Method for producing a stator of an electrical machine and stator

Abstract

Method for producing a stator (10) for an electrical machine with a rotor and stator (10), the stator (10) consisting of a laminated core stack with stator slots (4) between stator teeth (8) which extend along the axial direction (A) in the laminated core stack and radially (R) from the rotor axis, wherein conductors (3) are prefabricated in a winding mat (2) and wherein a cooling system component (5) consisting of at least one cooling channel is prefabricated, and the winding mat (2) and the cooling system component (5) are rolled up into a cylindrical structure and introduced into the stator slots (4) together or one after the other.

Description

The invention relates to a method for producing a stator for an electric machine with a rotor and a stator, the stator consisting of a sheet stack with stator grooves between stator teeth, which extend along the axial direction in the sheet stack and radially from the rotor axis, wherein conductors are prefabricated in a winding mat.The invention also relates to a stator which is produced by the method.Prior ArtIt is known to design such winding mats as a so-called wave winding. Such a wave winding comprises a plurality of wave winding conductors in which groove sections running in the slots of the stator are connected to head sections arranged in the region of the end windings. In a radial flux machine with slots running in the axial direction of the stator, these slot sections are located on both end sides of the stator carrier in an alternating manner when viewed in the circumferential direction in each wave winding conductor. In this context, a stator carrier is understood to mean the non-electromagnetically active part of the stator, that is to say, for example, a stator body without the field-generating coils. A stator body can be designed in particular as a stator laminated core which is formed from stator laminations which are situated one above the other and are electrically insulated from one another.In an electric machine with wave winding, parallel winding branches per phase are frequently necessary, since in particular in the case of wave winding a lower conductor height is used, in particular in comparison to so-called hairpin windings, and the number of conductors in the slot is thus increased. In order to limit the induced phase voltage, a plurality of winding branches are connected in parallel.DE 10 2020 120 849 B3 discloses a stator having a winding of winding mats. At least one winding mat is arranged in the stator slots. This winding mat is designed as a distributed winding. It contains two sets of continuous wave winding conductors for each strand of the machine. Each wave winding conductor comprises slot portions that can be arranged in different radial positions within the stator slots. In addition, each wave winding conductor comprises head sections which respectively connect two slot sections outside the stator slots to one another in the region of the winding heads. In a so-called wave winding, these head sections in each wave winding conductor are arranged alternately at the two end-face ends of the stator.DE 10 2019,117 966 A1 discloses a method for producing a coil winding for insertion into radially open slots in a rotor or stator of an electric machine, wherein the coil winding has a wire package which consists of a number of wires, wherein the wires of the wire package run parallel to one another and are connected to one another in pairs at one end of the wire package, and wherein the coil winding is formed by a flat winding template which is rotatable about an axis of rotation. According to the method, the wire package is fixed on a winding jig and end windings are generated by displacing fixations of the wire package. The winding shaft is rotatable, so that after carrying out the method, a coil winding is present in the form of a wave winding which has wires of the wire package preconnected in pairs at one end.This compact design of modern electric e-machines with high power density makes cooling in the e-machine a challenge.Direct cooling of e-machine components near the location where the heat is generated reduces thermal resistances within the e-machine, leading to higher continuous performance and therefore desirable. However, the installation space in the stator is limited.However, particularly in the stator, the highest temperatures typically occur in the radially innermost conductor layers close to the slot opening toward the air gap because of the loss distribution in the conductors of the winding. The exposed location of the groove opening inside the e-machine makes positioning of a structure difficult for cooling purposes.It is the object of the invention to create a novel stator cooling concept which combines the winding mat technology CWW with a cooling concept integrated into the slot of the stator.DESCRIPTION OF THE INVENTIONThe object is achieved by a method for producing a stator consisting of a sheet stack with stator grooves which extend along the axial direction in the sheet stack and radially from the rotor axis, wherein conductors for a winding mat are prefabricated and wherein a cooling system component consisting of cooling channels is prefabricated, and the winding mat and the cooling system component are rolled up to form a cylindrical structure and introduced into the stator grooves together or one after the other.The underlying idea is to use the properties of CWW technology, namely the open groove geometry and the assembly process, which enables new ways of integrating the cooling into the groove area. Moreover, it is possible to combine two functions in the part forming the slot closure: on the one hand, the fixing of the winding in the stator slot and, on the other hand, the creation of a volume for the coolant flow.The cooling system component is connected to the winding mat prior to the coiling step.The cooling system component has a meander-like cooling channel structure or consists of individual rod-shaped cooling channels.The cooling system component has at least one inlet and one outlet for cooling fluid.It is advantageous that the winding mat and the cooling system component are introduced either radially or axially into the stator slots.The cooling system component has noses which are guided in corresponding grooves of the stator teeth.In one embodiment, the cooling system components are braced in the stator teeth and serve for fixing the insulation of the stator slot.The object is also achieved with a stator consisting of a sheet stack with stator grooves which extend along the axial direction in the sheet stack and radially from the rotor axis, wherein the conductors are introduced according to the method described.The invention enables direct cooling of the winding and of the stator teeth in the region of the slot opening. The cooling in this region can have a considerable effect on the power, since a high proportion of the iron losses is in the stator region. Moreover, the placement of cooling structures near the air gap positively affects the thermal behavior of the rotor.DESCRIPTION OF THE FIGURESFIG. 1 shows a winding mat and a cooling system component with curved cooling channels, FIG. 2 shows a winding mat and a cooling system component with straight cooling channels, FIG. 3 shows a detailed view of the groove region with a locking wedge variant, including. cooling channel for radial insertion, FIG. 4 : detailed view of the groove region with a locking wedge variant, including. cooling channel for axial introduction in a possible configuration, FIG. 5 : Detailed view of the groove region with a locking wedge variant.FIG. 1 shows a winding mat 2 made of a plurality of electrical conductors 3 with rectangular cross sections.The winding mat 2 is produced with a conductor section 3 a, which runs axially in stator slots 4 of a stator 10. Winding heads 3 bare arranged on both sides of the straight course of the conductor section 3 a.The winding mat 2 is finished as a band-like structure.In parallel, a cooling system component 5 with cooling channels is produced. Once the strip-like structure of the winding mat 2 is finished, the cooling system component 5 is brought together with the winding mat 2 and possibly firmly connected.The cooling system component 5 is in FIG. 1 a meandering plastic tube 6, which likewise has a rectangular or nearly rectangular cross section and is hollow.The cooling system component 5 extends along the inner side 2 aof the winding mat 2, i.e. the inner periphery of the stator. FIG. 1 shows only a section of the cooling system component 5; the arrow perpendicular to the conductor sections 3 aindicates the further course. The meandering cooling system component 5 is bent into a cylinder after its connection to the winding mat 2.The meandering cooling system component 5 has an inlet 5 aand an outlet 5 b. The meandering cooling system component 5 can be integral for a stator 10 or can consist of individual meandering cooling system components 5 with their own inlet 5 aand outlet 5 b, respectively.An embodiment with rod-like cooling channels is shown in FIG. 2. In this embodiment, the inlet 5 aand the outlet 5 bto the cooling channel are located at each individual rod-like cooling channel. After assembly, the rod-like cooling channels can be connected with their respective inlet and outlet to an annular channel or further cooling channels present in the stator or to one another. The cooling system components 5 in the stator grooves 4 must be tightly connected in order to allow undisturbed flow of liquid through the cooling system and to prevent leaks.In a further step, the mat and the cooling channels are inserted into the stator 10 or the stator grooves 4.For this purpose, the winding mat 2 together with the cooling system component 5 is inserted into the stator grooves 4 from an open axial side of the stator 10. In this approach, only one axial side of the stator 10 needs to be open. Alternatively, the combination of winding mat 2 and cooling system component 5 is introduced by radially inserting it into the stator slots 4 after the winding mat 2 with the cooling system components 5 is inserted as a cylinder into the central cavity of the stator 10.A further possibility for introducing the cooling system component 5 with straight cooling channels is the axial introduction into the stator grooves 4 after the winding mat 2 has been introduced radially into the stator grooves 4. Regardless of the process of introducing the cooling system component, the resulting conductor and cooling channel arrangement looks as shown in FIGS. 3-5.FIG. 3 shows a schematic section of a stator 10 in a radial sectional view with a stator tooth 8 and a stator groove 4. Eight conductors 3 are arranged in the stator slot 4 along the longitudinal axis of the stator 10. The conductors 3 have a rectangular cross section. The stator slot 4 is open toward the air gap of the stator 10. The stator teeth have slots 9 near the inner periphery of the stator. A cooling channel of the cooling system component 5 has noses 11 which are adapted to the groove shape of the grooves 9 and engage with them.FIG. 4 shows an alternative embodiment, with angled noses 11 on the cooling channel 6, which engage in corresponding grooves 9 of the stator tooth 8.The embodiment of FIG. 5 shows that the cooling channel 6 holds the insulation 7 of the stator tooth.The integration of assembly steps reduces the number of manufacturing process steps. Two decisive functions, the fixing of the winding mat 2 in the stator slot 4 and the cooling of the conductors 3, are integrated in one component.The dimensions of the slot must be adjusted so that the components of the cooling system can be accommodated in the slot opening.The radial and axial insertion of the cooling system components 5 into the openings of the stator grooves is possible. The insertion of the cooling system component can take place together with the insertion of the winding into the stator. The number of serial and parallel cooling channels is freely selectable and independent of the type of cooling medium used and the material of the cooling components. An advantageous solution is to use the same number of cooling channels as stator slots 4.Additional shut-off elements may be used in combination with the shut-off element of the cooling system component 5.The shape or the dimensions of the cooling channel can be dependent on the slot width defined by the conductor dimensions as well as independent.References included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedDE 10 2020 120 849 B3

[0005] DE 10 2019,117 966 A1

[0006]

Claims

Method for producing a stator (10) for an electric machine with a rotor and a stator (10), the stator (10) consisting of a sheet stack with stator grooves (4) between stator teeth (8) which extend along the axial direction (A) in the sheet stack and radially (R) from the rotor axis, wherein conductors (3) are prefabricated in a winding mat (2) and wherein a cooling system component (5) consisting of at least one cooling channel is prefabricated, and the winding mat (2) and the cooling system component (5) are rolled up to form a cylindrical structure and introduced into the stator grooves (4) together or one after the other.Method according to claim 1, wherein the cooling system component (5) is connected to the winding mat (2) before the winding step.Method according to claim 1, wherein the cooling system component (5) has a meander-like cooling channel structure.Method according to claim 1, wherein the cooling system component (5) consists of individual rod-shaped cooling channels.Method according to claim 1, wherein the cooling system component (5) has at least one inlet (5a) and one outlet (5b) for cooling fluid.Method according to any of the preceding claims, wherein the winding mat (2) and the cooling system component (5) are introduced either radially or axially into the stator grooves or in a combination of radial and axial steps.Method according to any of the preceding claims, wherein the cooling system component comprises noses (11), which are guided in corresponding grooves (9) of the stator teeth (8).Method according to one of the preceding claims, wherein the cooling system components (5) are braced in the stator teeth (8) and serve for fixing the insulation (7).A stator (10) consisting of a sheet metal stack with stator grooves which extend along the axial direction (A) in the sheet metal stack and radially (R) from the rotor axis, wherein the conductors (3) are introduced according to the method according to one of claims 1 - 8.

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