JPS59189609A - Magnetic core - Google Patents

Abstract

PURPOSE:To obtain a magnetic core out of which the flux scarecely leaks and which has a high permeability in a low magnetic field by coupling a high permeability core and a compressed powder core. CONSTITUTION:A magnetic core is composed by coupling a magnetic core made of high permeability magnetic material and a compressed powder core. An amorphous core has excellent frequency characteristics of the permeability and low iron loss so that it has an advantage to be used as a high permeability core. When the permeability of the amorphous material exceeds 1,000, a feature of the core which has L-shape characteristics can be utilized which is effective for reducing the size of the core. When Co base amorphous material which has small magnetostriction is used, it is especially advantageous because that material is durable against the stress and impact during manufacture of the core. This core has L-shape characteristics when it is used as a smoothening choke coil of a switching source and the flux scarecely leaks out of the core so that it is especially useful for a specified application.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic core that is a composite of a magnetic core made of a magnetic material with high magnetic permeability and a powder magnetic core. , silicon steel core, permalloy.

A powder magnetic core made of iron or other materials was used.

When a silicon steel magnetic core is used for a choke, a relatively large current flows through the coil wound around the magnetic core, so it is necessary to provide a gap to prevent magnetic saturation of the core material. For this reason, there is magnetic flux leakage due to the leakage, which can easily become a source of noise, which can cause problems when incorporated into electronic equipment.

On the other hand, powder magnetic cores have no gaps and are difficult to magnetically saturate, so they are advantageous because they do not have the problem of magnetic flux leakage.

However, in a choke using a powder magnetic core, the magnetic permeability of the core material is nearly constant from a low magnetic field to a magnetic field where the magnetic core is saturated, and the change in inductance is small even when the current flowing through the coil becomes small. For this reason, when a powder magnetic core is used as a smoothing choke in a switching power supply, the output voltage fluctuates when the load current is small, which poses a problem. To solve this problem, a circuit was created to suppress fluctuations in the output voltage. Therefore, the cost increases due to an increase in the number of parts. Problems such as the increase in the number of parts and the increase in the size of the power supply occur.
When the current flowing through the coil is small, the inductance is large, and the current that saturates the magnetic core from a certain current. A choke using a core with a single-character characteristic in which the change in magnetic permeability is small until it is saturated is required. In order to solve this problem, a magnetic core for a choke has been proposed in which a magnetic material with high magnetic permeability is disposed near the gill lubricant of the core. However, in this method, since there is a gap in the magnetic core, there is a leakage of magnetic flux at the gap portion, which may cause problems such as noise when used in electronic equipment, etc., and is not very preferable.

An object of the present invention is to improve the drawbacks of the above-mentioned prior art and to provide a magnetic core that has almost no magnetic flux to the outside of the magnetic core and has high magnetic permeability in a low magnetic field.

The main point of the present invention is that instead of the conventional magnetic core with a single-shaped core with high magnetic permeability in a low magnetic field, a core made of steel or permalloy having constant magnetic permeability is used. The object of the present invention is to provide a magnetic core having a single-character characteristic in which leakage of magnetic flux to the outside of the magnetic core is small, by combining a magnetic core with high magnetic permeability.

In particular, as a high permeability magnetic core, it is advantageous to use an amorphous magnetic core because it has good frequency characteristics of 'fi magnetic permeability and low iron loss.

In addition, when the magnetic permeability of the amorphous 'vJ diagonal is 1000 or more, the characteristics of the magnetic core exhibiting single-character characteristics can be particularly utilized, contributing to miniaturization of the magnetic core.

Further, it is particularly advantageous to use an amorphous magnetic core having a small CO-based magnetostriction because it is strong against stress and impact during core manufacturing.

In addition, this magnetic core is particularly excellent when used in a smoothing choke of a switching power supply because it exhibits cross-curved characteristics and there is no leakage of magnetic flux to the outside of the magnetic core.

The present invention will be explained below according to examples.

Embodiment 1 FIG. 1 is a diagram showing a part of an embodiment of the magnetic core of the present invention. As shown in the figure, the magnetic core is composed of a powder magnetic core and a magnetic core using a high magnetic permeability magnetic material, and since there is no -V top, the leakage magnetic flux is There are two examples in the figure that are more right-handed than the magnetic core (see Figure 2), but it is clear that structures that can obtain similar effects are included in the scope of the present invention.Example 2 Figure 2 shows the magnetic core of the present invention. It is a diagram showing an example of DC superposition characteristics.For comparison, the DC superposition characteristics of MO Permallo 1 igus 1~core are also shown.

As is clear from the figure, the permeability in the low magnetic field is increasing,
It can be seen that it is particularly excellent as a magnetic core for smoothing blocks in switching power supplies.

In addition, it was confirmed that the magnetic core using amorphous CaL3 has a high magnetic permeability, especially in a low magnetic field.

The present invention has a small effect in that it is possible to prevent output voltage fluctuations of conventional switching power supplies at low currents, and also to reduce problems such as noise caused by leakage magnetic flux.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing an example of the structure of the magnetic core according to the present invention, and Fig. 2 is a diagram showing an example of the DC superimposition characteristics of the magnetic core according to the present invention in comparison with that of a MO permaloid core. . Procedural amendment written August 18, 1980, Special Y ) 2-chome 1-2 name (5
08) Hitachi Metals Co., Ltd. Telephone: Tokyo 03-284-4642 "Detailed Description of the Invention" column of Akirall1l@. Contents of the Amendment As shown in the attached sheet, the description in the "Detailed Description of the Invention" column in Contents of the Amendment 1 is corrected as follows. (1) Insert the following sentence after "So," in the second line of page 3 of the specification. "It was not desirable. Therefore, for this purpose." (2) In line 13 of the same page of the same book, "in some cases" is corrected to "etc." (3) Delete "Squid J" from "Dai Riki" at the end of the same page in the same book. (4) Change "Amorphous magnetic core is" to "Amorphous magnetic core" on page 4, line 10 of the same book. (5) In line 11 of the same page of the same book, ``When used'' is corrected to ``If used.'' (6) In line 15 of the same page of the same book, "Excellent." is corrected to "Useful. J." -

Claims (1)

[Claims] 1. A magnetic core characterized by a composite of a magnetic core made of a magnetic material with high permeability and a powder magnetic core. 2. The magnetic core according to claim 1, wherein an amorphous material is used as the magnetic material having high magnetic permeability. 3. As a magnetic material with high magnetic permeability, the initial magnetic permeability is 100.
The magnetic core according to claim 2, characterized in that 0 or more amorphous materials are used. 4. The magnetic core according to claim 3, characterized in that a CO-based amorphous material is used as the magnetic material having high magnetic permeability. 5. The magnetic core according to claims 1 and 2, which is used as a smoothing choke for a switching power supply.