SI25571A - Performance of the transformer - Google Patents

Abstract

The transformer assembly with an output rectifier (30) comprising at least one primary winding (231), surrounded by at least one layer made with several wrappers, is placed at a suitable distance around the transformer axis (300), the iron core (236) electrically isolated from of said primary winding, at least one secondary winding (233) electrically isolated from said primary winding and said iron core comprising a first portion of said at least one secondary winding and said second portion of said at least one secondary winding, wherein both located at appropriate distances around the transformer axis (300) between which at least one primary winding is arranged, wherein said primary winding and said secondary winding overlap along the axis (500) in a part enclosed by the iron core and further, wherein said the primary winding and said secondary winding in the part of the windings of the windings which the said core core does not cling cover only partially or do not overlap, which enables the output rectifier connectors in the direction of the axis (500) to make a quick and short execution. As a result of the proposed transformer performance, the corresponding magnetic and electrical properties of the system are ensured, which provide a more homogeneous distribution of magnetic fields and a homogeneous distribution of electric currents in conductive parts, which affects the reduction of losses in the transformer and the increase in the power supply capacity of the primary side of the transformer with higher frequency voltages. The implementation of the secondary coil according to the present invention, however, enables the simpler production of the water cooling of the welding transformer with the production of holes of the corresponding dimensions.

Description

PERFORMANCE OF THE TRANSFORMER

Field of technique

Electrical engineering; transformers; dc-dc converters

Technical problem

The technical problem solved by the present invention is to provide a homogeneous distribution of the electric current in the windings of the transformer and the connecting elements, providing a sufficiently large surface on the side of the secondary winding, which is intended to connect the output rectifier and the connection of cooling, as well as to reduce the length of the straight connecting elements, which can be achieved by proposing the partial overlap of the primary and secondary windings in the winding heads.

State of the art

The known embodiments of relatively large-scale point-welding point-welding welding systems used for joining sheet metal, among various applications in the manufacture of car bodywork, have a unified structure comprising an input ac-ac converter for supplying a single-phase transformer with one primary and one secondary winding split into two equal parts with a common center branch, which, by means of the corresponding connection of the two diodes in the output rectifier, sums the flow of the two secondary branches or portions to produce at the output a sufficiently large direct current for welding.

Existing systems for resistance point welding of high-power welding with one-way welding current can differ from each other, while the basic structure always includes an adequate voltage source, an input rectifier, a one-way bus, an inverter, a single-phase welding transformer with a primary and secondary winding, divided into two equal parts with a common branch at the center of the winding, and where the two parts of the secondary coil with two gantry elements in the form of the output rectifier are bound so that the one-way welding current at the output is the sum of two directed flows from the two parts of the secondary windings. The outputs of the input rectifier and the receiver can be different, as are the transformer versions, and the output rectifier versions may also be different. The primary side of the conventional welding transformer is usually supplied with a pulse width modulated pulse width modulation (PWM) with a constant period with a frequency of about 1 kHz, may be less or more, but for some reason it is up and down for limited reasons. Existing manufacturers of resistor-point welding systems for the output rectifier are used by one or, exceptionally, several diodes in each part, and the relatively large current on these diodes, due to the relatively large internal ohmic resistances, cause relatively large Joule losses. Large Joules losses also occur on intermediate connections between secondary windings and diodes, which reduces the efficiency of the entire system.

A commonly known fact is that with the increasing frequency of the PWM modulated power supply at the same power of the transformer it is possible to reduce the cross-sectional area of the core core of the transformer accordingly, which, due to the reduction in dimensions, automatically causes the corresponding reduction in the size of the windings and, consequently, the weight loss. It is also commonly known that, as the frequency of the supply voltage increases, the directed current at the output from the output rectifier decreases, which is analytically grounded in DPI 10.1109 / r / C2017.2711549, IEEE. In US 2014/0321184 Al, the inventors exploited the known fact and increased the frequency of the supply voltage to 10 kHz so that in order to achieve a large secondary current of 20 kA instead of one secondary winding with a center branch, the secondary winding was divided into ten parallel-linked windings with center branches, in that each of these ten secondary windings is built up of its own synchronous rectifier (SU), all ten secondary windings with center branches are indirectly connected in parallel with the outputs from the SUs connected in parallel. According to the claims in US 2014/0321184 Al, the increase in the number of parallel-connected secondary parts can either increase the value of the secondary current at the same frequency of the PWM modulated power supply or, if the unchanged value of the secondary current increases by increasing the parallel branches of the secondary parts, the frequency of the PWM modulated supply voltage, which enables a suitable geometric reduction of the transformer, thus also reducing the weight. The main disadvantage of the proposed concept in US 2014/0321184 Al is the increased complexity of the building, which affects the cost and reliability of operation, and allows operation at significantly higher frequencies of PWM modulated power supply voltages.

A similar embodiment of a transformer with a parallel binding of a plurality of secondary winding coils and one common output rectifier is used in EP 2 749 373 Al. In this case, a so-called sandwich structure is used, in which a large number of successively coupled coils of the primary winding are placed in such a way that the corresponding coils of the secondary coil are installed between them. This solution is very similar to the embodiment in US 7978040 B2 from the viewpoint of the sandwich of the winding structure of the transformer itself, but it comprises several parallel coils of the secondary winding. The characteristic of both embodiments is the coating of the coils of the primary and secondary windings in the direction of the axis, which is parallel to the direction of the magnetic flow in the core of the transformer. The main disadvantage of this solution is the different implementation of the coil connections with the so-called positive side and the coil with the so-called negative side of the secondary winding, causing a large difference in both sides and a very non-homogeneous current distribution on one side of the secondary winding. Said transformation with a single primary coil coil and two coils or two sides of the secondary coil, where the coils are concentrically arranged over each other, due to asymmetry causes unwanted electromagnetic behavior of the entire system.

A different way of covering the coils of the primary and secondary windings in the axis perpendicular to the direction of the magnetic flow in the core of the transformer is used in US 6 369 68 BI. The complete coating of the foil-derived coils of the primary coil with coils of the secondary winding is ensured, and the connection of the primary and secondary windings is carried out in a plane perpendicular to the direction of the magnetic flow in the core of the transformer. The disadvantage of said embodiment is a curved embodiment of connectors which form loops with parts of the windings and associated connecting plates, which increases the wasted inductance.

The weight of the transformer which is planned for operation at a certain frequency of the supply voltage can also be reduced by certain structural interventions in which the plate-like execution of the windings from the existing resistance point welding systems of US 7978040 B2 is replaced by cylindrical, that is, the tubular execution of secondary windings, as is practiced in EP 3 232 453 Al. The use of this tubular version of the secondary winding of the transformer due to good overlapping of the windings ensures excellent magnetic coupling between the individual windings of the transformer, which, in addition to reducing the transformer weight and better cooling, can also achieve better efficiency and improve the electromagnetic properties of the transformer, thus achieving higher dynamics of operation of the welding system. The poor quality of such windings is that, in order to ensure good overlapping of windings, it becomes increasingly demanding to make suitable connections for connecting the output rectifier. Due to the implementation of the connections, there is an extremely non-homogeneous distribution of currents in windings and connections, which is particularly disturbing at large values of secondary currents. One of the main disadvantages of the transformer with the output rectifier in EP 3 232 453 Al is therefore the implementation of secondary rectifier connections which, in the geometric sense, form part of the loops, which affects the increase of the corresponding dissipated inductance, but which have a predominant influence on the rate of increase and decrease of the welding current . The disadvantage is becoming more pronounced with the increase in the frequency of the supply voltage, which is why it results in an even more pronounced decrease in the welding current. Distribution of current in massive terminals for the output rectifier is very inhomogeneous at the nominal values of the welding currents, which additionally increases the losses.

Description of the new solution

The proposed embodiment of the transformer, with a combination of complete overlapping of the implemented windings in the region of the transformer window and the partial overlap of the windings carried out outside the transformer window in the region of the windings, shows a partially tubular structure, and enables the electrical connection of the output rectifier with the cooling system through an adequate number of straight connections with a sufficiently large surface, which makes it possible to ensure a homogeneous current distribution in windings and connections, and the smaller scattered inductances are smaller. Choosing the right number of straight links and their position allows shortening the paths for electrical currents, which reduces winding losses. Due to shorter paths and more appropriate arrangement of connections, cooling is also easier.

In the described way, using the complete covering of the primary and secondary windings in the area where this is due to the improvement of the electromagnetic properties of the transformation of the most necessary and partial overlap of the windings carried out in the area of the windings, the above presented technical problem of solving various current densities in different parts of the transformer and the problem of the lack of sufficient connection surfaces for the electrical connection of the output rectifier and the connection of cooling which, in the case of using full overlapping of the primary and secondary windings in EP 3 232 453 Al, represents a key technical limitation. By implementing a transformer with partial overlapping of the primary and secondary windings, a compact transformer is achieved which enables the achievement of a homogeneous current distribution in all parts of the transformer, as well as shortening the connections and simple connection of the output rectifier with a sufficient cross-section of connections on one side and sufficient cooling on the other side, that it is possible to achieve the greater power of the transformer than in the cases enclosed by the state of the art.

The present invention relates to the implementation of a transformer in the sense of a different structure of the primary and secondary windings, whereby the implementation of secondary windings ensures complete overlap of the active parts of the primary and secondary windings in the part enclosed by the iron core, while in the part of the so-called heads of the primary and secondary windings, this overlap only partially, which makes it easier to implement connectors for the output rectifier elements, which at the same time become the element of each envelope forming a secondary winding. The modified version of the two winding wrapper enables the necessary change in the magnetic and electrical properties of the welding system, thus allowing the homogeneous distribution of electric currents in different parts of the transformer and consequently reducing the losses in the transformer, and increasing the ability to power the primary side of the transformer with higher frequency voltages. The implementation of the secondary coil according to the present invention at the same time enables a much simpler production of the aqueous cooling of the welding transformer by making sections of the straight cooling channels of the corresponding dimensions. With the implementation of cooling of smaller power transformers, cooling with coolant can be replaced by air cooling, which additionally simplifies the structure of the transformer.

The subject of the present invention relates to the improvement of the performance of suitably strong and robust electrical connections at suitable locations and the implementation of suitable cooling channels for cooling with liquid coolant media. The change in the transformer structure in accordance with the present invention reduces the technological complexity of the transformer making, and at the same time allows the integration of the terminal elements in the head of the two parts of the secondary winding.

The derating elements of the output rectifier can be diodes or transistors, due to relatively low voltages and high currents, preferably MOSFET transistors. Only two power diodes can be used, as is the case with existing industrial solutions.

The embodiment of the transformer according to the present invention provides a completely straight version of loops without connecting loops for connecting the output rectifier, which enables the reduction of associated inductances and provides a homogeneous flow distribution across the entire cross-section of the connections. In addition, these connectors are simply viable and short, which reduces electrical losses.

Performance of a transformer with partial overlapping of windings and a cooling system In the following, the subject of the invention is described by means of images, whereby the images form part of the patent application, and represent:

Fig. 1 according to the present invention shows a block diagram of the performance of existing high-power ac-dc converters.

Fig. 2 according to the present invention shows an electrical circuit diagram of existing transformers with an integrated output rectifier.

Fig. 3 according to the present invention shows a transformer structure with an integrated output rectifier.

Fig. 4 according to the present invention shows the structure of the transformer.

Fig. 5 according to the present invention shows the performance of a transformer with a cross-section view of A-A from Figure 4.

Fig. 6 according to the present invention shows the embodiment of the windings of Figure 4.

Fig. 7 according to the present invention shows the execution of a secondary winding of the transformers a. In the following, the invention is described by means of individual embodiments.

A block diagram of a resocable point welding system is shown in FIG. 1 and is denoted as a whole by number 100. The resocable point welding system comprises a voltage source 101, an input rectifier 102, a dipole connection portion with a filter 103, an input jumper 104, and a welding transformer with a built-in output rectifiers 105.

The transformer electrical circuit diagram of the transformer with an integrated output rectifier is schematically shown in Figure 2 and is as a whole designated by a number 200. The arrangement of the transformer includes a primary circuit 210 and seconds of a circuit 220 which are interconnected by means of a transformer 230. Primary coil 231 with the sheaths Ni the transformer 230 is connected to the primary circuit 210 and is supplied with the primary voltage ui 232. The secondary winding 233 has a N2 + N3 winding and is, according to the embodiment, composed of at least two identical segments 234 and 235, where, for the sake of equality, N3 = N2 is consequently equal. The primary and secondary winding of the transformer connects the iron core 236, which can be carried out differently. The primary voltage 232 is pulse width modulated, that is, a shorter PSM in different ways.

Secondary circuit 220 comprises two gantry elements 237 and 238, which can either be power diode or corresponding transistors, preferably MOSFET transistors. Both of the gantry elements 237 and 238 may also be carried out by parallel binding of several smaller diode or corresponding transistors, preferably MOSFET transistors, if large welding currents require this. In the secondary circuit 220 the points A1 239 are marked, the center branch A2 240 is connected to the point A6 244 by one of the load terminals on which the voltage is U2 245, the point A4 242, where the flow from the gantry elements 237 and 238, which with an additional connection leads to the point A5 243 for connection of the load.

The structure of the transformer with a built-in output rectifier to be shielded is shown in Figure 3, which is denoted as number 30 as a whole. In this case, the gate elements 237 and 238 of the output rectifier are embedded in the head of the first part of the secondary coil 234 and the head of the second part of the secondary coil 235 The first head of the secondary wrap 234 represents an element 239 with a gantry element 237 that is mounted between the 239 and the element on which the connection 243 is carried out and comprises the corresponding number of parallel-linked gantry elements in the form of power diode transistors, preferably MOSFET transistors. The first head of the secondary envelope 235 represents the element 241, hence, between the element 241 and the element on which the connector 243 is mounted, a grounding element 238 is installed, which comprises the corresponding number of parallel-linked gantry elements in the form of power diode transistors, preferably MOSFET transistors. In this case, parallel power magnets, transistors, preferably MOSFET transistors, which together represent the gantry elements 237 and 238, can also be replaced by only two power diode, as is the case with the conventional version of the system in US7978040 B2. Around the core core of the transformer, the primary winding 231 is installed. The secondary connections A5 and A6 are in relation to the position of the picture 3 above and below, and the seconds of the connection could be both lower or both at the top or at some other location. Similarly, the transformer, instead of two core 236, could also be implemented with a single core having the same cross-sectional area as the two cores 236 together, each of the two cores 236 comprising two C-segment segments.

All the windings in Figure 3 are electrically insulated with each other, and are also electrically insulated with iron j-ed 236.

Figure 4 shows the performance of a transformer that is subject to protection. The primary winding 231, as indicated in Figure 5, is made with a flat wire with a cross-section of axb, where a thickness b is a wire width concentrically positioned around the transformer axis 300. A secondary winding 233 is also located around the transformer axis 300, where are to the right and to the left of the axis 300 in places where the primary coil and the two secondary windings do not overlap completely, the well-visible attachments 234a, 234b, 235a and 235b, which allow simple connection of the output rectifier and the cooling, where round bores can be 410 designed for the flow of coolant. The embodiment of the transformer in FIG. 4 comprises four connecting points for the beginning and end of the two parts of the secondary winding 233, otherwise, it is also possible to make a transformer with at least one or more locations for connecting the output rectifier and the cooling. With the implementation of cooling of smaller power transformers, cooling with coolant can be replaced by air cooling, which additionally simplifies the structure of the transformer. All the windings in Figure 4 are electrically insulated with each other, and are also electrically insulated with iron j-ed 236.

Figure 5 shows the transformer from Figure 4 in cross-section A-A. In the present embodiment of the transformer, the primary winding 231 is divided into 3 layers, where the first layer lies at a distance of the rpl, according to the embodiment consisting of at least three types of wires, the second layer being at a distance of rp2, also in the embodiment consisting of at least three types of wires, the layer is located at the distance rp3, also in the embodiment, consisting at least of three types of wires, all of which are indicated in relation to the transformer axis 300. The thicknesses of the individual layers of the primary coil are pl, p2 and p3 and are in accordance with Figure 5, due to three types of wires in each layer, the same, but they could also be different if there were a different number of species.

Secondary winding 233 comprises two parts 234 and 235, wherein the first portion 234 is concentrically located around the transformer axis 300 at a distance rsl and the second part 235 at a distance rs2 around the transformers of the eighth axis 300. The extensions of the rectangular shape with cooling bores in portions 234a, 234b, 235a, and 235b are located at the distances hi, h2, h3 and h4 from the lower edge 430 in the direction of the axis 300 with the surface fx d.

In the described embodiment, in both parts of the secondary windings 234a, 234b, 235a, and 235b, empty spaces with the sizes xi x p3 and hi x p2 in which the second and third layer of the primary winding 231 are installed. Inside the two windows of the transformer 420 with dimensions jxh at a distance of the length of the iron core L along an axis 500 which is perpendicular to the axis 300, the first layer of the primary winding and both parts of the secondary winding completely overlap, and the second and third layer of the primary winding overlap with the first layer of the primary winding in full with the first and second while the secondary coil is partly coating the second and third layers of the primary coil, it is also perfect in five places, and in four places the overlap is limited, which enables a straight and short execution of the connectors of the output rectifier in the direction of the axis (500).

Parts of both parts of the secondary winding without overlapping in the expansion area in the transformer window in length L with bores 410 allow us to carry out the connections for the output rectifier and the cooling with the liquid.

The derivations of the rectangular shape in Figure 5 are the same, therefore d = sl = s2 = s3 = s4, but the dimensions can be completely different, only symmetry must be applied to the axis 300. In case of extreme choice when c = f, the extensions disappear and with them also holes for liquid cooling, and in this case cooling should be done differently, for example with air. The bores 410 are typically designed for liquid cooling, but can be used for screwing.

All windings in Fig. 5 are electrically insulated with each other, and are also electrically insulated with iron core 236.

Figure 6 shows a composite set of primary winding 231 and secondary winding 233 with separately marked parts 235a, 235b, 234a, and 234b, where four partial overlap zones between the primary and secondary windings in the right-hand side are clearly seen, which from the point of view of the operation of the transformer not relevant. It is important to ensure overlap in the remaining three-quarters of the windings of the primary and secondary windings. The primary winding is carried out with a rectangular wire a x b, and it could also be made with a round wire or wire, which includes parallel-connected circular wires or a combination of a rectangular wire cross-section a x b and a circular wire. All the windings in Figure 6 are electrically isolated from one another, and are also electrically insulated with iron core 236.

Figure 7 shows the first 234 and the second 235 parts of the secondary winding 233 with four extensions, which make it easy to connect the output rectifier and the cooling with the liquid. Although the individual parts of the first and second portions of the secondary windings 234 and 235 are drawn to include several parts, it is possible to produce both parts in a single piece, which significantly improves electrical properties. Figure 7 also shows the massive parts 700a, 700b of the two parts of the secondary coil 233, which are enclosed by the iron core along the axis 500 in the length of the iron core L, and at the same time ensure complete co-overlap of the windings in the described area. Similarly, the solid parts 700c provide complete mutual overlapping of the windings in the greater part of the head of the first and second parts of the secondary coil with Ig length, while in the smaller part of the heads the overlapping of the windings is only partially. All the windings in Figure 7 are electrically isolated from one another, and are also electrically insulated with iron core 236.

The values of measurements a, b, c, d, f g, h, j of Figure 5 are dependent on the desired output power of the transformer at the same cooling intensity, while the values of Z and e of Figures 4 and 5 depend on the frequency of the supply voltage on the primary winding.

The transformer (30) according to the present invention provides a homogeneous distribution of magnetic fields in the core core of the transformer (236), which reduces the occurrence of uncontrolled saturation of the iron core. The aforementioned embodiment of the transformer with the output rectifier also provides a homogeneous distribution of currents in conductive parts and a very short distance for connecting the output rectifier, which provides even slightly better system utilization than the proposed embodiment in EP 3 232 453 Al. With the proposed embodiment, it is also possible to achieve slightly higher output flow values under the same operating conditions.

The embodiment of the transformer in FIG. 4 shows a partial overlap of the primary winding (231) with a secondary winding (233) only in the winding heads on the left side of the transformer. Without changing the technical advantages of the proposed transformer performance, a similar system of limited overlap of the primary winding (231) with the secondary winding (233) can also be used for the winding heads on the opposite side, which is, according to Figure 4, on the left transformer. In this case, the extreme right-hand side member (238) of Fig. 3 can be moved to the opposite left side of the transformer, and the same embodiment of the overlapping of the primary and secondary windings along the axis 500 in length L, where the windings encircle the iron core 236, remain unchanged.

Claims (15)

PATENT CLAIMS A transformer (30) comprising: at least one primary winding (231) comprising at least one layer, each layer of the primary winding comprising a plurality of wrapped around the axis of the transformer (300), and each layer of the primary winding is positioned at a suitable distance from the axis of the transformer (300); an iron core (236) electrically insulated from said primary coil; at least one secondary winding (233) electrically isolated from said primary winding and said iron core, said iron core enclosing said primary and said winding seconds, comprising at least one layer of secondary winding (233), wherein each layer of the secondary winding comprises at least one wrap around the axis of the transformer (300) at the distance of the corresponding layer of the secondary winding from the transformer axis (300), wherein the first layer of the primary winding and the first layer of the secondary coil are in a certain total length along the axis (400) perpendicular to the axis of the transformer (300) do not overlap, or cover only partially, along the axis of the transformer (300), with the first layer of the primary and all layers of the secondary winding essentially overlapping along the axis of the transformer (300), each subsequent potential layer of the primary winding mounted in the direction of the axis (400) between the other possible layers of the secondary windings and wrapped around the axis of the transformer (300) at the distance of the corresponding coil layer from the transformer axis (300) or as the last layer in this way, if any other and any possible further layer of the primary winding does not overlap completely with the respective length of the secondary winding layer along the axis of the transformer ), which creates an empty space between the layers of any second and any further layers of the primary winding along the axis (400) in the same line, which gives an empty space for the implementation of short connections of the secondary layers of windings in the straight line along the axis (500). The transformer (30) according to claim 1, wherein the individual layer of the secondary winding in the free space sections can be expanded between any second or any further layer of the primary winding and forms a larger surface of the secondary windings connections for connecting the output rectifier. The transformer (30) according to claim 1, wherein the number of empty spaces for carrying ports in any second or each subsequent layer of the primary winding along the axis of the transformer (300) can be at least one or more, wherein the empty spaces are located at any distance from (430) along the axis of the transformer (300). Transformer (30) according to claim 1, comprising one primary winding (231) and a secondary winding electrically isolated from said primary winding and from said iron core, comprising a first part of said secondary winding and a second portion of said secondary winding, both of which located at appropriate distances around the transformer axis (300) between which at least one layer of said primary winding is installed, said primary winding and said secondary winding overlapping along the axis (500) in the part enclosed by the iron core and further, in wherein the coating of the first layer of the primary coil with two portions of the secondary winding in said part is complete, whereas the covering of the second and third layers of the primary coil with the first and second parts of the secondary coil remains complete only at those points, the two parts of the secondary winding being not widespread the extended part of the two parts of the secondary winding is overlapping with the other and the third part of the primary winding is limited, which enables the execution of short and straight connections along the axis (500) for the connection of the output rectifier and the cooling. The transformer (30) according to claim 1, wherein said primary winding and said secondary winding in the part of the windings of which the said iron core does not cling cover only partially or do not overlap. The transformer (30) according to claim 1, wherein the secondary coil (234) part (234) can be manufactured in one piece without joints, and wherein the secondary coil (235) portion (235) can be manufactured in one piece without joints. The transformer (30) according to claim 1, wherein the rectangular extensions with a surface f x d may be intended either to produce holes (410) for the flow of the coolant or for screwing. The transformer (30) according to claim 1, wherein the element (239) is connected to the straight outlet from the connecting terminals (235a) of the second part of the winding (233) without intermediate connections, which simultaneously represents the head on the right side of the second part (235) of the secondary windings (233) and part of the output rectifier. Transformer (30) according to claim 1, wherein elements (239) and (241) that are already part of the output rectifier are directly connected to the straight outlet from the terminal terminals of the two winding parts (233) and represent one of the secondary winding heads ( 233). Transformer (30) according to claim 1, wherein an element (240) is connected to the straight outlet from the terminal terminals of the two parts of the secondary winding (233), which represents the center branch between the two portions of the secondary winding. The transformer (30) according to claim 1, wherein, due to the correct rectangular shapes of the two secondary winding parts, it is possible to make straight bores (410) for the flow of the coolant. The transformer (30) according to claim 1, wherein both parts of the secondary winding (233) can also be produced without suitable extensions for performing cooling if the cooling of the transformer is not necessary. The transformer (30) of claim 1 may have coupled positions A 5 and A 6 at any one. The transformer (30) according to claim 1, wherein the primary winding may also be made with a circular wire or wire, comprising several parallel-coupled round wires or a combination of a wire with a rectangular cross-section a x b and a circular wire. The transformer (30) according to claim 1, wherein, using a similar system of limited overlap of the primary winding (231) with the secondary winding (233), even in the windings of the windings on the opposite side of the transformer, the migration element (238) is moved to the opposite side of the transformer, whereas the primary and secondary windings remain unchanged along the axis (500) in length L, the windings being enclosed by the iron core (236).