JPH03215911A - Variable inductor - Google Patents

Abstract

PURPOSE:To contrive improvement in controlling efficiency by a method wherein a magnetic gap is provided in the central part of the common magnetic leg of a grill type core, a control winding is provided astriding the two magnetic legs on the inside and a winding to be controlled is provided astriding an inside magnetic leg and an outside magnetic leg. CONSTITUTION:A control winding 11 is provided astriding two inside magnetic legs 6 and 7 among four magnetic legs using a grill type core 1, a winding 10 to be controlled is provided astriding the inside magnetic leg 7 and an outside magnetic leg located adjacent to the leg 7, and a magnetic gap 9 is provided in the central part of I-type cores 2 and 3. Accordingly, the magnetic gap 9 is formed on the magnetic circuit of the winding 10 to be controlled, but no magnetic gap is formed on the magnetic circuit of the control circuit 11, the core is saturated by the control current lower than that heretofore in use, and inductance can be reduced. Consequently, as the inductance can be reduced by a low current, the improvement in control efficiency can be achieved.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application (2) The present invention relates to a variable inductor used in a switching power supply or the like to control an output voltage or the like by changing the value of inductance.

One of the methods of controlling the output voltage of a conventional switching power supply is to use a variable inductor.

This is intended to control the output voltage by changing the inductance of the variable inductor, thereby changing the series impedance, parallel impedance resonance frequency, etc.

Variable inductors for this purpose have conventionally been shown in FIGS. 6 and 7. In FIG. 6, 60 is an eye-shaped core consisting of magnetic legs 65, 66, 67, and 68, a common magnetic leg 64 connecting these, and ■ a core 61; A non-magnetic film or the like was inserted between 67 and 68 as a magnetic gap 62. 63 is a control winding, and 69 is a controlled winding. As the control current flowing through the control winding 63 increases, the core becomes magnetically saturated and the inductance of the controlled winding 69 decreases. Regarding the coupling between the control winding 63 and the controlled winding 69, when the control current is zero, the coupling is zero, and even when the control current flows, the coupling is loose, so the controlled winding 69 The alternating current flowing through the inductor does not have a large effect on the control winding 63, so it is a convenient inductor in terms of circuit configuration.

In FIG. 7, which is another conventional example, 70 is 4
A three-dimensional core with a magnetic leg of a book, a flat common magnetic leg 71
．． 72 with magnetic legs 73, 74, 75, 76 and 7, respectively.
3', 74', 75', and 76' protrude, and the tips of the magnetic legs are connected to each other via a magnetic gap 77. Note that the magnetic legs 76 and 76' are hidden and not visible in the drawing. Control winding 7 is installed in magnetic legs 74.74' and 75.75'.
8 is the controlled winding 7 on the magnetic legs 73, 73' and 74.74'.
9 is wound.

Problems to be Solved by the Invention In the conventional example shown in FIG. 6 or 7, the magnetic gap was formed at the tip of each of the four magnetic legs. The purpose of the magnetic gap is to set the inductance of the controlled winding to a desired value. In other words, if there is no magnetic gap, the inductance of the controlled winding is
Since it is too large, a magnetic gap is inserted to reduce the inductance. However, since such a magnetic gap also exists as a magnetic gap in the magnetic path of the magnetic flux generated by the control winding, the magnetic resistance is high, and in order to magnetically saturate the core and reduce the inductance, the magnetic gap must be It was necessary to flow a larger control current than without, which was inefficient.

The present invention is intended to solve these problems, and aims to reduce inductance and improve efficiency with less control current.

Means for Solving the Problems In order to solve these problems, the present invention provides a magnetic gap in the center of the common magnetic legs of the eye-shaped core, and connects the control winding across the two inner magnetic legs. , 4 A controlled winding is provided across one inner magnetic leg and an adjacent outer magnetic leg.

Further, in a three-dimensional core having four magnetic legs, a magnetic gap is provided in the common magnetic leg, and the winding is performed so that this magnetic gap is inserted into the magnetic path of the controlled winding.

Effect With this configuration, a magnetic gap is formed in the magnetic path of the controlled winding, but no magnetic gap is formed in the magnetic path of the control winding, and the core can be driven with less control current than before. Since the inductance can be reduced by saturation, efficient control can be achieved.

Example Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a schematic diagram showing the configuration of a variable inductor according to an embodiment of the present invention. 1 is an eye-shaped core with magnetic legs 5 and 6
, 7.8, I-shaped cores 2 and 3 connecting these, and a common magnetic leg 4. ■-shaped cores 5 A 2 and 3 are rod-shaped and are joined to magnetic legs 5, 6, 7.8, and a magnetic gap 9 is provided at the abutting portion of the ■-shaped cores 2 and 3. This magnetic gap 9 is constructed by inserting a film or the like of a non-magnetic material. Reference numeral 10 denotes a controlled winding, which is wound across one magnetic leg 7 on the inside and one magnetic leg 8 on the outside. Reference numeral 11 denotes a control winding, which is wound across the two inner magnetic legs 6 and 7. 14.15 shows the path of the magnetic flux generated by the controlled winding 10,
Since these all pass through the magnetic gap 9, the inductance of the controlled winding 10 can be adjusted by changing the thickness dimension of the magnetic gap 9.

Reference numerals 16 and 17 indicate paths of magnetic flux generated by the control winding 11, and since none of these paths pass through the magnetic gap 9, the magnetic resistance is low. Therefore, inductance can be reduced with less control winding current than in the past. FIG. 5 shows this situation.

FIG. 2 is a perspective view of the variable inductor shown in FIG. 1 according to an embodiment of the present invention. The controlled winding 10 and the control winding 11 are wound around a bobbin 12 . 13 is a terminal.

FIG. 3 is a schematic diagram showing the configuration of a variable inductor according to another embodiment of the present invention. The difference from that shown in FIG. 1 is that the common magnetic legs 21, 22 and the magnetic legs 2526, 27, 28 are integrated. For this reason, the magnetic legs 26-2
Since the common magnetic legs 21 and 22 are inserted into the winding bobbin, the common magnetic legs 21 and 22 have the advantage of being difficult to shift and easy to assemble.

FIG. 4 is a perspective view showing a variable inductor according to another embodiment of the present invention. 57 is a three-dimensional core with four magnetic legs, 54, 55, 56. 57 are magnetic legs (57 is hidden from view), 50, 51.52 are common magnetic legs, common magnetic legs 51, 52 A magnetic gap 53 is provided between them. Reference numeral 58 denotes a controlled winding, which is wound across the magnetic legs 54 and 55, and 59 is a controlled winding, which is wound across the magnetic legs 55 and 56. The magnetic flux 7 generated in the controlled winding 58 passes through the magnetic gap 53, but the magnetic flux generated in the control winding 59 does not pass through the magnetic gap 53. Therefore, the inductance can be reduced with a smaller control current than in the past. can.

Effects of the Invention As described above, according to the present invention, inductance can be reduced with a smaller amount of current, which improves control efficiency and improves the efficiency of switching power supplies and the like.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a conventional variable inductor according to an embodiment of the present invention, and FIG. 7 is a perspective view of another conventional example. 1, 21... Eye-shaped core, 5, 6, 7.8,
8 25, 26, 27, 28. 25'
, 26' , 27'28', 54 55,
56.57... Magnetic leg, 23... I-shaped core, 4, 21, 22, 24, 50, 51.52...
...Common magnetic leg, 9,53...Magnetic gap, 1
0.58...Controlled winding, 11.59...
...Control winding.

Claims (2)

[Claims] (1) Using an eye-shaped core, a control winding is applied across the inner two of its four magnetic legs, and the inner one
A variable inductor in which a controlled winding is applied across a main magnetic leg and an adjacent outer magnetic leg, and a magnetic gap is provided in the center of an I-shaped core. (2) Using a three-dimensional core having four magnetic legs, a control winding is applied across two adjacent magnetic legs among the four magnetic legs, and one of the two magnetic legs is A controlled winding is applied across one of the magnetic legs and another adjacent magnetic leg, and a common magnetic leg is formed between the two magnetic legs around which the controlled winding is wound and the other two magnetic legs. A variable inductor with a magnetic gap.