EP3613127A1

EP3613127A1 - Rotating electrical machine with variable stator slot width

Info

Publication number: EP3613127A1
Application number: EP18717087.3A
Authority: EP
Inventors: Radu Fratila; Jérome Legranger
Original assignee: Valeo Equipements Electriques Moteur SAS
Current assignee: Valeo Equipements Electriques Moteur SAS
Priority date: 2017-04-20
Filing date: 2018-04-19
Publication date: 2020-02-26
Also published as: FR3065591B1; JP2020518218A; US20200052533A1; WO2018193012A1; CN110521084A; FR3065591A1

Abstract

The invention relates mainly to a rotating electrical machine (10) for a motor vehicle, comprising: - a rotor; - a stator (11) extending along an axis, said stator (11) comprising a body (24) provided with a plurality of stator teeth (28) defining slots (30, 30'), - the stator (11) comprising a winding with conductors (35) housed in the slots (30, 30'); - in a plane (P) orthogonal to the axis along which the stator (11) extends, - a first slot (30) has a first width (L1) measured in an orthoradial direction, radially in the middle of the first slot (30), and - a second slot (30'), separate from the first slot (30), has a second width (L2) measured along an orthoradial direction, radially in the middle of the second slot (30'); characterised in that the first slot width (L1) is different from the second slot width (L2).

Description

ROTATING ELECTRICAL MACHINE WITH INSERT WIDTH

STATORIC VARIABLE

The present invention relates to a rotating electrical machine with variable stator slot width. In known manner, the rotating electrical machines comprise a stator and a rotor secured to a shaft. The rotor may be integral with a driving shaft and / or driven and may belong to a rotating electrical machine in the form of an alternator, an electric motor, or a reversible machine that can operate in both modes. The stator is mounted in a housing configured to rotate the shaft on bearings by bearings. The rotor comprises a body formed by a stack of sheets of sheet metal held in pack form by means of a suitable fastening system. The rotor comprises poles formed by permanent magnets housed in cavities formed in the magnetic mass of the rotor.

Furthermore, the stator comprises a body consisting of a stack of thin sheets forming a ring, whose inner face is provided with notches open inwardly to receive phase windings. These windings pass through the notches and form buns protruding from both sides of the stator body. The phase windings are obtained for example from a continuous wire covered with enamel or from conductive elements in the form of pins connected together by welding. These windings are polyphase windings connected in star or delta whose outputs are connected to an inverter that can also operate as a bridge rectifier.

The invention aims to optimize the configuration of such an electric machine by reducing torque ripple and magnetic noise.

For this purpose, the subject of the invention is a rotary electric machine for a motor vehicle comprising:

- a rotor, a stator extending along an axis, said stator comprising a body provided with a plurality of stator teeth delimiting notches,

the stator comprising a winding comprising conductors housed in the notches,

in a plane orthogonal to the axis in which the stator extends,

a first notch has a first width measured in an orthoradial direction and radially in the middle of the first notch,

a second notch distinct from the first notch has a second width measured in an orthoradial direction and radially in the middle of the second notch,

characterized in that the first notch width is different from the second notch width.

The invention thus makes it possible, thanks to the implementation of notches of different widths, to effectively reduce the magnetic noise as well as the torque ripple of the rotating electrical machine.

In one embodiment, said rotating electrical machine has a configuration of 1 or 1, 5 or 2 notches per pole and per phase.

In one embodiment, the number of conductors per slot is an even number. In one embodiment, all the conductors have a section of the same area.

In one embodiment, all the conductors have a section of the same shape.

According to one embodiment, a ratio between the first notch width divided by the second notch width is between 1 .10 and 1 .35.

According to one embodiment, the ratio between the first notch width divided by the second notch width is between 1 .15 and 1 .25.

In one embodiment, the notches are parallel edges.

In one embodiment, the stator teeth have parallel edges. According to one embodiment, the stator has an alternation of first notches and second notches along its circumference.

In one embodiment, the stator has an alternation of a first set of first notches and a second set of second notches along its circumference.

In one embodiment, the first and second set of notches each have between two and nine notches, the two sets of notches having the same number of notches.

According to one embodiment, each stator tooth comprises a tooth root, the tooth roots all having the same circumferential length, said circumferential length being measured along an internal periphery of the stator body.

In one embodiment, the first notch includes a notch insulator having a thickness different from that of the notch insulator of the second notch.

In one embodiment, the conductors are constituted by continuous son or pins electrically connected to each other.

In one embodiment, the stator body is a one-piece or segmented laminated stator. According to one embodiment, the winding is of star or triangle type.

According to another aspect, the subject of the invention is a rotary electric machine for a motor vehicle comprising:

- a rotor,

a stator comprising a body provided with a plurality of stator teeth delimiting notches,

the stator comprising a coil comprising conductors housed in each slot,

in a plane orthogonal to the axis in which the stator extends,

a first notch has a first width measured in an orthoradial direction and radially in the middle of the first notch, a second notch distinct from the first notch has a second width measured in an orthoradial direction and radially in the middle of the second notch,

characterized in that the first notch comprises a notch insulator having a thickness different from that of the notch insulator of the second notch.

The invention will be better understood on reading the description which follows and on examining the figures which accompany it. These figures are given for illustrative but not limiting of the invention. Figure 1 is a longitudinal sectional view of a rotary electric machine according to the present invention;

Figure 2 is a perspective view of the wound stator and the rotor of the rotating electrical machine according to the present invention;

Figures 3a-3e are partial cross-sectional views of the stator according to the present invention illustrating different variable width slot patterns;

FIGS. 4a and 4b show graphical representations respectively of the evolution of the reduction of the torque ripple and of the revolution of the loss of the average torque as a function of the ratio between a first notch width and a second notch width. .

Identical, similar or similar elements retain the same reference from one figure to another.

FIG. 1 shows a rotating electrical machine 10 comprising a polyphase stator 1 1 surrounding a rotor 12 mounted on a shaft 13. The stator January 1 surrounds the rotor 12 with the presence of an air gap between the inner periphery of the stator January 1 and the periphery external rotor 12. The stator 1 1 is mounted in a housing 14 provided with a front bearing 15 and a rear bearing 16 rotatably supporting the shaft 13.

This electrical machine 10 may in particular be intended to be coupled, via a pinion 17, to a member of a traction chain of motor vehicle, such as a gearbox. The machine 10 is able to operate in an alternator mode to supply, in particular, energy to the battery and to the on-board vehicle network, and in a motor mode, not only to start the engine of the vehicle, but also to participate in pulling the vehicle alone or in combination with the engine. Alternatively, the electric machine 10 may be implanted on a motor vehicle axle, in particular a rear axle. Alternatively, the electric machine 10 takes the form of an electric motor or a non-reversible generator. The power of the electric machine 10 is advantageously between 8kW and 30kW.

More precisely, as can be seen in FIG. 2, the rotor 12 comprises a body 19 in the form of a bundle of sheets. Permanent magnets 20 may be implanted radially inside the pack of sheets, the lateral faces vis-à-vis two consecutive magnets 20 being of the same polarity. The rotor 12 is then of flux concentration type. Alternatively, the permanent magnets 20 may be implanted inside cavities 21 in a V configuration. Alternatively, the permanent magnets 20 extend ortho-radially inside the cavities 21 of the body 19. The magnets 20 may be in rare earth or ferrite depending on the applications and the desired power of the machine 10.

Furthermore, the stator January 1 extends along an axis X corresponding to the axis of the shaft 13. The stator January 1 comprises a body 24 constituted by a bundle of sheets and a coil 25. The body 24 is formed by a stack of sheet sheets independent of each other and maintained in pack form by means of a suitable fastening system. The stator body 24 may be of monoblock or segmented type, that is to say that it may be made from a plurality of sections each defining an angular portion of the body and mechanically connected to each other.

The body 24 is provided with statoric teeth 28 defining two by two notches 30, 30 'for mounting the stator winding 25. Thus, two successive notches are separated from each other by a tooth 28.

In the example shown, the notches 30, 30 'have parallel edges. However, the invention is also applicable with statoric teeth 28 with parallel edges, that is to say with notches 30, 30 'trapezoidal section.

In addition, each tooth 28 has a tooth root 31 visible in FIGS. 3a to 3e. The tooth roots 31 all have the same circumferential length which is measured along an inner periphery of the stator body 24.

The coil 25 comprises a set of phase windings 26 passing through the notches 30 and forming sprockets 33 projecting on either side of the stator body 24. The outputs of the phase windings 26 are connected to an inverter 34 can also operate as a rectifier bridge. For this purpose, the inverter 34 comprises power modules provided with power switching elements, such as MOS type transistors, connected to the phase outputs of the winding 25.

The coil 25 is formed from a plurality of conductors 35 constituted by pins 37. These pins 37 may have a U-shaped whose ends of the branches are connected together by welding. Alternatively, the coil 25 is formed from continuous conductive yarns wound inside the stator January 1 in the notches 30, 30 'to form one or more turns. The phase windings 26 are each associated with a series of notches 30, 30 '. Advantageously, the stator January 1 comprises a single or two independent three-phase systems each formed by three phase windings 26. Each three-phase system may be coupled in a triangle or star.

More precisely, two consecutive notches 30, 30 'of a series are separated by adjacent notches corresponding to the other phases. Thus, when there are K phases, the conductors 35 of the same phase winding 26 are inserted every K + 1th notches. For example, if the winding of the first phase is inserted in the notch 1, it is then inserted in the 4th notch for a simple three-phase machine, with one notch per pole and per phase, ie K = 3. It is also possible to provide a configuration with two notches per pole and per phase. It should be noted that the same notch 30, 30 'may receive drivers 35 belonging to two different phase windings in a preferred configuration of 1, 5 notches per pole and per phase.

The number of conductors 35 inside each notch 30, 30 'is advantageously even. In FIGS. 3a to 3e, each notch 30, 30 'contains 2 conductors. In a variant, the stator 11 may comprise 4 or 6 conductors per slot 30, 30 '.

Preferably, inside the notches 30, 30 ', all the conductors 35 have a section of the same area. In addition, all the conductors have a section of the same shape, such as a square shape, rectangle, flat, round. Conductors 35 are stacked radially relative to each other within a notch 30, 30 '.

Furthermore, as can be seen in FIG. 3a, following an orthogonal plane P to the axis in which the stator 11 extends, at least one first notch 30 has a first width L1 and at least a second notch 30. distinct from the first notch 30 has a second width L2.

The widths L1, L2 are measured in a direction orthoradial with respect to the axis X and radially in the middle of the corresponding notch 30, 30 '. The first slot width L1 is different from the second slot width L2. In this case, the slot width L1 is greater than the slot width L2.

In other words, the cross sectional area of the first notch 30 is different from the cross sectional area of the second notch 30 '. Accordingly, for conductors 35 all having cross sections of the same area, the fill rate of the first notch 30 is different from that of the second notch 30 '.

In addition, the first notch 30 includes a slot insulator 39 for electrically insulating the conductors 35 relative to the stator body 24 which has a different thickness, here higher than that of the notch insulation 39 of the second notch 30'. Only two slot insulators 39 have been shown in FIG. 3a to facilitate its readability, but it is clear that a slot insulator 39 is positioned inside each slot 30, 30 'between the conductor 35 and the inner faces of the corresponding notch 30, 30'.

In the example shown in FIG. 3a, the stator January 1 presents an alternation of first notches 30 and second notches 30 'according to its circumference, that is to say that one meets, according to the circumference of the stator 1 1, a first notch 30 of first width L1 then immediately after a second notch 30 'of second width L2, then immediately after a first notch 30 of first width L1, then immediately after a second notch 30' of second width L2 and so after.

Alternatively, as shown in FIGS. 3b to 3e, the stator January 1 has, along its circumference, an alternation of a first set E1 of first notches 30 adjacent to each other and a second set E2 of second notches 30 'adjacent to each other. Thus, following the circumference of the stator January 1, there is successively a first set E1 of notches 30, and immediately after this first set E1 of notches 30, a second set of E2 notches 30 ', and immediately after this second set E2 notches 30 ', a first set E1 notches 30, then a second set E2, and so on along the circumference of the stator January 1.

The first and second sets of notches E1, E2 each have between 2 and 9 notches 30, 30 '. The two sets of notches E1, E2 have the same number of notches 30, 30 '. In the embodiment of FIG. 3b, the first set E1 and the second set E2 of notches 30, 30 'comprise two notches each. In the embodiment of Figure 3c, the first set E1 and the second set E2 of notches 30, 30 'have three slots 30 each. In the embodiment of Figure 3d, the first set E1 and the second set E2 of notches 30, 30 'have six notches each. In the embodiment of Figure 3e, the first set E1 and the second set E2 notches 30, 30 'have nine notches each. FIG. 4a illustrates the evolution of the torque reduction R_ond as a function of a ratio between the first slot width L1 and the second slot width L2 for an alternation of a first notch 30 and a notch 30. a second single notch 30 '(see curve C1), as well as for an alternation of a first and a second set of notches E1, E2 each respectively having two notches (see curve C2), three notches (cf. curve C3), six notches (see curve C4), and nine notches (see curve C5).

FIG. 4b illustrates the evolution of the average torque loss P_C as a function of a ratio between the first slot width L1 and the second slot width L2 for an alternation of a first notch 30 and a second notch 30 'single (see curve C1'), and for an alternation of a first and a second set of notches E1, E2 each respectively comprising two notches (see curve C2 '), three notches (cf curve C3 '), six notches (see curve C4'), and nine notches (see curve C5 ').

The curves of FIGS. 4a and 4b were obtained for a synchronous machine with permanent magnets comprising three phases and four pairs of poles. The electric machine 10 further has a configuration of 1.5 notches per pole and per phase. However, the invention is not limited to a machine with four pairs of poles, but it can be implemented with a machine having any polarity. The number of phases can also be adapted according to the application.

Advantageously, a range of values PI 1 is selected on which the ratio between the first slot width L1 divided by the second slot width L2 is between 1 .10 and 1 .35. According to an optimum configuration, this ratio L1 / L2 is in the range Pl_2 ranging between 1 .15 and 1 .25.

For all the notch patterns 30, 30 ', such a range leads to a good compromise between the decrease in the torque ripple and the decrease in the average torque. Indeed, such a range of values makes it possible to obtain a significant reduction in the ripple of the torque that can reach nearly 20%, while generating a maximum average torque loss of less than 5%. For a ratio L1 / L2 exceeding 1 .30, it is observed that the reduction of the torque ripple begins to fade.

Furthermore, the electrical machine 10 may comprise a cooling liquid circuit including an inlet and a liquid cooling outlet for circulating the liquid in a chamber 44 arranged at the outer periphery of the stator January 1, as shown in FIG. 2. The electric machine 10 can thus be cooled by water or oil.

Of course, the foregoing description has been given by way of example only and does not limit the scope of the invention which would not be overcome by replacing the different elements by any other equivalent.

In addition, the various features, variations, and / or embodiments of the present invention may be associated with each other in various combinations, to the extent that they are not incompatible or exclusive of each other.

Claims

1. Rotary electrical machine (10) for a motor vehicle comprising:

a rotor (12),

a stator (1 1) extending along an axis (X), said stator (1 1) comprising a body provided with a plurality of stator teeth (28) delimiting notches (30, 30 '),

the stator (1 1) comprising a winding (25) comprising conductors (35) housed in the notches (30, 30 '),

in an orthogonal plane (P) to the axis in which the stator (1 1) extends,

a first notch (30) has a first width (L1) measured in an orthoradial direction and radially in the middle of the first notch (30),

a second notch (30 ') distinct from the first notch (30) has a second width (L2) measured in an orthoradial direction and radially in the middle of the second notch (30'),

characterized in that the first notch width (L1) is different from the second notch width (L2).

2. A rotary electric machine according to claim 1, characterized in that it has a configuration of 1 or 1, 5 or 2 notches per pole and per phase.

3. Rotating electrical machine according to claim 1 or 2, characterized in that the number of conductors (35) per notch (30, 30 ') is an even number.

4. rotary electric machine according to any one of claims 1 to 3, characterized in that all the conductors (35) have a section of the same area.

5. Rotating electrical machine according to any one of claims 1 to 4, characterized in that all the conductors (35) have a section of the same shape.

6. Rotating electric machine according to any one of claims 1 to 5, characterized in that a ratio between the first notch width (L1) divided by the second notch width (L2) is between 1 .10 and 1 .35.

7. Rotating electric machine according to claim 6, characterized in that the ratio between the first notch width (L1) divided by the second notch width (L2) is between 1 .15 and 1 .25.

8. rotary electric machine according to any one of claims 1 to 7, characterized in that the notches (30, 30 ') have parallel edges.

9. rotating electrical machine according to any one of claims 1 to 8, characterized in that the stator teeth (28) have parallel edges.

10. A rotary electric machine according to any one of claims 1 to 9, characterized in that the stator (1 1) has an alternation of first notches (30) and second notches (30 ') along its circumference.

1 1. Rotary electric machine according to any one of claims 1 to 9, characterized in that the stator (1 1) has an alternation of a first set (E1) of first notches (30) and a second set (E2) second notches (30 ') along its circumference.

12. Rotating electric machine according to claim 1 1, characterized in that the first and second set of notches (E1, E2) each comprise between two and nine notches (30, 30 '), the two sets of notches ( E1, E2) having the same number of notches (30, 30 ').

13. A rotary electric machine according to any one of claims 1 to 12, characterized in that each stator tooth (28) comprises a tooth root (28), the tooth feet (28) all having the same circumferential length, said circumferential length being measured along an inner periphery of the stator body (24).

14. A rotary electric machine according to any one of claims 1 to 13, characterized in that the first notch (30) comprises a notch insulator (39) having a thickness different from that of the notch insulation (39). ) of the second notch (30 ').

15. A rotary electric machine according to any one of claims 1 to 14, characterized in that the conductors (35) are constituted by continuous son or pins electrically connected to each other.