KR102298557B1 - Stacked core for transformer with excellent no-load loss and noise, and manufacturing method thereof - Google Patents

Abstract

In accordance with one embodiment of the present invention, a stacked core for a transformer comprises: an upper yoke and a lower yoke on which a plurality of first oriented electrical steel sheets are stacked; a plurality of legs on which a plurality of second oriented electrical steel sheets are stacked and which are disposed between the upper yoke and the lower yoke; and a plurality of coupling parts with one portion formed on at least one of the upper yoke and the lower yoke and the other portion formed on the plurality of legs, wherein the one portion and the other portion each have at least one protrusion part or at least one recessed part coupled to each other, and in accordance with the coupling of the at least one protrusion part and the at least one recessed part, the plurality of legs are coupled with at least one of the upper yoke and the lower yoke. The method for manufacturing the stacked core for a transformer comprises the steps of: cutting the plurality of oriented electrical steel sheets; forming a plurality of coupling parts each having at least one protrusion part and at least one recessed part coupled with the protrusion part on a cut surface provided to be coupled and to form a yoke and leg of a stacked core among cut surfaces of the plurality of respective oriented electrical steel sheets; coupling and stacking the coupling parts of the plurality of cut oriented electrical steel sheets so as to form a stacked core body; and fixing the stacked core body.

Description

Hematite core for transformer with excellent no-load loss and no-load noise and manufacturing method thereof

The present invention relates to a red iron core for a transformer having excellent no-load loss and no-load noise and a method for manufacturing the same.

A transformer is a device that changes AC voltage and current values by using electromagnetic induction, and is one of the essential parts for electronic products. They are manufactured by winding a winding (coil) that is an electrical conductor around a magnetic iron core. Among the coils, a primary coil is connected to an input circuit in which a voltage is to be changed, and a secondary coil is connected to an output circuit in which the changed voltage is used. Here, magnetic energy is used to connect the electrical energy of the primary coil and the secondary coil to each other. In this case, a grain-oriented electrical steel sheet with low magnetic loss is used as the iron core. The iron core is divided into a hematite core and a wound iron core, and FIG. 1 shows a hematite core.

In general, the main characteristics of a transformer are loss and noise. Transformers are divided into no-load characteristics and load characteristics depending on whether or not a power load connected to the secondary coil is used. The no-load characteristic always occurs when there is no load, regardless of whether the transformer is operating or not. On the other hand, the load characteristic occurs when power is used at the load end connected to the coil (winding), which is the secondary electrical conductor, and the load loss is determined by the Joule loss consumed in the coil (winding). Load noise appears due to the electromagnetic force of Therefore, it is a global trend to reduce no-load loss and no-load noise, which are power losses that occur every moment regardless of whether a transformer is used or not, according to eco-friendly policies, and these are systematically regulated in order to be enforced.

As a way to reduce the no-load loss, a grain-oriented electrical steel sheet with excellent iron loss is used as the iron core. As iron loss increases as the thickness of grain-oriented electrical steel sheet increases, a material with the thinnest thickness can be selected. Since excavation is not easy, the development of low iron loss materials is very difficult.

No-load noise causes a series of vibrations that repeat contraction and expansion when a magnetic field flows through the electrical steel sheet used as an iron core material. This is called magnetostriction (magnetostriction). Although research on the mechanism by which magnetostriction occurs has been continued for a long time, it is not easy to control the electrical steel sheet manufacturing process to reduce it. The reason is that, since the product standard for electrical steel is iron loss, steel companies preferentially apply manufacturing technology with excellent iron loss.

In order to solve this problem, a method and apparatus for irradiating a laser beam on the surface of an electrical steel sheet in the magnetic domain refining treatment as part of the electrical steel sheet manufacturing process in the prior art (Korean Patent Publication No. 10-1562962, Korean Patent Publication No. 10-1605793) was introduced. As a method of reducing no-load loss and no-load noise at the same time, it is a technology that can mainly be dealt with by steel companies that have related facilities.

Meanwhile, transformer manufacturers were introduced to methods of constructing iron cores. A noise reduction device (Korean Patent Publication No. 10-1855039) can be fastened to an iron core structure for a transformer formed by connecting iron cores stacked with a plurality of steel plates in a step-lap method. This is a method of fixing the exposed iron core (iron core exposed portion in FIG. 5) in the area outside the iron core joint. The shape of the iron core of the transformer is the same as in the prior art, and it is a method of reducing the vibration of the exposed electrical steel sheet by fastening a separate accessory to the outer exposed part of the iron core stacked in a step lap method. As a more advanced technology, there is a method of fixing the iron core by forming a guide slot in the thickness direction of the iron core and inserting a stacking guide capable of combining the iron core (Republic of Korea Patent Publication No. 10-2045894). These methods combine an additional accessory with a conventional iron core, and noise may deteriorate depending on the coupling state of the iron core and the accessory. In addition, when the transformer operates, an eddy current is generated in the iron core of the sheet, and there is no electrical insulation on the cut surface of the iron core, so there is a risk of an accident due to an increase in loss or a temporary spark due to electrical conduction to the coupling surface with the accessory.

In another prior art, it relates to a method of laminating an iron core. As shown in FIG. 1, it is formed as an iron core coupling part (joint), but when stacking a sheet of electrical steel, it is laminated so that the iron core spacing is configured in a W shape along the iron core thickness direction (reducing direction) (Republic of Korea Patent Publication No. 10-1302830) This increases the structural rigidity of the iron core.

In the prior art, a plurality of lamination steps are configured with a cut surface of the iron core as a straight surface (a straight surface), and a hole passing through the iron core is required as shown in FIG. 5A to fix the iron core assembly state. Alternatively, a through hole is required to form a guide slot (Republic of Korea Patent Publication No. 10-2045894) on the outside of the iron core, that is, adjacent to the outside of the iron core.

These techniques have the following problems. As shown in FIG. 1, as shown in FIG. 1, stacked sheets of electrical steel sheets in the thickness direction from as few as tens to as many as thousands of sheets, as shown in FIG. is cut in a straight line and arranged so that the cut surfaces of the iron cores face each other and stacked in the thickness direction in a step lap as shown in FIGS. 3A and 3B . When constructing a structure by stacking iron cores, there is always a problem that the iron cores are spaced apart as shown in FIG. 4A or that the alignment is uneven as shown in FIG. 4B. If the gap between the iron core and the iron core is widened or the alignment is uneven, the ideal arrangement as shown in FIGS. 4A and 4B is not achieved and the iron core is assembled into a non-uniform cross-section, which results in magnetic field leakage or a sharp increase in magnetic resistance, resulting in an increase in iron loss. A problem arises. In addition, since the cross section of the iron core coupling part is formed in a straight line, it is impossible to fix the iron core coupling part in a certain pattern. As shown in FIG. 5A , a method of fixing the iron core by forming a plurality of holes in the iron core is used. Since the magnetic resistance of the hole is very large as an air medium, as shown in Fig. 5b, the magnetic field is concentrated in the iron core material region where the hole does not exist, and as a result, the magnetic flux density is locally high as shown in Fig. 5c up to 0.3~0.5T. is formed, and harmonic components are generated in the sinusoidal magnetic field. The higher the magnetic flux density and the higher the harmonic component, the higher the iron loss of the electrical steel sheet is. In addition, since the hole size has sufficient tolerance to facilitate the process of inserting the iron core rod into the hole as shown in FIG. 5A, the separation and non-uniform alignment of the iron core coupling portion described above are caused.

6 shows the loss increase rate according to the ratio of the through-hole diameter to the width size of the iron core of the transformer.

Referring to FIG. 6 , the results of testing the iron loss increase rate according to the ratio of the actual iron core width to the hole size can be seen. That is, when defining the hole size ratio as the ratio of the hole diameter to the iron core (core) width size, it can be seen that the iron loss sharply deteriorates when the value is 4 to 5% or more. In the case of small and medium-sized transformers, since iron cores are designed with multiple combinations of core widths ranging from 80mm to 300mm, the hole size ratio is as small as 6.7% (= 20mm/300mm*100) based on the minimum hole diameter of 20mm used in industry. is 25% (=20mm/80mm*100), and it can be seen that the increase rate of iron loss is not a small number. The reason for the increase in iron loss by the through-hole size is that the bottleneck in which the magnetic field is concentrated in the iron core path without holes as shown in FIGS. This is not smooth, and the harmonic component in the sinusoidal magnetic field increases rapidly. Electrical steel sheet has a characteristic that the higher the magnetic flux density, the higher the harmonic component, the steeper the iron loss rises and deteriorates.

That is, the conventional technology has a problem in that the iron core material cost is high and it is not easy to manage the increased loss in the iron core manufacturing process.

Republic of Korea Patent Publication No. 10-1562962 Republic of Korea Patent Publication No. 10-1605793 Republic of Korea Patent Publication No. 10-1855039 Republic of Korea Patent Publication No. 10-2045894 Republic of Korea Patent Publication No. 10-1302830

According to an embodiment of the present invention, there is provided a red iron core for a transformer in which protrusions and depressions to be coupled to each other are formed on coupling surfaces of stacked iron cores, and a method of manufacturing the same.

In order to solve the problems of the present invention described above, the red iron core for a transformer according to an embodiment of the present invention is an upper yoke and a lower yoke in which a first plurality of grain-oriented electrical steel sheets are laminated, and a second plurality of grain-oriented electrical steel sheets are laminated and A plurality of legs disposed between the upper yoke and the lower yoke, one side formed on at least one of the upper yoke and the lower yoke, and the other side formed on the plurality of legs, the one side and the other side are coupled to each other A plurality of coupling portions each having at least one protrusion or depression, and coupling the plurality of legs with at least one of the upper yoke and the lower yoke according to the combination of the at least one protrusion and the at least one depression. have.

In order to solve the problems of the present invention described above, the method for manufacturing a hematite core for a transformer according to an embodiment of the present invention includes cutting a plurality of grain-oriented electrical steel sheets, combining the cut surfaces of each of the plurality of grain-oriented electrical steel sheets. forming a plurality of coupling parts having at least one protrusion and at least one recessed part engaging the protrusion on the cut surface forming the yoke and the leg of the hematite core; to form a hematite body, and fixing the stacked hematite body.

According to an embodiment of the present invention, there is an effect of suppressing the fine movement between the iron cores to lower the iron loss, which is the no-load loss, and reduce the no-load noise.

1 shows a conventional structure of a red iron core for a transformer.
2 is a two-dimensional analysis of the magnetic field flow form of the conventional structure of a hematite core for a transformer.
3A is a cross-sectional view of a stacked iron core for a transformer in a thickness direction by a conventional step wrap method, and FIG. 3B shows a three-dimensional stacked structure thereof.
4A is a front view of a conventional structure for a red iron core for a transformer that is not properly aligned in the coupling region, and FIG. 4B is a cross-sectional view viewed from the thickness direction of the iron core.
5A is a conventional structure of a red iron core for a transformer using an iron core through hole to fix an iron core coupling part, FIG. 5B shows a magnetic field flow thereof, and FIG. 5C shows a magnetic flux density distribution thereof.
6 shows the loss increase rate according to the ratio of the through-hole diameter to the width size of the transformer iron core.
7 shows a red iron core for a transformer according to an embodiment of the present invention.
8 shows a method of manufacturing a red iron core for a transformer according to an embodiment of the present invention.
9A and 9B show an embodiment of a coupling part of a hematite core for a transformer according to an embodiment of the present invention, and FIGS. 9C to 9E are projections and depressions of a coupling part of a hematite core for a transformer according to an embodiment of the present invention. Various embodiments are shown.
10a and 10b show the formation position of the coupling portion of the iron core for a transformer according to an embodiment of the present invention.
11 shows a magnetic field flow diagram in the thickness direction of the iron core according to the iron core stacking.

Hereinafter, preferred embodiments will be described in detail so that those of ordinary skill in the art can easily practice the present invention with reference to the accompanying drawings.

7 is a diagram illustrating a hematite core for a transformer according to an embodiment of the present invention, and FIG. 8 is a diagram illustrating a method of manufacturing a hematite core for a transformer according to an embodiment of the present invention.

First, referring to FIG. 7 , the red iron core 100 for a transformer of the present invention includes a yoke 110 having an upper yoke 111 and a lower yoke 112 , a plurality of legs 120 and a coupling portion 130 . may include

The plurality of legs 120 may be coupled to the upper yoke 111 and the lower yoke 112 to form the hematite core 100. For example, the plurality of legs 120 may include first to third legs ( 121, 122, 123), but is not limited thereto. In order to couple the plurality of legs 120 with the upper yoke 111 and the lower yoke 112 , the coupling part 130 is required.

The coupling part 130 may include a plurality of legs 120 , and protrusions and depressions respectively formed in the upper yoke 111 and the lower yoke 112 .

The coupling portion 130 may be provided with a plurality of (131, 132, 133, 134, 135, 136), and a plurality of coupling portions (131, 132, 1 33, 134, 135, 136) each have a protrusion and a depression. can be For example, the plurality of coupling parts (131, 132,1 33, 134, 135, 136) are first to sixth coupling parts (131, 132,1 33, 134, 135, 136) according to the number of legs. may, but is not limited thereto.

A plurality of grain-oriented electrical steel sheets may be laminated and cut, and a plurality of laminated first grain-oriented electrical steel sheets and a second plurality of grain-oriented electrical steel sheets may be laminated, and the laminated first plurality of grain-oriented electrical steel sheets is a yoke 110 The second plurality of laminated grain-oriented electrical steel sheets may constitute a plurality of legs 120 .

In order to couple the upper yoke 111 and the first to third legs 121,122 and 123, first to third coupling portions 131,132,133 are provided on corresponding cut surfaces of the plurality of grain-oriented electrical steel sheets, and the lower yoke 112 and the first In order to couple to the third legs 121 , 122 , and 123 , fourth to sixth coupling portions 134 , 135 , and 136 may be provided on corresponding cut surfaces of the plurality of grain-oriented electrical steel sheets.

Each of the first to sixth coupling parts 131 , 132 , 133 , 134 , 135 and 136 may include at least one protrusion and at least one depression coupled to the at least one protrusion. For example, looking at the region where the first coupling portion 131 is formed, the stacked first plurality of grain-oriented electrical steel sheets and the stacked second plurality of grain-oriented electrical steel sheets are combined to form the upper yoke 111 and the leg 121 . At least one depression is formed in the cut surface 131b of one side of the first plurality of grain-oriented electrical steel sheets laminated to form the upper yoke 111, and the first leg 121 is laminated to form At least one protrusion may be formed on the cut surface 131a of the other side of the second plurality of grain-oriented electrical steel sheets. This is similarly in the region where the other second to sixth coupling portions 132, 133, 134, 135, and 136 are formed, the cut surfaces 132b, 133b, 134b, At least one depression may be formed in the 135b and 136b, and the cut surfaces 132a, 133a, 134a, 135a, 136a of the second plurality of laminated grain-oriented electrical steel sheets forming the first to third legs 121, 122, and 123 have At least one protrusion may be formed. Conversely, at least one protrusion may be formed on the cut surfaces 131b, 132b, 133b, 134b, 135b, 136b of the plurality of laminated grain-oriented electrical steel sheets forming the upper yoke 111 or the lower yoke 112. At least one depression may be formed in the cut surfaces 131a, 132a, 133a, 134a, 135a, 136a of the stacked second grain-oriented electrical steel sheets forming the first to third legs 121, 122, and 123.

In order to manufacture the red iron core 100 for a transformer according to an embodiment of the present invention described above, as shown in FIG. 8 , first, a plurality of grain-oriented electrical steel sheets may be cut to an appropriate size (S10).

A plurality of cut grain-oriented electrical steel sheets may be stacked to form a yoke 110 and a plurality of legs 120 having an upper yoke 111 and a lower yoke 112, and the coupling portion 130 is a cut grain-oriented electrical steel sheet. It may be formed on the cut surface of the steel plate (S20).

A plurality of cut grain-oriented electrical steel sheets may be laminated and combined to constitute a red iron core body (S30).

In order to fix the iron core on which the electrical steel sheets are laminated, the upper and lower portions are padded with clamps and may be bound with a material made of a glass film (S40).

9A and 9B show an embodiment of a coupling part of a hematite core for a transformer according to an embodiment of the present invention, and FIGS. 9C to 9E are projections and depressions of a coupling part of a hematite core for a transformer according to an embodiment of the present invention. Various embodiments of the part are shown.

First, referring to FIGS. 9A and 9B together with FIG. 7 , a plurality of grain-oriented electrical steel sheets cut by the combination of the protrusion and the depression of the coupling part 130 of the red iron core for a transformer according to an embodiment of the present invention. It can be coupled, and in the coupling method, the protrusion of the cut surface is inserted into the depression of the cut surface facing it, so that it is possible to suppress the fine movement between the iron cores.

As described above, a plurality of grain-oriented electrical steel sheets are laminated, and the ends of the legs in which the above-described coupling portions are formed may be configured in a stepwise manner using a step lap method. That is, when the length of the end of each electrical steel sheet is configured differently at the end of the plurality of grain-oriented electrical steel sheets forming the leg, the end of the grain-oriented electrical steel sheet is viewed from the side. It may be configured to have a step (step) shape.

In the above-described step wrap method, the number of steps of a plurality of grain-oriented electrical steel sheets may be within 2 to 10 steps, and in laminating in the iron core thickness direction, a step wrap method is used to form a stepwise configuration, but the number of steps (number of steps, Ns) may be limited to within 2 to 8.

If the number of steps is composed of one step, it becomes a conventional configuration rather than a step type, and an air layer penetrates the iron core. After all, since the coupling part is composed of an air layer (void) penetrating the iron core, the magnetic resistance is very high and the leakage magnetic field is maximized, resulting in a problem in which the iron loss (loss) exceeds 15 to 30%.

That is, if the number of steps is small, a large amount of harmonic waveforms are contained in the sinusoidal magnetic field. In addition, a smooth magnetic field flow is not formed, and a magnetic field concentration phenomenon occurs, resulting in a very high local magnetic flux density. This is a factor that causes iron loss to rise. On the other hand, if the number of steps is large, since the exposed portion of the iron core for the step wrap is greatly enlarged, leakage magnetic field is severe, which leads to a problem in which iron loss is deteriorated or noise is rapidly increased.

The overlap length at which the ends of the laminated electrical steel sheets form a step, that is, the overlap length (Lovl), which is the length between the ends of adjacent electrical steel sheets forming a step among a plurality of laminated grain-oriented electrical steel sheets, may be 3 mm to 12 mm. . A maximum length (Lpp) of each of the protrusions and depressions formed at the ends of the plurality of laminated grain-oriented electrical steel sheets may be shorter than the overlap length (Lovl).

That is, when the overlap length (Lovl) is short, a large amount of harmonic waveforms are contained in the sinusoidal magnetic field. In addition, a smooth magnetic field flow is not formed and a magnetic field concentration phenomenon occurs, which increases the local magnetic flux density, which causes iron loss to increase. For this reason, the leakage magnetic field is severe, which leads to deterioration of iron loss or a sharp increase in noise.

In addition, in the iron core coupling method, the maximum length (Lpp) of the protrusion and the depression must be shorter than the overlap length (Lovl). If the maximum length (Lpp) of the protrusion and the depression is equal to or longer than the overlap length (Lovl), a section occurs in which the voids of the iron core joint coincide with the voids of the upper and lower layers in the thickness direction of the iron core, and this causes the joint to be laminated in the thickness direction As a result, a magnetic field flow is not smoothly formed, and a section in which the magnetic field is concentrated occurs as shown in FIG. 11, and thus the magnetic flux density is locally very high. If the maximum length (Lpp) of the protrusion and the depression is too short, it may be difficult to assemble the iron core. Therefore, managing the maximum length (Lpp) of the protrusion and the depression to be an appropriate size compared to the length of the overlap (Lovl) suppresses the harmonics of the magnetic field and local magnetic field concentration does not occur.

According to the embodiment of the present invention, the transformer performance is improved, such as the iron loss that is the no-load loss of the transformer is lowered and the noise is reduced.

In order to prove this, the no-load loss and no-load noise of an iron core manufactured by stacking the number of steps in 5 steps based on the above-described conventional method for manufacturing a hematite core and the manufacturing method of the present invention and having an overlap length (Lovl) of 6 mm as a standard. compared. In Example 1, the structure of the protrusion and the depression was trapezoidal, and the height (Lpp) was 2.5 mm, the narrow width was 6 mm, and the wide width was 10 mm.

Iron core manufacturing method no-load loss no load noise conventionally Straight mating + iron core through hole 106/4% 62.8 dBA Example 1 Extrude/Recessed Join 100% 58.6dBA

In the iron core of the prior art, the coupling cross-section of the coupling portion is straight, and there is a hole penetrating through the iron core. The diameter of the hole is 20mm. On the other hand, it was easy to fasten and fix the iron core by the coupling cross-section (protrusion/recession method) of Example 1 of the present invention. Compared to the prior art, the loss of Example 1 of the present invention was reduced by 6.4%, and the noise was also reduced by 4.2 dBA.

Table 2 compares the iron core manufacturing method of the present invention by fixing the overlap length (Lovl) to 6 mm and varying the number of steps of the step lap lamination.

number of steps no-load loss no load noise Example 2 2nd stage 103.5% 61.2 dBA Example 3 10 steps 103.9% 61.5 dBA Comparative Example 1 11 speed 104.6% 63.8 dBA

If the number of steps is composed of one step, the air layer at the joint of the iron core of the joint becomes one piece, and the air layer passes through the iron core. After all, since the iron core spacer consists of an air layer (void) penetrating the iron core, the magnetic resistance is very high and the leakage magnetic field is maximized, resulting in a problem that the iron loss (loss) exceeds 15-30%. Therefore, in Example 2, the number of steps was stacked in two stages, and the loss and noise were increased compared to Example 1 in Table 1, but had superior characteristics than the prior art. The loss of Example 3 and Comparative Example 1 is excellent compared to the conventional one. On the other hand, as in Comparative Example 1, when the number of steps exceeds 10, the exposed portion of the iron core due to the step wrap is enlarged, and magnetic field leakage increases.

In Table 3, in the iron core manufacturing method of Example 1, the number of steps of the step lap lamination was fixed to 5 steps, and the overlap length (Lovl) was changed for comparison.

Overlap length [mm] no-load loss no load noise Comparative Example 2 2 105.8% 64.8 dBA Example 4 3 104.2% 62.2 dBA Example 5 12 103.8% 61dBA Comparative Example 3 13 104.3% 64.2 dBA

In Comparative Example 2, the overlap length was 2 mm, the gap was very narrow, and the iron core was not stacked smoothly with a length shorter than the length of the protrusions and depressions. , especially the no-load noise is very bad. The magnetostriction of the electrical steel sheet is very vulnerable to harmonics, indicating the need for an iron core that minimizes harmonics. On the other hand, as in Comparative Example 3, when the overlap length exceeds 13 mm, a problem occurs in that the exposed portion of the iron core outside the coupling portion is enlarged, resulting in a slight increase in loss and very bad noise.

Referring to FIGS. 9C to 9E , the shapes of the protruding portion A and the concave portion B of the coupling portion may vary as illustrated. The cut surface on which the coupling portion is formed may be formed in a series of patterns composed of protrusions and depressions, and these patterns are repeatedly configured to form a plurality of pairs.

That is, the cut shape of the coupling part can be processed to be easily assembled and configured in a continuous series of patterns of protrusions and depressions as in the embodiment of the invention of FIGS. 9C to 9E . Examples of the invention indicate that it is possible to process various shapes out of the conventional straight line form, and is not limited to a specific shape. However, a gap may be formed between the protrusion existing at the boundary portion of the iron core and the depression portion of the other iron core facing the coupling portion based on the coupling portion. The wider the gap between the gaps, the more magnetic field leakage and the higher the harmonics increase rate, the greater the iron loss. The shape of the protrusion and the depression is not particularly limited and may be polygonal or elliptical, but it should be provided in a form suitable for the purpose of bonding and fixing.

10a and 10b show the formation position of the coupling portion of the iron core for a transformer according to an embodiment of the present invention.

Referring to FIG. 10A , the length of each of the plurality of coupling portions may be formed within 80% of the total length of the cut surface of the cut grain-oriented electrical steel sheet. That is, of the total length (a) from the outer side end of the cut surface to the inner corner (the inner corner adjacent to the air core), the coupling portion in the direction from the outer side end of the cut surface to the inner corner is only within the 8/10 position (b) Repeat of protrusions and depressions pattern can be formed.

Referring to FIGS. 7 and 10A , for example, in the case of the first leg 121 , a protrusion or a depression is formed at one side (C) or the other side (D) of the first coupling part 131 (b) may be within 80% of the total length (a) of one side (A) or the other side (B).

Since the flow of the magnetic flux density tends to be concentrated laterally, forming the coupling portion close to the outer side end of the cut surface may not hinder the flow of the magnetic flux density. The magnetic field has a property of flowing in a section with low magnetic resistance, which means the shortest path to form a magnetic field. On the other hand, the inside of the coupling part (the inner edge of the iron core adjacent to the air core), which is a corner section where the magnetic field rotates in a straight line, has the lowest magnetic resistance. Due to this, a large amount of magnetic field flows to the inner corner adjacent to the air core among the iron cores of the coupling part to form a high magnetic flux density, so it may not be suitable to form the protrusions and depressions inside the corners to maintain a uniform magnetic field. Some damage to the material structure occurs in the cut surface of the iron core, which may interfere with the smooth magnetic field flow, so it is necessary to form a straight cut surface at the inner corner with high magnetic flux density. Therefore, from the outer side end of the iron core (iron core exposed part by step wrap) to the inner corner (inner edge adjacent to the air core), 8/10 position from the end of the electrical steel sheet (one side (C) or the other side (D) of the coupling part) A repeated pattern of protrusions and depressions can be formed only within 80% of the total length of

Similarly, referring to FIG. 10b together with FIG. 7 , in the case of the central second leg 122 of the plurality of legs 120 , the shape of the coupling part may be similar to a triangle, and as described above, among the iron cores of the coupling part Considering that a large amount of magnetic field flows to the inner corner adjacent to the air core and high magnetic flux density is formed, a repeated pattern of protrusions and depressions on both sides of the triangle based on the triangular vertex of the end of the central second leg 122 This is formed, based on the vertex of the triangle, each of the 8/10 positions (80% of the total length of one side (C) or the other side (D) of the coupling part) out of the total length (a) only within (b) of the protrusions and a repeated pattern of depressions can be formed.

According to the present invention, by assembling and stacking the coupling method of the coupling part with the protrusion and the recessed part with the grain-oriented electrical steel sheet, the transformer performance is improved, such as lowering the iron loss, which is the no-load loss of the transformer, and reducing the noise.

The present invention described above is not limited by the above-described embodiments and the accompanying drawings, but is limited by the claims described below, and the configuration of the present invention may vary within the scope without departing from the technical spirit of the present invention. Those of ordinary skill in the art to which the present invention pertains can easily recognize that the present invention can be changed and modified.

100: hematite core for transformer
110: York
111: upper yoke
112: lower yoke
120: multiple legs
121,122,123: first to third legs
130: coupling part
131,132,133,134,135,136: first to sixth coupling parts

Claims (13)

an upper yoke and a lower yoke in which a plurality of first grain-oriented electrical steel sheets are stacked;
a plurality of legs on which a second plurality of grain-oriented electrical steel sheets are laminated and disposed between the upper yoke and the lower yoke; and
It has one side formed on at least one of the upper yoke and the lower yoke and the other side formed on the plurality of legs, the one side and the other side each having at least one protrusion or depression coupled to each other, the at least one A plurality of coupling parts for coupling the plurality of legs and at least one of the upper yoke and the lower yoke according to the coupling of the protrusion and the at least one recessed part of the
The protrusion or depression in the one side or the other side of the plurality of coupling parts is formed within 80% of the total length of the one side or the other side in a direction from the outer side end of the iron core toward the inner corner. delete According to claim 1,
A red iron core for a transformer in which a plurality of protrusions and depressions are alternately formed on one side and the other side of the plurality of coupling parts. According to claim 1,
The first and second plurality of grain-oriented electrical steel sheets are stacked iron core for a transformer in a step lap method. 5. The method of claim 4,
The number of steps of the plurality of grain-oriented electrical steel sheets and the second plurality of grain-oriented electrical steel sheets stacked in the step wrap method is 2 to 10 for a transformer red iron core. 5. The method of claim 4,
The first plurality of grain-oriented electrical steel sheets and the second plurality of grain-oriented electrical steel sheets laminated in the step wrap method have an overlap length between steps with adjacent electrical steel sheets, that is, an overlap length of 3 mm to 12 mm. 7. The method of claim 6,
The length of the depressions or protrusions of one side of the first plurality of grain-oriented electrical steel sheets stacked in the step wrap method and the other side of the second plurality of grain-oriented electrical steel sheets is shorter than the overlap length. cutting a plurality of grain-oriented electrical steel sheets;
Forming a plurality of coupling portions having at least one protrusion and at least one recessed portion coupled to the protrusion on the cut surfaces that are joined among the cut surfaces of the cut plurality of grain-oriented electrical steel sheets to form the yokes and legs of the red iron core;
forming a red iron core body by combining and stacking coupling portions of the cut plurality of grain-oriented electrical steel sheets; and
A step of fixing the laminated hematite body,
The step of forming the plurality of coupling portions includes forming the length of each of the plurality of coupling portions within 80% of the total length of the cut surface of each of the cut electrical steel sheets in the direction from the outer side end of the iron core toward the inner corner. A method of manufacturing an iron core. delete 9. The method of claim 8,
The step of laminating to form the red iron core body is a method of manufacturing a transformer red iron core by stacking each of the cut grain-oriented electrical steel sheets in a step lap method. 11. The method of claim 10,
A method of manufacturing a red iron core for a transformer in which the number of steps of a plurality of laminated grain-oriented electrical steel sheets is 2 to 10. 11. The method of claim 10,
The overlap length, which is a length between steps with an adjacent electrical steel sheet among the plurality of laminated grain-oriented electrical steel sheets, is 3 mm to 12 mm. 13. The method of claim 12,
The lengths of the depressions and protrusions of each of the plurality of laminated grain-oriented electrical steel sheets are shorter than the overlap length.

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