Permanent-magnet rotor and electric machine

Abstract

The invention relates to a permanent-magnet rotor (1) for an electric machine (2), comprising a rotor body (3) having a plurality of magnet pockets (4) for receiving permanent magnets (5) which are configured to form alternating magnetically opposed rotor poles (6) distributed over the circumference of the rotor body (3), wherein circumferentially adjacent magnet pockets (4) of a rotor pole (6) are each separated from one another by a radially extending bridge (7), wherein an opening (8) in the form of a circular ring segment is formed in the rotor body (3) so as to be radially aligned with and radially outwardly spaced from at least one bridge (7).

Description

[0001] Permanent magnet rotor and electric machine

[0002] The present invention relates to a permanent magnet-excited rotor for an electrical machine, comprising a rotor body with a plurality of magnetic pockets for accommodating permanent magnets, which are configured to form alternating, magnetically opposite rotor poles distributed over the circumference of the rotor body. Adjacent magnetic pockets of a rotor pole in the circumferential direction are each separated from one another by a web extending in the radial direction. The invention further relates to an electrical machine.

[0003] The state of the art in the field of permanent magnet rotors for electrical machines is characterized by a multitude of developments aimed at optimizing the performance, efficiency, and operational reliability of these components. Permanent magnet rotors utilize permanent magnets positioned in specifically designed pockets of the rotor body to generate a permanent magnetic field that, in interaction with the electric field generated by the stator, produces the torque of the electrical machine.

[0004] A key problem with permanent magnet rotors is the mechanical stress, which occurs particularly at high speeds. The centrifugal force acting on the rotor components, especially the permanent magnets and the surrounding structures such as magnet pockets and webs, can lead to plastic deformation or even component failure. This stress can significantly impair the reliability and service life of the machine and therefore represents a significant technical challenge.

[0005] Another significant problem associated with permanent magnet rotors is the limitation of electromagnetic efficiency due to parasitic effects. These include unwanted stray fluxes, which can reduce the efficiency of torque generation. The specific configuration and arrangement of the permanent magnets and webs in the rotor significantly influence these stray fluxes. In particular, a non-optimized arrangement and dimensioning of these elements leads to a deterioration in performance, which limits the efficiency and power density of the electric machine.

[0006] The simultaneous fulfillment of mechanical and electromagnetic requirements reflects a significant bottleneck in the state of the art. While conventional solutions such as modifying the web or magnet pocket configuration can improve certain aspects such as mechanical stability, they often result in a deterioration of electromagnetic performance. In particular, reducing mass in critical areas of the rotor to reduce centrifugal loading has proven detrimental to effective torque generation, as this can have undesirable effects on the magnetic field and thus on the efficiency of the machine.

[0007] It is therefore the object of the invention to eliminate or at least reduce the problems known from the prior art and to provide a correspondingly improved permanent magnet rotor for an electrical machine.

[0008] It is also the object of the invention to realize an optimized electrical machine.

[0009] This object is achieved by a permanently excited rotor for an electrical machine comprising a rotor body with a plurality of magnetic pockets for receiving permanent magnets, which are configured in such a way that they form rotor poles distributed over the circumference of the rotor body and alternately magnetically opposite, wherein a circular ring segment-like opening is formed in the rotor body at a radially outward distance from at least one magnetic pocket.

[0010] The permanent magnet rotor according to the invention thus allows for more efficient use of the magnetic properties of the permanent magnets. The arrangement of the magnetic pockets and the circular ring-segment-like openings ensures a uniform and effective magnetic field distribution.

[0011] This configuration also enables improved cooling of the rotor, for example by directing a cooling fluid through the channels defined by the circular ring-segment-like openings, which contributes to higher efficiency and reliability of the electric machine.

[0012] In a particularly preferred embodiment of the invention, it can be provided that adjacent magnetic pockets of a rotor pole in the circumferential direction are each separated from one another by a web extending in the radial direction, and that an annular segment-like opening is formed in the rotor body in radial alignment and radially outwardly spaced from at least one web. By implementing the annular segment-like opening radially and outwardly spaced from at least one web, an efficient reduction of the centrifugal force influences on the rotor body is also achieved. The consistent reduction in centrifugal force leads to a reduction in mechanical stress and thus to a reduction in rotor deformation at high speeds.This contributes significantly to meeting the mechanical requirements without negatively impacting the electromagnetic properties of the rotor and, consequently, the performance of the electric machine. This solution proves to be particularly advantageous from an economic perspective, as it enables a structurally simple and thus cost-effective improvement in the performance and operational reliability of the electric machine.

[0013] For the purposes of this patent application, a rotor body is a component of a permanently excited rotor for an electrical machine, which is specifically designed to contain a plurality of magnetic pockets for accommodating permanent magnets. These magnetic pockets are arranged such that they are distributed around the circumference of the rotor body and form alternating, magnetically opposing rotor poles. Furthermore, the rotor body is designed such that a circular ring-segment-like opening is formed in radial alignment and radially outwardly by at least one web. This opening serves to influence the magnetic flux properties and the mechanical properties of the rotor body.

[0014] The rotor body is designed to precisely accommodate the magnetic pockets required to house the permanent magnets, forming effective magnetic rotor poles. The webs between the magnetic pockets of a rotor pole provide mechanical stability and specifically influence the magnetic field within the rotor. The circular ring-segment-like openings formed in specific areas of the rotor body play a crucial role in reducing eddy current losses and improving the structural properties of the rotor by reducing the mechanical stresses on the webs while simultaneously optimizing the rotor's magnetic properties.

[0015] Preferred embodiments of the rotor body may vary in terms of the materials used and the design features. For example, materials such as steel alloys with high magnetic permeability or composite materials specifically developed for low density and high mechanical strength may be used.

[0016] The rotor body can preferably be formed from a rotor lamination stack. A rotor lamination stack is understood to be a plurality of laminated individual laminations or rotor laminations, usually made of electrical steel, which are stacked and stacked together to form a so-called rotor lamination stack. The individual laminations can then be held together in the lamination stack by gluing, welding, or screwing. A rotor lamination stack can, in particular, also have magnetic elements incorporated into the pockets of the rotor lamination stack or fixed circumferentially to the rotor lamination stack, as well as any axial cover parts for closing the pockets.

[0017] Furthermore, the annular segment-shaped openings and the arrangement of the magnetic pockets can be specifically adapted to optimize the performance and efficiency of the electric machine for specific applications. Advantageously, the features of the rotor body, such as the size and shape of the magnetic pockets as well as the arrangement and design of the annular segment-shaped openings, can be tailored to the specific requirements of the electric machine into which they are integrated. This includes, among other things, adaptations for different sizes of permanent magnets, different arrangements of rotor poles, and specific magnetic flux guides to ensure optimal performance of the electric machine. For the purposes of this patent application, an "annular segment-shaped opening" is defined as a structural element of the rotor body that forms part of a circular ring and is thus characterized by a curved boundary and two side edges.The side edges can preferably be curved in order to reduce mechanical stress peaks in the opening area. This gives the circular ring-segment-shaped opening a contour reminiscent of a curved banana. The circular ring-segment-shaped opening is preferably provided at a defined distance from the webs that separate the magnetic pockets from one another in the rotor body. The shape, size, and arrangement of the circular ring-segment-shaped opening are selected so that they are specifically designed to reduce mechanical loads and optimize the electromagnetic properties of the rotor. The circular ring-segment-shaped opening is preferably oriented so that the side edges point towards the outer surface of the rotor and the "belly" of the circular ring-segment-shaped opening points towards the axis of rotation of the rotor. The curved boundary of an opening can also be defined by a polygonal line.

[0018] The function of the circular segment-like opening primarily extends to the efficient reduction of centrifugal forces that arise at high rotor speeds. By removing material and the resulting mass reduction in the particularly stressed outer area of ​​the rotor, these forces are reduced. This advantageously results in reduced mechanical stress on the magnet holding bars and minimizes the risk of material fatigue or structural damage due to overloading.

[0019] In addition, the targeted arrangement of the circular-ring-segment-shaped opening, particularly preferably along the vector potential lines running in its vicinity for a pure q-current, enables the minimization of parasitic stray fluxes. This improves the electromagnetic behavior of the rotor by increasing the efficiency and effectiveness of the magnetic field and thus increasing the torque that can be generated by the machine. The design of the circular-ring-segment-shaped opening is based on the specific shape of a circular ring or a segment thereof and is characterized by a defined curvature and two side edges. The opening is positioned in the rotor body to ensure maximum effectiveness in fulfilling its mechanically relieving and electromagnetically optimizing function.Preferably, the circular ring segment-like opening is arranged at a uniform distance from the magnetic pockets and the webs in order to achieve a symmetrical effect and a balanced load distribution.

[0020] For the purposes of this patent application, a web is a structural element within the rotor body that extends radially between adjacent magnetic pockets. The web serves to physically separate these pockets, which contain permanent magnets for generating magnetic rotor poles. The webs are configured to not only provide structural support but also contribute to influencing the electromagnetic properties of the rotor.

[0021] The function of the web encompasses several essential aspects for the integrity and performance of the rotor. First, the web ensures a clearly defined physical separation of the magnetic pockets. This separation is crucial to ensure correct magnetic alignment and thus optimal performance of the electric machine. Second, the web contributes to the mechanical stability of the rotor by acting as a support element between the magnetic pockets, thus counteracting the stress caused by centrifugal forces, which can be particularly significant at high speeds. Third, through its positioning and dimensioning, the web can influence the stray fluxes between the magnetic pockets and thus indirectly affect the efficiency of the machine.

[0022] The design of the web is characterized by its preferably essentially linear extension in the radial direction from the inner to the outer diameter of the rotor body. The webs are preferably manufactured monolithically from the same material as the rotor body in order to guarantee uniform mechanical and thermal load-bearing capacity. The dimensions of the webs, in particular their width and height, are tailored to the specific requirements of the design and the electromagnetic efficiency. For example, the width of the webs can be adjusted to modulate the magnetic flux between the magnetic pockets and thus optimize the behavior of the machine under different operating conditions. Advantageously, the webs are designed to provide effective support for the rotor, but at the same time support the electromagnetic properties of the machine by minimally affecting the magnetic fields.

[0023] The magnetic pockets can preferably comprise leakage barriers. For the purposes of this application, leakage flux barriers are design features that help reduce magnetic leakage flux and improve the performance of the electrical machine. They help concentrate the magnetic flux of the permanent magnets directly onto the stator winding, thereby increasing magnetic coupling and thus the efficiency of the electrical machine. By preferentially interrupting the magnetic flux between the poles, the leakage flux barriers also reduce the leakage flux and thus minimize the magnetic losses in the rotor. Since the leakage flux barriers can thus help reduce magnetic losses, they also contribute to reducing the temperature in the rotor during operation, which can increase the service life and reliability of the electrical machine.Leakage flux barriers are preferably made of non-magnetic materials such as plastic, ceramic, or aluminum, which interrupt the magnetic field and direct the magnetic flux within a rotor segment in a desired direction. A leakage flux barrier can also be formed, for example, from a ceramic such as ferrite or aluminum oxide. Furthermore, it is possible for a leakage flux barrier to be made of a plastic such as polytetrafluoroethylene (PTFE) or polyetheretherketone (PEEK). In principle, it is also conceivable for a leakage flux barrier to be made of air or to be designed as an air-filled cavity. The leakage flux barriers are advantageously positioned in the rotor segment near the permanent magnets. The shape and size of the leakage flux barriers depend on the specific application and the desired magnetic flux path within a rotor segment.Rotor magnets are arranged in the magnetic pockets of the rotor body. The term "rotor magnet" refers to the permanent magnets that are inserted into the pockets of the rotor body. A single, larger rotor magnet designed as a bar magnet or several smaller permanent magnet elements can be provided per pocket. Neodymium iron boron (NdFeB) or samarium cobalt (SmCo) are preferably used to form the rotor magnets. The rotor magnets are preferably fixed in the magnetic pockets with a material bond, for example, using an adhesive.

[0024] According to an advantageous embodiment of the invention, a circular ring-segment-like opening can be formed on a plurality of, preferably all, webs between the magnetic pockets of a rotor pole. This leads to a uniform distribution of the resulting forces and thus to a significant reduction in the mechanical loads on the rotor, in particular on the magnetic holding webs. The uniform force distribution results in improved mechanical stability and an increased service life of the rotor, especially during speed peaks. From an economic perspective, this is particularly advantageous, as it reduces maintenance costs and the overall operating costs of the electric machine. The circular ring-segment-like openings can also contribute to a more uniform temperature distribution within the rotor, thereby reducing the risk of thermally induced material fatigue.

[0025] The electromagnetic field in electrical machines is often described using vector potentials, as these provide an effective way to analyze the spatial distribution and dynamics of magnetic fields. The vector potential is a vector field from which the magnetic field can be derived by its rotation. In permanent-magnet synchronous machines, the stator winding is traversed by a so-called q-current, which flows transversely (perpendicular to the rotor axis) to the magnetic axis of the permanent magnets in the rotor. This current generates a magnetic field, which is primarily responsible for generating the machine's torque.

[0026] According to a further preferred development of the invention, it can also be provided in this context that an opening in the shape of a circular ring extends along the vector potential lines running in its vicinity for a pure q-current, thereby further improving the magnetic efficiency of the rotor. By aligning the opening along the vector potential lines, the performance of the rotor can be optimized, as this leads to a reduction in magnetic stray losses. Such a specific design contributes to reducing magnetic saturation in certain areas of the rotor, which leads to an improvement in the dynamic response characteristics of the electrical machine. This approach is therefore particularly suitable for high-performance applications where fast response and high efficiency are important.The geometric shape and positioning of the opening were deliberately chosen to replicate or support the natural course of the magnetic field lines generated by the q-current. The specific arrangement of the circular opening along the vector potential lines for a pure q-current achieves an optimal compromise between mechanical stress relief and the minimization of parasitic electromagnetic effects. This arrangement makes it possible to minimize parasitic stray fluxes and thus increase the efficiency and torque of the electric machine. A further advantage arises from the optimization of the reluctance torque, which leads to improved power density and optimized operating behavior.From an economic point of view, this solution offers the advantage of increasing the performance of the electric machine without costly materials or complex manufacturing processes.

[0027] The goal of this special arrangement of the annular segment-like opening is to maximize the efficiency of torque generation and minimize unwanted parasitic effects. By placing the opening along the vector potential lines for a pure q-current, the magnetic field lines are influenced in a way that supports the formation of the desired magnetic field, thus optimizing the torque and overall performance of the machine. The shape and arrangement of these openings can help reduce disturbances in the magnetic field caused by the opening. This minimizes stray flux and improves the efficiency of the machine by concentrating magnetic energy where it is most effective for torque generation.Furthermore, according to a likewise advantageous embodiment of the invention, it can be provided that the magnetic pockets of a rotor pole are arranged along a first, radially inner cross-sectional contour and / or a second, radially outer cross-sectional contour. This arrangement makes it possible to design the rotor so that it can be optimized for different torques and speeds. The ability to precisely control the positioning of the permanent magnets allows the efficiency of the machine to be optimized over a wide operating range. Furthermore, a rotor designed in this way offers the advantage of an optimized arrangement of the magnetic pockets, which enables more efficient use of the available space in the rotor body. By arranging the magnetic pockets along different radial cross-sectional contours, a denser packing of the magnets and thus an increase in the magnetic power density can be achieved.This leads to an improvement in the electromagnetic design and a corresponding increase in the torque that can be generated.

[0028] According to a further particularly preferred embodiment of the invention, it can be provided that an annular segment-like opening is formed in the rotor body between the magnet pockets of the first cross-sectional contour in the radial direction and spaced radially outwards from a web and / or an annular segment-like opening is formed in the rotor body between the magnet pockets of the second cross-sectional contour in the radial direction and spaced radially outwards from a web.

[0029] The formation of circular ring-segment-like openings that are radially aligned and spaced radially outward from a web in the rotor body. This differentiated arrangement enables a more effective reduction of mechanical loads and an optimization of the electromagnetic flux, which leads to improved functionality and increased efficiency of the electric machine. Furthermore, this configuration enables adaptation to various operating conditions and requirements, thus expanding the range of applications of the electric machine. Furthermore, the invention can also be further developed such that the width of the webs between the magnetic pockets of the first cross-sectional contour is smaller than the width of the webs between the magnetic pockets of the second cross-sectional contour.The differentiation in the width of the webs between the magnetic pockets of the first and second cross-sectional contours offers the advantage of a targeted influence on the magnetic and mechanical properties of the rotor. By varying the web width, the magnetic coupling between adjacent rotor poles can be fine-tuned, which leads to a further optimization of the performance of the electric machine. This targeted adjustment makes it possible to minimize iron losses and optimize efficiency, especially at different operating frequencies. The targeted control of the web widths also enables the optimization of mechanical stability and deformation resistance in critical areas of the rotor, while simultaneously maximizing electrical performance through an adapted distribution of the magnetic fields.

[0030] In a likewise preferred embodiment of the invention, it can also be provided that a circular segment-like opening assigned to a web of the first cross-sectional contour has a smaller arc angle than a circular segment-like opening assigned to a web of the second cross-sectional contour. The specific design of circular segment-like openings with different arc angles, depending on their assignment to the webs of the first or second cross-sectional contour, represents a further optimization option for magnetic efficiency. By adjusting the arc angles, the stray flux distribution in the rotor can be precisely influenced, which leads to optimal use of the magnetic material. Furthermore, this embodiment also enables finely tuned adjustment of the mechanical load relief of the rotor body.

[0031] It may also be advantageous to further develop the invention such that the first cross-sectional contour and / or the second cross-sectional contour extend along a convex function, which realizes the advantage of an optimized magnetic path length for the magnetic flux. According to a further preferred embodiment of the subject matter of the invention, it can be provided that at least three magnetic pockets are arranged along the first cross-sectional contour and / or at least three magnetic pockets are arranged along the second cross-sectional contour. This configuration enables homogeneous magnetization of the rotor, which leads to a more uniform torque development and an increase in the overall power of the electric machine.

[0032] Finally, the object of the invention can also be achieved by an electric machine, in particular for a drive train of an electrically driven motor vehicle, comprising a permanently excited rotor according to claim 1. The use of a permanently excited rotor as described in claim 1 in an electric machine, in particular for a drive train of an electrically driven motor vehicle, offers the decisive advantage of high energy efficiency and power density. The specific design of the rotor, in particular by optimizing the magnetic and mechanical properties, achieves greater efficiency, power density, and reliability of the electric machine. This leads to improved performance, reduced energy consumption, and a longer service life of the drive system.From an economic point of view, this is particularly attractive as it leads to a reduction in operating and maintenance costs and increases the attractiveness of the motor vehicle for the end consumer.

[0033] The invention will be explained in more detail below with reference to figures without limiting the general inventive concept.

[0034] It shows:

[0035] Figure 1 is a cross-sectional view of an electrical machine known from the prior art,

[0036] Figure 2 shows a detailed representation of a rotor pole of a permanent magnet rotor known from the prior art in a cross-sectional view, Figure 3 shows a detailed representation of a rotor pole of a first embodiment of a permanent magnet rotor in a cross-sectional view,

[0037] Figure 4 shows a detailed representation of a rotor pole of a second embodiment of a permanently excited rotor in a cross-sectional view,

[0038] Figure 5 shows a detailed representation of a rotor pole of the second embodiment of a permanent magnet rotor with vector potential lines in a cross-sectional view,

[0039] Figure 6 shows a detailed representation of a rotor pole of the second embodiment of a permanent magnet rotor with magnetic flux paths in a cross-sectional view,

[0040] Figure 7 shows a detailed representation of a circular segment-like opening in a cross-sectional view,

[0041] Figure 8 shows a third embodiment of a permanent magnet rotor in a cross-sectional view and a detailed view,

[0042] Figure 9 shows a fourth embodiment of a permanent magnet rotor in a cross-sectional view and a detailed view,

[0043] Figure 10 shows a motor vehicle with an electrically operated drive train in a schematic representation.

[0044] Figure 1 shows a cross-sectional view of an electrical machine 2 known from the prior art. The electrical machine 2 is designed as a radial flux machine with an internally rotating rotor 1. The energizable stator windings 14 are embedded in the circumferentially distributed stator slots 13 of the stator body 12. The rotor 1 is designed as a permanent magnet excited rotor 1, comprising a rotor body 3 with a plurality of magnetic pockets 4 for receiving permanent magnets 5, which are configured such that they form rotor poles 6 distributed over the circumference of the rotor body 3 and alternatingly magnetically opposite, which is indicated in Figure 1 by the circles and their north / south pole magnetization.

[0045] As can be seen from Figure 2, circumferentially adjacent magnetic pockets 4 of a rotor pole 6 are each separated from one another by a web 7 extending in the radial direction.

[0046] Figures 1-2 show a configuration of a permanent magnet rotor 1 already known from the prior art. An embodiment of a rotor 1 according to the invention is shown in Figure 3. In this embodiment, the magnetic pockets 4 of a rotor pole 6 are arranged along a first, radially inner cross-sectional contour 9 and a second, radially outer cross-sectional contour 10. This first cross-sectional contour 9 and the second cross-sectional contour 10 each run along a convex function. Figure 3 also shows that three magnetic pockets 4a are arranged along the first cross-sectional contour 9 and three magnetic pockets 4b are arranged along the second cross-sectional contour 10.

[0047] Between the magnet pockets 4a of the first cross-sectional contour 9, a circular ring-segment-like opening 8a is formed in the rotor body 3, radially aligned and spaced radially outward from a web 7a. Figure 4 shows an embodiment in which an additional circular ring-segment-like opening 8b is formed in the rotor body 3 between the magnet pockets 4b of the second cross-sectional contour 10, radially aligned and spaced radially outward from a web 7b.

[0048] Figure 4 further shows that the width of the webs 7a between the magnetic pockets 4a of the first cross-sectional contour 9 is smaller than the width of the webs 7b between the magnetic pockets 4b of the second cross-sectional contour 10. What can also be seen from Figure 4 is that a circular segment-like opening 8a assigned to a web 7a of the first cross-sectional contour 9 has a smaller arc angle 11 than a circular segment-like opening 8b assigned to a web 7b of the second cross-sectional contour 10. The arc angle 11 is also shown in Figure 6.

[0049] Figures 3-4 also clearly show that the circular ring-segment-like openings 8 extend essentially parallel to the cross-sectional contours 10. Thus, the openings 8 point with their respective ends toward the outer surface of the rotor 1.

[0050] As can be further seen from Figure 5, a circular opening 8 extends along the vector potential lines 15 running in its vicinity for a pure q-current and non-magnetized permanent magnets 5. This arrangement significantly reduces "stray losses" because the opening 8 runs along the vector potential lines 15 and thus prevents a narrowing of the flux paths. This contributes to the efficiency and performance of the electrical machine.

[0051] 2. Figure 6 shows the relevant flux paths for the torque generated by permanent magnets in the rotor 1 of an electrical machine 2. This is indicated by the hatched areas and the arrows in Figure 6. It is clearly visible that the arc length or arc angle 11 of the positioned openings 8 in the rotor body 3 is configured such that the flux paths are not significantly constricted. This ensures optimal flux distribution and also minimizes losses due to magnetic field straying. The precise configuration of the openings 8 ensures efficient power delivery of the electrical machine 2.

[0052] Figure 7 shows the geometrical and structural details of the rotor body

[0053] 3. The magnetic pockets 4 have a substantially rectangular basic contour, whereby flux-guiding contours can be formed on the short sides, so that these deviate from a rectangular shape, as can be seen, for example, in the embodiments of Figures 2-5. The circular ring-segment-like opening 8 is aligned centrally with respect to the radial axis 16 and sweeps an arc angle 11 whose center lies on the radial axis 16. The web 7 is also aligned centrally with respect to the radial axis 16.

[0054] The arc angle 11 divides the cross-sectional areas of the permanent magnets 5 arranged in the magnetic pockets 4 into the areas 18 lying within the angle legs of the arc angle 11 and the areas 17 lying outside the angle legs. The sum of the areas 18 lying within the angle legs of the arc angle 11 is greater than the sum of the areas 17 lying outside the angle legs of the arc angle 11. In this context, it is particularly preferred if the sum of the areas 18 lying within the angle legs of the arc angle 11 is at least twice as large as the sum of the areas 17 lying outside the angle legs of the arc angle 11.

[0055] Figures 8 and 9 show further embodiments of a rotor 1 according to the invention. Here, the rotors 1 have a configuration of the magnetic pockets 4 that differs from that in the previous embodiments, which can also be referred to as a V-shaped magnetic pocket configuration, with a V-shaped magnetic pocket arrangement forming a rotor pole 6 of the rotor 1. Figures 8-9 also clearly show that the circular ring-segment-like opening 8 can also be defined as a polygonal line consisting of several straight lines. Otherwise, with regard to the function of the openings 8 and the webs 7, reference is made to the previous embodiments.

[0056] Finally, Figure 10 shows that the electric machine 2 can be used in a drive train 20 of an electrically driven motor vehicle 21.

[0057] The invention is not limited to the embodiments illustrated in the figures. The above description is therefore not to be considered restrictive, but rather explanatory. The following claims are to be understood as meaning that a stated feature is present in at least one embodiment of the invention. This does not exclude the presence of further features. Where the claims and the above description define 'first' and 'second' features, this designation serves to distinguish between two similar features without establishing a priority. List of reference symbols

[0058] 1 rotor

[0059] 2 electric machine

[0060] 3 rotor bodies

[0061] 4 magnetic pockets

[0062] 5 permanent magnets

[0063] 6 rotor poles

[0064] 7 jetty

[0065] 8 Opening

[0066] 9 Cross-sectional contour

[0067] 10 Cross-sectional contour

[0068] 11 arc angle

[0069] 12 Stator body

[0070] 13 stator slots

[0071] 14 Stator winding

[0072] 15 vector potential lines

[0073] 16 Radial axis

[0074] 17 Area section

[0075] 18 Area section

[0076] 20 Drivetrain

[0077] 21 Motor vehicle

Claims

Claims 1. Permanent magnet excited rotor (1) for an electrical machine (2) comprising a rotor body (3) with a plurality of magnetic pockets (4) for receiving permanent magnets (5), which are configured in such a way that they form rotor poles (6) distributed over the circumference of the rotor body (3) and alternately magnetically opposite, wherein circumferentially adjacent magnetic pockets (4) of a rotor pole (6) are each separated from one another by a web (7) extending in the radial direction, characterized in that an opening (8) in the form of a circular ring segment is formed in the rotor body (3) at a radially outwardly spaced distance from at least one magnet pocket (4).

2. Rotor (1) according to claim 1, characterized in that circumferentially adjacent magnetic pockets (4) of a rotor pole (6) are each separated from one another by a web (7) extending in the radial direction, and an opening (8) in the form of a circular ring segment is formed in the rotor body (3) in radial alignment and spaced radially outwards from at least one web (7).

3. Rotor (1) according to claim 2, characterized in that an annular segment-like opening (8) is formed on a plurality of, preferably on all, webs (7) between the magnetic pockets (4) of a rotor pole (6).

4. Rotor (1) according to one of the preceding claims, characterized in that an annular opening (8) extends along the vector potential lines running in its surroundings for a pure q-current.

5. Rotor (1) according to one of the preceding claims, characterized in that the magnetic pockets (4) of a rotor pole (6) are arranged along a first, radially inner cross-sectional contour (9) and / or a second, radially outer cross-sectional contour (10).

6. Rotor (1) according to one of the preceding claims 2-5, characterized in that an annular segment-like opening (8a) is formed in the rotor body (3) between the magnet pockets (4a) of the first cross-sectional contour (9) in the radial direction, aligned and radially outwardly spaced from a web (7a), and / or an annular segment-like opening (8b) is formed in the rotor body (3) between the magnet pockets (4b) of the second cross-sectional contour (10) in the radial direction, aligned and radially outwardly spaced from a web (7b).

7. Rotor (1) according to claim 5 or 6, characterized in that the width of the webs (7a) between the magnetic pockets (4a) of the first cross-sectional contour (9) is smaller than the width of the webs (7b) between the magnetic pockets (4b) of the second cross-sectional contour (10).

8. Rotor (1 ) according to one of claims 5-7, characterized in that a circular segment-like opening (8a) associated with a web (7a) of the first cross-sectional contour (9) has a smaller arc angle (11 ) than a a circular segment-like opening (8b) associated with a web (7b) of the second cross-sectional contour (10) 9. Rotor (1) according to one of claims 5-8, characterized in that the first cross-sectional contour (9) and / or the second cross-sectional contour (10) runs along a convex function.

10. Rotor (1) according to one of claims 5-9, characterized in that at least three magnetic pockets (4a) are arranged along the first cross-sectional contour (9) and / or at least three magnetic pockets (4b) are arranged along the second cross-sectional contour (10).

11. Electrical machine (2), in particular for a drive train (20) of an electrically driven motor vehicle (21), comprising a permanently excited rotor (1) according to claim 1.

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