EP3931940A1

EP3931940A1 - Stator for a rotating electrical machine

Info

Publication number: EP3931940A1
Application number: EP20719671.8A
Authority: EP
Inventors: Tahar HAMITI; Lamya BELHAJ; Xavier JANNOT; Jacques Saint-Michel
Original assignee: Nidec PSA Emotors SAS
Current assignee: Nidec PSA Emotors SAS
Priority date: 2019-02-28
Filing date: 2020-02-26
Publication date: 2022-01-05
Also published as: FR3093385A1; WO2020174187A1

Abstract

Disclosed is a stator for a rotating electrical machine, comprising a stator mass (25) that has slots (21), electrical conductors being housed in the slots, at least some of the electrical conductors, or even a majority of the electrical conductors, being pin-shaped, in particular U-shaped or I-shaped, and extending axially in the slots, at least one first electrical conductor housed in a first slot being electrically connected to a second electrical conductor housed in a second slot, at the outlet of said slots, each of the slots having an uninterruptedly closed contour.

Description

Title: Rotating electric machine stator

The present invention claims the priority of the French application 1902063 filed on February 28, 2019, the content of which (text, drawings and claims) is incorporated here by reference.

The present invention relates to rotating electrical machines and more particularly to the stators of such machines.

Technical area

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

Prior art

In known stators, the stator yoke has fully open or semi-open notches in the direction of the air gap, so as to allow the introduction of the conductors of the windings. Generally, the semi-open slots receive electrical conductors of circular cross section arranged in bulk, while the fully open slots accommodate electrical conductors of rectangular cross section, arranged in a row.

Stators are known in which the notches are closed by non-magnetic or semi-magnetic wedges. However, such wedges may come loose and interfere with the operation of the machine.

In US Pat. No. 7,348,705, the notches are semi-closed, and house U-shaped electrical conductors, the electrical conductors being distributed between two sets of independent coils over four layers, two layers per set of coils. The conductors of two different coil sets are not electrically connected together in the stator. The connections between the phases are made outside the stator, in a terminal box. The patent application US 2010/001609 relates to a stator in which the slots are closed, and receive U-shaped electrical conductors of rectangular section, which are each connected to a conductor of the adjacent slot, in order to form a series winding corrugated. The winding is not fractional.

Patent application FR 3,019,947 describes a stator comprising a toothed ring comprising teeth interconnected by bridges of material and defining between them recesses for receiving the coils, the notches being open radially outwards. The openings of the notches are closed by a cylinder head attached to the serrated crown.

There is a need to benefit from an easy-to-assemble rotating electric machine stator allowing efficient filling of the slots, while ensuring satisfactory electromagnetic performance. There is also a need to further improve the stators of electric machines and in particular to reduce torque ripples, electromagnetic vibrations and noise.

Disclosure of the invention

Stator

The invention aims to meet this need and it achieves it, according to one of its aspects, thanks to a stator of a rotating electric machine, comprising a stator mass comprising notches, electrical conductors being housed in the notches, at least. some of the electrical conductors, or even a majority of the electrical conductors, being in the shape of a pin, in particular a U or I, and extending axially in the notches, each of the notches having a continuously closed contour.

By "continuously closed" it 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 closed notches are thus not open radially outwards.

The presence of these closed notches makes it possible to improve the performance of the electric machine in terms of the quality of the magnetic field in the air gap, by minimizing the harmonic content and the losses by eddy currents in the electrical conductors, and the leakage fluxes. in the notches, as well as fluctuations in the magnetic field in the air gap. In addition, the presence of these closed notches makes it possible to improve the mechanical rigidity of the stator, by mechanically strengthening the stator and reducing vibrations. In particular, it is possible to obtain a separation of the resonance frequencies from the deformation mode corresponding to 2p, p being the number of pairs of poles of the stator. Reducing vibrations can help make machine operation quieter.

Also, closing the notch can reduce the parasitic capacitance between the stator windings and the rotor, which reduces leakage currents and can eliminate the need for drain rings or brushes. tree currents.

The stator mass can be produced by stacking magnetic sheets, the notches being formed by cutting the sheets. The stator mass can also be by cutting from a mass of sintered or agglomerated magnetic powder. The closing of the notches on the side of the air gap is obtained by bridges of material formed in one piece with the rest of the sheets or the block forming the stator mass.

The stator according to the invention does not have any attached magnetic wedges for closing the notches. This eliminates the risk of accidental detachment of these wedges.

The stator mass may include teeth formed between the notches (21), which are interconnected on the side of the air gap by bridges of material. The material bridges define a bottom of the notches on the air gap side. The bottom of the notches on the air gap side can be connected to the radial edges of the notches by rounded edges. These roundings can help to create a progressive magnetic saturation of the corresponding material bridge.

The bridges of material may have at least one localized constriction formed by at least one groove. The groove (s) may be centered relative to the slot (s). Thanks to this centered groove, it is not necessarily necessary to seek to further reduce the torque ripples. In addition, it improves cooling. Indeed, the groove can make it possible to facilitate the passage of a cooling fluid. The cooling fluid can advantageously circulate in the corresponding notch in a centered manner, which makes it possible to improve the distribution of the cooling. The cooling fluid can be a gas, for example air, or a liquid, for example water or oil. The centering of the groove can also allow the use of symmetrical sheets, which can be placed in one direction or the other. Moreover, in the event of impregnation of the stator, the presence of the groove and even better its possible centering can make it possible to facilitate the circulation of the impregnation varnish.

The groove or grooves may each be of curved profile in section in a plane perpendicular to the axis of the stator, being for example of substantially semi-circular section, in the form of an arc of a circle, or semi-elliptical or wavy. Such a shape of the grooves can allow a gradual saturation of the corresponding material bridge, which is better than with sharp angles.

The smallest width of the bridges of material may be between 0.2 and 0.5 mm. The width of a bridge is advantageously very small, in order to promote the arrival of magnetic saturation of the material bridge. However, it cannot be too low in order to guarantee sufficient mechanical strength of the corresponding sheet. In one embodiment, the thickness of the material bridge may for example be substantially equal to at least the thickness of the corresponding sheet. For example, the width of the bridge may be between 1 and 2 times the thickness of the sheet, even between 1 and 1.6 times the thickness of the sheet, better still between 1 and 1.5 times the thickness of the sheet metal.

Each of the notches may have a continuously closed contour. At least one notch may have radial edges having one or more ribs. The presence of the rib on a radial edge of a notch can allow better control of the minimum distance between two electrical conductors present in the notch. The electrical conductor on the cylinder head side is better maintained in position. It is thus possible to keep a well-controlled minimum insulation distance between the two electrical conductors, and possibly to pass a cooling fluid. This gives better insulation between the electrical conductors. Furthermore, the space thus created between the two electrical conductors can make it possible to facilitate the circulation of a cooling fluid between these two electrical conductors, which can help to promote their cooling as well as that of the stator mass. For example, it is thus possible to have a channel in the center of the notch, between the two electrical conductors, in which a cooling fluid can circulate which can be a gas, for example air, or a liquid, for example air. 'water or oil.

Moreover, in the event of impregnation of the stator, the presence of the rib can make it possible to facilitate the circulation of the impregnation varnish between the conductors. electrical, which can ensure better dielectric strength and better service life.

Electric conductors

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

The term “electrically connected” includes any type of electrical connection, in particular by welding, with different possible welding methods, in particular laser, induction, friction, vibrations, ultrasound or brazing, or by mechanical clamping, in particular by crimping, screwing or riveting. for example.

The first and second notches are preferably non-consecutive.

The first and second electrical conductors are electrically connected to the output of the first and second notches, that is to say that the electrical connection is formed on the electrical conductors just after their exit from the two notches, at an axial end of the mass stator. The electrical connection can be made in a plane perpendicular to the axis of rotation of the machine. The plane of the electrical connection can be away from the stator mass by less than 60 mm, better still by less than 40 mm, for example by approximately 27 mm or 38 mm.

A majority of the electrical conductors housed in a first notch can each be electrically connected to a respective second electrical conductor housed in a second notch, at the exit from said notches. At least one notch, better still a majority of the notches, or even more than half of the notches, better still more than two-thirds of the notches, or even all the notches, may comprise first electrical conductors each electrically connected to a respective second electrical conductor housed in a second notch, at the exit of said notches.

In one embodiment, all the electrical conductors having a free end located at the same circumferential position around the axis of rotation of the machine, regardless of their radial position, are electrically connected together.

The first and second electrical conductors can each have an oblique portion. The oblique portions may extend in a circumferential direction, around the axis of rotation of the machine. The two oblique portions can be configured to converge towards one another and thus allow the electrical connection to be made.

An electrical conductor can have two oblique portions, one at each of its two ends. The two oblique portions of the same electrical conductor can extend in opposite directions. They can be symmetrical to each other.

A majority of the electrical conductors can include one or more oblique portions as described above.

The electrical conductors can be arranged in the notches in a distributed manner. By “distributed”, it should be understood that the outgoing and return electrical conductors are each housed in different and non-consecutive notches. At least one of the electrical conductors can pass successively through two non-consecutive notches.

The electrical conductors can form a distributed, whole or fractional coil. The winding can be full in pitch with or without shortening, or in a fractional variant.

Another subject of the invention, independently or in combination with the above, is a stator of a rotating electrical machine, comprising a stator mass comprising notches, electrical conductors being housed in the notches and forming a fractional winding, each of the notches being continuously closed contour.

The stator may have one or more of the characteristics mentioned above or below. In particular, at least part of the electrical conductors, or even a majority of the electrical conductors, may be in the shape of pins, in particular of a U or I, and extend axially in the notches.

The electrical conductors can form a distributed coil. The winding is not concentrated or wound on tooth.

In the case where the winding is fractional, the number of notches per pole and per phase is fractional. The winding is in the invention whole or fractional. The winding can be full in pitch with or without shortening, or in a fractional variant. In one embodiment, the electrical conductors form a fractional coil, 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 q = d (2pm) is written in the form of an irreducible fraction z / n, z and n being two undamaged integers, n being different from 1, where Ne is the number of notches of the stator, m the number of phases of the winding and p the number of pairs of poles of the stator.

The number of notches in 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 still being 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 of number of notches / number of stator poles can be chosen from the combinations of the following list, which is not restrictive: 30/4, 42/4, 45/6, 63/6, 60/8, 84/8. In one embodiment, the number of notches / number of stator poles combination is 63/6 or 60/8.

In one embodiment, the number of notches / number of stator poles combination is 60/8. In this case, we have <7 = 60 / (2 * 4 * 3) = 5/2.

In one embodiment, the combination of number of notches / number of pairs of stator poles is 63/6 or in this case we have <7 = 63 / (2 * 3 * 3) = 7/2.

More broadly, the combination between the number of Ne notches and the number of p-pole pairs of the stator can be one of those checked in Table 1 below.

[Table 1]

The number of phases is in this case three, but it is not beyond the scope of the present invention if the number of phases is different, being for example two, the machine then comprising a two-phase coil, or being for example 5, 6 or 9. Preferably, the coil is polyphase.

The electrical conductors can be placed in series in a so-called corrugated winding or in a so-called nested winding.

The term “corrugated winding” is understood to mean a winding in which the electrical conductors of the same phase and of the same pole are electrically connected to each other so that, for a winding path, the electric current of the phase circulates in the electrical conductors, rotating around the axis of rotation of the machine, always in one direction. For a winding track, the electrical conductors of the same phase and the same pole do not overlap when viewed perpendicular to the axis of rotation of the machine.

By “nested winding” is meant a winding in which the electrical conductors of the same phase of the same pole are electrically connected to one another so that the electric current of the phase flows through the electrical conductors in rotating around the axis of rotation of the machine alternately in one direction then in the other. For a winding track, the electrical conductors of the same phase and the same pole overlap when viewed perpendicular to the axis of rotation of the machine.

The winding can have a single winding path or several winding paths. In an "electrical conductor" flows the current of the same phase by winding. By "winding path" is meant all the electrical conductors of the machine which are traversed by the same electric current of the same phase. These electrical conductors can be connected to each other in series or in parallel or in series-parallel. In the case where there is only one channel, the electrical conductors are connected in series. In the case where there are several channels, the electrical conductors of each channel are connected in series, and the channels are connected in parallel.

The electrical conductors can be arranged in a row in the notches. By “row” is meant that the electrical conductors are not arranged in the slots in bulk but in an orderly manner. They are stacked in the notches in a non-random manner, being for example arranged in one or more rows of aligned electrical conductors, in particular in the radial and / or circumferential direction. The electrical conductors may have a generally rectangular cross section, in particular with rounded edges. The circumferential dimension of an electrical conductor can correspond substantially to the width of a notch. Thus, a notch may have in its width only one electrical conductor. The width of the notch is measured in its circumferential dimension around the axis of rotation of the machine.

Electrical conductors can be adjacent to each other by their long sides, otherwise called the flat.

Optimization of the stack can allow a greater quantity of electrical conductors to be placed in the slots and thus obtain a stator of greater power, at constant volume.

Each notch can include two to 36 electrical conductors, in particular two to 24, better still 2 to 12 electrical conductors. Each notch may include two to eight electrical conductors, in particular two to six electrical conductors, in particular two to four electrical conductors, for example two or four electrical conductors. In an alternative embodiment, each notch has two electrical conductors. In another variant embodiment, each notch has four electrical conductors.

In an "electrical conductor" flows the current of the same phase of a winding track.

Pins

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

The hairpin and flat electrical conductors increase the fill factor of the slot, making the machine more compact. Thanks to a high filling coefficient, the thermal 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.

In addition, the manufacture of the stator can be facilitated by the electrical conductors in the form of pins. In addition, the winding with pins can be easily modified by changing only the connections between the pins at the heads. of coils. Finally, since the pins do not need to have open notches, it is possible to have closed notches which allow the pins to be held and it is therefore possible to eliminate the step of inserting the stator shims.

Electrical conductors, or even a majority of electrical conductors, extend axially into the notches. The electrical conductors can be introduced into the corresponding notches through 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.

A U-shaped electrical conductor has two axial ends both placed at one of the axial ends of the stator. It passes through two different slots, and can be welded at each of its axial ends to two other electrical conductors, at the same axial side of the stator. The bottom of the U is on the other axial side of the stator.

Strands

In one embodiment, each electrical conductor can 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 "wire", or flat. The flat strands can be shaped into pins, for example a U or an I. Each strand is coated with an insulating enamel.

The fact that each notch can include several conductors and / or several strands makes it possible to minimize losses by induced currents, or Joule AC losses, which is particularly advantageous when the operating speed is high. It is thus possible to obtain better efficiency at high speed.

The presence of the closed notches can make it possible to obtain a reduction in the flow of leaks seen by the conductors, which results in a decrease in eddy current losses in the strands.

In one embodiment, each electrical conductor may include one or more pins, each forming a strand, as explained above. In this case, all the strands of the same electrical conductor can be electrically connected to each other at the outlet of the notch. The strands electrically connected to each other are placed short-circuited. The number of strands electrically connected together may 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 flows through all strands of the same electrical conductor. All the strands of the same electrical conductor can be electrically connected to each other, especially at the exit of 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 strands of all electrical conductors having a free end located at the same circumferential position around the axis of rotation of the machine, regardless of their radial position, can be electrically connected to each other.

In one embodiment, each electrical conductor has a single strand. In another embodiment, each electrical conductor has three strands.

In the case where a notch has two electrical conductors, a notch can therefore accommodate two strands, or in a variant six strands, for example, distributed between the two electrical conductors.

As a variant, a notch has four electrical conductors. Each electrical conductor can have two strands. The notch then accommodates eight strands, distributed between the four electrical conductors.

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 the losses by eddy currents in the strands.

A strand may have a width of between 1 and 5 mmm, being for example of the order of 2.5 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 of between 1 and 4 mmm, for example being of the order of 1.6 or 1.8 mm. The height of a strand is defined as its thickness in the radial dimension.

A ratio of the width of a strand to its height can be between 1 and 2.5, better still between 1.2 and 2, or even between 1.4 and 1.8, being for example 1.56 or 1 , 66. In another embodiment, a strand may have a height of between 2 and 8 mm, being for example of the order of 4.75 mm. The height of a strand is defined as its thickness in the radial dimension. A ratio of the width of a strand to its height may be less than 1, for example between 0.9 and 0.2, or even between 0.8 and 0.3, being for example from 0.5 to 0.6 about.

The electrical conductors can be made of copper or aluminum.

Insulators

The electrical conductors are electrically isolated from the outside by an insulating coating, including enamel. The electrical conductors can be separated from the walls of the notch by an insulation, in particular by at least one sheet of insulation. Such a sheet insulation allows better insulation of the electrical conductors with respect to the stator mass. The use of closed notches can improve the retention of insulation around electrical conductors in the notches.

Bridges of matter

The stator mass may include teeth formed between the notches, which are interconnected on the side of the air gap by material bridges. Thus, each notch is closed on the side of the air gap by a material bridge connecting between them two consecutive teeth of the stator mass. The material bridges each connect two teeth adjacent to their base on the air gap side and define the bottom of the notch between these teeth on the air gap side.

The material bridges are integral with the adjacent teeth.

The two consecutive teeth are connected on the opposite side by a yoke. The cylinder head is made in one piece with the teeth. The stator is thus devoid of a yoke attached to a serrated crown.

As mentioned above, the absence of opening of the notches towards the air gap makes it possible to avoid producing electromagnetic disturbances, in particular an increase in the “magnetic” air gap due to the flux fringes, higher iron losses. at the rotor surface for the same reason, or alternatively pulsating torques, and radial forces, and Joule AC losses. The electromagnetic performance of the machine is improved. The bridges of material can be made so as to be magnetically saturated during machine operation. This limits the flow of flow from one notch to another without preventing the flow of flow from the rotor to the stator.

The bridges of material are preferably undeformable. This increases the stiffness of the stator and improves the life of the electrical machine.

The smallest width of the bridges of material is for example between 0.2 and 0.5 mm. It can be of the order of 0.35 mm, for example.

The width of the material bridge can be of the same order of magnitude as the thickness of the sheet.

For example, the stator mass is in the form of stacked sheet metal, having teeth interconnected at their base on the side of the air gap by bridges of material.

The bridges of matter came in one piece with the teeth.

Grooves

The bridges of material may have at least one localized constriction formed by at least one groove. To obtain saturation, the section of the material bridge available for the passage of the flow can be locally reduced, for example by providing a groove.

Preferably, the grooves are open towards the notches.

The bottom of the notches on the side of the material bridge has at least one bearing surface, better still at least two bearing surfaces, oriented transversely and the bottom of the groove is set back relative to this or these surfaces. The bearing surface (s) may be oriented obliquely with respect to the radial axis of the corresponding notch or oriented perpendicular to this axis. The groove forms a break in slope with respect to the bearing surface (s). The electrical conductors, preferably of substantially rectangular cross section, inserted into the corresponding notch, are preferably resting against the bearing surfaces and set back relative to the bottom of the groove. Preferably, the electrical conductors are without contact with the groove. The support surface or surfaces are preferably flat. The bottom of the notch can be flat, except for the groove. This allows good filling of the notches by the electrical conductors in the case of electrical conductors of rectangular cross section, by allowing the coils to rest flat in the bottom of the notches. The groove in the bottom of the notch preferably forms a clearance between the material bridge and the corresponding electrical conductor.

The material bridge may include at least two grooves as described above, for example two grooves per notch.

The groove or grooves can be centered with respect to the notch or notches, or on the contrary be offset with respect to a plane of symmetry of the notch or notches.

Preferably, the groove or grooves are each of curved profile in section in a plane perpendicular to the axis of the stator, in particular of substantially semi-circular section. The bottom of the groove may be in the form of an arc of a circle, or of any other suitable shape, for example semi-elliptical or wavy.

The internal surface of the stator is preferably cylindrical of revolution.

Notches

At least one notch, more preferably all notches, may be generally rectangular in cross section.

At least one notch, better still all the notches, may include radial edges having a rib, each in particular a rib. The rib can improve the retention of electrical conductors in the notches. In addition, the rib can help minimize AC losses.

The rib may extend parallel to the axis of rotation of the machine.

The rib can be placed in a central part of the radial edges, for example halfway between the bottom of the notch and the bridge of material closing it. As a variant, at least one notch, better still all the notches, can comprise radial edges each having several ribs, for example two or three. This can be particularly useful in the case where the notch is intended to receive three, four, six or eight electrical conductors. The notch may have a rib between each of the layers of electrical conductors.

In an alternative embodiment, the radial edges are rectilinear, being devoid of ribs.

At least one notch may have opposite radial edges parallel to each other, better all the notches have radial edges parallel to each other. The width of a notch is preferably substantially constant over its entire height. There is thus a better filling rate of the notches. As a variant, the radial edges of the notches are not parallel to each other.

At least one notch, better all notches, can have a rectilinear, arcuate or other bottom. The bottom of the notch is the bottom of the notch located on the cylinder head side, opposite the material bridge and the air gap.

At least one notch, better all notches, can have a ratio of notch length to width between 2 and 6, better still between 3 and 4. The width of a notch corresponds to its dimension in the circumferential direction measured around the axis of rotation of the machine, and its length to its dimension in the radial direction.

The stator may include a sensor for measuring the temperature of the electrical conductors, the sensor being arranged in the notch, for example a thermocouple. This sensor can be housed at least partly in the groove of the material bridge closing the notch. The sensor is for example housed in a space between the conductor closest to the material bridge and the material bridge.

The notches can be configured to allow the passage of a coolant. Some or all of the notches can accommodate conduits for circulating a coolant, or the coolant can flow directly through the notches. The cooling fluid can circulate in the bottom of the notch, and / or towards the material bridge, and / or between the electrical conductors, for example between two layers of electrical conductors. The coolant can be a gas, for example air, or a liquid, for example water or oil.

At least one tooth, better still all teeth, may be generally trapezoidal in cross section. At least one tooth, better all teeth, may have divergent edges as one moves away from the axis of rotation of the machine.

The stator mass can be produced by stacking sheets. The teeth are connected to each other by bridges of material, and on the opposite side by a cylinder head. Closed notches can be produced entirely by cutting from the sheets. Each sheet of the stack of sheets can be made in one piece.

Each sheet is for example cut from a magnetic steel sheet or one 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 their assembly within the stack. Electrical insulation can also be obtained by heat treatment of the sheets, if necessary.

Alternatively, the stator mass can be made from compacted or agglomerated magnetic powder.

Machine and rotor

Another subject of the invention is a rotating electrical machine, such as a synchronous motor or a synchronous generator, comprising a stator as defined above. The machine can be synchronous or asynchronous. The machine can be reluctance. It can constitute a synchronous motor.

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 at 15,000 rpm. min, or even 20,000 rpm or 25,000 rpm. The maximum speed of rotation of the machine may be less than 100,000 rev / min, or even 60,000 rev / min, or even less than 40,000 rev / min, better still less than 30,000 rev / min.

The rotating electric machine may include a rotor. The rotor can be permanent magnet, with surface magnets or buried. The rotor can be in flux concentration. It may have one or more layers of magnets arranged in an I, U or Y arrangement. Alternatively, it may be a wound or squirrel cage rotor, or a variable reluctance rotor.

The diameter of the rotor may be less than 400 mm, better still less than 300 mm, and greater than 50 mm, better still greater than 70 mm, being for example between 100 and 200 mm.

The rotor may have a rotor mass extending along the axis of rotation and disposed around a shaft. The shaft may include torque transmission means for rotating the rotor mass.

The rotor may or may not be cantilevered.

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

Manufacturing process

A further subject of the invention, independently or in combination with the above, is a method of manufacturing a stator for a rotating electrical machine, in particular of a stator as defined above, in which electrical conductors are placed in the notches of a stator mass of the stator by introducing them into the corresponding notches via one or both axial ends of the stator.

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

Two I-shaped electrical conductors can be connected together beforehand in two different non-consecutive notches of the stator mass of the stator. In case an electrical conductor is I-shaped, it can be soldered to two other electrical conductors on two opposite sides of the machine.

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

Brief description of the drawings

The invention may be better understood from reading the detailed description which follows, of non-limiting embodiments thereof, and by examining the appended drawing, in which:

[Fig 1] Figure 1 is a perspective view, schematic and partial, of a stator made in accordance with the invention.

[Fig 2] FIG. 2 is a detail view, in perspective, of the stator of FIG. 1.

[Fig 3] Figure 3 shows in cross section, schematically and partially, the stator mass of the stator according to the invention.

[Fig 3 a] Figure 3 a also shows in cross section, schematically and partially, the stator mass of the stator according to the invention.

[Fig 4] Figure 4 illustrates the variation of the radial air gap field, in Tesla, as a function of the angular position in °.

[Fig 5] Figure 5 is a perspective view of an alternative embodiment.

[Fig 6] Figure 6 is a detail view, in perspective, of the stator of Figure 5.

[Fig 7] Figure 7 shows in cross section, schematically and partially, an alternative embodiment. [Fig 8] Figure 8 shows in cross section, schematically and partially, an alternative embodiment.

[Fig 9] Figure 9 shows in cross section, schematically and partially, an alternative embodiment.

[Fig 10] Figure 10 shows in cross section, schematically and partially, an alternative embodiment.

[Fig 11] Figure 11 shows in cross section, schematically and partially, an alternative embodiment.

[Fig 12] Figure 12 shows in cross section, schematically and partially, an alternative embodiment.

detailed description

There is illustrated in Figures 1 to 3 a stator 2 of a rotating electrical machine 1 also comprising a rotor not shown. The stator is used to generate a rotating magnetic field to drive the rotating rotor, as part of a synchronous motor, and in the case of an alternator, the rotation of the rotor induces an electromotive force in the electrical conductors of the stator.

The examples illustrated below are schematic and the relative dimensions of the various constituent elements have not necessarily been observed.

The stator 2 comprises electrical conductors 22, which are arranged in notches 21 formed between teeth 23 of a stator mass 25. The notches 21 are closed.

The notches 21 are closed on the side of the air gap by bridges of material 27, each connecting two consecutive teeth of the stator mass 25, and on the opposite side by a yoke 29. The latter and the teeth 23 are in one piece. . The cylinder head 29 may be traversed, where appropriate, by longitudinal ribs of semi-circular section 31 intended to house ducts for circulating a cooling liquid.

The electrical conductors 22 are for the most part in the form of pins, namely U or I, and extending axially in the notches. A first electrical conductor housed in a first notch is electrically connected to a second electrical conductor housed in a second notch, at the outlet from said notches. The first and second notches are non-consecutive. In the examples illustrated, they are separated by 7 and 10 other notches respectively. Alternatively, the first and second notches are separated by 3, 4, 5, 6, 8, 9, or 11 other notches, for example.

In particular, FIG. 2 shows the end surfaces 22a of the first and second electrical conductors intended to receive the electrical connection. The electrical connection is made in a plane perpendicular to the axis of rotation of the machine. The plane of the electrical connection may be away from the stator mass by less than approximately 40 mm, in particular by approximately 35 mm.

The electrical connection is formed on the electrical conductors just after their exit from the two notches, at one axial end of the stator mass. The two conductors each have an oblique portion 22b, which converge towards each other.

The electrical conductors are arranged in the notches in a distributed manner, and they form a distributed coil, which in the example described is fractional. In this example, the number of notches is 60. The number of stator poles is 8. So the combination of number of notches / number of stator poles is 60/8.

The electrical conductors form a fractional winding, for which the ratio q defined by q = d (2pm) is written in the form of an irreducible fraction z / n, z and n being two undamaged whole numbers, n being different from 1, where Ne is the number of notches of the stator, m the number of phases of the winding and p the number of pairs of poles of the stator. We then have q = 60 / (3 x 8) = 5/2 for this machine with 60 notches and 8 poles.

The electrical conductors 22 are arranged in a row in the notches 21, in a row of aligned electrical conductors.

The electrical conductors may have a generally rectangular cross section, in particular with rounded corners. They are in the example described superimposed radially in a single row. The circumferential dimension of an electrical conductor corresponds roughly to the width of a notch. Thus, the notch has only one electrical conductor in its width. It can include several electrical conductors in its radial dimension. It has two in the example described.

The electrical conductors 22 are made of copper or aluminum, or any other conductive material enamelled or coated with any other suitable insulating coating. The variation of the radial air gap field due to the armature reaction alone, in Tesla, as a function of the angular position in °, has been illustrated in FIG. Curve A illustrates this variation for a stator with closed slots in accordance with the invention, and is presented in comparison with curve B which illustrates this variation for a stator with semi-open slots, with an opening of 2 mm. It can be seen that the radial air gap field obtained with a stator according to the invention (curve A) is less rich in harmonics.

In the example which has just been described, a notch has two electrical conductors of different phases, and each electrical conductor is formed from a single strand.

In the variant embodiment of Figures 5 and 6, each electrical conductor has several pins, each forming a strand 32 within a notch. Thus, each electrical conductor has three strands 32. All the strands 32 of the same electrical conductor 22 are electrically connected to each other at the outlet of the notch, and to each of their two axial ends 22a.

Furthermore, the stator of Figures 5 and 6 has 63 notches and 6 poles of the stator. Thus, the combination of number of notches / number of stator poles is 63/6.

Thus, the electrical conductors form a fractional winding, for which the ratio q defined by q = d (2pm) is written in the form of an irreducible fraction z / n, z and n being two undamaged whole numbers, n being different from 1, where Ne is the number of stator notches, m the number of phases of the winding and p the number of pairs of stator poles. We then have q = 63 / (3> <6) = 7/2 for this machine with 63 notches and 6 poles.

Each electrical conductor 22 is surrounded by an insulating sheet not visible in the figures, making it possible to insulate the electrical conductors of the walls 33 and 36 of the notch and the electrical conductors 22 of different phases between them within a notch.

The notches 21 are, in the examples described and as shown in Figure 3, with radial edges 33 parallel to each other, and are in section in a plane perpendicular to the axis of rotation of the machine of substantially rectangular shape.

The bottom 35 of the notches 21 is of substantially complementary shape to that of the electrical conductors 22, with the exception of a groove 40, as can be seen in Figure 3.

The bottom 35 of the notches 21 is connected to the radial edges 33 by rounded edges 38. The groove 40 of each notch 21 is centered on the bottom of the notch 35 and extends along of the axis of rotation of the machine. In an alternative embodiment not shown, the groove is not centered, or the bottom 35 has several grooves.

The grooves 40 have, in section in a plane perpendicular to the axis of rotation, a rounded shape, in particular substantially semi-circular. They have a depth p of between 0.3 mm and 0.6 mm, for example equal to 0.5 mm.

The presence of the grooves 40 leads to a localized narrowing of the bridges of material 27. Such a narrowing allows a magnetic saturation of the sheet for a lower magnetic flux along the bridge 27, which limits the passage of the magnetic flux.

The smallest width / of the material bridges 27 is preferably between 0.2 mm and 0.5 mm, for example equal to 0.35 mm.

An angle a can be defined between the tangent to the bore of the stator at the level of a central axis of the notch, which can be an axis of symmetry for the latter, and an axis passing through the edge of the groove 40 and by a rounding 38 of the notch, as illustrated in Figure 3a. This angle α may be within a range of 20 ° to 35 °, better still from 21 ° to 30 °, or even from 22 ° to 28 °, being for example approximately 25 °.

The notches are generally rectangular in cross section. All or part of the notches may have radial edges 33 having a rib 42, as illustrated in Figures 7 and 8. Each rib 42 extends parallel to the axis of rotation of the machine. This rib 42 is placed in a central part of the radial edges 33, substantially halfway between the bottom of the notch 36 on the side of the cylinder head 29 and the material bridge 27 closing it.

The notches may have a rectilinear bottom 36, as illustrated in Figures 3, 7 and 8. As a variant, the bottom 36 of the notch 21 on the side of the cylinder head 29 may be in the shape of a circular arc, concave towards the bottom. 'notch, as shown in Figures 9 to 12.

The embodiments of Figures 11 and 12 differ from the previous ones by the presence of additional ribs 42, which are arranged near the material bridge 27, at the level of the roundings 38 of the bottom 35 of the notches on the side of the air gap.

The embodiments of Figures 8, 10 and 12 differ only from those of Figures 7, 9 and 11 by the presence of conductors 22 with several strands 32, in place of the single-strand conductors 22 of Figures 7, 9 and 11.

The stator mass 25 is formed from a bundle of magnetic sheets stacked along the axis of rotation, the sheets being for example identical and exactly superimposed. They can be held together by clipping, gluing, rivets, tie rods, welds and / or any other technique. The magnetic sheets are preferably made of magnetic steel. The teeth 23 of the stator mass 25 may have complementary surface reliefs making it possible to clip the various sheets making up the stator mass 25 together.

The stator can be obtained by means of a manufacturing process in which the electrical conductors 22 are inserted into the notches 21 by one or both axial ends of the stator, by sliding in the notches 21 along an axis parallel to the stator. longitudinal axis of rotation.

In the invention, all the electrical conductors having their free end located at the same circumferential position around the axis of rotation of the machine are electrically connected together, regardless of their radial position.

Of course, the invention is not limited to the embodiments which have just been described, and the rotor associated with the stator described can be wound, with a squirrel cage or with permanent magnets, or else with variable reluctance.

Claims

1. Stator (2) of a rotating electrical machine (1), comprising a stator mass (25) comprising notches (21), electrical conductors (22) being housed in the slots, at least part of the electrical conductors, or even one majority of the electrical conductors, being in the shape of a pin, in particular of a U or I, and extending axially in the notches, at least a first electrical conductor housed in a first notch being electrically connected to a second electrical conductor housed in a second notch, at the exit from said notches, each of the notches having a continuously closed contour, at least one notch (21) comprising radial edges having one or more ribs (42).

2. Stator (2) of a rotating electrical machine (1), comprising a stator mass (25) comprising notches (21), electrical conductors (22) being housed in the notches, at least part of the electrical conductors, or even one. majority of the electrical conductors, being in the shape of a pin, in particular of a U or I, and extending axially in the notches, at least a first electrical conductor housed in a first notch being electrically connected to a second electrical conductor housed in a second notch, at the exit of said notches, each of the notches having a continuously closed contour, the stator mass comprising teeth (23) formed between the notches (21), which are interconnected on the side of the air gap by bridges of material (27) which define a bottom (35) of the notches (21) on the side of the air gap, the bottom (35) of the notches (21) on the side of the air gap being connected to the radial edges (33) of the notches by rounding (38).

3. Stator (2) of a rotating electrical machine (1), comprising a stator mass (25) comprising notches (21), electrical conductors (22) being housed in the slots, at least part of the electrical conductors, or even a part. majority of the electrical conductors, being in the shape of a pin, in particular of a U or I, and extending axially in the notches, at least a first electrical conductor housed in a first notch being electrically connected to a second electrical conductor housed in a second notch, at the exit of said notches, each of the notches having a continuously closed contour, the stator mass comprising teeth (23) formed between the notches (21), which are interconnected on the side of the air gap by bridges of material (27) which define a bottom (35) of the notches (21) on the side of the air gap, the material bridges having at least one localized constriction formed by at least one groove, the groove (s) being centered with respect to the notch (s).

4. Stator (2) of a rotating electrical machine (1), comprising a stator mass (25) comprising notches (21), electrical conductors (22) being housed in the slots, at least part of the electrical conductors, or even a part. majority of the electrical conductors, being in the shape of a pin, in particular of a U or I, and extending axially in the notches, at least a first electrical conductor housed in a first notch being electrically connected to a second electrical conductor housed in a second notch, at the exit of said notches, each of the notches having a continuously closed contour, the stator mass comprising teeth (23) formed between the notches (21), which are interconnected on the side of the air gap by bridges of material (27) which define a bottom (35) of the notches (21) on the side of the air gap, the material bridges having at least one localized constriction formed by at least one groove, the groove or grooves each being profile curved in section in a plane perpendicular to the axis of the stator, being of substantially semi-circular section, in the shape of an arc of a circle, or semi-elliptical or wavy.

5. Stator (2) of a rotating electrical machine (1), comprising a stator mass (25) comprising notches (21), electrical conductors (22) being housed in the slots, at least part of the electrical conductors, or even a part. majority of the electrical conductors, being in the shape of a pin, in particular of a U or I, and extending axially in the notches, at least a first electrical conductor housed in a first notch being electrically connected to a second electrical conductor housed in a second notch, at the exit of said notches, each of the notches having a continuously closed contour, the stator mass comprising teeth (23) formed between the notches (21), which are interconnected on the side of the air gap by bridges of material (27), the smallest width of the material bridges being between 0.2 and 0.5 mm.

6. Stator according to one of the preceding claims, the electrical conductors (22) being in cross section of generally rectangular shape.

7. Stator according to one of the preceding claims, each notch (21) comprising two to eight electrical conductors (22), in particular two to six electrical conductors, each electrical conductor possibly comprising one or more strands (32).

8. Stator according to any one of the preceding claims, in which all the electrical conductors (22) having a free end (22a) situated at the same circumferential position around the axis of rotation of the machine, whatever their position. radial, are electrically connected together.

9. Stator according to the preceding claim, the stator mass comprising teeth (23) formed between the notches (21), which are interconnected on the side of the air gap by material bridges (27), and on the opposite side by a cylinder head (29).

10. Stator according to the preceding claim, the material bridges (27) having at least one localized constriction formed by at least one groove (40).

11. Stator according to any one of the preceding claims, in which at least one notch (21), better still all the notches, has radial edges having a rib (42), each in particular a rib (42).

12. Stator according to any one of the preceding claims, in which at least one notch (21), better all the notches, has radial edges (33) parallel to each other.

13. A stator according to any one of the preceding claims, wherein at least one notch (21), better all the notches, has a bottom (36) rectilinear or in the form of an arc of a circle.

14. Stator according to any one of the preceding claims, in which at least one notch (21), better all the notches, has a ratio of the length of the notch to its width of between 2 and 6, better between 3 and 4.

15. Stator according to any one of the preceding claims, comprising a sensor for measuring the temperature of the electrical conductors, arranged in the notch, for example a thermocouple.

16. A stator according to any preceding claim, wherein the notches (21) are configured to allow the passage of a cooling fluid.

17. Rotating electric machine (1) comprising a stator (2) according to any one of the preceding claims and a rotor (1).

18. A method of manufacturing a rotating electrical machine stator according to any one of claims 1 to 16, wherein there are electrical conductors (22) in the notches (21) of a stator mass (25) of the stator. in them introducing into the corresponding notches via one or both axial ends of the machine.

19. Method according to the preceding claim, wherein all the electrical conductors (22) having a free end (22a) located at the same circumferential position around the axis of rotation of the machine are electrically connected together, regardless of their position. radial.