JP2000200722A - Three-phase transformer iron core - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the iron loss and noise by properly varying the joint angle between a leg iron part and a yoke part within a 90 deg. range. SOLUTION: This three-phase transformer iron core has a width WY of yoke iron core raw plates 13a and 14a larger than the width WL of leg iron core raw plates 10a, 11a, and 12a, a sectional area of yoke parts 13 and 14 larger than that of leg iron parts 10, 11, and 12, the angles θS between both the lengthwise ends of the leg iron core raw plates 10a to 12a contacting the yoke iron core raw plates 13 and 14a of tan-1(WL/WY)( deg.), the angles between the yoke iron core raw plates 13a and 14a contacting the leg iron core raw plates 10a to 12a of 90-θS( deg.), and the angle θC between the yoke iron core raw plates 13a and 14a and a center leg 12 of 90 deg..

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a three-phase transformer core, and more particularly to a three-phase transformer core having reduced iron loss and noise characteristics.

[0002]

2. Description of the Related Art Three-phase transformer cores which have been generally used in the past have been variously improved and improved in terms of energy saving and resource saving. FIG. 10 shows a three-phase transformer core A generally used so far.
Reference numerals 1 and 1 denote outer legs, and 2 denotes a center legs. Reference numerals 3 and 4 denote the upper and lower yoke portions, respectively.

[0003] Each of the leg iron parts 1, 1, 2 and the yoke parts 3, 4 is formed by laminating a predetermined number of core plates made of, for example, highly oriented magnetic steel sheets or directional magnetic steel sheets. The leg iron portions 1 and 1 are each formed by cutting a predetermined number of leg iron core plates 1a and 1b each having a trapezoidal outer shape with both ends cut at an angle of 45 ° with respect to the rolling direction of the electromagnetic steel plate. It is formed by laminating a predetermined number of steps by a four-step step lap joining method.

[0004] The iron leg portion 2 at the center has a V-shaped projection formed by cutting both ends of an electromagnetic steel sheet at an angle of 45 ° with respect to the rolling direction (the projection itself is cut at an angle of 90 °). Is formed by laminating a leg iron core base plate 2a having the same shape as the leg iron portions 1 and 1, and the V-shaped convex apex is formed by upper and lower yoke portions described below. Yoke iron core plate 3 constituting 3 and 4
It is formed so as to protrude to a depth of の of the width dimension of a and 4a.

The yoke core core plates 3a and 4a constituting the upper and lower yoke portions 3 and 4 are formed in a V-shape at a central portion in a longitudinal direction at a depth of 1/2 of a width dimension. It has a processed notch and is formed so as to be joined to the V-shaped projection of the central leg 2. Both ends of these yoke iron core plates 3a and 4a are cut at 45 ° so that the outer shape is trapezoidal with respect to the rolling direction of the electromagnetic steel plate, and are cut in the same manner as the leg iron core plates 1a and 1b. The three-phase transformer core A was formed by being laminated and joined to the iron legs 1, 1.

[0006]

As described above, for example, the leg iron core plates 1a and 1b and the yoke iron core plates 3a and 4a
The joint angle between the center iron core plate 2a and the yoke iron core plate 3a, 4a is 90 °, and the respective iron core plates 1a, 1b, 2a, 3a, 4a are When a three-phase transformer core A is formed by joining a plurality of sheets (in this example, four sheets are staggered and stacked in a stepwise manner (four steps) and joined by a so-called oblique joining method), the yoke of the iron core A is formed. Parts 3, 4
The magnetic flux flowing to the iron legs travels in three directions along the iron legs 1, 1, 2 so that iron loss and noise generated in the yoke portions 3 and 4 are generated in the iron legs 1, 1 and 2. There was a problem that it was higher than the noise.

Therefore, in order to solve the above-mentioned problem,
As shown in FIG. 12, the cross-sectional area of the iron legs 1A, 1B, 2A
It is conceivable that the three-phase transformer core B is formed by using the larger yoke portions 3A and 4A, thereby reducing the magnetic flux density of the yoke portions 3A and 4A and reducing iron loss. .

In the three-phase transformer core A and the three-phase transformer core B, the two types of three-phase transformer cores A and B when the average magnetic flux density of the iron leg is 1.7T. Is based on the analysis result of the magnetic field analysis by the finite element method,
For example, when the iron loss at an excitation frequency of 60 Hz is calculated, when the former iron loss value of the three-phase transformer core A is 100%, the iron loss value of the latter three-phase transformer core B is about 9%.
It was found to be reduced to 5.5%.

However, the results of magnetic field analysis of the latter three-phase transformer core B by the finite element method were confirmed.
As is clear from the magnetic flux density distribution shown in FIG. 11, the magnetic flux density is high in the center direction (white portion) of the yoke portion 3A (the yoke portion 4A is not shown), and conversely, in the width direction of the yoke portion 3A. In both end directions (black portions) becomes lower.

As a result, in the three-phase transformer core B,
There is an extreme difference in magnetic flux density between the central portion and both end portions of the yoke portions 3A and 4A. This is because the magnetic flux is applied to the yoke 3A,
The outer side (both ends of the yoke portion) of 4A is difficult to flow, while the inner side (the central portion of the yoke portion) is easy to flow. This phenomenon causes the latter three-phase transformer core B to However, there is also a problem that iron loss and noise cannot be satisfactorily reduced.

[0011] In view of the above problems, the present invention provides a three-phase transformer having a three-phase transformer having a three-phase transformer having a three-phase transformer with uniform magnetic flux density distribution, thereby reducing iron loss and noise as much as possible. To provide a transformer core.

[0012]

According to the first aspect of the present invention,
The required number of layers of leg iron core plate and yoke iron core plate
The joint position between the leg iron core plate and the yoke iron core plate.
For a three-phase transformer core that is constructed in a stepwise manner and joined diagonally
Width W of the yoke core blank_YThe legs iron core blank
Width dimension W_LMake the cross-sectional area of the yoke more wide
Outside of contact with the yoke core
Angle θ at both ends in the length direction of the iron core base plate on the side _SAnd θ_S=
tan^-1(W_L/ W_Y) [°], with outer legs iron core plate
Angle of contacting yoke iron core plate θ_YTo θ_Y= 90-θ
_S(°), and the yoke iron core plate and the center leg iron plate
Angle θ_CIs set to 90 °.

According to a second aspect of the present invention, in the three-phase transformer iron core of the first aspect, the cross-sectional area of the yoke is 1.01 to 1.30 times the cross-sectional area of the iron leg. It is characterized in that it is formed by being set between.

According to the present invention, with respect to the joint angle between the yoke of the three-phase transformer core and the outer leg, the angle θ _S of the outer leg adjacent to the yoke is defined as tan ^{− 1} (W _L / W
_Y ) [°], the angle θ _Y of the yoke portion in contact with the outer leg portion is 90−θ _S [°], and the joining angle θ _C between the yoke portion and the center leg is 90. Since the three-phase transformer core was configured as °, it was possible to make the magnetic flux density distribution of the yoke uniform.

[0015]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
It will be explained by. 1 and 2, a three-phase transformer core C of the present invention basically includes a pair of outer leg portions 10, 11, a central leg portion 12, and a leg portion 1 as in the prior art.
And yoke portions 13 and 14 disposed above and below 0, 11 and 12, respectively.
3, 14 are leg iron core blanks 10a, 11a, 12a;
Each of the yoke iron core plates 13a and 14a is
The three-phase transformer core C has been configured by shifting the step (step) as one block and connecting it obliquely in a stepwise manner.

In the three-phase transformer iron core C, the width dimension W _Y of the yoke iron core plates 13a and 14a of the yoke portions 13 and 14 is set to be equal to that of the iron leg portions 10, 11 and 12. The width of the plates 10a, 11a, 12a is larger than the width W _L, that is, the cross-sectional area of the yoke portions 13, 14 is changed to the leg iron portion 1.
If the cross-sectional area is larger than 0, 11, 12
When the joining angle of the outer leg portions 10 and 11 to be joined to the leg portions 3 and 14 is, for example, 45 ° as in the related art, the joining cross section on the side of the leg portions 10 and 11 is the yoke portions 13 and 14. As shown in FIG. 12, the notch “a” inevitably becomes larger in the yoke portions 13 and 14 because it is smaller than the joint cross section on the side.

As a result, due to the presence of the notch a, when the magnetic flux moves from the iron legs 10, 11 to the yoke parts 13, 14, the notch a affects the yoke parts 13, 14. Does not flow evenly distributed. Therefore, the magnetic flux is more likely to be concentrated (see FIG. 11) at the center portion in the width direction of the yoke portions 3A and 4A, and in the conventional three-phase transformer core B, the iron loss and the noise are effectively reduced. There was an inherent problem that it was difficult to make it work.

Therefore, in the three-phase transformer core in which the cross-sectional area of the yoke portions 13 and 14 is larger than that of the leg portions 10 and 11, the joint angle between the yoke portions 13 and 14 and the leg portions 10 and 11 is determined. The design had to be made with due consideration of the cross-sectional area ratio.

The most important feature of the present invention is to design and manufacture a three-phase transformer core C in consideration of the above points. That is, in the three-phase transformer core C shown in FIG.
The relationship between the joining angles of the legs 3 and 14 and the iron legs 10 and 11 is set as follows.

First, the yoke portions 13 and 14 and the outer leg iron portions
The joining angles with the layers 10 and 11 are described. Figure 1
And the outer leg iron parts 10, 11 in contact with the yoke parts 13, 14
Joint angle θ of the constituent iron iron core base plates 10a and 11a
_SIs θ_S= Tan^-1(W_L/ W _Y) [°]
To form. Also, the outer legs 10 and 11 are in contact with each other.
Iron core plates 13a constituting the yoke portions 13, 14
14a joining angle θ_YIs 90-θ_SSet by (°)
Formed. Furthermore, the yoke parts 13 and 14 and the center leg 12
Joint angle θ with iron core plate 12a_CIs set to 90 °
Formed.

However, the center leg 12 and the yoke portions 13, 14
Is ideally set by setting θ _C = 2θ _S (this is because the iron legs 10, 11 and the yoke portions 13, 14 and the yoke portions 13, 14 and the central leg 12 are formed). However, in order to make the size of the notch portion generated when they are joined together uniform), in this case, when the yoke core base plates 13a and 14a are processed with the V notch, as described above, , 11,
Depending on the ratio of the sectional area of each of the yoke 12 and the yoke portions 13 and 14, it is necessary to prepare molds having various sizes in advance, so that it becomes very uneconomical and there is no convenience.

Therefore, if the joining angle θ _C between the yoke portions 13 and 14 and the center leg 12 is 90 °, the types of the dies can be limited to some extent, and at least the economic loss due to the dies is good. Can be avoided. In addition, the above point is determined by the magnetic field analysis by the finite element method,
Even if the joint angle between 4 and the center leg 12 is 90 °,
It was confirmed that the magnetic flux density in the yoke portions 13 and 14 can be made uniform.

The joining angle (cutting angle) θ _S of the leg iron core plates 10a, 11a and the yoke iron core plates 13a, 1
The joining angle θ _{Y of} 4a is, for example, θ _S set in advance,
Although the case where the range of -1 ° to + 1 ° is added to each of θ _Y is included, it is sufficient that θ _S + θ _Y = 90 ° as a total.

The iron iron core plate 12a of the center leg 12
Yoke iron core plate 13 to which the convex part b formed at 90 ° is joined
The cutting depth Q of each of a and a is generally calculated as follows. It is preferable to set in the range of W _Y / 2 ≧ Q ≧ W _L / 2. In this case, W _Y
It indicates the width dimension, W _L indicates the width of the leg of section 10, 11 and 12.

As described above, for example, the cut depth Q of the yoke portions 13 and 14 in the three-phase transformer core C shown in FIG.
It is set by W _Y / 2>Q> W _L / 2. In this way, when the cut depths of the yoke portions 13 and 14 are set to form the yoke core base plates 13a and 14a, the three-phase transformer core C shown in FIGS. to be formed with a large cut-out portion P ₁ in the yoke portion 13 and 14 side than 11,12. As described above, each of the iron core portions 10a to 12a and 13a to 14a of the leg iron portions 10 to 12 and the yoke portions 13 to 14 formed by setting the joining angle is made of four pieces as one block. As shown in FIG. 1, the three-phase transformer core C is formed by laminating in a stepwise diagonal manner in four steps.

Next, the yoke section 1 in the three-phase transformer core C
In the present invention, the cross-sectional area of each of the leg irons 10, 11, and 12 is set to 1.0 based on various magnetic field analyzes.
It was confirmed that by setting the value in the range of 1-1.30 times, good results were obtained for the core characteristics.

That is, in the three-phase transformer core C shown in FIG. 1 in which the ratio in the cross-sectional area, the setting of the joining angle, and the setting of the cutting depth are set, for example, the average magnetic flux density of the iron legs is 1.7.
T, when the excitation frequency was set to 60 Hz and the iron loss value was determined by magnetic field analysis, the iron loss value of the conventional three-phase transformer core A was set to 1
00%, the iron loss value of the three-phase transformer core C of the present invention is 93.3%, and the conventional second three-phase transformer core B
, It was found that the iron loss value was further reduced by 2.2%.

Further, when the ratio of the cross-sectional area between the iron leg portion and the yoke portion at which the effect of reducing the iron loss value is obtained is analyzed by the magnetic field analysis to find the optimum value, as shown in the characteristic diagram of FIG. The ratio of the width of the yoke iron core plate to the width of the leg iron core plate is 1.3.
It was found that iron loss was sufficiently reduced up to around zero. As a result, as described above, the cross-sectional area of the yoke portions 13 and 14 is 1.01 to the cross-sectional area of the leg portions 10, 11 and 12.
It was confirmed that if the value was set in the range of ~ 1.30 times, a sufficient effect on iron loss could be obtained.

By forming the three-phase transformer core C shown in FIG. 1 as described above, the conventional magnetic flux density distribution flowing through the yoke portions 13 and 14 was measured. As shown in FIG. Yoke parts 13 and 14 (14 is not shown in FIG. 2)
Although a part of the magnetic flux flowing through the yoke portions 13 and 14 hardly flows near the upper corners (black portions) at both ends, the magnetic flux is substantially uniform over the entire area of the yoke portions 13 and 14 as a whole ( (The white portion), the magnetic flux density distribution is maintained better than in the prior art (see FIG. 10), and iron loss and noise can be effectively reduced.

This is, as shown in FIG.
When the yoke portions 11 and 12 are joined to the yoke portions 13 and 14, the notch portions formed on the yoke portions 13 and 14 side are slightly larger notches in a part of the yoke portions 13 and 14 joined to the center leg 12. Although P ₁ is present, the notch portions are formed on the side of the leg iron portions 10 and 11 so that the notch portions themselves are reduced (resulting from the notch depth Q of the yoke portions 13 and 14). It is considered that the flow of the magnetic flux is hardly hindered by the existence of the magnetic field.

Next, a second embodiment of the present invention will be described with reference to FIGS. The basic configuration of the core itself in the three-phase transformer core D shown in FIG. 3 is the same as that of the three-phase transformer core C shown in FIG. That is, the joint angle between the leg iron parts 10, 11, 12 and the yoke parts 13, 14; the ratio to the cross-sectional area of the leg iron parts 10, 11, 12 and the yoke parts 13, 14; It is about the lamination method (oblique joining) of 12a and the yoke iron core base plates 13a to 14a.

On the other hand, the point different from the three-phase transformer core C is that the cut depth of the yoke iron core plates 13a and 14a of the yoke portions 13 and 14 into which both ends of the iron core plate 12a constituting the center leg 12 are inserted. Q ₁ is different is. The cut depth Q ₁ of the yoke portions 13 and 14 in the three-phase transformer core D in the second embodiment is set to Q ₁ = W _L / 2.

At the above-mentioned cutting depth Q ₁ , the yoke iron core plate 13
a, to form a 14a, as shown in FIGS. 3 and 4, a notch P ₂ generated in the yoke portions 13 and 14, and a notch P ₂ generated by the central leg 12, so that a uniform size The three-phase transformer core D is formed by laminating the leg iron parts 10, 11, 12 and the yoke parts 13, 14.

The iron loss value of the three-phase transformer core D is determined by analyzing the iron loss value by magnetic field analysis, for example, with the average magnetic flux density of the iron leg portion being 1.7 T and the excitation frequency being 60 Hz. Assuming that the iron loss value of the transformer core A is a reference (100%), the iron loss value of the three-phase transformer core D shown in the second embodiment is 93.7%, and the iron loss value of the three-phase transformer core B is 1 than the loss value.
It was found to be reduced by 8%.

The yoke 1 of the three-phase transformer core D
As shown in FIG.
Although there are only three places (black parts) at the upper end in the longitudinal direction of the yoke parts 13 and 14 (not shown in FIG. 4), the yoke parts 13 and 14 It can be seen that it flows uniformly over the entire area (white part in FIG. 4).
As a result, also in the three-phase transformer core D in the second embodiment, the magnetic flux density distribution is better maintained than in the conventional three-phase transformer cores A and B, and the effect of reducing iron loss and noise is improved. It becomes possible. Also in this case, the legs 10,
Joint angle between 11 and 12 and the yoke portion 13, 14, and presumably owes to the presence of cut depth Q ₁ in the yoke portions 13 and 14.

Further, a third embodiment of the present invention will be described with reference to FIGS. The basic configuration of the three-phase transformer core E shown in FIG. 5 is the same as the three-phase transformer cores C and C of the first and second embodiments.
Same as D. Meanwhile, the three-phase transformer core C, differs from the D is the cutting depth Q ₂ of the yoke portions 13 and 14 which the central leg 12 is joined, yoke portion 1 in the third embodiment
The cutting depths Q ₂ of the cuts 3 and 14 are set by Q ₂ = W _Y / 2.

[0037] Then, the depth of cut Q ₂ by yoke core material plates 13a, to form a 14a, as shown in FIGS. 5 and 6, causes the notch P ₃ in the yoke portion 13 and 14 side However, the notch portions 10, 11, 12 and the yoke portion 1 were made so that notches were not so much formed in the leg portions 10, 11.
The three-phase transformer core E is formed by stacking the three-phase transformers 3 and 14.

When the three-phase transformer core E of the third embodiment is analyzed by a magnetic field analysis, for example, when the average magnetic flux density of the iron legs is 1.7 T and the exciting frequency is 60 Hz, the iron loss value is analyzed. If the iron loss value of the three-phase transformer core A is 100%, the three-phase transformer core E is 94.1%,
It was also found that the iron loss value of the three-phase transformer core B was reduced by 1.4%.

As a result, as shown in FIG. 6, the magnetic flux flowing through the three-phase transformer core E is slightly applied to the black portions shown at the upper and lower ends in the longitudinal direction of the yoke portions 13 and 14 (not shown). Despite some difficult-to-flow areas, overall yoke 1
The magnetic flux density distribution is maintained satisfactorily by flowing through the entire portions 3 and 14 (white portions in FIG. 6), and the effect of reducing iron loss and noise can be improved satisfactorily. The present invention is shown in FIGS.
The yoke iron core plates 13a and 14a used for the three-phase transformer cores C, D and E shown by 3 and 5 are all formed by one iron core plate. For example, as shown in FIGS. And the yoke iron core plates 13a ', 13b, 14 formed in two parts.
Needless to say, the three-phase transformer cores F and G may be configured using a ′ and 14b.

[0040]

As described above, according to the present invention,
At the joint angle between the yoke of the three-phase transformer core and the outer leg
The angle θ on the side of the outer leg iron contacting the yoke._S
To θ_S= Tan^-1(W_L/ W_Y) [°], the outer leg
Angle θ of the yoke part in contact with the iron part _YIs 90-θ_S[°] and
And the joint angle θ between the yoke and the center leg_C90
° to constitute the three-phase transformer core
The loss value can be reduced effectively, and the magnetic flux density distribution of the yoke is uniform
Satisfactorily.

In addition, since the iron loss can be reduced well and the magnetic flux density distribution can be made uniform, it is possible to provide a three-phase transformer core with less loss and excellent core characteristics.
As a result, coupled with the reduction of the iron loss value, a large-capacity three-phase transformer core can provide a transformer core having an excellent noise effect, which is convenient.

[Brief description of the drawings]

FIG. 1 is a plan view showing a three-phase transformer core of the present invention.

FIG. 2 is a magnetic flux density distribution diagram in the three-phase transformer core of FIG.

FIG. 3 is a plan view of a three-phase transformer core shown as a second embodiment of the present invention.

FIG. 4 is a magnetic flux density distribution diagram in the three-phase transformer core of FIG. 3;

FIG. 5 is a plan view of a three-phase transformer core shown as a third embodiment of the present invention.

FIG. 6 is a magnetic flux density distribution diagram of the three-phase transformer core shown in FIG.

FIG. 7 is a plan view showing a three-phase transformer core of the present invention using a divided yoke core plate.

FIG. 8 is a plan view showing a three-phase transformer core of the present invention constituted by using another yoke core base plate similarly divided into two.

FIG. 9 is an explanatory diagram showing iron loss characteristics of the three-phase transformer core of the present invention.

FIG. 10 is a plan view showing a conventional three-phase transformer core.

11 is a magnetic flux density distribution diagram of the three-phase transformer core shown in FIG.

FIG. 12 is a plan view of a three-phase transformer core shown as another conventional example.

[Explanation of symbols]

 10, 11, 12 Leg iron part 13, 14 Yoke part 10a, 11a, 12a Leg iron core plate 13a, 14a Yoke iron core plate

Claims (2)

[Claims] 1. An iron core core plate and a yoke iron core plate are laminated in a required number of layers, and a connecting position between the iron core core plate and the yoke iron core plate is shifted stepwise to form an oblique connection. In the three-phase transformer core configured as described above, the cross-sectional area of the yoke section is set to be larger than the cross-sectional area of the yoke section section by making the width dimension W _Y of the yoke core section plate larger than the width dimension W _L of the leg iron core section sheet. The angle θ at both ends in the length direction of the outer leg iron core plate in contact with the yoke iron core plate.
_S is defined as θ _S = tan ⁻¹ (W _L / W _Y ) [°], and the angle θ _Y of the yoke iron core plate in contact with the outer leg iron core plate is expressed as θ _Y =
90-θ _S [°], wherein the angle θ _C between the yoke iron core plate and the center leg iron plate is set to 90 °, a three-phase transformer core. 2. The yoke portion is formed so that its cross-sectional area is set between 1.01 and 1.30 times the cross-sectional area of the leg iron portion. 3. The three-phase transformer core according to 1.