JP2007073903A - Cored coil - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cored coil where inductance changes nonlinearly so as to be large in the case of small current and to be small in the case of large current without performing complicated coil processing of providing a gap in a magnetic path or forming a coil in two magnetic paths of different magnetic resistances. <P>SOLUTION: A toroidal coil 11 is composed of a core 12 and the coil 13 formed by winding a conductor around the core 12. The core 12 is a toroidal core constituted by connecting two annular core members 14 and 15. The respective core members 14 and 15 are formed of magnetic materials of different magnetic resistances. Material which has comparatively high magnetic permeability and which is easily saturated magnetically is used for the core member 14, and material which has low magnetic permeability and which is hardly saturated magnetically is used for the core member 15. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a cored coil, and more particularly to a cored coil suitable as a choke coil used for a switching power supply or the like.

  A switching control type power supply circuit such as a DC-DC converter uses a choke coil for attenuating and smoothing a ripple component included in a rectified direct current. In order to attenuate the ripple component, it is necessary that the inductance is large. However, if a core with high magnetic permeability is used to increase the inductance, magnetic saturation occurs at a large current.Therefore, a gap is provided in a part of the core, or the magnetic powder is subjected to compression treatment and subjected to compression molding. The technique of reducing the magnetic permeability as a core is used.

  On the other hand, on the power circuit side, when trying to supply efficiency efficiently in a wide range from small current (light load) to large current (heavy load), the ripple current becomes larger than the average current at the small current, There was a problem that efficiency became worse. In order to improve the efficiency at a small current, a choke coil having a particularly large inductance at a small current is desired.

In order to construct a power supply that efficiently covers a wide output range from large current to small current while taking into account power conversion efficiency and load fluctuation response characteristics, a coil with a large inductance at small current and a small inductance at large current ( Inductors) are disclosed (for example, see Patent Document 1). As a method for making the inductance have the nonlinear characteristics as described above, in Patent Document 1, it is formed by providing two types of gaps with different intervals, that is, stepped gaps, in the middle legs of the EI type core. A method is described. In addition, as shown in FIG. 6, a gap 53 is provided in the middle foot portion 52 of the EI type core 51, and a part of the same conductive wire is wound around the middle foot portion 52 to form a first coil 54. Is wound around one outer foot portion 55 to form a second coil 56.
JP 2002-57046 A (paragraphs [0003], [0016] to [0021] of the specification, FIGS. 1 and 8)

  However, when there is a gap in the core, there is a problem that noise is generated due to the leakage magnetic flux from the gap, or that the proximity effect occurs due to the leakage magnetic flux interlinking with the windings, resulting in an increase in copper loss. In addition, there is a problem that it takes time to process the stepped gap. In the configuration in which a part of the same conducting wire is wound around the middle foot portion 52 to form the first coil 54 and a part is wound around one outer foot portion 55 to form the second coil 56, the winding step There is a problem that becomes complicated.

  The present invention has been made in view of the above problems, and its purpose is to perform complicated winding processing such as providing a gap in a magnetic path or forming a winding in two magnetic paths having different magnetic resistances. Therefore, an object of the present invention is to provide a cored coil that can change nonlinearly so that the inductance is large when the current is small and small when the current is large.

  In order to achieve the above object, according to the first aspect of the present invention, a plurality of core members formed of magnetic materials having different magnetic permeability are joined, and a plurality of annular magnetic paths having no gap and different magnetic resistances are formed. A core provided; and a winding wound around the core in common with the plurality of magnetic paths. The shape of the core is not limited to the toroidal shape (donut shape), and there are an EE type in which two E-shaped cores are combined, an EI type in which an E-shaped core and an I-shaped core are combined, and the like.

  In this invention, the core is formed by joining a plurality of core members formed of magnetic materials having different magnetic permeability, and having a plurality of annular magnetic paths with different magnetic resistances, so that the current flowing through the coil is small. In this case, a relatively high inductance value appears at both ends of the coil due to a magnetic path having a high magnetic permeability and a small magnetic resistance formed of a magnetic material that is easily magnetically saturated. In addition, when the current flowing through the coil (winding) is large, a relatively low inductance value appears at both ends of the coil due to a magnetic path formed of a magnetic material having a low magnetic permeability and hardly magnetically saturated. Therefore, the inductance is large when the current is small and small when the current is large, without performing a complicated winding process such as providing a gap in the magnetic path or forming the winding in two magnetic paths having different magnetic resistances. Can change nonlinearly. As a result, it can be used as a choke coil having a high inductance value at a small current (light load). In addition, since there is no gap in each magnetic path, there is no occurrence of noise due to leakage magnetic flux or an increase in copper loss due to the proximity effect.

  The invention according to claim 2 is the invention according to claim 1, wherein the core is configured by combining two core members having the same ring shape in cross section perpendicular to the axial direction, and the core member is It is arranged in parallel with the ring shape. Here, the “annular shape” includes not only an annular shape but also a rectangular or polygonal shape. In the present invention, since the ring shape is the same, assembly and winding are facilitated.

  The invention according to claim 3 is the invention according to claim 2, wherein the core is a toroidal core. In the present invention, the length of the magnetic path is shortened and the resistance of the magnetic path is reduced as compared with the case where the core has a square shape, and the magnetic flux easily flows because there is no corner.

  According to the present invention, the inductance is large when the current is small, without providing a gap in the magnetic path or performing complicated winding processing such as forming the winding in two magnetic paths having different magnetic resistances. Sometimes it can change non-linearly to be smaller.

(First embodiment)
Hereinafter, a first embodiment in which the present invention is embodied in a toroidal coil will be described with reference to FIGS. FIG. 1 is a schematic perspective view of a toroidal coil, and FIGS. 2A and 2B are schematic views for explaining the operation. In FIGS. 2A and 2B, the winding is not shown.

As shown in FIG. 1, the toroidal coil 11 includes a core 12 and a winding 13 formed by winding a conductive wire around the core 12.
The core 12 is a toroidal core formed by joining two (plural) annular core members 14 and 15. Both core members 14 and 15 are formed to have the same inner diameter and outer diameter. That is, the core 12 is configured by combining two ring-shaped core members 14 and 15 having the same cross-sectional shape orthogonal to the axial direction, and the core members 14 and 15 are arranged in parallel with the ring shape. . The ratio of the axial lengths of both core members 14 and 15 is changed according to the target DC superposition characteristics. When the axial lengths of both core members 14 and 15 are the same, the core member 14 is long. The core member 14 may be short. Each of the core members 14 and 15 is made of a magnetic material having different magnetic permeability. That is, the core 12 is provided with a plurality of annular magnetic paths having different magnetic resistances and no gaps.

  One core member 14 is made of a material having a relatively high magnetic permeability and easily magnetically saturated, for example, a ferrite or iron-based amorphous foil strip (hereinafter simply referred to as an amorphous foil strip). Ferrite and amorphous foil strips are used without a low permeability treatment such as heat treatment. The other core member 15 is made of a material having a low magnetic permeability and hardly magnetically saturated, for example, a dust magnetic material such as sendust or amorphous dust.

  The winding 13 is formed by winding a copper wire having an insulating film as a conducting wire around the core 12 a required number of times. That is, the toroidal coil 11 includes a winding 13 that is wound around the core 12 in common with a plurality of magnetic paths.

Next, the operation of the toroidal coil 11 configured as described above will be described.
When the core member 14 and the core member 15 are wound alone, they have different direct current superposition characteristics as shown in FIG. Then, by winding the core 12 which is a combination of both, the DC superposition characteristics as shown in FIG. 3B, that is, when the load current is small, the inductance is large and the load current is large. Accordingly, it is possible to obtain a DC superposition characteristic in which the inductance is reduced and the change is nonlinear. Since the inductance value and the change ratio with respect to the load current vary depending on the magnetic permeability and saturation magnetic flux density of the material of the core members 14 and 15, the ratio of the axial length of the core members 14 and 15, and the cross-sectional area, these values are used. The core 12 having the desired direct current superimposition characteristic can be formed by forming the core 12 by adjusting the above.

  When a current flows through the winding 13 of the toroidal coil 11, when the current flowing through the winding 13 is small, a relatively high inductance value is generated by the magnetic path A of the core member 14 as shown in FIG. Appears at both ends of 13. However, when the current flowing through the winding 13 increases, the inductance value decreases due to the magnetic saturation of the magnetic path A and a relatively low inductance value due to the magnetic path B of the core member 15 appears as shown in FIG. It becomes like this. Therefore, when the toroidal coil 11 is used as a choke coil, a high inductance value is obtained at a small current (light load), and a low inductance value is obtained at a large current (heavy load), thereby improving power supply efficiency in a wide range.

This embodiment has the following effects.
(1) The coil includes a core 12 in which a plurality of core members 14 and 15 formed of magnetic materials having different magnetic permeability are joined, and a plurality of annular magnetic paths having different magnetic resistances and no gaps are provided; 12 is provided with a winding 13 wound in common with the plurality of magnetic paths. Therefore, the inductance is large when the current is small and small when the current is large, without providing a gap in the magnetic path or performing complicated winding processing such as forming the winding 13 in two magnetic paths having different magnetic resistances. Can be changed non-linearly. As a result, it can be used as a choke coil having a high inductance value at a small current (light load). In addition, since there is no gap in each of the magnetic paths A and B, there is no occurrence of noise due to leakage magnetic flux or an increase in copper loss due to the proximity effect.

  (2) The core 12 is a toroidal core. Accordingly, the length of the magnetic path is shortened and the resistance of the magnetic path is reduced as compared with the case where the core has a square shape, and the magnetic flux easily flows because there is no corner.

  (3) The core 12 is formed such that the inner diameter and the outer diameter are the same and the lengths in the axial direction are different. Therefore, even if the combination of the magnetic materials constituting the core members 14 and 15 is the same, the core 12 having a desired DC superposition characteristic can be obtained by changing the thickness ratio of the core members 14 and 15. It becomes possible. In addition, when combined with the change of the magnetic material of the core members 14 and 15, the degree of freedom in changing and adjusting the DC superimposition characteristics becomes higher.

(Second Embodiment)
Next, a second embodiment will be described with reference to FIGS. FIG. 4A is a schematic front view of an EE type coil, FIG. 4B is a schematic side view, and FIG. 4C is a schematic front view showing the middle of assembly. However, the winding is not shown in FIG. In this embodiment, the configuration of the core 12 is different from that of the first embodiment. Specifically, the point that the core 12 is not a toroidal core but an EE type core is greatly different. The same parts as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  The EE coil 20 is configured by joining a core member 21 combining a pair of E-shaped core components 21a and a core member 22 combining a pair of E-shaped core components 22a. The E-shaped core parts 21a and 22a are formed in the same shape and the same size. The core member 21 is made of a material having a relatively high magnetic permeability and easily magnetically saturated, such as ferrite or an amorphous foil strip, and the core member 22 is made of a material having a low magnetic permeability and hardly magnetically saturated, such as sendust or amorphous. A dust magnetic material such as dust is used.

  The winding 13 is provided on the middle legs 21b and 22b of the E-shaped core parts 21a and 22a. The winding 13 is not formed by directly winding a copper wire having an insulating film as a conducting wire around the middle legs 21b and 22b, but as shown in FIG. 4C, the copper wire is wound a required number of times. By inserting the middle foot portions 21b and 22b into the rotated bobbin 23, the middle foot portions 21b and 22b are provided. The winding 13 may be configured to be wound directly around the middle legs 21b and 22b without providing the bobbin 23.

  In this embodiment, when a current flows through the winding 13 of the EE coil 20, if the current flowing through the winding 13 is small, a comparison is made by the magnetic path A of the core member 21 as shown in FIG. A high inductance value appears at both ends of the winding 13. However, when the current flowing through the winding 13 increases, the inductance value decreases due to the magnetic saturation of the magnetic path A, and a relatively low inductance value due to the magnetic path B of the core member 22 appears.

Therefore, this embodiment has the following effect in addition to the same effect as the effect (1) of the first embodiment.
(4) The degree of freedom of shape is higher than that of a toroidal core.

(5) The winding work of the winding wire 13 is simplified as compared with the toroidal core.
(6) When the length of the magnetic path is made the same as that of the toroidal core, the area occupied by the outer shape of the core is smaller than that of the toroidal core, and the degree of freedom of the position to be attached to the power supply device is increased.

The embodiment is not limited to the above, and may be configured as follows, for example.
The shape of the annular core member is not limited to an annular shape like a toroidal core, but may be a polygonal ring such as a square ring.

  The arrangement of the two core members 14 and 15 constituting the core 12 is not limited to the arrangement in which the magnetic paths A and B formed in the core members 14 and 15 are formed in parallel over the entire circumference. For example, two annular core members 24 and 25 formed of magnetic materials having different magnetic permeability may be combined adjacently as shown in FIG. The core member 24 is made of a material having a relatively high magnetic permeability and easily magnetically saturated, and the core member 25 is made of a material having a low magnetic permeability and hardly magnetically saturated. In this embodiment, when a current flows through the winding 13, a relatively high inductance value appears at both ends of the winding 13 due to the magnetic path A of the core member 24 when the current flowing through the winding 13 is small. However, when the current flowing through the winding 13 increases, the inductance value decreases due to the magnetic saturation of the magnetic path A, and a relatively low inductance value due to the magnetic path B of the core member 25 appears.

  ○ In the case where two annular core members 24 and 25 formed of magnetic materials having different magnetic permeability are adjacently combined as shown in FIG. 5A, both core members 24 and 25 are magnetized. You may form so that the length of a path | route may differ. For example, if the core member 24 formed of a magnetic material having a high magnetic permeability is formed in a shape that shortens the magnetic path, the inductance value at a small current (light load) can be increased even with the same combination of magnetic materials. .

  ○ In the configuration in which the two annular core members 24 and 25 are arranged so that the holes are adjacent to each other, as shown in FIG. 5B, the core members 24 and 25 are combined with the U-shaped core parts 24a and 25a. It is good also as a structure formed.

  ○ When the core members 21 and 22 each have two annular magnetic paths, like the core 12 in the second embodiment, the core 12 has a combination of E-shaped core parts. The shape is not limited to a combination of E-shaped core parts. For example, an E-type core part and an I-type core part may be combined, as shown in FIG. 5C, or an F-type core part may be combined, as shown in FIG. 5D. Thus, a substantially C-shaped core component and a T-shaped core component may be combined.

  The core 12 may be formed by combining three or more annular core members instead of combining two annular core members. Even in this case, by adjusting the permeability of the two cores, the length of the magnetic path, the diameter in the case of the toroidal core, etc., the DC superposition characteristics are increased when the inductance is small and small when the current is large. It can be changed nonlinearly.

(Circle) the cored coil of embodiment may be applied not only to a choke coil but to a transformer.
The following technical idea (invention) can be understood from the embodiment.
(1) In the invention described in claim 1, the core includes a core member including a core component formed in an E-shaped cross section.

The schematic perspective view of the toroidal coil in 1st Embodiment. (A), (b) is a schematic diagram explaining an effect | action. (A) is a graph which shows the direct current superimposition characteristic of each core member, (b) is a graph which shows the direct current superposition characteristic of a core. The 2nd Embodiment is shown, (a) is a schematic front view of EE type coil, (b) is a schematic side view explaining an effect | action, (c) is a schematic front view which shows the assembly | attachment middle. (A) is a schematic diagram of the coil in another embodiment, (b), (c), (d) is a schematic front view of the core in another embodiment, respectively. The schematic front view of EI type coil of a prior art.

Explanation of symbols

  A, B ... Magnetic path, 12 ... Core, 13 ... Winding, 14, 15, 21, 22, 24, 25 ... Core member.

Claims (3)

  A plurality of core members formed of magnetic materials having different magnetic permeability are joined to each other, a core provided with a plurality of annular magnetic paths having different magnetic resistances, and a gap between the cores. A cored coil having a winding wound in common.   The said core is comprised combining 2 core members of the ring shape with the same cross-sectional shape orthogonal to an axial direction, The said core member is arrange | positioned in parallel with the said ring shape overlapping. Core coil.   The cored coil according to claim 2, wherein the core is a toroidal core.

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