EP4295469A1

EP4295469A1 - Rotor for a rotary electric machine

Info

Publication number: EP4295469A1
Application number: EP22705437.6A
Authority: EP
Inventors: Radu Fratila; Sara BAZHAR; Mohand Ou Ramdane HAMITI
Original assignee: Nidec PSA Emotors SAS
Current assignee: Nidec PSA Emotors SAS
Priority date: 2021-02-22
Filing date: 2022-01-26
Publication date: 2023-12-27
Also published as: WO2022175614A1; FR3120168A1; US20240120785A1

Abstract

Rotor (30) for a rotary electric machine, comprising a rotor body (33) comprising metal sheets stacked one on top of the other, the rotor body (33) comprising a plurality of housings (10) for receiving one or more permanent magnets defining poles of the rotor, the housings of a pole being arranged in at least one first (11) and one second (12) row of housings, the first row of housings comprising three U-shaped housings, with a central housing and two side housings, a length (L2) of a larger rectangle enclosed in the central housing being equal to +/- 20% of the length (L1) of the largest rectangle enclosed in a side housing, at least one of the side housings, in particular the two side housings of the first row, comprising a recess (15) which extends from the side housing to the central housing.

Description

Title: Rotor of rotating electric machine

The present invention claims the priority of French application 2101695 filed on February 22, 2021, the content of which (text, drawings and claims) is incorporated herein by reference.

Technical area

The present invention relates to rotating electrical machines, motors or generators, and more particularly the rotors of such machines. The invention relates to rotors with permanent magnets.

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

Permanent magnet rotors are generally composed of a rotor mass and permanent magnets of various geometric shapes. The rotor mass may comprise a stack of thin cut-out magnetic laminations. It can comprise one or more stacks of sheets stacked on top of each other.

The permanent magnets can be arranged on the surface, directly facing the air gap or, as a variant, be arranged inside the rotor mass, in housings of the latter, being then said to be “buried” or “embedded”.

In this case, they can be arranged in a row, as for example in application US 2007/0096578, in which the magnet housings have ends rounded in a semicircle, as well as in application US 2007/0096577.

In applications CN110212666, US 2013/0020889 and CN 206650521, there is a permanent magnet arranged on the surface and a single row of buried magnets. In applications US 2008/007131, WO 2019/179864 and KR 10-2018229, the permanent magnets of the two rows are arranged in a V.

In application WO 2019/174323, the rows are arranged such that two adjacent magnets of two consecutive poles are parallel to each other and two magnets of two rows are also parallel to each other.

There is a need to improve the magnetic performance and in particular the volume torque of rotating electrical machines, and to reduce their cost of manufacture and assembly.

Summary of the invention

The invention aims to meet this need and thus has as its object, according to one of its aspects, a rotor of a rotating electrical machine, a rotor mass comprising laminations stacked on top of each other, the rotor mass comprising a plurality of housings, at least part of the housings, see all the housings, receiving one or more permanent magnets defining poles of the rotor, the housings of a pole being arranged in at least a first and a second row of housings, the first row of housing comprising three housings arranged in a U, with a central housing and two lateral housings, a length of a largest rectangle inscribed in the central housing being equal to +/- 20% of the length of the largest rectangle inscribed in a lateral housing , at least one of the side housings, in particular the two side housings of the first row, comprising a recess which extends from the side housing towards the central housing.

Advantageously, the presence of two rows of housings makes it possible to increase the number of magnets received in the rotor mass, and thus to increase the resulting power density. It is thus possible to obtain more torque with the same rotor size. The invention advantageously makes it possible to improve the reluctant torque of the machine.

Disclosure of Invention The 'length' is measured along the axis of the row of slots. We speak of 'width' to designate the dimension perpendicular to the length in the plane of a transverse section of the rotor mass.

The length of the largest rectangle inscribed in the central housing may be equal to +/- 20% to the length of the largest rectangle inscribed in a side housing, or even to +/- 17%, better still to +/-15%, or even at +/- 10%, even better at +/-7%, or even at +/- 5%. In this report, the length of the largest rectangle inscribed in a side recess is taken as a reference.

In one embodiment, the length of a second row magnet may be equal to the length of a first row magnet. All the magnets of a pole can have the same length.

In one embodiment, the rotor comprises a first and a second row of housings per pole, being devoid of any additional row.

The second row can be closer to the air gap than the first row. The first row is farther from the air gap than the second row.

The first row can comprise a central housing and two side housings. The two side housings are symmetrical to each other with respect to an axis of the pole.

The rotor mass may comprise one or more stacks of laminations stacked on top of each other. Each stack of laminations can comprise at least one housing receiving the permanent magnet. In the case where the rotor mass comprises several stacks of laminations stacked on top of each other, the rotor mass may comprise, for a housing, a single or several permanent magnets, for example one permanent magnet per laminations package.

The width of the largest rectangle inscribed in the central slot can be equal to +/- 50% to the width of the largest rectangle inscribed in a side slot, better at 40%, even better at 30%, or even at +/- 20 %, better at +/-15%, even at +/- 10%, even better at +/- 7%, even at +/- 5%. In this report, the width of the largest rectangle inscribed in a side recess is taken as a reference.

The width B of the central housing can be equal to the width B of a side housing.

The width A of a housing of the second row can be less than the width B of a housing of the first row. A (BA)/B ratio can be between 0 and 40%, better between 5 and 35%, or even between 10 and 30%, being for example of the order of 25%. In one embodiment, it is possible to have the width B of a housing of the first row equal to 3.7 mm and the width A of a housing of the second row equal to 2.8 mm.

In one embodiment, the width A of a slot in the second row may be equal to the width B of a slot in the first row. All the housings of a pole can have the same width A.

The number of sizes of permanent magnets required can be advantageously reduced to two or three at most, or even to only one.

The side pockets of the first row can be provided with permanent magnets. The permanent magnets of the side housings of the first row can be identical to each other. They may in particular have the same size in cross section.

The central housing of the first row can be provided with one or more permanent magnets, or, as a variant, be devoid of them. Depending on the choice for the presence or not of a central permanent magnet, the rotor can advantageously allow a certain modularity for the resulting machine.

The center housing of the first row can be provided with a permanent magnet of the same size as the permanent magnets of the side housings.

Alternatively, the central housing of the first row can be provided with a smaller permanent magnet than the permanent magnets of the side housings. This is advantageous from an electromagnetic point of view. Indeed, the permanent magnet being smaller than the housing, there is a part of the housing which happens to be empty on the sides of the magnet, which empty part makes it possible to reduce electromagnetic leakage.

In another variant embodiment, the central housing of the first row is empty.

The housings of the second row may be arranged in a V. The second row may in particular comprise two housings arranged in a V. They may be symmetrical to one another with respect to an axis of the pole. In one embodiment, all the housings of the second row are provided with permanent magnets. The V configuration of the second row saves space and avoids any risk of saturation of the magnetic circuit. In another alternative embodiment, the housings of the second row are empty, being devoid of magnets.

The second row permanent magnets can be identical to each other. They may in particular have the same size in cross section. The permanent magnets of the second row can have a different size from the permanent magnets of the first row, being for example smaller.

An angular opening a3 of the second row can be greater than or equal to twice the sum of the angular opening al between two consecutive poles and the angular opening a2 between the first and second rows. We can write a3 > 2 (al + a2). The angular openings are measured on the surface of the rotor, at the level of the air gap, for a given pole of the rotor.

An angular aperture a3 of the second row can be given by the following relation: a3 = k 2p/(2r), where p is the number of pairs of rotor poles and k the coefficient of pole opening, with the coefficient of polar opening k which is included in the interval [22.5%; 37.5%], better in the range [25%; 35%].

The choice of the value of the polar opening coefficient k makes it possible to optimize the resulting torque. In an exemplary embodiment, k is equal to 34.6%.

An angle a4 between the adjacent housings of two consecutive poles can be strictly greater than 0, being in particular between 5° and 35°, better still between 12° and 30°, being for example 24.8° in one embodiment. A strictly positive angle a4 increases the saliency torque. The choice of the value of the angle a4 makes it possible to improve the resulting torque.

The angle a4 may in particular be less than 55°, better still less than 50°, better still less than 40°, being in particular less than 35°. The two adjacent housings considered for the measurement of the angle a4 between the two consecutive poles are housings of the first row.

Each lateral housing of the first row forming with the central housing a bridge of material, the two bridges of material each having a longitudinal axis, the two axes being parallel to each other. This makes it possible to improve the mechanical strength and to obtain a better mechanical behavior to withstand the centrifugal force.

The axes of the material bridges can be parallel to an axis of the pole of the rotor. The recess may be configured to project radially from the central housing. The recess may protrude radially from the central housing by a distance Y of between 0 mm and twice the width of the central housing. This protrusion can make it possible to increase the path of the magnetic flux, which makes it possible to reduce flux leaks. It thus makes it possible to increase the reluctance because the path of the flux is lengthened while reducing the leakage flux.

The radial projection of the recess of the first row of housings can advantageously be associated with bridges of material between the side housings and the central housing which may be straight. The bridges of material between the lateral housings and the central housing may in particular extend along an axis which may be rectilinear. The two axes of the two material bridges of the first row can be parallel to each other. They can extend substantially radially. These axes may be parallel to the edges of the central housing. Such a configuration can make it possible to reduce the leakage fluxes and thus increase the electromotive force, as well as to increase the reluctance of the magnetic circuit and the torque, while increasing the mechanical strength of the material bridges. The torque can for example be increased by 200 rpm.

A width X of the recess can be between 0 mm and twice the width B of the central housing. The length Z of the recess can be between once the width B of the central housing and twice the latter.

These dimensions determine the size of the bridge of material between the side housings and the central housing. This material bridge has a minimum width conditioned by the mechanical strength constraints. Its width is substantially equal to at least the thickness of the magnetic sheet.

A radial dimension W between the bottom of the second row and the first row can be between once the width B of the central housing and three times the latter.

The recess may have an edge that extends at least partially parallel to an edge of the central housing.

At least one housing may include at least one abutment for holding the permanent magnet intended to be received in the housing. Each housing may include a stop located towards the air gap. The housings are each separated from the air gap by a material bridge whose width is conditioned by the mechanical strength constraints. Their width is substantially equal at least to the thickness of the magnetic sheet. The length of these bridges is substantially equal to the width of the housings.

The side housings can also include a stop located towards G obviously, for the maintenance of the permanent magnet.

The rotor may be devoid of circulation of cooling fluid in the housings. In particular, the recesses are not configured to allow the circulation of a cooling fluid.

A further subject of the invention, independently or in combination with the foregoing, is a rotating electrical machine rotor, comprising a rotor mass comprising laminations stacked on top of each other, the rotor mass comprising a plurality of housings, at least one part of the housings, see all the housings, receiving one or more permanent magnets defining poles of the rotor, the housings of a pole being arranged in at least a first and a second row of housings, the first row of housings comprising three housings arranged U-shaped, with a central housing and two lateral housings, a length L2 of a largest rectangle inscribed in the central housing being equal to +/- 20% to the length L1 of the largest rectangle inscribed in a lateral housing, at least one of the side housings, in particular the two side housings of the first row, comprising a recess which extends from the side housing towards the central housing, each log lateral element of the first row providing with the central housing a bridge of material, the two bridges of material each having a longitudinal axis, the two axes being parallel to each other.

Yrilled Rotor

In one embodiment, the rotor mass of the rotor may be composed of a plurality of packages arranged consecutively along an axis of rotation of the rotor, two consecutive packages being angularly offset around the axis of rotation of the rotor by an elementary angle 0r. The rotor may in particular comprise a first stack of laminations and a second stack of laminations.

Such a rotor is said to be 'twisted'. The rotor can advantageously be twisted, particularly in the case where the stator comprises a full-pitch winding. The invention can make it possible to reduce the number of packages necessary for the rotor. When the rotor is twisted, the reduction of torque ripples can be further improved.

Alternatively, the rotor may not be twisted. We then speak of a so-called ‘straight’ rotor. The rotor may advantageously be straight, particularly in the case where the stator comprises a fractional-pitch winding.

Rotor notches

At least one of the laminations of the rotor mass may comprise a plurality of notches on the surface of the rotor mass facing the air gap.

The notches of the rotor can all be identical or different. They may differ, for example, in their size and/or in their shape. The notches of the rotor can be provided facing the air gap, on the surface of the rotor or slightly buried.

The notches of the rotor can be identical to or different from the notches of the stator.

At least one notch of the rotor may have a shape, in the plane of the sheet, chosen from the following list, which is not exhaustive: partially circular, semi-circular, oblong, partially elliptical, polygonal, square, rectangular, rectangular with or without rounded corners, triangular, trapezoidal, dovetail, V-shaped or W-shaped.

In the case where the notch comprises a partially circular portion, for example semi-circular, its radius of curvature may be between 0.1 and 4 mm, better still between 0.36 and 3 mm, or even between 0.63 and 2 mm. , being for example of the order of 0.36 mm or 0.4 mm or 0.6 mm or 0.63 mm or 0.8 mm or 0.9 mm or 1 mm or 1 .2 mm or 1.26 mm or 1.4 mm or 1.6 mm or 1.8 mm.

The radius of curvature of a rounded corner can be less than half the width of a notch, measured circumferentially in the plane of the sheet. The radius of curvature of a rounded corner may be less than or equal to at least half the width ar of a notch and its depth br, measured radially in the plane of the sheet, i.e. min (br, ar/ 2).

At least one notch of the rotor may comprise a partially circular or even semi-circular portion, its radius of curvature R being between 0.4 e and 8 e, better still between 0.7 e and 4 e, being for example of the order of e, where e designates the width of the air gap of the machine comprising the stator.

At least one notch of the rotor can have a depth br, measured radially in the plane of the sheet, less than its width ar, measured circumferentially in the plane of the sheet.

As a variant, the depth, measured radially in the plane of the sheet, can be greater than the width of the notch of the rotor, measured circumferentially in the plane of the sheet.

The notches of the laminations of a first pack of the rotor mass can be angularly offset with respect to the notches of the laminations of a second pack of the rotor mass.

The rotor mass may comprise at least two stacks of laminations, or even at least three or four stacks. It can for example comprise two, three or four packs of sheets. The first and second packs of sheets can be consecutive.

The laminations of a stack of rotor laminations can all be identical to each other.

The laminations of each stack of laminations of the rotor may be identical between laminations of said stack.

The plates of two different packages can be identical to each other, being angularly offset or being turned over in order to obtain the angular offset of the notches. The sheets of two different packages can be identical to each other, not being returned. The two packages with identical sheets may or may not be consecutive. They can for example be separated by a stack of sheets having different sheets.

By “identical sheets”, it is mainly meant that said sheets are identical by the position of the notch(s).

Alternatively, the sheets of two different packages may be different from each other, the notch or notches not being placed in the same way or possibly having a different shape or size, or the number of notches being different.

By “different sheets”, it is mainly meant that said sheets differ from each other by the position of the notch(s) or by the number of notches.

In one embodiment, two sheets can have a different number of notches. In one embodiment, the detents are offset relative to a longitudinal axis of the rotor pole, which may be an axis of symmetry for the pole, by an offset angle. The sheets may in particular differ from each other by the value of the offset angle. The offset angle can be different between a sheet of the first package and a sheet of the second package.

The angular offset of the notches of two packages of the rotor can form a pattern with a regular offset or not, always in the same direction, or with a change of direction, for example herringbone, V, W, zig-zag.

Alternatively, the rotor may be devoid of notches on the surface of the rotor mass. The surface of the rotor mass can be substantially smooth.

Machine

Another subject of the invention is a rotating electrical machine comprising a stator and a rotor as defined above.

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 , 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.

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 work alone or be coupled to a gearbox. In this case, it is inserted into a casing which also houses a gearbox.

The machine has a stator. The latter comprises teeth defining notches between them. The stator may comprise electrical conductors, at least some of the electrical conductors, or even a majority of the electrical conductors, which may be pin-shaped U or I. Alternatively, the electrical conductors may include round wire.

The stator can be star or delta connected.

The machine may comprise a number of poles comprised between 2 and 48, better still between 4 and 24, or even between 6 and 12, being for example 6 or 8.

Another subject of the invention is a method for manufacturing a rotor of a rotating electrical machine as defined above.

The method may include the step of introducing longitudinally, along the axis of rotation of the rotor, at least one permanent magnet into the housing.

In the case where the rotor mass comprises several stacks of laminations stacked on top of each other, the method may first comprise the step consisting in introducing longitudinally at least one permanent magnet into the housing of each stack of laminations, then the step consisting of stacking the stacks of sheets on top of each other, with the permanent magnets in the housings.

Brief description of the drawings

[Lig 1] Figure 1 is a schematic and partial view, in cross section, of a rotating electrical machine rotor according to the invention,

[Lig 2] Figure 2 is a view similar to Figure 1 without the permanent magnets, [Lig 3] Figure 3 is a view similar to Figure 1,

[Lig 4a] Figure 4a is a view similar to Figure 2 of an alternative embodiment,

[Lig 4b] Figure 4b is a view similar to Figure 2 of an alternative embodiment,

[Line 4c] Figure 4c is a view similar to Figure 2 of an alternative embodiment,

[Lig 4d] Figure 4d is a view similar to Figure 2 of an alternative embodiment,

[Lig 5] Figure 5 is a view similar to Figure 1 of an alternative embodiment, [Lig 6] Figure 6 is a view similar to Figure 1 of an alternative embodiment. [Lig 7a] Figure 7a is a view similar to Figure 1 of an alternative embodiment. [Fig 7b] Figure 7b is a view similar to Figure 1 of another sheet of the variant of Figure 7a.

[Fig 8a] Figure 8a is a sectional view, schematic and partial, of an alternative rotor embodiment.

[Fig 8b] Figure 8b is a sectional view, schematic and partial, of a rotor embodiment variant.

[Fig 8c] Figure 8c is a sectional view, schematic and partial, of a rotor embodiment variant.

detailed description

There is illustrated in Figures 1 to 3 a rotor 30 of a rotating electrical machine according to the invention, comprising a rotor mass 33 in which are formed housings 10. Permanent magnets are inserted into each of the housings 10, so as to define poles of the rotor. This rotor is intended to be associated with a stator, not shown.

The magnets are in this example of generally rectangular shape in cross section as illustrated in the embodiments of Figures 1, 5 and 6. Each magnet has, in cross section, on the one hand, a first long side and a second long side , opposite the first, and on the other hand, a first short side and a second short side, opposite the first. Each housing 10 is delimited by two faces respectively facing the first long side and the second long side of the magnet.

The housings 10 of a pole are arranged in a first row 11 of housings further from the air gap and a second row 12 of housings closer to the air gap.

The first row 11 of housings 10 comprises three housings 10 arranged in a U, with a central housing and two lateral housings symmetrical to each other with respect to an axis of the pole P.

A length L2 of a larger rectangle inscribed in the central housing is in the example described equal to the length L1 of the largest rectangle inscribed in a lateral housing. The 'length' is measured along the axis of the row of slots. The length L3 is designated as the length of a larger rectangle inscribed in a housing of the second row. The width B of the largest rectangle inscribed in the central housing is equal to the width B of the largest rectangle inscribed in a side housing. We speak of 'width' to designate the dimension perpendicular to the length in the plane of a transverse section of the rotor mass.

The side housings of the first row 11 are provided with permanent magnets, as is the central housing. The permanent magnets of the side housings and the central housing of the first row 11 are identical to each other. In particular, they have the same size in cross-section.

Each lateral housing of the first row forms a bridge of material with the central housing, the two bridges of material each having a longitudinal axis, the two axes being parallel to each other.

In addition, the two side housings of the first row 11 include a recess 15 which extends from the side housing towards the central housing. The recess 15 is configured to project radially from the central housing by a distance Y. The recess 15 has a width X and a length Z.

Furthermore, the recess 15 has an edge which extends at least partially parallel to an edge of the central housing.

The second row 12 comprises two housings arranged in a V. They are symmetrical to each other with respect to an axis of the pole P. In the example described, all the housings of the second row 12 are provided with permanent magnets . The second row permanent magnets are identical to each other. In particular, they have the same size in cross-section. In contrast, the second row permanent magnets are a different size from the first row permanent magnets, being smaller. The width A of a slot in the second row is less than the width B of a slot in the first row.

The side housings of the first row 11 as well as the housings of the second row 12 comprise at least one abutment 16 for holding the permanent magnet intended to be received in the housing, this abutment 16 being located towards the air gap. The angular opening a3 of the second row 12 is defined. This angular opening a3 is greater than twice the sum of the angular opening al between two consecutive poles and the angular opening a2 between the first and second rows. We can write a3 > 2 (al + a2). In the example described, we have a3=1.2*2 (a1+a2). The angular openings are measured at the surface of the rotor, at the level of the air gap, for a given pole of the rotor, as shown in Figure 2.

Furthermore, the angular aperture a3 of the second row can be defined by the following relationship: a3 = k 2p/(2r), where p is the number of pairs of rotor poles which is 4 in the example described, and k the coefficient of polar opening, which is equal to 34.6%.

An angle a4 between the adjacent housings 10 of two consecutive poles is in the example described 24.8°. The two adjacent housings considered for the measurement of the angle a4 between the two consecutive poles are housings of the first row.

By way of example, with reference to FIG. 3, values of angle and angular openings are given. The side magnets of the first row 11 make between them an angle bΐ of approximately 70°. The magnets of the second row 12 form between them an angle b2 of approximately 103°.

The angular opening a3 of the second row 12 is about 13 mm. The angular opening a5 of the first row 11 is about 30 mm.

Finally, a gap D between the two recesses of the side housings of the first row 11 is approximately 15 mm.

Of course, the shapes of the housings 10 and the recesses 15 could vary without departing from the scope of the present invention. By way of example, variant embodiments have been illustrated in FIGS. 4a to 4d.

In the example of Figure 4a, the housings of the second row 12 are elongated at a point so as to reduce the distance W between the bottom of the second row and the first row.

In the example of Figure 4b, the recesses 15 of the housings of the first row 12 are shortened, not projecting radially from the central housing.

In the example of FIG. 4c, the recesses 15 of the housings of the first row 12 are on the contrary elongated, ending in a semicircle. In the example of FIG. 4d, the recesses 15 of the housings of the first row 12 are separated from the rest of the housing by a stop 17 for holding the permanent magnet.

In the embodiment of Figures 1 and 2, the side housings of the first row 11 are provided with permanent magnets, as is the central housing, these magnets being all identical.

In the variant embodiment illustrated in FIG. 5, the central housing of the first row 11 is provided with a permanent magnet smaller than the permanent magnets of the side housings, of length L4 less than the length L1 or the length L2.

As a further variant, as illustrated in FIG. 6, the central housing of the first row may be empty, being devoid of a permanent magnet.

In the variant embodiment illustrated in FIGS. 7a and 7b, certain laminations of the rotor comprise deformable tabs 19 which are each connected to one face of the corresponding housing, as illustrated in FIG. 7a, while other laminations of the stack n 'not include, as shown in Figure 7b. In the example shown, only the side housings of the first rows and the housings of the second rows have such a deformable tongue 19.

The deformable tongues 19 each extend into the corresponding housing. Each deformable tab 19 has a portion which is bent so as to be pressed against a small side of the corresponding magnet. The bendable portion of the deformable tongue 19 is bent outside the plane of the sheets, along a folding axis of the deformable tongue 19 extending in a plane parallel to the plane of the sheet.

In the examples described, the machine has a number of poles of 8. Of course, it is not beyond the scope of the present invention if this is different, being for example 6.

In a variant embodiment illustrated in FIG. 8a, the laminations of the rotor mass comprise notches 62 on the surface of the rotor mass facing the air gap.

E.

In this example, the notches are of partially elliptical shape, with a depth br, measured radially in the plane of the sheet, greater than the width ar of the notch 62, measured circumferentially in the plane of the sheet. In the example of FIG. 8a, a pole of the rotor has four notches 62 distributed symmetrically on either side of an axis of the pole.

In particular when the notches of a pole are not distributed symmetrically, the notches of the laminations of a first package of the rotor mass are angularly offset with respect to the notches of the laminations of a second package of the rotor mass.

By way of example, there is illustrated in FIG. 8b a rotor formed of two identical sheets turned over, in order to form two packets 50a, 50b of sheets each comprising two notches 62 angularly offset.

In the example of Figure 8c, the rotor comprises four packets 50a, 50b, 50c, 50d, each comprising a single notch 62 angularly offset. The notches 62 here differ in their depth.

Of course, it is not beyond the scope of the present invention if the rotor comprises a configuration different from those illustrated, for example by the number of packets, by the position of the notches or their shape or size.

Claims

1. Rotor (30) of a rotating electrical machine, comprising a rotor mass (33) comprising laminations stacked on top of each other, the rotor mass (33) comprising a plurality of housings (10), at least some of the housings, see all the housings, receiving one or more permanent magnets defining poles of the rotor, the housings of a pole being arranged in at least a first (11) and a second (12) row of housings, the first row (11) of housings comprising three housings arranged in a U, with a central housing and two lateral housings, a length (L2) of a largest rectangle inscribed in the central housing being equal to +/- 20% of the length (L1) of the largest rectangle inscribed in a lateral housing, at least one of the lateral housings, in particular the two lateral housings of the first row, comprising a recess (15) which extends from the lateral housing towards the central housing, the recess (15) being configured for radial overhang ment of the central housing.

2. Rotor according to the preceding claim, the width (B) of the largest rectangle inscribed in the central housing being equal to +/- 50% to the width (B) of the largest rectangle inscribed in a side housing.

3. Rotor according to any one of the preceding claims, in which the side housings of the first row (11) are provided with permanent magnets.

4. Rotor according to any one of the preceding claims, the central housing of the first row (11) being provided with a permanent magnet smaller than the permanent magnets of the side housings.

5. Rotor according to any one of the preceding claims, the housings of the second row (12) being arranged in a V.

6. Rotor according to any one of the preceding claims, in which an angular opening (a3) of the second row is greater than or equal to twice the sum of the angular opening (al) between two consecutive poles and the angular opening (a2) between the first and second rows.

7. Rotor according to any one of the preceding claims, in which an angular opening (a3) of the second row (12) is given by the following relationship: a3=k 2p/(2r), where p is the number of rotor pole pairs and k the polar opening coefficient, with the polar opening coefficient k which is included in the interval [22.5%; 37.5%], better in the range [25%; 35%].

8. Rotor according to any one of the preceding claims, an angle (a4) between the adjacent housings of two consecutive poles being strictly greater than 0, being in particular between 5° and 35°, better still between 12° and 30°.

9. Rotor (30) of a rotating electrical machine, comprising a rotor mass (33) comprising laminations stacked on top of each other, the rotor mass (33) comprising a plurality of housings (10), at least some of the housings, see all the housings, receiving one or more permanent magnets defining poles of the rotor, the housings of a pole being arranged in at least a first (11) and a second (12) row of housings, the first row (11) of housings comprising three housings arranged in a U, with a central housing and two lateral housings, a length (L2) of a largest rectangle inscribed in the central housing being equal to +/- 20% of the length (L1) of the largest rectangle inscribed in a lateral housing, at least one of the lateral housings, in particular the two lateral housings of the first row, comprising a recess (15) which extends from the lateral housing towards the central housing, each lateral housing of the first row cleaning nt with the central housing a material bridge, the two material bridges each having a longitudinal axis, the two axes being parallel to each other.

10. Rotor according to any one of the preceding claims, a width (X) of the recess (15) being between 0 mm and twice the width (B) of the central housing.

11. Rotor according to any one of the preceding claims, a radial dimension (W) between the bottom of the second row and the first row being between once the width B of the central housing and three times the latter.

12. Rotor according to any one of the preceding claims, the recess having an edge which extends at least partially parallel to an edge of the central housing.

13. Rotor according to any one of the preceding claims, at least one housing comprising at least one abutment (17) for holding the permanent magnet intended to be received in the housing.

14. Rotor according to any one of the preceding claims, being devoid of circulation of cooling fluid in the housings.

15. Rotating electrical machine, comprising a stator and a rotor (30) as defined according to any one of the preceding claims.