JPH0399410A - Wound core - Google Patents

Abstract

PURPOSE:To obtain a wound core having high interlayer insulating resistance and an excellent amorphous magnetic thin band by a method wherein a cobalt amorphous magnetic thin band, having the uniform value of magnetic strain, and an insulating film are lap-wound. CONSTITUTION:A cobalt amorphous magnetic thin band having the magnetic strain of 1X10<-6> or less such as METGLAS 2705M manufactured by Allied Signal Corporation, for example, is used as a tape-like amorphous magnetic thin band 1. An insulating film 2, having the tape width same as or wider than the plate width of the above-mentioned thin band 1 is lap-wound in sandwitch form through the intermediary of a guide roller 3, and a wound core 4 is formed. A polyester film is used as the above-mentioned insulating film 3. Besides, as no annealing is conducted on the lap-wound core 4, the insulating film 3 having no heat-resisting property can be used.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a wound core made of an amorphous magnetic ribbon used in induction equipment such as transformers and reactors operated at high frequencies.

(Prior art) In recent years, amorphous magnetic ribbons with excellent magnetic properties have been used as iron core materials for induction equipment such as transformers, replacing conventional silicon steel sheets, permalloy, ferrite, etc. It is being considered.

In particular, for induction equipment that operates at high frequencies, the characteristics of amorphous magnetic ribbons include the fact that tape-shaped ribbons can be easily produced, and high-frequency iron loss is reduced due to high specific resistance. applications are increasing.

However, since amorphous magnetic ribbons are generally not coated with an insulating coating, the insulation resistance between the core layers affects transformer cores used at frequencies of several tens of kHz or higher, resulting in an increase in eddy current loss at high frequencies. This can sometimes be a problem, especially in high-voltage devices such as power transformers, where the voltage per turn of the winding is high, so if the insulation resistance between the core layers is high, local heating may occur in the core.

As shown in JP-A-63-6822, a method for preventing the increase in eddy current loss in the iron core used in high-frequency transformers is to use an amorphous magnetic thin strip and a tape width equal to or greater than this plate width. There is a method in which a heat-resistant film having a heat-resistant film is layered and wound to form an iron core, and then annealed, or a method in which a heat-resistant insulating film MgO
Methods such as coating and winding are being considered.

(Problem to be solved by the invention) However, when an amorphous magnetic ribbon and a heat-resistant film are layered and wound,
In the method of subsequently annealing this iron core, an increase in wax current loss can be prevented by interlayer insulation, but during annealing, stress is applied to the amorphous magnetic ribbon due to heat shrinkage of the heat-resistant film. The inherent low loss and high square hysteresis characteristics of the magnetic ribbon may be impaired.

On the other hand, in the method of coating the surface of an amorphous magnetic ribbon with a heat-resistant inorganic insulating film and winding it to form a wound core, the surface of the amorphous magnetic ribbon can be coated uniformly, but the edges of the ribbon Since the parts cannot be completely coated, there are problems such as increased melt current loss due to edge contact.

In particular, in iron cores for high-voltage power transformers, if the edges come into contact, there are problems such as insulation short-circuiting and local heating.

The present invention has been made to solve the above-mentioned problems, and it is possible to prevent an increase in interlayer eddy current loss due to high frequencies in a wound core formed by winding an amorphous magnetic thin ribbon, and to The purpose is to fully utilize the excellent low loss and high square hysteresis characteristics inherent in the band to obtain a high quality wound core.

[Structure of the Invention] (Means for Solving the Problems) The wound core of the present invention is made of a cobalt-based amorphous magnetic thin strip having a magnetostriction of 1×10 −6 or less, such as METGLAS2705M manufactured by Allied Signal Co., Ltd. It is characterized by being constructed without annealing by overlapping and winding insulating films having a tape width equal to or greater than the width of the strip.

(Function) According to the present invention, a cobalt-based amorphous magnetic ribbon having a magnetostriction of 1×10 −6 or less and an insulating film are wound in an overlapping manner. Therefore, the insulation resistance between the ribbon layers is high,
Increase in melt current loss due to high frequency can be prevented.

Furthermore, since the insulating film used has a film width equal to or greater than that of the amorphous magnetic ribbon, there is no reduction in insulation resistance due to contact with the end faces of the amorphous magnetic ribbon. Furthermore, since the wound core is wound with a cobalt-based amorphous magnetic ribbon having a magnetostriction of 1.times.10@-6 or less, there is no deterioration in magnetic properties due to bending stress generated during winding. Therefore, there is no deterioration of magnetic properties due to bending stress in high magnetostrictive materials such as iron-based amorphous magnetic ribbons, and if a cobalt-based amorphous magnetic material is used, strain relief annealing after winding is unnecessary. There is no need to use a heat-resistant film that can withstand annealing for the insulating film.

(Example) An example of the present invention is shown in FIGS. 1 and 2. In FIG. 1, a tape-shaped amorphous magnetic ribbon 1 includes a cobalt-based amorphous magnetic ribbon with a magnetostriction of 1×10 −6 or less;
For example, Allied Signal's METGLA32705M
An insulating film 2 having a tape width equal to or greater than the plate width of the ribbon 1 is simultaneously stacked in a sandwich manner via a guide roller 3 to form a wound core 4. As this insulating film 3, a 6 μm polyester film was used.

Note that since the wound core 4 that has been wound overlappingly is not annealed, the insulating film 3 used therein does not need to be a heat-resistant film.

Figure 2(a) shows a wound core 4 wound in the manner shown in Figure 1.
FIG. 2(b) shows a cross-sectional view taken along the line X--X.

It is known that the relationship between the interlayer resistance of the iron core and the increase in iron loss due to eddy current loss is given by the following equation (1).

ρ Here, Wo: increase in eddy current loss, f: frequency.

Bm: magnetic flux density, a: core width, t: plate thickness, ρ: interlayer resistance, ni: proportionality constant.

That is, according to equation (1), the increase in eddy current loss is proportional to the square of the frequency and inversely proportional to the interlayer resistance, so it is necessary to increase the interlayer resistance for iron cores used at high frequencies.

In the embodiment of the present invention, the amorphous magnetic band 1 constituting the wound core 4 is
Since the layers are insulated by the insulating film 2 having a high insulation resistance, the wound core 4 can prevent an increase in wax current loss due to interlayer short circuit.

Furthermore, since the tape width of the insulating film 2 is equal to or greater than the plate width of the amorphous magnetic ribbon 1,
There is no reduction in insulation resistance due to contact with the end surfaces of the amorphous magnetic ribbon 1, and even in equipment where high voltage is applied at high frequency, insulation breakdown does not occur and local heating does not occur.

In particular, saturable reactor cores used at high frequencies and high voltages require excellent square hysteresis characteristics because of the need to obtain a large amount of change in magnetic flux with a small magnetizing force.

In this example, since a cobalt-based amorphous magnetic ribbon with almost zero magnetostriction is used as the amorphous magnetic ribbon 1, the deterioration of characteristics due to bending stress generated when winding the wound core 4 is avoided. It showed high square hysteresis characteristics.

FIG. 3 shows a DC hysteresis curve measured to investigate the influence of hysteresis on the squareness ratio due to the annealing of the wound core 4 around which the cobalt-based amorphous magnetic ribbon 1 was wound.

In the figure, the hysteresis curve A is 30°C at a temperature of 320°C.
The hysteresis curve B is the one without annealing.

It can be seen that there is almost no difference in the squareness ratio and saturation magnetization between the former and the latter. That is, cobalt-based amorphous magnetic ribbon 1
It was discovered that the wound core 4 using the above-mentioned steel exhibits excellent square hysteresis characteristics even without strain relief annealing.

Further, in order to reduce the size of the wound core 4, it is desirable that the insulating film 2 to be overlapped is as thin as possible. In this example, a tape with a thickness of 6 μm was used as the insulating film 2, and a tape with a thickness of 25 μm was used as the cobalt-based amorphous magnetic ribbon 1. In this case, the space factor of the wound core 4 was approximately 7096,
A wound core 4 with a high space factor was obtained as an insulated core.

[Effects of the Invention] As explained above, according to the wound core according to the present invention, a wound core made of an amorphous magnetic ribbon having high interlayer insulation resistance and excellent square hysteresis characteristics can be obtained.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing the state of the wound core according to the present invention during manufacture, FIG. 2(a) is a perspective view of the wound core, and FIG. 2(b) is the line X-X-X in FIG. The line cross-sectional view and FIG. 3 are explanatory diagrams showing a comparison of hysteresis characteristics depending on whether a wound core made of a cobalt-based amorphous magnetic ribbon is annealed or not. 1... Cobalt-based amorphous magnetic ribbon. 2...Insulating film, 4...Wound iron core.

Claims (1)

[Claims] A wound iron core constructed by overlapping and winding an amorphous magnetic ribbon with a magnetostriction of 1×10^-^6 or less and an insulating film with a tape width equal to or greater than the plate width of the ribbon without annealing.