Stator having hollow conductors, and method for producing same

Abstract

The invention relates to a stator comprising: - at least one coil unit having a plurality of conductors (20a-20f) of which at least one conductor is in the form of a hollow conductor, and - a stator core (30) comprising at least one receiving region (31), such as a slot. At least some of the conductors are electrically interconnected in series. One or more conductors are received in the receiving region (31). The conductors differ from one another at least in part, for example in terms of cross-section, shape, outer dimensions, or diameter of the cavity or channel.

Description

[0001] STATOR WITH WAVEGUIDES AND ITS MANUFACTURING METHOD

[0002] Technical area

[0003] The invention relates to a stator for an electrical machine and to a method for producing such a stator. Furthermore, the invention relates to an electrical machine having such a stator.

[0004] State of the art

[0005] The design of electrical machines with waveguide windings already allows a significant increase in current density through the principle of direct winding cooling. However, the integration of the cooling function into the current-carrying waveguide creates an optimization conflict between the optimal design of the electrical machine, particularly the winding from an electromagnetic perspective, and the optimal design of the hollow channel and thus of the conductor from a fluidic or hydraulic perspective on the cooling system side.

[0006] From a fluid dynamics perspective, it is often preferable to use large hollow channels and therefore comparatively solid waveguides so that the pressure drop to be covered by a coolant pump when pumping the coolant through the waveguide winding is as small as possible. The aim is to use a coolant pump that is as compact and cost-effective as possible. From the point of view of optimal electromagnetic dimensioning, it is advantageous to use conductors that are as thin or flat as possible for power-dense drives with a high pole change frequency. This design suppresses additional losses in the winding generated by the current displacement effect. These additional losses are added to the ohmic losses in the current-carrying conductor and lead to an undesirable reduction in efficiency and to additional heating of the stator.

[0007] In industrially mass-produced electrical machines, a waveguide wire is continuously processed from a reel and wound into a coil. This ensures that the conductor's type and dimensions—i.e., its shape and size—are fixed and identical for every position of the conductor in the stator slot. The optimization conflict described above and the associated disadvantages in the conductor design are defined by the choice of a specific wire.

[0008] In the field of large engines with over 1 ,000 kW output, such as turbo generators, waveguide cooling is state of the art. Here it is common practice to process not just a single wire, but a bundle of hydraulically and electrically connected waveguide wires in parallel to form a coil. Wound coils are used, and with each turn of the coil, a fixed and identical cross-section through the conductor bundle is repeated in the successive positions (alternatively called "layers") within a stator slot. The optimization conflict described and the associated disadvantages are also defined here by the choice of wire or wires within the recurring bundle.

[0009] Additive manufacturing technology theoretically allows for the printing of highly imaginatively shaped conductor geometries optimized for their position within a specific slot as a complete winding. However, this technology is significantly more energy-intensive and therefore more expensive than the conventional continuous drawing and coating of wire from a coil, and thus does not represent an alternative for series production optimized for low cost and high speed.

[0010] For example, the document DE 10 2021 119 405 A1 is known, which relates to a stator for an electrical machine, which has a stator core with at least one stator slot in which at least two electrical conductors are arranged. At least part of the stator is produced by means of an additive manufacturing method, wherein, for a predetermined number of electrical conductors, at least one cooling channel is designed which can be supplied with a cooling fluid, wherein at least one first and one further cooling channel group, in which the cooling channels of a plurality of electrical conductors can be supplied with cooling fluid parallel to one another, are fluidically connected to form separate circuits or to form one circuit in series and / or in parallel.

[0011] In the field of electrical waveguide machines, the document DE 10 2020 201 748 A1 is also known, which relates to an electrical machine with a stator which has slots for receiving an electrical plug-in winding, wherein the electrical plug-in winding is a distributed multi-phase winding and is formed from electrical conductor elements located in the slots. A large number of the conductor elements of the plug-in winding are designed as waveguides. A coolant distributor is provided on one of the two winding heads, which is electrically insulated from the hollow conductor elements, has an inlet for supplying an electrically non-conductive coolant, in particular oil, from a coolant supply, and from which the coolant can be conducted into a plurality of the hollow conductor elements.

[0012] What the described publications have in common is that there is a fixed shape or arrangement of the conductor(s) along the electrical path of a coil and / or along a stator slot.

[0013] Subject of the invention

[0014] An object of the invention is to provide a stator which leads to a higher efficiency in an electrical machine and enables a compact, material-saving and cost-effective design.

[0015] The stator according to claim 1 provides a solution for this. Further preferred embodiments are explained in the dependent claims and in the following description.

[0016] According to the invention, a stator is provided, comprising: at least one coil unit with a plurality of conductors, comprising at least one waveguide, wherein at least some conductors are electrically connected to one another in series, and a stator core having at least one receiving region, preferably a plurality of receiving regions (in particular three or more receiving regions), wherein one or more conductors are received in the receiving region. The conductors differ from one another at least in part.

[0017] Since the conductors of a coil unit differ at least partially, one conductor may be designed differently than the others (which may, for example, be identical). However, several conductors may also differ from one another.

[0018] In particular, the conductors, preferably of a coil unit, are electrically connected in series. In particular, the conductors differ in their shape and / or configuration when viewed in cross-section. This allows for the provision of a stator with high efficiency and optimized design.

[0019] The stator according to the invention provides in particular a structure in which a shape and arrangement of conductors is optimized according to the position within the receiving area.

[0020] In particular, the conductors can be varied in such a way that an external shape, in particular a width and / or height, a design as a waveguide or solid conductor, a design as a single conductor or conductor bundle, and / or a shape and / or a diameter of a channel (in the case of a waveguide) are varied.

[0021] It is also possible to use a solid conductor without a channel that is not designed as a waveguide, or an arrangement of several waveguides connected electrically in parallel within this section of the winding, or a plurality of solid conductors, or a mixture of both.

[0022] The individual conductors, which differ at least partially from one another (for example waveguides, solid conductors and / or bundles of waveguides and / or solid conductors, or as a mixture thereof), form sections of a serial current path.

[0023] The individual conductors, which differ at least partially from one another, form as a whole a coil unit with two electrical connections.

[0024] These conductors, as components of a coil unit, are also referred to below as pins. Pins can be distinguished in that pins that run through a single receiving area, in particular a single slot, with a start and an end of such pins each terminating in an opposite winding head of the stator, are referred to as "I-pins," while pins that run through two receiving areas, in particular slots, of a stator and have a start and end in the same winding head are referred to as "hairpins."

[0025] "Pins" and "conductors" are used below as synonymous terms, whereby an arrangement of the pins / conductors connected electrically in series as described forms a coil unit, whereby the pins / conductors can be designed as waveguides or solid conductors or as a bundle of waveguides or solid conductors or as a mixed form of the like.

[0026] One or more identical coil units can be electrically interconnected in any way, either in series or in parallel, or as a combination of series and parallel connections, like conventional coils. The interconnected coil units collectively form phases or strands of a multiphase electrical machine.

[0027] The position of the interconnection or connection points of the individual conductors of a coil unit outside the slot of the stator is usually referred to as the "winding head", even if in this case the winding is not continued continuously with the same wire, but the conductors are electrically contacted with one another as sections of a coil unit in the winding head.

[0028] Within a coil unit, there is at least one waveguide or a bundle of electrically (and hydraulically) parallel waveguides. The individual waveguides each have an inlet and outlet for the coolant at their respective ends, which preferably open into a hydraulic collector in the winding head for the inflow and outflow of the coolant.

[0029] It is preferred that a collector is provided at each opposite end of the stator core, and that the conductors are hydraulically connected in parallel. According to another embodiment, a collector for a coolant inlet and outlet is arranged on the same side of the stator core.

[0030] In an advantageous embodiment, the hydraulic collector is made of an electrically insulating material and extends at least partially over the area of ​​the winding head and in particular the area of ​​the contact points of the pins in order to insulate the end pieces of the pins, which may be located close to one another and stripped for the purpose of electrical contact in this area, from one another.

[0031] In a particularly advantageous embodiment, all the conductors installed in the stator are waveguide I-pins, and if present in this way, including all the waveguide I-pins which are already hydraulically and electrically connected in parallel as individual elements of a waveguide bundle, are hydraulically connected in parallel to one another, with the channels of the waveguides each opening into a ring-shaped hydraulic collector on both sides of the stator, with a cooling liquid flowing through the waveguides in the same axial direction of the stator.

[0032] In a further particularly advantageous embodiment, the conductors are designed as waveguide hairpins and arranged such that all ends open into annular collectors on one side of the stator, with or after the winding head, wherein at least one annular collector is provided for the inlet and at least one annular collector is provided for the outlet of the cooling liquid. These advantageous designs can be applied analogously to axial flux machines with an inner and outer annular collector, as well as to transverse flux machines and to electrical machines with one or a plurality of stators and thus each with a plurality of both inlet collectors and outlet collectors.

[0033] The arrangement according to the invention provides for a particularly advantageous arrangement in which a particularly thin and / or flat design of the waveguides or solid conductors or finely segmented bundles of conductors / pins (in particular a bundle of flat wires) is used in the "outer" layers, which are located at the air gap between the stator and rotor, because this design very effectively suppresses the so-called AC winding losses, which are generated in particular in the outer layers by the current displacement effect.

[0034] In the "lower" layers in the slot base, where the term "slot base" refers to the closed lower side of the slot at the stator yoke, if present, the waveguides can, for example, be solid, so that a comparatively high fill factor can be achieved with the conductor material, in particular copper or aluminum. The current displacement effect is less significant in this area. Thus, in every position / layer of the slot, an optimal compromise can be found between suppressing current displacement losses using thin and / or segmented conductors (conductor bundles) and reducing the ohmic DC winding losses using a high fill factor with solid and / or unsegmented conductors.

[0035] Primarily, the shape or cross-section is described by the conductors or conductor bundles within the stator slots or along the active length of the stator core. This shape or cross-section can continue at least partially in the area of ​​the winding overhang, whereby a slight change in shape can occur in one or both end sections of a conductor for the purpose of better contact or as a result of the stripping process. The fact that the conductors are surrounded by an electrically insulating layer, except in the area where their end sections are contacted, in order to insulate them from one another is self-evident to a person skilled in the art and is not specifically highlighted in the figures or the further description.

[0036] Likewise, in the field of electrical machines it goes without saying that the stator is made of a soft magnetic material, usually in the form of a stack of electrical sheets, although SMC or printed soft magnetic elements can also be used.

[0037] Not further described or shown in the figures, but equally obvious, is that a further layer of insulation material is usually provided, wrapped around the conductors or inserted in the grooves.

[0038] Furthermore, the receiving area of ​​the winding in the stator package can be designed as a slot, wherein the slots of a stator are usually designed as parallel slots, since they are adapted to the fixed width of a conductor.

[0039] A stator according to the invention makes it possible to design receiving areas or slots with trapezoidal flanks or in a stepped manner so that a maximum fill factor can be achieved with the conductor material, e.g. copper or aluminum. In an advantageous embodiment, for the example of a radial flux internal rotor machine, the conductors in the slot base are wider than those which are closer to the air gap. A further advantage of the stepped design of a slot is the better fixing of the pins / conductors in the slot when the stator is fitted, as well as the better thermal connection between the stator package and the pins / conductors.

[0040] It is also advantageous for one or more of the conductors to be designed as solid conductors or waveguide bundles. This particularly applies to the section(s) of the coil unit that are arranged closer to an air gap in the stator.

[0041] The end sections of the conductors are electrically contacted or joined to one another as described. In an advantageous embodiment, the (stripped) end sections can be connected, in particular in pairs, to a sleeve, preferably enclosed by a sleeve, wherein, in a further advantageous embodiment, the sleeve does not influence the hydraulic flow of a coolant through the waveguide channel. Said sleeve can encompass the end sections. The sleeve can have an opening region, or according to another embodiment, the sleeve is designed to be closed.

[0042] It is preferred that the sleeve , in addition to joining the conductors to one another , effects an electrical coupling of the end sections of the conductors and is also made of an electrically ( highly ) conductive material such as copper .

[0043] Furthermore, the sleeve can be provided with features, e.g., webs or tabs, for clamping or pressing around the end sections of the conductors. Furthermore, it is preferred to fill the contact area between the sleeve and the conductor end sections with solder in order to achieve ideal electrical contact. Other joining methods, such as, e.g., welding or pressing, are also possible.

[0044] Furthermore, it can be provided that the conductors have a rectangular cross-section. The respective end sections of the waveguides open into one or a plurality of hydraulic collectors. A collector can be formed from an electrically insulating potting compound that extends at least partially around the end sections of the individual conductors.

[0045] The collector can have one or a plurality of elevations, which in an advantageous embodiment are designed as a circumferential web or circumferential webs, in particular between those end sections which are not contacted with one another in pairs via end sections of the conductors or sleeves and thus have a voltage difference between them during operation. By means of this elevation(s) or web(s), the air and creepage distance between those conductors which have a voltage difference between them during operation can be increased. This makes it possible to provide a winding with a higher number of layers in the slot or to design an electrical machine for a higher voltage class, which opens up greater design freedom when designing an electrical machine and consequently means a better optimized machine with a higher level of efficiency.

[0046] According to a preferred embodiment, the conductors form a coil unit, wherein the coil unit has a helical or meandering course. A coil unit is formed by a plurality of conductors electrically connected in series.

[0047] According to a further aspect of the invention, an electrical machine is provided, comprising a stator according to one of the preceding embodiments. With regard to the advantages of this electrical machine, reference is made to the explanations of the stator described above. In a further embodiment, the electrical machine can have a stator and two rotors, in particular a double rotor with mechanical coupling of the two rotors, in the case of a radial flux machine an outer and an inner rotor. One advantage of such an arrangement is the omission of the stator yoke. The individual stator teeth can be connected to one another via thin webs or a plurality of webs for the purpose of mechanical fixing. In such a double rotor arrangement, the stator has two air gaps to the two rotors. It is preferred that the conductors which lie at the respective air gap are designed as conductor orWaveguide bundles are formed, while the conductors "inside" are preferably designed as unsegmented solid waveguides or conductors. The arrangement of the conductors can be symmetrical in a further design and can be combined as desired, e.g. with the stepped design.

[0048] Hairpins are particularly advantageous for double-rotor arrangements because the mechanical coupling of the rotors prevents access to the winding head on either side of the stator. Designing such a stator with hairpins means that two adjacent layers have the same conductor type (for example, in the case of waveguides, the same cross-section of the channel), since the two end sections of a hairpin are offset from one another, i.e., run in different layers. The hydraulic contacting or the attachment of the hydraulic collectors on one side of the machine is carried out according to the position of the conductor end sections.

[0049] In an advantageous arrangement, the plurality of hydraulic accumulators is arranged concentrically in a radial flux machine and simultaneously in an axial flux machine along a rotational axis of the rotor. An electrical machine can be designed as a radial flux machine with an internal rotor design. The radial flux machine can also be designed as an external rotor design or in a design with a double rotor. The principle can be transferred to other electrical machines, including electrical machines with one or more stators or with one or more rotors, analogous to the aforementioned axial flux and transverse flux machines.

[0050] Although a distributed winding of I-pins is primarily described here, the inventive procedure can equally be used for stators with concentrated winding.

[0051] According to a further aspect of the invention, a method for producing a stator is provided, wherein the stator comprises at least one coil unit with a plurality of pins / conductors, wherein at least one conductor is designed as a waveguide. The conductors of the coil unit differ at least partially from one another. The method comprises the steps of: providing a stator package which has at least one receiving area, preferably a plurality of receiving areas (in particular three or more receiving areas), and inserting the conductors into the receiving area, wherein the conductors are electrically connected to one another in series.

[0052] In particular, the conductors can be varied in such a way that an external shape, in particular a width and / or height, a design as a waveguide or solid conductor, a design as an individual conductor or conductor bundle, and / or a shape of a channel and / or a channel diameter (in the case of a waveguide) are varied. Within a conductor bundle (alternatively referred to as a segmented conductor), all the individual conductors are connected electrically in parallel and, if waveguides are used in the bundle, also hydraulically in parallel. A segmented conductor / the conductor bundle can be made up of several waveguides or a plurality of solid conductors or a hybrid form of waveguide(s) with solid conductor(s).

[0053] The method comprises the steps of: providing a stator package which has a receiving area in the form of an open slot, inserting a plurality of conductors into the receiving area, and electrically contacting the conductors.

[0054] The extension of the method can include: providing a stator package which has a receiving area in the form of a closed or partially closed slot, inserting a plurality of conductors into the receiving area in the axial direction (for a radial flux machine), forming the straight end(s) of the conductor inserted through the stator in the area of ​​the winding head ("twisting"), electrically contacting the conductors.

[0055] Short description of the drawings

[0056] Fig. 1a illustrates an overall structure of a winding for a stator consisting of a plurality of coil units of serially connected waveguide I-pins.

[0057] Fig. 1b shows a detailed view of a coil unit according to the invention, which is composed of waveguide I-pins and a bundle of waveguides in an electrically serial arrangement, wherein the bundle of waveguides itself is electrically connected in parallel.

[0058] Fig. 1c shows a detailed view of another coil unit according to the invention according to a modification (meander-shaped arrangement). Fig. 2 shows an arrangement of waveguides according to a first embodiment, which differ in size and type.

[0059] Fig. 3 shows an arrangement of waveguides according to a second embodiment in a trapezoidal groove with a stepped flank.

[0060] Fig. 4 shows an arrangement according to a third embodiment for a stator of a double-rotor machine, wherein the conductors are designed as waveguide hairpins and waveguide bundle hairpins.

[0061] Fig. 5 shows an arrangement of waveguide sections in hairpin design according to a fourth embodiment for a stator of a double rotor machine, wherein the conductors are

[0062] Waveguide hairpins of different heights are used.

[0063] Fig. 6 shows an arrangement of conductors according to a fifth embodiment.

[0064] Fig. 7 shows an arrangement of conductors according to a sixth embodiment.

[0065] Fig. 8 shows an arrangement of conductors according to a seventh embodiment, wherein waveguide I-pins are combined with waveguide bundle I-pins and a bundle of solid flat wire.

[0066] Fig. 9 is a view of an end portion of a stator according to an embodiment of the invention. Description of Embodiments

[0067] Exemplary embodiments of the invention are described below with reference to the figures. Features of the respective embodiments can be combined to create further variants.

[0068] Fig. 1a illustrates the overall structure of a stator winding comprising a plurality of coil units, which is used for an electrical machine. The coil unit is to be understood as a combination of conductors (here: waveguide I-pins) 20 connected electrically in series, wherein the individual conductors 20 differ from one another in type and / or shape, as described below with reference to the embodiments.

[0069] Fig. 1b shows an arrangement according to the invention in which the conductors 20 are designed differently within the coil unit. In this case, the conductors 20 consist of waveguide I-pins combined with a bundle of waveguide I-pins connected electrically in parallel. The individual conductors are each located in different positions in the stator slots (in the inserted state and with the bundle lying completely in one position). This arrangement makes it possible for all conductors 20, regardless of the electrical contact, to be connected hydraulically in parallel to the respective inlet and outlet headers, which leads to very low hydraulic pressure requirements and to very effective cooling of the conductors. End sections of the conductors 20 are connected in pairs to a sleeve 15, the sleeve 15 enclosing the conductors 20 from the outside.

[0070] In Fig. 1b, a coil unit (without stator package with slots) is shown which extends radially from an air gap to a slot base like a "helix". For example here with four serial conductors 20, but there could also be 2, 4, 6, 8, etc. conductors 20. In this case, positions / layers "skipped by one" in a respective slot are occupied and occupied with half the number of conductors of an entire coil unit.

[0071] Fig. 1c shows a modification of the design shown in Fig. 1b. Instead of a "spiral," this creates a meandering pattern that moves along the "unwound" stator and occupies only one slot with a conductor. Figuratively speaking, the conductor 20x ascends upwards along the slot "like a staircase." Alternatively, the conductors 20x can also be interconnected like classic hairpins, encircling adjacent layers completely before the aforementioned staircase-like ascent to the next layers occurs. End sections of the conductors 20x are connected in pairs with a sleeve 15x. Other joining processes, such as welding, can also be used to contact the end sections.

[0072] Fig. 2 shows a single slot surrounded by stator teeth and filled with multiple conductors (here: waveguide pins) of different designs. A stator core 30 of the stator has a plurality of receiving areas (stator slots) 31. The stator shown here is intended for a radial flux machine designed as an internal rotor, whereby the principle explained is also transferable to an external rotor, as well as to axial flux motors, and motors with multiple stators or motors with multiple rotors.

[0073] According to the first embodiment shown in Fig. 2, the stator core 30 comprises stator slots 31 in the form of a partially closed slot. The partially closed slot is bordered by tooth tips that point towards one another. In this receiving area (the stator slot) 31, several types and size variations of conductors designed as waveguide I-pins are accommodated. In particular, these are a first waveguide 20a, a second waveguide 20b, a third waveguide 20c, a fourth waveguide 20d, a fifth segmented conductor as a bundle of waveguides 20e connected electrically in parallel, and a sixth segmented conductor as a bundle of even smaller waveguides 20f connected electrically in parallel.

[0074] The designs of the (hollow) conductors 20a-20f differ from one another according to the invention.

[0075] It is advantageous that the segmentation of the conductors, or rather the height of the individual conductors, increases toward an air gap between the stator and rotor. This design ensures that so-called AC winding losses, which can be generated by a current displacement effect, particularly in the layers near the air gap, are suppressed. These losses add up to the ohmic losses in a current-carrying conductor and lead to additional heating and a reduction in the efficiency of the electric motor.

[0076] The inner conductors 20a and 20b are formed by a comparatively solid waveguide (a waveguide with a comparatively pronounced wall) to provide a better fill factor within the groove. The previously described current displacement effect, which is clearly pronounced in the area of ​​the air gap, is less relevant in this deep section of the receiving area 31.

[0077] Fig. 3 shows a second embodiment of a stator which, like the first embodiment, has a stator core 30' and receiving areas formed therein (a receiving area 31' is clearly shown in Fig. 3). The stator shown in Fig. 3 is intended for a radial flux machine which is designed as an internal rotor. However, the principle shown can also be applied to an external rotor, as already explained in the context of the first embodiment.

[0078] The tooth of the stator core 30' shown from the left side in Fig. 3 has a straight surface to form the receiving area 31', wherein if designed in this way on both sides the resulting tooth has parallel flanks, whereas the slot is trapezoidal. In Fig. 3 on the right side of the stator core 30' the tooth shown has a stepped flank, whereby a tooth with stepped flanks is formed which provides approximately the same, but not identical, cross-sections for conducting the magnetic flux. The advantage of this respective configuration is uniform saturation of the soft magnetic tooth with magnetic flux and comparatively more installation space for the waveguide in the slot, which leads to a reduction in the current density in the conductor, fewer conductor losses and improved efficiency.

[0079] With regard to further aspects, reference is made to the embodiment described above.

[0080] Fig. 4 illustrates a double-rotor arrangement of a radial flux machine. This arrangement comprises a stator core 30'', which has a first receiving area 31''-1 and a second receiving area 31''-2.

[0081] According to a modification of the embodiment shown in Fig. 4, several webs are provided for structurally connecting the teeth. According to another modification, it is also possible to provide individual teeth of the stator core without a web.

[0082] In the first receiving area 31 ' '-1, which is designed as a partially closed groove, a first conductor 20a' ', a second conductor 20b' ' and a third conductor 20c' ' are provided, whereas in the second receiving area 31 ' '-2 a fourth conductor 20d' ', a fifth conductor 20e' ' and a sixth conductor 20f' ' are arranged.

[0083] Both I-pins and hairpins are possible in this design. The hairpin design is particularly advantageous for dual-rotor motors, as it allows the hydraulic accumulators to be mounted on a single face of the stator, due to the limited access provided by the dual rotor.

[0084] In this case, the "outer" conductors 20a' ' and 20f ' ' at the respective air gap are designed such that the waveguide dimensions, in particular the heights, are small compared to the "inner" conductors 20c' ' and 20d' '. The design as a hairpin variant entails that the adjacent layers 20a' ' with 20b, 20c' ' with 20d' ' and 20e' ' with 20f ' ' are identical, i.e. each have the same geometry and / or the same type, since a hairpin conductor jumps one layer as it runs through two slots through a stator core. Furthermore, a variation between an electrically parallel waveguide bundle and a single (wave) conductor is shown.

[0085] With regard to further aspects, reference is made to the embodiments described above.

[0086] The fourth embodiment shown in Fig. 5 partially corresponds to that of Fig. 4, so that additional reference is made to the explanations for the third embodiment. However, the dimensions and designs of the conductors 20a' ' ', 20b' ' ', 20c' ' ', 20d' ' ', 20e' ' ', and 20f' ' ' are designed differently than in Fig. 4. In particular, the "outer" conductors 20a' ' ', 20f' ' ' are flatter compared to the respective inner conductors 20c' ' ', 20d' ' '.

[0087] Fig. 6 shows a fifth embodiment of a stator in a double rotor arrangement. The stator comprises a stator core 30' ' ' ', which has a first receiving area 31' ' '-1 and a second receiving area 31' ' '-2. The receiving areas 31' ' '-1 and 31' ' '-2 are separated from one another by a web 32' ' ' . A first conductor 20a' ' ' ', a second conductor 20b' ' ' ' and a third conductor 20c' ' ' ' (which are designed as a waveguide hairpin bundle and a waveguide hairpin) are arranged in the first receiving area 31' ' '-1. Analogously, a fourth conductor 20d' ' ' ', a fifth conductor 20e' ' ' ' and a sixth conductor 20f ' ' ' ' (which are also each designed as a waveguide hairpin bundle and waveguide hairpin) are provided in the second receiving area 31 ' ' '-2.

[0088] The first receiving area 31' ' '-1 is provided with a step, which allows the hairpin waveguide bundle of the outer layers 20a' ' ' with 20b' ' ' to be wider and therefore with reduced current density. The advantageous reduction in current displacement losses due to flatter individual conductors compared to the inner layers has already been described.

[0089] Fig. 7 shows a double rotor arrangement with I-pin design according to a sixth embodiment. In the stator package 30' ' ' ' , a first receiving area 31' ' ' ' '-1, a second receiving area 31 ' ' ' ' '-2 and a third receiving area 31 ' ' ' ' '-3 are provided. Between the first receiving area 31 ' ' ' ' '-1 and the second receiving area

[0090] 31 ' ' ' ' '-2 is a first web 32 ' ' ' ' '-1 and between the second receiving area 31 ' ' ' ' '-2 and the third

[0091] Receiving area 31 ' ' ' '-3 has a second web 32 ' ' ' '-2 formed.

[0092] The first receiving area 31 ' ' ' '-1 accommodates a first conductor 20a' ' ' ' ', which according to this embodiment is designed as a waveguide bundle. The second receiving area 31 ' ' ' '-2 accommodates a second conductor 20b' ' ' ' ', a third conductor 20c' ' ' ' ', a fourth conductor 20d' ' ' ' ' and a fifth conductor 20e' ' ' ' '. The third receiving area 31 ' ' ' '-3 accommodates a sixth conductor 20f' ' ' ' ', which is designed as a waveguide I-pin bundle.

[0093] In this embodiment, at least one collector (not shown in Fig. 7) is provided on both end faces of the stator. The (hollow) conductors 20a ' ' ' ' '-20f ' ' ' ' are connected electrically in series and hydraulically in parallel within a coil arrangement. The coolant can flow from one end face of the stator to the other end face of the stator. In a further embodiment, a collector for diverting the coolant can be provided on one side, while at least one inlet and at least one outlet collector are mounted on the opposite side.

[0094] Fig. 8 shows a seventh embodiment of a stator which has a stator core 30' ' ' ' ' and a receiving area 31' ' ' ' ' '. In the receiving area 31' ' ' ' ' ' a first conductor 20a' ' ' ' ' ', a second conductor 20b' ' ' ' ' ', a third conductor 20c' ' ' ' ' and a fourth conductor 20d' ' ' ' ' ' are received.

[0095] The first and second conductors 20a ' ' ' ' ' - 20b ' ' ' ' ' are designed as waveguides and the third conductor 20c ' ' ' ' is designed as a waveguide bundle. The fourth conductor 20d ' ' ' ' ' in this embodiment is designed as a bundle of parallel flat wires, although instead of a flat wire it is also possible to use a bundle of formed wire or a pressed stranded wire. This is particularly advantageous in electric motors with a power-dense design and a comparatively high electrical fundamental frequency, since waveguides cannot be manufactured as small as a drawn wire and in particular stranded wire. The illustration in Fig. 9 is intended to clearly explain a design with waveguide pins with a large number of parallel channels. In comparison to known embodiments, this design enables a relatively short individual channel length, low pressure losses in the cooling circuit and more effective cooling.However, the more layers of waveguides such a stator has, the more challenging it becomes to insulate them from each other via a clearance and creepage distance. The conductors 20' can be arranged as shown in Fig. 9.

[0096] Furthermore, the embodiment shown in Fig. 9 has elevations / webs 45' in the region of a section of the collector 40', which are formed from an electrically insulating material. In Fig. 9, only a section of the collector 40' is shown, which is closed, for example, by a cover or the like. According to this exemplary embodiment, the section of the collector 40' has a circumferential groove into which a sealing ring can be inserted to seal against the cover of the collector (not shown). By increasing the air and creepage distance by means of the elevations 45' in the axial direction, a radially higher packing density, in particular an increase in the number of waveguide layers, is enabled, which leads to a better designed and more efficient electrical machine.

[0097] The configurations described in the context of the preceding embodiments can be used both in a radial flux machine and in an axial or transverse flux machine.

Claims

HE 269,000 pl Claims 1. Stator, comprising: - at least one coil unit with a plurality of conductors (20, 20'; 20a-20f - 20a ' ' ' ' ' '-20f ' ' ' ' ' ') comprising at least one waveguide, wherein at least some conductors (20, 20x; 20'; 20a-20f - 20a ' ' ' ' ' '-20f ' ' ' ' ' ' ) are electrically connected in series with one another, and - a stator package (30-30' ' ' ' ') which has at least one receiving area (31-31'; 31 ' '-1, 31 ' '-2; 31 ' '-1- 31" '-2; 31""-1, 31""-2; 31" '"-1, 31" '"-2, 31' ' ' ' '-3; 31' ' ' ' ' '), wherein one or more conductors (20; 20a-20f - 20a ' ' ' ' '-20f ' ' ' ' ' ') are received in the receiving area, wherein the conductors (20, 20x; 20a-20f - 20a' ' ' ' ' '- 20f ' ' ' ' ' ') differ at least partly from each other.

2. Stator according to claim 1, wherein the conductors, viewed in a cross-section, differ in their shape and / or configuration.

3. Stator according to one of the preceding claims, wherein the conductors differ in an external shape, in particular a width and / or height, a design as a waveguide or solid conductor, a design as a single conductor or conductor bundle, and / or in the case of waveguides in a shape and / or a diameter of a channel.

4. Stator according to one of the preceding claims, wherein all conductors are designed as waveguides, in particular as waveguide I-pins.

5. Stator according to one of the preceding claims, wherein the receiving areas (31', 31'''-1, 31'''-2) are designed with trapezoidal flanks and / or with stepped flanks.

6. Stator according to one of the preceding claims, wherein the conductors (20, 20x; 20a-20f - 20a ' ' ' ' ' '-20f ' ' ' ' ' ' ) have a first end portion and a second end portion which are arranged on different sides of the stator core (30-30' ' ' ' ' ').

7. Stator according to one of the preceding claims, wherein the receiving area (31-31'; 31 ''-1, 31 ''-2; 31 '' '-1- 31" '-2; 31""-1, 31""-2; 31" '"-1, 31" '"-2, 31' ' ' ' '-3; 31' ' ' ' ') is designed as a slot, and the conductors in the receiving area are arranged such that a conductor arranged in the area of ​​a slot base of the receiving area provides a higher fill factor than a conductor arranged closer to an air gap of the stator.

8. Stator according to one of the preceding claims, wherein one or more of the conductors are formed as conductor bundles.

9. Stator according to one of the preceding claims, wherein end sections of the conductors (20, 20x; 20'; 20a-20f - 20a ' ' ' ' '-20f ' ' ' ' ') are connected, in particular in pairs, by means of a sleeve (15, 15x), wherein it is preferred that the sleeve (15, 15x) surrounds the end sections of the conductors (20, 20x; 20'; 20a-20f - 20a ' ' ' ' ' '-20f ' ' ' ' ' ' ).

10. Stator according to one of the preceding claims, wherein the conductors (20, 20x; 20'; 20a-20f - 20a ' ' ' ' ' '-20f ' ' ' ' ' ' ) have a rectangular cross-section.

11. Stator according to one of the preceding claims, wherein the conductors (20, 20x; 20'; 20a-20f - 20a ' ' ' ' ' '-20f ' ' ' ' ' ' ) are connected to a collector.

12. Stator according to claim 11, wherein a collector is provided at an opposite end of the stator core (SOSO' ' ' ' ' ') and the conductors are hydraulically connected in parallel.

13. Stator according to claim 11, wherein a collector for an inlet and an outlet of a coolant is arranged on a same side of the stator core (30-30'' '' '' '').

14. Stator according to claim 11, 12 or 13, wherein the collector (40') has a bump (45') arranged between conductors.

15. Stator according to one of claims 11-14, wherein the collector is formed from a potting compound which extends at least partially around the conductors.

16. Stator according to one of the preceding claims, wherein the waveguide(s) are arranged such that a fluid flows through the channels in parallel.

17. Stator according to one of the preceding claims, wherein the stator package has a plurality of radially arranged receiving regions (31 ''-1, 31 ''-2; 31 '' '-1, 31 '' '-2; 31""-1, 31""-2; 31" '"-1, 31" '"-2, 31" '"-3) which are separated from one another by a web.

18. Stator according to one of the preceding claims, wherein the coil unit has a helical or meandering course.

19. An electrical machine comprising a stator according to any one of the preceding claims.

20. Electrical machine according to claim 19, comprising a rotor of internal rotor design.

21. Electrical machine according to claim 19, comprising two rotors, in particular as a double rotor with mechanical coupling of both rotors.

22. A method for producing a stator, wherein the stator comprises at least one coil unit with a plurality of conductors (20, 20x; 20'; 20a-20f - 20a " " "-20f ' ' ' ' ' ' ), wherein at least one conductor is designed as a waveguide, wherein the conductors (20, 20'; 20a-20f - 20a' ' ' ' ' '- 20f ' ' ' ' ' ') differ at least partially from one another, comprising the steps: Providing a stator package (30-30' ' ' ' ') which has at least one receiving area (31-31'; 31 ' '-1, 31 ' '-2; 31 " '-1-31 " '-2; 31""-1, 31""-2; 31" '"-1, 31'""-2, 31"'"-3; 31' ' ' ' ' '), and Inserting the ladder (20, 20x; 20'; 20a-20f - 20a'" '"- 20f """) i nthe receiving area (31-31'; 31 ' '-1, 31"- 2; 31 " '-1-31 " '-2; 31""-1, 31""-2; 31" '"-1, 31" '"-2, 31"'"-3; 31' ' ' ' ' ') , wherein the conductors are electrically connected to one another in series.

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