JPH02201908A - Inductance element - Google Patents

Abstract

PURPOSE:To acquire an inductance element of a simple structure which can vary inductance at a fast speed by varying an effective permeability of a magnetic circuit by an electromechanical coupling element. CONSTITUTION:A magnetic circuit of a coil 32 is composed of two U-shaped cores 34 and 35. A winding 36 is wound around the core 34 by a specified numbers. A piezoelectric element 38 of an electromechanical coupling element using piezoelectric effect is inserted between grooves 34B and 35B, and a side of the piezoelectric element 38 and the grooves 34B and 35B are bonded to form a gap 39 between legs 34A and 35A of the cores 34 and 35. A size of the gap 39 varies through expansion of the piezoelectric element 38 according to an applied voltage. Therefore, a magnetic reluctance in the coil 32 varies according to change of the gap 39 and an effective permeability also changes. An inductance L of the coil 32 can be changed in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to an inductance element, and is suitable for application to, for example, a switching regulator circuit.

B Summary of the Invention The present invention allows for variable control of inductance at high speed with a simple configuration by varying the effective magnetic permeability of a magnetic circuit using an electromechanical coupling element in an inductance element.

C. Prior Art Conventionally, some switching regulator circuits have been designed to maintain the secondary output voltage at a predetermined voltage by controlling the frequency of a driving power supply applied to a switching transformer.

That is, in FIG. 6, reference numeral 1 indicates a switching regulator circuit as a whole, in which commercial power is full-wave rectified by diodes 2 to 5, and then smoothed by a smoothing capacitor 6.

As shown in FIG. 7, the transistors 8 and 9 are connected in series and are supplied from the drive circuit 11 with drive signals S□ and Sb2 (FIG. 7(A) and ( B)).

Further, transistors 8 and 9 are adapted to receive smoothed power supply, so that drive signals SDI and SDI
During the period when the signal level rises, the transistors are turned on sequentially and alternately.

On the other hand, in the switching transformer 12, one end of the primary winding is connected to the connection midpoint of the transistors 8 and 9 via a coil 13 made of an inductance element, and the other end of the primary winding is connected via a capacitor 15. and is connected to the negative terminal of the smoothing capacitor 6.

As a result, in the switching transformer 12, when the transistors 8 and 9 are turned on alternately, a charging/discharging current flows in response to this, and a secondary voltage is induced in the secondary winding. .

Thus, in the switching regulator circuit 1,
The secondary voltage is rectified in both waves by diodes 17 and 18, and then smoothed by a smoothing capacitor 19 to obtain a secondary output voltage (■). . ,
It is designed to be output as .

On the other hand, the drive circuit 19 has a secondary output voltage VOt+T
and the corresponding secondary output voltage V. Drive signals SDI and Sfl! control the repetition period.

Thereby, in the switching regulator circuit 1, a secondary output voltage voteT maintained at a predetermined voltage is obtained.

D Problems to be Solved by the Invention By the way, if a small-sized smoothing capacitor 6 is used in this type of switching regulator circuit 1, the smoothing capacitor 6 occupies a large amount of the switching regulator circuit 1 as a whole. Therefore, it is thought that the entire switching regulator circuit can be downsized.

However, as shown in FIG. 8, if a small smoothing capacitor with a small capacitance is used, the transistor 8
A ripple is superimposed on the t source voltage V's (FIG. 8(A)) applied to the t source voltage V's, and the power source voltage VIN begins to pulsate.

Therefore, in the switching regulator circuit 1, there are two large output voltages V with respect to the pulsating power supply voltage VIN. In order to hold Ua at a predetermined voltage, drive signals SDI and 5L
The repetition period of lz must be variably controlled over a wide range, and if this continues, it will be difficult to stably drive the transistors 8 and 9.

Therefore, the inductance of the coil 13 is shown in Fig. 8 (B).
) may be varied in accordance with the pulsations of the power supply voltage VIN, and a method may be considered in which a voltage maintained at a predetermined peak value is applied to the switching transformer 12 even if the power supply voltage 1N pulsates.

In this way, not only can the transistors 8 and 9 be driven stably, but also the loss caused by the coil 13 can be reduced.
There is a problem that the inductance cannot be variably controlled so as to follow the 1.4 pulsation, and there is a problem that it cannot be practically applied to this type of switching regulator circuit.

On the other hand, as shown in FIGS. 9 and 10, a method of varying the inductance using a magnetic fluid may also be considered.

That is, in the coil 20, a non-magnetic cylinder 24 is disposed in the gap 23 of the core 22 around which the winding 21 is wound.

A magnetic fluid 25 is sealed within the cylinder 24, and the magnetic fluid 25 is moved within the cylinder 24 by operating a piston 26.

In this way, in the magnetic circuit of the coil 20, the magnetic resistance can be variably controlled depending on the position of the magnetic fluid 25, and in response, the inductance of the coil 20 can be variably controlled.

However, even with this method, there is a problem that it is difficult to variably control the inductance so as to follow the pulsations of the power supply voltage (2), and this method is still insufficient in practical use.

The present invention has been made in consideration of the above points, and aims to propose an inductance element whose inductance can be varied at high speed.

Means for Solving Problem E To solve this problem, the present invention provides an inductance element having a magnetic circuit (34, 35) and a winding 36 wound around the magnetic circuit (34, 35). At 32, the electromechanical coupling element 38 is used to connect the magnetic circuit (34,
The inductance L of the winding 36 is made variable by varying the effective magnetic permeability of the wire 35).

Using the F-action electromechanical coupling element 38, the magnetic circuit (34, 35
), the inductance L can be varied at high speed.

G example An embodiment of the present invention will be described in detail below with reference to the drawings.

(G1) First Embodiment In FIG. 1, in which parts corresponding to those in FIG. 6 are given the same reference numerals, 30 indicates a switching regulator circuit as a whole, which is compact and has a significantly smaller capacity than the conventional one. A shaped smoothing capacitor 31 is used to smooth the rectified power supply.

As a result, ripples are superimposed on the power supply voltage V, (7), and the peak value changes from 200 [V] to 100 (
V).

Furthermore, in this embodiment, a coil 32 as shown in FIG. 2 is used so that even if the power supply voltage VIN pulsates, a voltage maintained at a predetermined peak value is applied to the switching transformer 12. There is.

That is, as shown in FIG. 2, in the coil 32, 2
A magnetic circuit is constituted by two U-shaped cores 34 and 35,
The winding 36 is wound around the core 34 a predetermined number of times.

The legs 34A and 35A of the cores 34 and 35 have grooves 34B.
and 35B are formed.

On the other hand, the piezoelectric element 38, which is an electromechanical coupling element using a piezoelectric effect, is inserted between the grooves 34B and 35B, and the side surfaces of the piezoelectric element 38 and the grooves 34B and 35B are bonded to each other. , whereby a gap 39 is formed between the legs 34A and 35A of the cores 34 and 35.

Therefore, the size of the gap 39 is changed by expanding and contracting the piezoelectric element 38 in accordance with the applied voltage, and in this embodiment, the size of the gap 39 is 0.1 (mm) to 0. It is designed to vary within a range of .05 (mm).

Therefore, in the coil 32, the magnetic resistance changes in accordance with the change in the gap 39, and thereby the effective magnetic permeability changes, and the inductance L of the coil 32 changes.

In fact, even if the piezoelectric element 38 is driven at a relatively high frequency, it can expand and contract in accordance with the frequency.

Therefore, when the inductance L is varied by changing the effective magnetic permeability with the piezoelectric element 38 in this way, the inductance L can be varied by following the pulsations of the power supply voltage IN. .

Thus, in this embodiment, the gap 39 is 0.1
(mm) to 0.05 (oll), the inductance L of the coil 32 is 10 [μH] to
The number of turns of the winding 36 is selected so as to vary within a range of 20 [μH].

In response, the control circuit 40 outputs a drive signal to the piezoelectric element 38 via the amplifier circuit 41, thereby causing the power supply voltage V
The inductance L of the coil 32 is variably controlled according to IN.

Thereby, a voltage maintained at a predetermined peak value is applied to the switching transformer 12.

Thus, even if the power supply voltage VIN pulsates, the transistor 8
and 9 can be stably driven, and a switching regulator circuit 30 having a compact overall shape and high efficiency can be obtained.

According to the above configuration, the piezoelectric element 38, which is an electromechanical transducer, is arranged between the gap 39 and the effective magnetic permeability of the magnetic circuit is varied. Inductance can be varied.

Thus, a smoothing capacitor 31 with a small capacitance and a small shape
Since the voltage applied to the switching transformer 12 can be maintained at a predetermined peak value even by using the switching transformer 12, it is possible to obtain a switching regulator circuit which is compact in size as a whole and has high efficiency.

(G2) Second Embodiment As shown in FIG. 3, in this embodiment, instead of directly moving the core, a magnetic piece 46 is inserted between the gap 45.
is moved to variably control the inductance of the coil 47.

That is, in the coil 47, an E-shaped core 49 is arranged to face the E-shaped core 48, and the central legs 48A and 49B of the cores 48 and 49
A gap 45 is formed therebetween.

A bending element 51 is disposed on the top of the core 49, and one end of the bending element 51 is fixed to the end of the core 49 through a member 50.

The bending element 51 is made of a plate-shaped non-magnetic material, and a piezoelectric element 52 is disposed between the bending element 51 and the core 49.

As a result, in the bending element 51, the other end of the bending element 51 changes as the piezoelectric element 52 expands and contracts.
The attachment is such that it can be moved up and down using the member 50 as a fulcrum.

A cylindrical magnetic piece 4 is connected to the movable end of the bending element 51 via a rod-shaped support member 55 made of a non-magnetic material.
6 is attached, and the magnetic piece 46 passes through the through hole 49K of the leg 49A and faces the leg 48A.

Thus, in this embodiment, a magnetic circuit is formed by the cores 48 and 49 and the magnetic piece 46, and the other end of the bending element 51 moves up and down in accordance with the expansion and contraction of the piezoelectric element 52. The magnetic piece 46 is movable up and down, thereby making it possible to vary the effective magnetic permeability of the magnetic circuit.

In practice, if one end of the bending element 51 is used as a fulcrum and the other end is moved by the expansion and contraction of the piezoelectric element 52, the lever principle can be used to move the bending element 51, and the piezoelectric element 52 Even if the amount of expansion and contraction is small, the gap 45 can be largely varied.

Therefore, in the coil 46, even when the amount of expansion and contraction of the piezoelectric element 52 is small, the gap 45 can be made thick (variable).

On the other hand, J! of cores 48 and 49! ! 48A and 49
A winding 57 is wound around A a predetermined number of times.

Thus, by varying the gap 45, the inductance of the coil 46 can be varied.

According to the configuration shown in FIG. 3, the piezoelectric element 52, which is an electromechanical transducer, and the bending element 51 are combined to vary the effective magnetic permeability of the magnetic circuit.
Even when the amount of expansion and contraction of is small, the inductance can be greatly varied.

Thus, applied to a switching regulator circuit,
The same effects as in the first embodiment can be obtained, and the efficiency can be further improved.

(G3) Third Embodiment As shown in FIG. 4, in this embodiment, a bimorph 59 is used in place of the bending element 51 and the piezoelectric element 52 to vary the inductance of the coil 60.

In other words, the bimorph 59, which is an electromechanical transducer formed by laminating piezoelectric elements, is attached at one end to the core 49 using a member 50, and the magnetic piece 46 is attached to the other end via a support member 55. It is made so that it can be done.

Therefore, by applying a predetermined voltage to the bimorph 59, the magnetic piece 46 can be moved up and down, and the inductance of the coil 60 can be varied.

According to the configuration shown in FIG. 3, even if the bimorph 59 is used as the electromechanical transducer, the same effects as in the first embodiment can be obtained.

(G4) Fourth Embodiment As shown in FIG. 5, in this embodiment, a core 69 having the same shape as the core 49 is used in place of the core 48.

That is, in the coil 70, cylindrical magnetic pieces 71 are arranged vertically in the through hole 49 of the upper core 49 and in the through hole 69 of the lower core 69, thereby increasing the effective magnetic permeability. The inductance is made variable by changing the inductance.

According to the configuration shown in FIG. 3, even if cores 49 and 69 of the same shape are used, the same effects as in the first embodiment can be obtained.

(G5) Other Embodiments In the above-mentioned embodiments, an E-shaped core and a U-shaped core are used, but the shape of the core is not limited to this. For example, a coaxial core with equal area Cores of various shapes can be widely applied.

Furthermore, in the above-described embodiment, the case where the winding wire is wound around the central leg of the E-shaped core is described, but the present invention is not limited to this, and the winding wire can be wound around the legs on both sides of the central leg as necessary. It may be wound.

Furthermore, in the above embodiment, a piezoelectric element and a bimorph that utilize a piezoelectric effect are used as the electromechanical transducer, but the electromechanical transducer is not limited to this, and for example, a voice coil motor that utilizes a magnetic effect is used. A similar effect can be obtained by using an electromechanical transducer.

Furthermore, in the above embodiment, the case where the present invention is applied to the coil of a switching regulator circuit has been described, but the present invention is not limited to switching regulator circuits, but can be widely applied to various electronic circuits where the inductance of the coil is varied. can do.

Furthermore, in the above-mentioned embodiments, the case where the present invention was applied to a coil was described, but the present invention is not limited to a coil.
For example, it can be widely applied when varying the inductance of an inductance element, such as when varying the inductance of a switching transformer.

Effects of the Invention As described above, according to the present invention, by varying the effective magnetic permeability of the magnetic circuit using an electromechanical coupling element, it is possible to obtain an inductance element with a simple configuration that can vary the inductance at high speed. .

FIG. 1 is a connection diagram showing a switching regulator circuit according to an embodiment of the present invention, FIG. 2 is a perspective view showing a coil thereof, and FIG. 3 is a sectional view showing a coil according to a second embodiment.
FIG. 4 is a sectional view showing a coil according to the third embodiment;
The figure is a cross-sectional view showing a coil according to the fourth embodiment, FIG. 6 is a connection diagram showing a conventional switching regulator circuit, FIG. 7 is a signal waveform diagram explaining its operation, and FIG. 8 is an explanation of problems. FIGS. 9 and 10 are cross-sectional views of the coils used for explaining the signal waveforms.

13, 20, 3 Le, 21.36. 5...Gap, 69...Core, 3 ...Bimorph.

Deputy 2.47.60.70... Carp 57...
・Winding, 23.39.422, 34, 35, 48.49
．． 8.52...Piezoelectric element, 59...Eki Hitotanabe

[Brief explanation of the drawing]

Coil Fig. 2 M 2nd implementation I 1 83 Fig. Ne C

Claims (1)

[Claims] In an inductance element having a magnetic circuit and a winding wound around the magnetic circuit, the winding can be made by changing the effective magnetic permeability of the magnetic circuit using an electromechanical coupling element. An inductance element characterized by variable inductance of a wire.