GB2299714A

GB2299714A - Inductive component

Info

Publication number: GB2299714A
Application number: GB9607004A
Authority: GB
Inventors: Goesta Baarman
Original assignee: Nokia Telecommunications Oy
Current assignee: Nokia Oyj
Priority date: 1995-04-04
Filing date: 1996-04-03
Publication date: 1996-10-09
Anticipated expiration: 2016-04-03
Also published as: GB9607004D0; DE19614767A1; FI951603A; SE9601276D0; FI951603A0; GB2299714B; SE514888C2; FI102791B1; SE9601276L; FI102791B

Description

Inductive component 1 2299714

The present invention relates to an inductive component comprising a core made of magnetic material, a first group of windings comprising at least one winding, and a second group of windings comprising at least one winding, whereby the magnetic field produced in the core by the first group of windings is orthogonal to the magnetic field produced in the core by the second group of windings.

Inductive components having the operating principle of the type described above, particularly transformers, which utilize the basic theory according to which orthogonal electric fields permeating a core of magnetic material do not affect one another, are known in the German Patent 465 114, the German published application 24 587 and the U.S. Patent 4 210 859. Such cross flux inductances, in which two or three orthogonal magnetic fluxes are present, are applicable to situations which typically require two magnetic components that are to be implemented in as compact a manner as possible. Such situations emerge particularly in connection with power sources. However, problems with the prior art solutions described above are caused by the difficulties in implementing them in practice and the resulting high costs. The implementation of the winding operation, above all, causes problems.

It is an object of the present invention to introduce a new type of inductive component in which cross flux is utilized in a new kind of environment and by which the high production costs of the prior art solutions can be avoided. This object is achieved by the inductive component of the invention, which is characterized by the first group of windings comprising at least one winding implemented as printed wiring on a first circuit board,

2 the first circuit board having at least one hole for leading at least a part of the magnetic core through the board, the second group of windings comprising at least one winding portion implemented as printed wiring on a second circuit board, at least one winding portion implemented as printed wiring on a third circuit board, and means for connecting the winding portions of the second group of windings, which winding portions are implemented on the second and third circuit boards, into at least one winding of the second group of windings through the first circuit board and/or the magnetic core.

Thus, the basic idea of the invention is to implement the coils of the first winding, possibly the first transformer, as printed wiring on the first circuit board. Similarly, the windings producing a flux orthogonal to the magnetic flux of the first winding are implemented as printed wirings on two circuit board parzs, whereby an implementation that is relatively simple and economical as to production costs is achieved.

The magnetic core of the inductive component according to the invention advantageously comprises a first part and a second part, which at least for the most part are at opposite sides of the first circuit board.

If it is desired that the inductive component according to the invention is preeminently employed as a transformer, the embodiment especially well suited for this purpose is characterized in that the cross section of the first part of the core has an E-shape orthogonally to the plane of the first circuit board, and the cross section of the second part of the core is, in the same plane, rectangular, whereby the first circuit board has three essentially rectangular through holes for leading through the arms of the first part of the core. If it is also desired that the second, crossing, magnetic field constitutes a transformer construction, it is advantageous

3 for the center arm of the first part of the core and the point in the second part of the core that meets it to have holes for lead-through of the means that are used for connecting the winding portions of at least one winding of the second group of windings.

The inductive component of the invention can easily be electromagnetically shielded. Such an inductive component is characterized in that on the second circuit board surface facing away from the core there is provided fourth circuit board which is electrically connected to winding portion on the second circuit board in order to create a ground plane functioning as an electromagnetic shield. Naturally, a similar shield can be created on the other side of the component as well, whereby on the third circuit board surface facing away from the core there is provided a fifth circuit board which is electrically connected to a winding portion on the third circuit board in order to create a ground plane functioning as an electromagnetic shield. In practice, it is probably most advantageous to arrange the aforementioned ground planes on both sides of the component.

In the following, the inductive component according to the invention is described by an exemplary embodiment which in the accompanying drawing is illustrated as an exploded view.

In the exemplary embodiment of the drawing, there are illustrated the principal components of the inductive component of the invention: a first circuit board 4, a magnetic core consisting of parts 1A and 1B, and two circuit board parts 11 and 12. On the first circuit board, or the main circuit board 4, there are implemented as printed wiring 2 suitable coils for producing an appropriate inductive component for any one purpose. In the embodiment of the drawing, the coils 2 on the main circuit board 4 constitute a triple-column transformer.

4 is The coils implemented as printed wiring 2 for this specific purpose surround three rectangular holes 5, 6 and 7 provided in the circuit board. Each portion of the wiring 2 has a desired number of turns, i.e. each of them contain a desired number of narrow turns of printed wiring surrounding the holes 5, 6 and 7.

The two magnetic parts 1A and 1B provide the core for the aforementioned wiring 2. out of these two parts, the cross section of the part 1A has an E-shape orthogonally to the plane of the circuit board 4, and therefore comprises three arms, 8, 9 and 10, which are to be led through the holes 5, 6 and 7 in the circuit board 4. The second core part 1B to be applied from the other side of the circuit board 4 against the core part 1A is, in turn, a parallelepipedon shaped part made of magnetic material, which thus forms a kind of yoke against the Eshaped core 1A. When applying the parts 1A and 1B onto opposite si,'es of the circuit board 4, the wirings 2 surround the arms 8, 9 and 10 of the part 1A, and consequently form an almost conventional transformer structure wherein the direction in relation f rom the arm 8 to the 1B, and f rom the part closed route.

In addition to the flat planar transformer described above, the inductive component of the invention comprises a second group of windings which creates an electromagnetic f lux orthogonal to the f lux produced by the coils 2 on the circuit board 4. For this purpose, there are provided two circuit board parts 11 and 12, which contain coil portions 3A and 3B, respectively, implemented as printed wiring. The coil portions 3A on the circuit board part 11 begin from the connecting points 19 on the outer edge of the part, and terminate at the flux can pass in a perpendicular to the board 4, i.e. for example arm 9, and f rom there to the part 1B back to the arm 8 through a is connecting points 20 at the center of the part. Connecting parts or contact means 13, which project from the plane of the circuit board part 11 towards the core, are connected to the connecting points 19 and 20. There are similar coil portions 3B implemented as printed wiring on the surface of the circuit board part 12, and these coil portions, too, begin at the connecting points 21 at the outer edge of the part, and terminate at the connecting points at the center of the part. Contact parts or connecting means 14, cooperating with the contact parts 13 which are attached to the part 11, are coupled to these connecting points.

As illustrated by the drawing, the circuit board part 11 is introduced on the core part 1A, whereby the contact parts 13 projecting therefrom extend on the one hand through the through holes 22 provided in the circuit board 4, and on the other hand through the hole 15 at the center of the core part 1A. When introducing the circuit board part 12 onto the core part 1B surface which is facing away from the circuit board 4, the contact parts 14 therein meet the contact parts 13 on the circuit board part 11, whereby the contact parts form an electric connection. In order for this to be possible, the core part 1B naturally has a central hole 16, too, which has the same dimensions as the hole 15 of the part 1A. When the circuit board parts 11 and 12 are connected by the contact parts 13 and 14, one or more windings are created by the coil portions 3A and 3B. These windings circle the magnetic core formed by the core parts 1A and 1B, the magnetic core being circular from the point of view of the windings. When applying power through the coil portions 3A and 3B, at least one electromagnetic flux in the direction of the plane of the main circuit board 4 is produced in the core.

As shown in the above, the magnetic fields produced by the coils 2 and the fields produced by the coil

6 portions 3A and 32 are orthogonal, and therefore do not affect one another. In this way, a low integrated dualpurpose -nductance, which may e.g. be a transformer of a forward chopper and a coil, has been produced without an actual winding operation.

Screening around the transformer described above can simply be accomplished by using circuit board parts 17 and 18. These circuit board parts have a solid conductive foil layer. These circuit board parts are introduced onto the circuit board parts 11 and 12, and are electrically connected to a suitable portion of wiring on the circuit board parts 11 and 12. Like this, the circuit board parts 17 and 18 form ground planes around the inductive component of the invention and consequently shield it electromagnetically against external magnetic fields.

In the above, the inductive component of the invention is described by just one exemplary and rather complicated embodiment. It should be understood that the inductive component which is in accordance with the invention and which utilizes cross flux could be implemented with considerably simpler components, for example so that the magnetic core consists of one parallelepipedon part of magnetic material, placed in one hole of the main circuit board. The inductive components created under such circumstances may, e.g. be iron core coils. Therefore, the inductive component of the invention can be modified significantly as to its mechanical implementation, without departing from the scope of the attached claims.

7

Claims

1. An inductive component comprising a core made of magnetic material, a first group of windings comprising at least one winding, and a second group of windings comprising at least one winding, whereby the magnetic field produced in the core by the first group of windings is orthogonal to the magnetic field produced in the core by the second group of windings, characterized by the first group of windings comprising at least one winding implemented as printed wiring on a first circuit board, the first circuit board having at least one hole for leading at least a part of the magnetic core through the board, the second group of windings comprising at least one winding portion implemented as printed wiring on a second circuit board, at least one winding portion implemented as printed wiring on a third circuit board, and means for connecting the winding portions of the second group of windings, which winding portions are implemented on the second and third circuit boards, into at least one winding of the second group of windings through the first circuit board and/or the magnetic core.

2. An inductive component as claimed in claim 1, characterized in that the magnetic core comprises a first part and a second part, which at least for the most part are at opposite sides of the first circuit board.

3. An inductve component as claimed in claim 2, characterized in that the cross section of the first part of the core has an E-shape orthogonally to the plane of the first circuit board, and the cross section of the second part of the core is, in the same plane, rectangular, the first circuit board having three essentially rectangular through holes for leading through 8 the arms of the first part of the core.

4. An inductive component as claimed in claim 3, characterized in that the center arm of the first part of the core and the point in the second part of the core that meets it have holes for lead-through of the means that are used for connecting the winding portions of at least one winding of the second group of windings.

5. An inductive component as claimed in any one of claims 1-4, characterized in that on the second circuit board surface facing away from the core there is provided fourth circuit board which is electrically connected to winding portion on the second circuit board in order to create a ground plane functioning as an electromagnetic shield.

6. An inductive component as claimed in any one of claims 1-5, characterized in that on the third circuit board surface facing away from the core there is provided fifth circuit board which is electrically connected to winding portion on the third circuit board in order to create a ground plane functioning as an electromagnetic shield.

7. An inductive component substantially as hereinbefore described with reference to the accompanying drawing.