Electrical machine stator

Abstract

The present invention relates to an electrical machine, in particular to a stator (10) for an electric motor or a generator. The stator (10) has a stator core with a plurality of stator slots (11). An electrical conductor (12) for forming a winding is disposed in the stator slots (11). At least a part of the stator (10), in particular the winding head connecting the electrical conductors (12), is formed by an additive manufacturing process. The electrical conductors (12) are inserted into the respective stator slots (11) in the radial direction in the cross-section of the stator (10) and extend in the longitudinal direction. In the present invention, the order of arrangement and type selection of the electrical conductors (12) is performed in the direction from the inner region to the outer region along the longitudinal direction of the stator.

Description

Summary of the Invention

[0001] The present invention relates to a stator of an electromechanical machine, in particular to a stator of an electric motor or a generator having a stator core. The stator core preferably has a plurality of stator grooves. Electric conductors forming the windings are arranged in the stator grooves, and at least a part of the stator, in particular the winding heads connecting the electric conductors, is formed by an additive manufacturing process. The electric conductors are preferably inserted into the respective stator grooves in the radial direction in the cross-section of the stator and extend in the longitudinal direction.

[0002] German Patent Specification No. 10 2021 119 405 discloses a stator for an electromechanical machine, a stator cooling system, and a method for cooling the stator.

[0003] The stator core has at least one stator groove, in which at least two, preferably at least four, electric conductors are arranged. At least a part of the stator is manufactured using an additive manufacturing process. In particularly powerful motors, a relatively high current flows through the conductors of the electric motor. As a result, heat is generated, and the efficiency of the machine decreases due to the specific resistance of the conductor material and, for example, the skin effect or proximity effect during alternating current operation.

[0004] In the field of high-performance motors, it is necessary to ensure appropriate stator cooling, for example, when used in the drive system of an electric vehicle.

[0005] As a well-known method of cooling, there is a method of surrounding the electric conductors of the stator with a heat conductor. As a further possibility, there is the following additive manufacturing process. That is, at least one cooling flow path to which a cooling fluid can be applied is formed for a predetermined number of electric conductors. At least two or at least four cooling flow paths not formed by the same electric conductor are fluidly connected in parallel.

[0006] The electrical conductor according to German Patent No. 10 2021 119 405 can preferably be designed as the individual winding conductors of a coil, so-called I-pins or U-pins or hairpins. The electrical conductor in the stator groove is arranged particularly in the radial cross-section of the stator perpendicular to the central axis of the stator. The electrical conductor arranged in the region inside the stator in the radial direction has the aforementioned cooling flow path. Thereby, it becomes possible to directly introduce the cooling force to the location where the heat generation is the largest in the stator groove and make it function as a heat sink.

[0007] International Publication No. 2023 / 006612 relates to a method for manufacturing a stator composed of windings, preferably hairpin windings, for an electromechanical device, particularly an electric motor or a generator. The purpose is to reduce the heat loss and electrical loss in the stator and reduce the installation space of the stator.

[0008] This particularly includes inserting a winding base into the groove of the stator and additionally applying at least one section of the winding head. In particular, it is applied by applying a laminated molding material in layers and locally selectively solidifying this laminated molding material by irradiation.

[0009] In this regard, the winding head has a connecting element manufactured using an additive process. Thereby, the envelope of the winding head, and thus the installation space, can be reduced or minimized. By this technology, the material changes and contact problems caused by welding can be reduced or avoided. The winding base body can vary in shape and / or cross-section and can be combined with the winding head in various ways.

[0010] In one embodiment, the cross-sectional area of each winding base is maximized for low frequencies. In this case, the stator grooves can be divided into segments running axially side by side. The corresponding winding bases each at least substantially completely fill the respective segments. In the case of high frequencies, the cross-section of each one or the basic winding body can be divided into at least two or three partial cross-sections. They are insulated from each other. In particular, it reduces the current displacement in the conductor caused by, for example, the skin effect and reduces the eddy current loss.

[0011] Generally, it is known that the current displacement in the grooves of an electromechanical device where a corresponding electrical conductor is provided as part of the winding varies. This depends on the operating mode of the corresponding machine and electrical physical mechanisms such as the so-called skin effect, proximity effect, eddy currents, etc. The current displacement increases with the increase in frequency and magnetic flux density. In high-performance machines, such losses must also be minimized, and it is not sufficient to suppress its influence only by cooling.

[0012] From the above, an object of the present invention is to provide an improved stator, particularly for electromechanical devices such as motors or generators. In particular, it is to create conditions for realizing or ensuring the highly efficient operation of a machine with a corresponding design. In particular, it reduces the increase in winding losses and significantly reduces the thermal load on the electrical conductors and their insulating materials used.

[0013] Here, the applicant's knowledge regarding the formation of twisting (twisting) partial conductors and dividing the cross-section over the active length to reduce the skin effect and prevent loop current is utilized. Also, the idea of shifting the twisting and layering of the partial conductors from the active region to the region of the winding head is utilized. This is particularly made possible by additive manufacturing techniques. By this measure, the groove region, particularly the cross-section of the groove, is optimally utilized, and the DC loss is reduced.

[0014] The object of the present invention is solved by a stator according to the combination of features according to claim 1. Its dependent claims represent at least advantageous designs and further improvements.

[0015] An electrical machine stator is envisaged. This is preferably a stator for an electric motor or a generator with a stator core. The stator core consists of a laminated core and an equivalent design with a large number of stator slots.

[0016] The electrical conductors forming the winding are arranged in the stator slots. At least part of the stator, in particular the winding heads connecting the electrical conductors, is realized by a well-known additive manufacturing process. The electrical conductors are inserted into the respective stator slots in the radial direction in the cross-section of the stator and extend in the longitudinal direction. In all stator slots or selected stator slots, multiple types of conductors are arranged (in the respective stator slots). Preferably (in the respective stator slots), different types of conductors are arranged so as to be located in the inner region (especially close to the longitudinal axis of the stator) rather than the outer region. For example, a stranded wire is located in the inner region, and a different type (i.e., not a stranded wire), for example, a solid metal, is located in the outer region.

[0017] Preferably, the selection of the arrangement order and type of the electrical conductors in all stator slots or selected stator slots is carried out in the direction from the inner region (oriented towards the longitudinal axis of the stator) to the outer region. This is carried out according to the expected current density of the electrical conductors located at a position radially away from the longitudinal axis of the stator. The radially varying current displacement is preferably considered here.

[0018] In particular, the above means means that in the radial direction in each groove, a specific type is used instead of basically the same design or the same type of electrical conductor.

[0019] Preferably, one or more stranded conductors or in particular twisted strands that fill grooves are arranged in or in the direction of the inner region (or elsewhere, in particular the grooves of the stator) towards the longitudinal axis of the stator.

[0020] In particular, preferably radially outside the stranded conductor(s) (or elsewhere, in particular within the stator grooves), rotationally split conductors and / or laminated strip conductors are arranged in layers. These are in particular functionally comparable to a Roebel bar.

[0021] Preferably, solid metal conductors, in particular profile wire solid copper conductors, are arranged in the respective stator grooves, in particular radially outside (or elsewhere, in particular within the stator grooves).

[0022] The stranded conductor can be composed of different conductor types, in particular different materials.

[0023] In one form, the stranded conductor can have a sheath based on a solid conductor. This solid conductor or solid conductor sheath can be formed by additive manufacturing (additive printing).

[0024] The rotationally split conductor is preferably composed of twisted individual conductors having different cross-sections. The wiring rearrangement of the individual conductors is realized in particular with a winding head in order to reduce DC losses.

[0025] At least part of the electrical conductor can be designed in a so-called hairpin shape. Alternatively, or additionally, it is also possible to use a Roebel conductor in which a plurality of individual conductors are bundled. A Roebel conductor is composed of several individual conductors that swap positions only once over the entire length of the conductor during the complete transposition length process. That is, it means that each conductor swaps positions within the winding coil. This is particularly important for minimizing AC losses and reducing coupling losses. A Roebel conductor usually has several (or a very large number of) complete transposition lengths and can carry a large current with a very large number of individual conductors.

[0026] The aforementioned strip conductor brings advantages to the machinery of the AC power supply. The aforementioned strip conductor is composed of at least two elongated rigid strip conductor elements and corresponding contact devices for current coupling and separation. The strip conductor element provides a current path. The strip conductor element is designed as a laminated structure with an electrical insulator sandwiched in between. Current coupling and separation are performed via the winding heads on one or both sides, particularly depending on the type of design where the shape of the conductor is U-shaped or I-shaped.

[0027] The strip conductor elements used are preferably laminated to each other. The strip conductor elements used exchange positions at least once over the entire length of the conductor during the complete transposition section process with respect to the laminated position. Preferably, the position exchange is achieved without twisting or torsion by complementary step jumps of the strip conductor elements, preferably by material forming.

[0028] The cross-sectional area shape of the strip conductor element changes in the step jump region. However, the cross-sectional area is preferably (substantially) constant in the step jump region where the cross-sectional area shape changes.

[0029] The cross-sectional area in the step jump region of the strip conductor element is preferably adapted to the cross-sectional area of other sections of the strip conductor element.

[0030] In particular, each of the step jumps has a recess complementary to the width side of the strip conductor element. As a result of the bonding of the laminations, they engage with each other.

[0031] The corresponding strip conductor is preferably composed of a laminated arrangement of at least two strip conductor elements having at least two step jumps. Each end of the strip conductor element is electrically connected.

[0032] The dimensions of the laminated arrangement are adapted to the dimensions of the electro-mechanical stator slots with respect to length and cross-section. The strip conductor can be part of a rectangular coil and / or a hairpin.

[0033] The strip conductor elements are preferably laminated without gaps, densely, with a thin insulating layer in between, or forming a compact arrangement.

[0034] The thickness of the insulating layer or layer thickness is preferably (many times) smaller than the thickness of the actual strip conductor element.

[0035] The strip conductor element is composed of a copper or copper alloy material or a solid material and / or is manufactured using additional techniques. Aluminum materials can also be used.

[0036] The strip conductor element used in laminated form according to the present invention to form a layer configuration will be described in more detail according to exemplary embodiments and FIGS. 1 and 2.

[0037] FIG. 1 shows a perspective view of a strip conductor device. The strip conductor element is an integrated one formed by joining two strip conductor elements according to the present invention. The two strip conductor elements are provided with an insulating layer formed to surround them.

[0038] FIG. 2 shows a side view of FIG. 1. In the process of joining two strip conductor elements, a strip conductor element device is manufactured by embedding an insulating layer with step jumps.

[0039] The strip conductor element device shown in the figure is composed of two strip conductor elements 1 and 2, which are laminated on each other.

[0040] During the passage of the complete inversion section VS, the positional relationship in the lamination of the strip conductor elements 1 and 2 is interchanged.

[0041] In the illustrated example, the strip conductor element 1 is located at the top in the left section of FIG. 1 and changes its position downward via the step SP.

[0042] For the strip conductor section 2, it is the opposite. As shown in FIG. 1, the position of the strip conductor section 2 changes from bottom to top via the step SP.

[0043] As shown in the illustration, it can be seen that the complementary step jumps SP of the strip conductor elements, for example by material forming, enable the position exchange of the strip conductor elements without causing torsion or twist.

[0044] The cross-sectional surface shape of the strip conductor elements 1 and 2 changes in the region of the step jump SP.

[0045] By forming in the region of the step jump SP, it is possible to keep the cross-sectional area (substantially) constant while changing the cross-sectional shape. Thereby, hot spots related to the current can be avoided.

[0046] The essence of the present invention is that the cross-sectional area in the region of the step jump SP is essentially adapted to the cross-sectional areas of the other sections of the strip conductor elements 1 and 2 and is designed to be the same if possible.

[0047] Each of the step jumps SP has a recess 3 complementary to the width side of the strip conductor element. As a result of the joining of the gaps, they are connected to each other (see FIG. 1).

[0048] The strip conductor device comprising two strip conductor elements 1 and 2 is manufactured by joining the strip conductor elements 1 and 2, preferably using a mechanical device. The two strip conductor elements 1 and 2 are firmly laminated without a gap and over their entire surfaces. The strip conductor element is based on the view of FIG. 1 from right to left. Thus, a compact arrangement is formed.

[0049] When using non-insulated strip conductor elements 1 and 2, a thin insulating layer 4 is inserted between the strip conductor elements 1 and 2 during the process of laminating the strip conductor elements 1 and 2 (see FIG. 2).

[0050] This insulating layer 4 may already be pre-formed with respect to the contour in the region of the step jump SP. Alternatively, the insulating layer 4 may be composed of the material forming the shape of the strip conductor elements 1 and 2 in the region of the step jump. This is done when the strip conductor elements 1 and 2 are joined and integrated.

[0051] The strip conductor elements 1 and 2 can be composed of solid copper or copper alloy materials. Thereby, effective and cost-effective production can be carried out. A solid strip material having a preferably rectangular cross-section is formed by a known and preferably used material forming process. The solid strip material is formed such that the relevant step jump SP is formed here. Obtaining the strip conductor element by joining the strip conductor elements 1 and 2 can be implemented by a simple automated method.

[0052] One of the advantages of this strip conductor device due to the non-linear conductor structure with step jumps is that when this strip conductor device is used in an electromechanical device, the area attacking the lateral groove field is reduced. Furthermore, the current displacement is minimized. By simply adapting the conductor shape, it is possible to correspond to different frequency spectra when operating the electromechanical device. The increase in current density in the region of the step jump can be reduced by shape adaptation and optimization.

[0053] When comparing the copper loss as a function of the conductor shape based on the known stranded conductor structure with the copper loss of the strip conductor device according to the present invention, the loss increase due to frequency dependence when using a strip conductor device having a laminated arrangement of strip conductor elements and step jumps is significantly reduced, particularly at high frequencies from 600 to 100 Hz.

[0054] Regarding the formation of the order of the array and the selection of the type of electrical conductor, the following exemplary embodiments will be described in more detail with reference to FIGS. 3 to 6.

[0055] FIG. 3 is a partial cross-sectional view of a rotor section related to a stator of an electromechanical device. FIG. 3 shows a groove diffusion field (dashed line) and various electrical conductors in the stator groove.

[0056] FIG. 4 is an explanatory diagram of current density. The current density varies due to current displacement in the groove of the electromechanical device. In FIG. 4, a region of very high current density in the direction of the rotor section and a region away from the rotor, i.e., a region of medium or lower current density in the outer direction, are shown.

[0057] FIG. 5 shows an exemplary embodiment of the selection of the type of electrical conductor. The selection of the type of electrical conductor aims at a loss reduction design of the winding. Near the rotor, i.e., inside, two layers of stranded conductors are arranged. Subsequently, two layers of conductors divided in the rotational direction follow. Further outside, two layers of solid conductors follow.

[0058] Figure 6 shows a schematic cross-sectional view of the arrangement of the electrical conductors. The arrangement of the electrical conductors is an arrangement from the inner region in the rotor direction towards the outside. Two layers of stranded conductors are arranged on the inner side. Subsequently, laminated strip conductors forming a laminated arrangement are arranged. Further thereafter, electrical conductors in the form of solid conductors follow.

[0059] Figures 3 to 6 show a part of the cross-section of the stator of the electrical machine. In the stator 10, an exemplary groove 11 is formed for accommodating the conductor 12 which is part of the winding.

[0060] The course of the resulting groove scattering field is indicated by the dashed line. A part of the rotor 13 of the electrical machine is also symbolically shown in the same way.

[0061] The resulting current density in each groove 11 is symbolically shown in the cross-sectional view of Figure 4. Near the rotor 13, i.e., in the direction of the virtual longitudinal axis of the stator, a high current density load 14 is expected. In the intermediate region, a medium current density 15 exists. In the outer region 16, the current density load is low and is not a problem.

[0062] The current density distribution shown in Figure 4 results from typically solid conductors (shown) that are mutually insulated and the corresponding wiring in the winding head not shown. According to the approach according to the present invention, an example of the selection of the special order and type of the arrangement of the electrical conductors in the stator groove 11 is represented in the cross-sectional views according to Figures 5 and 6. As shown in Figures 5 and 6, first, stranded conductors 17 (not shown) are arranged in the region facing towards the inside of the longitudinal axis of the stator.

[0063] Following these stranded conductors 17, sections of split rotary split conductors 18 follow. Further outwards, solid conductors 19 follow. In the embodiment shown in Figure 6, following the stranded conductors having a groove-like shape, strip conductors designed as laminated conductors forming a layer configuration 20 are arranged.

[0064] Following these strip conductors, solid conductors 19 are arranged.

[0065] The rotating split conductor 18 is formed by twisting together individual conductors having different cross-sections. The interconnection of the individual conductors is preferably realized in the winding head.

[0066] The strip conductor is a conductor formed by laminating strip conductor elements on top of each other. The strip conductor exchanges positions at least once over the entire length of the conductor during the process of a complete transposition section, with respect to the laminated position. The position exchange is realized without torsion or twist, by complementary step jumps of the strip conductor elements, and is preferably carried out by material shaping.

[0067] All of the different conductor types described above can be electrically contacted and connected in the winding head using additive printing technology, without the need for welding or crimping connections, and can be done without loss.

Brief Description of the Drawings

[0068]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

[0069] It should be noted that all of the components described above are claimed to be essential to the present invention, individually and in any combination, particularly with respect to the details shown in the drawings. Modifications thereof are well known to those skilled in the art.

[0070] Furthermore, it has been pointed out that the aim is to secure the broadest possible scope of protection. In this regard, the disclosure described in the claims can also be specified by the features described together with further features. This can be done without necessarily including these further features. It is clear that the brackets and the term "in particular" are intended to emphasize the optional nature of the features in their respective contexts. Conversely, it does not mean that the features are considered essential in the corresponding text without such specification.

Claims

1. A stator (10) for an electromechanical machine, in particular an electric motor or a generator, having a stator core, wherein the stator core has a plurality of stator grooves (11), an electrical conductor (12) for forming a winding is disposed within the stator grooves (11), at least a part of the stator (10), in particular the winding head connecting the electrical conductors (12), is formed by an additive manufacturing process, the electrical conductors (12) are inserted into respective stator grooves (11) in the radial direction in the cross-section of the stator (10) and extend in the longitudinal direction, the order of arrangement and type selection of the electrical conductors (12) within all or selected ones of the stator grooves (11) in the direction from the inner region to the outer region along the longitudinal direction of the stator is performed according to the current density, the current density is the current density expected for each electrical conductor (12) located at a radial distance from the longitudinal direction of the stator, a stator in which the radially varying current displacement is taken into account.

2. The stator according to claim 1, wherein one or more stranded conductors (17) having a groove filling shape are inserted in the direction of the inner region of the stator in the longitudinal direction.

3. The stator according to claim 2, wherein a rotary split conductor (18) or a laminated strip conductor (20) forming a layered arrangement is subsequently disposed along the radial direction outside the stranded conductor (17).

4. The stator according to claim 2 or claim 3, wherein a solid metal conductor, in particular a solid copper conductor (19), is disposed along the radial direction outside each of the stator grooves (11).

5. The stator according to claim 2, wherein the stranded conductor (17) is composed of different types of conductor materials.

6. The stator according to claim 2 or claim 5, wherein the stranded conductor (17) has a sheath based on a solid conductor.

7. The stator according to claim 6, wherein the sheath of the solid conductor is formed by additional pressing.

8. The rotary split conductor (18) is composed of twisted individual wirings having different cross-sectional areas, and the rearrangement of the wirings of the individual conductors is realized at the winding head.

9. The stator according to any one of the preceding claims, wherein at least a part of the electrical conductors is designed in a hairpin shape.

10. The strip conductor (20) is composed of elongated rigid strip conductor elements (1) and (2), The strip conductor elements (1) and (2) are laminated on each other, In the process of the full transposition section (VS), the strip conductor elements (1) and (2) are position-exchanged at least once over their conductor lengths with respect to their positions in the lamination, Furthermore, without causing torsion or twist, the position exchange is realized by complementary step jumps (SP) of the strip conductor elements (1) and (2), The stator according to any one of claims 3 to 8, wherein the position exchange is preferably performed by material forming.

11. The stator according to claim 10, wherein the cross-sectional surface shape of the strip conductor elements (1) and (2) changes in the region of the step jump (SP).

12. The stator according to claim 11, wherein the cross-sectional area is substantially constant in the region of the step jump (SP) where the cross-sectional area shape changes.

13. The stator according to claim 12, wherein the cross-sectional area in the region of the step jump (SP) conforms to the cross-sectional areas of other sections of the strip conductor elements (1) and (2).

14. Each of the step jumps has a recess (3) complementary to the width side of the strip conductor element, As a result of the bonding of the laminations, they fit together with each other. The stator according to any one of claims 10 to 13.

15. The lamination arrangement is composed of at least two strip conductor elements (1) and (2) having at least two step jumps (SP), The respective ends of the strip conductor elements (1) and (2) are electrically connected. The stator according to any one of claims 10 to 14.

16. The stator according to claim 15, wherein the lamination arrangement conforms to the dimensions of the grooves of the stator (10) of the electromechanical device with respect to the length and cross-sectional dimensions.

17. The stator according to any one of claims 10 to 16, wherein the lamination arrangement is part of a rectangular coil or a hairpin.

18. The strip conductor elements (1) and (2) are densely laminated over a wide area so as to form a dense and compact arrangement with a thin insulating layer (4) disposed therebetween without a gap. The stator according to any one of claims 10 to 17.

19. The stator according to claim 18, wherein the thickness or layer thickness of the insulating layer (4) is many times smaller than the thickness of the strip conductor elements (1) and (2).

20. The stator according to any one of claims 10 to 19, wherein the strip conductor elements (1) and (2) are made of solid copper or a copper alloy material or are manufactured using additive manufacturing techniques.

21. The stator according to any one of the preceding claims, wherein all different conductor types are electrically contacted and interconnected within the winding head by means of an additive printing technique without using welding or crimp connections.

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