JP2009231477A - Manufacturing method of transformer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a transformer, using a grain-oriented electromagnetic steel plate, in which a transformer of low noise, with less variations in noise, is stably obtained. <P>SOLUTION: This method is for manufacturing a transformer, comprising an iron core which includes a grain-oriented electromagnetic steel plate. An AC magnetostrictive parameter λ<SB>b</SB>for the grain-oriented electromagnetic steel plate used for the iron core which is defined in formula; λ<SB>b</SB>=max(λ<SB>P-P15/50</SB>, λ<SB>P-P16/50</SB>, λ<SB>P-P17/50</SB>, λ<SB>P-P18/50</SB>)+λ<SB>0-P19/50</SB>(a magnetostriction 0-peak value in 50 Hz-1.7T, for example, is represented as λ<SB>0-P17/50</SB>, and peak-peak value in 50 Hz-1.7T is represented as λ<SB>P-P17/50</SB>), is 1.91×10<SP>-6</SP>or smaller. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a transformer, and more particularly to a method for manufacturing a transformer with low noise using a grain-oriented electrical steel sheet.

  As the transformer (transformer), it is common to use a laminate of grain-oriented electrical steel sheets (stacked iron core) or a wound one (rolled iron core). Important characteristics required for the transformer include excellent iron loss (no load loss) characteristics and exciting current characteristics. Furthermore, in recent years, it has become important to have excellent noise characteristics, that is, low noise, in consideration of the surrounding environment where the transformer is installed.

It is known that the noise of a transformer greatly depends on the magnetostriction characteristics of an electromagnetic steel sheet used for an iron core. In addition, the magnetostriction characteristic of the grain-oriented electrical steel sheet is determined by the magnetic flux density B ₈ (magnetic flux density at a magnetic field strength of 800 A / m) that the steel sheet has, and the higher B ₈ is, the magnetostriction (also referred to as magnetostriction). Is known to be small (see Non-Patent Document 1, for example). Therefore, in order to manufacture a low-noise transformer, it is common to use a grain-oriented electrical steel sheet having a small magnetostriction for the iron core.
IEEE Transactions 8 (1972) p. 677

Meanwhile, by using the high-oriented electrical steel sheet having a magnetic flux density B _8, if you produce a plurality of transformers, the noise value of the transformer, as compared with the case of producing using a low oriented electrical steel sheets B ₈ If you look at the average value, you can get a low one. However, looking at the noise level of the individual transformers, B ₈ is despite the use of a grain-oriented electrical steel sheet of the same level, there may be a significant variation observed in the noise level.

  Conventionally, such variations have been unavoidable to some extent. However, this variation is becoming unacceptable in an environment-oriented society in recent years.

  Accordingly, an object of the present invention is to propose a method of manufacturing a transformer that can stably obtain a transformer with low noise and small noise variation in a method of manufacturing a transformer using grain-oriented electrical steel sheets. .

The inventors have found that the above-mentioned problems of the prior art, that is, the noise characteristics of the manufactured transformers show considerable variation despite the fact that B ₈ uses directional electrical steel sheets of the same level. We studied repeatedly to find out the cause of the point. As a result, the factors affecting oriented electrical steel sheet by the noise characteristics of the transformer, in addition to the magnetic flux density B ₈ known from the prior art, there are harmonic components of magnetostrictive noise larger the harmonic components larger, and, in order to reduce the harmonic components of the magnetostriction, it is necessary to control the AC magnetostriction parameter lambda _b that inventors have newly found the proper range, i.e., stable and low-noise transformer to produce Te is found that is possible to use a grain-oriented electrical steel sheet having a controlled AC magnetostriction parameter lambda _b within a proper range is important, and completed the present invention.

That is, this invention is a manufacturing method of the transformer which has an iron core which consists of grain-oriented electrical steel sheets, Comprising: As a grain-oriented electrical steel sheet used for the iron core, following formula | equation;
[lambda] _b = max ([lambda] _{P-P15 / 50} , [lambda] _{P-P16 / 50} , [lambda] _{P-P17 / 50} , [lambda] _{P-P18 / 50} ) + [lambda] _{0-P19 / 50}
Here, in the above formula, for example, the magnetostriction 0-peak value at ₅₀ Hz-1.7 T is expressed as λ _{0-P17 / 50} , and the peak-peak value at ₅₀ Hz-1.7 T is expressed as λ _{P-P17 / 50.} .
A transformer manufacturing method characterized in that an AC magnetostriction parameter λ _b defined by the following is used: 1.91 × 10 ⁻⁶ or less.

Moreover, this invention is a manufacturing method of the transformer which has an iron core which consists of a grain-oriented electrical steel sheet, Comprising: As a grain-oriented electrical steel sheet used for the iron core, following formula | equation;
[lambda] _b = max ([lambda] _{P-P15 / 50} , [lambda] _{P-P16 / 50} , [lambda] _{P-P17 / 50} , [lambda] _{P-P18 / 50} ) + [lambda] _{0-P19 / 50}
Here, in the above formula, for example, the magnetostriction 0-peak value at ₅₀ Hz-1.7 T is expressed as λ _{0-P17 / 50} , and the peak-peak value at ₅₀ Hz-1.7 T is expressed as λ _{P-P17 / 50.} .
The transformer is characterized in that the AC magnetostriction parameter λ _b defined in (1) is less than or equal to the maximum value of λ _b determined from the variation in the noise value allowed for the transformer to be manufactured or within the range between the maximum value and the minimum value. It is a manufacturing method.

  In the present invention, the iron core is a stacked iron core or a wound iron core.

According to the present invention, since the iron core is manufactured using only the directional electrical steel sheet selected using the parameter (AC magnetostriction parameter λ _b ) that can accurately predict the actual machine noise performance of the transformer, a plurality of transformers of the same design are used. Even when a stand is manufactured, it is possible to stably manufacture a transformer with low noise and small variation in noise value.

The noise performance of a transformer using a grain-oriented electrical steel sheet as an iron core depends on the magnetostriction characteristics of the grain-oriented electrical steel sheet, and the magnetostriction characteristics of the grain-oriented electrical steel sheet depend on the magnetic flux density B ₈ (magnetic field strength 800A). Magnetic flux density at / m). Therefore, the noise characteristics of the transformer has been substantially determined by a magnetic flux density B ₈ of steel sheets used for the core. However, even though B ₈ levels with approximately equal oriented electrical steel sheet, the manufacturing time and manufacturing rods are different, the noise characteristics of the transformer phenomenon different were frequently observed.

Inventors prepared a plurality of grain-oriented electrical steel sheets with different production times and production rods to elucidate the cause of the variation, investigated the magnetostriction characteristics of the materials in detail, manufactured a model transformer, and the relationship with the noise characteristics. investigated. As a result, even approximately equal oriented electrical steel sheet B ₈ levels, the difference in the magnetostrictive harmonic component by the production time and production rod is observed, the corresponding and the difference between the difference and the transformer noise characteristics of the harmonic components I found out.

  Magnetostriction is caused by a change in the shape (dimension) of the magnetic steel sheet when the magnetic flux density of the magnetic steel sheet changes, but the relationship between the change in magnetic flux density and the shape change is generally non-linear. Therefore, even if AC excitation is performed with a sine waveform and the change in magnetic flux density is a sine wave, the magnetostrictive waveform is distorted. This waveform is composed of a fundamental wave component having a frequency twice the voltage frequency of the connected electrical system and a harmonic component having a frequency that is an integer multiple of the fundamental wave component. Then, when the latter harmonic component is propagated to the air, it is perceived by a person as an unpleasant sound and raises the noise level.

  Therefore, in order to produce a low noise transformer, the magnetostrictive harmonic component of the grain-oriented electrical steel sheet used for the iron core is measured in advance, and the steel sheet to be used is selected based on the level of the harmonic component. A noise transformer can be manufactured. However, in order to use the magnetostrictive harmonic component for production management of an actual machine, it is not preferable because the measurement of the magnetostrictive harmonic component is extremely time-consuming and requires a new equipment investment for the measurement.

Therefore, the inventors have further investigated whether it is possible to predict the magnetostrictive harmonic component from the magnetostriction characteristics (the magnetostriction 0-peak value and the peak-peak value) conventionally used for production management of actual machines. As a result, for example, the magnetostriction 0-peak value (difference between the magnetostriction and the maximum magnetostriction when the magnetic flux density is 0) at 50 Hz-1.7 T is λ _{0-P17 / 50} , and the peak-peak value (the maximum magnetostriction and the minimum magnetostriction). When the difference is expressed as λ _{P-P17 / 50} ,
[lambda] _b = max ([lambda] _{P-P15 / 50} , [lambda] _{P-P16 / 50} , [lambda] _{P-P17 / 50} , [lambda] _{P-P18 / 50} ) + [lambda] _{0-P19 / 50}
It was found that there is a very strong correlation between the AC magnetostriction parameter λb defined by ₍₁₎ and the magnetostrictive harmonic characteristics. Here, max (λ _{P-P15 / 50} , λ _{P-P16 / 50} , λ _{P-P17 / 50} , λ _{P-P18 / 50} ) is λ _{P-P15 / 50} , λ _{P-P16 / 50} , λ _It means the maximum magnetostriction value in _{P-P17 / 50} and λ _{P-P18 / 50} .

As described above, the reason why there is a correlation between the AC magnetostrictive parameter λ _b and the magnetostrictive harmonic characteristics is not necessarily fully understood, but the λ _b is a magnetic domain structure of a grain-oriented electrical steel sheet, In particular, this is considered to be a good parameter representing the abundance of the 90-degree magnetic domain that is the cause of magnetostriction.

Therefore, the inventors set the noise reduction target of the transformer as a noise value measured at a position 30 cm away from the iron core surface when the iron core is excited at 50 Hz-1.75 T. In order to achieve the above, the AC magnetostriction parameter λ _b that the grain-oriented electrical steel sheet that is the material of the iron core should have was investigated. As a result, the above noise target can be achieved by selecting a grain oriented electrical steel sheet satisfying the relationship of λ _b ≦ 1.91 × 10 ⁻⁶ and manufacturing the iron core, and further, λ _b ≦ 1.71 × 10 ^−6. It was found that a transformer with lower noise can be manufactured if the following relationship is satisfied.

Moreover, lambda even if they do not meet the _b ≦ 1.91 × 10 ^-6 the relationship, define the upper limit of the allowable range of lambda _b in accordance with the noise value allowed to the transformer to produce, lambda _b is If only the grain-oriented electrical steel sheets within the permissible range are selected and the iron core is manufactured, it is possible to reduce the variation in noise characteristics even when manufacturing a plurality of transformers with the same design. I understood it. If necessary, it may be provided lower limit not only the upper limit of the allowable range of lambda _b is a matter of course.

As shown in Table 1, 11 types of steel A~K value of the magnetic flux density B ₈ selected from the oriented electrical steel sheet manufacturing time and manufacturing rods have different plate thickness 0.3mm is approximately equal to (coil ) Were prepared, slitted to a width of 150 mm, and then a bevel cut and V-notch cut were performed to produce a three-phase, three-leg model transformer. The model transformer had a leg and yoke with a width of 150 mm, an outer dimension of 100 sheets of 750 mm × 750 mm, and a V-notch and a step wrap (2 by 6).

In addition, ten single plates each having a width of 100 mm and a length of 400 mm were sampled from each of the 150 mm-width slit coils, and the peak of AC magnetostriction at 50 Hz-1.5T, 1.6T, 1.7T, and 1.8T was obtained. -Peak value (λ _{P-P15 / 50} , λ _{P-P16 / 50} , λ _{P-P17 / 50} , λ _{P-P18 / 50} ) and 0-peak value of AC magnetostriction at 50 Hz-1.9T (λ _{0- P19 / 50} ) and the following formula:
[lambda] _b = max ([lambda] _{P-P15 / 50} , [lambda] _{P-P16 / 50} , [lambda] _{P-P17 / 50} , [lambda] _{P-P18 / 50} ) + [lambda] _{0-P19 / 50}
From calculates the AC magnetostriction parameter lambda _b, to obtain an average value of 10 sheets, respectively.

  Moreover, the noise value (A scale) in 50Hz-1.75T was measured for the noise characteristic of the produced three-phase / three-leg model transformer at a position 30 cm away from the center leg center of the transformer.

The measurement results of the AC magnetostriction parameter lambda _b and trans noise values with are shown in Table 1, and the results are shown in FIGS. FIG. 1 shows that the noise value of the transformer depends on the magnetic flux density B ₈ , but the noise value varies even at the same B ₈ level. Further, from FIG. 2, the transformer noise value has a good correlation with the AC magnetostriction parameter λ _b, and if an iron core is made using a grain oriented electrical steel sheet that satisfies the condition of λ _b ≦ 1.91 × 10 ⁻⁶ , 54 dBA The following low noise transformers can be manufactured. In particular, when a grain-oriented electrical steel sheet having λ _b ≦ 1.71 × 10 ⁻⁶ is used, it is possible to manufacture a very low noise transformer of 52 dBA or less. I understand that I can do it.

Using the steel plates G to K in Table 1, ten three-phase, three-leg model transformers were produced from each steel plate in the same manner as in Example 1, and the noise level of the transformer was determined in the same manner as in Example 1. The noise value variation (maximum value-minimum value) of 10 transformers was obtained. At the same time, a sample was taken from the steel plate used for each model transformer, and the peak-peak value of AC magnetostriction at 50 Hz-1.5T, 1.6T, 1.7T and 1.8T was obtained in the same manner as in Example 1. (Λ _{P-P15 / 50} , λ _{P-P16 / 50} , λ _{P-P17 / 50} , λ _{P-P18 / 50} ) and 0-peak value (λ _{0-P17 / 50} ) of AC magnetostriction at 50 Hz-1.9T. ) Was measured, the AC magnetostriction parameter λ _b was calculated, and the variation (maximum value−minimum value) of λ _b of each steel sheet was obtained.

The measurement results are shown in Table 2. From Table 2, even when the transformer is manufactured using a steel sheet that does not satisfy the condition of λ _b ≦ 1.91 × 10 ⁻⁶ , the transformer can be reduced by suppressing variations in the AC magnetostriction parameter λ _b of the steel sheet. of can reduce variations in noise characteristics, for example, be manufactured transformer AC magnetostriction parameter lambda _b select steel ranging from ± 0.05 × 10 ^-6, the target of the dispersion of the noise ± 1.5DBA less It can be seen that this can be achieved.

The magnetic flux density B ₈ is a graph showing the effect on the transformer noise. It is a graph which shows the influence which AC magnetostriction parameter (lambda) _{b of a} steel plate has on the noise of a transformer.

Claims (3)

A method of manufacturing a transformer having an iron core made of grain-oriented electrical steel sheets, wherein an AC magnetostriction parameter λ _b defined by the following formula is 1.91 × 10 ⁻⁶ or less as a grain-oriented magnetic steel sheet used for the iron core. A method of manufacturing a transformer, characterized by being used.
Λ _b = max (λ _{P-P15 / 50} , λ _{P-P16 / 50} , λ _{P-P17 / 50} , λ _{P-P18 / 50} ) + λ _{0-P19 / 50}
Here, in the above formula, for example, the magnetostriction 0-peak value at ₅₀ Hz-1.7 T is expressed as λ _{0-P17 / 50} , and the peak-peak value at ₅₀ Hz-1.7 T is expressed as λ _{P-P17 / 50.} . A method of manufacturing a transformer having an iron core made of grain-oriented electrical steel sheets, wherein the magnetostrictive parameter λ _b defined by the following equation is a noise value allowed for the transformer to be produced as a grain-oriented magnetic steel sheet used for the iron core. the method of manufacturing a transformer, which comprises using those within the maximum value or less or the maximum and minimum values of lambda _b defined by the variation.
Λ _b = max (λ _{P-P15 / 50} , λ _{P-P16 / 50} , λ _{P-P17 / 50} , λ _{P-P18 / 50} ) + λ _{0-P19 / 50}
Here, in the above formula, for example, the magnetostriction 0-peak value at ₅₀ Hz-1.7 T is expressed as λ _{0-P17 / 50} , and the peak-peak value at ₅₀ Hz-1.7 T is expressed as λ _{P-P17 / 50.} . 3. The method of manufacturing a transformer according to claim 1, wherein the iron core is a stacked iron core or a wound iron core.

Images