DE9111720U1 - Choke coil without core - Google Patents

Description

31 b J * ö &oacgr; Ut

Siemens AG

Choke coil without core
5

The invention relates to a choke coil without a core, consisting of a winding with &eegr; turns and a coil body.

Such coils with ohmic and inductive resistance are often used in electrical engineering. The name comes from the property of such coils to throttle (limit) alternating currents, whereby the degree of throttling depends on the number of turns of the choke coil and the frequency of the current.

At high frequencies the throttling effect is large, at low frequencies it is small, and with direct current there is no throttling effect at all. The throttling coil can be designed as an air coil or as a coil with an iron core. By applying the winding to iron the effect of the throttling coil can be significantly increased. In electrical power engineering, choke coils, usually without an iron core, are often used, e.g. to limit short-circuit currents in electrical systems, to maintain voltage in high-voltage lines, as smoothing chokes in rectifier systems, etc. The ohmic resistance of such coils is often negligible.

The arrangement of the windings on the coil body gives these coils their names. In a cylindrical coil, the winding is single-layered and consists of windings arranged close together. Such a cylindrical coil has the disadvantage that it has a relatively large external stray field. This stray field leads to transient electromagnetic interference (EMI) and, in a stationary manner, to eddy current heating in absorbing materials.

If the coil axis is circular and the winding start and end are close to each other, they are called toroidal coils.

Ur/Bim / 16.09. 1991

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also called toroids. A toroidal coil with an iron core of constant cross-section has no demagnetization factor and no dispersion.

Such a toroidal coil is used, for example, in a phase module of a mains converter and a drive inverter of a converter locomotive with a three-phase drive (magazine "ABB Technik", issue 10, 1990, pages 3 to 10). This phase module essentially consists of two turn-off thyristors (GTO thyristors) with their freewheeling diodes, protection and wiring elements.

Protection and circuit elements of a turn-off thyristor (GTO thyristor), also known as a snupper circuit, are known from the magazine "Hitachi Review", Vol.31, 1982, No.4, pages 173 to 178.

The disadvantage of such a toroidal coil is that the manufacturing process is very complex and this leads to high costs.

The invention is based on the object of specifying a choke coil without a core, also called an air coil, which has a low stray field and is easy to manufacture.

This object is achieved according to the invention in that a flexible cable is provided for the winding, that at least one carrier plate is provided as the coil body, the edge areas of which are provided with holes and the inner area of which is provided with an opening, and that the cable is guided through a hole and the opening per turn.

By using simple standard elements as parts of the choke coil according to the invention, the basic costs of a choke designed in this way are very low. The manufacturing process now consists of guiding a flexible cable of a predetermined length - length corresponds to η winding lengths - through a hole and the opening in the carrier plate until all holes guide the cable. This means that the

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The winding direction and the spatial arrangement are determined. The two free ends of this flexible cable are then provided with connection terminals, creating a choke that is ready for connection. This simple manufacturing process is not very complex and can be carried out by any production worker. In addition, this choke coil according to the invention has a low stray field, since this choke coil has a toroid-like design.

This gives you an inexpensive choke coil with low stray field without a core.

In an advantageous embodiment of the choke coil, the coil body consists of two carrier plates that are spaced apart from one another by means of predetermined spacers. The two carrier plates are identical. In this advantageous embodiment, the value of the inductance of this choke coil can be varied by changing the length of the spacer, which also allows an existing installation volume to be optimally utilized for this choke coil.

In a further advantageous embodiment of the choke coil, the opening in the carrier plate has an oval-shaped cross-section. Two edges of this opening run parallel to the narrow sides of the carrier plate and two edges are concave to the front sides of the carrier plate. Due to this oval-shaped cross-section of the opening in the carrier plate, the design of the choke coil increasingly resembles a toroidal design, which further reduces the stray field of this choke coil.

To further explain the invention, reference is made to the drawing, in which embodiments of the throttle according to the invention are schematically illustrated. 35

Figure 1 shows a choke coil according to the invention without a core, in Figure 2 an advantageous coil body of a choke coil according to the invention according to Figure 1 is shown in more detail and the

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Figure 3 shows another advantageous coil body of the choke coil according to Figure 1.

Figure 1 shows a choke coil according to the invention in detail. This choke coil without a core consists of a winding 2 and a coil body 4. The winding 2 consists of n windings 6, which consist of a flexible cable 8. A carrier plate 10 is provided as the coil body 4, which is shown in more detail in Figure 2. This design of the choke coil elements results in an air coil whose design is very similar to the toroidal design. This air coil therefore also has a low stray field.

Figure 2 shows a preferred coil body 4 of the choke coil according to Figure 1 in more detail. A carrier plate 10 is provided as the coil body 4, which is rectangular compared to the embodiment according to Figure 1. The edge areas of this carrier plate 10 are provided with holes 12, which advantageously follow the contour of an opening 14 in the interior area of the carrier plate 10. The diameter of each hole 12 corresponds to the diameter of the flexible cable 8 used in such a way that the flexible cable 8 can be easily guided through the hole 12, but the gap is kept small. So that the insulation of the cable 8 is not damaged when it is guided through or when it is mechanically fixed, the edges of each hole 12 are chamfered.

In this advantageous embodiment of the coil body 4, the opening 14 in the inner area of the carrier plate 10 has an oval-shaped cross-section. The edges of the opening 14 each run parallel to a narrow side 18 of the carrier plate 10 and the edges 20 of the opening 14 each run in an arc shape to an end face 22 of the carrier plate. The distance between the edge 20 and the end face 22 and the edge 16 and the narrow side 18 and thus the dimensions of the carrier plate 10 are determined by the bendability of the flexible cable 8 used.

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".-·' The oval-shaped opening 14 and the associated holes 12 result in an air coil whose design largely corresponds to the toroidal design. With this advantageous design of the coil body 4, the stray field is reduced even further.

Figure 3 shows another advantageous coil body of a choke coil according to Figure 1. This coil body 4 consists of two identical carrier plates 10 according to Figure 2, which are kept at a distance from each other by means of several spacers 24. By varying the length of the spacer, the value of the inductance of this choke coil can be changed. When using this advantageous coil body 4, the

Turns 6 of winding 2 oval-shaped. 15

Claims (4)

91 G 3 h 8 3 OE Protection claims 1. Choke coil without core, consisting of a winding (2) consisting of n turns (6) and a coil body (4), characterized in that a flexible cable (8) is provided for the winding (2), that at least one carrier plate (10) is provided as the coil body (4), the edge areas of which are provided with holes (12) and the inner area of which is provided with an opening (14), and that the cable (8) is guided through a hole (12) and the opening (14) for each turn (6). 2. Choke coil according to claim 1 with two carrier plates (10), characterized in that the two carrier plates (10) are spaced apart from one another by means of predetermined spacers (24). 3. Choke coil according to claim 1 or 2, characterized in that the opening (14) has an oval-shaped cross-section. 4. Choke coil according to claim 1, characterized in that insulating material is provided as the material of the carrier plate (10).