Iron core for transformer

Abstract

The present invention relates to an iron core of a transformer in which no-load loss is low. The iron core of a transformer comprises core sub-parts in which a plurality of steel sheets are stacked and which include coupling holes that pass through in the stacking direction, wherein the number of the coupling holes is two or less. A plurality of the core subparts are disposed in a direction crossing the stacking direction.

Description

Transformer iron core

[0001] The present invention relates to a transformer core having low no-load loss.

[0002] A transformer is a device that uses electromagnetic induction to change alternating voltage and current, making it an essential component in electronic products. Transformers are manufactured by winding a magnetic core with an electrical conductor, a coil. Electrical steel, which has low magnetic loss, is used as the core. Cores can be either red or wound.

[0003] Key characteristics of transformers include loss and noise. In particular, no-load loss and no-load noise, which are power losses that occur instantaneously regardless of whether the transformer is operating, are regulated by law. Accordingly, various measures have been proposed to reduce no-load loss and no-load noise.

[0004] To reduce no-load loss, grain-oriented electrical steel, which boasts excellent iron loss, is used as the core. Because iron loss increases with increasing grain-oriented electrical steel thickness, the thinnest possible material can be selected. However, in the past, various technologies for reducing iron loss in electrical steel were developed, leading to the development of improved materials each year. However, beyond material-based approaches to reducing iron loss, technologies for reducing no-load loss in transformers are also needed.

[0005] According to one embodiment of the present invention, a transformer core with improved no-load loss can be provided. Furthermore, no-load loss can be minimized while maintaining conventional structural fastening methods suitable for mass production of transformers.

[0006] The objectives of the present invention are not limited to the above-described scope. Those skilled in the art will have no difficulty understanding the additional objectives of the present invention from the overall content of this specification.

[0007] A transformer core according to one embodiment of the present invention comprises a core sub-part in which a plurality of steel plates are laminated and have a coupling hole penetrating in the lamination direction, the number of the coupling holes being two or less, and a plurality of the core sub-parts are arranged in a direction intersecting the lamination direction.

[0008] In addition, the core sub-part is any one of a first yoke arranged parallel to a first direction intersecting the stacking direction, a second yoke arranged parallel to and spaced apart from the first yoke, a first leg arranged between the first yoke and the second yoke in a second direction intersecting the stacking direction and the first direction, a second leg arranged parallel to and spaced apart from the first leg, or a third leg arranged parallel to and spaced apart from the first leg and the second leg, and at least one of the plurality of core sub-parts may have 1 coupling hole.

[0009] Additionally, at least one of the first leg, the second leg, and the third leg may have one coupling hole.

[0010] Additionally, the number of the coupling holes included in the third leg may be 1.

[0011] In addition, a plurality of the core sub-parts are combined to form a closed cross-section, and a first length in a longitudinal direction intersecting the stacking direction is longer than a second length in a width direction intersecting the stacking direction and the longitudinal direction, and the position of the joining hole may be located at a position 0.45 to 0.70 times the second length based on an end close to the closed cross-section in the width direction, based on the second length.

[0012] Additionally, the position of the above-mentioned joining hole may be located at 0.55 to 0.60 times the second length.

[0013] In addition, one coupling hole is formed in the first yoke and the second yoke, and the first coupling hole formed in the first yoke and the second coupling hole formed in the second yoke may not be arranged in a straight line in the second direction.

[0014] Additionally, the position of the coupling hole included in the third leg may be located at the center of the third leg in the first direction and the second direction.

[0015] According to another embodiment of the present invention, a transformer core comprises a yoke portion including a first yoke in which a plurality of steel plates are laminated and arranged in parallel in a first direction intersecting the lamination direction of the steel plates, and a second yoke in which the first yoke is spaced apart from and arranged in parallel with the first yoke, and a leg portion including a first leg in which a plurality of steel plates are laminated and connected to the first yoke and the second yoke and arranged in a second direction intersecting the first direction, and a second leg in which the first leg is spaced apart from and arranged in parallel with the first leg, wherein the yoke portion and the leg portion form a closed rectangular cross-section in a coupled state, and a coupling hole is formed penetrating in the lamination direction in the yoke portion or the leg portion, and the number of coupling holes formed in each of the first yoke, the second yoke, the first leg, or the second leg may be 2 or less.

[0016] Additionally, the leg portion may include a third leg positioned parallel to the first leg and the second leg and within the closed rectangular cross-section, and one coupling hole may be formed at the center of the third leg in the first direction and the second direction.

[0017] According to the present invention, no-load loss and no-load noise are reduced, and the performance of the transformer is improved.

[0018] Figure 1 is a perspective view for explaining a transformer iron core.

[0019] Figures 2a to 2c illustrate the shapes of various iron cores, with Figure 2a illustrating a two-sided iron core, Figure 2b illustrating a three-sided iron core, and Figure 2c illustrating a five-sided iron core.

[0020] FIGS. 3A to 3D are perspective views illustrating embodiments of the present invention, wherein FIG. 3A illustrates a first embodiment, FIG. 3B illustrates a second embodiment, FIG. 3C illustrates a third embodiment, and FIG. 3D illustrates a fourth embodiment.

[0021] Figures 4a to 4c are drawings for explaining the position of the coupling hole. Figure 4a shows a case where the coupling hole is formed in the center, Figure 4b shows a case where the coupling hole is formed close to the outer end, and Figure 4c shows a case where the coupling hole is formed close to the inner end.

[0022] Figures 5a to 5c are perspective views showing comparative examples, where Figure 5a shows comparative example 6, Figure 5b shows comparative example 7, and Figure 5c shows comparative example 8.

[0023] Hereinafter, preferred embodiments of the present invention will be described with reference to the attached drawings. However, the embodiments of the present invention may be modified in various other forms, and the scope of the present invention is not limited to the embodiments described below.

[0024] In addition, the embodiments of the present invention are provided to more completely explain the present invention to a person having average knowledge in the relevant technical field.

[0025] The shape and size of elements in the drawing may be exaggerated for clearer explanation.

[0026] In describing the embodiments of the present invention, if a detailed description of a known technology related to the present invention is judged to unnecessarily obscure the gist of the present invention, such detailed description will be omitted. In addition, the terms described below are terms defined in consideration of their functions in the present invention, and these may vary depending on the intention or custom of the user or operator. Therefore, the definitions should be made based on the contents throughout this specification. The terminology used in the detailed description is only for the purpose of describing the embodiments of the present invention and should in no way be limiting. Unless clearly defined otherwise, expressions in the singular form include plural meanings.

[0027] In this description, expressions such as "including" or "having" are intended to indicate certain features, numbers, steps, operations, elements, portions or combinations thereof, and should not be construed to exclude the presence or possibility of one or more other features, numbers, steps, operations, elements, portions or combinations thereof other than those described.

[0028] Unless otherwise specified in the specification of the present invention, the % unit means weight %.

[0029] In this specification, terms such as 'top', 'upper part', 'top surface', 'bottom', 'lower part', 'bottom', 'side', etc. are based on the drawings, and in reality, they may vary depending on the direction in which the elements or components are arranged.

[0030] Additionally, throughout the specification, when we say that a part is 'connected' to another part, this includes not only cases where it is 'directly connected', but also cases where it is 'indirectly connected' with other elements in between.

[0031] Below, the present invention will be described in detail through each embodiment or example of the present invention. It should be noted that each embodiment or example described in this specification is not limited to a single embodiment or example, but may be combined with other embodiments or examples. Therefore, the citation of a claim in the patent claims is only an example of an embodiment, and the technical concept of the present invention should not be interpreted solely as a combination with the cited claim, and combinations with various claims also fall within the scope of the technical concept of the present invention.

[0032] Hereinafter, the present invention will be described in detail through examples. However, it should be noted that the examples described below are intended only to illustrate and concretize the present invention and are not intended to limit the scope of the invention. This is because the scope of the invention is determined by the matters set forth in the patent claims and matters reasonably inferred therefrom.

[0033] Hereinafter, in the drawing, a first direction (DR1), a second direction (DR2) intersecting the first direction (DR1), and a third direction (DR3) intersecting the first direction (DR1) and the second direction (DR2) and the direction of lamination of the steel plates are shown.

[0034] Figure 1 is a perspective view for explaining a transformer iron core.

[0035] The primary coil of a transformer is connected to the input circuit where the voltage is to be changed, and the secondary coil is connected to the output circuit where the changed voltage is used. Here, magnetic energy is used to convert electrical energy between the primary and secondary coils.

[0036] Depending on whether a power load is connected to the secondary coil, the characteristics are divided into no-load and loaded characteristics. The no-load characteristic occurs when there is no load and is constant regardless of whether the transformer is operating. The power loss consumed in the core is called no-load loss.

[0037] To reduce no-load loss, electrical steel (S), which has low iron loss, can be used as the core. Because iron loss increases with increasing thickness, it's advisable to select the thinnest possible electrical steel (S). Furthermore, because iron loss decreases with increasing content of high-resistivity elements like silicon and aluminum, it's advisable to select electrical steel (S) with high resistivity characteristics.

[0038] For example, a transformer core having excellent no-load characteristics can be manufactured by laminating single sheets of grain-oriented electrical steel (S) having a thickness of 0.05 mm to 5.0 mm. For example, the steel sheet (S) can be grain-oriented electrical steel (S) and can have a thickness of 0.05 mm to 5.0 mm depending on the type of transformer.

[0039] According to one embodiment of the present invention, a transformer core can be formed by combining a plurality of core sub-parts (100, 200, 300, 400, 500) formed by stacking a plurality of steel plates (S).

[0040] The core sub-part (100, 200, 300, 400, 500) may be one of the first yoke (100), the second yoke (200), the first leg (300), the second leg (400), and the third leg (500). In addition, a plurality of core sub-parts (100, 200, 300, 400, 500) may be combined to form a transformer core.

[0041] Even if the core is manufactured with a constant weight using the same electrical steel sheet (S), the no-load characteristics of the transformer vary. This is because they can vary depending on the shape of the core sub-part (100, 200, 300, 400, 500) of the core.

[0042] The first yoke (100) is a steel plate laminate assembly arranged parallel to the first direction (DR1). The second yoke (200) is a steel plate laminate assembly arranged parallel to the first yoke (100) and spaced apart from it. The first leg (300) is a steel plate laminate assembly arranged parallel to the first yoke (100) and spaced apart from it. The second leg (400) is a steel plate laminate assembly arranged parallel to the first leg (300). The third leg (500) is a steel plate laminate assembly arranged parallel to the first leg (300) and the second leg (400). The core sub-part (100, 200, 300, 400, 500) can be any one of the first yoke (100), the second yoke (200), the first leg (300), the second leg (400), and the third leg (500), and a plurality of core sub-parts (100, 200, 300, 400, 500) can be arranged in the first direction (DR1) or the second direction (DR2) intersecting the stacking direction (DR3) to form a transformer core.

[0043] For example, a plurality of core sub-parts (100, 200, 300, 400, 500) are arranged in a first direction (DR1) or a second direction (DR2) that intersects the stacking direction (DR3), and the plurality of core sub-parts (100, 200, 300, 400, 500) can form a closed rectangular cross-section based on a surface formed by the first direction (DR1) and the second direction (DR2) in a combined state.

[0044] For example, the no-load characteristics of the iron core may vary depending on the width and length of the first yoke (100) and the second yoke (200), the size of the first leg (300) and the second leg (400), or the height of the stacking direction (DR3) of the core sub-parts (100, 200, 300, 400, 500), and thus management of these points may be required.

[0045] According to one embodiment of the present invention, a transformer core may include a yoke portion (100, 200) and a leg portion (300, 400, 500).

[0046] The yoke section (100, 200) may include a first yoke (100) in which a plurality of steel plates (S) are laminated and arranged parallel to a first direction (DR1) intersecting with the lamination direction (DR3) of the steel plates (S), and a second yoke (200) arranged parallel to and spaced apart from the first yoke (100).

[0047] The leg portion (300, 400, 500) may include a first leg (300) in which a plurality of steel plates (S) are laminated and connected to the first yoke (100) and the second yoke (200) and arranged in the second direction (DR2), and a second leg (400) arranged parallel to and spaced apart from the first leg (300). In addition, the leg portion (300, 400, 500) may include a third leg (500) positioned parallel to the first leg (300) and the second leg (400) and within a closed rectangular cross-section.

[0048] For example, a joint (610, 620, 630, 640, 650, 660) connecting core sub-parts (100, 200, 300, 400, 500) may be formed. For example, the joints (610, 620, 630, 640, 650, 660) may be laminated in a step-lap manner, and according to the step-lap manner, the iron loss that increases rapidly in the joints (610, 620, 630, 640, 650, 660) may be minimized. However, the joints (610, 620, 630, 640, 650, 660) are not limited to being formed in a step-lap manner.

[0049] Figures 2a to 2c illustrate various shapes of iron cores, with Figure 2a illustrating a two-sided iron core, Figure 2b illustrating a three-sided iron core, and Figure 2c illustrating a five-sided iron core.

[0050] As shown in Fig. 2a, the third leg (500) may not be included, and the first yoke (100), the second yoke (200), the first leg (300), and the second leg (400) may be arranged to form a closed rectangular cross-section. As an example, this is also called a two-angle iron core.

[0051] In the case where one third leg (500) is included as in Fig. 2b, the third leg (500) may be positioned between the first leg (300) and the second leg (400). The third leg (500) may be positioned at a midpoint between the first leg (300) and the second leg (400). For example, it is also called a triangular core.

[0052] For example, there may be multiple third legs (501, 502, 503). Referring to FIG. 2c, it can be seen that three third legs (500) are formed. The third leg (500) is positioned between the first leg (300) and the second leg (400), but the multiple third legs (501, 502, 503) may be positioned spaced apart from each other. For example, it is also called a pentagonal core. The number of third legs (500) may vary depending on the design specifications required for the transformer core, and is not limited to the case where there is one third leg (500), as in FIG. 2b. Hereinafter, the case where there is one third leg (500) will be described.

[0053] Figures 3a to 3d illustrate transformer cores according to the first to fourth embodiments of the present invention.

[0054] According to one embodiment of the present invention, the core sub-part (100, 200, 300, 400, 500) of the transformer core includes a coupling hole penetrating in the stacking direction (DR3), and the number of coupling holes may be 2 or less.

[0055] When multiple core sub-parts (100, 200, 300, 400, 500) of a transformer core are joined in a step lap, the lamination may be difficult. To facilitate this, a long rod may be erected before lamination and fitted into the joining holes formed in the individual steel plates (S). When the steel plates (S) forming the first yoke (100) or the second yoke (200) and the first leg (300), the second leg (400), or the third leg (500) are connected in a step lap and laminated, the core sub-parts (100, 200, 300, 400, 500) may be joined to the joining holes of the steel plate laminate assembly using a joining member such as a bolt in order to maintain the laminated joining state. And the first and second winding cylinders are fitted into the erected second yoke (200) or first yoke (100) and the first leg (300), second leg (400) or third leg (500) as one, and the first yoke (100) or second yoke (200) is fitted into the first leg (300), second leg (400) or third leg (500) to manufacture the transformer core, so that assembly of the core can be facilitated, quality deviation can be reduced, and production speed can be greatly improved, so that it can be suitable for mass production. Accordingly, the joining hole in the core can act as a guide to facilitate core assembly. Alternatively, it can be used as a passage through which a joining member such as a bolt is joined to fix the core sub-part (100, 200, 300, 400, 500). However, the joining hole becomes a magnetic resistance that interferes with the flow of a magnetic field. If there are no coupling holes, assembly of the core stack is difficult, resulting in connection defects and a rapid increase in the transformer's no-load loss. To prevent the magnetic resistance from increasing and the no-load loss from rapidly increasing, the number of coupling holes formed in the core sub-parts (100, 200, 300, 400, 500) can be limited.

[0056] For example, the number of joining holes formed in the first yoke (100) may be two or less.

[0057] Referring to Fig. 3a, there are two coupling holes (H11d, H12d) formed in the first yoke (100) according to the first embodiment. Referring to Fig. 3b, there are two coupling holes (H11e, H12e) formed in the first yoke (100) according to the second embodiment. Referring to Fig. 3c, there is one coupling hole (H11f) formed in the first yoke (100) according to the third embodiment. Referring to Fig. 3d, there is one coupling hole (H12g) formed in the first yoke (100) according to the fourth embodiment.

[0058] For example, the number of joining holes formed in the second yoke (200) may be two or less.

[0059] Referring to Fig. 3a, there are two coupling holes (H21d, H22d) formed in the second yoke (200) according to the first embodiment. Referring to Fig. 3b, there are two coupling holes (H21e, H22e) formed in the second yoke (200) according to the second embodiment. Referring to Fig. 3c, there is one coupling hole (H22f) formed in the second yoke (200) according to the third embodiment. Referring to Fig. 3d, there is one coupling hole (H21g) formed in the second yoke (200) according to the fourth embodiment.

[0060] For example, the number of joining holes formed in the first leg (300) may be two or less.

[0061] Referring to Fig. 3a, there are two coupling holes (H31d, H32d) formed in the first leg (300) according to the first embodiment. Referring to Fig. 3b, there is one coupling hole (H31e) formed in the first leg (300) according to the second embodiment. Referring to Fig. 3c, there is one coupling hole (H31f) formed in the first leg (300) according to the third embodiment. Referring to Fig. 3d, there is one coupling hole (H31g) formed in the first leg (300) according to the fourth embodiment.

[0062] For example, the number of joining holes formed in the second leg (400) may be two or less.

[0063] Referring to Fig. 3a, there are two coupling holes (H41d, H42d) formed in the second leg (400) according to the first embodiment. Referring to Fig. 3b, there is one coupling hole (H41e) formed in the second leg (400) according to the second embodiment. Referring to Fig. 3c, there is one coupling hole (H41f) formed in the second leg (400) according to the third embodiment. Referring to Fig. 3d, there is one coupling hole (H41g) formed in the second leg (400) according to the fourth embodiment.

[0064] For example, the number of joining holes formed in the third leg (500) positioned within a closed rectangular cross-section parallel to the first leg (300) and the second leg (400) may be two or less.

[0065] Referring to Fig. 3a, there are two coupling holes (H51d, H52d) formed in the third leg (500) according to the first embodiment. Referring to Fig. 3b, there is one coupling hole (H51e) formed in the second leg (400) according to the second embodiment. Referring to Fig. 3c, there is one coupling hole (H51f) formed in the second leg (400) according to the third embodiment. Referring to Fig. 3d, there is one coupling hole (H51g) formed in the second leg (400) according to the fourth embodiment.

[0066] As described above, the number of coupling holes formed in each of the first yoke (100), the second yoke (200), the first leg (300) or the second leg (400) is formed to be two or less, thereby reducing the overall no-load loss and reducing the influence of magnetic resistance.

[0067] When the number of coupling holes in a core sub-part (100, 200, 300, 400, or 500) exceeds two, the magnetic field becomes a bottleneck due to the numerous magnetic reluctances, rapidly increasing the magnetic flux density and causing significant fluctuations. The unstable magnetic field flow causes severe harmonic waveforms, resulting in significantly poor core loss.

[0068] According to one embodiment of the present invention, at least one of the plurality of core sub-parts (100, 200, 300, 400, 500) may have the number of coupling holes as 1.

[0069] It may be more advantageous if the core sub-parts (100, 200, 300, 400, 500) have only one coupling hole. For example, at least one of the core sub-parts (100, 200, 300, 400, 500) included in the yoke portion (100, 200) or the core sub-parts (100, 200, 300, 400, 500) included in the leg portion (300, 400, 500) may have only one coupling hole. Since it is not necessary for all the included core sub-parts (100, 200, 300, 400, 500) to have two coupling holes, some core sub-parts (100, 200, 300, 400, 500) may have only one coupling hole. For example, one of the first leg (300), the second leg (400) included in the leg portion (300, 400, 500) or the first yoke (100), the second yoke (200) included in the yoke portion (100, 200) may be formed with one coupling hole, and the other may be formed with two coupling holes. For example, as in the second embodiment, one of the first yoke (100), the second yoke (200), the first leg (300), and the second leg (400) may be formed with one coupling hole, and the other may be formed with two coupling holes. Alternatively, one coupling hole may be formed in the first yoke (100) and the second yoke (200), and the first leg (300) and the second leg (400) may be formed with two coupling holes. Alternatively, the first leg (300) and the second leg (400) may be formed with one joining hole, and the first yoke (100) and the second yoke (200) may be formed with two joining holes. By forming one joining hole and eliminating the joining hole at the previously existing location, difficulties arising during manufacturing may be solved, such as by applying a joining solution to the joining portions (610, 620, 630, 640, 650, 660) and fixing them. The present invention is not limited to the method of joining the joining portions (610, 620, 630, 640, 650, 660). For example, the joining portions (610, 620, 630, 640, 650, 660) may be assembled using a step-lap method, and if the joining portions (610, 620, 630, 640, 650, 660) have 1.If a small gap of 5 mm or more occurs, the no-load loss of the transformer may rapidly increase. Therefore, it is possible to bond at the joint (610, 620, 630, 640, 650, 660) to minimize the gap caused by the step lap compared to other parts of the core. However, if bonding is done, it is not easy to disassemble the connection during reassembly due to a defect in the no-load loss of the transformer. Therefore, if bonding is not used at the joint (610, 620, 630, 640, 650, 660), at least one bonding hole is required, and the location of the bonding hole may be important for fixing the core structure.

[0070] For example, at least one of the first leg (300), the second leg (400), and the third leg (500) may have one coupling hole.

[0071] With reference to the second embodiment, the first leg (300), the second leg (400), and the third leg (500) can be joined by three or more core sub-parts (100, 200, 300, 400, 500) in the second direction (DR2), unlike the first yoke (100) and the second yoke (200) which are only fixed at the outer side. Therefore, the joining with the first yoke (100) and the second yoke (200) and the fixing by the other legs during manufacturing can be relatively easy. Accordingly, the number of joining holes (H31e, H41e, H51e) in at least one core sub-part (100, 200, 300, 400, 500) among the first leg (300), the second leg (400), and the third leg (500) can be 1.

[0072] For example, one coupling hole (H51e, H51f, H51g) may be formed in the third leg (500). In addition, the position of the coupling hole (H51e, H51f, H51g) included in the third leg (500) may be located at the center of the third leg (500) in the first direction (DR1) and the second direction (DR2).

[0073] Referring to FIGS. 3b, 3c and 3d, the third leg (500) of the second, third and fourth embodiments is positioned within a closed rectangular cross-section, unlike the first yoke (100), the second yoke (200), the first leg (300) and the second leg (400), so that the necessity of fixing the steel plate (S) and the manufacturing process is relatively small due to the combination with other core sub-parts (100, 200, 300, 400, 500). Accordingly, the third leg (500) may have only one coupling hole (H51e, H51f, H51g). And, for ease of fixation, one coupling hole (H51e, H51f, H51g) formed in the third leg (500) can be positioned at the center of the third leg (500) in the first direction (DR1) and the second direction (DR2).

[0074] According to one embodiment of the present invention, one coupling hole (H11f, H12g, H22f, H21g) is formed in the first yoke (100) and the second yoke (200), and the first coupling hole (H11f) formed in the first yoke (100) and the second coupling hole (H22f) formed in the second yoke (200) may not be arranged in a straight line in the second direction (DR2).

[0075] Referring to FIGS. 3c and 3d, the third and fourth embodiments may have one coupling hole (H11f, H12g, H22f, H21g) in each of the first yoke (100), the second yoke (200), the first leg (300), and the second leg (400). In particular, when one coupling hole (H11f, H12g, H22f, H21g) is formed in the first yoke (100) and the second yoke (200), one coupling hole located in the first yoke (100) may be defined as a first coupling hole (H11f, H12g), and one coupling hole located in the second yoke (200) may be defined as a second coupling hole (H22f, H21g). In the case where the first coupling hole (H12g) of the first yoke (100) and the second coupling hole (H21g) of the second yoke (200) are positioned in a straight line in the second direction (DR2) as in the fourth embodiment, as compared to the case where the first coupling hole (H11f) of the first yoke (100) and the second coupling hole (H22f) of the second yoke (200) are not positioned in a straight line in the second direction (DR2) as in the third embodiment, the assembly of the plurality of core sub-parts (100, 200, 300, 400, 500) is relatively difficult, and the probability of poor alignment may be somewhat higher in the fourth embodiment compared to the third embodiment. Accordingly, as in the third embodiment, one coupling hole (H11f, H22f) is formed in the first yoke (100) and the second yoke (200), and it may be relatively advantageous in the manufacturing process that the first coupling hole (H11f) formed in the first yoke (100) and the second coupling hole (H22f) formed in the second yoke (200) are not arranged in a straight line in the second direction (DR2).

[0076] Figure 4 is a drawing illustrating the positions of the coupling holes located in the core sub-part. (a) to (c) illustrate embodiments in which the positions of the coupling holes in the width direction are different. Among the multiple core sub-parts, the first leg is shown as an example, and the same can be applied to the first yoke, the second yoke, and the second leg.

[0077] For example, a plurality of the core sub-parts (100, 200, 300, 400, 500) are combined to form a closed cross-section, and a first length (not shown) in a longitudinal direction (DR1 or DR2) intersecting the stacking direction (DR3) is longer than a second length (w) which is a length in a width direction (DR2 or DR1) intersecting the stacking direction (DR3) and the longitudinal direction (DR1 or DR2), and the positions of the coupling holes (Ha, Hb, Hc) may be positioned at 0.45 to 0.70 times the second length (w) based on one end closer to the closed cross-section in the width direction (DR2 or DR1) with respect to the second length (w). More specifically, the positions of the coupling holes (Ha, Hb, Hc) may be positioned at 0.55 to 0.60 times the second length.

[0078] With reference to the first leg (300), the width direction may be the same as the first direction (DR1). One end closer to the closed cross-section may be shorter than the other end farther from the closed cross-section. Based on one end, the coupling hole (Ha) may be formed closer to the center as in (a) of Fig. 4, the coupling hole (Hb) may be formed closer to the other end as in (b) of Fig. 4, and the coupling hole (Hc) may be formed closer to one end as in (c) of Fig. 4. At this time, the positions of the coupling holes (Ha, Hb, Hc) in the first direction (DR1) may be defined as the first position (w_h1), the second position (w_h2), and the third position (w_h3). In addition, the position (w_h / w) of the coupling hole relative to the second length may be determined based on the position. When the coupling hole (Ha) is placed at the center in the width direction as shown in (a) of Fig. 4, the value of the position of the coupling hole relative to the second length (w_h1 / w) is 0.5. In addition, when the value of the position of the coupling hole relative to the second length (w_h2 / w) defined in (b) of Fig. 4 is compared with the value of the position of the coupling hole relative to the second length (w_h3 / w) defined in (c) of Fig. 4, the former is larger, and the width direction position of the coupling hole can be limited based on this criterion.

[0079] Since the magnetic field tends to flow mainly toward the corners and the side close to the closed cross-section, it tends to flow toward the area with low magnetic resistance along the path. This means that the magnetic flux density inside the iron core is high. If the value of the position of the coupling hole relative to the second length (w_h / w) is less than 0.45, a large magnetic resistance is formed by the coupling hole on the inside of the iron core where the magnetic flux density is highly distributed, resulting in high iron loss. On the other hand, if the position of the coupling hole relative to the second length (w_h / w) is formed at a point greater than 0.7, the area of ​​the other end in the width direction from the coupling hole becomes too narrow, which aggravates the bottleneck phenomenon of the magnetic field, and as a result, a very high magnetic flux density is formed, causing the magnetic field to flow unevenly overall, which aggravates the generation of harmonics and rapidly increases the iron loss. Therefore, to solve this problem, the position of the joining hole is preferably located at 0.45 to 0.70 times the second length based on the end close to the closed cross-section in the width direction, based on the second length. Furthermore, it can be located at 0.55 to 0.60 times the second length closer to the center.

[0080] And, in the case of the third leg (500), it is geographically located in the center in terms of the flow of the magnetic field. Therefore, when a three-phase AC power source is applied, the induced magnetic field may flow to the third leg (500) via the first leg (300), or the magnetic field may flow to the third leg (500) via the second leg (400), or the magnetic field may flow to the third leg (500) simultaneously from both directions. Ultimately, since the magnetic flux density is less likely to be biased toward one side in the width direction of the legs (300, 400, 500), and it is advantageous for the magnetic field to be uniformly distributed with a high magnetic flux density, it may be advantageous for the third leg (500) to have a coupling hole formed in the center in the width direction.

[0081] Table 1 below shows the results of an experiment on no-load loss according to the location of the coupling hole in the width direction. The power loss that occurs when the secondary winding is opened and the rated voltage is applied to the primary winding while the winding part is wound on the iron core is defined as the rated no-load loss, and the coupling hole (Ha) located at the center in the width direction is set as the standard ((when w_h / w=0.5)) and the no-load loss is expressed as a proportional value (%). The location of the coupling hole is applied only to the first yoke (100), the second yoke (200), the first leg (300), and the second leg (400), and the result was derived by making the location of the coupling hole of the third leg (500) located inside be located at the center.

[0082] Position of the coupling hole in the width direction (w_h / w) No-load loss at rated voltage (%) No-load loss at voltage exceeding 10% of rated voltage (%) Comparative example 10.2 104.2 106.3 Comparative example 20.4 102.2 103.9 Comparative example 30.4 3 100.3 100.7 Invention example 10.5 599.298.6 Invention example 20.6 599.799.3 Comparative example 40.7 2 100.2 100.6 Comparative example 50.8 100.9 101.6

[0083] In Comparative Examples 1 to 3, the inner side close to the closed side of the core sub-part (100, 200, 300, 400, 500) where the coupling hole is located is a section where the magnetic field is most concentrated and the magnetic flux density is much higher than other areas. In addition, even if the design magnetic flux density is low, the magnetic flux density at the corner of the core can easily reach the saturation section. This indicates that it is not desirable to place the coupling hole in a section where the magnetic flux density is high. In Inventive Examples 1 and 2, the coupling hole (Hb) was formed in a section that was deviated from the center in the width direction to the outer side. It can be seen that the no-load loss is somewhat improved because the coupling hole (Hb) is formed at a point where the magnetic flux density is closer to the outer side than the corner and inner side of the core. Comparative Examples 4 and 5 are cases where the coupling hole is formed close to the outer side of the core. The area between the outer surface of the core and the coupling hole becomes too narrow, which aggravates the bottleneck phenomenon of the magnetic field, resulting in the formation of a very high magnetic flux density, which causes the magnetic field to flow unevenly throughout, resulting in the generation of severe harmonics. This causes a rapid increase in iron loss. Therefore, the coupling hole (Ha, Hb) is positioned 0.45 to 0.70 times the second length (w) closer to the center in the width direction, and more advantageously, the position of the coupling hole (Hb) is positioned 0.55 to 0.60 times the second length (w) slightly closer to the outside based on the center in the width direction, which can more significantly reduce the no-load loss.

[0084] FIGS. 5A to 5C illustrate comparative examples, wherein FIG. 5A illustrates a case where more than two coupling holes are formed in all core sub-parts, FIG. 5B illustrates a case where more than two coupling holes are formed in core sub-parts corresponding to the first yoke and the second yoke, and FIG. 5C illustrates a case where more than two coupling holes are formed in core sub-parts corresponding to the first leg, the second leg, and the third leg.

[0085] Referring to FIG. 5a, Comparative Example 6 has four coupling holes (H11a, H12a, H13a, H14a) formed in the first yoke (100), four coupling holes (H21a, H22a, H23a, H24a) formed in the second yoke (200), three coupling holes (H31a, H32a, H33a) formed in the first leg (300), three coupling holes (H41a, H42a, H43a) formed in the second leg (400), and three coupling holes (H51a, H52a, H53a) formed in the third leg (500).

[0086] Referring to FIG. 5b, Comparative Example 7 has four coupling holes (H11b, H12b, H13b, H14b) formed in the first yoke (100), four coupling holes (H21b, H22b, H23b, H24b) formed in the second yoke (200), two coupling holes (H31b, H32b) formed in the first leg (300), two coupling holes (H41b, H42b) formed in the second leg (400), and two coupling holes (H51b, H52b) formed in the third leg (500).

[0087] Referring to FIG. 5c, Comparative Example 8 has two coupling holes (H11c, H12c) formed in the first yoke (100), two coupling holes (H21c, H22c) formed in the second yoke (200), three coupling holes (H31c, H32c, H33c) formed in the first leg (300), three coupling holes (H41c, H42c, H43c) formed in the second leg (400), and three coupling holes (H51c, H52c, H53c) formed in the third leg (500).

[0088] Hereinafter, the description will be made with reference to Table 2. In Table 2, the number of coupling holes is sequentially listed as first yoke (100) / second yoke (200) / first leg (300) / second leg (400) / third leg (500), and the power loss that appears when the secondary winding is opened and the rated voltage is applied to the primary winding while the winding part is wound around the iron core is defined as the rated no-load loss, and the first embodiment as shown in Fig. 3a is set as the reference value and the no-load loss is expressed as 100%. In addition, considering the variability of the voltage, the no-load loss was evaluated by applying more than 10% of the rated voltage. The proportional value for the no-load loss of the first embodiment as shown in Fig. 3a is expressed as a relative ratio (%). The second embodiment refers to Fig. 3b, and the third embodiment refers to Fig. 3c. And, although the fifth embodiment is not shown in the drawing, it is a case where the center of the third leg (500) in the first embodiment is changed to one joining hole.

[0089] No-load loss of the rated voltage of the coupling hole (%) No-load loss of voltage exceeding 10% of the rated voltage (%) Comparative example 64 / 4 / 3 / 3 / 3 106.5 108.3 Proportional example 74 / 4 / 2 / 2 / 2 104.6 106.9 Comparative example 82 / 2 / 3 / 3 / 3 102.6 104.4 First embodiment 2 / 2 / 2 / 2 / 2 100 100 Second embodiment 2 / 2 / 1 / 1 / 1 98.4 97.7 Fifth embodiment 2 / 2 / 2 / 2 / 199.3 98.4 Third embodiment 1 / 1 / 1 / 1 / 1 197.8 96.9

[0090]

[0091] According to the above table, it can be seen that the coupling holes of the yoke portion (100, 200) have a greater effect on the no-load loss than the coupling holes of the leg portions (300, 400, 500), and it can be seen that the no-load loss decreases as the number of coupling holes decreases. In the second embodiment, two coupling holes were formed in the yoke portions (100, 200) and one hole was formed in the leg portions (300, 400, 500), and in the fifth embodiment, two coupling holes were maintained in the yoke portions (100, 200) and two coupling holes were formed in the first leg (300) and the second leg (400) located on the outer side among the leg portions (300, 400, 500). The fifth embodiment is effective because it has excellent no-load loss and easy core assembly. In the third embodiment, the number of coupling holes was formed as 1 in all core sub-parts (100, 200, 300, 400, 500), and the no-load loss of the third embodiment was the best, but care must be taken not to twist the core when assembling it, and continuous observation may be required to maintain alignment even after fixing with a coupling member such as a bolt, so there may be some difficulty in manufacturing convenience. The reason why the difference in no-load loss at a voltage exceeding 10% is greater than the no-load loss at the rated voltage is because the magnetic flux density increases by the amount of the applied voltage, and leakage flux occurs due to local saturation of the magnetic field within the core, but compared to the comparative examples, the first to fourth embodiments show much better characteristics.

[0092] Therefore, the transformer core according to one embodiment of the present invention can provide the effect of reducing no-load loss and no-load noise and improving the performance of the transformer compared to a conventional core.

Claims

1. A core sub-part including a plurality of steel plates laminated and having a connecting hole penetrating in the lamination direction, the number of the connecting holes being 2 or less, A transformer core in which a plurality of the core sub-parts are arranged in a direction intersecting the stacking direction.

2. In paragraph 1, The above core subpart is, One of a first yoke arranged parallel to a first direction intersecting with the stacking direction, a second yoke arranged parallel to the first yoke and spaced apart from the first yoke, a first leg arranged between the first yoke and the second yoke and in a second direction intersecting with the stacking direction and the first direction, a second leg arranged parallel to and spaced apart from the first leg, or a third leg arranged parallel to and spaced apart from the first leg and the second leg, A transformer core, wherein at least one of the plurality of core sub-parts has one coupling hole.

3. In paragraph 2, A transformer core, wherein at least one of the first leg, the second leg, and the third leg has one coupling hole.

4. In paragraph 2, A transformer core having a number of coupling holes included in the third leg of the transformer.

5. In paragraph 1, A plurality of the above core sub-parts are joined to form a closed cross-section, The first length in the longitudinal direction intersecting the lamination direction is longer than the second length in the width direction intersecting the lamination direction and the longitudinal direction, A transformer core in which the position of the above-mentioned coupling hole is located at a distance of 0.45 to 0.70 times the second length based on one end close to the closed cross-section in the width direction based on the second length.

6. In paragraph 5, A transformer core in which the position of the above-mentioned coupling hole is located at 0.55 to 0.60 times the second length.

7. In paragraph 2, One coupling hole is formed in the first yoke and the second yoke, A transformer core in which the first coupling hole formed in the first yoke and the second coupling hole formed in the second yoke are not arranged in a straight line in the second direction.

8. In paragraph 4, The position of the coupling hole included in the third leg is a transformer core located at the center of the third leg in the first direction and the second direction.

9. A yoke section including a first yoke in which a plurality of steel plates are laminated and arranged parallel to a first direction intersecting the lamination direction of the steel plates, and a second yoke arranged parallel to and spaced apart from the first yoke; and A leg section including a plurality of steel plates laminated, a first leg connected to the first yoke and the second yoke and arranged in a second direction intersecting the first direction, and a second leg arranged parallel to and spaced apart from the first leg; The above yoke portion and the above leg portion are combined to form a closed rectangular cross-section, A connecting hole is formed through the stacking direction in the above yoke portion or the above leg portion, A transformer core, wherein the number of coupling holes formed in each of the first yoke, the second yoke, the first leg, or the second leg is 2 or less.

10. In paragraph 9, The above leg part, A third leg is included that is parallel to the first leg and the second leg and is positioned within the closed rectangular cross-section, A transformer core having one coupling hole formed in the center of the third leg in the first direction and the second direction.

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