DISTRIBUTED WINDING PROCESS WITH SIMULTANEOUS AND DIRECT INSERTION OF COILS WITHOUT RELAY TOOLING

Abstract

DISTRIBUTED WINDING METHOD WITH SIMULTANEOUS AND DIRECT INSERTION OF COILS WITHOUT RELAY TOOLING The invention relates to a distributed winding method for a stator comprising a star-shaped central portion having at least six teeth separated by notches, each intended to receive conductors of a coil, characterized in that it comprises a first step (110) of simultaneously inserting a first portion of N conductors directly into the N notches, via an opening in each notch arranged opposite the central portion, a step (112) of rotating the portions of the N conductors at the coil heads, a second step (114) of simultaneously inserting a second portion of the N conductors directly into a different and non-adjacent notch via the opening in each notch arranged opposite the central portion, and a step (118) of closing the notches by inserting a cylindrical portion around the central portion of the stator.Figure for the abridged version: Fig. 5.

Description

Title of the invention: DISTRIBUTED WINDING METHOD WITH SIMULTANEOUS INSERTION AND DIRECT REELS WITHOUT RELAY TOOLS Technical field of the invention

[0001] The invention relates to a distributed winding method. In particular, the invention relates to a distributed winding method for a stator of an electrical machine such as an electric motor or an electric generator, allowing direct winding without the need for relay tools. Technological background

[0002] The methods for manufacturing stators of electrical machines such as electric motors or electric generators are very numerous and particularly linked to the topology of the windings on the one hand, and the architecture of the magnetic circuit and the form factor on the other. These topologies are directly linked to the desired technical and industrial performance.

[0003] In the prior art, many solutions have been put in place to adapt to the specific constraints of each application in order to meet various constraints such as technical performance, compactness, number of phases, lifespan, long-term economic performance, speed and industrialization costs of electrical machines.

[0004] In addition, electrical machines used in demanding environments (aeronautics or space for example) have recently seen supply voltages and switching frequencies evolve, which has required the use of new materials as well as perfect control of the insulation between phases and between turns in order to push back the voltages of appearance of partial discharges likely to degrade the electrical insulation and consequently, the life of the electrical machine.

[0005] The combination of factors such as increased voltage levels, increased switching frequency and reduced size of electrical machines constitute, particularly when combined, the current source of industrial feasibility, cost and reliability problems.

[0006] Identified prior art solutions to address these constraints have included, for example, modifications: - In the type of conductor used, with the use of continuous rigid bar windings whose position is controlled, providing a system compact and allowing the elimination of connections on the opposite side to the insertion of the bars, or the use of Litz wires, - In the winding typology, with a wave winding, - In winding processes (tooling used, forming, compaction, etc.).

[0007] However, current solutions have several disadvantages.

[0008] One disadvantage is that these distributed winding solutions all require the use of specific tooling, called relay tooling, on which the winding is performed. Once the winding is installed on the relay tooling, the latter is used to insert it into the stator slots, generally from inside the stator, that is, by translation from the stator axis to the outside of the stator. Furthermore, this internal winding solution is more complex on stators with small inner diameters, particularly the stators of high-speed electrical machines.

[0009] In addition, current winding solutions using rigid bars or continuous Litz wires are problematic when the machine includes a small number of poles (1 to 2 pole pairs), in particular because they generate dimensional handicaps, notably conductor overlengths appearing at the coil heads.

[0010] The inventors therefore sought an alternative solution enabling a distributed winding process that does not require relay tooling, and is particularly suited to the stator of high-speed electrical machines with a small inner diameter. Objectives of the invention

[0011] The invention aims to provide a distributed winding method for a stator for an electrical machine which overcomes the disadvantages of the prior art, the distributed winding being either of the turns winding type or of the wave winding type.

[0012] The invention aims in particular to provide, in at least one embodiment, a distributed winding method for a stator that does not require relay tooling.

[0013] The invention aims in particular to provide, in at least one embodiment, a distributed winding method for a stator allowing direct winding on the stator.

[0014] The invention aims in particular to provide, in at least one embodiment, a distributed winding method for a stator enabling the production of high-speed electrical machines.

[0015] The invention aims in particular to provide, in at least one embodiment, a distributed winding method for a stator particularly suited to stators with a small inner diameter.

[0016] The invention aims in particular to provide, in at least one embodiment, a distributed winding method for a stator particularly suited to stators with a low number of pole pairs.

[0017] The invention aims in particular to provide, in at least one embodiment, a distributed winding method for a stator facilitating the deterministic placement of conductors in the stator slots.

[0018] The invention aims in particular to provide, in at least one embodiment, a distributed winding method for a stator that facilitates phase isolation. Description of the invention

[0019] To this end, the invention relates to a distributed winding method for a stator for an electrical machine, said stator comprising a central part in the shape of a star around an axis and comprising at least six teeth separated by gaps forming N notches, each intended to receive conductors of a coil associated with a phase of the stator, and a cylindrical part surrounding the central part, characterized in that it comprises: - a first step of simultaneous insertion of a first portion of N conductors from each stator phase directly into the N slots intended to receive said conductors, the insertion being carried out via an opening in each slot arranged opposite the axis of the central part, - a step involving the rotation of the portions of the N conductors not inserted at the coil heads, - a second step of simultaneous insertion of a second portion of the N conductors of each stator phase directly into the N slots, each conductor being inserted into a different and non-adjacent slot from the slot into which said conductor was inserted in the first insertion step, the insertion being carried out via the opening of each slot arranged opposite the axis of the central part, - a step of closing the notches by inserting the cylindrical part around the central part of the stator

[0020] A winding method according to the invention thus allows for the creation of a distributed winding directly on the stator, without requiring any relay tooling. This is made possible by the use of a star-shaped central portion that allows winding directly into the slots from the outside, and by the simultaneous insertion of the conductor segments into all the slots simultaneously. The star-shaped central portion and the cylindrical portion form the magnetic circuit of the stator. The term "conductor" refers to a wire of conductive material intended to form the coil. The term "wire" can also be used to refer to a conductor.

[0021] "Simultaneous" means the insertion of conductors into all the slots during a single operation, within a limited time interval, for example, one second or less, unlike sequential slot-by-slot insertion, without implying that the conductors must be inserted at precisely the same instant. Furthermore, simultaneous insertion consists of inserting all phases at the same time, and not phase by phase or coil by coil as is generally the case in the prior art, with coils pre-formed on tooling and then inserted into the central star of the stator. Since the number of teeth is greater than or equal to six, the number N of slots is equal to the number of teeth and also greater than or equal to six.

[0022] Insertion via the opening arranged opposite the axis of the central part can be achieved, according to a first embodiment, by translating each conductor from outside the slot in a direction substantially perpendicular to the stator axis and towards the stator axis. According to another embodiment, insertion can be achieved by directly unwinding the conductor into the slot, using a winding tool extending through the opening and moving along the slot. The opening arranged opposite the axis of the central part is thus an external opening allowing winding directly into the slots from the outside.

[0023] The simultaneous insertion of the conductor portions makes it possible in particular to obtain geometric paths of the conductors in the slots of the magnetic circuit as well as from one slot to another which are identical for all the conductors with respect to the position of the slots in which they must be inserted in order to control their position.

[0024] The term "directly" refers to the insertion of the conductor portion into the stator slot without using a relay tool on which the complete winding would be carried out, as is the case in the prior art. The winding, in the direction of unwinding the conductor to form a coil by winding it around an element, here in the central part of the stator via two slots, is carried out on the stator, unlike the prior art where the coils are formed by unwinding on a relay tool in order to be inserted in a single operation into the stator once the entire coil has been formed.

[0025] The second insertion is made in a different and non-adjacent notch from the notch in which said conductor was inserted in the first insertion step so as to obtain a distributed winding, unlike a concentric winding where the conductor is wound around a single tooth, i.e. in two adjacent notches around said tooth.

[0026] Advantageously and according to the invention, the first insertion step, the rotation step and the second insertion step are repeated at least once before the notch closing step, so as to obtain a distributed winding with turns or a wavy winding composed of several turns for each coil around two notches among the N notches.

[0027] According to this aspect of the invention, the insertion and rotation steps are repeated until the desired number of turns for the winding is obtained. The number of repetitions depends on the shape and size of the slots, the thickness of each turn, the slot filling rate, the desired characteristics and performance, etc. The length and shape of the turns forming the winding change as the conductor portions are integrated into the magnetic circuit formed by the central part, following a predefined path. The turns can be formed from a winding of simple strands comprising a single conductor or from parallel strands comprising several conductors wound together. A phase can be formed from a single coil or from several coils connected in parallel and / or in series.

[0028] Advantageously and according to the invention, the method includes at least one step of adding at least one retaining and / or guiding piece for the portions of conductors arranged outside the notches.

[0029] According to this aspect of the invention, these intermediate pieces allow for better control of the conductor paths, particularly at the coil heads. These retaining or guiding pieces can be placed temporarily on the stator during the winding process, or permanently on the stator, thus remaining on the stator as manufactured.

[0030] Advantageously and according to the invention, the process includes at least one step of inserting insulation between at least two phases.

[0031] According to this aspect of the invention, the distributed winding process allows for the easy addition of insulators between the phases and / or between the phases and ground, the insertion of the conductor portions being able to be interrupted at various preselected times in order to deposit additional insulators between the phases and / or between the phases and ground.

[0032] Advantageously and according to the invention, the steps of inserting the portions of conductors can be interrupted at different preselected times in order to deposit various control systems such as position sensors, winding temperature sensors, cooling aid elements (for example a pipe allowing a fluid to circulate inside the notches between the conductors), etc.

[0033] Advantageously and according to the invention, the cylindrical part is monobloc and directly surrounds all the notches of the stator.

[0034] According to this aspect of the invention, the cylindrical part is formed from a single piece directly surrounding the central star-shaped part to close the notches.

[0035] Advantageously and according to the invention, the cylindrical part comprises a plurality of angular segments, and the method includes a step of inserting each angular segment between two teeth of the stator so as to close at least one notch.

[0036] According to this aspect of the invention, the cylindrical part is divided into several angular segments, making it possible, in particular, to eliminate the dimensional constraints of the stator related to the axial mounting of the star-shaped central part in the cylindrical magnetic yoke. Specifically, it is possible to apply an angle to the conductor exiting the slot at the coil heads and, consequently, to further reduce the axial size of the coil heads.

[0037] Advantageously and according to the invention, the cylindrical part comprises N angular segments, and the method includes a step of inserting each angular segment between two teeth of the stator so as to close at least one notch.

[0038] According to this aspect of the invention, the cylindrical part comprises as many angular segments as there are notches to be closed, and each angular segment closes a notch.

[0039] Advantageously and according to the invention, the central part comprises on the one hand a cylindrical portion comprising N slots distributed on the outer surface of the cylindrical portion, and on the other hand N independent teeth, and in that the process comprises a manufacturing step of the central part by inserting each independent tooth into a slot of the cylindrical portion.

[0040] According to this aspect of the invention, each tooth is independent, which can simplify the manufacture of the central part of the stator. The central structure housing the teeth can be made of a different material, for example thermoplastic, making it possible to completely eliminate the short circuit between the stator teeth at the air gap of the electrical machine.

[0041] Advantageously and according to the invention, the process includes, following the notch closing step, a compression and / or shaping step of the coil heads according to a predetermined shape.

[0042] According to this aspect of the invention, shaping and compression are facilitated by better control of the shape of the coil heads thanks to the simultaneous insertion and rotation of the conductors in all the notches, the conductors all forming identical paths on the stator.

[0043] Advantageously and according to the invention, the conductors are Litz wires.

[0044] Advantageously, and according to another embodiment of the invention, the conductors are more generally parallel strand conductors, pre-formed or not, braided or not.

[0045] According to this aspect of the invention, parallel strand conductors such as Litz wires are particularly suitable in this type of winding since they have a flexibility and a more controlled shape which allows control of the filling of the slots and the path of the conductors during winding.

[0046] The invention also relates to tooling for carrying out a distributed winding method of a stator for an electrical machine, said stator comprising a central part in the shape of a star around an axis and comprising at least six teeth separated by empty spaces forming N notches each intended to receive conductors of a coil associated with a phase of the stator, and a cylindrical part surrounding the central part, characterized in that it comprises a means for simultaneously unwinding N conductors intended to be inserted into the N notches, a means for distributing the N conductors so as to arrange each conductor opposite the notch into which a portion of the conductor is to be inserted, a means for inserting each portion of the conductor into said notch, and a means for rotating the stator relative to the tooling or the stator relative to the tooling for the rotation of the conductors at the coil heads.

[0047] Advantageously, the tooling according to the invention is configured for carrying out a winding process distributed by turn or by corrugated winding according to the invention.

[0048] Advantageously, the distributed winding process according to the invention is configured to be carried out by tooling according to the invention.

[0049] The invention also relates to a distributed winding stator, characterized in that the distributed winding was achieved by a distributed winding process according to the invention.

[0050] The invention also relates to a distributed winding method, tooling for carrying out a winding method, and a distributed-winding stator characterized in combination by all or part of the features mentioned above or below. List of figures

[0051] Other objects, features and advantages of the invention will become apparent from the following description, given by way of non-limiting example only, and which refers to the accompanying figures in which:

[0052] [Fig-1] is a schematic view of a central part of a stator as used for the implementation of the winding process according to an embodiment of the invention,

[0053] [Fig.2] is a schematic view of an intermediate manufacturing step of a part stator central by inserting each tooth into a substantially cylindrical central structure, of a winding process according to an embodiment of the invention,

[0054] [Fig.3] is a schematic view of a central part of a stator comprising a winding put in place by a winding process according to an embodiment of the invention,

[0055] [Fig.4] is a schematic view of a final insertion step of each angular segment between two stator teeth according to a winding process according to an embodiment of the invention,

[0056] [Fig.5] is a schematic view of a winding process according to an embodiment of the invention,

[0057] [Fig.6] is a schematic side view of a stator being wound by a winding process according to an embodiment of the invention,

[0058] [Fig.7] is a schematic front view of a stator being wound by a winding process according to an embodiment of the invention.

[0059] Detailed description of an embodiment of the invention

[0060] In the figures, the scales and proportions are not strictly respected for the purposes of illustration and clarity.

[0061] In addition, identical, similar or analogous elements are designated by the same references in all figures.

[0062] Fig. 1 schematically represents a central part of a stator 10 as used for implementing the winding process according to an embodiment of the invention.

[0063] The central part 12 in the shape of a star around an axis comprises N teeth, at least six teeth, here twelve teeth 14 separated by empty spaces forming N notches, here twelve notches 16 each intended to receive conductors of a coil associated with a phase of the stator.

[0064] Figure 2 schematically represents an intermediate step in the manufacture of a central stator portion by inserting each tooth into a substantially cylindrical central structure, of a winding process according to an embodiment of the invention. In this embodiment, the central stator portion 10 comprises, on the one hand, a cylindrical portion 18 having N slots, here twelve slots 20 distributed over the outer surface of the cylindrical portion 18, and on the other hand, N independent teeth, here twelve independent teeth 14, four of which are inserted and a fifth 14a is being inserted, the central portion being manufactured by inserting each independent tooth 14 into a slot 20 in the cylindrical portion 18.

[0065] Figure 3 schematically represents a central stator portion 12 comprising a winding 22 assembled by a winding process according to an embodiment of the invention. The winding 22 comprises, in a known manner, several phases, here three phases 22a, 22b, 22c, each composed of one or more coils of conductors wound around the slots. The winding 22 is here a distributed winding. A particular feature is that, at this stage of stator manufacturing, the slots are opened externally after the insertion of the conductors through external openings 24 formed by the slots, located opposite the stator axis.

[0066] Figure 4 schematically represents a final stage of insertion of an angular segment between two stator teeth according to a winding method according to an embodiment of the invention. The angular segments 26 thus close the notches at the openings 24 around the winding 22 and thereby form a cylindrical part 28 surrounding the central part 12. The stator 10 is thus completed.

[0067] Figure 5 schematically represents a distributed winding method 100 according to an embodiment of the invention. The method 100 allows, in particular, the distributed winding of a stator for an electrical machine as schematically represented in Figures 1 to 4, that is to say, the winding of a stator comprising a central part in the shape of a star around an axis and comprising at least six teeth separated by gaps forming N slots, each intended to receive conductors of a coil associated with a phase of the stator, and a cylindrical part surrounding the central part.

[0068] The winding process 100 comprises: - a first step 110 of simultaneous insertion of a first portion of N conductors of each stator phase directly into the N slots intended to receive said conductors, the insertion being carried out via an opening of each slot arranged opposite the axis of the central part, - a step 112 of rotation of the portions of the N conductors not inserted at the coil heads, - an optional step 114 of inserting insulation between at least two phases, or of inserting various control systems such as position sensors, winding temperature sensors, cooling aid elements (for example a pipe allowing a fluid to circulate inside the slots between the conductors), etc. - a second step 116 of simultaneous insertion of a second portion of the N conductors of each stator phase directly into the N slots, each conductor being inserted into a different and non-adjacent slot from the slot into which said conductor was inserted in the first insertion step, the insertion being carried out via the opening of each slot arranged opposite the axis of the central part, either by translation of each conductor from outside the slot in a direction substantially perpendicular to the stator axis and towards the stator axis, or by direct unwinding of the conductor directly from the slot, via an unwinding tool extending through the opening and moving along the slot, - a step 118 of closing the notches by inserting the cylindrical part around the central part of the stator

[0069] Steps 110 to 116 can be repeated as many times as necessary to obtain a distributed winding composed of several turns made by windings by turns or wavy windings for each phase around two slots among the N slots.

[0070] The process may also include additional preliminary or final steps.

[0071] For example, the process may include, where the central part is formed of independent teeth as shown in [Fig.2], a preliminary step 120 of manufacturing the central part by inserting each independent tooth into a slot in the cylindrical portion.

[0072] The method may also include a preliminary step 122 of adding at least one retaining and / or guiding piece for the conductor portions arranged outside the slots. Such retaining and / or guiding pieces for the conductor portions are shown, for example, in Figures 6 and 7, which schematically represent, respectively from the front and side, a stator being wound by a winding method according to an embodiment of the invention.

[0073] The retaining and / or guiding parts 30 are represented here by nails that hold and guide the conductors 32 forming the winding. Once all the conductors are inserted simultaneously into the slots of the winding, rotation winds the conductors around the retaining and / or guiding parts to allow for a second insertion. The retaining and / or guiding parts 30 can be removed once the winding is complete.

[0074] The method may also include, following the notch closing step, a step 124 of compressing and / or shaping the coil heads according to a predetermined shape. The compression step 124 makes it possible, in particular, to obtain a predetermined shape that can be constrained in terms of volume and angular arrangement (for example, to limit the angular protrusion of the stator conductors at the coil head).

Claims

Demands

1. A method for the distributed winding of a stator (10) for an electrical machine, said stator comprising a central star-shaped portion (12) about an axis and comprising at least six teeth (14) separated by gaps forming N slots (16), each intended to receive conductors of a coil (22) associated with a phase of the stator, and a cylindrical portion (28) surrounding the central portion, characterized in that it comprises: • a first step (110) of simultaneously inserting a first portion of N conductors (32) of each stator phase directly into the N slots (16) intended to receive said conductors, the insertion being carried out via an opening (24) of each slot arranged opposite the axis of the central portion, • a step (112) of rotating the portions of the N conductors (32) not inserted at the coil heads,• a second simultaneous insertion step (114) of a second portion of the N conductors (32) of each stator phase directly into the N slots, each conductor being inserted into a different and non-adjacent slot from the one into which said conductor was inserted in the first insertion step, the insertion being carried out via the opening (24) of each slot arranged opposite the axis of the central part, • a step (118) of closing the slots (16) by inserting the cylindrical part (28) around the central part (12) of the stator.

2. A method for distributing the winding of a stator according to claim 1, characterized in that the first insertion step, the rotation step and the second insertion step are repeated at least once before the slot closing step, so as to obtain a distributed winding (22) composed of several turns for each phase around two slots among the N slots made by turns or wavy windings.

3. A distributed winding method for a stator according to any one of claims 1 to 2, characterized in that it comprises at least one step (122) of adding at least one part (30) for holding and / or guiding the portions of conductors arranged outside the notches.

4. A distributed winding method of a stator according to any one of claims 1 to 3, characterized in that it comprises at least one step (116) of insulating insertion between at least two phases.

5. Distributed winding method of a stator according to any one of claims 1 to 4, characterized in that the cylindrical part (28) is monobloc and directly surrounds all the slots of the stator.

6. A distributed winding method for a stator according to any one of claims 1 to 4, characterized in that the cylindrical part (28) comprises a plurality of angular segments (26), and in that the method comprises a step of inserting each angular segment (26) between two teeth of the stator so as to close at least one notch.

7. A distributed winding method of a stator according to claim 6, characterized in that the cylindrical part (28) comprises N angular segments (26), each angular segment (26) being configured for insertion between two teeth of the stator so as to close a notch (16).

8. A distributed winding method for a stator according to any one of claims 1 to 7, characterized in that the central part (12) comprises on the one hand a cylindrical portion (18) comprising N slots (20) distributed over the outer surface of the cylindrical portion, and on the other hand N independent teeth (14), and in that the method comprises a step (120) of manufacturing the central part (12) by inserting each independent tooth into a slot of the cylindrical portion (18).

9. A distributed winding method for a stator according to any one of claims 1 to 8, characterized in that it comprises, following the step of closing the slots, a step (124) of compressing and / or shaping the coil heads according to a predetermined shape.

10. A distributed winding method for a stator according to any one of claims 1 to 9, characterized in that the conductors (32) are Litz wires.

11. Tooling for carrying out a distributed winding method (100) for a stator of an electrical machine, said stator (10) comprising a central star-shaped portion (12) around a shaft comprising at least six teeth (14) separated by gaps forming N notches (16) each intended to receive conductors of a coil associated with a phase of the stator, and a cylindrical part surrounding the central part, characterized in that it comprises a means for simultaneously unwinding N conductors intended to be inserted into the N notches (16), a means for distributing the N conductors (32) so as to arrange each conductor opposite the notch (16) into which a portion of the conductor is to be inserted, a means for inserting each portion of the conductor into said notch, and a means for rotating the stator relative to the tooling for rotating the conductors (32) at the coil heads.

12. Distributed winding stator, characterized in that the distributed winding was made by a distributed winding method (100) according to any one of claims 1 to 10.

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