JP2775221B2 - Transformer core - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transformer for reducing the inrush current of an excitation in a core of a transformer constructed by loading a blanking block comprising a plurality of blanks such as silicon steel sheets. Regarding the product core.

[0002]

2. Description of the Related Art An exciting inrush current of a transformer is applied when the instantaneous value of the power supply voltage is "0", and when the direction of the remanent magnetism in the iron core coincides with the direction of the magnetic flux immediately after the voltage is applied. In this case, the maximum value imax of the current in the first cycle at which the exciting inrush current becomes maximum is expressed by the following equation.

Imax = NA (2Bm + Br-2) / L (N: number of windings of exciting winding, A: sectional area of iron core,
L: air-core inductance of the exciting winding, Bm: normal magnetic flux density, Br; residual magnetic flux density) As is apparent from this equation, in order to reduce the maximum value imax of the exciting inrush current, the normal magnetic flux density Bm is reduced. It can be seen that it is effective to reduce the residual magnetic flux density Br.

In order to reduce the normal magnetic flux density Bm, it is conceivable to set the sectional area A of the iron core to a large value or to increase the number of turns N of the exciting winding.

On the other hand, when reducing the residual magnetic flux density Br, a butt gap 5 as shown in FIG.
It is conceivable to provide 5,55 positively.

[0006]

[0007] However, in the former, for example, enlargement of the ascertained by routine flux density trying B _m to 1/2 and the transformer volume equivalently doubled transformer, cost, etc. And the problem that the impedance voltage and the voltage fluctuation rate increase.

On the other hand, in the latter, as described later,
Although the residual magnetic flux density can be greatly reduced, a large oscillating force acts on the butt gap, causing the butt gap to become a noise source. In comparison, there is a problem that some special measures must be taken to firmly fix the iron core.

The present invention has been made in view of the above problems, and has been described with reference to FIG.
Without providing the butt gaps 55 and 55 as in the case of the iron core with a gap as shown in FIG. 1, the product which can reduce the residual magnetic flux density and reduce the exciting rush current by a structure similar to the iron core of a general transformer. The purpose is to provide an iron core.

[0009]

In order to solve the above-mentioned problems, a core of a first transformer according to the present invention is constituted by stacking a blanking block made up of a plurality of blanking plates. In a transformer core in which a seam gap is formed between yokes, the seam gap is a blanking block.
Are formed alternately so as not to be in the same position for each layer of
Together, characterized by comprising a non-magnetic insulator disposed between each layer of punched adjacent blocks.

[0010] The iron core of the second transformer according to the present invention is constituted by stacking a blanking block composed of a plurality of blanks, and forming a seam gap between the iron core leg and the yoke. The seam gap
However, be careful not to be in the same position for each layer of the blanking block
While being formed alternately, it characterized by comprising disposed is punched block nonmagnetic metal material between the layers of the adjacent.

[0011]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view of a part of a core of a transformer according to an embodiment, and FIG. 2 is a sectional view of the core of FIG.
FIG. 3 is a plan view of the iron core shown in FIG. 1 as viewed from the direction of the arrow III.

1 to 3, reference numeral 1 denotes a left iron core leg;
Denotes a right iron leg, and 3 denotes an upper yoke. In addition,
Although not shown, a lower yoke exists.

The left iron leg 1 is composed of n punched blocks 10
₁ , 10 ₂ , 10 ₃ , 10 ₄ ,..., 10 _n . Punched blocks 10 ₁ includes only a punched blocks 10 _a, punched block 10 _a is the m sheets thickness 0.3
Sheet metal 100 ₁ , 100 made of silicon steel sheet of about 5 mm
₂ , ..., 100 _m . The other blanking blocks 10 ₂ , 10 ₃ , 10 ₄ ,..., 10 _n are respectively
A punched blocks 10 _a, constituted by this punched block 10 _a lamellar non-magnetic insulator 10 _b disposed on one side of the. Here, the nonmagnetic insulator _10b is made of an FRP plate, polyamide paper, kraft paper, or the like.

The right iron leg 2 is composed of n punched block members.
Qu 20₁ , 20_Two , 20_Three , 20 _Four , ..., 20_n By
And each punching block 20₁ , 20_Two , 20_Three ,
20_Four , ..., 20_n Is the blanking block of the left iron leg 1.
10₁ , 10_Two , 10_Three , 10_Four , ..., 10_n alike
It is configured.

The upper yoke 3 is composed of n punched-out blocks.
K30₁ , 30_Two , 30_Three , 30_Four, ..., 30_n By
Each of the blanking blocks 30₁ , 30_Two , 30_Three ,
30 _Four , ..., 30_n Is the blanking block of the left iron leg 1.
10₁ , 10_Two , 10_Three , 10_Four , ..., 10_n alike
It is configured. Note that the lower yoke (not shown)
However, the configuration is the same as that of the upper yoke 3.

The blanking blocks 30 ₁ , 30 of the upper yoke 3
_2, 30 _3, 30 _4, ..., 30 _n, as is clear from FIG. 1, punched blocks 30 ₁ in the odd-numbered columns, 30 _3, the ... right portion and the even rows of punched block set 30 _2, 30 ₄ , ...
The left-hand side of is overlapped with the odd-numbered blanking block group 3
0 _1, 30 _3, left part of ... is punched blocks 10 ₂ of the even columns of the left core legs 1, 10 _4, overlaps the ... upper portion of punched blocks of even-numbered columns 30 _2, 30 _4, The right-hand side of… is an odd-numbered stripped block group 2 of the right iron leg 2
0 _1, 20 _3, are arranged to overlap the ... upper part of the.

Then, the blanked block groups 30 ₁ ,
30 _3, and the lower end surface of the ... left portion of the gap of the seam 4 is formed between the left punched blocks 10 ₁ of the odd-numbered columns core legs 1, 10 _3, ... the upper end surface of the. The gap 4 at the seam is a slight gap between the blanking block groups 30 ₁ , 30 ₃ ,... And the blanking block groups 10 ₁ , 10 ₃ ,.

Further, even-numbered blanking block groups 30 ₂ , 3
0 _4, and ... left end surface of the left core punched blocks 10 ₂ of the even row of legs 1, 10 _4, also between the ... right end surface of the upper part of, the same seam as the gap 4 of the seam A gap 5 is formed. In addition, an odd-numbered blanking block group 3
0 _1, 30 _3, and ... right end surface of the, punched blocks 20 ₁ of the odd-numbered columns of the right core leg 2, 20 _3, between the ... left end surface of the upper portion, and, punched blocks in the even columns 30 ₂ , 30
_4, the lower end surface of the ... right portion of punched blocks 20 ₂ of the even rows of the right core leg 2, 20 _4, also between the upper ends plane of a respective similar to gap 4 and 5 of the joint The gaps 6, 7 of the seam are formed.

Next, the operation of the above-structured iron core will be considered with reference to FIG. FIG. 4 shows a joint portion between the left iron core 1 and the upper yoke 3, and is a partially enlarged cross-sectional view along IV-IV shown in FIG. Each joint between the upper yoke 3 and the right iron leg 2, between the right iron leg 2 and the lower yoke, and between the lower yoke and the left iron leg 1 is also shown in FIG.

Here, as shown in FIG.
Flux A which has flowed a punched block ₁₀₇ from below
₇₁ is the magnetic resistance of the gap 4 of the seam and the non-magnetic insulator 1
Depending on the ratio of the magnetic resistances 0 _b and 30 _{b to} the magnetoresistance, some
Moves to punched blocks 30 ₇ of the upper yoke 3 through the gap of the seam 4, as shown in the illustrated dashed arrow A _73, the other part is a non-magnetic insulator 10 as shown in Figure 4 shown solid arrows
_b, moves to punched block 30 ₇ through punched blocks 10 _a, a nonmagnetic insulator 30 _b in this order. Further, the magnetic flux A ₇₂ that has flowed a punched block ₁₀₇ of the left core legs 1 from below,
Depending on the ratio of the magnetoresistance and the magnetic resistance of the non-magnetic insulator 10 _b of the gap of the seam 4, in part, Figure 4 indicated by broken line arrows A
Moves to punched blocks 30 ₇ of the upper yoke 3 through the gap of the seam 4, as shown at _74, the other part, Fig. 4 illustrates a solid line as indicated by arrow nonmagnetic insulator 10 _b, punched block 10 _a moves to punched block 30 ₇ nonmagnetic insulator 10 _b through sequentially.

[0022] However, when the magnetic flux density of the magnetic flux flowing inside the product core is high, the magnetic flux A ₇₁ each punched blocks _{106, 108} is that due to the substantially magnetically saturated state, has flowed inside punched block _107, A ₇₂ is a dashed arrow A ₇₃ , A shown in FIG.
As shown at _74, it passes to punched block 30 ₇ both straight pass through the gap of the seam 4.

As described above, the left iron core leg 1 and the upper yoke 3
At the joint between the non-magnetic insulators 10 _b and 30 _b between the blanking blocks 10 _a and 30 _a adjacent to each other.
Are disposed, the magnetic flux flowing from below in each of the stripped blocks 10 ₁ , 10 _3, ... Of the odd-numbered rows of the left iron leg 1 is removed from the gap 4 of the joint or the non-magnetic insulators 10 _b , 30.
You must pass one of _b . This means that a significant reduction in residual magnetic flux density can be achieved as described below.

That is, a case where a normal magnetic flux density is 1T in an iron core having a magnetic path length of 1 m having a gap of a total of 0.1 mm will be described as an example. The relationship between the magnetic flux density in the iron core portion and a required magnetomotive force is as follows. Assuming that there is no change in the material properties due to the material processing and the assembling of the iron core, it is represented by a curve as shown in FIG. on the other hand,
The relationship between the magnetic flux density at the gap and the required magnetomotive force is represented by the following equation: magnetic flux density = 4 × 10 ⁻⁷ /(0.1×10 ⁻³ ), and FIG. It is represented by a straight line as shown by.

Therefore, the relationship between the magnetic flux density and the magnetomotive force in the entire iron core can be represented by a curve as shown in FIG. 6 by combining FIG. 5 (1) and FIG. 5 (2). The shapes and the diagram shown in FIG. 6 5 shown figure (1) and as is clear from the comparison as an example, the residual magnetic flux density B _r of the core without gaps while a 0.7 (T), the gap remanence B _r is 0.06 (T) next to the core of the incoming, it can be seen that the remanence B _r is greatly reduced.

However, in the case of a conventional laminated iron core having a general structure, when the magnetomotive force applied to the iron core is reduced to zero, in other words, when the voltage applied to the excitation winding is released, the magnetic flux is reduced as shown in FIG. the gap 104 of a large joint of the resistor will be diverted, in practice the effect of a significant decrease in remanence B _r by gaps 4 of the seam as described above has not been able to exert.

On the other hand, according to the present embodiment, adjacent to each other
Blanking block 10 in contact_a , 30_aNon-magnetic insulator 1 between
0_b , 30_b The arrangement of
When the voltage application is released, the magnetic flux
Or non-magnetic insulator 10_b , 30_b That will remain through
And For the magnetic flux passing through the gap 4 at the seam,
Gap 4 at the seam acts as a gap, while non-magnetic
Insulator 10_b , 30 _b Non-magnetic for magnetic flux passing through
Insulator 10_b , 30_b Acts as a gap,
The size of the gap 4 at the seam, the non-magnetic insulator 10_b , 3
0_b By properly designing the thickness of each passage,
The residual magnetic flux density can also be reduced. And the residual magnetic flux density B_r 
, The normal magnetic flux density B_m Set to a higher value
Will be able to However, the seam gap
4 is a blanking block group 30 even if it is not actively inserted.₁ , 3
0_Three , ... and punched block group 10₁ , 10_Three Join with…
It may be only the gap that is inevitably generated when it is performed. Non-magnetic
In order to make the edge work as a gap,
Hysteresis curve, number of blanks per block,
The area where the leg strip and the yoke strip oppose each other,
The thickness is determined in consideration of the facing area and the like.

Next, the effects of the present invention will be roughly shown. In general transformers, ascertained by routine flux density B _m is 1.5 (T), remanence B _r is 80% of the ascertained by routine magnetic flux density B _m 1.2
(T), K = N · A / L, then i _max = K (2 × 1.5 + 1.2-2) = 2.2K. On the other hand, if a non-magnetic insulator is inserted into this transformer to set the residual magnetic flux density _Br to 0.1 (T), then i _max = K (2 × 1.5 + 0.1-2) = 1 .1K, and the exciting inrush current is reduced by half.

Conversely, if the normal magnetic flux density is reduced to 1.1K by reducing the normal magnetic flux density while the iron core structure remains the same, when the residual magnetic flux density is calculated as 80% of the normal magnetic flux density, the normal magnetic flux density becomes 1 .11 (T). Actually, if the normal magnetic flux density is reduced, the value of K changes, but the normal magnetic flux density still needs to be greatly reduced.

Next, a transformer in which the exciting rush current is suppressed to about the rated current will be examined. When the normal magnetic flux density is inversely calculated by setting the right side to approximately “0” in the above equation, in the case of a general transformer, the residual magnetic flux density is 0.714 (T) when the residual magnetic flux density is 80% of the normal magnetic flux density. . On the other hand, when a butt gap is inserted into the iron core leg, or non-magnetic insulators 10 _b and 30 _b are inserted between the blanking blocks 10 _a and 30 _a adjacent to each other, and the residual magnetic flux density is set to 0.1 (T). Is 0.9
5 (T). That is, when the residual magnetic flux density is 0.1 (T), the design magnetic flux density can be as high as 1.33 times. On the other hand, the manufacturing cost of the transformer is 0.3 to 1 power of the equivalent capacity (usually 0.65
Power). Since the equivalent capacitance is inversely proportional to the design magnetic flux density, the manufacturing cost of the transformer will be inversely proportional to the design magnetic flux density to the power of 0.3 to 1.0 (usually the power of 0.65).

Therefore, assuming that it is inversely proportional to the 0.65 power, a trial calculation in which a non-magnetic insulator is inserted is 83% more expensive than a method in which the magnetic flux density is simply reduced.
Taking into account the increase in non-magnetic insulators and the number of manufacturing steps,
Cost reduction of several percent can be expected.

However, the cost in the case of a significant change in the structure cannot be generally discussed as described above. Even with the same method for reducing the residual magnetic flux, if the above-mentioned structure is used in which the butt gap is inserted into the iron core leg, the cost must be increased accordingly.

However, in the case of a transformer having a large capacity, when it is necessary to reduce the inrush current to a great extent as compared with a general transformer, there is an effect of providing a butt gap. In the case of a small-capacity transformer, the rate of cost increase for inserting a butt gap increases, and it is often more advantageous not to insert a gap even if the magnetic flux density is greatly reduced.

The transformer for preventing inrush current of the present embodiment has a low residual magnetic flux density without a butt gap, and is therefore very economically advantageous because its structure is similar to a general transformer. . In addition, the increase in the voltage fluctuation rate is smaller than that of a transformer in which the magnetizing inrush current is dealt with only by reducing the magnetic flux density, and there is no noise problem due to the gap that is often present in a butt gap input transformer, and the characteristics are also low. It is a well-balanced transformer with few disadvantages.

FIG. 7 shows another embodiment of the present invention, in which a non-magnetic metal body (for example,
In the stacked iron core on which the copper plate, the copper strip, the aluminum strip, and the aluminum strip are arranged, the joint portion between the left iron core leg 1 and the upper yoke 3 is shown in the same manner as in FIG. 4 described above. FIG. 3 shows a partially enlarged sectional view by a cut surface. Each joint between the upper yoke 3 and the right iron leg 2, between the right iron leg 2 and the lower yoke, and between the lower yoke and the left iron leg 1 is also shown in the same manner as in FIG.

A non-magnetic metal body is disposed between the blanking blocks.
In this case, as shown in FIG.
10₇ A flowing from below₇₁Is a non-magnetic metal body
10 _b , 30_b Fig. 7
As shown by the solid line arrow,
Blanking block 30 of upper yoke 3₇ Move on to Also on the left
Stripping block 10 of iron core 1₇ Magnetism flowing from below
Bundle A₇₂Is the joint gap as shown by the solid arrow in FIG.
Piercing block 30 of upper yoke 3₇ To
Move on.

As described above, the left iron core 1 and the upper yoke 3
At the joint between the non-magnetic metal members 10 _b , 30 _b between the blanking blocks 10 _a , 30 _a adjacent to each other.
Is arranged, the magnetic flux flowing from the inside of each of the stripped blocks 10 ₁ , 10 _3, ... Of the odd-numbered rows of the left iron leg 1 from below must be passed through the gap 4 of the joint.

When the application of voltage to the excitation winding is released, the non-magnetic metal members 10 _b and 30 _b do not completely block the magnetic flux, so that the magnetic flux is supplied to the gap 4 of the seam or the non-magnetic metal. through one of the body 10 _b, 30 _b is assumed to remain. Here, the gap 4 of the seam acts as a gap for the magnetic flux passing through the gap 4 of the seam, while the nonmagnetic metal bodies 10 _b and 30
_{For the} magnetic flux passing through _b , the non-magnetic metal bodies 10 _b and 30 _b
Act as a gap. Therefore, by appropriately designing the size of the gap 4 at the seam and the thickness of the nonmagnetic metal members 10 _b and 30 _b , the residual magnetic flux density in any of the paths can be reduced. Then, due to a significant decrease in remanence B _r, it is possible to set the ascertained by routine magnetic flux density B _m to a higher value.

Therefore, according to this embodiment, the same effect as that of the above-mentioned embodiment, that is, since the residual magnetic flux density is reduced without inserting a butt gap, the structure is similar to that of a general transformer. It is very advantageous, and the increase of the voltage fluctuation rate is small compared to the transformer that deals with the exciting inrush current only by reducing the magnetic flux density, and there is no noise problem due to the gap that is common in butt gap transformers In addition, an effect that the characteristics can be balanced can be obtained.

FIGS. 8 to 10 show still another embodiment of the present invention, and show a laminated core in which non-magnetic insulators are provided on both sides of a blanking block of a yoke. Here, FIG. 8 is a view similar to FIG. 2 of the above-described embodiment, in which the iron core shown in FIG.
9 is a plan view of the core shown in FIG. 1 as viewed from the direction of arrow III, similarly to FIG. 3. Further, FIG. 10 is similar to FIG.
FIG. 3 shows a joining portion between the upper yoke 3 and FIG.
5 shows a partially enlarged cross-sectional view of the same cut surface as that of FIG.

In the stacked iron core according to this embodiment, the left iron core
The leg 1 includes n punched blocks 10₁, 10_Two , 10_Three ,
10_Four , ..., 10_n Composed of each blanking block
10 ₁ , 10_Two , 10_Three , 10_Four , ..., 10_n Is m
Punching 10 made of silicon steel sheet having a thickness of about 0.35 mm
0₁ , 100_Two , ..., 100_m Composed of

The right iron leg 2 is composed of n punched block members.
Qu 20₁ , 20_Two , 20_Three , 20_Four, ..., 20_n By
And each punching block 20₁ , 20_Two , 20_Three ,
20 _Four , ..., 20_n Is a stamped sheet made of m silicon steel sheets
200₁ , 200_Two , ..., 200_m Composed by
You.

The number of upper yokes 3 is n or (n
+2) pieces of blanking blocks 30 ₁ , 3 with non-magnetic insulator
0 _2, 30 _3, 30 _4, ..., constituted by 30 _n. Here, the reason why the number is (n + 2) is to prevent a decrease in the cross-sectional area of the yoke. You. Each blanking block 30 ₁ with non-magnetic insulator,
_{30 2, 30 3, 30 4} , ..., 30 n is punched 300 _1, 300 ₂ consisting of k pieces of silicon steel sheets, ..., and punched block 30 _a composed of 300 _k, the punched block Nonmagnetic insulators 30 _b , 3 arranged on both sides of 30 _a
0 constituted by and _c. Note that the lower yoke is configured similarly to the upper yoke 3.

Next, the operation of the above-structured iron core will be discussed with reference to FIG.

[0045] As shown in FIG. 10, the magnetic flux A ₇₁ that has flowed a punched block ₁₀₇ of the left core legs 1 from below, the gap of the seam 4 Magnetoresistance and non-magnetic insulator 30 _b between the magnetic resistor In accordance with the ratio, a part is indicated by a dashed arrow A _{73 in} FIG.
It passes through the gap of the seam 4, as shown by the routine goes to a punched blocks 30 ₇ of the upper yoke 3 and the other portion is punched block ₁₀₆ as shown in Figure 10 shown solid arrows, a non-magnetic insulator 30 _b Turning to punched block 30 ₇ through sequentially. Also,
Flux A ₇₂ that has flowed a punched block ₁₀₇ of the left core legs 1 from below, depending on the ratio of the magnetic resistance of the magnetic resistance and the non-magnetic insulator 30 _c of the gap of the seam 4, a portion, FIG. 1
0 passes through the gap of the seam 4, as shown in the illustrated dashed arrow A ₇₄ passes to punched blocks 30 ₇ of the upper yoke 3 and the other portion is punched block 1 as shown in Figure 10 shown solid arrows
0 _8, punched block 3 nonmagnetic insulator 30 _c through the order
Turning to 0 _7.

However, when the magnetic flux density of the magnetic flux flowing inside the laminated core is high, since each of the blanking blocks 10 ₆ and 10 ₈ is substantially in a magnetically saturated state, the magnetic flux A ₇₁ , which has flowed inside the blanking block 10 ₇ , A ₇₂ is a dashed arrow A ₇₃ shown in FIG.
As shown by A _74, moves to punched block 30 ₇ both straight pass through the gap of the seam 4.

Therefore, according to the present embodiment, the same effect as that of the above-described embodiment, that is, the residual magnetic flux density is reduced without inserting a butt gap, the structure becomes similar to that of a general transformer. It is very advantageous, and the increase of the voltage fluctuation rate is small compared to the transformer that deals with the exciting inrush current only by reducing the magnetic flux density, and there is no noise problem due to the gap that is common in butt gap transformers In addition, an effect that the characteristics can be balanced can be obtained.

FIG. 11 shows still another embodiment of the present invention, in which a left iron core 1 is provided in a stacked iron core in which a non-magnetic metal body is disposed on both sides of a punched block of a yoke, as in FIG. FIG. 3 shows a connecting portion between the upper yoke 3 and the upper yoke 3.
FIG. 5 shows a partially enlarged cross-sectional view taken along the same cutting plane as V. FIG.

[0049] As shown in FIG. 11, the magnetic flux A ₇₁ that has flowed a punched block ₁₀₇ of the left core legs 1 from below, which can not pass through the non-magnetic metal member 30 _b, 11
Turning to punched blocks 30 ₇ of the upper yoke 3 through the gap of the seam 4, as shown in the illustrated solid-line arrow. Further, the magnetic flux A ₇₂ that has flowed a punched block ₁₀₇ of the left core legs 1 from below, punched block 30 of the upper yoke 3 through the gap of the seam 4, as shown in Figure 11 shown solid arrows
Move to ₇ .

As described above, the left iron leg 1 and the upper yoke 3
The non-magnetic metal members 30 _b and 30 _c are provided on both sides of each of the stripping blocks 30 _a of the upper yoke 3 at the joints between them, so that each of the stripping blocks in the odd-numbered rows of the left iron core leg 1. 10 ₁ , 10 ₃ ... The magnetic flux flowing from below inside must be passed through the gap 4 of the joint.

Therefore, by disposing the non-magnetic metal members 30 _b and 30 _c on both surfaces of the blanking block 30 _a of the upper and lower yokes 3, the magnetic flux causes the seam gap 4 as described above in a steady state. I have to pass. However, when the voltage application to the excitation winding is released, the non-magnetic metal body 3
0 _b , 30 _c does not completely block the magnetic flux, so it is assumed that the magnetic flux remains through either the gap 4 of the seam or the non-magnetic metal body 30 _b , 30 _c . Here, with respect to the magnetic flux passing through the gap of the seam 4, the gap of the seam 4 acts as a gap, whereas, for the magnetic flux through the non-magnetic metal member 30 _b, 30 _c, a non-magnetic metal member 30 _b , 30 _c acts as a gap. Therefore, by appropriately designing the size of the gap 4 at the seam and the thickness of the nonmagnetic metal members 30 _b and 30 _c , the residual magnetic flux density in any of the passages can be reduced. And
The significant decrease in remanence B _r, ascertained by routine flux density B
_m can be set to a higher value. However,
Even if the seam gap 4 is not positively inserted, it is inevitable when the blanking block groups 30 ₁ , 30 ₃ ,... And the blanking block groups 10 ₁ , 10 ₃ ,. The resulting gap alone may be used. In order for the non-magnetic metal body to have a function as a gap, the hysteresis curve of the blanking, the number of blanks per block, the area where the leg blank and the yoke blank face each other, and the area where the yoke blanks face each other The thickness is determined in consideration of the above factors.

Therefore, according to this embodiment, the same effect as that of the above-described embodiment, that is, the residual magnetic flux density is reduced without inserting a butt gap, the structure is similar to that of a general transformer. It is very advantageous, and the increase of the voltage fluctuation rate is small compared to the transformer that deals with the exciting inrush current only by reducing the magnetic flux density, and there is no noise problem due to the gap that is common in butt gap transformers In addition, an effect that the characteristics can be balanced can be obtained.

Although not shown in the drawings, as still another embodiment of the present invention, a core made of a non-magnetic insulator or a non-magnetic metal member is provided on both sides of a blanking block on the iron leg side. is there. According to this embodiment, effects similar to those of the above-described embodiments can be obtained.

The present invention is not limited to a single-phase two-legged core, but includes a single-phase three-legged core, a three-phase three-legged core,
It can be widely applied to three-phase five-legged iron cores, multi-stage iron cores, frame-shaped iron cores and the like.

[0055]

As described above, according to the present invention,
The residual magnetic flux density can be reduced, and the inrush current can be reduced.

[Brief description of the drawings]

FIG. 1 is a perspective view of a part of a core of a transformer according to one embodiment.

FIG. 2 is a side view of the stacked iron core shown in FIG.

FIG. 3 is a plan view of the stacked iron core shown in FIG. 1 as viewed from the direction of arrow III.

FIG. 4 is a partially enlarged cross-sectional view taken along the line IV-IV in FIG. 3, showing a joint portion between the left iron leg 1 and the upper yoke 3;

FIG. 5 is a graph showing a relationship between a magnetomotive force and a magnetic flux density.

FIG. 6 is a graph showing the relationship between magnetomotive force and magnetic flux density.

FIG. 7 is a side view corresponding to FIG. 2 of a core of a transformer according to another embodiment.

FIG. 8 is a plan view corresponding to FIG. 3 of the same core;

FIG. 9 is a partially enlarged cross-sectional view of the same core, corresponding to FIG. 4;

FIG. 10 is a sectional view of a core of a transformer according to still another embodiment.
Partial enlarged sectional view corresponding to

FIG. 11 is a sectional view of a core of a transformer according to still another embodiment.
Partial enlarged sectional view corresponding to

FIG. 12 is a perspective view of a core with a gap showing a conventional example of a laminated core;

FIG. 13 is a cross-sectional view showing a portion corresponding to FIG. 4 for explaining a problem of a conventional core of a general structure.

[Explanation of symbols]

1 left core legs 2 right core legs 3 York 4,5,6,7 gap of the seam _{100 1, ..., 100 m,} 200 1, ..., 200 m, 3
00 _1, ..., 300 _m punched 10 _a, 30 _a punched block 10 _b, 30 _b, 30 _c nonmagnetic insulator or a non-magnetic metal body

Claims (6)

(57) [Claims] 1. A consists are loading the punched blocks composed of a plurality of punched, in the product-core transformers gap seam between the core legs and the yoke is formed, the seam
If the gap is in the same position for each layer of the blanking block
Lest while being formed alternately, the transformer of the product core, characterized by comprising a non-magnetic insulator disposed between each layer of punched adjacent blocks. 2. A constructed are loading the punched blocks composed of a plurality of punched, in the product-core transformers gap seam between the core legs and the yoke is formed, the seam
The gap is in the same position for each layer of the blanking block
Lest while being formed alternately, the transformer of the product core, characterized by comprising disposed is punched block nonmagnetic metal material between the layers of the adjacent. 3. The core of a transformer according to claim 1, wherein the non-magnetic insulator is disposed on both sides of a blanking block of the yoke. 4. The stacked iron core of a transformer according to claim 1, wherein said non-magnetic insulator is disposed on both sides of a blanking block of said iron core leg. 5. The core of a transformer according to claim 2, wherein the non-magnetic metal member is disposed on both sides of a blanking block of the yoke. 6. The laminated iron core of a transformer according to claim 2, wherein said non-magnetic metal body is disposed on both sides of a blanking block of said iron core leg.