EP3910654A1 - Transformer with cylinder winding - Google Patents

Abstract

The invention relates to a transformer (1) having a first winding (11) and a second winding (12), the first winding (11) and the second winding (12) being arranged concentrically around a leg (2) of the transformer (1) . To improve the transformer (1), it is proposed that the first winding (11) comprises a first partial winding (21) and a second partial winding (22), the second winding (12) between the first partial winding (21) and the first winding ( 11) and the second partial winding (22) of the first winding (11) is arranged. The invention also relates to a method for operating a transformer (1) of this type, the transformer (1) being operated with currents and / or voltages with a frequency in the range from 100 Hz to 500 kHz. The invention also relates to a computer program product for simulating the operating behavior of such a transformer (1) in an electrical environment.

Description

The invention relates to a transformer with a first and a second winding, the first winding and the second winding being arranged concentrically around one leg of the transformer. The invention also relates to a method for operating such a transformer. The invention also relates to a computer program product for simulating an operating behavior of a transformer.

Transformers come in a variety of designs. They are used, for example, to generate a predeterminable voltage level, to connect different voltage levels with one another and / or to establish a galvanic separation between two areas. Depending on the application, transformers are operated at different frequencies. In power distribution networks often with 16 2/3 Hz, 50 Hz or 60 Hz. Medium-frequency transformers are used in the frequency range between 100Hz and 500kHz.

In general, transformers have a winding system with at least one primary and one secondary winding, as well as a core for guiding the magnetic flux. The part of the core around which the windings are arranged is called the main leg. Further legs run parallel to this, but they have no winding and are used for the return of the magnetic circuit. These are also referred to as return legs. Most of the legs are arranged parallel to one another. The legs, both main legs and return legs, are connected to one another via a yoke or a plurality of yokes in such a way that a closed circle is produced as a core for guiding the magnetic flux.

The core of the leg and yoke for guiding the magnetic circuit is formed, for example, from a ferrite that the magnetic Can guide and guide flow well and with little loss, without going into saturation.

The transformer described in more detail here has a cylinder winding. The winding system with its windings is then constructed in the shape of a cylinder. With two windings, the outer winding surrounds the inner winding in the radial direction. When cutting through these windings, concentric circles of the windings are created. The cylinder winding is therefore also described in that the windings are arranged concentrically around one leg.

The winding system with its two windings should be able to be produced independently of the magnetic circuit, so that only the winding system has to be connected to the magnetic circuit material during the production of the transformer.

A transformer that has a cylindrical winding and only windings are arranged around exactly one leg is also known as a round transformer. However, the winding system of a round transformer cannot be distributed to two or more legs via partial windings, so that the current to be transmitted only flows via one primary-side and one secondary-side winding. At most it is possible to wind several lines parallel to one another to form a winding system.

The invention is based on the object of improving a transformer, in particular a circular transformer.

This object is achieved by a transformer having a first winding and a second winding, the first winding and the second winding being arranged concentrically around a leg of the transformer, the first winding comprising a first partial winding and a second partial winding, the second winding is arranged between the first partial winding of the first winding and the second partial winding of the first winding. Further this task solved by a method for operating such a transformer, wherein the transformer is operated with currents and / or voltages with a frequency in the range from 100 Hz to 500 kHz. The object is also achieved by a computer program product for simulating an operating behavior of such a transformer in an electrical environment.

Further advantageous refinements of the invention are given in the dependent claims.

The invention is based on the knowledge that a transformer with a cylindrical winding can be improved by splitting a first winding into two partial windings and these partial windings encompassing the second winding of the transformer from inside and outside as seen in the radial direction. This results in a build-up of the winding from the inside, starting at the leg, to the outside, i.e. with an increasing radius from the first partial winding of the first winding, followed by the second winding. This is then followed by the second partial winding of the first winding. This division minimizes the interactions between the two windings in such a way that the current displacement has a uniform effect on the first winding and the second winding. The same effective cross section can thus be used for the conductors of the first and the second winding. The conductor is formed, for example, by a line or a wire which is arranged wound around a leg in a cylindrical shape. A winding can be formed by several parallel lines to increase the effective cross section. The effective cross-section results, among other things, from the number of parallel lines in the winding. The current displacement due to the magnetic coupling increases the resistance of the conductor. This means that in the proposed arrangement, due to the low current displacement, the same number of parallel lines can be provided for the first and the second winding, and thus the same resistance results in the windings.

In particular, when the transmission ratio is equal to 1, the number of parallel lines for producing the winding or the effective line cross-section of the respective windings can be selected to be the same, since in this case the same current flows in the windings. If the transmission ratio is not equal to 1, it has proven to be advantageous to select the number of lines of the respective windings or the effective cross-sections of the lines in the ratio of the transmission ratio, since the losses are then evenly distributed over the windings. This ensures that only a smaller cross-sectional area is required on the high-voltage side, where a lower current flows.

Overall, regardless of the transformation ratio of the transformer, dividing the first winding into two partial windings leads to better utilization of the copper, since the current displacement in the individual lines of the winding system, i.e. in the individual lines of the windings, is sometimes significantly reduced. In other words, despite the use of less conductor material, the electrical resistance for the conductor can be reduced. Due to the lower requirement for copper, the transformer is not only lighter, but also in some cases significantly cheaper. The windings are also smaller in terms of installation space, so that the core of the transformer is also smaller, lighter and more cost-effective. Due to its smaller size, the transformer can therefore also be more easily integrated into different applications.

Since the effect of current displacement in the line of the windings becomes more noticeable with increasing frequency in the form of the skin effect, a transformer constructed in this way is particularly suitable for use in the medium frequency range, i.e. frequencies in the range from 100 Hz to 500 kHz. These medium-frequency components have a particularly strong effect on the current displacement in the conductor. Without dividing the first winding into two partial windings for low-loss operation for the outer winding of the cylinder winding, even with a transmission ratio of one, a multiple of electrically parallel lines is provided in order to enable low-loss operation. Due to the large radius of the outer winding, such a transformer would become disproportionately expensive if one wanted to transform or decouple voltages / currents in the medium frequency range with this transformer, such as galvanically isolating them.

The proposed transformer with the division of the first winding into two partial windings, which, viewed radially, surround the second winding from inside and outside, also has the advantage of uniform heating. In addition, cooling air can also be guided between the respective partial winding and the second winding. The transformer can also be cooled significantly better through these additional cooling air paths. Furthermore, by reducing the current displacement and thus improving the electrical resistance of the windings, the heating of the winding and core is also improved, i.e. reduced, and thus makes it possible to save both copper and magnetic material. The simple geometry of the winding arrangement also allows time to be saved during manufacture.

Due to the lower parasitic effects, the operating behavior can also be simulated more easily and, above all, more precisely. By integrating a model for the transformer, the operating behavior of an entire system can be precisely examined, calculated and observed. The electrical environment refers to components with which the transformer is in electrical interaction. These are, for example, electrical consumers that are supplied with electrical energy from a source via the transformer or electrical consumers that are operated in parallel on one winding of the transformer.

In an advantageous embodiment of the invention, the first partial winding and the second partial winding of the first winding are arranged electrically in parallel. The parallel connection has a particularly positive effect on the stray fields between the two windings and thus on the interactions between the two windings. By connecting the two partial windings in parallel, which then results in an effective cross-sectional area that is twice as large as that of a single partial winding, the current displacement effects in the lines, in particular in the lines of the second winding, are in some cases significantly reduced. The second winding can then be designed with the same effective cross-sectional area as the first winding, in particular with a transmission ratio of 1.

In a further advantageous embodiment of the invention, the effective line cross-sections of the first winding and the second winding differ depending on the transmission ratio. Especially in the event that the transformation ratio is not equal to one, i.e. the transformer is at least not used exclusively for galvanic decoupling, the windings differ in the high-voltage and low-voltage side. Different currents can be observed on the high-voltage side and the low-voltage side. Due to the current displacement effect, the resistance in the relevant line increases. This resistance has a direct effect on the losses in the winding, which are noticeable through heat. It has thus proven advantageous to provide a higher effective cross section on the low voltage side, for example by using several parallel lines. In addition to dividing the first winding into two partial windings, the loss behavior can thus be improved even further. The measure of the further parallel line is also particularly effective, since, due to the division of the first winding into two partial windings, the cross-section of the additional lines is much more effective for improving the loss behavior. There is little or no skin effect is present, the entire introduced cross-sectional area of the line is effectively used for current conduction. In particular, the ratio of the effective cross sections of the lines of the first winding and the second winding can correspond to the transmission ratio or the square of the transmission ratio in an advantageous embodiment. A particularly even distribution of the losses and particularly good utilization of the copper in the lines of the corresponding winding can thus be achieved. In combination with the lower current displacement, a particularly low-loss and, moreover, light and inexpensive transformer can be produced, since the copper of the conductors or lines can be used particularly effectively.

In a further advantageous embodiment of the invention, the transformer has a transformation ratio of 1. Especially with a transmission ratio of 1, at which the windings do not differ in terms of high voltage and low voltage and thus the same currents flow, it is particularly advantageous to have the same effective cross section of the windings. This means that the losses are also evenly distributed over the windings, since the current displacement due to the division of the first winding between the two partial windings loads the first and second windings uniformly. In order to produce the same effective cross section, the number of parallel lines can be chosen to be the same for each winding in a simple manner. This enables the same effective cross section to be achieved in the first and second windings in a simple manner while saving on conductor material such as copper.

In this way, small and light transformers for electrical isolation can be produced in a particularly simple manner. These are particularly important for the integration of several different components, but rarely enough space is available. Thus, for the application of the integration of different components, such is the case Transformer is particularly advantageous because it can be used flexibly and in a space-saving manner.

In a further advantageous embodiment of the invention, the transformer has precisely one central main leg on which the first winding and the second winding are applied. For simple applications it is often sufficient to execute windings only around one limb, which is then referred to as the main limb. By saving on parallel lines, especially for the second winding, the windings are each smaller in size and can therefore then be applied to only one leg or attached or arranged on only one leg. This also makes transformers of this type particularly small in size. It is also possible to use material with lower magnetic conductivity for the core, since the path of the magnetic flux in the core is sometimes significantly shorter and thus lower losses occur even with inexpensive core material.

In a further advantageous embodiment of the invention, the transformer has a plurality of return legs, which are evenly distributed on a circular path around the central main leg. The compact design makes it possible to provide several return legs, for example five or more, which are arranged uniformly on a circular path around the main leg. In this case, the yoke is then star-shaped. In this way, too, compact structures of a transformer can be produced, which can ensure high levels of efficiency even when using inexpensive materials. Due to the large number of return legs, these return legs can be dimensioned smaller than the main leg and thus, among other things, reduce the structural volume of the transformer.

FIG 1

einen Transformator mit Zylinderwicklung und

FIG 2, FIG 3

Ausführungsbeispiele eines Transformators in unterschiedlichen Schnittzeichnungen.

The invention is described and explained in more detail below with reference to the exemplary embodiments shown in the figures. Show it:

FIG 1

a transformer with cylinder winding and

FIG 2, FIG 3

Exemplary embodiments of a transformer in different sectional drawings.

the FIG 1 shows a transformer 1 with a cylinder winding as is known from the prior art. Two windings 11, 12 are produced and nested around a leg 2, the so-called main leg, of the magnetic circuit, ie arranged concentrically. The magnetic flux for coupling the two windings 11, 12 is guided in a core. The core has the leg 2, on which the windings are applied, also referred to as the main leg, the return legs 3, which are arranged parallel to the main legs, and the yoke 4, which connects the legs 2, both the main legs and the return legs 3, to one another on both sides, on. To avoid a current flow, the two windings are usually electrically separated from one another by an insulating element.

The inner winding has, for example, to ensure the required current-carrying capacity, two parallel lines that are wound around the leg. The outer winding is made up of four parallel lines, whereby two layers can be wound with two parallel lines. Due to the asymmetrical winding of the transformer 1, there is increased copper expenditure, since the magnetic fields of the primary and secondary windings have an unfavorable influence on one another and this leads to increased current displacement effects. The current displacement effects can be viewed as an increase in resistance in the individual lines, so that a higher line cross-section, as described above, for example through the use of several parallel lines, can or must be used to compensate for this increase in resistance. Even with one A transformation ratio of 1 is therefore provided for a different number of parallel lines and thus different effective cross-sections due to the current displacement for the two windings. The effect of current displacement is stronger the higher the frequency with which the transformer is operated.

the FIG 2 shows a section through the proposed transformer 1. The first winding 11 is formed by a first partial winding 21 and a second partial winding 22. These two partial windings 21, 22 radially surround the second winding 12 of the transformer 1. The resulting magnetic field between the windings 11, 12 or partial windings 21, 22 largely avoids current displacement effects and the two windings 11, 12 also operate during operation approximately the same electrical resistance.

Furthermore, the star-shaped yoke 4 closes the magnetic circuit, which results from a centrally arranged leg 2 and five return legs 3. In these sectional drawings, the leg 2, to which the windings 11, 12 are attached, and the yoke leg 3 are covered by the yoke 4 and are therefore not visible, but only indicated by the reference symbols. The legs 2 and return legs 3 of this arrangement are in another section through the transformer 1 of FIG 3 clearly visible.

It has also proven to be advantageous if an insulating material 6 is arranged between the partial windings 21, 22 and the second winding 12 in order to reliably avoid an undesired flow of current between the windings 11, 12 and the partial windings 21, 22 and a galvanic To ensure separation.

the FIG 3 shows a further section through the proposed transformer 1. To avoid repetition, refer to the description FIG 2 and those introduced there Reference numerals referenced. The first partial winding 21 and the second partial winding 22, which form the first winding 11, surround the second winding 12. These are arranged in a circle around the leg 2, with the cylindrical windings 11, 12 and partial windings 21, 22 concentric around this leg 2 are arranged and the partial windings 21, 22 surround the second winding 12 in the radial direction. The closed magnetic circuit is formed by the main leg 2, the yoke leg 3 and the yokes 4, which connect the main leg 2 and yoke leg 3 to one another on both sides. In addition to the return leg 3 shown on the left-hand side, the transformer 1 can also have further return legs 3. This is indicated by the cut edge at yoke 4 on the right-hand side of the figure. In particular, the transformer 1 can use the five in FIG 2 Have shown return leg. The yoke legs 3 can advantageously be evenly distributed on a circular path around the main leg 2.

In addition, the lines 5 of the windings 11, 12 or the partial windings 21, 22 are shown. Each layer represents a line that is wound around the leg 2. It can thus be clearly seen that the first partial winding 21 and the second partial winding 22 each have a line 5, which are preferably arranged electrically in parallel, while the second winding 12 has two lines which are arranged radially one above the other.

Both the lines of the two partial windings 21, 22 and the two lines of the second winding 12 are advantageously connected in parallel Windings 11, 12 result in the same equivalent resistance or at least an almost identical equivalent resistance which differs by a maximum of 5%.

The increase in the effective line cross-section, as is customary from the prior art for transformers with cylinder windings, can be avoided by dividing one of the two windings 11 into two partial windings 21, 22, in particular in the case of the present transformer 1, which is also referred to as a round transformer and these two partial windings 21, 22 enclose the second winding 12 on both sides. This is what they show Figures 2 and 3 . The three winding elements now required can still be manufactured individually and then connected to the magnetic circuit.

In summary, the invention relates to a transformer having a first winding and a second winding, the first winding and the second winding being arranged concentrically around a leg of the transformer. To improve the transformer, it is proposed that the first winding comprises a first partial winding and a second partial winding, the second winding being arranged between the first partial winding of the first winding and the second partial winding of the first winding. The invention also relates to a method for operating such a transformer, the transformer being operated with currents and / or voltages with a frequency in the range from 100 Hz to 500 kHz.

Claims (9)

Transformer (1) having: - a first winding (11) and - a second winding (12), wherein the first winding (11) and the second winding (12) are arranged concentrically around a leg (2) of the transformer (1), characterized in that the first winding (11) has a first partial winding (21) and a second partial winding ( 22), the second winding (12) being arranged between the first partial winding (21) of the first winding (11) and the second partial winding (22) of the first winding (11). Transformer (1) according to claim 1, wherein the first partial winding (21) and the second partial winding (22) of the first winding (11) are arranged electrically in parallel. Transformer (1) according to one of Claims 1 or 2, the effective line cross-sections of the first winding (11) and the second winding (12) differing as a function of the transformation ratio. Transformer (1) according to one of Claims 1 to 3, the transformer (1) being designed or provided for operation at a frequency in the range from 100 Hz to 500 kHz. Transformer (1) according to one of Claims 1 to 4, the transformer having a transformation ratio of 1. Transformer (1) according to one of Claims 1 to 5, the transformer (1) having precisely one central main leg (2) on which the first winding (11) and the second winding (12) are applied. Transformer (1) according to claim 6, wherein the transformer (1) has a plurality of return legs (3) which are arranged evenly distributed on a circular path around the central main limb (2). Method for operating a transformer (1) according to one of Claims 1 to 7, the transformer (1) being operated with currents and / or voltages with a frequency in the range from 100 Hz to 500 kHz. Computer program product for simulating an operating behavior of a transformer (1) in an electrical environment, the transformer (1) being designed according to one of Claims 1 to 7.

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