JPH10208947A - Core with gap for reactor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a core with a gap for a reactor wherein the increase of the magnetic strain generated by the force for clamping axially the core is suppressed and noises are reduced thereby. SOLUTION: This core with a gap comprises a laminate of grain oriented silicon steel plates to form block cores 2 and yoke cores 4, 5 with non-magnetic insulators 3 for a gap interposed between the block cores 2 to form a leg core. In this case, using as the grain oriented silicon steel plate the one having an inner tension not smaller than the tension equal to 15kg/cm<2> plus a magnetic attraction force generated by the gap, the action of a compression force applied to the grain oriented silicon steel plate in its axial direction when clamping the core is reduced to eliminate the rapid increase of a magnetic strain.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a core with a gap for a reactor.

[0002]

2. Description of the Related Art FIG. 1 is a schematic front view of an example of a core structure of a core type reactor with a gap, represented by a shunt reactor, wherein 1 is a leg core, 4 is an upper yoke core, 5 is a lower yoke core, Reference numerals 6 and 7 denote fastening fittings, and reference numeral 8 denotes a fastening stud. The leg iron core 1 is formed in a columnar shape by alternately stacking a block iron core 2 formed by laminating directional silicon steel plates and a non-magnetic insulator 3 for a gap inserted between the block iron cores 2. .

[0003] In the iron core structure, fastening irons 6 and 7 are applied to the leg iron core 1 on the upper surface of the upper yoke iron core 4 and the lower surface of the lower yoke iron core 5. Insert the tightening stud 8 through the nut and insert the nut 9
, A tightening force is generated between the upper and lower fasteners 6 and 7 and transmitted to the leg core 1 via the upper and lower yoke cores 4 and 5.

[0004] In the iron core structure thus configured, since there is a gap 3, F = Bm ² × 1 between the block iron cores 2.
Assuming that the magnetic attraction force F of 0 ⁻⁴ / 2 × μ ₀ × 9.8 (Kg / cm ² ), for example, the magnetic flux density Bm is 1.5 T (tesla), 1.5 ² × 10 ⁻⁴ / 2 × 4π. × 10 ⁻⁷ × 9.8
= 9.1 (Kg / cm ² ). For this reason, the leg core 1 is tightened by the upper and lower yoke cores 4 and 5 with a force that is greater than this force and is called a so-called axial core tightening force so that the leg core 1 is not loosened by the magnetic attraction force.

That is, since the core has its axial direction set in the roll direction (rolling direction) of the directional silicon steel sheet having low magnetic resistance from the flow of magnetic flux, the axial core clamping force is determined by the roll direction of the silicon steel sheet. Will be applied as a compression force.

[0006]

The iron core reactor with a gap has a problem that the noise is relatively large, and it is desired to reduce the noise. One of the causes of the noise is a magnetostriction phenomenon of a silicon steel sheet.
Magnetostriction is a phenomenon in which a silicon steel sheet expands and contracts when a magnetic flux flows through the silicon steel sheet. The relationship between this magnetostriction and the force applied to the directional silicon steel sheet is as shown in FIG. The magnetostriction is small when tension is applied, and the change in magnetostriction is small with an increase in tension.
When the pressure is 5 kg / cm ² or less, the magnetostriction increases, and the direction of the force applied to the grain-oriented silicon steel sheet changes. For this reason, it is considered that one of the factors that the reactor noise is large is that the magnetostriction is increased due to the axial core tightening force.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides a reactor core with a gap, which suppresses an increase in magnetostriction caused by an axial core clamping force, thereby reducing noise. With the goal.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a reactor with a gap having a gap in a magnetic path, in which a directional silicon steel sheet is laminated and a magnetic attractive force generated by the gap as the directional silicon steel sheet. 15kg
This is achieved by using a directional silicon steel sheet having an internal tension equal to or higher than the tension obtained by adding / cm ² .

According to a feature of the present invention, a directional silicon steel sheet formed by giving an internal tension equal to or greater than a tension obtained by adding 15 kg / cm ² to a magnetic attraction force generated when assembled in an iron core structure is used. Therefore, even if it is tightened so that it is not loosened by the magnetic attraction force, the grain-oriented silicon steel sheet is almost 15 kg / c.
The tension of m ² is maintained and the magnetostriction is small, and the noise generated by this magnetostriction is reduced.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a reactor core with a gap according to the present invention will be described. The core structure of the reactor core with a gap is configured in the same manner as the core structure shown and described in FIG. The iron core according to the present embodiment has a surface of a grain-oriented silicon steel sheet having a thickness of 0.23 mm coated with a ceramic coating, and 15 Kg / cm ² is applied to a magnetic attraction force generated when the core is assembled by the ceramic coating. It is configured by laminating directional silicon steel sheets formed with an internal tension equal to or higher than the added tension.

[0011] With the iron core thus configured, the iron core weight 4
A model reactor of 5 kg was tightened with the same axial tightening force of the iron core as before, and a noise test was performed at 50 Hz and 1.9 T (tesla). The noise measurement result at that time was 4
4.1 db. Similarly, a noise test was performed on a conventional reactor having a core weight of 45 kg at 50 Hz and 1.9 T (tesla). The noise measurement result at that time was 50.0 db.

As is clear from the noise measurement results of both reactors, the reactor of this embodiment has a noise of 5.9 db lower than that of the conventional reactor. Note that the 5.9 db difference is 0.26 times (10
^-0.59 = 0.26 times), which is a reduction of about one fourth.

[0013]

As described above, according to the present invention, even if the iron core is tightened, there is no sudden increase in magnetostriction, and therefore a low-noise reactor can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic front view of an example of an iron core structure of an iron core reactor with a gap.

FIG. 2 is a characteristic diagram showing a relationship between force and magnetostriction of a grain-oriented silicon steel sheet.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Leg iron core 2 Block iron core 3 Non-magnetic insulator for gap 4 Upper yoke iron core 5 Lower yoke iron core 6, 7 Tightening bracket 8 Tightening stud 9 Nut

Claims (1)

[Claims] A directional silicon steel sheet is laminated, and in a reactor core with a gap having a gap in a magnetic path, a tension equal to or greater than a magnetic attractive force generated by the gap plus 15 kg / cm ² as the directional silicon steel sheet. A gapped iron core for a reactor, characterized by using a grain-oriented silicon steel sheet having an internal tension as described above.