stator of a rotating electric machine

Abstract

The present invention relates to a stator (2) of a rotary electric machine (1), the stator comprising a stator mass block (25) comprising teeth (23) and grooves (21) between the teeth (23), each of the grooves being completely closed on the side where the air gap is located, and an electrical conductor (22) being accommodated in the groove, the electrical conductor forming a fractional slot winding, for which the ratio q defined by q = Ne / (2pm) is written in the form of an irreducible fraction z / n, z and n being two non-zero integers, n being different from 1, where Ne is the number of stator grooves, m is the number of winding phases, and p is the number of stator pole pairs.

Description

Technical Field

[0001] This invention claims priority to French application 1902069, filed on February 28, 2019, the disclosure of which (text, drawings and claims) is incorporated herein by reference.

[0002] This invention relates to rotary electric machines, and more particularly to the stator of such machines.

[0003] This invention relates more specifically to AC synchronous or asynchronous motors. More particularly, it relates to traction or propulsion mechanisms for battery electric vehicles and / or hybrid electric vehicle-plug-in hybrid electric vehicles, such as passenger cars, mini-trucks, trucks, or buses. The invention also applies to rotating motors for industrial and / or production applications (especially marine or wind power applications). Background Technology

[0004] Motors used in motor vehicle applications typically have several grooves per pole per phase and open or semi-open stator grooves.

[0005] In patent applications US2003 / 0214196 and US2007 / 0018525, and in patent US7348705, the recesses are semi-open and accommodate U-shaped electrical conductors distributed across four layers and between two separate sets of coils, each set consisting of two layers. The conductors of the two different sets of coils are not electrically connected together in the stator. The phase-to-phase connection is implemented in a terminal box and outside the stator. In application US2007 / 0018525, the stator has a number of recesses per pole per fraction of phase.

[0006] In patent application CN205583868, the stator has a plurality of grooves per pole per fraction of phase, the grooves being completely closed on the side where the air gap is located and closed on the opposite side by an added magnetic yoke. However, the stator has a concentrated winding, the concentrated winding being wound on the teeth.

[0007] In patent application US2014 / 319953, the groove of the stator is not closed.

[0008] Additionally, in known stators, the stator yoke is provided with fully or partially open grooves facing the air gap to allow the introduction of conductors from the winding. Typically, the partially open grooves receive randomly arranged conductors with circular cross-sections, while the fully open grooves accommodate conductors arranged in rows with rectangular cross-sections.

[0009] A stator is also known in which the grooves are sealed by non-magnetic or semi-magnetic gaskets. However, these gaskets may detach and interfere with the operation of the machine.

[0010] Patent application US2010 / 001609 aims to provide a stator in which the slots are closed and receive U-shaped electrical conductors having a rectangular cross-section, each of which is connected to a conductor in an adjacent slot to form a series of wave windings. The windings are not fractional slot windings.

[0011] Patent application FR3019947 describes a stator including a crown of teeth, the crown comprising teeth interconnected by material bridges, the teeth defining recesses between each other for receiving coils, the recesses opening radially outward. The openings of the recesses are closed by magnetic yokes added to the crown of teeth.

[0012] There is a need for stators in rotating electrical machines that are easy to assemble, allowing for efficient filling of grooves while ensuring satisfactory electromagnetic performance. There is also a need for further improvements to the stator of the machine, and in particular for reducing torque ripple, vibration, and electromagnetic noise. Summary of the Invention

[0013] stator

[0014] This invention aims to meet this requirement, and according to one aspect of the invention, this requirement is achieved by a stator of a rotating electric motor, the stator comprising a stator mass block including teeth and grooves between the teeth, each of the grooves being at least partially closed (especially completely closed) on the side where the air gap is located, an electrical conductor being accommodated in the groove, the electrical conductor forming a winding, especially a single (unique) fractional slot winding, for which the ratio q defined by q = Ne / (2pm) is written as an irreducible fraction z / n, where z and n are two non-zero integers, n being different from 1, where Ne is the number of stator grooves, m is the number of winding phases, and p is the number of stator pole pairs. At least a portion (or even most of the electrical conductor) of the electrical conductor takes the form of pins, especially U-shaped or I-shaped pins.

[0015] Independently or in combination with the foregoing, the present invention particularly aims to provide a stator for a rotating electric motor, the stator comprising a stator mass block including teeth and grooves between the teeth, each of the grooves being completely closed on the side where the air gap is located, and an electrical conductor being accommodated in the groove, the electrical conductor forming a fractional-slot winding, for which the ratio q defined by q = Ne / (2pm) is written as an irreducible fraction z / n, z and n being two non-zero integers, n being different from 1, where Ne is the number of stator grooves, m is the number of winding phases, and p is the number of stator pole pairs. The stator may include one or more of the features mentioned above or below. In particular, at least a portion (or even most of the electrical conductors) may take the form of pins, especially U-shaped or I-shaped, and extend axially in the grooves.

[0016] Independently or in combination with the foregoing, the present invention also aims to provide a stator for a rotating electric motor, the stator comprising a stator mass block including teeth and grooves between the teeth, each of the grooves being at least partially closed on the side where the air gap is located, an electrical conductor being accommodated in the groove and distributed on at least two layers (especially on only two layers), the electrical conductor forming a single fractional-slot winding for which the ratio q, defined by q = Ne / (2pm), is written as an irreducible fraction z / n, where z and n are two non-zero integers, n being different from 1, where Ne is the number of stator grooves, m is the number of winding phases, and p is the number of stator pole pairs. The stator may include one or more of the features mentioned above or below. In particular, at least a portion (or even a majority of the electrical conductors) may take the form of pins, especially U-shaped or I-shaped, and extend axially within the grooves.

[0017] Fractional slot winding (Bobinage fractionnaire)

[0018] The winding consists of several (m) phases that are space-displaced to generate a rotating field when powered by a multiphase current system.

[0019] The electrical conductors may form a single winding. A “single winding” is understood to mean that the electrical conductors are electrically connected together in the stator, and the connection between phases is implemented in the stator, rather than outside the stator (e.g., in a terminal box).

[0020] The electrical conductors may form distributed windings. The windings are not concentrated on the teeth or wound with wire.

[0021] In this invention, the winding is a fractional-slot winding. The winding can be a fractional-slot winding.

[0022] For fractional slot windings, the number of slots per pole per phase is a fraction, that is, the ratio q defined by q = Ne / (2pm) is written as an irreducible fraction z / n, where z and n are two non-zero integers, and n is different from 1. Here, Ne is the number of stator slots, m is the number of winding phases, and p is the number of stator pole pairs.

[0023] In the embodiments, q can be strictly greater than 1.5, and more preferably greater than or equal to 2.25, for example, especially equal to 5 / 2 or 7 / 2. This reduces torque harmonics.

[0024] The number of stator grooves can be between 18 and 96, more preferably between 30 and 84, for example, 18, 24, 27, 30, 36, 42, 45, 48, 54, 60, 63, 72, 81, 92, 96, more preferably 60 or 63. The number of stator poles can be between 2 and 24, or even between 4 and 12, for example, 6 or 8.

[0025] The combination of stator groove number / pole number can be selected from the following non-limiting list of combinations: 30 / 4, 42 / 4, 45 / 6, 63 / 6, 60 / 8, 84 / 8.

[0026] In this embodiment, the combination of the number of stator grooves / number of poles is 60 / 8. In this case, q = 60 / (2*4*3) = 5 / 2.

[0027] In the embodiment, the combination of the number of stator grooves / number of pole pairs is 63 / 6, or in this case, q = 63 / (2*3*3) = 7 / 2.

[0028] More broadly, for three-phase windings, the combination between the number of stator slots Ne and the number of pole pairs p can be one of the combinations marked in Table 1.

[0029] A higher number of grooves per pole per phase allows for better harmonic filtering.

[0030] [Table 1]

[0031]

[0032] Table 1

[0033] In this case, the number of phases is three, but when the number of phases is not the same, it does not depart from the scope of the invention; the number of phases is, for example, two (the machine thus includes a two-phase winding), or, for example, 5, 6, or 9. Preferably, the winding is multiphase.

[0034] The advantages of fractional slot windings, which are optionally associated with enclosed slots, will now be explained.

[0035] Torque fluctuations and magnetic forces depend on the induction spectrum in the air gap and constitute the main sources of electromagnetic noise. This noise manifests on the one hand as torque fluctuations interacting with the transmission system, and on the other hand as magnetic forces applied to the stator of the machine, which can excite the machine's inherent modes according to its amplitude and frequency, thus causing the machine to resonate.

[0036] The harmonics causing these magnetic force and torque fluctuations are due to spatial harmonics in the groove. These harmonics are caused by variations in the air gap permeability, which depends on the opening of the groove and the discrete distribution of the magnetomotive force.

[0037] In the case of machines with open or semi-open grooves, the permeability spectrum is rich in harmonics, which increases the harmonic rate of the magnetic force; since the stator yoke is less rigid as the opening of the groove is larger, the stator yoke can therefore suffer more from resonance problems.

[0038] In machines with integer step sizes, to reduce harmonics in the air gap field, a relatively high (e.g., greater than 3) number of grooves per pole per phase is typically used, along with a shortened opening step size for the coils. To reduce groove harmonics caused by the distribution of the windings, vrillage of the machine's stator or rotor can be implemented. However, this method adds additional manufacturing steps.

[0039] It is understood that the fractional slot winding can reduce the harmonic content of the magnetomotive force in the air gap, thereby reducing torque ripple and the amplitude of radial and tangential magnetic pressure.

[0040] For example, Table 2 below shows a comparison of harmonic rates between a machine with 48 grooves, 8 poles, and a number of grooves per pole per integer phase (with and without shortening) and a machine with 60 grooves, 8 poles, and a number of grooves per pole per fractional phase, which shows the advantages of fractional steps.

[0041] [Table 2]

[0042] machine Harmonic frequency (pu) The integer q without shortening 1 The integer q when shortened 0.76 fraction q 0.15

[0043] Table 2: Harmonic rates (in pu) between integer and fractional q

[0044] Table 3 below shows a comparison of torque ripple (in %) between a machine with 48 slots in 8 poles, with a number of slots per pole per integer phase (with both straight and twisted rotors), a machine with 72 slots in 6 poles, with a number of slots per pole per integer phase (with both straight and twisted rotors), and a machine with 63 slots in 6 poles, with a number of slots per pole per fractional phase (with a straight rotor). It is understood that the advantage of fractional-slot windings is that they reduce torque ripple rate without relying on rotor twisting.

[0045] [Table 3]

[0046]

[0047]

[0048] Table 3: Torque Fluctuation (%)

[0049] The series arrangement of electrical conductors can be implemented as a so-called wave winding or a so-called lap winding.

[0050] "Bobinage ondulé" is understood as a type of winding in which electrical conductors of the same pole are electrically connected to each other, such that, for a winding track, the current of the phase flows in only one direction among the electrical conductors rotating about the axis of rotation of the machine. For the winding track, when viewed perpendicular to the axis of rotation of the machine, electrical conductors of the same pole do not overlap.

[0051] "Bobinage imbriqué" is understood as a type of winding in which conductors of the same phase and same pole are electrically connected to each other, such that the current of said phase flows alternately in one direction and then in another among conductors rotating about the axis of rotation of the machine. For the winding track, conductors of the same pole overlap when viewed perpendicular to the axis of rotation of the machine.

[0052] The winding may include only one winding track or multiple winding tracks. Current of the same phase flows through the winding track in the "electrical conductors". A "winding track" is understood to be all the electrical conductors of the machine through which the same current of the same phase flows. These electrical conductors may be connected in series, in parallel, or in a series-parallel configuration. In the case of only one track, the electrical conductors are connected in series. In the case of multiple tracks, the electrical conductors of each track are connected in series, and the tracks are connected in parallel.

[0053] Electrical conductor

[0054] Current of the same phase flows through a winding track in an “electric conductor”.

[0055] In each recess, one or more layers may exist. A "layer" is understood as a series conductor belonging to the same phase arranged in the same recess. Each layer in the recess contains an electrical conductor of the same phase. Typically, the stator's electrical conductors may be distributed in one or more layers (e.g., two, three, or four layers). When the electrical conductors are distributed on only one layer, each recess accommodates only the electrical conductor of the same phase.

[0056] In this invention, the electrical conductors can be distributed across at least two layers (especially only two layers). In this case, one or more grooves can accommodate electrical conductors of two different phases. The same applies to windings with shortened step lengths.

[0057] In this embodiment, the winding may not comprise more than two layers. In particular, the winding may not have four layers.

[0058] At least one first electrical conductor disposed in the first groove may be electrically connected to a second electrical conductor disposed in the second groove at the outlet of the groove.

[0059] "Electrical connection" is understood to mean any type of electrical connection, which is implemented, in particular, by welding or mechanical clamping using various possible welding methods, in particular laser, induction, friction, ultrasonic, vibration or brazing, and the mechanical clamping, in particular, by, for example, inlaying, screwing or riveting.

[0060] Preferably, the first groove and the second groove are not connected.

[0061] The first and second electrical conductors are electrically connected at the exits of the first and second grooves, that is, exactly after the conductors exit the two grooves, the electrical connection is formed on the conductors and at the axial end of the stator mass block. The electrical connection can be implemented in a plane perpendicular to the rotation axis of the machine. The plane of the electrical connection can be less than 60 mm away from the stator mass block, more preferably less than 40 mm, for example, about 27 mm or 38 mm.

[0062] Each of the majority of the electrical conductors accommodated in the first groove may be electrically connected to a second electrical conductor, respectively accommodated in the second groove, at the outlet of the groove. At least one groove (more preferably a majority of the groove, or even more than half of the groove, more preferably two-thirds of the groove, or even all of the groove) may include a first electrical conductor, each of the first electrical conductors being electrically connected to a second electrical conductor, respectively accommodated in the second groove, at the outlet of the groove.

[0063] In one embodiment, all electrical conductors with free ends located at the same circumferential position around the axis of rotation of the machine are electrically connected together, regardless of their radial position.

[0064] Each of the first and second electrical conductors may include a sloping portion. The sloping portion may extend in a circumferential direction about the axis of rotation of the machine. The two sloping portions may be configured to approach each other from one side, and thus enable the electrical connection.

[0065] An electrical conductor may include two inclined portions (one at each of its two ends). The two inclined portions of the same electrical conductor may extend in opposite directions. The two inclined portions may be symmetrical about one to the other.

[0066] The majority of the electrical conductor may include one or more sloping portions as described above.

[0067] The electrical conductors may be distributed in the grooves. "Distributed" is understood to mean that each of the transmitting and returning electrical conductors is housed in a different and non-contiguous groove. At least one of the electrical conductors may pass sequentially from two non-contiguous grooves.

[0068] The electrical conductors may be arranged in rows in the groove. "Row" is understood to mean that the electrical conductors are arranged in an orderly manner rather than randomly in the groove. The electrical conductors are stacked in the groove in a non-random manner, for example, arranged in one or more rows of electrical conductors aligned particularly along the radial and / or circumferential directions.

[0069] The electrical conductor may have a generally rectangular cross-section, particularly with rounded corners. The circumferential dimension of the electrical conductor may substantially correspond to the width of the groove. Thus, the groove may contain only one electrical conductor within its width. The groove width is measured in the circumferential dimension about the axis of rotation of the machine.

[0070] The electrical conductors can be adjacent to each other through their own wide sides (also called flat surfaces).

[0071] Optimization of the stacking allows for the arrangement of a greater number of electrical conductors in the grooves, and thus enables a stator with greater power at a constant volume.

[0072] Each groove may include 2 to 36 electrical conductors, particularly 2 to 24 electrical conductors, more preferably 2 to 12 electrical conductors. Each groove may include two to eight electrical conductors, particularly two to four electrical conductors, for example, two or four electrical conductors. In an embodiment, each groove includes two electrical conductors. In another embodiment, each groove includes four electrical conductors.

[0073] Epingles

[0074] The electrical conductor may at least (or even most of the electrical conductor) take the form of a U-shaped or I-shaped pin. The pin may be U-shaped or straight and I-shaped.

[0075] The pin-shaped, flat electrical conductors increase the groove fill rate while making the machine more compact. The higher fill rate improves heat exchange between the electrical conductors and the stator mass block, which reduces the temperature of the electrical conductors inside the grooves.

[0076] Furthermore, the stator manufacturing is facilitated by the presence of pin-shaped conductors. Additionally, the winding with the pins can be easily modified simply by changing the connection between the pins at the coil head position. Finally, the pins do not necessarily have open grooves, but can have closed grooves that can hold the pin in place, thus eliminating the need for inserting stator spacers.

[0077] In this case, there is no need to add a magnetic yoke, which improves the mechanical properties and thermal conductivity of the stator.

[0078] In a variation, the electrical conductor may comprise a round wire. In an embodiment, the stator may comprise a magnetic hoop as defined below and an electrical conductor in the form of a round wire. These electrical conductors may be inserted into the groove from the air gap side before the hoop is placed in place.

[0079] The electrical conductor (or even most of the electrical conductor) extends axially within the groove. The electrical conductor may be introduced into the corresponding groove from one or both of the two axial ends of the machine.

[0080] The I-shaped electrical conductor has two axial ends, each of which is positioned at one of the axial ends of the stator. The electrical conductor passes through a single groove and can be welded to two other electrical conductors at each of its axial ends at the axial end position of the stator.

[0081] The U-shaped electrical conductor has two axial ends, each located at one of the axial ends of the stator. The conductor passes through two different recesses and can be welded to two other electrical conductors at each of its axial ends at a location on the same axial side of the stator. The bottom of the U-shape is arranged on the other axial side of the stator.

[0082] Due to its U-shaped pin form, the electrical conductor may include a first leg and a second leg, which extend axially in a first groove A and a second groove R, respectively. The opening of the electrical conductor may also be discussed. The first groove A and the second groove R are separated by a number of teeth, Nd. This refers to the number of teeth between the incoming and outgoing grooves of the same electrical conductor. The number of teeth Nd may be strictly greater than 5, for example, greater than or equal to 6. This number may be, for example, 6, 7, and / or 8, or 9, 10, and / or 11.

[0083] For all the stator conductors that take the form of U-shaped pins, the number of teeth Nd can be the same. The step size of the conductors can also be discussed with respect to the number of teeth Nd. When the step size is the same for all the stator conductors that take the form of U-shaped pins, the manufacture of the U-shaped pins is facilitated, and the steps of positioning (especially inserting) these U-shaped pins in the stator mass block are simplified. Advantageously, this configuration can improve the smoothness of the field in the air gap and reduce the harmonics of the stator.

[0084] Stock line (Brins)

[0085] In embodiments, each electrical conductor may include one or more strands. A "strand" is understood as the most basic unit used for conducting electricity. A strand may have a circular cross-section (therefore discussed as a "wire") or be flat. Flat strands may, for example, be formed into pins in the shape of a U or I. Each strand is coated with an insulating enamel.

[0086] Each groove may include multiple conductors and / or multiple strands of wire, which minimizes losses caused by induced current (or AC Joule losses), which vary with the square of the supply frequency, and is particularly advantageous at higher operating speeds. This results in better efficiency at high speeds.

[0087] The presence of the closed groove allows for a reduction in the leakage flux observed from the conductor, which in turn reduces losses caused by Foucault current in the strands.

[0088] As mentioned above, in an embodiment, each electrical conductor may include one or more pins, each of which forms a strand. In this case, all strands of the same electrical conductor may be electrically connected to each other at the outlet of the groove. The electrically connected strands are arranged to be in a short-circuit state. The number of strands electrically connected together may be greater than or equal to 2, for example, between 2 and 12, such as 3, 4, 6, or 8 strands.

[0089] Multiple strands can form the same electrical conductor. The same current of the same phase flows through all the strands of the same electrical conductor. All the strands of the same electrical conductor can be electrically connected to each other, particularly at the outlet of the groove. All the strands of the same electrical conductor can be electrically connected to each other, particularly at each of their two axial ends, at the outlet of the groove. The strands can be electrically connected in parallel.

[0090] All strands of all electrical conductors, whose free ends are located at the same circumferential position around the axis of rotation of the machine, can be electrically connected to each other regardless of their radial position.

[0091] In one embodiment, each electrical conductor comprises only one strand. In another embodiment, each electrical conductor comprises three strands.

[0092] In cases where the groove comprises two electrical conductors, the groove can thus accommodate two strands (or, in a variation, six strands), which are distributed, for example, between the two electrical conductors.

[0093] In a variation, the groove includes four electrical conductors. Each conductor may include two strands. The groove thus accommodates eight strands distributed among the four electrical conductors.

[0094] The strands can be positioned within the grooves such that their circumferential dimension about the machine's axis of rotation is greater than their radial dimension. This configuration reduces losses caused by the Foucault current in the strands.

[0095] The width of the strand can be between 1 mm and 5 mm, for example, approximately 2.5 mm or 3 mm. The width of the strand is defined as its dimension along its circumferential direction about the axis of rotation of the machine.

[0096] The strand may have a height between 1 mm and 4 mm, for example, approximately 1.6 mm or 1.8 mm. The height of the strand is defined as its thickness in the radial dimension.

[0097] The ratio of line width to line height can be between 1 and 2.5, more preferably between 1.2 and 2, or even between 1.4 and 1.8, such as 1.56 or 1.66.

[0098] In another embodiment, the strand may have a height between 2 mm and 8 mm, for example, approximately 4.75 mm. The height of the strand is defined as its thickness in the radial dimension. The ratio of strand width to strand height may be less than 1, for example, between 0.9 and 0.2, or even between 0.8 and 0.3, for example, approximately 0.5 to 0.6.

[0099] The electrical conductor may be made of copper or aluminum.

[0100] insulation

[0101] The electrical conductor is electrically insulated from the outside by an insulating coating (especially a glaze). The electrical conductor can be separated from the wall of the groove by an insulator (especially by at least one insulating sheet). This sheet-like insulator allows for better insulation of the electrical conductor relative to the stator mass block. The use of a closed groove allows for improved retention of the insulator within the groove around the electrical conductor.

[0102] Partially enclosed groove or completely enclosed groove

[0103] The groove can be at least partially closed. The partially closed groove can have an opening at the air gap location, which can, for example, serve to accommodate the placement of an electrical conductor for filling the groove. The partially closed groove is particularly located between two teeth, each of which includes a pole shoe at its free end location, the pole shoe at least partially closing the groove.

[0104] In a variant, the groove may be completely closed. A “completely closed groove” is understood to be a groove that does not open radially toward the air gap.

[0105] The groove can be closed by a magnetic hoop on the side where the air gap is located. The hoop can be added to the tooth on the side where the air gap is located. The magnetic hoop can preferably have the same magnetic permeability as the stator. The magnetic hoop can be made, in particular, of the same material as the stator mass block. The magnetic hoop can be generally annular and arranged in the air gap. The magnetic hoop forms a material bridge between the teeth, which closes the groove on the side where the air gap is located. These material bridges are not integrally formed with the teeth defining the groove. The magnetic hoop can be made from a single part, especially over the entire circumference of the stator. The magnetic hoop can be formed by a stack of rolled metal sheets.

[0106] The magnetic hoop may have at least one locally narrowed portion, which is formed by at least one notch. For each material bridge closing the groove, the hoop may particularly include at least one notch, which may be arranged in front of each of the grooves.

[0107] When using a hoop, this allows the use of round wire conductors.

[0108] In the variant, the stator is not provided with a hoop added to close the groove.

[0109] In one embodiment, at least one groove (or even each groove) may be continuously closed on the air gap side by a material bridge, the material bridge being integrally formed with the teeth defining the groove. All grooves may be closed on the air gap side by material bridges, the material bridges closing the grooves. The material bridges may be integrally formed with the teeth defining the grooves. The stator mass block thus does not have a cut between the teeth and the material bridges closing the grooves, and the grooves are thus continuously closed on the air gap side by material bridges, the material bridges being integrally formed with the teeth defining the grooves.

[0110] Furthermore, the groove can be closed on the side opposite to the air gap by a magnetic yoke, which is added to or integrally formed with the tooth. The groove thus does not open radially outward. The stator mass block may not have a cut between the tooth and the magnetic yoke.

[0111] In this embodiment, each of the grooves has a continuously closed profile. "Continuously closed" is understood to mean that the grooves have a continuously closed profile when viewed in a cross-section perpendicular to the rotation axis of the machine. The grooves can be completely surrounded without encountering cuts in the stator mass block.

[0112] The presence of the enclosed recess improves the magnetic field quality of the motor's air gap by minimizing harmonic content, losses caused by Foucault current in the conductor, leakage flux in the recess, magnetic field fluctuations in the air gap, and heating of the machine. The enclosed recess can have a closed cylindrical air gap and can reduce leakage flux in the recess, which reduces AC losses in the stator windings. Therefore, the battery life is extended because the machine's efficiency is improved due to reduced AC losses.

[0113] Furthermore, the presence of these enclosed grooves improves the mechanical stiffness of the stator by mechanically reinforcing it and by reducing vibration. This can, in particular, achieve a resonant frequency far removed from the deformation mode corresponding to 2p, where p is the number of stator pole pairs. The reduction in vibration can contribute to quieter machine operation, which can be especially advantageous when the stator is used in conjunction with a gearbox system.

[0114] In addition, since the groove is closed, the parasitic capacitance between the stator winding and the rotor can be reduced, which reduces leakage current and makes it possible to avoid using shaft current drain rings or drain brushes.

[0115] The stator mass block can be made of a stack of magnetic metal plates, with the grooves formed by cutting the metal plates. Alternatively, the stator mass block can be made by tailoring within a sintered or bonded magnetic powder mass block. The closure of the grooves on the air gap side is achieved by a material bridge, which is integrally formed with the remainder of the metal plate or with the remainder of the block forming the stator mass block.

[0116] The stator according to the invention does not have magnetic gaskets added to seal the grooves. This eliminates the risk of accidental detachment of these gaskets.

[0117] Material Bridge

[0118] The stator mass block may include teeth disposed between the grooves, the teeth being connected to each other by material bridges on the air gap side. Thus, each groove is closed on the air gap side by a material bridge that connects two consecutive teeth of the stator mass block to each other. Each of the material bridges connects two adjacent teeth at its bottom on the air gap side and defines the bottom of the groove between these teeth on the air gap side.

[0119] The material bridge is integrally formed with the adjacent teeth.

[0120] Two consecutive teeth are connected on opposite sides by a magnetic yoke. The magnetic yoke can be integrally formed with the teeth. The stator may therefore not have a magnetic yoke added to the tooth crown.

[0121] As mentioned above, the absence of the opening of the groove facing the air gap avoids electromagnetic interference (especially due to the increase of "magnetic" air gaps caused by flux stripes), higher iron losses at the rotor surface, or pulsating torque, radial force, and AC Joule losses for the same reason. The electromagnetic performance of the machine is thus improved.

[0122] The material bridge can be implemented to achieve magnetic saturation during machine operation. This restricts the flow of magnetic flux from one groove to another without preventing the flow of magnetic flux from the rotor toward the stator.

[0123] Preferably, the material bridge is non-deformable. This increases the stiffness of the stator and improves the lifespan of the motor.

[0124] The minimum width of the material bridge is, for example, between 0.2 and 0.5 mm. This minimum width can be, for example, approximately 0.35 mm.

[0125] The width of the material bridge can be on the same order of magnitude as the thickness of the metal plate.

[0126] For example, the stator mass block is in the form of stacked metal plates and has teeth that are connected to each other by material bridges at their bottoms on the side where the air gap is located.

[0127] The material bridge is integrally formed with the tooth.

[0128] Notch (rainure)

[0129] Each of the material bridges may have at least one local narrowing, which is formed by at least one notch. To achieve saturation, the cross section of the material bridge available for magnetic flux to pass through may be locally reduced, for example, by providing a notch.

[0130] Preferably, the notch opens toward the groove.

[0131] The groove has at least one laterally oriented mating surface (preferably at least two mating surfaces) at its bottom on the side where the material bridge is located, and the bottom of the notch is recessed relative to one or more mating surfaces. The one or more mating surfaces may be oriented at an angle relative to the radial axis of the corresponding groove, or oriented perpendicular to that axis. The notch forms a ramp interruption relative to the one or more mating surfaces. Preferably, an electrical conductor having a generally rectangular cross-section and inserted into the corresponding groove preferably rests against the mating surface and is recessed relative to the bottom of the notch. Preferably, the electrical conductor is not in contact with the notch. Preferably, the one or more mating surfaces are planar. Except for the notch, the bottom of the groove may be flat. By allowing the coil to be taken to fit flatly against the bottom of the groove, this allows the electrical conductor with a rectangular cross-section to well fill the groove.

[0132] The notch at the bottom of the groove preferably forms a gap between the material bridge and the corresponding electrical conductor.

[0133] The material bridge may include at least two notches as described above, for example, two notches per groove.

[0134] The one or more notches may be centered relative to one or more grooves, or conversely, misaligned relative to the plane of symmetry of the one or more grooves.

[0135] Preferably, each of the one or more notches has a curved profile (especially a generally semi-circular cross-section) in a plane perpendicular to the axis of the stator. The bottom of the notch may be arc-shaped or have any other suitable shape (e.g., semi-elliptical or wavy).

[0136] The inner surface of the stator is preferably cylindrical.

[0137] groove (Encoches)

[0138] At least one groove (preferably all grooves) may have a generally rectangular cross-section.

[0139] At least one groove (preferably all grooves) may include radial edges with ribs, particularly each of the radial edges having one rib. The ribs enable improved retention of the electrical conductor within the groove. Furthermore, the ribs enable minimization of AC Joule losses.

[0140] The ribs may extend parallel to the rotation axis of the machine.

[0141] The ribs may be positioned in the middle portion of the radial edges, for example, midway between the bottom of the groove and the material bridge that closes the groove. In a variation, at least one groove (preferably all grooves) may include radial edges, each of which has multiple (e.g., two or three) ribs. This can be particularly useful when the grooves are used to receive three, four, six, or eight electrical conductors. The grooves may include ribs located between each layer of electrical conductors.

[0142] In the variant, the radial edge is straight and does not have ribs.

[0143] At least one groove may be parallel to each other at opposite radial edges; more preferably, all grooves are parallel to each other at their radial edges. Preferably, the groove width is substantially constant over the entire height of the groove. This results in a better groove fill rate.

[0144] In the variant, the radial edges of the grooves are not parallel to each other.

[0145] At least one groove (preferably all grooves) may have a straight, arc-shaped, or other shaped bottom. And the bottom of the at least one groove is the bottom of the groove located on the side where the magnetic yoke is located, opposite to the material bridge and the air gap.

[0146] The groove length of at least one groove (preferably all grooves) may have a ratio of 2 to 6 (preferably 3 to 4) to the groove width. The groove width corresponds to the dimension along the circumferential direction measured about the axis of rotation of the machine, and the groove length corresponds to the dimension along the radial direction.

[0147] The stator may include a sensor for measuring the temperature of the electrical conductor, the sensor being disposed in the recess, for example, a thermocouple. The sensor may be at least partially housed in a notch of a material bridge that closes the recess. The sensor may, for example, be housed in the space between the conductor closest to the material bridge and the material bridge.

[0148] The grooves are configured to allow cooling fluid to pass through. Some or all of the grooves may accommodate flow channels for the cooling fluid, or the cooling fluid may flow directly through the grooves. The cooling fluid may flow in the bottom of the grooves and / or toward the material bridge and / or between the electrical conductors (e.g., between two layers of electrical conductors). The cooling fluid may be a gas (e.g., air) or a liquid (e.g., water or oil).

[0149] At least one tooth (preferably all teeth) may be generally trapezoidal in cross-section. At least one tooth (preferably all teeth) may have an edge that diverges away from the axis of rotation of the machine.

[0150] The stator mass block can be made of stacked metal plates. The teeth are connected to each other by material bridges and to each other on opposite sides by magnetic yokes. The closed grooves can be implemented entirely by cutting in the metal plates. Each metal plate in the stack can be monolithic.

[0151] Each metal plate is cut from, for example, a sheet of magnets or a sheet containing magnets (e.g., steel with a thickness of 0.1 to 1.5 mm). The metal plates may be coated with an electrically insulating varnish on their opposite sides before being assembled into the stack. Electrical insulation may also be obtained by heat treating the metal plates if necessary.

[0152] In a variant, the stator mass block may be manufactured based on compacted or sintered magnetic powder.

[0153] Machines and rotors

[0154] The present invention also aims to provide a rotating electric motor (e.g., a synchronous motor or synchronous generator) comprising a stator as defined above. The machine may be synchronous or asynchronous. The machine may be reluctance-based. The machine may constitute a synchronous motor.

[0155] The maximum rotational speed of the machine can be higher, for example, greater than 10,000 tr / min, more preferably greater than 12,000 tr / min, for example, about 14,000 to 15,000 tr / min, or even 20,000 tr / min or 25,000 tr / min. The maximum rotational speed of the machine can be less than 100,000 tr / min, or even less than 60,000 tr / min, more even less than 40,000 tr / min, more preferably less than 30,000 tr / min.

[0156] The rotating electric motor may include a rotor. The rotor may be of the permanent magnet type, with surface magnets or embedded magnets. The rotor may be flux-concentrated. The rotor may include one or more magnet layers arranged in an I-shape, U-shape, or V-shape. In variations, the rotor may involve a wound rotor or a squirrel-cage rotor, or a variable reluctance rotor.

[0157] The diameter of the rotor may be less than 400 mm, more preferably less than 300 mm, and greater than 50 mm, more preferably greater than 70 mm, for example, between 100 and 200 mm.

[0158] The rotor may include a rotor mass extending along a rotation axis and arranged around a shaft. The shaft may include torque transmission components for driving the rotor mass to rotate.

[0159] The rotor can be cantilevered or non-cantilevered.

[0160] The machine can be inserted separately into the housing or into the gearbox housing. In the latter case, the machine is inserted into the housing that also houses the gearbox.

[0161] Manufacturing method

[0162] Independently or in combination with the foregoing, the present invention also aims to provide a method for manufacturing a stator (especially a stator as defined above) for a rotary electric machine, wherein electrical conductors are arranged in grooves of a stator mass block of the stator by introducing electrical conductors from one or both of the two axial ends of the stator into corresponding grooves.

[0163] The same U-shaped electrical conductor can be arranged in two discontinuous grooves in the stator mass block of the stator. In the case of a U-shaped conductor, the conductor can be welded to two other electrical conductors on the same side of the machine.

[0164] Two I-shaped electrical conductors can be joined together before being introduced into two discontinuous grooves in the stator mass block of the stator. In the case of I-shaped conductors, the conductors can be welded to two other electrical conductors on two opposite sides of the machine.

[0165] In this invention, all electrical conductors with free ends located at the same circumferential position around the axis of rotation of the machine can be electrically connected together regardless of their radial position. Attached Figure Description

[0166] The invention will be better understood by reading the detailed description and accompanying drawings of non-limiting embodiments thereof, in which:

[0167] - Figure 1 This is a schematic and partial perspective view of a stator according to an embodiment of the present invention.

[0168] - Figure 2 yes Figure 1 A schematic and partial perspective view of the stator.

[0169] - Figure 3 yes Figure 1 A magnified perspective view of the stator details.

[0170] - Figure 4 The stator according to the invention is shown schematically and partially in a cross-sectional view.

[0171] - Figure 5 The stator mass block of the stator according to the invention is schematically and partially shown in a cross-sectional view.

[0172] - Figure 6 The variation of the radial air gap field (in Tesla) with angular position (in °) is shown.

[0173] - Figure 7 It is a perspective view that implements a variation.

[0174] - Figure 8 yes Figure 5 A magnified perspective view of the stator details.

[0175] - Figure 9 A schematic and partial view is shown in a cross-sectional view. Figure 7 The stator.

[0176] - Figure 10 A variant of the implementation is schematically and partially shown in a cross-sectional view. Detailed Implementation

[0177] Figures 1 to 5The stator 2 of a rotary motor 1 is shown, which also includes a rotor (not shown). In the context of a synchronous motor, the stator is capable of generating a rotating magnetic field to drive the rotor to rotate, and in the case of an AC motor, the rotation of the rotor induces an electromotive force in the electrical conductors of the stator.

[0178] The examples shown below are illustrative and do not necessarily follow the dimensions associated with different constituent elements.

[0179] The stator 2 includes an electrical conductor 22 arranged in a groove 21 between the teeth 23 of the stator mass block 25. The groove 21 is closed.

[0180] The groove 21 is closed on the side where the air gap is located by a material bridge 27, each of which connects two consecutive teeth of the stator mass block 25, and is closed on the opposite side by a magnetic yoke 29. The magnetic yoke and the teeth 23 are integrally formed. If necessary, the magnetic yoke 29 may be traversed by longitudinal ribs 31 having a semi-circular cross-section, which serve as conduits for coolant flow.

[0181] Most of the electrical conductor 22 is in the form of a pin (such as a U-shaped or I-shaped pin) and extends axially within the groove. The first electrical conductor, received in the first groove, and the second electrical conductor, received in the second groove, are electrically connected at the outlet of the groove.

[0182] The first groove and the second groove are not connected. In the example shown, the first groove and the second groove are separated by seven other grooves. In variations, the first groove and the second groove are separated by, for example, 3, 4, 5, 6, 8, 9, 10, or 11 other grooves.

[0183] In particular, Figure 2 The surface of the end 22a of the first and second electrical conductors is shown above, the surface being used to receive an electrical connection. The electrical connection is implemented in a plane perpendicular to the rotation axis of the machine. The plane of the electrical connection is less than 40 mm away from the stator mass block, particularly approximately 27 mm.

[0184] After the electrical conductors exit the two recesses, the electrical connection is formed precisely on the electrical conductors at the axial end of the stator mass block. Each of the two conductors includes an inclined portion 22b, which approaches the other from one side.

[0185] The electrical conductors are distributed in the grooves and form a distributed winding; in this example, a fractional-slot winding is described. In this example, the number of grooves is 60. The number of stator poles is 8. Thus, the combination of the number of stator grooves / number of poles is 60 / 8.

[0186] The electrical conductors form a fractional-slot winding. For this fractional-slot winding, the ratio q, defined by q = Ne / (2pm), is written as an irreducible fraction z / n, where z and n are two non-zero integers, n being different from 1. Here, Ne is the number of stator slots, m is the number of winding phases, and p is the number of stator pole pairs. In particular, in the case of a three-phase fractional-slot winding, Figure 4 Above, one coil per phase was observed individually. Thus, for this machine with 60 slots and 8 poles, q = 60 / (3x8) = 5 / 2 was obtained. The coil is formed by the incoming conductor of the same phase passing through adjacent slots and the return conductor of the same phase passing through adjacent slots.

[0187] Electrical conductors 22 are arranged in rows along the aligned electrical conductors in the groove 21.

[0188] The electrical conductor may have a generally rectangular cross-section, particularly with rounded corners. In the example described, the electrical conductors are depicted as being radially stacked in a single row. The circumferential dimension of the electrical conductors substantially corresponds to the width of the groove. Thus, the groove includes only one electrical conductor within its width. The groove may include multiple electrical conductors within its radial dimension. In the described example, the groove includes two electrical conductors.

[0189] The electrical conductor 22 is made of copper or aluminum or any other conductive material that has been glazed or coated with any other suitable insulating coating.

[0190] Figure 6 The variation in the radial air gap field (in Tesla) caused solely by the inductive response, changing with angular position (in °), is visible above. Curve A illustrates this variation for a stator with a closed groove according to the invention. Curve A is compared to curve B, which illustrates the variation for a stator with a semi-open groove and a 2 mm opening. It can be seen that the radial air gap field (curve A) obtained by the stator according to the invention has fewer harmonics.

[0191] In the example just described, the groove includes two electrical conductors with different phases, each conductor being formed by only one strand.

[0192] exist Figures 7 to 9 In a variant of the implementation, each electrical conductor includes a plurality of pins, each of which forms a strand 32 in the groove. Thus, each electrical conductor includes three strands 32. All strands 32 of the same electrical conductor 22 are electrically connected to each other at each of the two axial ends 22a of all strands at the outlet of the groove.

[0193] in addition, Figure 5 and Figure 6The stator consists of 63 slots and 6 stator poles. Therefore, the ratio of the number of stator slots to the number of poles is 63 / 6.

[0194] Thus, the electrical conductors form a fractional-slot winding. For this fractional-slot winding, the ratio q, defined by q = Ne / (2pm), is written as an irreducible fraction z / n, where z and n are two non-zero integers, n being different from 1. Here, Ne is the number of stator slots, m is the number of winding phases, and p is the number of stator pole pairs. In particular, in the case of a three-phase fractional-slot winding, Figure 9 Above, one coil per phase was observed individually. Thus, for this machine with 63 slots and 6 poles, q = 63 / (3x6) = 7 / 2 is obtained. The coil is formed by the incoming conductor of the same phase passing through adjacent slots and the return conductor of the same phase passing through adjacent slots.

[0195] Each electrical conductor 22 is surrounded by an insulating sheet (not visible in the drawings) that insulates the electrical conductor from the walls 33 and 36 of the groove, and also insulates the electrical conductors 22 of different phases within the groove from each other.

[0196] In the described example, such as Figure 5 As can be seen above, the groove 21 has radial edges 33 that are parallel to each other and has a generally rectangular cross section in a plane perpendicular to the rotation axis of the machine.

[0197] Except for notch 40, such as Figure 5 As can be seen above, the shape of the bottom 35 of the groove 21 is substantially complementary to the shape of the electrical conductor 22.

[0198] The bottom 35 of the groove 21 is connected to the radial edge 33 by a fillet 38. The notch 40 of each groove 21 is centered on the bottom of the groove 35 and extends along the rotational axis of the machine. In embodiments not shown, the notch is not centered, or the bottom 35 includes multiple notches.

[0199] The notch 40 has a generally semi-circular rounded shape in cross-section in a plane perpendicular to the axis. The groove has a depth p between 0.3 mm and 0.6 mm (e.g., equal to 0.5 mm).

[0200] The presence of the notch 40 results in a localized narrowing of the material bridge 27. This narrowing allows for magnetic saturation of the metal plate, resulting in a lower magnetic flux along the bridge 27, which restricts the passage of magnetic flux.

[0201] Preferably, the minimum width l of the material bridge 27 is between 0.2 mm and 0.5 mm, for example, equal to 0.35 mm.

[0202] The groove has a generally rectangular cross-section. All or part of the groove may include a radial edge 33 with ribs 42, such as... Figure 10 As shown above. Each rib 42 extends parallel to the axis of rotation of the machine. The rib 42 is located in the middle portion of the radial edge 33, and essentially midway between the bottom of the groove 36 on the side where the magnetic yoke 29 is located and the material bridge 27 that closes the groove.

[0203] The stator mass block 25 is formed of a set of magnetic metal plates stacked along the axis of rotation, the metal plates being, for example, identical and precisely stacked. The metal plates can be held in place by snap-fitting, gluing, riveting, using tirants, welding, and / or any other technique. The magnetic metal plates are preferably made of magnets. The teeth 23 of the stator mass block 25 may have complementary undulations on their surfaces, which allows the different metal plates constituting the stator mass block 25 to snap together.

[0204] The stator can be obtained by means of a manufacturing method in which an electrical conductor 22 is inserted into a groove 21 from one or both of the axial ends of the stator by sliding it into the groove 21 along an axis parallel to the longitudinal axis of rotation.

[0205] In this invention, all electrical conductors having free ends located at the same circumferential position around the axis of rotation of the machine are electrically connected together, regardless of their radial position.

[0206] Of course, the present invention is not limited to the embodiments described above, and the rotor associated with the described stator may be a wound rotor, a squirrel-cage rotor, a permanent magnet rotor, or a variable reluctance rotor.

[0207] The term "includes" is understood to be synonymous with "includes at least one".

Claims

1. A stator (2) of a rotary electric machine (1), the stator comprising a stator mass block (25), the stator mass block comprising teeth (23) and grooves (21) between the teeth (23), each of the grooves being completely closed on the side where the air gap is located, an electrical conductor (22) being accommodated in the groove, the electrical conductor forming a single fractional slot winding, for the fractional slot winding, a ratio q defined by q=Ne / (2pm) is written in the form of an irreducible fraction z / n, where z and n are two non-zero integers, n being different from 1, wherein, Ne is the number of stator slots, m is the number of winding phases, and p is the number of stator pole pairs. At least a portion of the electrical conductor is in the form of a pin. The electrical conductors are electrically connected together in the stator.

2. The stator according to claim 1, wherein most of the electrical conductors are in the form of pins.

3. The stator according to claim 1 or 2, wherein the pin is U-shaped or I-shaped.

4. The stator according to claim 1 or 2, wherein the electrical conductors form a distributed winding.

5. The stator according to claim 1 or 2, wherein a majority of the electrical conductor is in the form of a U-shaped or I-shaped pin, the pin extending axially in the groove.

6. The stator according to claim 1 or 2, wherein the groove may be closed by a magnetic hoop on the side where the air gap is located.

7. The stator according to claim 6, wherein the magnetic hoop may have at least one locally narrowed portion, the at least one locally narrowed portion being formed by at least one notch (40).

8. The stator according to any one of claims 1, 2 and 7, wherein at least one groove is continuously closed on the side where the air gap is located by a material bridge (27), the material bridge being integrally formed with the tooth (23) defining the groove.

9. The stator according to claim 8, each of the material bridges (27) has at least one local narrowing, the at least one local narrowing being formed by at least one notch (40).

10. The stator according to any one of claims 1, 2, 7 and 9, wherein the groove is closed on the side opposite to the air gap by a magnetic yoke (29), the magnetic yoke being added to or integrally formed with the tooth.

11. The stator according to any one of claims 1, 2, 7 and 9, wherein the electrical conductor (22) has a generally rectangular cross-section.

12. The stator according to any one of claims 1, 2, 7 and 9, wherein each groove (21) comprises two to eight electrical conductors (22), each electrical conductor comprising one or more strands.

13. The stator according to any one of claims 1, 2, 7 and 9, wherein, The electrical conductor is in the form of a U-shaped pin, the U-shaped pin including a first leg and a second leg, the first leg and the second leg extending axially in a first groove A and a second groove R respectively, the first groove A and the second groove R being separated by a number of teeth Nd, the number of teeth Nd being strictly greater than 5.

14. The stator according to any one of claims 1, 2, 7 and 9, wherein, At least one groove (21) includes a radial edge with ribs.

15. The stator according to claim 14, wherein, All grooves include radial edges with ribs.

16. The stator according to any one of claims 1, 2, 7 and 9, wherein, At least one groove (21) has a straight or arc-shaped bottom.

17. The stator according to claim 16, wherein, All grooves have a straight or rounded bottom.

18. The stator according to any one of claims 1, 2, 7 and 9, wherein, The groove is configured to allow the passage of cooling fluid.

19. A stator (2) of a rotary electric machine (1), the stator comprising a stator mass block (25), the stator mass block comprising teeth (23) and grooves (21) between the teeth (23), each of the grooves being at least partially closed on the side where the air gap is located, an electrical conductor (22) being accommodated in the groove and distributed on at least two layers, the electrical conductor forming a single fractional slot winding, for which the ratio q defined by q=Ne / (2pm) is written in the form of an irreducible fraction z / n, z and n being two non-zero integers, n being different from 1, wherein, Ne is the number of stator slots, m is the number of winding phases, and p is the number of stator pole pairs. At least a portion of the electrical conductor is in the form of a pin. The electrical conductors are electrically connected together in the stator.

20. The stator according to claim 19, wherein most of the electrical conductors are in the form of pins.

21. The stator according to claim 19 or 20, wherein the pin is U-shaped or I-shaped.

22. The stator according to claim 19 or 20, wherein the electrical conductor is accommodated in the groove and distributed on only two layers.

23. A rotary electric motor (1) comprising a stator (2) and a rotor according to any one of the preceding claims.

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