JPH0562839A - Transformer core - Google Patents

Abstract

(57) [Summary] [Structure] An iron core made of 3% grain-oriented silicon steel sheet 5 is installed in the central portion in the stacking direction, and 6.5% silicon steel sheet 6 is provided on both sides thereof.
While arranging the iron core consisting of to form the combined iron core 4,
The sectional area ratio of the iron core of the 6.5% silicon steel plate in the leg portion 7 is configured to be larger than the sectional area ratio of the iron core of the 6.5% silicon steel plate in the yoke portion 8. [Effect] Most of the fundamental wave components of 50 Hz and 60 Hz are received by the grain-oriented silicon steel plate 5, and the harmonic components are 6.5%.
The silicon steel plate 6 serves as an iron core, and the proportion of the harmonic components of the main magnetic flux due to the leakage flux of the harmonics in the legs 7 is reduced, eliminating the imbalance between the magnetic flux waveforms of the yoke 8 and the legs 7. As a result, noise can be significantly reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transformer core for use in a transformer for an inverter power supply, a transformer for a rectifier, etc., which has low loss and low noise characteristics.

[0002]

2. Description of the Related Art Recent advances in electronics technology have significantly increased the use of devices using inverter power supplies, such as UPS power supplies.

This type of inverter power supply transformer generally has a fundamental wave component of 50 to 60 Hz, but since the switching element contains harmonics of several kHz to several tens of kHz, the noise of the equipment becomes a problem. .. Conventionally, a transformer for an inverter power supply has been constructed by cutting a grain-oriented silicon steel plate at 45 ° to join a yoke portion and legs and winding a coil 3 around each leg as shown in FIG. .. However, in a laminated iron core transformer using a directional silicon steel plate, the magnetostriction of the directional silicon steel plate is as large as about 2 × 10 ^-6 in the used magnetic flux density region, and noise is increased due to harmonics due to the switching frequency of the inverter. was there. In particular, recently, since there is a tendency to install a UPS power supply in a room, there is an increasing demand for noise reduction.

On the other hand, instead of the conventional 3% grain-oriented silicon steel sheet, a 6.5% silicon steel sheet having a small magnetostriction and excellent characteristics can be used for an iron core used in an induction device such as a transformer. Is being considered. It has long been known that this 6.5% silicon steel sheet has almost zero magnetostriction and less iron loss, but it is considered to be difficult to manufacture by rolling because it becomes brittle as the content of silicon increases. Was there.
However, recently, improvement of rolling technology for brittle materials and CVD
With the progress of the method (chemical vapor deposition method), this kind of 6.5% silicon steel sheet has been developed and put into practical use.
Since the 6.5% silicon steel sheet has a magnetostriction of about 0.2 × 10 ^−6, it is an advantageous material for reducing the noise of the transformer.

[0005]

[Problems to be Solved by the Invention] However, 6.5
% Silicon steel sheet has a poor B-H characteristic in a high magnetic flux density region, so that it has a drawback that an exciting current increases in a device used at a commercial frequency. In addition, there is also one in which the BH characteristic in the high magnetic flux density region is improved by manufacturing a 6.5% silicon steel sheet with a lower annealing temperature, but in this case, there is a problem that iron loss increases. is there. For this reason, a commercial frequency transformer is 6.5
Even if a% silicon steel sheet is used, it is necessary to design the magnetic flux density lower than that of a conventional grain-oriented silicon steel sheet containing 3% silicon, which has been a bottleneck for downsizing and weight reduction of equipment.

On the other hand, when comparing the distortion rates of the iron core yoke section and the leg section under harmonic load, it is usual that the leg section is larger. According to the inventor's experiment, the result obtained by the leg portion was about 5% larger. It is considered that this is because the load current flowing through the coil 3 becomes a distorted wave, and a leakage magnetic flux containing a harmonic is generated, so that the main magnetic flux of the iron core leg contains a harmonic component. For this reason, the distortion rate of the magnetic flux waveform is unbalanced between the iron core yoke and the legs, which further increases the noise.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a transformer core which is suitable for an inverter power supply and which can be constructed with low noise without deteriorating magnetic characteristics. To do.

[0008]

In the transformer core according to the present invention, an iron core made of a 3% grain oriented silicon steel plate is installed in the central portion in the thickness direction and, for example, a 6.5% silicon steel sheet is provided on both sides thereof. A combination of cores made of low magnetostrictive material such as that described above is used, and the cross-sectional area ratio of the core of the low magnetostrictive material in the legs is made larger than the cross-sectional area ratio of the core of the low magnetostrictive material in the yoke part. Is characterized by.

[0009]

When such a laminated iron core is applied to, for example, a transformer for an inverter power source, most of the magnetic flux components of 50 Hz and 60 Hz, which are fundamental wave components, flow to the grain-oriented silicon steel sheet having high permeability in this frequency range. , 2-1 by switching
Most of the 0 kHz harmonic component flows in the 6.5% silicon steel sheet having a high magnetic permeability in this frequency range. FIG. 3 and FIG. 4 show characteristics comparison of the core loss and the exciting capacity of the iron core using a 6.5% silicon steel sheet as the low magnetostrictive magnetic material.

As is clear from this figure, the frequency is 50H.
At z, both the iron loss and the exciting capacity are worse for the 6.5% silicon steel sheet iron core, and especially the exciting capacity is sharply deteriorated from the region where the magnetic flux density exceeds 1.0T. However, as the frequency increases, the difference in the characteristics becomes smaller, and at 400 Hz, both iron cores have almost the same characteristics, and at higher frequencies, the 6.5% silicon steel sheet shows better characteristics in terms of core loss and excitation capacity. Shows. This is because the 6.5% silicon steel sheet has a larger specific resistance than the grain-oriented silicon steel sheet, so that the eddy current loss decreases and the magnetic permeability also increases at high frequencies. The combined characteristics of both iron cores show almost the average characteristics of the respective iron cores.

On the other hand, the noise characteristic is 6.5 as shown in FIG.
% The silicon steel sheet iron core is reduced in the entire frequency range compared to the grain-oriented silicon steel sheet, and the noise values of the two iron cores have a larger difference as the frequency increases.

That is, for example, in a transformer for an inverter power source, since the magnetic flux waveform has a fundamental wave of 50 Hz or 60 Hz and a harmonic of several kHz, most of the fundamental wave component is received by a grain-oriented silicon steel plate, Harmonic component 6.5%
An iron core structure that can be received by a low magnetostrictive magnetic material such as a silicon steel plate, and the cross-sectional area ratio of the iron core of the low magnetostrictive material in the legs is larger than the cross-sectional area ratio of the iron core of the low magnetostrictive material in the yoke part. As a result, the ratio of the harmonic component of the main magnetic flux of the leg portion due to the leakage magnetic flux of the harmonic is reduced, and it is possible to suppress deterioration of the magnetic characteristics and significantly reduce noise.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS.

In the figure, the grain-oriented silicon steel plate 5 is set at 45 °.
The frame-shaped iron cores cut and laminated are arranged at the central portion in the laminating direction, and 6.5% silicon steel plates 6 which are low magnetostrictive magnetic materials are cut on both sides thereof in the same manner as the grain-oriented silicon steel plates 5, The laminated iron cores are integrated to form the iron core 4. In this case, the iron core of the 6.5% silicon steel plate 6 arranged on both sides of the yoke portion 8 of the combined iron core 4 is 30% of the total cross-sectional area of the yoke portion 8 and the 6.5% silicon of the leg portion 7 is The iron core of the raw steel plate 6 is 35 to 45% of the total cross-sectional area of the leg portion 7. That is, the cross-sectional area ratio of the iron core of the 6.5% silicon steel plate 6 in the leg portion 7 is set to the 6.5% silicon steel plate 6 in the yoke portion 8.
5 to 15% larger than the cross-sectional area ratio of the iron core, and the 5 to 15% portion has a grain-oriented silicon steel plate 5 in the yoke portion 8 and a 6.5% silicon steel plate in the legs 7. It is configured by abutting with each other. As shown in FIG. 2, the coil 10 is inserted and attached to the leg portion 7 of the combined iron core 4 to form the transformer 10.

In the transformer core having such a structure, the grain-oriented silicon steel plate 5 is used at a ratio of more than half (55 to 65%) with respect to the total sectional area of the combined core 4,
It is possible to improve the deterioration of the B-H characteristics in the high magnetic flux density region at the commercial frequency, which is a drawback of the 6.5% silicon steel sheet 6, and the iron loss is better than the iron core of the 6.5% silicon steel sheet alone. Become. This is a combination iron core 4,
This is because most of the magnetic flux flows through the grain-oriented silicon steel sheet 5 having a high magnetic permeability in the commercial frequency range.

Regarding the harmonic component (about 2 to 5 kHz) due to the switching frequency of the inverter, most of the magnetic flux component flows in the 6.5% silicon steel plate 6 having high magnetic permeability in the harmonic region, It has excellent magnetic properties as a transformer for inverter power supply.

Regarding noise, the increase in noise due to high frequency becomes a problem, but the magnetostriction of the 6.5% silicon steel plate 6 is about 0.
2 × 10 ^−6, which is about 2 × 1 of grain-oriented silicon steel plate 5.
Against 0 ^-6, since very a degree 1/10 smaller, there is a noise reduction effect.

On the other hand, since the cross-sectional area ratio of the 6.5% silicon steel plate 6 in the leg portion 7 is set to be 5 to 15% larger than that in the yoke portion 8, the leakage of harmonics in the leg portion 7 occurs. The proportion of harmonic components of the main magnetic flux due to the magnetic flux is reduced. In other words, the distortion rate of the magnetic flux waveform in the leg 7 becomes small,
The unbalance of the distortion rates of the magnetic flux waveforms of the yoke portion 8 and the leg portions 7 is eliminated, and the noise can be further reduced.

The difference (5 to 15%) in the cross-sectional area ratio between the 6.5% silicon steel plate 6 in the yoke portion 8 and the leg portion 7 depends on the strain rate of the magnetic flux waveform and the BH characteristics of both core materials. It was selected from the difference of.

In the above embodiment, the laminated cores of the 6.5% silicon steel plate 6 are installed on both sides of the laminated core of the grain-oriented silicon steel plate 5. This is a laminated core having a large radiation surface for noise generation. This is because the noise reduction effect can be further increased by arranging the iron cores of the 6.5% silicon steel plate 6 having a small magnetostriction on both sides in the direction.

The iron core structure is not limited to the inverter power source, but may be used for a rectifier transformer, a fundamental wave (50 Hz or 6 Hz).
Of course, it is effective for equipment in which harmonics are superimposed on 0 Hz). Further, although the single-phase transformer has been described in this embodiment, a three-phase transformer may be used.

[0022]

As described above, according to the transformer core according to the present invention, the combined core of the grain-oriented silicon steel sheet and the 6.5% silicon steel sheet is used and the leg portion is 6.5%.
Cross-sectional area ratio of silicon steel sheet is 5 to 15% than that of yoke part
Due to the large structure, it is possible to obtain an effect of significantly reducing noise without deteriorating the magnetic characteristics.

[Brief description of drawings]

FIG. 1 is an assembled perspective view of a transformer core according to the present invention.

FIG. 2 is a schematic assembly perspective view of a transformer using the transformer core according to the present invention.

FIG. 3 is an explanatory view showing a comparison of iron loss characteristics of iron cores using 6.5% silicon steel sheets and grain-oriented silicon steel sheets.

FIG. 4 is an explanatory view showing a comparison of exciting capacity characteristics of iron cores using a 6.5% silicon steel sheet and a grain-oriented silicon steel sheet.

FIG. 5 is an explanatory view showing a noise characteristic comparison of iron cores using 6.5% silicon steel sheet and grain-oriented silicon steel sheet.

FIG. 6 is an explanatory diagram showing a conventional inverter power supply transformer.

[Explanation of symbols]

4 is a combination iron core, 5 is a grain-oriented silicon steel plate, 6 is a low magnetostrictive material (6.5% silicon steel plate), 7 is a leg part, and 8 is a yoke part.

Claims (1)

[Claims] 1. An iron core formed by laminating grain-oriented silicon steel sheets is arranged at a central portion in the stacking direction, and iron cores made by laminating a material having a magnetostriction lower than that of the grain-oriented silicon steel sheet are arranged on both sides thereof. A transformer laminated iron core, characterized in that both iron cores are integrally formed, and a cross sectional area ratio of the iron core of the low magnetostrictive material in the leg portion is made larger than a cross sectional area ratio of the iron core of the low magnetostrictive material in the yoke portion.