JP2580367Y2 - Choke coil for noise filter - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a choke coil for a noise filter having both a normal mode choke coil and a common mode choke coil using one magnetic core to suppress electromagnetic noise of an electronic circuit.

[0002]

2. Description of the Related Art Conventionally, when a normal mode choke coil and a common mode choke coil are formed in the same circuit, as shown in FIG. 9, a soft magnetic ferrite core having an air gap formed in a magnetic path or a metal soft magnetic powder is used. Normalized choke coils 24 and 25 in which a powder core is wound, and a common mode choke coil 26 in which two windings are wound in a common mode on a closed magnetic circuit annular core having high relative permeability.
, The mounting space is large, and
Since each coil is individually mounted on a substrate, many components are required to be mounted on the substrate, and there is a problem that the cost is high.

[0003]

[Problems to be Solved by the Invention] In order to eliminate these problems, the present invention is to form a normal mode choke coil and a common mode choke coil integrally with one magnetic core. It is an object of the present invention to provide a noise filter choke coil in which an inexpensive normal mode choke coil and a common mode choke coil are integrated.

[0004]

SUMMARY OF THE INVENTION According to the present invention, there is provided a magnetic core having four magnetic legs having a high relative magnetic permeability characteristic and having a gap in a magnetic path of two magnetic legs on both sides. In the direction in which the magnetic fluxes generated by the currents flowing through the windings on the magnetic leg provided with the magnetic field and the central closed magnetic path magnetic leg urge each other.
The magnetic flux of the central magnetic leg created by the winding wound on one magnetic leg is configured to be wound in the direction to cancel each other. One set of magnetic cores acts on two modes of electromagnetic noise, normal mode and common mode. And an effective choke coil.

That is, the present invention provides: Two input windings are applied from the input side to the outer legs of a four-leg magnetic core having high relative permeability characteristics and having air gaps on both outer sides and two magnetic legs forming a closed magnetic path in the center. A normal mode winding in which windings are applied in opposite directions to each other, and two normal mode windings are connected in series with the normal mode winding.
Each of the two central closed magnetic path magnetic legs is wound so that the magnetic field directions generated by currents flowing in opposite directions to the adjacent normal mode windings of the two windings generate magnetic flux in the same direction in the closed magnetic path magnetic legs. A choke coil for a noise filter characterized by forming a common mode winding. 2. 2. The choke coil for a noise filter according to claim 1, wherein an air gap is provided in two magnetic legs of the four leg magnetic cores forming the choke coil, and the other two magnetic legs are formed of a four leg magnetic core comprising a closed magnetic path magnetic core. This is a characteristic choke coil for a noise filter. 3. In the choke coil for a noise filter according to claim 1, a cross-sectional area of a magnetic leg forming a normal mode choke coil, a cross-sectional area of a magnetic leg forming a common mode choke coil, and a gap length are formed in any shapes. A noise filter choke coil comprising a four-leg magnetic core.

[0006]

FIG. 1 shows an embodiment of a choke coil for a noise filter according to the present invention. In FIG. 1, a magnetic core having four magnetic legs is provided with a gap 6 and a gap 7 on both outer magnetic legs. The two magnetic legs are provided with an outer air gap 6 on a four-leg core formed in a closed magnetic path having no air gap in the magnetic path, and a line leading to an input in which two currents flow in opposite directions from the input side. A winding wound around the magnetic leg provided with the gap 7 in the opposite direction as viewed from the input side, and a winding exit from each of the outer magnetic legs is connected to the winding wound around the central magnetic leg. It is assumed that the magnetic flux 4 and the magnetic flux 5 generated in the central magnetic leg generated by the current in the opposite direction and the magnetic flux generated by the outer magnetic legs are wound in the same direction in the central magnetic leg. Therefore, the direction of the magnetic flux 9 of the outer magnetic leg and the direction of the magnetic flux 5 of the central magnetic leg are in the same direction, and the magnetic flux 8 of the outer magnetic leg with air gap, the magnetic flux 4 and the magnetic flux 9 of the central closed magnetic path magnetic flux 9 and the magnetic flux 5 cancel each other out. As a result, two normal mode choke coils are formed by a magnetic leg having an outer gap and adjacent magnetic legs on both sides of a central closed magnetic path magnetic leg. The two center magnetic legs form a choke coil for a noise filter which becomes a common mode choke coil.

[0007]

FIG. 1 shows a noise filter circuit and a choke coil for a noise filter according to the present invention. The magnetic legs have air gaps 6 and 7 on both outer sides of a magnetic core, and the four magnetic legs form two closed magnetic paths in the center. A four-leg magnetic core 1 is formed by winding a conducting wire through which a line current flows into opposite outer magnetic legs in the same direction so that the directions in which line currents flowing in opposite directions flow in the same direction. Each of the conductors wound around the outer magnetic leg is wound around the adjacent magnetic leg so that the windings wound around the two magnetic legs have the same polarity. With such a winding, a normal mode choke coil inserted in series on the input side by the outer magnetic poles provided with the air gaps 6 and the air gap 7 and the central closed magnetic path magnetic leg is formed. A common mode choke coil is formed by the magnetic legs of the two closed magnetic paths. At this time, the magnetic flux 8 passing through the air gap 6 on both sides and the magnetic flux 9 passing through the air gap 7 are in the same direction in the magnetic flux 4 and the magnetic flux 5 passing through the central closed magnetic path magnetic leg and the magnetic flux formed by the normal mode choke coil. The magnetic flux leaking into the closed magnetic circuit is canceled out by the magnetic flux generated by the two magnetic legs forming a pair. A space 6, usually provided on both outer sides,
The gap length of the gap 7 is the same gap length, the number of windings is the same, and the windings wound on the magnetic legs of both central closed magnetic paths are the same number of windings on both magnetic legs. It is wound. FIG. 2 shows an example of a magnetic core used in a choke coil for a noise filter according to the present invention.
A split core consisting of a leg core and an I-shaped core, and a gap 6 and a gap 7 are provided on both outer sides. FIG. 4 shows the magnetic core shape when it is necessary to increase the cross-sectional area of the closed magnetic path magnetic legs on both sides of the center and to increase the inductance value of the common mode choke coil. FIGS. 5 and 6 show windings on the central magnetic legs. FIG. 7 shows an example of a magnetic core in which the winding does not exceed the height of the core when applied, FIG. 7 shows an example of a magnetic core in which the two-part magnetic core of FIG. 5 is integrally formed in a closed magnetic circuit, and FIG. 2 is an example of a magnetic core formed in a closed magnetic circuit in which the two-divided magnetic core is integrally formed. In the embodiment of the present invention, the length and the size of the magnetic legs of the magnetic legs provided with the air gaps on both sides are the same, and the description has been made with the four-leg magnetic core. Naturally, the choke coil for the noise filter of the present invention can be formed even if the magnetic legs are asymmetric.

[0008]

[Effects of the Invention] A magnetic core composed of four magnetic legs with air gaps provided on both outer sides and a central magnetic leg formed in a closed magnetic path, windings of the same polarity with the same number of turns on both outer sides, and a closed magnetic path of two central magnetic legs. By forming an inductor in which windings in which magnetic fluxes of the same direction are generated by magnetic fluxes of the same polarity on both outer sides and currents flowing in the respective windings in opposite directions to the respective windings are formed, two series connected to two input lines are formed. It is possible to form a noise filter choke coil including one normal mode choke coil and one common mode choke coil. In addition, the choke coil for the noise filter of the present invention has a small mounting shape, and the split type magnetic core and the inductance values required by the normal mode choke coil and the common mode choke coil,
An optimum noise filter choke coil can be formed by changing the shape of the magnetic core.

[Brief description of the drawings]

FIG. 1 is a diagram showing an integral magnetic core shape and a winding structure forming a choke coil for a noise filter according to the present invention.

FIG. 2 is an external perspective view showing the shape of a split magnetic core forming a choke coil for a noise filter according to the present invention.

FIG. 3 is an external perspective view showing a four-leg core and an I-shaped core forming a choke coil for a noise filter according to the present invention.

FIG. 4 is an external perspective view of a magnetic core forming a noise filter according to the present invention.

FIG. 5 is an external perspective view of a magnetic core forming a noise filter according to the present invention.

FIG. 6 is an external perspective view of a magnetic core forming a noise filter according to the present invention.

FIG. 7 is an external perspective view of a magnetic core forming a noise filter according to the present invention.

FIG. 8 is an external perspective view of a magnetic core forming a noise filter according to the present invention.

FIG. 9 is a diagram showing a normal mode choke coil and a common mode choke coil forming a conventional noise filter.

[Explanation of symbols]

1,10,11,12,16,17,20,224
Leg core 2 Common mode winding 3 Normal mode winding 4, 5, 8, 9 Magnetic flux 6, 7 Air gap 12 I-shaped core 24, 25 Normal mode choke coil 26 Common mode choke coil

Claims (3)

(57) [Scope of request for utility model registration] 1. Two input windings are provided on both outer magnetic legs of a four-leg magnetic core having a high relative permeability characteristic and having air gaps on both outer sides and two magnetic legs forming a closed magnetic path in the center. A normal mode winding in which the wires are wound in opposite directions when viewed from the input side, and two central closed magnetic path magnetic legs in series with the normal mode winding, the normal mode winding being adjacent to the two windings. A choke coil for a noise filter, wherein a common mode winding is formed such that a magnetic field generated by currents flowing in opposite directions in the winding generates a magnetic flux in the same direction on a closed magnetic path magnetic leg. 2. The choke coil for a noise filter according to claim 1, wherein an air gap is provided in two magnetic legs of the four leg magnetic cores forming the choke coil, and the other two magnetic legs are formed of a closed magnetic circuit core. A choke coil for a noise filter, comprising a magnetic core. 3. The choke coil for a noise filter according to claim 1, wherein a cross-sectional area of a magnetic leg forming a normal mode choke coil, a cross-sectional area of a magnetic leg forming a common mode choke coil, and a gap length are arbitrary. 4 formed in the shape of
A choke coil for a noise filter, comprising a leg core.