JPH03217004A - Variable inductor - Google Patents

Abstract

PURPOSE:To obtain an inductor wherein adjustment can be performed to the optimum inductance automatically by a current flowing through a circuit in use by providing first and second windings that are wound around the same magnetic core in the reverse directions, and connecting one winding to the other winding through a series dropper in parallel. CONSTITUTION:First and second windings A and B which are wound around the same magnetic core in the reverse directions are provided. Either one winding of the first and second windings A or B is connected to the first winding A or the second winding B in parallel through a series dropper 11. For example, a coil 7 comprising the windings A and B which are wound in the reverse directions to each other and have common one end and a series dropper 11c comprising a transistor 9 which is connected to the winding B in series and a reference voltage forming circuit 10 which controls the base potential of the transistor 9 and controls a current flowing through the windings are provided. The winding A of the coil 7 is wound so that the required inductance is obtained at the time of the maximum-load impedance. The winding B is connected to the winding A in reverse polarities and wound so that the required impedance is obtained at the time of the minimum-load impedance.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a coil, and more particularly to a variable inductor whose inductance is varied by a current flowing through a series dropper.

[Conventional technology]

Conventionally, this type of variable inductor has been constructed by assembling a pot-shaped core provided with a cutout or an eccentric hole as shown in a or b in FIG. 2(A) or FIG. 2(B) as shown in FIG. Inductance is changed by rotating core 1 or core 3, but the inductance is changed by assembling cores 5 and 6 and screwing threaded core 8 into the center screw hole as shown in Figure 4. Ta.

[Problem to be solved by the invention]

The conventional variable inductor described above uses a manual inductance variable method using mechanical means, and thus has to be adjusted to a different desired inductance value for each circuit used. Furthermore, conventional inductors have a relatively narrow adjustment range.

Therefore, it is necessary to take adjustment time to adjust the desired optimum inductance value for each circuit used, and it is also necessary to use an inductor having an inductance suitable for each circuit used. Furthermore, the number of types of inductors inevitably increases, which is unreasonable from an economic standpoint.

Furthermore, even if the inductance value is once adjusted to the optimum value, if the additional impedance changes due to the temperature characteristics of the load, the inductance value will deviate from the optimum value for the load, and there is a risk that the characteristics of the load device may not be fully demonstrated.

An object of the present invention is to provide a variable inductor that uses a series dropper and whose inductance can be automatically adjusted to the optimum inductance depending on the current flowing through the circuit used.

[Means to solve the problem]

The variable inductor of the present invention includes first and second windings wound oppositely to each other around the same magnetic core, and a series dropper connected to one of the first and second windings.
The winding or the second winding are connected in parallel.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram showing one embodiment of the present invention.

Figure 1 shows a coil 6 consisting of windings A and B, which have one end common and are wound oppositely to each other, and a transistor 9 connected in series to winding B. The base potentials of transistors 9 and 9 are controlled to control the current flowing through the windings. A series dropper 11 consisting of a reference voltage generation circuit 10 to be controlled, an input terminal 12, a common terminal 13,
It is composed of an output terminal 14.

The winding A of the coil 7 is wound alone so as to obtain the required inductance at the maximum load impedance of the device connected to the output terminal 14. ! B is coupled with the opposite polarity to the winding A, and is wound so as to obtain the required inductance at the minimum load impedance of the device connected to the output terminal 14.

Winding B of coil 7 consisting of windings A and B wound in this way
As shown in Fig. 1, the series dropper circuit 11 is
are inserted in series, and windings A and B are connected in parallel with opposite polarities.

The reference voltage generating circuit 10 is set to operate so that the transistor 9 of the series dropper becomes non-conductive when the load impedance is maximum, and the transistor 9 becomes conductive when the load impedance is minimum.

When the load impedance is maximum, the series dropper
Since the transistor 9 of No. 11 becomes non-conductive, the current IB of the winding B is cut off, and only the current IA of the winding A flows, and the maximum inductance is inserted.

When the load impedance is minimum, transistor 1 becomes conductive, and currents IA and IB flow through both windings A and B.
The combined impedance of windings A and B is inserted.

When the load impedance is not at its maximum, the transistor 9 remains conductive, and the current 8 flowing through the winding B changes in accordance with the load impedance. Therefore, the magnetic flux of the winding B depends on the current IB, and cancels a part of the magnetic flux of the winding A to vary the inductance.

Therefore, the optimum inductance value is set in response to changes in load impedance.

In the above explanation, the input voltage of the reference voltage generation circuit 10 of the series dropper 11 is inputted from the output terminal 14 side, but it goes without saying that similar results can be obtained by inputting it from the input terminal 12 side. .

〔Effect of the invention〕

As explained above, the present invention controls the magnetic flux generated by one winding of a pair of coils that are reversely wound and connected in parallel to the series dropper connected to the other winding, and controls the current flowing through the series dropper connected to the other winding. By varying the magnetic flux generated in the wire, the desired optimum inductance can be set at any time.

Furthermore, the desired inductance can be set over a wide range simply by controlling the current of the series dropper, which is not only economical as fewer types of coils are used, but also the cores used do not require a special structure and can be used freely. This has the effect of allowing you to select a core with a different shape.

[Brief explanation of drawings]

Figure 1 is a block diagram showing one embodiment of the present invention, and Figure 2 (
A) and (B) are perspective views of conventional pot-shaped cores, Figures 3 and 4.
The figure is a perspective view of an inductor using a conventional pot-shaped core. 6 1-6...Core, 7...Coil, 8...Screw type core, 9...Transistor, 10...Reference voltage generation circuit, 11...Series dropper, 12...Power supply Input terminal, 13... common terminal, 14... power output terminal.

Claims (1)

[Claims] first and second windings wound oppositely to each other around the same magnetic core;
A variable inductor characterized in that the first winding or the second winding is connected in parallel to one of the first and second windings via a series dropper.