WO2025157675A1 - Method for producing a stator of an electrical machine, and stator - Google Patents

Abstract

The invention relates to a method for producing a stator (10) for an electrical machine comprising a rotor and a stator (10), the stator (10) consisting of a sheet-metal stack having stator slots (4) between stator teeth (8) that extend along the axial direction (A) in the sheet-metal stack and radially (R) outwards 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 slots (4) together or in succession.

Description

Method for producing a stator of an electrical machine and stator

The invention relates to a method for producing a stator for an electrical machine with a rotor and stator, the stator consisting of a laminated core stack with stator slots between stator teeth, which extend along the axial direction in the laminated core stack and radially from the rotor axis, wherein conductors are prefabricated in a winding mat.

The invention also relates to a stator produced by the method.

State of the art

It is known to design such winding mats as so-called wave windings. Such a wave winding comprises several wave winding conductors, in which slot sections running in the slots of the stator are connected to head sections arranged in the region of the winding heads. In a radial flux machine with slots running in the axial direction of the stator, these slot sections are located alternately on both end faces of the stator carrier for each wave winding conductor, viewed in the circumferential direction. In this context, a stator carrier is understood to be the non-electromagnetically active part of the stator, for example a stator body without the field-generating coils. A stator body can in particular be designed as a stator laminated core consisting of stator laminations lying one above the other and electrically insulated from one another.

In an electrical machine with wave winding, parallel winding branches are often necessary per phase, since a wave winding uses a lower conductor height, especially compared to so-called hairpin windings, and thus the number of conductors in the slot is increased. To limit the induced phase voltage, several winding branches are connected in parallel.

DE 102020 120 849 B3 discloses a stator with a winding made 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 phase of the machine. Each wave winding conductor comprises slot sections that can be arranged in different radial positions within the stator slots. In addition, each wave winding conductor comprises head sections that each connect two slot sections outside the stator slots in the area of the winding heads. In a so-called wave winding, these head sections are arranged alternately at the two front ends of the stator for each wave winding conductor.

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 electrical machine, wherein the coil winding comprises a wire package consisting 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 that can be rotated about a rotation axis. According to the method, the wire package is fixed to a winding template, and winding heads are produced by displacing fixings of the wire package. The winding shaft is rotatable, so that after carrying out the method, a coil winding in the form of a wave winding is present, which has wires of the wire package pre-connected in pairs at one end.

The 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 close to the point where the heat is generated reduces the thermal resistance within the e-machine, which leads to higher continuous power and is therefore desirable.

However, the installation space in the stator is limited.

However, in the stator itself, due to the loss distribution in the winding conductors, the highest temperatures typically occur in the radially innermost conductor layers near the slot opening toward the air gap. The exposed location of the slot opening inside the electric machine makes positioning a structure for cooling purposes difficult.

DE 10 2021 109 437 A1 shows a stator with slots in which stator windings are inserted. The slots are closed radially inward using a slot closure device, a tube, bent into a cylinder.

From DE 10 2018 216 301 A1 the cylindrical rolling of cooling elements is known, whereby the cooling cylinder is inserted separately axially into the stator slots.

DE102014213506 A1 discloses a cooling device designed as a circumferential channel. It is mounted separately from the windings.

DE 10 2017 211 317 A1 also shows a prefabricated cylinder with cooling elements that were not prepared together with the winding.

DE 10 2020 102 778 A1 also shows a solution with separate cylindrical baskets.

The object of the invention is to create a novel stator cooling concept that combines the CWW winding mat technology with a cooling concept integrated into the slot of the stator. Description of the invention

The object is achieved by a method for producing a stator consisting of a laminated lamination stack with stator slots that extend along the axial direction in the laminated lamination 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 into a cylindrical structure and introduced together into the stator slots.

The underlying idea is to utilize the properties of CWW technology, namely the open slot geometry and the assembly process, which enables new ways to integrate cooling into the slot area. Furthermore, it is possible to combine two functions in the part that forms the slot closure: firstly, securing the winding in the stator slot and secondly, creating a volume for coolant flow.

In one embodiment, the cooling system component is connected to the winding mat prior to the rolling step.

The cooling system component has a meandering 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.

The advantage is that the winding mat and the cooling system component are inserted into the stator slots either radially or axially.

The cooling system component has noses that are guided in corresponding grooves of the stator teeth. In one embodiment, the cooling system components are clamped in the stator teeth and serve to fix the insulation of the stator slot.

The problem is also solved with a stator consisting of a lamination stack with stator slots that extend along the axial direction in the lamination stack and radially from the rotor axis, wherein the conductors are inserted according to the method described.

The invention enables direct cooling of the winding and stator teeth in the slot opening area. Cooling in this area can have a significant impact on performance, as a high proportion of iron losses occur in the stator area. Furthermore, the placement of cooling structures near the air gap has a positive effect on the thermal behavior of the rotor.

Description of the characters

Figure 1 shows a winding mat and a cooling system component with curved cooling channels,

Figure 2 shows a winding mat and a cooling system component with straight cooling channels,

Figure 3 shows a detailed view of the groove area with a locking wedge variant, incl.

Cooling channel for radial introduction,

Figure 4: Detailed view of the groove area with a locking wedge variant, including cooling channel for axial insertion in a possible configuration,

Figure 5: Detailed view of the groove area with a locking wedge variant.

Figure 1 shows a winding mat 2 made up of a plurality of electrical conductors 3 with rectangular cross-sections.

The winding mat 2 is manufactured with a conductor section 3a, which runs axially in stator slots 4 of a stator 10. On both sides of the straight axial run of the conductor section 3a, winding heads 3b are arranged at an angle to the conductor section 3a.

The winding mat 2 is completed as a band-like structure made up of a plurality of conductors 3.

In parallel, a cooling system component 5 with cooling channels is manufactured. Once the band-like structure of the winding mat 2 is completed, the cooling system component 5 is combined with the winding mat 2 in a first embodiment and firmly connected in a second embodiment.

The cooling system component 5 is available in two different embodiments.

The cooling system component 5 in Figure 1 is an embodiment with a meander-shaped plastic tube 6, which, like the conductors 3 used in the winding mat 2, has a rectangular or almost rectangular cross-section and is hollow.

The cooling system component 5 extends along the inner side 2a of the winding mat 2, i.e., the inner circumference of the stator. Figure 1 shows only a section of the cooling system component 5; the arrow perpendicular to the conductor sections 3a indicates the further course.

The connection to the winding mat 2 is established by placing it on the winding mat. It simply needs to be positioned so that the individual cooling channels fit between two conductors or on top of two conductors. The coiling takes place together, and it is important to prevent the cooling system components from shifting relative to the conductors. After being connected to the winding mat 2, the meandering cooling system component 5 is bent into a cylinder with it.

Alternatively, the winding mat 2 and the cooling system components 5 are rolled up together on a tool and inserted radially into the stator 10. The aforementioned tool has a cylindrical shape and carries the winding mat 2 and the cooling system components 5 with an integrated device which enables radial insertion into the stator 10. In this approach, the stator 10 has stator slots 4 in a shape as shown in Figs. 3a, 4a and 5a.

In another embodiment, a mechanical connection of the cooling system component 5 to the winding mat is established by gluing, either pointwise or over the entire surface, with an elastic material that only allows the positioning of the cooling system component 5 to the winding mat 2 during the winding process and insertion into the stator slots 4. For this purpose, the cooling system components 5 are fixed to the winding mat 2 with any type of adhesive, which is previously applied to the winding mat 2 or the cooling system components 5 in a separate step. The winding process described above then continues.

The meander-shaped cooling system component 5 has an inlet 5a and an outlet 5b. The meander-shaped cooling system component 5 can be integrally formed for a stator 10 or can consist of individual meander-shaped cooling system components 5, each with its own inlet 5a and outlet 5b.

An embodiment with rod-shaped cooling channels is shown in Figure 2. In this embodiment, the inlet 5a and the outlet 5b to the cooling channel are located on each individual rod-shaped cooling channel. After assembly, the rod-shaped cooling channels can be connected with their respective inlet and outlet to an annular channel or to other cooling channels present in the stator, or to each other.

The cooling system components 5 in the stator slots 4 must be tightly connected to allow an uninterrupted flow of fluid through the cooling system and to prevent leakage.

When using individual cooling channels, a connection to the winding mat is possible by clamping or a connection by gluing. In a further step, the winding mat 2 and those of the cooling system components 5 are inserted into the stator 10 and the stator slots 4, respectively.

For this purpose, the winding mat 2, together with the cooling system component 5, is inserted into the stator slots 4 from an open axial side of the stator 10. With this procedure, only one axial side of the stator 10 needs to be open. Alternatively, the combination of the winding mat 2 and the cooling system component 5 can be inserted by radially inserting it into the stator slots 4 after the winding mat 2 with the cooling system components 5 has been inserted as a cylinder into the central cavity of the stator 10.

Another possibility for inserting the cooling system component 5 with straight cooling channels, not according to the invention, is axial insertion into the stator slots 4 after the winding mat 2 has been radially inserted into the stator slots 4. Regardless of the insertion process of the cooling system component 5, the resulting conductor and cooling channel arrangement looks as shown in Figures 3-5.

Figure 3 shows a schematic section of a stator 10 in a radial sectional view with a stator tooth 8 and a stator slot 4. The stator slots 4 are provided with insulation 7. 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 towards the air gap of the stator 10. The stator teeth 8 have slots 9 near the inner circumference of the stator. A cooling channel of the cooling system component 5 has lugs 11 that are adapted to the shape of the slots 9 and engage in them.

Figure 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 Figure 5 shows that the cooling channel 6 holds the insulation 7 of the stator tooth 8.

By integrating assembly steps, the number of manufacturing process steps is reduced. Two crucial functions, the fixation of the winding mat 2 in the stator slot 4 and the cooling of the conductors 3, are integrated into a single component.

The dimensions of the slot must be adjusted so that the cooling system components can be accommodated in the slot opening.

The cooling system components 5 can be inserted radially and axially into the openings of the stator slots 4. The cooling system component 5 can be inserted simultaneously with the winding into the stator 10. 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 can be used in combination with the shut-off element of cooling system component 5.

The shape or dimensions of the cooling channel can be either dependent or independent of the groove width defined by the conductor dimensions.

Claims

Claims 1 . 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 together into the stator slots (4). 2. The method according to claim 1, wherein the cooling system component (5) is connected to the winding mat (2) before the rolling-up step. 3. The method according to claim 1, wherein the cooling system component (5) has a meandering cooling channel structure. 4. The method according to claim 1, wherein the cooling system component (5) consists of individual rod-shaped cooling channels. 5. The method according to claim 1, wherein the cooling system component (5) has at least one inlet (5a) and one outlet (5b) for cooling fluid. 6. Method according to one of the preceding claims, wherein the winding mat (2) and the cooling system component (5) are introduced either radially or axially into the stator slots (4). 7. Method according to one of the preceding claims, wherein the cooling system components have noses (11) which are guided in corresponding grooves (9) of the stator teeth (8). 8. Method according to one of the preceding claims, wherein the cooling system components (5) are clamped in the stator teeth (8) and serve to fix the insulation (7). 9. Stator (10) consisting of a laminated core stack with stator slots extending along the axial direction (A) in the laminated core stack and radially (R) from the rotor axis, wherein the conductors (3) are inserted according to the method according to one of claims 1-8.