JPH06224052A - Transformer coil - Google Patents

Abstract

PURPOSE: To improve the degree of coupling between windings in a transformer having at least one first winding and one second winding. CONSTITUTION: A flexible litz wire 12 which consists of many individual wires having small cross-sections and being insulated mutually is wound into a coil. The individual wires are minutely twisted, or bundled. The first-coil and the second-coil are respectively formed of bundles 15, 16 and 17 consisting of a selectable number of individual wires.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to transformer windings having at least one primary winding and at least one secondary winding.

[0002]

BACKGROUND OF THE INVENTION In transformer windings, usually at least one primary winding and a secondary winding are wound one after the other on a transformer core or on a coil support or bobbin. The winding body concerned is subsequently inserted into the transformer core. Transformer windings are also known in which the conductors are first twisted together and subsequently wound around a transformer core or coil support. With this type of transformer winding, only a moderate degree of coupling is achieved between the primary winding and the secondary winding.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a transformer winding with improved coupling as described above.

[0004]

The transformer winding of the present invention having the structure described in the characterizing portion of claim 1 is, compared with the known transformer winding,
It has the advantage that a substantially ideal degree of coupling between the individual windings on the primary and secondary side is obtained, which results in a very good dynamics of the transformer with this type of winding. Characteristic arises. In particular, it should be mentioned here that the transformer has a low stray inductance. The manufacturing cost of the wound coil is low. This is because only one winding, the flexible litz wire, needs to be wound. If a bobbin or coil support is used, it can be a very simple structure. Due to the extremely small cross section of the individual wires and the large number of individual wires, a high copper occupancy can be achieved. The electrical isolation of the individual windings is ensured by the insulation of the individual wires, which is preferably realized as copper lacquer wire.

Advantageous embodiments and refinements of the transformer winding according to claim 1 are possible with the features of the other claims.

The conversion ratio between the primary winding and the secondary winding is 1:
If 1, then preferably 2 with the same number of individual wires
Two bundles are used, which guarantees the same current loading of the individual windings.

If a conversion ratio different from "1" is to be realized, then according to an advantageous embodiment of the invention at least 1 is obtained.
Two bundles are subdivided into strands having the same number of individual wires and the strands of this bundle are connected in series. The ratio of the numbers of strands connected in series in the bundle determines the transformation ratio between the windings constituted by the bundle. For example, when a flexible litz wire has 60 individual wires,
A transformation ratio of 1: 2 between the primary and secondary windings can be achieved by subdividing the litz wire into two bundles, each having 30 individual wires. The bundle forming the secondary winding is subdivided into two strands each consisting of 15 individual wires, and the two strands are connected in series. In that case, the transformation ratio ue = N1: N2 is 1: 2. This is because the secondary winding has twice the number of turns due to the series connection of two strands, each having 15 individual wires. Since the ratio of the currents I1 and I2 flowing through the windings in the transformer winding is inversely proportional to the winding ratio, the current I1 in the primary winding is twice as large as the current I2 in the secondary winding. In this case, on the basis of 30 parallel connected individual wires in the primary winding, it is possible to use a conductor cross section twice as large as in the case of a secondary winding with 15 parallel individual wires. it can. Therefore,
The current loads in the two windings are automatically of the same magnitude and are therefore optimally selected.

In an advantageous embodiment of the invention, at least one individual wire in a flexible litz wire is used as a shield winding. Basically, the shield winding can be connected arbitrarily. Advantageously, one connecting terminal is left unconnected, while the other connecting terminal is
Connected to ground, power supply or external element.

According to an advantageous embodiment of the invention, a high frequency litz wire is used as the flexible litz wire.
High frequency litz wire of this kind is known and used to reduce winding losses due to skin and proximity effects when using high frequencies.

The transformer winding according to the invention is universally usable and, owing to its very high degree of coupling, is particularly advantageous for power converters, HF-NF-transformers, pulse transformers or Cuk-converters. Can be used.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in detail with reference to the accompanying drawings with reference to the accompanying drawings.

The transformer shown diagrammatically in FIG. 2 comprises a three-legged transformer core 10 and a transformer winding 11 mounted on the central leg of the transformer core. At that time, transformer winding 11
Can be wound directly on the central leg or on a bobbin mounted on the central leg of the transformer core 10.

The coil-shaped transformer winding 11 is formed from a flexible litz wire 12, as shown in enlarged cross section in FIG. This flexible litz wire 12 includes a plurality of individual wire rods 13 each having a small cross-sectional area.
Made of. These individual wires are insulated from each other. Copper lacquer wire with a diameter of, for example, 0.1 mm is preferably used. Since the individual wire rods 13 are individually or a plurality of parallel individual wire rods 13 are gathered together and closely twisted with each other, the litz wire 12 looks outward to the observer as a uniform structure. In each case, the litz wire 12 is further coated on the outside with a silk fabric.

In the transformer shown schematically in FIG. 2, the transformer winding 11 has one primary winding and two secondary windings. In order to realize this transformer winding 11, a flexible litz wire 12 with a total of 90 individual wires is used. The 30 individual wires are each bundled into a bundle 15, 16 to 17, with one bundle 15
The secondary winding is formed and the bundles 16 and 17 form two secondary windings. Therefore, the transformation ratio of the transformer winding 11 is 1:
It is 1: 1.

The transformer winding 20 shown in FIG. 3 likewise has one primary winding and two secondary windings. 1
The transformation ratio of the windings between the secondary winding and the first and second secondary windings is selected to be 1: 2: 6. For this purpose a flexible litz wire with a total of 180 individual wires 1
2'is selected. The individual wire rod is divided into three bundles 21, 22 and 23, each of which is 60 individual wire rods. The bundle 21 with 60 parallel individual wires forms the primary winding. The two ends of the primary winding are connected to the terminals W11 and W12 of the terminal strip 24. The bundle 22 forms a first secondary winding and is divided into two strands 221 and 222 each of 30 individual wires. The two strands 221 and 222 are electrically connected in series, so that one terminal of the strand 221 is connected to the terminal W21 of the terminal strip 21 and the other terminal of the strand 222 is connected to the terminal 25. The strand 222 is connected to the terminal 26 at one terminal, and the strand 221 is connected to the terminal W22 at the other terminal. The terminals 25 and 26 are connected to each other by an electric conductor 27. The cross section of this conductor 27 is designed corresponding to the copper cross section of the strands 221 and 222. Terminals W21 and W
22 is the first 2 having twice the number of turns as the primary winding.
The connection of the next winding is formed. The bundle 23 forming the second secondary winding connection is divided into a total of 6 strands 231-236, each having 10 individual wires 13. All strands 231-236 are connected in series. The winding end of the second secondary winding connection is the end strip 2
4 terminals W31 and W32. Individual strands 231-236 are connected to terminals W31 and W32 and 41-50 in the manner shown in FIG. The terminals 41-50 have five conductors 35- in total.
They are mutually connected via 39. These conductors 35
The -39 cross section corresponds to 10 individual wires in 6 strands. Therefore, the second secondary winding is 1
It has six times the number of turns of the secondary winding and three times the number of turns of the first secondary winding. The cross section available for the current of the second secondary winding is 1/6 of the copper cross section of the primary winding and 1/3 of the cross section of the first secondary winding.
The cross section of the copper of the secondary winding is 1/2 of the cross section of the copper of the primary winding. Since the ratio of the transformer currents I1, I2, I3 flowing through the windings in the transformer is inversely proportional to the number of turns of the winding, the current load of all three windings of the transformer winding 20 is of the same magnitude, Therefore, it is automatically and optimally selected.

Terminals 25, 26 and 41-50 and conductors 27 and 35-39 are omitted and
Strand 22 connected to 26 and 41-50
It is of course also possible to connect 1 and 222 and 231-236 directly to one another. In that case, the terminal strip 24
Connection terminals W11 and W12 for the primary winding connection, the first two
W21, W22 and second 2 for the next winding connection
It has only terminals W31 and W32 for the next winding connection.

In order to shield the transformer winding 11 or 20, individual wires, which can be optionally connected, are used. Advantageously, one connection terminal is left unconnected, while another wire connection is connected to ground or an external element.

As a flexible litz wire 12 for producing the transformer winding 11 (FIG. 2) and the transformer winding 20 (FIG. 3), which is commercially available and used in high frequency applications, it is attracted by the skin effect and the proximity effect. High frequency litz wire known per se is used to reduce the winding losses caused.

The transformer winding 11 described so far is
It can be advantageously used in power converters, HF-NF-transformers, pulse transformers and so-called Cuk-converters. Cuk-converters or Cuk-converters have the advantage that, if the components are correctly selected, the output or input current of the converter or converter has almost no ripple characteristics. This allows the capacitance value of the input or output capacitors to be chosen significantly smaller than is customary for other blocking inverters. This saves construction space and costs and improves the radiation characteristics of the converter. With the transformer windings described above, the individual windings of the transformer are very well coupled to one another, so that the abovementioned advantages of the Cuk-converter can be fully utilized.

[Brief description of drawings]

FIG. 1 is an enlarged perspective view showing a part of a flexible litz wire with respect to a transformer winding.

2 is a schematic diagram of a transformer in which the transformer winding comprises the Litz wire of FIG.

3 is a schematic diagram of a transformer with a modified transformer winding consisting of the flexible litz wire of FIG.

[Explanation of symbols]

11,20 Transformer winding, 12 Litz wire, 13
Individual wire rods, 15, 16, 17; 21, 22, 23
Bundle, 221, 222, 231-236 Strand

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kai Kolberg, Germany Kiel Nerkenwerk 6

Claims (8)

[Claims] 1. A transformer winding having at least one primary winding and at least one secondary winding, comprising a number of small cross-section individual insulated wires (eg copper lacquer wire). A flexible litz wire (12) wound in the form of a coil, wherein the individual wire rods are individually or collectively bundled in parallel and closely twisted with each other, and Transformer winding, characterized in that each secondary winding is formed by a bundle (15, 16, 17; 21, 22, 23) of an arbitrarily selectable number of individual wires (13). 2. A bundle (15, 16,) of individual wires (13) constituting each winding (primary winding or secondary winding).
17. The transformer winding according to claim 1, wherein 17; 21, 22, 23) have the same number of individual wires. 3. At least one bundle (22,23) of individual wires (13) comprises strands (221,222,231).
-236) and the bundle (22,2)
3) the strands (221, 222, 231-23)
6. The transformer winding according to claim 1 or 2, wherein 6) is connected in series. 4. The ratio of the numbers of strands (221, 222, 231-236) connected in series in a bundle (22, 23) is such that the desired transformation of the windings formed by said bundle (21-23). 4. The transformer winding of claim 3 selected to be equal to the ratio. 5. Transformer winding according to claim 1, wherein at least one individual wire (13) is used as a shield winding. 6. The transformer winding according to claim 1, wherein a high frequency litz wire known per se is used as the litz wire. 7. The litz wire (12) comprises a transformer core (1).
0) Wound on 0), any one of claims 1 to 6
The transformer winding described in the paragraph. 8. The transformer winding according to claim 1, which is used in a power converter, an HF-NF-transformer, a pulse transformer or a Cuk-converter.