WO2023144384A1

WO2023144384A1 - Integrated insulation element and wedge elements for an electric excited rotor

Info

Publication number: WO2023144384A1
Application number: PCT/EP2023/052181
Authority: WO
Inventors: Karthikeyan SRIDHAR; Sabarirajan Rajendran; Sivasankar Muni
Original assignee: Valeo Eautomotive Germany Gmbh
Priority date: 2022-01-31
Filing date: 2023-01-30
Publication date: 2023-08-03

Abstract

The invention concerns a rotor (1) comprising a rotor shaft (4), a rotor body (2) formed of a stack of laminations having a plurality of teeth (21) projecting radially, a field coil (3) wound around each tooth of the plurality of teeth (21) and forming coil ends (31) projecting axially from respectively both axial ends of the rotor body (2), a plurality of wedge elements (110) extending axially and arranged in slots corresponding to space between two adjacent teeth of the plurality of teeth (21), two end caps (5), and two insulation elements (120) respectively arranged and configured to electrically insulate the coil ends (31) from the respective end cap (5), at least one of the two insulation elements (120) being integrally formed with at least an axial portion of the wedge elements of the plurality of wedge elements (110) into a one-piece assembly.

Description

TITLE OF INVENTION: Integrated insulation element and wedge elements for an electric excited rotor

FIELD OF THE INVENTION

The present invention belongs to the field of rotary electric machines configured to be on board of an automotive vehicle, such as an electric vehicle (EV) or a hybrid vehicle (HV).

The present invention relates in particular to the field of electric excited rotors, also called wound rotors or slip ring rotors, integrated to rotary electric machines.

BACKGROUND OF THE INVENTION

As is known, an electric or a hybrid automotive vehicle presents an electric drive comprising a rotary electric machine which needs to be supplied with electric power, for instance by a high voltage power supply battery, to deliver a mechanical power in order to ensure the propulsion of the vehicle.

In a general manner, the rotary electric machine comprises a stator, referring to a fixed part of the rotary electric machine, and a rotor, referring to a rotating part of the rotary electric machine. The rotor then comprises a rotor shaft configured to ensure the transmission of the mechanical power between the rotary electric machine and an exterior driven apparatus, notably the wheels of the vehicle.

In particular, it is known to have the rotor electric excited. This type of rotors is commonly referred as wound rotors or slip ring rotors. Such a rotor comprises a rotor body formed of a stack of laminations having a plurality of teeth projecting radially, and a field coil wound around the plurality of teeth. Then, the field coil is connected to an external power supply through slip rings. The slip rings correspond to electro-mechanical devices configured to allow the exchange of electric power between the field coil, which rotates with the rotor, and the external power supply, which is fixed.

However, in the context of the rotary electric machine for the electric or hybrid vehicles, the rotor is designed to rotate at high speeds, which may affect the holding of the field coil due to centrifugal forces. This may weaken the electrical insulation of the field coil, and even lead, in most extreme cases, to short-circuits or to a break of a tooth. For instance, a conventional solution to fix the field coil is to mount end caps on both axial ends of the rotor body and impregnate the field coil with resin. In this context, the main objective of the present invention is to provide a rotor with wedge elements which participates in fixating the field coil, such that the rotor is easier to produce and has a reduced manufacturing time.

SUMMARY OF THE INVENTION

More specifically, the present invention relates to a rotor for a rotary electric machine, the rotor comprising a rotor shaft configured to rotate around an axis of rotation, a rotor body formed of a stack of laminations having a plurality of teeth projecting radially, a field coil wound around each tooth of the plurality of teeth and forming coil ends projecting axially, respectively from both axial ends of the rotor body, a plurality of wedge elements, and two end caps. The rotor body is also commonly referred to as rotor package. The rotor body is mounted coaxially on the rotor shaft. The plurality of wedge elements extends axially and is arranged in slots corresponding to space between two adjacent teeth of the plurality of teeth. Then, each wedge element of the plurality of wedge elements is configured to come against respectively the corresponding two adjacent teeth. The two end caps are respectively located at both axial ends of the rotor body such that to cover the corresponding coil end of the field coil.

Then, the rotor further comprises two insulation elements respectively arranged and configured to electrically insulate the coil ends at both axial ends of the rotor body from the respective end cap. At least one of the two insulation elements is integrally formed with at least an axial portion of the wedge elements of the plurality of wedge elements into a one-piece assembly.

The present invention provides thus the substantial gain of reducing the number of components of the rotor, allowing thus to ease the manufacturing of the rotor. Compared to a solution in which all the wedge elements would have to be inserted one by one, the present invention allows to reduce the number of components to be mounted, and thus to reduce the related mounting time. Moreover, the one-piece assembly allows to add structural rigidity to the rotor, for an improved mechanical holding of the rotor through its in-service life.

Advantageously, the rotor comprises a potting material which fills the slots and the free space within the two end caps.

Advantageously, the wedge elements and the two end caps are configured to be sealed with the rotor body with respect to the potting material such that to ease the injection process of the potting material, notably by limiting potential leaks of the potting material.

In a preferred manner, each one of the two insulation elements is integrally formed respectively with a first axial portion of the wedge elements of the plurality of wedge elements and with a second axial portion of the wedge elements of the plurality of wedge elements such that to form two one-piece assemblies. Then, the first axial portion and the second axial portion of the wedge elements are configured to come in contact against one another at a joining interface and forming together the wedge elements of the plurality of wedge elements. Hence, the present invention allows to have only two parts (the two one-piece assemblies) to be mounted, compared to a solution with two insulation elements and all the wedge elements being mounted individually. The manufacturing of the rotor is consequently simplified and the related time of production is reduced.

Advantageously, the first axial portion and the second axial portion of the wedge elements of the plurality of wedge elements have an equal axial length.

Advantageously, the two one-piece assemblies are identical, if appropriate. Doing so allows to further ease the manufacturing of the rotor, as there is only one type of one-piece assembly to be produced.

According to an exemplary embodiment, the first axial portion and the second axial portion of the wedge elements of the plurality of wedge elements have a flat surface arranged at the joining interface and are glued together on said flat surface. Doing so, allows to have a sealed interface between the first axial portion and the second axial portion of the wedge elements with respect to the potting material. In this exemplary embodiment, the two one-piece assemblies may advantageously be identical.

According to another exemplary embodiment, the first axial portion and the second axial portion of the wedge elements of the plurality of wedge elements have a mechanical locking system arranged at the joining interface such that to attach together the first axial portion and the second axial portion. The mechanical locking system may advantageously provide a sealing effect with respect to the potting material.

Advantageously, for each wedge element of the plurality of wedge elements, the mechanical locking system may comprise a protruding portion and a recessed portion on both the first axial portion and of the second axial portion of the corresponding wedge element. Then, the protruding portion of the first axial portion of the respective wedge element especially complements the recessed portion of the second axial portion of the respective wedge element. Similarly, the recessed portion of the first axial portion of the respective wedge element especially complements the protruding portion of the second axial portion of the respective wedge element.

Advantageously, the two one-piece assemblies are axially pressed against one another at the joining interface by the two end caps. Preferably, the two one-piece assemblies may be mechanically sealed together with respect to the potting material, at the joining interface, by a pressing force applied by the two end caps on the two insulation elements of the two one-piece assemblies.

Advantageously, the plurality of wedge elements is made out of an insulation material, for instance a plastic material. Thus, the wedge elements may electrically insulate the field coil from the rotor body.

Advantageously, the plurality of wedge elements and the two insulation elements are made out of a same material, although it is also possible, if appropriate, to use two different materials for the insulation elements and for the wedge elements. Using the same material facilitates the manufacturing of the one-piece assembly.

According to an aspect of the invention, the invention relates to the rotary electric machine comprising the rotor as described previously and a stator.

Another aspect of the invention is the electric drive, comprising the rotary electric machine and an inverter configured to convert a direct current voltage coming from a high-voltage power supply battery into an alternating current voltage so as supply the stator of the rotary electric machine with the AC voltage. The AC voltage may be a multiphase AC voltage, especially a three- phase voltage. The rotor is advantageously supplied with a DC voltage. Preferably, a unique power converter is used for supplying both the AC voltage to the stator and the DC voltage to the rotor.

A further aspect of the invention is an electric of a hybrid vehicle, comprising the electric drive for driving the vehicle. The vehicle may comprise the high-voltage power supply battery, preferably a rechargeable battery for providing the DC voltage to the inverter, if applicable.

These and other objects, features, aspects and advantages of the present invention will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses preferred embodiments of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be better understood on reading the description that follows, and by referring to the appended drawings given as non-limiting examples, in which identical references are given to similar objects and in which:

Figure 1 is a schematic diagram of a view of an example of a rotor according to an embodiment of the invention; Figure 2 is a schematic diagram of a partial cut view of an example of the rotor according to an embodiment of the invention;

Figure 3 is a schematic diagram of a view of an example of an assembly of wedge elements and insulation elements according to an embodiment of the invention;

Figures 4 and 5 are schematic diagrams of views respectively of a first and a second example of a one-piece assembly comprising one insulation element and at least an axial portion of the wedge elements according to the invention;

Figure 6 is a schematic diagram of an automotive electric or hybrid vehicle comprising the rotor of a rotary electric machine according to an embodiment of the invention.

DETAILED DESCRIPTION

Selected embodiments of the present invention will now be explained with reference to the drawings. It will be apparent to those skilled in the art from this disclosure that the following descriptions of the embodiments of the present invention are provided for illustration only and not for the purpose of limiting the invention as defined by the appended claims and their equivalents.

In reference to Figure 6, an aspect of the invention is an electric vehicle or a hybrid electric automotive vehicle EV comprising wheels and an electric drive configured to drive at least indirectly at least one of the wheels of the vehicle. The vehicle may comprise a high-voltage power supply battery B, preferably a rechargeable battery, for providing electric power to the electric drive. Although, the invention is not limited to this domain.

Another aspect of the invention is the electric drive comprising a rotary electric machine M and an inverter I configured to convert a direct current (DC) voltage coming from the high-voltage power supply battery B into an alternating current (AC) voltage in order to supply a stator of the rotary electric machine M with AC voltage. The rotary electric machine M may in particular be a three-phase rotary electric machine supplied with a three-phase AC voltage. A rotor of the rotary electric machine is advantageously supplied with a DC voltage. Preferably, a unique power converter is used for supplying both the AC voltage to the stator and the DC voltage to the rotor.

The invention also relates to the rotary electric machine comprising the stator, referring to a fixed part of the rotary electric machine, and the rotor, referring to a rotating part of the rotary electric machine. The rotor is, in particular, an electric excited rotor, also commonly referred as a wound rotor or a slip ring rotor. More precisely, the stator presents an annular shape and surrounds coaxially the rotor. Then, the rotary electric machine comprises a casing covering both the stator and the rotor. Ordinarily, the stator comprises a stator body formed of a stack of stator laminations having a plurality of stator teeth projecting radially, and stator windings wound around the stator teeth.

Figure 1 discloses a partial view of an example of the rotor 1 according to a further aspect of the invention. The rotor 1 comprises a rotor shaft 4 configured to rotate around an axis X of rotation, a rotor body 2 formed of a stack of laminations having a plurality of teeth 21 projecting radially, and at least one field coil 3 wound around each tooth of the plurality of teeth 21 . The rotor body is also commonly referred to as rotor package. The plurality of teeth 21 may notably comprise four, six, or eight teeth for example. The laminations are especially stacked along the axis of rotation. The rotor body 2 is configured to be mounted coaxially on the rotor shaft 4, for instance the rotor body 2 may be press-fitted on the rotor shaft 4.

The field coil 3 is in particular connected to an external power supply through at least one slip ring (not represented in the drawings) mounted on the rotor shaft 4, namely on an axial end of the rotor shaft 4. The slip rings correspond to electro-mechanical devices configured to allow the exchange of electric power between a rotating element and a fixed element, here respectively the field coil and the external power supply.

Figure 2 illustrates a partial cut view of an example of the rotor. The field coil 3 notably passes through slots 22 corresponding to space between two adjacent teeth of the plurality of teeth 21 , and forms coil ends projecting axially from respectively both axial ends of the rotor body

2. The rotor may also present an insulation system 6 arranged on walls of the slots 22 between the rotor body 2 and the field coil 3 such that to electrically insulate the rotor body 2 from the field coil 3, for instance the insulation system 6 may be an insulation paper.

The rotor 1 may further comprise two end plates, configured to come respectively against both axial ends of the rotor body 2. The two end plates may present an annular shape, substantially similar to the shape of the two axial ends of the rotor body 2 such that to cover the two axial ends. Then, the field coil 3 may advantageously pass over the two end plates. In other words, the two end plates shall be located between the rotor body 2 and the coil ends 31 of the field coil 3 such that to provide a mechanical holding of the stack of laminations and to electrically insulate axially the field coil 3 from the rotor body 2.

Furthermore, as illustrated in Figure 1 , the rotor 1 comprises two end caps 5 respectively located at both axial ends of the rotor body 2 such that to cover the coil ends 31 of the field coil

3. Only one end cap is represented in the Figure 1 in order to provide an open view on the coil ends of the field coil on one side of the rotor 1 . The end caps are especially made of a metallic material, preferably an aluminum material. The rotor 1 also comprises a plurality of wedge elements 110 extending axially and arranged in the slots 22. In other words, each wedge element is placed between the corresponding two adjacent teeth of the plurality of teeth. Each wedge element of the plurality of wedge elements 110 is configured to come against respectively the corresponding two adjacent teeth. Moreover, each wedge element of the plurality of wedge elements 110 may have a substantially triangular cross section with a corner portion 118 being directed towards the axis X of rotation (as illustrated in Figure 2). Additionally, the plurality of wedge elements is advantageously made out of an insulation material, for instance a plastic material. Thus, the wedge elements may electrically insulate the field coil from the rotor body. The wedge elements also induce a limited mass increase of the rotor compared for instance to a solution in which heads of the teeth are close to one another.

Then, the slots 22 and the free space within the two end caps 5, closed radially by the wedge elements and axially by the two end caps 5, are notably filled with a potting material, for instance a resin, such that to fix the field coil. Advantageously, the wedge elements and the two end caps are configured to be sealed with the rotor body with respect to the potting material such that to ease the injection process of the potting material, notably by limiting potential leaks of the potting material. In addition, the wedge elements contribute to enhance the mechanical support of the field coil for an improved resistance to centrifugal forces. The two end caps provide in a similar manner the advantage of enhancing the mechanical holding of the rotor body. The field coil 3 is thus prevented from moving due to centrifugal forces during in-service life of the rotor, especially when the rotor rotates at a high speed.

In particular, as illustrated in Figure 1 , the two end caps 5 may have bores to enable the injection of the potting material through the bores of one of the two end caps 5, and to let air out on the bores of another one of the two end caps 5. An air vacuum system may be arranged on the other one of the two end caps 5 to assist the injection process of the potting material.

The rotor 1 also comprises two insulation elements 120 respectively arranged and configured to electrically insulate the coil ends 31 at both axial ends of the rotor body 2 from the respective end cap 5. Then, at least one of the two insulation elements 120 is integrally formed with at least an axial portion of the wedge elements of the plurality of wedge elements 110 into a one-piece assembly. In other words, the rotor comprises at least one one-piece assembly which is formed of one of the two insulation elements 120 and of the axial portions of all the wedge elements of the plurality of wedge elements. Preferably, the at least an axial portion of the wedge elements has a same length for all the wedge elements.

In a nutshell, the present invention provides the substantial gain of reducing the number of components of the rotor, allowing thus to ease the manufacturing of the rotor. Compared to a solution in which all the wedge elements would have to be inserted one by one, the present invention allows to reduce the number of components to be mounted, and thus to reduce the related mounting time. Moreover, the one-piece assembly allows to add structural rigidity to the rotor, for an improved mechanical holding of the rotor through its in-service life.

Moreover, the two insulation elements 120 may for instance be made of a plastic material. The plurality of wedge elements 110 and the two insulation elements 120 may advantageously be made out of a same material, although it is also possible if appropriate to use two different materials for the insulation elements and for the wedge elements. Using the same material facilitates the manufacturing of the one-piece assembly.

It can be noted that it is not necessary to have the insulation elements directly in contact with the field coil for providing electrical insulation between the coil ends of the field coil and the respective end cap. In particular, each one of the two insulation elements may be, on one side, in contact with the rotor body, and on another side, in contact with the corresponding end cap. Moreover, an axial length of the insulation element could be set higher than an axial length of the coil ends of the field coil. Then, the insulation element may act as a buffer between the corresponding end cap and the rotor body, while ensuring that the corresponding end cap does not come against the corresponding coil end.

For the one-piece assembly, the junction between the respective insulation element 120 and the at least an axial portion 111 of the wedge elements may preferably be smooth such that to ease the manufacturing process of the one-piece assembly and to reduce potential mechanical stress concentrations at this junction.

As illustrated in Figure 3, in a preferred manner, each one of the two insulation elements 120 is integrally formed respectively with a first axial portion 112 of the wedge elements of the plurality of wedge elements 110 and with a second axial portion 113 of the wedge elements of the plurality of wedge elements 110 such that to form two one-piece assemblies 130. In other words, one of the two one-piece assemblies 130 has one of the two insulation elements 120 and the first axial portion 112 of the wedge elements, and the other one of the two one-piece assemblies 130 has the other one of the two insulation elements 120 and the second axial portion 113 of the wedge elements. Hence, the present invention allows to have only two parts (the two one-piece assemblies) to be mounted, compared to a solution with two insulation elements and all the wedge elements being mounted individually. The manufacturing of the rotor is consequently simplified and the related time of production is reduced.

Then, the first axial portion 112 and the second axial portion 113 of the wedge elements are configured to come in contact against one another at a joining interface J and forming together the wedge elements of the plurality of wedge elements 110. The joining interface J is notably circled with a dashed circle in the Figure 3. The contact between the first axial portion 112 and the second axial portion 113 of the wedge elements may advantageously provide a sealing effect with respect to the potting material, if appropriate.

Alternatively, the rotor may comprise one of the two insulation elements as a single part, and only one one-piece assembly formed of the other one of the two insulation elements and the wedge elements of the plurality of wedge elements (embodiment not represented in the Figures). In such a configuration, the insulation element and the one-piece assembly would be fixated together at an axial end of the rotor body.

Regarding the manufacturing point of view, the two one-piece assemblies are especially configured to be mounted on the rotor body, after the winding of the field coil around the plurality of teeth, and before the injection of the potting material through the slots.

More specifically, the two one-piece assemblies may be inserted axially such that the wedge elements slide between adjacent teeth of the plurality of teeth. Hence, compared to a solution in which all the wedge elements are mounted individually, the present invention presents the advantage of reducing the number of components to be mounted, and the related manufacturing time.

Moreover, the two one-piece assemblies are preferably further axially pressed against one another at the joining interface by the two end caps, during the mounting of the end caps at both axial ends of the rotor body. More specifically, the end caps may apply a pressing force against the two insulation elements of the two one-piece assemblies. Preferably, the two one-piece assemblies may be mechanically sealed together with respect to the potting material, at the joining interface, by the pressing force applied by the end caps on the two insulation elements.

Moreover, the first axial portion 112 of the wedge elements may have the same length for all the wedge elements. In a similar manner, the second axial portion 113 of the wedge elements may have the same length for all the wedge elements. Thus, for each one of the two one-piece assemblies, the axial portions of the wedge elements especially have the same length. Then, the first axial portion 112 and the second axial portion 113 of the wedge elements of the plurality of wedge elements 110 may have an equal axial length. In such a case, both the first axial portion and the second axial portion of the wedge elements have the equal axial length. Although, it is possible to have a different axial length for, on one hand, the first axial portion of the wedge elements, and on the other hand, for the second axial portion of the wedge elements. Especially, the two one-piece assemblies 130 may be identical, if appropriate. Doing so allows to further ease the manufacturing of the rotor, as there is only one type of one-piece assembly to be produced. The plurality of wedge elements 110 may have an axial length slightly inferior to an axial length of the rotor body 2. This difference in length allows to have the wedge elements not over constrained, especially if they are made out of a plastic material.

Figures 4 and 5 illustrate respectively views of a first and a second exemplary embodiments of the one-piece assembly 130 according to the invention. It can be noted that only one one-piece assembly is represented in Figures 4 and 5 for the sake of clarity.

According to the first exemplary embodiment of the one-piece assembly 130 represented in Figure 4, the first axial portion and the second axial portion of the wedge elements of the plurality of wedge elements 110 have a flat surface 114 arranged at the joining interface and are glued together on said flat surface 114. For instance, some glue may be affixed on both or on either one ends respectively of the first axial portion and the second axial portion of the wedge elements at the joining interface, prior to the mounting of the two one-piece assemblies 130 on the rotor. Then, the first axial portion and the second axial portion of the wedge elements may be pressed together by the end caps. Doing so, allows to have a sealed interface between the first axial portion and the second axial portion of the wedge elements with respect to the potting material.

Moreover, in a configuration with two of the one-piece assemblies according to this first exemplary embodiment, the two one-piece assemblies may advantageously be identical, so that to simplify the manufacturing of the rotor.

According to the second exemplary embodiment of the one-piece assembly 130, as illustrated in Figure 5, the first axial portion and the second axial portion of the wedge elements of the plurality of wedge elements have a mechanical locking system 115 (circled by a dashed line in Figure 5) arranged at the joining interface such that to attach together the first axial portion and the second axial portion of the wedge elements of the plurality of wedge elements. The mechanical locking system 115 may advantageously provide a sealing effect with respect to the potting material. Using the mechanical locking system 115 allows to have an improved structural holding at the joining interface.

As an example, for each wedge element of the plurality of wedge elements, the mechanical locking system 115 may comprise a protruding portion 116 and a recessed portion 117 on both the first axial portion 112 and of the second axial portion 113 of the corresponding wedge element. Then, the protruding portion 116 of the first axial portion 112 of the respective wedge element especially complements the recessed portion 117 of the second axial portion 113 of the respective wedge element. Similarly, the recessed portion 117 of the first axial portion 112 of the respective wedge element especially complements the protruding portion 116 of the second axial portion 113 of the respective wedge element.

The mechanical locking system may also have a clipping system such that the first axial portion 112 and the second axial portion 113 of the wedge elements are clipped together.

Moreover, the mechanical locking system allows to avoid using glue for the mounting of the two one-piece assemblies. Although, the first axial portion 112 and the second axial portion 113 of the wedge elements may be further glued together, if appropriate.

In particular, the respective insulation element and the at least an axial portion of the wedge elements may be overmolded such that to form the one-piece assembly.

The at least one-piece assembly 130 may also be produced through an injection molding process using a mold. For example, the mold may have two half-molds. Then, one of the two halfmolds may provide the shape of the insulation element, and the other one of the two half-molds may provide the shape of the axial portions of the wedge elements. In other words, the junction between the two half-molds may coincide with the junction between the insulation element and the axial portions of the wedge elements.

Although embodiments have been described with reference to a number of illustrative embodiments thereof, it should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the spirit and scope of the principles of this disclosure.

Claims

CLAIMS A rotor (1 ) for a rotary electric machine (M), the rotor (1) comprising:

- a rotor shaft (4) configured to rotate around an axis (X) of rotation;

- a rotor body (2) formed of a stack of laminations having a plurality of teeth (21 ) projecting radially, the rotor body (2) being mounted coaxially on the rotor shaft (4);

- a field coil (3) wound around each tooth of the plurality of teeth (21 ) and forming coil ends (31 ) projecting axially, respectively from both axial ends of the rotor body (2);

- a plurality of wedge elements (110) extending axially and arranged in slots (22) corresponding to space between two adjacent teeth of the plurality of teeth (21 ), each wedge element of the plurality of wedge elements (110) being configured to come against respectively the corresponding two adjacent teeth;

- two end caps (5) respectively located at both axial ends of the rotor body (2) such that to cover the corresponding coil end (31 ) of the field coil (3), characterized in that the rotor (1 ) comprises two insulation elements (120) respectively arranged and configured to electrically insulate the coil ends (31 ) at both axial ends of the rotor body (2) from the respective end cap (5), at least one of the two insulation elements (120) being integrally formed with at least an axial portion (111 ) of the wedge elements of the plurality of wedge elements (110) into a one-piece assembly (130). The rotor (1 ) as claimed in the claim 1 , wherein each one of the two insulation elements (120) is integrally formed respectively with a first axial portion (111 , 112) of the wedge elements of the plurality of wedge elements (110) and with a second axial portion (111 , 113) of the wedge elements of the plurality of wedge elements (110) such that to form two one-piece assemblies (130), the first axial portion (111 , 112) and the second axial portion (111 , 113) of the wedge elements being configured to come in contact against one another at a joining interface (J) and forming together the wedge elements of the plurality of wedge elements (110). The rotor (1 ) as claimed in the previous claim, wherein the first axial portion (111 , 112) and the second axial portion (111 , 113) of the wedge elements of the plurality of wedge elements (110) have an equal axial length. The rotor (1 ) as claimed in any of the claims 2 or 3, wherein the two one-piece assemblies (130) are identical. The rotor (1 ) as claimed in any of the claims 2 to 4, wherein the first axial portion (111 , 112) and the second axial portion (111 , 113) of the wedge elements of the plurality of wedge elements (110) have a flat surface (114) arranged at the joining interface (J) and are glued together on said flat surface (114). The rotor (1 ) as claimed in any of the claims 2 to 4, wherein the first axial portion (111 , 112) and the second axial portion (111 , 113) of the wedge elements of the plurality of wedge elements (110) have a mechanical locking system (115) arranged at the joining interface (J) such that to attach together the first axial portion (111 , 112) and the second axial portion (111 , 113). The rotor (1 ) as claimed in any of the preceding claims, wherein the plurality of wedge elements (110) is made out of an insulation material. The rotor (1 ) as claimed in any of the preceding claims, wherein the plurality of wedge elements (110) and the two insulation elements (120) are made out of a same material. The rotor (1 ) as claimed in any of the preceding claims combined with claim 2, wherein the two one-piece assemblies (130) are axially pressed against one another at the joining interface (J) by the two end caps (5). The rotor (1) as claimed in any of the preceding claims, comprising a potting material which fills the slots (22) and the free space within the two end caps (5). A rotary electric machine (M) for an electric or a hybrid vehicle (EV), the rotary electric machine (M) comprising the rotor (1 ) according to any of the preceding claims.