WO2023285755A1

WO2023285755A1 - Stator for a rotary electrical machine and manufacturing method

Info

Publication number: WO2023285755A1
Application number: PCT/FR2022/051373
Authority: WO
Inventors: Olivier Gas; Nicolas Langlard
Original assignee: Nidec Psa Emotors; Skyazur
Priority date: 2021-07-13
Filing date: 2022-07-08
Publication date: 2023-01-19
Also published as: FR3125365A1

Abstract

The invention relates to a method for manufacturing a stator (1) for a rotary electrical machine, comprising the following steps: (a) providing a set of electrical conductors (10), in particular in the form of a pin, and a plurality of stacks (5) of metal sheets; (b) inserting said electrical conductors into the stacks of metal sheets (5); and (c) twisting the electrical conductors (10), in particular in one or more directions, so as to cause the stacks of metal sheets to be twisted.

Description

Title: Rotating electrical machine stator and manufacturing method

The present invention claims the priority of French application 2107615 filed on July 13, 2021, the content of which (text, drawings and claims) is incorporated herein by reference.

Technical area

The present invention relates to rotating electrical machines and more particularly to the stators of such machines. The invention relates more particularly to the stator mass of the stator and the corresponding rotating electrical machine. It also relates to the method of manufacturing such stators.

The invention relates more particularly to synchronous or asynchronous alternating current machines. It relates in particular to traction or propulsion machines for electric (Battery Electric Vehicle) and/or hybrid (Hybrid Electric Vehicle - Plug-in Hybrid Electric Vehicle) motor vehicles, such as individual cars, vans, trucks or buses. The invention also applies to rotating electrical machines for industrial and/or energy production applications, in particular naval, aeronautical or wind turbine applications.

Prior technique

It is known to provide an angular offset between the laminations of the stator, as for example in patent applications FR 3 067 879, JP 2003 018802, JP 57-183251 and JP 55-053157. We can speak of twisting of the stator.

US patent 10424979 relates to a stator comprising two packs of laminations comprising notches open towards the air gap. The two stacks of sheets are twisted, being separated by a non-electrically conductive central element, comprising a closed yoke and non-twisted straight teeth. In addition, this patent describes a specific insulation system for round wire.

International application WO 2019/142663 relates to a V-twisted stator, in which the electrical conductors are deformed by the stack of laminations. It is therefore necessary to provide for this stator an insulation of electrical conductors of sufficient thickness, which degrades the degree of copper filling of the notches and the thermal resistance. In addition, the stack of stator laminations has an external relief to allow its deformation.

Patent application JP 2020 120536 relates to a non-twisted stator, comprising round wires, and equipped with a cooling fluid distribution plate arranged annularly between two stacks of stator laminations.

There is a need to facilitate the manufacture of twisted stators, and to improve their electromagnetic and cooling performance.

Summary of the invention

Method of manufacturing a stator

The invention aims to meet all or part of this need and thus has as its object, according to one of its aspects, a method for manufacturing a stator for a rotating electrical machine, comprising the following steps:

(a) provide a set of electrical conductors, in particular in the shape of a pin, and a plurality of stacks of sheets,

(b) inserting said electrical conductors into the sheet metal stacks,

(c) twisting the electrical conductors, in particular in one or more directions, to cause twisting of the stacks of sheets.

In the invention, the sheets are stacked aligned, in particular not integral with each other and without angular offset between the sheets, then the stacks of sheets are twisted after insertion of the electrical conductors, which can make it possible to facilitate the insertion of the conductors electrical, which indeed thus takes place in one or more untwisted stacks.

The twisting of the electrical conductors leads to the twisting of the stacks of sheets in which they are inserted. The laminations are forced by the electrical conductors to shift angularly relative to each other around the longitudinal axis X of the stator.

In the invention, the electrical conductors are used to twist the sheets which are only stacked on top of each other without any mechanical effort, which avoids in particular any effort on any insulation of the electrical conductors. In the invention, there is thus advantageously the possibility of using a standard insulator.

Disclosure of Invention

During step (c) of twisting, the twisting of the stacks of sheets can be accompanied from the outside, for example by means of rotary cams supported by twisting plates.

In step (a), the sheets can be stacked on an expanding mandrel.

It is then possible to proceed with the insulation of the bundles of sheets, in particular by inserting the sheets of insulation into notches of the bundles of sheets.

In step (a), you can insert at least one spacer between certain sheets. The spacer thus inserted between the sheets can be intended to separate two stacks of consecutive sheets. The spacer makes it possible to maintain the laminations of the first stack of laminations during this step (e) of twisting of the conductors.

In the case of the presence of a spacer, the sheets of insulation may not be continuous over the entire length of the stator.

Alternatively, it is possible not to insert a spacer, and in this case it is possible to stack the sheets directly on top of each other. In this case, the stacks of sheets may not be separated from each other. They may not be separated from each other by a spacer. In this case, the insulation sheets can be continuous along the entire length of the stator.

The method may include the following additional step:

(a’) insert an insulation device into the stacks of sheets.

The step (a') of inserting the insulation device can take place after the step (a) of supplying, in particular after the step of insulation, and before the step (b) of inserting the conductors electrical.

The method may include the following additional step:

(d) separating the sheets into a plurality of stacks of sheets, in particular into a first stack of sheets and a second stack of sheets.

This step (d) of separation can be carried out by means of the aforementioned extensible mandrel. Step (d) of separation can take place after step (b) of inserting the electrical conductors and before step (c) of twisting.

The method may include the following additional step:

(e) insert between the stacks of sheets a set of twisting tools.

The insertion step (e) can take place after the separation step (d) and before the twisting step (c).

The twisting tools can have the shape of fingers. Each twisting tool can be inserted between two circumferentially consecutive electrical conductors.

The set of twisting tools can comprise a plurality of sets of twisting tools, for example a set at each of the ends of the stator and one or more sets between two stacks of consecutive sheets. Each set may include twisting tools that are circumferentially distributed, in particular regularly distributed.

Step (e) of inserting the twisting tools can take place after step (b) of inserting the electrical conductors, after step (d) of separation and before step (c) of twisting.

The twisting step (c) can be implemented using the aforementioned twisting tools. Twisting tools make it possible to exert circumferential pressure on electrical conductors, in order to deform them to twist them.

Once the twisting of the stacks of sheets has been carried out in step (c), bundles of sheets are obtained.

After twisting the sheets, the twisting tools can be removed. The shape of the stack of laminations observed in a plane containing the longitudinal axis X of the stator on either side of the twisting tools can be that left on the electrical conductors of the winding by the twisting tools. When the twisting tools are rounded in shape so as not to cut into the enamel of the electrical conductors, the shape may be that of a stack in an arc of a circle. The shape could alternatively be straight with rounding in connection with the two end packages.

In an additional step, the bundles of sheets can be clamped axially, then proceed to their welding.

It is then possible to proceed with the inclination of the portions of electrical conductors which protrude axially from the stacks of sheets. Finally, we proceed to the welding of the electrical conductors, to the necessary electrical tests, and to the impregnation of the stator.

The same U-shaped electrical conductor can be placed in two different, non-consecutive slots in the stator mass of the stator. If an electrical conductor is U-shaped, it can be welded to two other electrical conductors on the same side of the machine.

It is possible to interconnect two electrical conductors in the form of an I previously introduced into two different, non-consecutive slots in the stator mass of the stator. In the case where an electrical conductor is I-shaped, it can be welded to another electrical conductor and to the phase connector, on the two opposite sides of the machine.

In the invention, it is possible to electrically connect together all the electrical conductors having a free end located at the same circumferential position around the axis of rotation of the machine, whatever their radial position.

Stator

A further subject of the invention, independently or in combination with the foregoing, is a rotating electrical machine stator manufactured by the process described above.

The invention also relates, independently or in combination with the foregoing, to a stator for a rotating electrical machine, comprising a stator mass formed from a stack of sheets, comprising notches, electrical conductors housed in the notches, in particular at the at least some of the electrical conductors, or even a majority of the electrical conductors, better still all the electrical conductors, being in the shape of a U-shaped or I-shaped hairpin, the stator mass being composed of a plurality of packets arranged consecutively along a longitudinal axis X of the stator, the laminations of at least one package, preferably of all the packages, being angularly offset from each other around the longitudinal axis of the stator, the laminations of the first package being angularly offset in a direction and the laminations of the second package being angularly offset in the other direction, the stator mass being devoid of protuberance on its outer surface. Such a protrusion can be used in the prior art to deform the electrical conductors to twist them through the deformation of the packets carried out by exerting pressure on these protrusions.

On the contrary, in the invention, stacks of sheets and the electrical conductors inserted therein are deformed with the method described above. In the invention, the stacks may have no gripping means. Once the twisting of the stacks of sheets has been carried out, packets of sheets are obtained.

The stator according to the invention makes it possible to improve the noise and vibration reduction performance of the resulting machine, as well as the cooling of the machine.

The invention also makes it possible to reduce the total cost of the machine, by making it possible to simplify the assembly of the rotor with a stack of sheets in a single angular orientation, with an interface between the rotor and a shaft of the simplified machine.

The laminations of the stator lamination stack are magnetic.

The stator mass comprises teeth defining between them the notches, the teeth being attached to a yoke of the stator.

The electrical conductors may have an inclined shape, due to the angular offset between the sheets.

In one embodiment, the electrical conductors have a change in inclination, in particular at the level of the aforementioned spacer or a change of package. They can thus have a double inclination, in one direction then in the opposite direction. The two inclinations can have the same angle in absolute value. At the spacer or a package change, the electrical conductors may have a curvilinear shape. This curvilinear shape may result from the bending of the electrical conductors during the realization of the inclination.

The stator according to the invention may have no weld bead protruding from the outer surface of the stator mass. It may for example be devoid of protuberance on its outer surface. It may have no input means. This can facilitate its insertion into a crankcase. Indeed, the stator is then advantageously devoid of external protrusion which would be restrictive for shrinking in a casing or devoid of grooves in the yoke which would degrade the exchange surface between the stacks and the casing, which is particularly advantageous when the crankcase is water cooled. The stator may however comprise at least one bead of welds of the laminations of the same package.

In order to allow the positioning of the weld bead, the stator may for example comprise on the outer surface of the stator mass one or more lunes or specific shapes allowing welding.

The weld bead may in particular be visible on the outer surface of the stator mass. The weld bead may in particular have an inclination with respect to the longitudinal axis X of the stator, due to the angular offset between the sheets. The inclination of the weld bead(s) can correspond to the value of the angular offset between the sheets. For a given package, the stator may comprise one or more weld beads distributed angularly around the longitudinal axis X of the stator, for example two, three or four. They can in particular be regularly distributed angularly, in particular at 180°, or at 120°, or even at 90°.

The weld beads can be continuous over the length of a packet, or even all the packets, or alternatively interrupted at the level of the possible spacer.

The weld beads can advantageously be continuous over the length of all the packages, in particular when the spacer comprises metallic elements. Indeed, these metal elements allow the weld beads to extend from the first pack of sheets to the metal elements of the spacer and then to the second pack of sheets. This solution considerably improves the mechanical integrity of the stator before insertion into a casing or a firette.

Two consecutive packets can be directly attached to each other. In the invention, the stator may have no spacer between two consecutive packages. The stacks of sheets may not be separated from each other. They may not be separated from each other by a spacer.

As a variant, two consecutive packets can be separated by a spacer.

The spacer can be magnetic. It may comprise a magnetic material.

As a variant, the spacer separating the stacks of laminations can be non-magnetic. It may comprise a non-magnetic material. At the level of the non-magnetic spacer, there is therefore no circulation of magnetic flux.

The spacer can be at least partially metallic, or even entirely metallic. The metal used can be magnetic or non-magnetic. As a variant or additionally, the spacer can be at least partially made of a non-metallic material, for example plastic.

The spacer may in one embodiment comprise a ring of plastic material, for example molded onto metal elements, for example of parallelepiped shape. These metal elements can have a mechanical role while the plastic used for the overmolding can facilitate the passage of the cooling fluid or integrate a thermal probe.

The spacer may include cylinder head plates. The spacer cylinder head laminations can be magnetic or non-magnetic. They comprise a so-called yoke annular part, which is superimposed on a yoke of the stator mass. In particular, they may be devoid of teeth. The spacer may have teeth. The teeth of the spacer can be superimposed on a yoke of the stator mass. The teeth of the spacer can be inclined with respect to the longitudinal axis of the stator, or not be inclined. The teeth of the spacer can be placed radially in line with the notches of the stator mass.

The spacer may advantageously include teeth, in particular when there is continuity of the slot insulation between two stacks of laminations of the stator mass.

The spacer teeth can span the yoke width of the stator when aligned with the slots in the stator, improving the thermal performance of the machine. Alternatively, the spacer teeth may cover the yoke width of the stator as well as a portion of the corresponding stator tooth, when aligned with the stator teeth formed between the notches thereof, thereby improves the mechanical performance of the machine.

The spacer may comprise a cylinder head part connecting the teeth of the spacer to each other. This yoke part can be superimposed with a yoke of the stator mass.

The spacer may include a cylinder head part providing openings to the outside. Said openings can be made between the teeth mentioned above. The openings of the spacer can be placed radially in line with the teeth of the stator mass.

The spacer can make it possible to constitute a fresh air inlet in the center of the machine, to favor the circulation of air in the stator, and thus to improve the machine cooling. This is particularly useful on a long machine. A stator according to the invention can also be useful on a machine comprising a water-cooled casing.

The spacer according to the invention can make it possible to improve the cooling of the machine by creating a channel for the passage or supply of a cooling fluid, liquid or gaseous, such as air, oil or other.

Thanks to the invention, it is possible to benefit from a cooling circuit passing through the heart of the stator thanks to the assembly of the stator and the casing.

In one embodiment, the rotor mass may comprise one or more vents for the passage of a cooling fluid, corresponding to openings in the spacer of the stator, to allow the flow of the cooling fluid. This can then flow through ducts formed by the assembly of the housing and the stator.

The spacer may have a height measured along the longitudinal axis of the stator of between 1 and 10 mm, better still between 2 and 8 mm, or even between 3 and 6 mm.

The spacer may in particular have a height measured along the longitudinal axis of the stator of between one and three times the height of the slot insulators, being in particular approximately twice the height of the slot insulators projecting from the package, otherwise called overhang of the package insulators. 'Height of the notch insulators' means the height of the insulators which protrude from the notches of the stack of sheets. Such a height makes it possible to reduce the risks of short-circuit at the level of the interface between the consecutive packets, and to increase the arcing distance, in particular between the conductor and the mass.

Each plate can be offset from the adjacent plate by an elementary angle. In the same stack of plates, the elementary angle can be constant. Between two stacks of sheets, the elementary angle can be the same in absolute value. As a variant, the elementary angle may be different from one stack of sheets to another.

The elementary angle of the angular offset between two consecutive sheets can be between 0.004° and 0.085°, being for example between 0.017° and 0.032°, better still between 0.008 and 0.016°, being for example of the order of 0.01 °.

A total angular offset of a stack of sheets, measured between a first sheet and a last sheet of the stack of sheets, can be between 2 and 10°, being for example between 2.5 and 8°, better still between 3 and 6°, being for example of the order of 3.75°. The elementary angle of the angular offset between two consecutive laminations may correspond to the tooth pitch of the stator over the height of the package divided by the number of laminations in the package. In one embodiment, the elementary angle is equal to the tooth pitch divided by the number of sheets in the stack.

The sum of the elementary angles of the packets can preferably be zero, in order to avoid an axial component. The angle chosen for the angular offset of a single packet can be identical to that used for the different packets in the case of V or W offset packets.

Sheets in the same stack can be offset relative to each other by a constant elementary angle. In one embodiment, all the laminations of each stack of the stator can be offset relative to each other by a constant elementary angle.

The sheets of the same package can be offset from each other by a variable elementary angle, with for example a curvilinear variation.

The stator mass may in one embodiment comprise two packets. As a variant, it may comprise more than two packets, in particular three or four or more. The stator mass may comprise an even number of packets. As a variant, the stator mass can comprise an odd number of packets.

The laminations of the stator mass packages can all be angularly offset in the same direction around the longitudinal axis X of the stator.

As a variant, the laminations of the stator mass packages can be angularly offset in at least two directions, in particular in several directions, around the longitudinal axis X of the stator.

The laminations of the stator mass packages can be angularly offset successively in one direction then in the other, being arranged in a V. They can be arranged in a V, being offset symmetrically with respect to a plane of symmetry perpendicular to the longitudinal axis X of the stator. The V arrangement, with a twist in two different directions, makes it possible to minimize or even eliminate the load exerted on the bearings of the rotor.

The stator mass may comprise a single central package cut in two by said plane of symmetry. As a variant, the stator mass can comprise two central packets separated by said plane of symmetry. The two central packets may not be angularly offset relative to each other.

In one embodiment, the stator may comprise two packs of laminations, a first pack of laminations offset angularly in one direction, and a second pack of laminations offset angularly in the other direction. The elementary offset angles can have the same absolute value. This can advantageously make it possible to completely cancel the axial component of the torque on the rotor.

In one embodiment, the laminations of the stator mass packages can be angularly offset successively in one direction then in the other, being arranged in a herringbone pattern. Advantageously, the chevrons are arranged symmetrically.

All of the stator packages may each have the same length, or alternatively different lengths.

Two packets can have different lengths. For example, the arrangement of the bundles in the stator mass may be such that the length of the bundles may increase and then decrease as one moves along the axis of the stator, or increase all the way along the stator, or decrease all the way. along the stator.

In combination with the above, the sum of the angular offset angles of the packets can be zero.

Alternatively again, the length of the bundles may vary with a sawtooth variation as one moves along the axis of the stator.

In one embodiment, the central packet or packets may have a different length from the other packets, for example a shorter or longer length.

The slots in the stator can be closed. By “closed notch”, is meant notches which are not open radially towards the air gap.

In one embodiment, at least one notch, or even each notch, can be continuously closed on the air gap side by a bridge of material coming in one piece with the teeth defining the notch. All the notches can be closed on the air gap side by bridges of material closing the notches. The material bridges may be integral with the teeth defining the notch. The stator mass then has no cutout between the teeth and the bridges of material closing the slots, and the notches are then continuously closed on the side of the air gap by the bridges of material coming from a single piece with the teeth defining the notch.

In addition, the notches can also be closed on the side opposite the air gap by a yoke in one piece with the teeth or added. The notches are then not open radially outwards. The stator mass may have no cutout between the teeth and the yoke.

In one embodiment, each of the notches has a continuously closed contour. By “continuously closed” is meant that the notches have a continuous closed contour when viewed in cross section, taken perpendicular to the axis of rotation of the machine. You can go all the way around the notch without encountering a cutout in the stator mass.

The stator mass can be made by stacking magnetic laminations, the notches being made by cutting the laminations. The closing of the slots on the side of the air gap is obtained by bridges of material coming from a single piece with the rest of the laminations forming the stator mass.

The stator may be devoid of added magnetic shims for closing the slots. This eliminates the risk of accidental detachment of these wedges.

In the stator according to the invention, at least some of the electrical conductors, or even a majority of the electrical conductors, better still all the electrical conductors, can be in the shape of a U- or I-shaped hairpin.

The stator may include two electrical conductors per slot. The stator may in one embodiment comprise two columns of electrical conductor strands.

The electrical conductors can form a distributed winding. The winding can be corrugated or interleaved. The winding may not be concentrated or tooth wound. Electrical conductors can form a whole or fractional winding.

Each electrical conductor may comprise one or more strands (“wire” or “strand” in English). By "strand" is meant the most basic unit for electrical conduction. A strand can be of round cross section, we can then speak of 'thread', or flat. The flat strands can be shaped into pins, for example U or I. Each strand is coated with an insulating enamel. The electrical conductors can form a single winding, in particular whole or fractional. By "single winding", it is meant that the electrical conductors are electrically connected together in the stator, and that the connections between the phases are made in the stator, and not outside the stator, for example in a terminal box. . A winding is made up of a number of phases m staggered in space in such a way that when they are supplied by a multi-phase current system, they produce a rotating field.

The winding can be whole or fractional in the invention. The winding can be full-pitch with or without shortening, or in a fractional variant. In one embodiment, the electrical conductors form a fractional winding, in particular with a shortened pitch.

For a fractional winding, the number of notches per pole and per phase is fractional, i.e. the ratio q defined by Z=Ns/(2/¾/) is written in the form of a irreducible fraction zhn, z and m being two non-null integers, m being different from 1, where Ns is the number of notches of the stator, q the number of phases of the winding and p the number of pairs of poles.

The number of notches of the stator can be between 18 and 96, better still between 30 and 84, being for example 18, 24, 27, 30, 36, 42, 45, 48, 54, 60, 63, 72, 81 , 92, 96, better being 48 or 60 or 63. The number of poles of the stator can be between 2 and 24, or even between 4 and 12, being for example 6 or 8.

The combination number of notches/number of poles of the stator can be chosen from the combinations of the following list, which is not exhaustive: 30/4, 42/4, 45/6, 48/8, 63/6, 60/8, 84/8.

At least one first electrical conductor housed in a first notch can be electrically connected to a second electric conductor housed in a second notch, at the exit from said notches.

All electrical conductors having a free end located at the same circumferential position around the axis of rotation of the machine, whatever their radial position, can be electrically connected together.

The stator may comprise a phase connector comprising metallic elements connected to electrical conductors of the stator. The metal elements can be arranged radially externally or internally with respect to the electrical conductors to which they are connected. The metal elements connected to conductors of the stator windings can be held by an insulating support. Furthermore, the phase connector may have lugs for connection to a power supply bus. The machine can thus be connected to an inverter, electrically connected to the connection tabs of the connector.

Pins

Electrical conductors at least, see a majority of electrical conductors, can be pin-shaped, U-shaped or I-shaped. The pin can be U-shaped ("U-pin" in English) or straight, being in form of I ("I-pin" in English).

The hairpin and flat electrical conductors increase the filling factor of the slot, making the machine more compact. Thanks to a high filling coefficient, heat exchanges between the electrical conductors and the stator mass are improved, which makes it possible to reduce the temperature of the electrical conductors inside the slots.

Furthermore, the manufacture of the stator can be facilitated thanks to the electrical conductors in the form of pins. Finally, the pins do not require having open notches, we can have closed notches which allow the pins to be held and we can therefore eliminate the step of inserting the stator wedges.

Electrical conductors, or even a majority of the electrical conductors, extend axially in the slots. The electrical conductors can be introduced into the corresponding slots by one or both axial ends of the machine.

An I-shaped electrical conductor has two axial ends each placed at one of the axial ends of the stator. It passes through a single notch, and can be welded at each of its axial ends to two other electrical conductors, at the axial ends of the stator. The stator may for example comprise 6, 10, 12, 14, 18, 22 or 26 I-shaped electrical conductors, the other electrical conductors all being able to be U-shaped.

The stator may be devoid of an I-shaped electrical conductor.

A U-shaped electrical conductor has two axial ends both placed at one of the axial ends of the stator. These two axial ends are defined by the two legs of the U. It passes through two different notches, and can be welded at each of its axial ends to two other electrical conductors, at the level of a same axial side of the stator. The bottom of the U, that is to say the side of the U forming the bun or coil head, is arranged on the other axial side of the stator.

At least a portion of the electrical conductors, or even a majority of the electrical conductors, may be U-shaped hairpin.

In addition, the size of the electrical conductors at the level of the coil heads is reduced. This facilitates the interweaving of electrical conductors.

Strands

In the invention, each electrical conductor may comprise one or more strands (“wire” or “strand” in English). By “strand” we mean the most basic unit for electrical conduction. A strand can be of round cross section, we can then speak of a 'thread', or flat. The flat strands can be shaped into pins, for example U or I. Each strand is coated with an insulating enamel.

The fact that each notch can comprise several conductors and/or several strands makes it possible to minimize the losses by induced currents, or AC Joule losses, which evolve with the square of the supply frequency, which is particularly advantageous at high frequency and when the running speed is high. Heat transfer to the cold source is also facilitated. It is thus possible to obtain better performance at high speed.

When the notches are closed, it is possible to obtain a reduction in the leakage flux seen by the conductors, which leads to a reduction in the losses by Joule effect.

In one embodiment, each electrical conductor may comprise several pins, each forming a strand, as explained above. All the strands of the same electrical conductor can be electrically connected to each other at the exit from the notch. The strands electrically connected to each other are placed in short circuit. The number of strands electrically connected together can be greater than or equal to 2, being for example between 2 and 12, being for example 3, 4, 6 or 8 strands.

Several strands can form the same electrical conductor. The same electric current of the same phase circulates in all the strands of the same electrical conductor. All the strands of the same electrical conductor can be electrically connected to each other, in particular at the exit from the notch. All the strands of the same electrical conductor can be electrically connected to each other at each of their two axial ends, in particular at the exit from the notch. They can be electrically connected in parallel.

All the strands of all the electrical conductors having a free end located at the same circumferential position around the axis of rotation of the machine, whatever their radial position, can be electrically connected to each other.

In one embodiment, each electrical conductor has three strands. In the case where a notch comprises two electrical conductors, a notch can therefore house six strands, for example, distributed between the two electrical conductors.

Alternatively, a slot has four electrical conductors. Each electrical conductor may comprise two strands. The notch then houses eight strands, distributed between the four electrical conductors.

The strands of the same electrical conductor can be in contact two by two over their entire length. They may in particular be in contact at the level of the coil heads. In addition, they may in particular be in contact at the weld ends. They can be joined. In one embodiment, the strands can be welded in pairs of three strands. Such a configuration allows good optimization of the space available in and around the stator. We gain in particular in compactness at the level of the height of the buns. In addition, the risks of short-circuiting between the electrical conductors can be reduced.

The strands can be positioned in the notch so that their circumferential dimension around the axis of rotation of the machine is greater than their radial dimension. Such a configuration allows a reduction in losses by eddy currents in the strands.

A strand can have a width of between 1 and 5 mm, being for example of the order of 2.65 or 3 mm. The width of a strand is defined as its dimension in the circumferential direction around the axis of rotation of the machine.

A strand can have a height comprised between 1 and 5 mm, being for example of the order of 1.25 or 1.8 mm. The height of a strand is defined as its thickness in the radial dimension.

The electrical conductors can be made of copper or aluminum, or any other enamelled conductive material or coated with any other suitable insulating coating. The stator mass can be produced by stacking sheets. The teeth can be interconnected by material bridges, and on the opposite side by a yoke. The notches can be closed. They can be produced entirely by cutting in the sheets. Each sheet of the stack of sheets can be monobloc.

Each sheet is for example cut from a sheet of magnetic steel or sheet containing magnetic steel, for example steel 0.1 to 1.5 mm thick. The sheets can be coated with an electrically insulating varnish on their opposite faces before they are assembled within the stack. Electrical insulation can still be obtained by heat treatment of the sheets, if necessary.

The stator may include an outer carcass surrounding the yoke.

The stator teeth can be made with a stack of magnetic laminations, each covered with an insulating varnish, in order to limit the losses by induced currents.

Machine

Another subject of the invention, according to another of its aspects, independently or in combination with the foregoing, is a rotating electrical machine comprising a stator as defined above.

The rotating electrical machine can be synchronous or asynchronous. The machine can be used as a motor or as a generator. The machine can be reluctance. It can constitute a synchronous motor or, as a variant, a synchronous generator. As a further variant, it constitutes an asynchronous machine.

The maximum speed of rotation of the machine can be high, being for example greater than 10,000 rpm, better still greater than 12,000 rpm, being for example of the order of 14,000 rpm to 15,000 rpm. min, or even 20,000 rpm or 24,000 rpm or 25,000 rpm. The maximum speed of rotation of the machine may be less than 100,000 rpm, or even 60,000 rpm, or even even less than 40,000 rpm, better still less than 30,000 rpm.

The invention may be particularly suitable for high-powered machines.

Rotor

The rotating electrical machine may include a rotor. The rotor may include a rotor mass. The rotor can be permanent magnets, with surface or buried magnets. The rotor can be flux concentrating. It may include one or more layers of magnets arranged in an I, U or V. Alternatively, it may be a wound or squirrel cage rotor, or a variable reluctance rotor.

The rotor mass can extend along the axis of rotation and arranged around a shaft. The shaft may include torque transmission means for driving the rotor mass in rotation.

The rotor may include permanent magnets inserted into the rotor mass. The rotor mass may comprise rotor laminations. The housings for the permanent magnets can be produced entirely by cutting in the sheets. Each sheet of the stack of sheets can be monobloc.

Alternatively, it may be a wound or squirrel cage rotor, or a variable reluctance rotor.

The rotor can be provided with a vent aligned axially with the spacer of the stator, which can advantageously make it possible to constitute a circulation of a cooling fluid in the machine.

The number of pairs of poles p at the rotor is for example between 1 and 24, being for example 1, 2, 3, 4, 5 or 6.

The diameter of the rotor may be less than 600 mm, or even less than 400 mm, better still less than 300 mm, better still less than 200 mm, and greater than 40 mm, better greater than 60 mm, being for example between 80 and 160 mm.

The shaft can be made of a magnetic material, which advantageously makes it possible to reduce the risk of saturation in the rotor mass and to improve the electromagnetic performance of the rotor.

As a variant, the rotor comprises a non-magnetic shaft on which the rotor mass is arranged. The shaft can be made at least in part from a material from the following list, which is not exhaustive: steel, stainless steel, titanium or any other non-magnetic material.

The rotor mass can in one embodiment be placed directly on the non-magnetic shaft, for example without an intermediate rim. As a variant, in particular in the case where the shaft is not non-magnetic, the rotor may comprise a rim surrounding the shaft of the rotor and coming to rest on the latter. The rotor mass may comprise one or more holes to lighten the rotor, to allow its balancing or for the assembly of the rotor plates constituting it. Holes can allow passage of the tie rods now integral with the sheets.

Sheets can be cut in a tool one after the other. They can be stacked and clipped or glued into the tool, in complete bundles or sub-bundles. The sheets can be clicked on top of each other. Alternatively, the stack of sheets can be stacked and welded outside the tool.

The rotor mass may have an outer contour which is circular or multi-lobed, a multi-lobed shape being useful for example to reduce torque ripples or current or voltage harmonics.

The rotor may comprise at least one flange which may be arranged at one end of the pack of rotor laminations. In one embodiment, the rotor comprises two flanges each disposed at one end of the pack of rotor laminations.

In one embodiment, the rotor is not twisted, being straight.

The rotor can be cantilevered or cantilevered from the bearings used to guide the shaft.

The machine may comprise a single inner rotor or, as a variant, an inner rotor and an outer rotor, arranged radially on either side of the stator and coupled in rotation.

The machine can be inserted alone into a casing or inserted into a gearbox casing. In this case, it is inserted into a casing which also houses a gearbox.

Brief description of the drawings

The invention can be better understood on reading the detailed description which follows, of a non-limiting example of embodiment thereof, and on examining the appended drawing, in which: [Fig 1] Figure 1 is a perspective view, schematic and partial, of a stator according to the invention.

[Fig 2] Figure 2 is a perspective view, schematic and partial, of the stator of Figure 1 during manufacture.

[Fig 3] Figure 3 is a perspective view, schematic and partial, of the stator of Figure 1 during manufacture.

[Fig 4] Figure 4 is a perspective view, schematic and partial, of the stator of Figure 1 during manufacture.

[Fig 5] Figure 5 is a perspective view, schematic and partial, of the stator of Figure 1 during manufacture.

[Fig 6] Figure 6 is a perspective view, schematic and partial, of the stator of Figure 1 during manufacture.

[Fig 7] Figure 7 is a perspective view, schematic and partial, of the stator of Figure 1 during manufacture.

[Fig 8] Figure 8 is a perspective view, schematic and partial, of the stator of Figure 1 during manufacture.

[Fig 9] Figure 9 is a perspective view, schematic and partial, of the stator of Figure 1 during manufacture.

[Fig 10] Figure 10 is a perspective view, schematic and partial, of the stator of Figure 1 during manufacture.

[Fig 11] Figure 11 is a perspective view, schematic and partial, of the stator of Figure 1 during manufacture.

detailed description

There is illustrated in Figure 1 a stator 1 of a rotating electrical machine, comprising a stator mass 2 comprising notches 3 and teeth 4 defining between them the notches, the teeth being attached to a yoke 57. The notches of the stator are closed.

The stator 1 comprises a winding comprising electrical conductors 10 housed in the notches 3. In the example described, the stator comprises two electrical conductors 10 per notch.

The electrical conductors 10 are generally rectangular in cross section, with rounded corners. They are in the example described superimposed radially in a single row. The circumferential dimension of an electrical conductor corresponds substantially to the width of a notch.

The electrical conductors 10 are made of copper or aluminum, or any other enamelled conductive material or coated with any other suitable insulating coating.

The electrical conductors 10 are in the shape of a U-shaped hairpin. They each comprise first and second legs intended to extend axially respectively in first and second notches of the stator.

The stator mass 2 is formed from a stack of magnetic laminations, and is composed of two packets 5 arranged consecutively along a longitudinal axis X of the stator. The two packets 5 each have the same length.

The laminations of the packages are angularly offset from each other around the longitudinal axis of the stator, as shown in figure 1.

Each sheet is offset from the adjacent sheet by an elementary angle. In the same stack of plates, the elementary angle is constant. The elementary angle of the angular offset between two consecutive sheets can be in the example described of the order of 0.01°. Its value can vary from 0° excluded to a value equal to the tooth pitch.

The sheets of the packages 5 of the stator mass 2 are angularly offset successively in one direction then in the other, being arranged in a V, the sheets of the first package being angularly offset in one direction and the sheets of the second package being angularly offset in the 'other way. The V arrangement, with a twist in two different directions, makes it possible to minimize or even eliminate the load exerted on the bearings of the rotor.

In addition, it can be noted that the two consecutive packets 5 are directly attached to each other. The stator shown does not have a spacer between two consecutive packages.

As can be seen in FIG. 1, the stator mass has no protuberance on its outer surface, and in particular no weld bead on the outer surface of the stator mass.

The stator comprises oblique ribs 30 which serve to accompany the sheets during the twisting of the stack of sheets, then locations for the production of the weld seams of the sheets of the same package 5, which can be visible on the surface exterior of the stator mass 2, once the packages 5 have been welded, but without protruding from the outer surface of the stator mass. The resulting weld beads have an inclination with respect to the longitudinal axis X of the stator, due to the angular offset between the sheets. This inclination corresponds to that of the angular offset between the sheets.

We will now describe the method of manufacturing the stator of Figure 1, with reference to Figures 2 to 11.

In a first step (a) of the process, a set 9 of electrical conductors 10 in the form of a pin and a plurality of stacks of sheets 5 are provided. At this stage of the process, the stacks of sheets can be combined into a set sheets, as shown in Figure 2.

In step (a), the sheets can be stacked on an expanding mandrel, directly on top of each other. In this case, the stacks of sheets may not be separated from each other. They may in particular not be separated from each other by a spacer.

It is then possible to proceed with the insulation of the stacks of sheets in step (a′) by inserting into the stacks of sheets an insulation device 12 visible in isolation in FIG. 2, namely by inserting into the notches of the stacks of sheets of the insulating sheets, as illustrated in Figure 3. Also seen in Figure 3 is the assembly 9 of electrical conductors 10.

Step (a′) of inserting the insulation device 12 can take place after step (a) of supplying, and before step (b) of inserting the electrical conductors described below.

We then proceed to step (b) of inserting said electrical conductors into the stacks of sheet metal, as illustrated in Figure 4.

The method may include the following additional step:

(d) separating the sheets into a first stack of sheets and a second stack of sheets, as shown in Figure 5.

This step (d) of separation can be carried out by means of the aforementioned extensible mandrel.

Step (d) of separation can take place after step (b) of inserting the electrical conductors and before step (c) of twisting. The method may include the following additional step:

(e) insert between the stacks of sheets a set of twisting tools 20, as shown in Figure 6.

The twisting tools can have the shape of fingers. Each twisting tool 20 can be inserted between two circumferentially consecutive electrical conductors, as illustrated in FIG. 7. FIG. 7 shows the twisting tools 20 fully inserted between the stacks of sheets.

The set of twisting tools 20 may comprise a plurality of sets of twisting tools, for example a set at each of the ends of the stator and one or more sets between two stacks of consecutive sheets. Each set may comprise twisting tools 20 circumferentially distributed.

In step (c) illustrated in FIG. 8, the electrical conductors are twisted, in particular in two directions, to cause the twisting of the stacks of sheets, by means of the aforementioned twisting tools 20. The twisting tools make it possible to exert circumferential pressure on the electrical conductors 10, in order to deform them to twist them.

In the invention, the stacks of sheets are twisted after insertion of the electrical conductors. The twisting of the electrical conductors leads to the twisting of the stacks of sheets in which they are inserted. The laminations are forced by the electrical conductors to shift angularly relative to each other around the longitudinal axis X of the stator, and the stator shown in Figure 9 is obtained.

In the illustrated embodiment, the electrical conductors thus exhibit a change in inclination. They thus have a double inclination, in one direction then in the opposite direction. The two inclinations have in this example the same angle in absolute value.

In an additional step, the bundles of sheets are clamped axially, as illustrated in FIG. 10, then they are welded from the outside. We then set up a weld bead on the sheets of the same package in the aforementioned oblique ribs 30, not projecting outwards.

One can then proceed with the inclination of the portions of electrical conductors which protrude axially from the laminations, as illustrated in figure 11. Finally, one proceeds to the welding of the electrical conductors, to the necessary electrical tests, and to the impregnation of the stator .

With regard to welding, one can place the same U-shaped electrical conductor in two different non-consecutive notches of the stator mass of the stator. If an electrical conductor is U-shaped, it can be welded to two other electrical conductors on the same side of the machine.

Claims

1. Method for manufacturing a stator (1) of a rotating electrical machine, comprising the following steps:

(a) providing a set of electrical conductors (10), in particular in the shape of a pin, and a plurality of stacks (5) of sheets,

(b) inserting said electrical conductors into the sheet metal stacks (5),

(c) twisting the electrical conductors (10), in particular in one or more directions, to cause the twisting of the stacks of sheets.

2. Method according to the preceding claim, wherein in step (a) at least one spacer is inserted between certain sheets.

3. Method according to one of the two preceding claims, comprising the following additional step:

(a’) insert an insulation device (12) into the stacks of sheets.

4. Method according to any one of the preceding claims, comprising the following additional step:

(d) separating the sheets into a plurality of stacks of sheets (5), in particular into a first stack of sheets and a second stack of sheets.

5. Method according to any one of the preceding claims, comprising the following additional step:

(e) inserting between the stacks of sheets (5) a set of twisting tools (20).

6. Stator (1) of a rotating electrical machine, comprising a stator mass (2) formed of a stack of sheets, comprising notches (3), electrical conductors (10) housed in the notches, at least some of the conductors electric being in the shape of a hairpin in U or in I, the stator mass (3) being composed of a plurality of packets (5) arranged consecutively along a longitudinal axis (X) of the stator, the sheets of at least least one first packet and one second packet, better of all the packets, being angularly offset from each other around the longitudinal axis (X) of the stator, the laminations of the first packet being angularly offset in one direction and the laminations of the second stack being angularly offset in the other direction, the stator mass (3) being devoid of protuberance on its outer surface.

7. Stator according to the preceding claim, being devoid of weld bead protruding from the outer surface of the stator mass.

8. Stator according to one of the two preceding claims, two consecutive packets (5) being directly joined to one another.

9. Stator according to one of the three preceding claims, two consecutive packets (5) being separated by a spacer (20).

10. Stator according to one of the four preceding claims, the laminations of the same package (5) being offset relative to each other by a constant elementary angle.

11. Stator according to any one of claims 6 to 10, the plates of the packages (5) of the stator mass (2) being angularly offset successively in one direction then in the other, being arranged in herringbone pattern.

12. Stator according to any one of claims 6 to 11, a majority of the electrical conductors, better all the electrical conductors, being in the shape of a U or I hairpin.

13. Stator according to any one of claims 6 to 12, all the packages (5) of the stator (1) each having the same length.

14. Stator (1) of a rotating electrical machine, comprising a stator mass (2) formed from a stack of sheets, comprising closed notches (3), electrical conductors (10) housed in the notches, in particular at least a part electrical conductors being in the shape of a U-shaped or I-shaped hairpin, the stator mass (3) being composed of a plurality of packets (5) arranged consecutively along a longitudinal axis (X) of the stator, the laminations at least a first packet and a second packet, better of all the packets, being angularly offset from each other around the longitudinal axis (X) of the stator, the laminations of the first packet being angularly offset in one direction and the laminations of the second stack being angularly offset in the other direction, the stator mass (3) being devoid of any protuberance on its outer surface.

15. Rotary electrical machine (1) comprising a stator (2) according to any one of claims 6 to 14 and a rotor.