WO2021174275A1

WO2021174275A1 - Field-compensated coil

Info

Publication number: WO2021174275A1
Application number: PCT/AT2021/060074
Authority: WO
Inventors: Rainer SCALICK
Original assignee: Scalick Rainer
Priority date: 2020-03-06
Filing date: 2021-03-05
Publication date: 2021-09-10

Abstract

The invention relates to a coil (1), comprising a first winding (2) which is wound around a first core (3) and a second winding (4) which is wound around a second core (5), the windings (2, 4) having the same number of turns and opposing winding directions, and the cores (3, 5) being offset along a longitudinal axis (9) and are arranged substantially coaxially, the cores (3, 5) being electrically and magnetically isolated from one another. The invention also relates to a coil arrangement having at least one such coil.

Description

Field compensated coil

The invention relates to a coil according to the preamble of the independent claim, in particular a coil as an inductance in an electrical circuit, comprising two windings with opposite winding directions.

Coils with several windings are known in principle from the prior art. For example, AT 251 103 A shows a coil in which a first winding and a second winding with opposite winding directions are applied to a common iron core. The windings are spaced apart from one another in the axial direction of the iron core and are connected in series.

However, such coils suffer from unwanted stray fields that can disrupt surrounding devices through electromagnetic effects. Such interference emissions of electromagnetic radiation must be taken into account in the development of electrical devices, especially in critical applications such as switching regulators for automotive and telecommunications applications, in order to comply with the limit values of EMC (electromagnetic compatibility). Conversely, the spaced-apart windings lead to unwanted coupling (self-pollution) into the coil. It is therefore an object of the invention to solve this and other problems and to provide a coil whose magnetic field is protected as well as possible from external influences and emits magnetic stray fields as low as possible.

This and other problems are solved by a spool according to claim 1.

A coil according to the invention comprises a first winding which is wound around a first core and a second winding which is wound around a second core. The windings can be conventional insulated wires made of copper, aluminum or gold. The wire diameter of the two windings can be identical. The inductance of the windings is preferably identical. The windings can be substantially circular. The core can be a conventional iron core.

The windings have the same number of turns, but opposite winding directions. The cores are offset along a longitudinal axis and are arranged essentially coaxially to this axis. In this context, coaxial means arranged essentially symmetrically about a common axis.

According to the invention, the cores are magnetically and electrically isolated or separated from one another. As a result, oppositely directed magnetic fields are formed in the area between the cores, so that the magnetic stray fields essentially compensate each other in this area.

The two windings with their separate cores thus each have their own magnetic circuit and are only coupled by their stray fields. This separation of the cores according to the invention reduces the entire stray field of the coil and reduces EMC interference and interference signal coupling into the coil.

According to the invention it can be provided that the cores are magnetically and electrically isolated from one another by an insulating separating medium, in particular a separating layer. The separating medium can, however, also be an electrically and magnetically insulating housing of the cores; in this case it is not absolutely necessary to provide a separating layer.

A combination of housing and separating layer can also serve as an insulating separating medium. This ensures that the cores are isolated and spaced from one another.

According to the invention it can be provided that the separating medium or the separating layer has a thickness in the range of 0.01 mm or 0.1 mm to 50 cm, preferably 0.5 mm to 10 cm, particularly preferably about 1 mm, in order to provide adequate insulation of the kernels. The separating medium can be applied to the core or cores by sintering; in particular, it can be a ceramic layer. According to the invention it can be provided that the separating medium has an electrical conductivity of less than 10 ⁸ S / m, in particular 10 ¹⁶ S / m.

According to the invention it can be provided that the separating medium has a relative magnetic permeability m _G which is a factor of at least 10 less than that of the cores and in particular has a value of less than 1.5, for example m _G = 1 + 4 × 10 ⁷ .

According to the invention it can be provided that the separating layer is a ceramic, a resin, or an adhesive or comprises such a material. As a result, on the one hand, the requirement for a mechanical connection of the cores and, on the other hand, the requirement for an electrically and magnetically insulating layer is met.

According to the invention it can be provided that the windings of the coil are connected in series. For example, a desired inductance value can be achieved by connecting two coils according to the invention in series. According to the invention it can of course also be provided that the windings are connected in parallel. For example, a desired inductance value can be achieved by connecting two coils according to the invention in parallel. According to the invention it can be provided that the cores are made of ferrite, pressed powder or transformer sheet or comprise these materials. Due to the ferromagnetic properties of the materials mentioned, the required inductance of the coil can be selected for the application in question.

According to the invention it can be provided that the cores are dimensioned essentially the same. In other words, the dimensions of the cores and their material can be essentially the same. If the cores are constructed and dimensioned the same, practically complete compensation of the magnetic fields in the transition area can take place as a result of the same number of windings.

In embodiments of the invention, the cores can be designed as cylinder cores with essentially the same diameter and essentially the same length. The two cores are then offset from one another along their longitudinal axis. In this case it can be provided that the first core and / or the second core has a head-side collar, a foot-side collar and a web running between them, which has a smaller diameter than the two collars. The web can form a form-fitting receptacle for the first and second windings, which prevents axial displacement of the first and second windings. This axial securing of the windings enables a particularly compact and simple design of the coil.

It can in particular be provided that the head-side collars of the two cores are directed towards one another, so that the separating medium directly adjoins the two head-side collars. However, it can also be provided that the foot-side collars of the two cores are directed towards one another, so that the separating medium directly adjoins the two foot-side collars.

According to the invention it can be provided that the windings are connected via a turn deflector arranged in a transition area. The transition area can essentially correspond to the area of the separating medium. The windings can have winding ends that lead out of the coil and serve as electrical connections. According to the invention it can be provided that the head-side collars of the two cores are directed towards one another. In this case, it can be provided that the turn deflection connects the first winding in the area of the head-side collar of the first core with the second winding in the area of the foot-side collar of the second core, and the winding end in the area of the foot-side collar of the first core and the winding end in the Area of the head-side collar of the second core is led out.

According to the invention, however, it can also be provided in this case that the winding deflection connects the first winding in the area of the head-side collar of the first core with the second winding in the area of the head-side collar of the second core, and the winding end in the area of the foot-side collar of the first core as well the winding end is led out in the area of the foot-side collar of the second core.

In other embodiments of the invention, the cores can be designed as toroidal cores with essentially the same diameter and essentially the same rotational surface. In this case, the cores have the shape of a torus and are arranged offset from one another along a longitudinal axis. The longitudinal axis runs through the center points of the toroidal cores.

The invention also relates to a coil arrangement comprising at least one, in particular a plurality of coils according to the invention. Any desired inductivity can be achieved by connecting a large number of coil pairs in series or in parallel.

Coils or coil arrangements according to the invention can be soldered onto circuit boards in current or new designs, for example in SMD, THT, TFIR, hybrid, thick-film, thin-film construction or the like. Coils according to the invention can also be used in extensive floppy power transformers for infrastructure and floppy power applications. The coils can be made to any specification, including voltage, current, power, frequency, inductance, capacitance and resistive resistance. Further features according to the invention emerge from the claims, the description of the exemplary embodiments and the drawings.

Exemplary embodiments of the invention are explained in more detail below with reference to drawings. Show it:

1a shows a schematic three-dimensional representation of an embodiment of a coil according to the invention;

FIG. 1b shows a schematic side view of the embodiment from FIG. 1a;

2a shows an embodiment of a coil according to the invention with windings connected in series;

2b shows an embodiment of a coil according to the invention with windings connected in parallel;

Fig. 3 shows an embodiment of a coil according to the invention with annular cores;

Figs. 4a and 4b show further embodiments of coils according to the invention.

1 a shows a schematic three-dimensional representation of an embodiment of a coil 1 according to the invention. The coil 1 comprises a first winding 2 which is wound around a first core 3 and a second winding 4 which is wound around a second core 5. The first core 3 and the second core 5 are essentially cylindrical with the same diameter and the same length and are arranged coaxially along a longitudinal axis 9. The cores 3, 5 are thus essentially congruent along the longitudinal axis 9. In this exemplary embodiment, the windings 2, 4 are formed from copper wires with a diameter of approximately 2 mm and each have a number of turns of three. The cores 3, 5 each have a head-side collar 10a, 10a ', a foot-side collar 10b, 10b', which is approximately three times as wide in the direction of the longitudinal axis 9 as the head-side collar 10a, 10a ', and a web 10c running between them , 10c '. The two collars and the web are each connected to one another or in one piece. In other embodiments, the two collars can also have identical dimensions. The outer surface of the web 10c, 10c ‘is not in contact with the windings 2, 4 in the illustrated embodiment, since the inner diameter of the windings 2, 4 is greater than the diameter of the webs 10c,

10c 'is. The cores 3, 5 are designed identically, but separated from one another. A separating layer 6 is arranged between the cores 3, 5 and isolates them from one another. In this exemplary embodiment, the separating layer 6 is made of sintered ceramic and has a thickness, that is to say an extension in the direction of the longitudinal axis 9, of approximately 1 mm. The electrical conductivity of the separating layer 6 is very low in this exemplary embodiment, for example in the range of 10 ¹⁰ S / m. The magnetic permeability of the separating layer 6 is approximately equal to 1 in this exemplary embodiment.

In a schematically indicated transition area 8, the windings 2, 4 are connected to one another via a turn deflector 7. In the exemplary embodiment shown, the first winding end 11, the first winding 2, the winding deflector 7, the second winding 4 and the second winding end 12 are made from a continuous electrical conductor or copper wire.

The direction of winding of the first winding 2 runs in the opposite direction to the direction of winding of the second winding 4. In this exemplary embodiment, the first winding 2 is left-handed and the second winding 4 is right-handed. In other embodiments, not shown, this is the other way around.

In the transition area 8, the winding runs essentially parallel to the longitudinal axis 9 and a turn deflector 7 connects the first winding 2 to the second winding 4. In the embodiment shown, the winding ends 11, 12 also run parallel to the longitudinal axis in the area of the foot-side collars 10b, 10b ' 9. In other embodiments, the winding ends 11, 12 protrude in other directions. The head-side collars 10a, 10a ‘of the two cores 3, 5 are connected to one another at the end via the separating layer 6. The composite of the first core 3, insulating separating layer 6 and second core 5 forms a receptacle for the first and second windings 2, 4, which are positively mounted between the collars of the cores 3, 5 in order to prevent axial displacement of the windings 2, 4 .

In the transition area 8, a recess is provided both in the first core 3 and in the second core 5 on the head-side collars 10a, 10a 'and in the separating layer 6, through which the turn deflector 7 runs. The recess is approximately 1 mm larger than the diameter of the copper wires, so that the electrical conductor is not in direct contact with the cores 3, 5. The recesses of the cores 3, 5 and the recess in the separating layer 6 are essentially congruent. The recesses prevent the windings 2, 4 from twisting around the composite of the first core 3, insulating separating layer 6 and second core 5 by means of a form fit.

The head-side collars 10a, 10a ‘in contact with the separating layer 6 are designed with essentially the same diameter as the foot-side collars 10b,

10b ‘.

In the embodiment shown, the webs 10c, 10c ‘have a smaller diameter than the head-side collars 10a, 10a and the foot-side collars 10b, 10b‘. The mean diameter of the head-side collars 10a, 10a 'or the foot-side collars 10b, 10b' and of the webs 10c, 10c 'essentially corresponds to the mean winding radius of the windings 2, 4. The outside diameter of the windings 2, 4 is approximately in the illustrated embodiment 1 mm smaller than the diameter of the head-side collars 10a, 10a 'or the foot-side collars.

2a shows an embodiment of a coil according to the invention with windings connected in series. The first winding 2 and second winding 4 are connected to one another in series via the turn deflector 7, designed as a continuous copper wire. This embodiment also has all the features of the embodiment according to FIGS. 1a-1b, so that a further detailed description can be omitted.

2b shows an embodiment of a coil according to the invention with windings connected in parallel. The winding deflector 7 consists of two parts. The first part of the turn deflector 7 connects the end of the first winding 2 on the head-side collar 10a with the second winding end 12 and the second part of the turn deflector 7 connects the end of the second winding 4 on the head-side collar 10a 'with the first winding end 11. All other, not mentioned, features of the embodiment connected in parallel essentially correspond to the features of the embodiment of the series connection according to FIGS. 1 a - 1 b.

Fig. 3 shows an embodiment in which the cores 3, 5 are designed as toroidal cores or toroidal cores. The longitudinal axis 9 is the axis of rotation of the respective cores 3, 5. In the embodiment shown, the insulating housings 13, 13 'of the cores 3, 5, which are shown schematically, serve as the separating medium. In this illustration, the two toroidal cores are arranged on supports shown hatched. The first core 3 is encased by the housing 13 and the second core 5 by the housing 13 ‘. In this embodiment, the housings 13, 13 'are connected via an adhesive layer which forms a separating layer 6. In other embodiments, however, no adhesive layer is provided.

The first winding 2, here with a right-hand winding, has an opposite direction of winding to the second winding 4, here with a left-hand winding. In the embodiment shown schematically, the windings 2, 4 are connected in series via a turn deflector 7. In another embodiment, not shown, these are connected in parallel.

In an embodiment not shown, several coils according to the invention are interconnected to form a coil arrangement, for example two, three, four or five coils, each with two opposing windings.

Fig. 4a shows a further embodiment of a coil 1 according to the invention in a schematic side view. The coil 1 comprises a first winding 2, which is wound around a first core 3, and a second winding 4, which is wound around a second core 5, the windings 2, 4 having the same number of turns and opposite winding directions, and wherein the cores 3, 5 are offset along a longitudinal axis 9 and are arranged essentially coaxially to this. The cores 3, 5 are electrically and magnetically isolated from one another by a separating layer 6. The cores 3, 5 are designed as cylinder cores. The first core 3 and the second core 5 each have a head-side collar 10a, 10a ', a foot-side collar 10b, 10b' and a web 10c, 10c 'running between them. The head-side collars 10a, 10a 'of the two cores 3, 5 are directed towards one another and separated by a schematically indicated transition area 8. The windings 2, 4 are connected to one another via a turn deflector 7. The turn deflector 7 connects the first winding 2 in the area of the head-side collar 10a with the second winding 4 in the area of the foot-side collar 10b '. The winding end 11 is led out in the area of the base-side collar 10b of the first core 3 and the other winding end 12 in the area of the head-side collar 10a 'of the second core 5.

Fig. 4b shows a further embodiment of a coil 1 according to the invention in a schematic side view. The coil 1 comprises a first winding 2, which is wound around a first core 3, and a second winding 4, which is wound around a second core 5, the windings 2, 4 having the same number of turns and opposite winding directions, and wherein the cores 3, 5 are offset along a longitudinal axis 9 and are arranged essentially coaxially to this. The cores 3, 5 are electrically and magnetically isolated from one another by a separating layer 6. The cores 3, 5 are designed as cylinder cores. The first core 3 and the second core 5 have a head-side collar 10a, 10a ‘, a foot-side collar 10b, 10b‘ and a web 10c, 10c ‘running between them. The head-side collars 10a, 10a ‘of the two cores 3, 5 are directed towards one another. In a schematically indicated transition area 8, the windings 2, 4 are connected to one another via a turn deflector 7. The turn deflector 7 connects the first winding 2 in the area of the head-side collar 10a with the second winding 4 in the area of the head-side collar 10a ‘. The winding end 11 is led out in the area of the foot-side collar 10b of the first core 3 and the other winding end 12 in the area of the foot-side collar 10b ‘of the second core 5.

The invention is of course not restricted to the exemplary embodiments presented, but rather encompasses all coils and coil arrangements within the scope of the following patent claims. In particular, any core shapes and core designs are provided within the scope of the invention. List of reference symbols

1 spool

2 First winding

3 first core

4 Second winding

5 Second core

6 separation layer

7 turn deflection

8 transition area 9 longitudinal axis

10a, 10a ‘head-side collar 10b, 10b‘ foot-side collar 10c, 10c ‘web 11 First winding end 12 Second winding end

13, 13 ‘housing

Claims

1. Coil (1), comprising a. a first winding (2) wound around a first core (3), and b. a second winding (4) wound around a second core (5), wherein c. the windings (2, 4) have the same number of turns and opposite winding directions, and d. the cores (3, 5) are offset along a longitudinal axis (9) and are arranged essentially coaxially to this, characterized in that the cores (3, 5) are electrically and magnetically isolated from one another.

2. Coil (1) according to claim 1, characterized in that the cores (3, 5) are electrically and magnetically separated by an insulating separating medium, in particular a separating layer (6).

3. Coil (1) according to claim 2, characterized in that the separating medium is formed by electrically and magnetically insulating housing (13, 13 ‘) of the cores (3, 5).

4. coil (1) according to claim 2 or 3, characterized in that the separating medium has a thickness in the range of about 0.01 mm to 50 cm, preferably 0.5 mm to 10 cm, particularly preferably about 1 mm.

5. Coil (1) according to one of claims 2 to 4, characterized in that the separating medium has an electrical conductivity of less than 10 ⁸ S / m, in particular 10 ¹⁶ S / m.

6. Coil (1) according to one of claims 2 to 5, characterized in that the separating medium has a relative magnetic permeability p _r which is lower by a factor of at least 10 than that of the cores (3, 5) and in particular a value of less than 1.5, for example p _r = 1 + 4 x 10 ⁷ .

7. coil (1) according to any one of claims 2 to 6, characterized in that the separating medium is a ceramic, a resin, or an adhesive or comprises such a material.

8. coil (1) according to one of claims 1 to 7, characterized in that the windings (2, 4) are connected in series.

9. coil (1) according to one of claims 1 to 8, characterized in that the windings (2, 4) are connected in parallel.

10. Coil (1) according to one of claims 1 to 9, characterized in that the cores (3, 5) are made of ferrite, pressed powder or transformer sheet or comprise these materials.

11. Coil (1) according to one of claims 1 to 10, characterized in that the cores (3, 5) are dimensioned essentially the same.

12. Coil (1) according to one of claims 1 to 11, characterized in that the windings (2, 4) have essentially the same inductance.

13. Coil (1) according to one of claims 1 to 12, characterized in that the cores (3, 5) are designed as cylinder cores.

14. Coil (1) according to claim 13, characterized in that the first core (3) and / or the second core (5) has a head-side collar (10a, 10a '), a foot-side collar (10b, 10b') and a having a web (10c, 10c ') running in between, the web (10c, 10c') forming a form-fitting receptacle for the first and second winding (2, 4), which allows axial displacement of the first and second winding (2, 4) prevents.

15. Coil (1) according to one of claims 1 to 14, characterized in that the cores (3, 5) are designed as toroidal cores.

16. Coil (1) according to one of claims 1 to 15, characterized in that the windings (2, 4) are connected via a turn deflector (7) arranged in a transition region (8).

17. Coil (1) according to claim 16, characterized in that the windings (2, 4) have winding ends (11, 12) which are led out of the coil (1).

18. Coil (1) according to claim 16 or 17, characterized in that the turn deflector (7) the first winding (2) in the area of a head-side collar (10a) of the first core (3) with the second winding (4) in the area a foot-side collar (10b ') of the second core (5) connects, and the winding end (11) in the area of a foot-side collar (10b) of the first core (3) and the winding end (12) in the area of a head-side collar (10a') of the second core (5) is led out.

19. Coil (1) according to claim 16 or 17, characterized in that the turn deflector (7) the first winding (2) in the area of a head-side collar (10a) of the first core (3) with the second winding (4) in the area a head-side collar (10a ') of the second core (5) connects, and the winding end (11) in the area of a foot-side collar (10b) of the first core (3) and the winding end (12) in the area of a foot-side collar (10b') of the second core (5) is led out.

20. Coil arrangement comprising one or more coils (1) according to one of claims 1 to 19.