JPS6119111A - Choke coil - Google Patents

Abstract

PURPOSE:To enable to prevent the variation of stability of output voltage even when there is a current variation by a method wherein a toroidal form magnetic material with a gap and a gapless magnetic material are formed in one body, and a high permeability material is inserted in the gap. CONSTITUTION:A magnetic material 3a of toroidal shape has no gap, a magnetic material 3b of the same shape as material 3a has a gap, and a high permeability material 14 is inserted into the gap. The inductance of a choke coil constituted as above and having winding structure becomes the inductance which will be determined by the permeability of the materials 3a, 3b and 14 when the DC superposed current running to the choke coil is smaller than the value at which the material 14 is not magnetically saturated. When said DC superposed current is increased and the material 14 is magnetically saturated, the choke coil has the inductance which is determined by the permeability of the material 3b. Accordingly, the running current is hardly turned to discontinuous one even when the current running to the choke coil is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a choke coil used in a filter circuit of a high-frequency switching regulator.

[Prior art]

Traditionally, choke coils used in switching regulators have a small toroidal core with low leakage flux, a core material with good DC superimposition characteristics (such as molybdenum permalloy), and a winding structure as shown in Figure 1. Was. In FIG. 1, 1 is a core and 2 is a winding.

FIG. 2 shows the DC superimposition characteristics of the choke coil shown in FIG. 1, and the inductance has a constant value up to a certain DC current value.

However, at present, there is an increasing demand for lower prices and smaller sizes for switching regulators, and as a means to meet these demands higher frequency switching regulators are being promoted. When a choke coil with a structure is used, it requires a large space and requires manual labor to wind the coil, which has the problem of not being able to meet the demands for lower cost and smaller size. . Further, when this choke coil is used in a filter circuit of a switching regulator, when the load of the switching regulator fluctuates and the output current decreases, the current flowing through the choke coil becomes discontinuous. As a result, there are problems in that the stability of the output voltage deteriorates and the ripple voltage component of the output voltage increases.

[Summary of the invention]

The present invention has been made in view of these points, and an object of the present invention is to provide a choke coil that is small, inexpensive, and does not deteriorate the stability of the output voltage.

In order to achieve such an object, the present invention forms windings for first and second magnetic materials by connecting printed metal wiring provided on an insulating plate and through holes in an insulating material. It is something.

〔Example〕

The present invention will be explained in detail based on examples. FIG. 3 shows a perspective view of an embodiment of the choke coil according to the present invention,
FIG. 4 shows an exploded perspective view.

In FIG. 3, 11.12 is an insulating plate with metal printed wiring formed on its surface, 15 is an insulating material sandwiched between the insulating plates 11.12, 3a and 3b are magnetic materials embedded in the insulating material 15, and 4a , 4b, 4cm, . . . are metal printed wirings formed on the surface of the insulating plate 11. In Figure 4, 5a, ! 5b, 5c... are metal printed wiring formed on the surface (lower surface in the figure) of the insulating plate 12, 6a,
6b, 6c, ... are metal printed wiring 4a, 4b
, 4c, ... and 5a, '5b, 5c, ...
6a-1, 6b-1, 6cm1. ... are provided on the insulating plate 11 to connect the metal printed wirings 4a, 4b, 4c, ... and the through balls 6a, 6b, 6c, ....
i, 6a-2, 6b-2, 6cm2゜... is through with metal printed wiring 5a, 5b, 5c,... ;h
- The through holes 14 provided in the insulating plate 12 for connecting the wheels 6a, 6b, 6c, . . . are made of a high magnetic permeability material inserted into the gear knob of the magnetic material 3b.

Next, the structure of this choke coil will be explained using FIG. 4. The magnetic materials 3a, 3b and the insulating material 15 are both sandwiched between the insulating plates 11.12, the printed metal wiring 4a is connected to the printed metal wiring 5a via the through hole 6a, and the printed metal wiring 5a is connected to the printed metal wiring 5a via the through hole 6b. Since it is connected to the metal printed wiring 4b, the metal printed wiring 4a,
Through hole 6a, metal printed wiring 5a.

A single winding is formed around the magnetic materials 3a and 3b by the electric line constituted by the through hole 6b and the printed metal wiring 4b. If similar connections are repeated multiple times, multiple windings will be formed. In this way, the necessary inductance can be obtained. In addition, if a circuit (not shown) with printed metal wiring is provided on the insulating plates 11 and 12, and the connection between the choke coil and this circuit is completed in advance using printed metal wiring, connection work will be unnecessary. effective.

Next, the DC superimposition characteristics will be explained using FIGS. 4 and 5. As shown in FIG. 4, the magnetic material 3a has no gap, and the magnetic material 3b has a high magnetic permeability material 14 inserted into the gap. The inductance of the choke coil configured in this manner and having the above-described winding structure is such that, first, when the DC superimposed current flowing through the choke coil is less than the DC superimposed current value at which the high magnetic permeability material 14 is not magnetically saturated, the magnetic material 3a
, the inductance is determined by the magnetic permeability of the magnetic material 3b and the high magnetic permeability material 14, and its value is a value Ha corresponding to the DC superimposed current 0 to Ia shown in FIG. The DC superimposed current flowing through the choke coil increases, and the high magnetic permeability material 1
4 becomes magnetically saturated, the inductance of the choke coil becomes an inductance determined by the magnetic permeability of the magnetic material 3a and the magnetic material 3b, and its value becomes a value Hb corresponding to the DC superimposed currents Ia to Ib in FIG. Next, the DC superimposed current flowing through the choke coil increases, and the magnetic material 3al
When i<magnetic saturation, the inductance of the choke coil becomes an inductance determined by the magnetic permeability of the magnetic material 3b, and its value becomes a value Hc corresponding to the DC superimposed current Ib=Ic in FIG. 5. In this way, the inductance of the choke coil increases dramatically as the DC superimposed current decreases.

〔Effect of the invention〕

As described above, the present invention includes an insulating plate on which a part of the winding and a circuit are formed as printed metal wiring, an insulating material sandwiched between the insulating plates and having a through hole, and a gap embedded in the insulating material. The first magnetic material with a gap and the second magnetic material without a gap are integrated into a structure, which facilitates connection work.

Since winding work and the like are eliminated and the mounting method is planar, it has the effect of realizing lower cost and smaller size when used in a switching regulator. In addition, the inductance of the choke coil is made to increase dramatically as the DC superimposed current decreases, so when the present invention is applied to a filter circuit of a switching regulator, the load of the switching regulator fluctuates and the output current decreases, resulting in a choke coil. Even if the current flowing through the coil decreases, the current flowing through the choke coil is less likely to become discontinuous, so the stability of the output voltage does not deteriorate and the ripple component of the output voltage is less likely to increase.

[Brief explanation of drawings]

FIG. 1 is a plan view showing a conventional choke coil, FIG. 2 is a current characteristic diagram showing the DC superimposed current characteristics of its inductance, and FIG. 3 is a perspective view of a choke coil according to the present invention.
FIG. 4 is an exploded perspective view of the same, and FIG. 5 is a current characteristic diagram showing the DC superimposed current characteristics of the inductance. 3a, 3b...magnetic material, 4a, 4b, 4c
, 5a, 5b, 5cm metal printed wiring, 6a, 6b
, 6c, 6a-1゜6b-1, 6cm1.6a-2
, 6b-2, 6cm2...Through hole, 11.1
2... Insulating plate, 14... High magnetic permeability material, 15...
...Insulating material.

Claims (1)

[Claims] first and second insulating plates, an insulating material sandwiched between the first and second insulating plates, and a first insulating material embedded in the insulating material.
and a second magnetic material, the first insulating plate has a first metal printed wiring to constitute a part of the winding, and the second insulating plate includes a first metal printed wiring for forming a part of the winding. a second printed metal wiring for forming a part of the insulating material, at least one of the first and second insulating plates has a printed metal circuit, and the insulating material forms a winding. The first magnetic material has a toroidal shape with a gap in a part of the cross section, and the second magnetic material has a through hole for electrically connecting the first and second printed metal wiring. A choke coil characterized in that a material is inserted into the gap of the first magnetic material, and the inductance due to the first and second magnetic materials increases significantly due to a reduction in DC superimposed current.