EP3763019A1

EP3763019A1 - Winding scheme for an electric machine

Info

Publication number: EP3763019A1
Application number: EP19703323.6A
Authority: EP
Inventors: Stefan Reuter; Matthias Ebert; Ralf Wittstadt; Andre Grübel; Christian Brückner
Original assignee: ZF Friedrichshafen AG
Current assignee: ZF Friedrichshafen AG
Priority date: 2018-03-08
Filing date: 2019-02-06
Publication date: 2021-01-13
Also published as: WO2019170350A1; DE102018203469A1

Abstract

The invention relates to a wave winding for an electric machine, wherein the wave winding has a number of holes of at least two, wherein at least three different variants of hairpins (6, 6', 6") are provided, wherein in a first variant of the hairpins (6) the turning region between the conductor elements has the standard winding pitch, in a second variant of the hairpins (6') the turning region has a second winding pitch which is greater than the standard winding pitch by a whole-numbered value x, and in a third variant of the hairpins (6") the turning region has a third winding pitch which is smaller than the standard winding pitch by a whole-numbered value, and in all three variants the contact regions are each shaped in the opposite direction to the turning region by half the standard winding pitch, in order to achieve the standard winding pitch between connected conductor elements of neighbouring hairpins (6, 6', 6"). The invention also relates to an electric machine and a stator (1) having a wave winding of this type.

Description

Winding diagram for an electric machine

The present invention relates to a winding scheme for an electrical machine and an electrical machine with a corresponding winding.

In the prior art, for example, DE 10 2014 223 202 A1 discloses that windings distributed in an electrical machine are provided with a plurality of conductors distributed over the circumference.

Another example of the prior art is shown in WO 2007/146252.

The object of the present invention is to provide a winding scheme which is simple and quick to produce and enables operation of the electric machine with high performance and low losses. Another object is to keep the required space, especially in the axial direction, as small as possible.

The object is achieved by a wave winding and an electric machine according to the independent claims.

According to the invention, a wave winding for an electric machine with at least one phase and a number of holes of at least two, wherein the wave winding has a standard winding step WS of WS = q * m, where q corresponds to the number of holes and m the number of phases, where at least two coil strands are provided connected in parallel at each phase, the coil strands each having a connection pin at both ends and each comprising a plurality of series strands, each strands extending once around a circumference of the wave winding, each substream being defined by a plurality of hairpins is formed, wherein each hairpin two circumferentially adjacent conductor elements, which are each connected by a turning area comprises, each hairpin having at its ends contact areas, which are each designed as a contact pin for connection to an adjacent hairpin or pin, thereby marked t, that at least three different variants of hairpins are provided, that in a first variant of the hairpins the turning area between the conductor elements has the standard winding step WS, that in a second variant of the hairpins of the turning area a second winding step, which is greater by an integer value x than the standard winding step WS, that in a third variant of the hairpin the turning area a third wrapping step, which is smaller by an integral value x than the standard wrapping step WS, and that in all three variants, the contact regions are respectively deformed by half the standard wrapping step WS in the reverse direction reversal direction, between interconnected conductor elements of adjacent hairpins to achieve the standard winding step WS.

The invention thus comprises a wave winding, which represents a distributed winding in which the coils of the winding are respectively distributed over the circumference of the electric machine. The electric machine has at least one phase, wherein also several phases, in particular three phases, can be provided.

There are provided a fixed number of magnetic poles, which are distributed over a circumference of the electric machine, this number corresponds to the number of poles and is even, since there is an equal number of magnetic north and south poles. Either the rotor, stator or rotor and stator of the electric machine have grooves for receiving the wave winding. Per phase at least two coil strands are provided connected in parallel. Preferably, the electric machine has a number of holes of at least two, which means that one pole of the number of holes corresponding number is provided in the circumferential direction of adjacent grooves. The coil strands each have a connection pin at their two ends and are in each case divided into several subsections connected in series. Each sub-string has one of the number of poles of the electrical machine corresponding plurality of conductor elements and thus extends once around the circumference. Two neighboring conductor elements are connected to each other by a turning region to a hairpin. The conductor elements are received in layers in the grooves and two adjacent layers in the radial direction form a double layer, wherein preferably the conductor elements of a sub-strand are arranged in a double layer.

Each hairpin has contact areas at its free ends. The turning region is preferably formed in one piece with the conductor elements. In order to connect neighboring hairpins, the contact area is designed as a contact pin. leads, which is connected to the electrically conductive connection, for example welding with a corresponding contact pin of an adjacent hairpin of the coil strand. The contact region can also be designed as a connection pin, which is designed to connect the coil strand, more precisely the two ends of a coil strand, to a power electronics system for controlling the electrical machine. Advantageously, contact pins and connection pins have the same geometric shape, which reduces the number of different parts, which reduces the costs and the assembly effort, whereby different geometries are possible, for example, to facilitate the connection to the power electronics.

Wave winding according to the invention have at least three different variants of hairpins in order to reduce or avoid losses due to mutual induction of the coil strands. For this purpose, in a first variant of the hairpins, the turning region between the conductor elements has the standard winding step WS, whereby the winding step and thus the distance between the grooves of the conductor elements can be achieved to the theoretical value for the number of holes and number of phases per pole always the same groove position, for example, right or left with a number of holes of two, is occupied. Hairpins in the second and third variants are therefore likewise provided in order to achieve a change between the grooves, with hairpins of the second variant having a second winding step which is greater by an integer value x than the standard winding step, and accordingly hairpins of the third variant a third winding step, which is smaller by an integer value x than the standard winding step. By these hairpins deviating from the standard winding step winding steps, the groove position of successive conductor elements can be changed, for example, with a number of holes of two from the right to the left groove or vice versa.

Common to all three variants is that the contact regions are each deformed by half the standard winding step WS in the reversing region of the opposite direction in order to achieve the standard winding step WS between interconnected conductor elements of adjacent hairpins. In other words, wave windings according to the invention on the axial side of the contact areas for all layers have a uniform winding step, whereby the production and the Connection, for example by welding Shen, the corresponding contact areas is simplified with each other. The deformation takes place per layer alternately in the opposite circumferential direction, since the conductor elements of each hairpin are arranged in different positions of a double layer.

Embodiments of a wave winding are characterized in that the integer value x satisfies the condition 0 <x <q. For a number of holes of two, this results in the value x = 1, whereby corresponding to a groove from the standard winding step deviating second and third winding steps arise to switch between the right and left groove of a pole. For higher numbers of holes can assume different values, depending on whether, for example, with a hole number of three each between the outer ßeren grooves or externa ßeren and the middle groove to be changed.

Particularly with high numbers of holes, embodiments are also possible in which further, such as fourth and fifth, variants of hairpins are provided whose deviation from the standard winding step amounts to a further value satisfying the above condition.

Wave winding according to embodiments of the invention are characterized in that at least one hairpin of the second variant and at least one hairpin third variant are provided per partial strand. By such a configuration corresponding change between the grooves is achieved.

Embodiments of the inventive wave winding are characterized in that an equal number of hairpins of the second variant and third variant are provided per partial strand. This ensures that the contact regions for the connection to adjacent partial strands or connections are each formed radially aligned at a position on the circumference, whereby the production, in particular a welding of the corresponding contact regions with each other, is simplified. Inventive embodiments of a wave winding are characterized in that at least one hairpin of the first variant is provided per partial strand. Hairpins of the first variant are preferably arranged alternately with hairpins of the second variant or third variant in order to achieve a symmetrical structure. Here, the hairpins of the second variant and third variant alternate in the circumferential direction.

Embodiments of further inventive wave windings are characterized in that four parallel coil strands are provided. Per pole and double layer, due to the number of holes of two, there are four conductor elements of different sub-strands. In addition to an embodiment with two coil strands connected in parallel, embodiments with four coil strands connected in parallel are therefore also possible. The various coil strands may each extend over all double layers or only over a part of the double layers.

Preferred embodiments of a wave winding are characterized in that in each case two coil strands are wound in the circumferential direction of opposite direction. In the case of four coil strands connected in parallel, which in each case have one partial strands per double layer, the winding for each two coil strands preferably extends in an opposite direction. This achieves a high degree of symmetry.

Embodiments of a wave winding according to the invention are characterized in that a part of each coil strand, which comprises at least one sub-strand, is wound in the circumferential direction of opposite direction. By reversing the direction of the winding, the losses are further reduced, since a higher symmetry of the wave winding is achieved. Preferred embodiments of a wave winding according to the invention are characterized in that the connection between the parts of the coil strand with different directions of the winding is formed by bridge elements, which are electrically conductively connected to the contact areas of the hairpins. Through the use of bridge elements, the uniform deformation of the contact areas of the hairpins can be maintained, which simplifies the manufacture and at the same time achieves an electrically conductive connection between the corresponding partial strands. The bridge element can easily be used to create a connection over a required circumferential area. Another advantage is that depending on the space available for the electrical machine, the bridge element is arranged either with axial or particularly preferably with a radial orientation.

Embodiments of a wave winding are characterized in that the change of the direction of the winding between the partial strands takes place in a radially outer layer. In order to minimize the number of changes between the different directions of the winding, in particular in embodiments with several double layers, whereby a more uniform structure of the hair pins is formed at the axial end of the electric machine, the changes in the radially outer layers are provided , The radially outer layer can represent both edges of the annular Hairpinwicklung in the sense of the application, so both the innermost position and the outermost layer. By a more uniform structure and the required axial space can be reduced and possibly additional components for the change can be saved. Next, the connection of the contact ends is also simplified, since it is easier to produce at the same time.

Wave windings according to embodiments of the invention are characterized in that only once the direction of the winding is changed per coil strand. In order to further uniform the structure of the wave winding at the axial ends in order to save axial space and to simplify the manufacture of the wave winding, the change between the directions of the winding only takes place once per coil strand instead. Thus, a coil strand from the connection pin first passes through the grooves of possibly several double layers to a radially outer layer and changes there the direction of the winding to then run back in the reverse direction of the winding through the grooves back to the second terminal pin of the coil strand.

Embodiments of a wave winding are characterized in that per pole in the circumferential direction adjacent conductor elements of different sub-strands of a coil strand are arranged in radially adjacent layers. Thus, viewed in the radial direction as well as in the circumferential direction, conductor elements of the different coil strands are alternately directly adjacent to one another at each pole.

By such embodiments, the degree of symmetry of the wave winding is further improved and thus space and losses can be reduced.

Embodiments of a wave winding are characterized in that the connection pins of the two coil strands are arranged in the same pole. With such a design of the required angular range for the connections to the power electronics is reduced, which can be saved according to space in the circumferential direction accordingly.

Further embodiments of the wave winding are characterized in that the connection pins of the two coil strands are arranged in the same radially outer layer. This space can be saved in the axial direction, since the connections can be made in the radial direction. For example, the connection pins can be radially outwardly formed in the radially outermost position or radially inwardly in the radially innermost position, which is why a connection to the power electronics can take place in the radial direction.

In advantageous embodiments, the connection pins are arranged both in an outer layer and in the same pole. With such embodiments, the space required for connection to the power electronics can be minimized both in the axial direction and in the circumferential direction of the electrical machine. Further objects of the invention are a stator for an electrical machine, which is characterized in that the stator is provided with a wave winding according to the preceding description and an electric machine, in which a wave winding is provided as described above.

The features of the embodiments can be combined as desired.

In the following the invention will be explained in more detail with reference to figures. The same or similar elements are designated by the same reference numerals. The figures show in detail:

Fig. 1 illustrates an embodiment of a stator with a wave winding in a side view.

Fig. 2 shows a portion of the wave winding in the region of the connection pins.

FIG. 3 (A, B, C, D) shows a winding diagram for a coil strand according to FIG. 1. FIG. Fig. 4 (A, B, C, D) shows a winding scheme for another coil strand according to

Fig. 1.

In order to ensure better representability, FIG. 3 was divided into four parts, corresponding to FIGS. 3A, 3B, 3C and 3D, FIG. 3A the upper left area, FIG. 3B the upper right area, FIG. 3C shows the lower left area and FIG. 3D shows the lower right area of FIG. 3. In the further description, these four parts will be described together and uniformly designated with FIG. For Fig. 4, which was also divided according to the aforementioned pattern, this applies analogously. Fig. 1 shows an embodiment of a stator (1) with a wave winding. The stator (1) has a stator body (2), in which grooves (3) are formed for receiving the shaft winding. In the grooves (3) conductor elements are introduced in the example shown in the form of hairpins (6, 6 ', 6 "), wherein per groove (3) a plurality of conductor elements are introduced in layers.

The hairpins (6, 6 ', 6 ") of the illustrated example each comprise two conductor elements, a turning region W, in which the conductor elements are integrally connected to one another, and contact regions K at the ends of the hairpin (6, 6', 6"). ). The hairpins (6, 6 ', 6 ") are, apart from the respective first and last hairpin (6, 6', 6") of the individual coil strands in their contact areas K with two contact pins (4) executed, each with the in Spulentrang adjacent hairpin (6, 6 ', 6 "), more precisely its corresponding contact pin (4) are electrically connected. The respective first and last hairpin (6, 6 ', 6 ") of a coil strand has a contact pin (4) for connection to the adjacent hairpin (6, 6', 6") of the coil strand and a connection pin (5, 5 ') Connection to a power electronics, not shown.

In order to enable mutual contact, all contact pins (4) of the wave winding are arranged on the same axial side of the stator (1), whereby correspondingly the turning regions W of the hairpins (6, 6 ', 6 ") on the opposite axial side of the stator (1) are arranged.

The connecting pins (5, 5 ') of the individual coil strands are provided in the example shown in each case in the radially outer layer of the wave winding and the connection pins (5, 5') of the two parallel coil strands per phase are each arranged in the same pole, whereby they Form connection areas A. Due to the arrangement in the radially outer position, a connection to the power electronics can take place in the radial direction, as a result of which no or only minimal installation space in the axial direction is required. As a result of the arrangement in the same pole, the connection pins (5) for the cathode and the connection pins (5 ') for the anode are each arranged directly adjacent in pairs. The paired connection pins (5) of the parallel coil strands for the cathode and the connection pins (5 ') for the anode are offset one pole in the circumferential direction. Through this training, we Closing a phase to the power electronics requires only a small area of the circumference, which corresponds to a winding step.

If the connection pins (5, 5 ') of the respective phases in adjacent slots are provided in several phases, as in the illustrated example three phases, the areas of the circumference required for connection to the power electronics overlap and the correspondingly required installation space can be minimized become.

On the side of the turning areas W, in regions with radially adjacent hairpins (6) of the first variant, a uniform pattern with parallel turning areas W develops due to the uniform standard winding step. In the region of the circumference, on which hairpins (6 ') of the second variant and hairpins (6 ") of the third variant are arranged adjacent in the radial direction, in order to change between a right and a left groove of the corresponding poles, forms Overlap area O off. In the overlapping area O, the turning areas W of two hairpins (6 ', 6 ") lie largely one above the other.

FIG. 2 shows a partial region of the contact regions K with the connection pins (5, 5 ') of the stator (1) according to FIG. 1. In addition, at the radially inner layer, the partial strands of the individual coil strands are electrically conductively connected by means of bridge elements (7, 7 ', 7 "), which are not shown in FIG. 1. In the further layers, the contact pins (4) of adjacent hairpins (6, 6 ', 6 "), which are connected to one another in an electrically conductive manner, are positioned adjacent to each other by the forming by half a winding step. By the bridge elements (7, 7 ', 7 ") are due to the reversal of the winding direction and the retention of the deformation by half a winding step against the direction of the turning of the Hairpin (6, 6', 6"), in the circumferential direction spaced contact pins (4) of the two sub-strands of a coil strand connected together. In the illustrated embodiment, the same length bridge elements (7) are used with a standard winding step corresponding length, through which each of the right and left grooves of the respective poles are connected.

In the example shown, the bridge elements (7, 7 ', 7 ") are provided on the radially inner layer. As an alternative, these bridge elements (7, 7 ', 7 ") can naturally also be provided on the radially outer layer and the connection pins (5, 5') on the radially inner layer. Alternatively, in the respective variants, a further change between the respectively right and left groove of the respective poles can be additionally effected by the use of different bridge elements (7 ', 7 "), whereby in each case one bridge element (7') with one the second Winding step corresponding length and a bridge element (7 ") are used with a length corresponding to the third winding step, be provided. However, a corresponding additional change is only meaningful for reasons of symmetry if the partial strands of the different double layers are provided differently, in particular with an unequal number of hairpins of the second and third variants.

Fig. 3 shows a winding scheme for a first coil strand for a phase analogous to an example shown in Fig. 1, wherein an embodiment with only 48 Nuten (3) is shown. Furthermore, contrary to FIG. 2, bridge elements (7) having a same length corresponding to the standard winding step are provided on the radially inner layer.

In the upper area (FIGS. 3A and 3B), a development of the grooves (3) is shown with a representation of the six layers here, and thus three double layers, per groove (3). In the layers, the conductor elements for a phase in the two grooves (3) per pole are numbered such that the number in each case a letter for the substring and a number for a continuous numbering of the hairpins (6, 6 ', 6 ") in Current flow direction, wherein the parallel coil strands are differentiated by capital letters or lower case letters. The conductor elements adjacent to the connection pins (5, 5 ') or, in other words, the corresponding first and last conductor elements of the coil strands are marked with arrows, the solid line arrow representing the first coil strand shown in FIG. 3 and the parallel second coil strand the phase marked with dashed lines arrow is marked.

In the lower part (FIGS. 3C and 3D), the individual partial strands for the first coil strand with the corresponding interconnection are shown. The sub-strands are each divided into blocks in the double layers corresponding blocks and the individual sub-strands per double layer are shown in separate lines. The sub-strands in the rows are shown as wavy lines which correspond to the hairpins (6, 6 ', 6 "), the upper wave portions being the contact areas K and the lower ones Shaft sections correspond to the turning portions W, and these two shaft sections each perform the winding step. The conductor elements are represented by the vertical sections of the wave-shaped line, wherein the positioning of the conductor element in the first or second layer of the double layer is indicated by differently inclined markings. The connection pins (5, 5 ') and contact pins (4) of the hairpins (6, 6', 6 ") are shown in the upper section of the wave-shaped lines, with directly adjacent contact pins (4) within a sub-strand electrically conductive, for example by welding, are connected.

Interconnected contact pins (4) of different partial strands are connected by corresponding arrows. The arrows between the individual double layers in this case represent a direct connection, for example by welding, the contact pins (4) of the corresponding hairpins (6, 6 ', 6 "). The bridge element (7) is shown by the arrow within the last double layer. by which the partial strands are electrically connected to each other.

In the illustrated example, a change from a left-hand groove (3) to a right-hand groove (3) takes place through the turning regions W, distributed over the circumference, by providing a hairpin (6 ') of the second variant. In the further course of the sub-strand, a hairpin (6 ") of the third variant is provided to change again from a right into a left-hand groove (3). In the illustrated example, hairpins (6) of the first variant are provided between the hairpins (6 ', 6 ") of the second and third variants. This achieves a high degree of symmetry, which reduces the losses. Depending on the number of poles and the like, a different distribution of the hairpins (6, 6 ', 6 ") of different variants over the circumference is possible, such as directly adjacent hairpins (6', 6") of the second and third variants. te with attached hairpins (6) of the first variant. In general, a largely symmetrical structure is preferred. In the course of a coil strand, the hairpins (6, 6 ', 6 ") are arranged with the same variant per winding direction in each case at the same position on the circumference, whereby a uniform structure of the winding head is achieved.

The first coil strand, as shown in FIG. 3, first passes through the radially outer double layer with the first partial strand. The first substring goes through a ing connection of the contact pins (4) in the second sub-strand, which runs in the same direction of the winding analogous to the first sub-strand through the next Dop- pellage. In this way, first the grooves (3) of the double layers are traversed with a same direction of the winding from radially outside to radially inside. At the last contact pin (4) of, here third, sub-string in the radially inner layer is made by a bridge elements (7), the electrically conductive connection with the first contact pin (4) of the fourth sub-strand here.

In this connection via the bridge element, a reversal of the direction of the winding takes place. In the example shown, a winding step corresponding to the standard winding step from here 6 is performed by the bridge element (7). Alternatively, as in the embodiment shown in FIG. 2, bridge elements (7, 7 ') with different winding steps corresponding to the second or third winding step are also possible in order to change from a left-hand groove into a right-hand groove.

The fourth sub-strand, which passes through the grooves in the radially inner double layer in the opposite direction, then passes into the fifth sub-strand, which also passes through the grooves in the adjacent double layer. The partial strands returning to the radially outer layer have an analogous structure to the abovementioned partial strands. The last hairpin of the sixth sub-string here has at its end, which also shows the end of the first coil strand, corresponding to the connection pin (5) for connection to the power electronics.

4 shows a winding scheme for a second coil strand for one phase according to the example shown in FIG. 1, which is connected in parallel with the first coil strand, analogous to that shown in FIG. 3. Fig. 4 shows an embodiment with 72 distributed over the circumference grooves (3), wherein not all grooves are shown. The illustration is constructed analogously to FIG. 2, wherein the second coil strand initially, starting from the connection pin (5 '), passes through the grooves (3) of the double layers to the radially inner double layer. The direction of the winding corresponds to the direction of the winding of the first coil strand. In the radially inner double layer of the change of the direction of the winding also takes place by a bridge element (7) on the side of the contact areas K. Subsequently, the sub-strands of the second coil strand through the grooves of the double layers to the radially outer ßeren double layer and ends in the connection pin (5). In contrast to the first coil strand, in the second coil strand shown here, a change from a right-hand groove (3) to a left-hand groove (4) first takes place by means of a hairpin (6 ") of the third variant. Again, a regular structure, that is, a regular arrangement of hairpins (6, 6 ', 6 ") of different variants, preferably, in particular a largely symmetrical structure.

By a construction shown in the figures, a very high degree of symmetry in the coil of the stator (1) is achieved, whereby losses due to mutual induction of the coil strands can be minimized.

However, the invention is not limited to this embodiment. As stated above, only individual advantageous features can be provided. Also, embodiments with a different number of double layers and the like are possible.

Bezuaszeichen

1 stator with winding

2 stator body

3 groove

4 contact pin

5, 5 'connection pin

6, 6 ', 6 "hairpin

7, 7 ', 7 "bridge elements

K contact area

W turning range

O overlap area

A connection area per phase and pole

Claims

claims

1 . Wave winding for an electrical machine with at least one phase and a number of holes of at least two,

wherein the wave winding has a standard winding step WS of WS = q * m, where q corresponds to the number of holes and m to the number of phases,

wherein at least two coil strands are provided connected in parallel per phase,

wherein the coil strands each have a connection pin (5, 5 ') at their two ends and in each case comprise a plurality of partial strands connected in series, each substrand extending once around a circumference of the wave winding,

each sub-strand being formed by a plurality of hairpins (6, 6 ', 6 "), each hairpin (6, 6', 6") comprising two circumferentially adjacent conductor elements, each connected by a turnaround W wherein each hairpin (6, 6 ', 6 ") has contact areas K at its ends, which in each case are in the form of a contact pin (4) for connection to an adjacent hairpin (6, 6', 6") or as connection pin (5, 5 ') are executed,

characterized in that at least three different variants of hairpins (6, 6 ', 6 ") are provided,

that in a first variant of the hairpins (6) the turning region W between the conductor elements has the standard winding step WS,

in a second variant of the hairpins (6 '), the turning region W has a second winding step, which is greater by an integer value x than the standard winding step WS,

in a third variant of the hairpins (6 "), the turning region W has a third winding step, which is smaller by an integer value x than the standard winding step WS

and that in all three variants of the hairpins (6, 6 ', 6 "), the contact regions K are respectively deformed by half the standard winding step WS in the opposite direction to the reversal region W, in order to separate between interconnected conductor elements of neighboring hairpins (6, 6) ', 6 ") to reach the standard winding step WS.

2. wave winding according to claim 1, characterized in that the integer value x satisfies the condition 0 <x <q.

3. wave winding according to one of the preceding claims, characterized in that per sub-strand at least one hairpin (6 ') of the second variant and at least one Hairpin (6 ") third variant are provided.

4. wave winding according to one of the preceding claims, characterized in that per sub-strand an equal number of hairpins (6 ', 6 ") of the second variant and third variant are provided.

5. Wave winding according to one of the preceding claims, characterized in that per sub-strand at least one hairpin (6) of the first variant is provided.

6. Wave winding according to one of the preceding claims, characterized in that four parallel coil strands are provided.

7. wave winding according to claim 6, characterized in that in each case two coil strands are wound in the circumferential direction of opposite direction.

8. Wave winding according to one of claims 1 to 6, characterized in that a part of each coil strand, which comprises at least one sub-strand, is wound in the circumferential direction of opposite direction.

9. wave winding according to claim 8, characterized in that the change of the direction of the winding between the sub-strands takes place in a radially outer layer.

10. wave winding according to claim 8 or 9, characterized in that the connection between the parts of the coil strand with different direction of the winding by bridge elements (7, 7 ', 7 ") is formed, which with the contact areas K of the hairpins (6, 6 ', 6 ") are electrically connected.

11. Wave winding according to one of the preceding claims, characterized in that the connection pins (5, 5 ') of the coil strands are arranged in the same pole.

12. Wave winding according to one of the preceding claims, characterized in that the connection pins (5, 5 ') of the two coil strands are arranged in the same radially outer layer.

13. stator (1) for an electrical machine, characterized in that the stator (1) is provided with a wave winding according to one of claims 1 to 12.

14. A rotor for an electric machine, characterized in that the rotor is provided with a wave winding according to one of claims 1 to 12.

15. Electrical machine, characterized in that at least one shaft winding according to one of claims 1 to 12 is provided.