition, this cooperation method can make the magnetic flux more evenly distributed at the connection, avoid local concentration and distortion of the magnetic flux at the corners of the planar connection, thereby reducing the eddy current loss and hysteresis loss in the iron core, and improving the efficiency and performance of the transformer; and the arc surface can better disperse stress when subjected to force, reduce the problem of excessive local stress, thereby improving the mechanical strength and short-circuit resistance of the iron core, and extending the service life of the transformer.

[0049] Because the connecting surface 500 and its two adjacent rounded surfaces 600 are respectively swept by the arc-shaped connecting segment 501 and the two arc segments 601, the area relationship between the connecting surface 500 and the adjacent surfaces is the same as the length relationship between the connecting segment 501 and the two arc segments 601. Here, denoting the chord length of the connecting segment 501 as L1 and the arc length of the connecting segment 501 as L2, the following condition is satisfied: L2 - L1 / L1 ≥ 33%. In Example 1, the minimum contact area is limited to 67%. Therefore, to compensate for the sufficient contact area, the arc surface preferably has a contact area 33% greater than the flat surface.

[0050] like Figure 7 As shown, in one embodiment, any connecting surface 500 has only an outward convex arc shape or only an inward concave arc shape, which is relatively convenient for processing, but it is easy to make the structural differences between the left core column 300 and the right core column 400 of the same core unit too large.

[0051] Example 3

[0052] Reference Figures 1-6 、 Figure 8 , which is the third embodiment of the present utility model. Different from the previous embodiment, the connecting section 501 of this embodiment includes an outer protrusion 501a and an inner recess 501b.

[0053] Specifically, such as Figure 8As shown, in this embodiment, the connecting section 501 includes an outer protrusion 501a and an inner recess 501b, and the outer protrusion 501a and the inner recess 501b have a common tangent D at the connection, that is, the two are transitioned through a continuous smooth curve, and no sharp angle is generated at the connection; wherein, the outer protrusion 501a of the left core column 300 in the same core monomer is adapted to the inner recess 501b of the right core column 400, and the inner recess 501b of the left core column 300 in the same core monomer is adapted to the outer protrusion 501a of the right core column 400.

[0054] It should be understood that when two core units are connected, the outer protrusion 501a of one core unit must fit into the inner recess 501b of the other core unit. This way, both the left core 300 and the right core 400 of the same core unit have one outer protrusion 501a and one inner recess 501b, which significantly increases the manufacturing difficulty while also making the left core 300 and the right core 400 more similar in structure.

[0055] Preferably, the maximum distance from the chord of connecting segment 501 to the arc length of connecting segment 501 is denoted as M, and M / L1 ≤ 10%. By limiting the relationship between the distance M from the arc length to the farthest point on the chord length and the chord length L1, that is, limiting the curvature of connecting segment 501 to be gentle, the magnetic flux is more evenly distributed at connecting surface 500 while ensuring that the contact area of ​​the curved surface is 33% greater than that of the flat surface.

[0056] The rest of the structure is the same as that of Example 2.

[0057] It will be understood that in the development of any actual embodiment, as in any engineering or design project, numerous implementation-specific decisions may be made. Such a development effort may be complex and time-consuming, but for those of ordinary skill having the benefit of this disclosure, the development effort will be a routine task of design, fabrication, and production without undue experimentation.

[0058] 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 the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, and all of these should be included in the scope of the claims of the present invention.

Claims

1. A three-phase wound core of a distribution transformer, characterized in that: The invention comprises three iron core monomers with the same structure, each of the iron core monomers comprises an upper iron yoke (100) and a lower iron yoke (200) opposite to each other, and a left core column (300) and a right core column (400) opposite to each other; Each of the iron core monomers is connected to the other two iron core monomers through its left core column (300) and its right core column (400), and the connecting sides of any two connected iron core monomers have a continuously contacting connection surface (500) and two rounded corner surfaces (600) adjacent to the connection surface (500).

2. The three-phase wound core of the distribution transformer according to claim 1, characterized in that: The area of ​​the connecting surface (500) is S1, and the sum of the areas of the two rounded surfaces (600) is S2, wherein: S1 / (S1+S2)≥67%.

3. The three-phase wound core of the distribution transformer according to claim 1 or 2, characterized in that: The connection surface (500) is a plane, and the connection surfaces (500) of the left core column (300) and the right core column (400) of the same iron core unit are symmetrically distributed.

4. The three-phase wound core of the distribution transformer according to claim 1 or 2, characterized in that: The connection surface (500) is an arc surface, and the connection surfaces (500) of the left core column (300) and the right core column (400) located in the same iron core unit are adapted to each other.

5. The three-phase wound core of the distribution transformer according to claim 4, characterized in that: The connection surfaces (500) of the left core column (300) and the right core column (400) located in the same iron core unit are respectively convex and concave structures, and the two connection surfaces (500) of the convex and concave structures match each other.

6. The three-phase wound core of the distribution transformer according to claim 5, characterized in that: The projections of the connecting surface (500) and its two adjacent rounded surfaces (600) on the cross section are respectively an arc-shaped connecting segment (501) and two circular arc segments (601); Wherein, the chord length of the connecting section (501) is L1, and the arc length of the connecting section (501) is L2, and the following is satisfied: (L2-L1) / L1≥33%.

7. The three-phase wound core of the distribution transformer according to claim 6, characterized in that: Any of the connecting surfaces (500) has only an outwardly convex arc shape or only an inwardly concave arc shape.

8. The three-phase wound core of the distribution transformer according to claim 6, characterized in that: The connecting section (501) includes an outer convex portion (501a) and an inner concave portion (501b), and the outer convex portion (501a) and the inner concave portion (501b) have a common tangent line D at the connection point; The outer convex portion (501a) of the left core column (300) in the same iron core monomer is matched with the inner concave portion (501b) of the right core column (400), and the inner concave portion (501b) of the left core column (300) in the same iron core monomer is matched with the outer convex portion (501a) of the right core column (400).

9. The three-phase wound core of the distribution transformer according to claim 6, characterized in that: The maximum distance from the chord of the connecting segment (501) to the arc length of the connecting segment (501) is M, and M / L1≤10% is satisfied.

10. The three-phase wound core of the distribution transformer according to claim 4, characterized in that: The connection surfaces (500) of any two connected iron core units are glued.

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