JPH11307368A - Core in three-phase transformer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a core loss, a magnetorestrictive phenomenon caused by core material, and an electromagnetic vibration related to magnetic attractive force. SOLUTION: Leg parts 11 and 12 are made of laminated leg steel core raw plates. In this case, high orientational electromagnetic steel plates with good properties in orientation and integration in a rolling direction at an axis of easy magnetization are laminated. In yoke parts 13 and 14 made of laminated yoke core raw plates, orientational electromagnetic steel plates with a cross section larger than that of the leg steel parts 11 and 12 are laminated. The ratio of cross sections between the leg parts 11 and 12 and the yoke parts 13 and 14 is set preferably in the range from 0.05 to 1.15 fold.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a combination of a leg iron part made of a highly oriented magnetic steel sheet and a yoke part made of a oriented magnetic steel sheet for the purpose of reducing iron loss and noise characteristics. Improved three-phase transformer core.

[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. 5 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 iron leg portions 1, 1 and 2 and the yoke portions 3 and 4 is made of, for example, one of a highly-oriented electrical steel sheet or a grain-oriented electrical steel sheet. In order that the magnetization directions coincide with each other,
The three-phase transformer core A is formed by cutting and joining and laminating the joints between the iron and the yoke parts 3 and 4 so that the magnetic flux can easily pass therethrough.

[0004]

The three-phase transformer core A
, The joints between the iron leg portions 1 and 2 and the yoke portions 3 and 4 are formed by the iron leg core plates 1a, 1b... And the yoke iron core plates 4a and 4
6 are cut at 45 °, and the cut portions are alternately joined and laminated as shown in FIG. 6 (in this case, the leg portions 1, 1 and the yoke portions 3, 4). In this case, the center leg iron part 2 is cut at both ends into a triangular shape, and the yoke part 3,
In Fig. 4, an iron core construction method of joining and laminating at a portion cut into a triangle is adopted. However, in this joining method, iron loss increases or excitation current increases due to a phenomenon of high magnetic flux density at the time of magnetic flux transfer. It was difficult to reduce the noise of the iron core.

[0005] In order to improve the characteristics at the joint, usually, for example, as shown in FIG. 7, a method of joining iron cores composed of leg iron core blanks 1a... And yoke iron core blanks 4a. By stacking and joining a plurality of steps (three or more steps) in a stepwise manner, iron loss and noise have been reduced.

[0006] In the three-phase transformer core A,
When comparing the results of measuring the iron loss and noise characteristics when the excitation frequency is 60 Hz in each joining method (alternate joining, stair joining), in FIGS. In addition, B shows the iron loss and noise characteristics when laminated by stepwise joining, respectively. As can be seen from FIGS. 8 and 9, the iron core laminated by stepwise joining was laminated by alternately joining. For iron cores, both the iron loss and noise characteristics are considered to have a certain reduction effect where the magnetic flux density is low, but conversely, as the magnetic flux density increases, the iron loss and noise effects decrease. There was a problem.

[0007] In view of the above problems, the present invention reduces iron loss and noise as much as possible by reducing the magnetostriction phenomenon caused by the iron core material and the electromagnetic vibration caused by the magnetic attractive force as well as the iron loss. An object of the present invention is to provide a phase transformer core.

[0008]

SUMMARY OF THE INVENTION According to the present invention, a leg iron core plate and a yoke iron core plate are laminated in a required number of layers, and the leg iron core plate and the yoke iron core plate are stepped. In the three-phase transformer iron core formed by obliquely joining the iron core, the iron core portion on which the iron core iron plates are laminated is a highly-oriented electromagnetic member having excellent degree of integration and orientation in the rolling direction of the easy magnetization axis. The yoke portion is formed by stacking steel plates, and the yoke portion for stacking the yoke iron core plate is formed by stacking directional electromagnetic steel sheets having a cross-sectional area of itself larger than the cross-sectional area of the leg iron portion. I do.

In the present invention, a cross-sectional area of the yoke portion;
The cross-sectional area ratio of the leg iron portion is set between 0.05 and 0.15 times.

According to the present invention, the leg iron part uses a high-oriented electrical steel sheet having excellent orientation in the rolling direction, the yoke part uses a grain-oriented electrical steel sheet, and the yoke part uses the same. Since the three-phase transformer core is made of an electromagnetic steel sheet whose cross-sectional area is larger than the cross-sectional area of the iron legs, the magnetic attraction force generated at the joint between the iron core and the iron core and the vibration caused by the magnetostriction of the electromagnetic steel sheet・ It has become possible to suppress noise well.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The basic structure of a three-phase transformer core according to the present invention is to combine the features of the following two measures. That is, as a three-phase transformer core used for a power transformer, a high-oriented electrical steel sheet or a grain-oriented electrical steel sheet is generally used. Since the high-oriented electrical steel sheet has improved orientation in the rolling direction, the magnetic properties against iron loss, magnetostriction, and the like in the rolling direction are improved as compared with the conventional grain-oriented electrical steel sheet, but are shifted from the rolling direction. On the contrary, the magnetic properties in the direction become worse.

As a result, as shown in FIG. 10, for example, as shown in FIG. 10, when the high-oriented electrical steel sheet is used for the three-phase transformer iron core, as compared with the case where the conventional grain-oriented electrical steel sheet is used, the three-phase transformer iron core is used. The flow of the magnetic flux d near the junction a (the top of the central leg 2) between the yoke 3 of A and the central leg 2 is a so-called rotating magnetic flux in which the vector locus of the magnetic flux density rotates. b will occur. In this case, since the magnetic flux d also flows in a direction other than the rolling direction of the magnetic steel sheet, even if the increase in iron loss in other parts can be reduced, the increase in iron loss in the joint a can be ignored. However, in selecting the core material for the three-phase transformer core, it was necessary to take these points into consideration when designing.

In the present invention, in consideration of the above points, as a first measure when designing a three-phase transformer core, for example, as a base iron core plate forming a base iron part in the rolling direction. A highly-oriented electrical steel sheet that uses a highly-oriented electrical steel sheet that has excellent magnetic properties, and has a magnetic property in a direction other than the rolling direction that is superior to that of the highly-oriented electrical steel sheet in the yoke core sheet that forms the yoke portion. use described case where the three-phase transformer core a _1.

In FIG. 5, high-oriented electrical steel sheets are applied to the iron legs ₁ , 2 of the three-phase transformer core A1, and the yoke portions 3, 4 are provided.
Case where the three-phase transformer core A ₁ using each oriented electrical steel sheet (junction leg of portion 1,1,2 and yoke sections 3 and 4, a stepped stacking bonding) to its The results of measuring the iron loss and noise characteristics at an excitation frequency of 60 Hz will be described with reference to FIG. 11 (iron loss characteristics) and FIG. 12 (noise characteristics).

In FIGS. 11 and 12, B shown in FIG.
Shows the iron loss and noise characteristics of the three-phase transformer core A in which the core materials of the leg iron parts 1, 1 and 2 and the yoke parts 3 and 4 are all made of highly oriented magnetic steel sheets. . Meanwhile, C is a three-phase transformer core A ₁ of the iron loss is constituted by said first measure, shows the noise characteristics, the three-phase transformer core A ₁ fabricated by the first strategy in Fig. 11, It can be seen that there is not much difference in iron loss as compared with the conventional three-phase transformer core A.

[0016] Further, in the noise characteristic shown in FIG. 12, the core A ₁ was fabricated by the first approach, the magnetic flux density is 1.
At 6T or less, the noise characteristics are reduced as compared with the conventional iron core, but when the magnetic flux density becomes 1.6T or more, it becomes clear that the magnetic field becomes higher (deteriorated).

On the other hand, the grain-oriented electrical steel sheets used for the yoke portions 3 and 4 of the iron core A ₁ manufactured by the _{first method have} the iron loss and magnetostriction in the rolling direction which are the same as those of the conventional three-phase transformer iron A. The iron loss is about 1.3 times and the magnetostriction amplitude is about 2.3 times compared with the high-oriented electrical steel sheet used for the leg irons 1 to 2 and the yoke 3 and 4. Not much worse than the magnetic properties of the three-phase transformer core A,
It can be evaluated sufficiently.

Next, as a second measure in designing a three-phase transformer core, as shown in FIG. 5, a high-strength core material used for the leg portions 1, 1, 2 and the yoke portions 3, 4 is used. Only one of the oriented magnetic steel sheet and the oriented magnetic steel sheet is used, and the cross-sectional area of the yoke portions 3 and 4 corresponds to the leg iron portion 1.
And larger than the cross-sectional area of 1 is the case constituting the three-phase transformer core A _2. In this case, that is,
And the yoke portions 3 and 4 are connected in a stepwise manner. It is generally considered that if the cross-sectional area of the yoke is larger than the cross-sectional area of the iron leg, the average magnetic flux density in the yoke can be lower than the average magnetic flux density of the iron leg.

The iron loss and noise characteristics of the three-phase transformer core A ₂ manufactured by the above-mentioned second measure are measured by setting the excitation frequency to 60 Hz.
The results of the measurement will be described with reference to FIG. 13 (iron loss characteristics) and FIG. 14 (noise characteristics). In FIGS. 13 and 14, B denotes a conventional three-phase transformer core (the irons 1, 2, and the yokes 3, 4 described in the case of the first measure are similarly highly oriented electromagnetic). A made of steel plate) shows A, E shows the second
Three-phase transformer core A ₂ of the core fabricated by measures, indicating the noise characteristics.

[0020] Then, as far as the data of FIG. 13 and 14, the iron loss and noise characteristics of the iron core A ₂ fabricated by the second strategy, as also the magnetic flux density Izure is sequentially increased, the conventional three-phase transformer It is well found that the iron core A is smaller than the iron core A. This is because the cross-sectional area of the yoke parts 3 and 4 is larger than that of the iron iron parts 1 and 1 and 2. This is considered to be because the magnetic flux flowing from the yoke portions 3 and 4 from the yoke portions 3 and 4 can be satisfactorily mitigated from being concentrated in the yoke portions 3 and 4.

According to the present invention, the iron loss and noise characteristics are further improved by effectively utilizing the features obtained by the three-phase transformer cores A ₁ and A ₂ configured by the first and second measures. An object of the present invention is to provide a phase transformer core.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. According to the present invention, in order to realize the above object, in FIG. 1, 11 and 11 indicate leg portions of a three-phase transformer core B, 12 indicates a center leg portion, and each of these leg portions 11 , 11, and 12 are formed by laminating required layers of leg iron core plates made of highly oriented magnetic steel sheets. In FIG. 1, reference numerals 13 and 14 denote yoke portions, which are formed by laminating required layers of yoke core base plates made of grain-oriented electrical steel sheets. And
The iron leg portions 11, 11, 12 and the yoke portions 13, 14 are stair-stacked and joined to form a three-phase transformer core A _3.
To form

Further, in the present invention, the three-phase transformer core A
_The cross-sectional area S of each of the legs 11, 11, 12 forming
The ratio of ₁ (see FIG. 2A) to each cross-sectional area S ₂ of the yoke portions 13 and 14 (see FIG. 2B) is S ₂ = 1.050.
It was ~1.150S _1. That is, 1.050 to 1.150 times the cross-sectional area S ₂ of the yoke portions 13 and 14 with respect to the cross-sectional area S ₁ of the leg of portion 11,11,12, the present invention is a three-phase transformer core A ₃ Was configured.

The three-phase transformer core A _{3 of the} present invention and FIG.
3 and 4 show the results of measuring the iron loss and noise characteristics of the conventional three-phase transformer core A shown in FIG. The measurement results in FIGS. 3 and 4 are obtained when the excitation frequency is measured at 60 Hz. In FIG. 3, 4, F indicates the iron loss and noise characteristics of the three-phase transformer core A ₃ which was prepared in the present invention, B is iron loss and noise in the conventional three-phase transformer core A shown in FIG. 5 It is a characteristic.

First, at the iron loss, it becomes clear that the three-phase transformer core A ₃ of the present invention has a lower magnetic flux density than the conventional three-phase transformer core A, ie, in FIG. , if the magnetic flux density was iron loss and (B) 100% of the conventional core a at the level of 1.7 T, the iron loss in the core a ₃ of the present invention (F) is reduced to approximately 5% decrease to 95% It turned out to be.

[0026] Also in the noise characteristics, in a three-phase transformer core A ₃ of the present invention, throughout the range of the measured magnetic flux density, it can be seen that the noise in comparison with the conventional iron core A is greatly reduced. By comparison, comparing the noise of the present invention with that of the conventional iron core, it can be seen in FIG. 4 that the magnetic flux density is reduced by about 4.2 dB at the level of 1.5T and about 4.6 dB at the level of 1.7T. found. That is, the three-phase transformer core A ₃ produced in the core structure of the present invention has a greatly as in the iron loss characteristics in the noise characteristics, and it has become possible to satisfactorily reduced.

[0027] The three-phase transformer core A ₃ of the present invention, configuration leg of portion 11,11,12 of the core material, while increasing orientation in the rolling direction, the magnetic properties are reversed in the other direction In contrast, the yoke portions 13 and 14 have a magnetic property in a direction other than the rolling direction. since so as to produce a phase transformer core a _3, when excited the three-phase transformer core a _3, leg of portions 11,11,12 and yoke parts 13 and 14,
Each is formed so that magnetic flux can flow easily.

That is, the three-phase transformer core A ₃ of the present invention uses a grain-oriented electrical steel sheet having a better magnetic flux flow than the high-oriented electrical steel sheet in the yoke portions 13 and 14 in directions other than the rolling direction. Magnetic flux moves to the yoke parts 13 and 14 (inflow)
In doing so, it does not concentrate on a specific portion of the yoke portions 13 and 14. Further, the yoke portions 13 and 14 have a cross-sectional area S _2.
(Width dimension) is larger than the cross-sectional area S1 of the leg portions 11, 11, 12, so that the leg portions 11, ₁ are used.
When magnetic flux flows into the yoke parts 13 and 14 from
Since the magnetic flux does not concentrate on the yoke portions 13 and 14 and flows in a relaxed state by effectively using the wide yoke portions 13 and 14, as described above, the iron loss and noise characteristics are reduced. Can be satisfactorily improved. In the present invention, the cross-sectional area of the yoke is 1.05
Although described in the example set to 1.15 times, the ratio of the cross-sectional area of the yoke part and the leg iron part is set to 0.05 to 0.15 times without limiting to this. The present invention is established even if it is formed by using the above method.

[0029]

According to the present invention, as described above, vibration and noise due to magnetostriction of an electromagnetic steel sheet due to iron loss of a transformer core and magnetic attraction can be satisfactorily suppressed.
As a result, quality improvement such as energy saving can be achieved, and noise countermeasures such as soundproof walls and sound insulation walls surrounding the transformer can be simply and economically manufactured.

[Brief description of the drawings]

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

2 (a) shows a cross section taken along line XX of FIG. 1, and FIG. 2 (b) shows a cross section taken along line YY of FIG.

FIG. 3 is an explanatory diagram comparing iron loss characteristics between a three-phase transformer core of the present invention and a conventional three-phase transformer core.

FIG. 4 is an explanatory diagram comparing noise characteristics of a three-phase transformer core of the present invention and a conventional three-phase transformer core.

FIG. 5 is a plan view showing a conventional three-phase transformer core and a three-phase transformer core formed by the first and second measures;

FIG. 6 is a cross-sectional view of a main part showing a state of alternate stacking and joining in a conventional three-phase transformer core.

FIG. 7 is a cross-sectional view of a principal part showing a state of step-wise joining in a conventional three-phase transformer core.

FIG. 8 is an iron loss characteristic diagram of a conventional three-phase transformer core.

FIG. 9 is a noise characteristic diagram of a conventional three-phase transformer core.

FIG. 10 is an explanatory diagram showing a distribution of a rotating magnetic flux at a joint portion between a leg iron portion and a yoke portion at the center of a three-phase transformer iron core.

FIG. 11 is an explanatory diagram comparing iron loss characteristics between a three-phase transformer core formed by the first measure and a conventional three-phase transformer core.

FIG. 12 is an explanatory diagram similarly comparing noise characteristics.

FIG. 13 is an explanatory diagram comparing iron loss characteristics between a three-phase transformer core formed by the second measure and a conventional three-phase transformer core.

FIG. 14 is an explanatory diagram similarly comparing noise characteristics.

[Explanation of symbols]

11,12 sectional area of the cross-sectional area S ₂ yoke portion of the leg of section 13, 14 yoke portion S ₁ leg of section

Claims (2)

[Claims] 1. A structure in which a required number of layers of a leg iron core plate and a yoke core core plate are laminated, and the leg iron core plate and the yoke core core plate are obliquely joined by being shifted stepwise. In the three-phase transformer iron core, the iron leg portion for laminating the iron leg core plate is formed by laminating high-oriented electrical steel sheets having an excellent degree of integration and orientation in the rolling direction of the easy magnetization axis, and a yoke iron core. A three-phase transformer core, wherein the yoke portion for laminating the base plates is formed by laminating directional electromagnetic steel sheets whose cross-sectional area is larger than the cross-sectional area of the leg iron portion. 2. The method according to claim 1, wherein the ratio between the cross-sectional area of the yoke and the cross-sectional area of the leg iron is set to a value between 0.05 and 1.15. Three-phase transformer core.