Permanent magnet excited 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 accommodating slots (4) for accommodating permanent magnets (5), which are configured to form alternating magnetically opposite rotor poles (6) distributed in the circumferential direction of the rotor body (3), wherein each two of the circumferentially adjacent magnet accommodating slots (4) of a rotor pole (6) are separated from each other by a radially extending bridge (7), respectively, wherein an opening (8) in the form of a circular ring segment is formed in the rotor body (3), which is radially aligned with and spaced radially outward from at least one bridge (7).

Description

Technical Field

[0001] This invention relates to a permanent magnet driven rotor for an electric motor, comprising a rotor body having a plurality of magnet receiving slots for accommodating permanent magnets, the magnet receiving slots being configured to form rotor poles arranged circumferentially along the rotor body and alternately magnetized in opposite directions, wherein circumferentially adjacent magnet receiving slots of a rotor pole are separated from each other by a radially extending bridge. The invention also relates to an electric motor. Background Technology

[0002] Existing technologies in the field of permanent magnet driven rotors for electric motors include various developments aimed at optimizing the performance, efficiency, and operational reliability of these components. Permanent magnet driven rotors utilize permanent magnets positioned in specially designed slots within the rotor body to generate a permanent magnetic field, which interacts with the electric field generated by the stator to produce the motor's torque.

[0003] A core issue with permanent magnet driven rotors is mechanical load, especially at high speeds. Centrifugal forces acting on rotor components, particularly on the permanent magnets and surrounding structures such as magnet housings and bridges, can cause plastic deformation or even failure. Such loads significantly impact machine reliability and lifespan, thus posing a major technical challenge.

[0004] Another significant problem associated with permanent magnet driven rotors is the limitation of electromagnetic efficiency caused by parasitic effects. These parasitic effects include undesirable leakage flux that can reduce torque generation efficiency. The specific configuration and arrangement of the permanent magnets and bridges in the rotor have a decisive influence on these leakage fluxes. In particular, unoptimized arrangement and sizing of these components can lead to performance degradation, thereby limiting the motor's efficiency and power density.

[0005] Simultaneously satisfying both mechanical and electromagnetic requirements reflects a significant bottleneck in existing technologies. While conventional solutions, such as modifying the bridge or magnet housing configuration, can improve aspects like mechanical stability, they often compromise electromagnetic performance. In particular, reducing mass in critical areas of the rotor to reduce centrifugal loads has proven detrimental to generating effective torque, as this can have undesirable effects on the magnetic field and consequently on machine efficiency.

[0006] Therefore, the object of the present invention is to eliminate or at least mitigate the problems known in the prior art and to provide a correspondingly improved permanent magnet excitation rotor for an electric motor. Another object of the present invention is to realize an optimized electric motor. Summary of the Invention

[0007] This task is solved by a permanent magnet excitation rotor for an electric motor, which includes a rotor body having a plurality of magnet receiving slots for accommodating permanent magnets, the magnet receiving slots being configured to form rotor poles that are circumferentially distributed along the rotor body and alternately magnetized in opposite directions, wherein an annular segmental opening is formed in the rotor body that is radially outwardly spaced from at least one magnet receiving slot.

[0008] The permanent magnet excitation rotor according to the invention thus allows for more efficient utilization of the magnetic properties of the permanent magnet. The arrangement of the magnet receiving slots and the annular segmental openings ensures a uniform and effective magnetic field distribution.

[0009] This configuration also enables improved rotor cooling, for example by allowing coolant to flow through channels defined by annular segmental openings, which helps improve the efficiency and reliability of the motor.

[0010] In a particularly preferred embodiment of the invention, adjacent circumferentially oriented magnet receiving slots of a rotor pole are separated by a radially extending bridge portion, and an annular segmental opening is formed in the rotor body that is radially aligned with and radially spaced outward from at least one bridge portion. By implementing the annular segmental openings that are radially spaced outward relative to at least one bridge portion, the effect of centrifugal force acting on the rotor body is also effectively reduced. This consistent reduction in centrifugal force leads to a decrease in mechanical load, thereby reducing rotor deformation at high speeds. This makes a significant contribution to meeting mechanical requirements without negatively impacting the electromagnetic characteristics of the rotor and, consequently, the performance of the motor. From an economic perspective, this solution is particularly advantageous because it improves motor performance and operational reliability in a simple and therefore cost-effective manner.

[0011] In the context of this patent application, the rotor body is a component of the permanent magnet driven rotor of an electric motor, specifically designed to include multiple magnet receiving slots for accommodating permanent magnets. These magnet receiving slots are designed to be distributed circumferentially along the rotor body and form alternating rotor poles with opposite magnetic properties. Furthermore, the rotor body is designed to form an annular segmental opening radially aligned with at least one bridge portion and radially outward. This opening influences the magnetic flux characteristics and mechanical properties of the rotor body.

[0012] The rotor body is designed to include magnet receiving slots necessary to accommodate permanent magnets, precisely arranged to form effective magnetic rotor poles. Bridges between the magnet receiving slots of a rotor pole serve for mechanical stability and to influence the orientation of the magnetic field within the rotor. Annular segmental openings formed in specific regions of the rotor body play a decisive role in reducing eddy current losses and improving the rotor's structural characteristics by decreasing the mechanical load on the bridges and simultaneously optimizing the rotor's magnetic properties.

[0013] Preferred embodiments of the rotor body may vary in terms of the materials used and construction features. For example, steel alloys with high magnetic permeability or composite materials specifically developed for low density and high mechanical strength may be used.

[0014] The rotor body is preferably formed from a rotor lamination assembly. A rotor lamination assembly is understood as a plurality of laminated single pieces, typically made of electrical steel sheets, i.e., rotor steel sheets, stacked on top of each other to form a stack, the so-called rotor lamination assembly, and assembled into a package. Subsequently, the single pieces can be held together within the lamination assembly by bonding, welding, or screwing. The rotor lamination assembly may also particularly have magnetic elements introduced into slots within the rotor lamination assembly or magnetic elements fixed circumferentially to the rotor lamination assembly, and existing axial covers for closing the slots when needed.

[0015] Furthermore, the arrangement of the annular segmental openings and magnet receiving slots can be specifically adjusted to optimize motor performance and efficiency for particular applications. Advantageously, features of the rotor body, such as the size and shape of the magnet receiving slots and the arrangement and design of the annular segmental openings, can be customized to the specific requirements of the motor into which they are integrated. This includes, in particular, adjustments for different sizes of permanent magnets, different rotor pole arrangements, and specific flux guidance to ensure optimal motor performance.

[0016] In the context of this patent application, an "annular segmental opening" is defined as a structural element of the rotor body, forming part of an annular structure and thus having a curved boundary and two sides. The sides are preferably formed in an arc shape to reduce peak mechanical stress in the opening region. Thus, the annular segmental opening acquires a profile reminiscent of a curved banana. The annular segmental opening is preferably located within the rotor body at a distance from the bridge separating the magnet receiving slots. The shape, size, and arrangement of the annular segmental opening are selected to specifically reduce mechanical loads and optimize the electromagnetic characteristics of the rotor. Preferably, the annular segmental opening is oriented so that the sides point towards the outer circumferential surface of the rotor, and the "belly" of the annular segmental opening points towards the rotational axis of the rotor. The curved boundary of an opening may also be defined by a broken line.

[0017] The annular segmental opening primarily functions to efficiently reduce the centrifugal forces generated at high rotor speeds. This reduction is achieved by removing material and consequently reducing mass in the outer regions of the rotor where loads are particularly high. Advantageously, this results in reduced mechanical loads on the magnet retaining bridge and minimizes the risk of material fatigue or structural damage due to overload.

[0018] Furthermore, the directional arrangement of the annular segmental opening, particularly preferably along a vector potential line extending around it for a pure q-current, minimizes parasitic leakage flux. This improves the electromagnetic behavior of the rotor by increasing the efficiency and effectiveness of the magnetic field, and thus increases the torque that the machine can produce.

[0019] The structure of the annular segmental opening is based on a specific shape of an annular body or a portion thereof, and is characterized by a defined curvature and two sides. This opening is positioned within the rotor body to provide maximum effectiveness in achieving its mechanical unloading and electromagnetic optimization functions. Preferably, the annular segmental opening is arranged at a uniform distance from the magnet receiving slot and the bridge section to achieve symmetrical action and balanced load distribution.

[0020] In the context of this patent application, the bridge is a structural element within the rotor body that extends radially between adjacent magnet-receiving slots. The bridge serves to physically separate these slots, which house permanent magnets used to generate magnetic rotor poles. The bridge is configured not only to function as structural support but also to contribute to influencing the electromagnetic characteristics of the rotor.

[0021] The bridge section functions in several ways that are crucial to the integrity and performance of the rotor. First, the bridge provides a clearly defined physical separation between the magnet housing slots. This separation is essential for ensuring proper magnetic orientation and thus optimal motor performance. Second, the bridge contributes to the rotor's mechanical stability by acting as a support element between the magnet housing slots, thereby resisting loads caused by centrifugal forces, which can be particularly significant at high speeds. Third, the bridge, through its positioning and dimensional design, can influence the leakage flux between the magnet housing slots, indirectly affecting the machine's efficiency.

[0022] The bridge section is structurally characterized by its preferably radially linear extension from the inner radial diameter of the rotor body. Preferably, the bridge section is integrally constructed of the same material as the rotor body to ensure uniform mechanical and thermal load-bearing capacity. The dimensions of the bridge section, particularly its width and height, are matched to specific requirements of construction and electromagnetic efficiency. For example, the width of the bridge section can be adjusted to modulate the magnetic flux between the magnet receiving slots, thereby optimizing the machine's behavior under different operating conditions. Advantageously, the bridge section is designed to provide effective support for the rotor while supporting the machine's electromagnetic characteristics with minimal disturbance to the magnetic field.

[0023] The magnet receiving slot may preferably include a leakage magnetic barrier. In the sense of this application, a leakage magnetic barrier is a structural feature that helps reduce magnetic leakage flux and improve motor performance. They help to directly concentrate the magnetic flux of the permanent magnet onto the stator windings, thereby increasing magnetic coupling and thus improving motor efficiency. By preferably interrupting the magnetic flux between the poles, the leakage magnetic barrier also reduces leakage flux and thereby minimizes magnetic losses in the rotor. Since the leakage magnetic barrier thus helps reduce magnetic losses, it also helps reduce the temperature in the rotor during operation, which can improve the expected lifespan and reliability of the motor. The leakage magnetic barrier is preferably composed of a non-magnetic material, such as plastic, ceramic, or aluminum, whereby the magnetic field is interrupted and the magnetic flux within the rotor segment can be guided in the desired direction. The leakage magnetic barrier may also be formed of ceramic, such as ferrite or alumina. Furthermore, the leakage magnetic barrier may also be made of plastic, such as polytetrafluoroethylene (PTFE) or polyetheretherketone (PEEK). In principle, it is also conceivable that the leakage magnetic barrier is made of air or constructed as an air-filled cavity. The leakage magnetic barrier is advantageously positioned in the rotor segment close to the permanent magnet. The shape and size of the leakage magnetic barrier depend on the specific application and the desired magnetic flux path within the rotor section.

[0024] Rotor magnets are arranged in magnet receiving slots within the rotor body. The rotor magnets are understood as permanent magnets to be placed into the rotor body slots. In this case, each slot may be provided with a larger rotor magnet composed of a rod magnet, or with rotor magnets composed of multiple smaller permanent magnet elements. Neodymium iron boron (NdFeB) or samarium cobalt (SmCo) is preferably used to form the rotor magnets. The rotor magnets are preferably fixed in the magnet receiving slots by a material bonding method, such as using adhesives.

[0025] According to an advantageous design of the invention, the annular segmental openings are formed at multiple bridge sections, preferably at all bridge sections, between the magnet receiving slots of a rotor pole. This results in a uniform distribution of the generated forces, thereby significantly reducing the mechanical load applied to the rotor, especially to the magnet retaining bridge sections. The uniform force distribution leads to improved mechanical stability and increased rotor life, especially under peak speed conditions. From an economic perspective, this is particularly advantageous because it reduces maintenance costs and lowers the overall operating cost of the motor. The annular segmental openings also contribute to a more uniform temperature distribution within the rotor, thereby reducing the risk of thermally induced material fatigue.

[0026] Electromagnetic fields in electric motors are typically described using vector potentials because they provide an efficient way to analyze the spatial distribution and dynamics of magnetic fields. A vector potential is a vector field whose magnetic field can be derived from its curl. In a permanent magnet synchronous motor, a so-called q-current flows through the stator windings, which flows transversely (transverse to the rotor axis) across the magnetic axis of the permanent magnets in the rotor. The magnetic field generated by this current is primarily responsible for producing the machine's torque.

[0027] According to another preferred improvement of the invention, in this context, an annular segmental opening may also be specified to extend around it along a vector potential line extending for the pure q current, thereby further improving the magnetic efficiency of the rotor. By orienting the opening along the vector potential line, the rotor performance can be optimized because this results in a reduction in magnetic leakage loss. This specific design helps to reduce magnetic saturation in certain regions of the rotor, thereby improving the dynamic response characteristics of the motor. Therefore, this solution is particularly suitable for high-performance applications requiring fast response and high efficiency. Thus, the geometry and positioning of the opening are deliberately chosen to follow or support the natural orientation of the magnetic field lines generated by the q current. Thus, by specifically arranging the annular opening along the vector potential line of the pure q current, an optimal trade-off is achieved between mechanical unloading and minimizing parasitic electromagnetic effects. This arrangement minimizes parasitic leakage flux, thereby improving the efficiency and torque of the motor. Another advantage comes from the optimization of reluctance torque, which leads to improved power density and optimized operating behavior. From an economic perspective, the advantage of this solution is that it improves motor performance without requiring expensive materials or complex manufacturing processes.

[0028] The specific arrangement of these annular segmented openings aims to maximize torque generation efficiency and minimize undesirable parasitic effects. By arranging the openings along the vector potential line of a pure q-current, the goal is to influence the magnetic field lines in a way that supports the formation of the desired magnetic field, thereby optimizing the machine's torque and overall performance. The shape and arrangement of these openings help reduce magnetic field disturbances caused by the openings. This results in minimized leakage flux and improved machine efficiency, as magnetic energy is concentrated at its most effective location for torque generation.

[0029] Furthermore, according to another equally advantageous design of the invention, the magnet receiving slots of one rotor pole can be arranged along a first radially inner cross-sectional profile and / or a second radially outer cross-sectional profile. This arrangement allows the rotor to be designed to be optimized for different torques and speeds. By precisely controlling the positioning of the permanent magnets, machine efficiency can be optimized over a wide operating range. Moreover, a rotor configured in this way also has the advantage of an optimized magnet receiving slot arrangement, which allows for more efficient use of available space within the rotor body. By arranging the magnet receiving slots along different radial cross-sectional profiles, a denser magnet arrangement can be achieved, thus increasing the magnetic power density. This leads to improved electromagnetic design and, consequently, increased torque.

[0030] According to another particularly preferred embodiment of the present invention, it may be specified that an annular segmental opening is formed in the rotor body between the magnet receiving grooves of the first cross-sectional profile, which is radially aligned with and radially spaced apart from the bridge portion, and / or an annular segmental opening is formed in the rotor body between the magnet receiving grooves of the second cross-sectional profile, which is radially aligned with and radially spaced apart from the bridge portion.

[0031] An annular segmental opening is formed within the rotor body, radially aligned with and radially spaced outward from the bridge section. This differentiated arrangement achieves more effective reduction of mechanical load and optimization of electromagnetic flux, resulting in improved functionality and increased efficiency of the motor. Furthermore, this configuration can adapt to different operating conditions and requirements, thereby expanding the motor's application range.

[0032] Furthermore, the invention can be further developed such that the bridge width between the magnet receiving slots of the first cross-sectional profile is smaller than the bridge width between the magnet receiving slots of the second cross-sectional profile. This difference in bridge width between the magnet receiving slots of the first and second cross-sectional profiles provides the advantage of selectively influencing the magnetic and mechanical characteristics of the rotor. By changing the bridge width, the magnetic coupling between adjacent rotor poles can be finely adjusted, thereby further optimizing motor performance. This directional adjustment enables the minimization of iron losses and, particularly, the optimization of efficiency at different operating frequencies. The directional control of the bridge width also enables the optimization of mechanical stability and resistance to deformation in critical areas of the rotor, while maximizing electrical performance through an adaptive distribution of the magnetic field.

[0033] In another equally preferred design variant of the invention, it may be specified that an annular segmental opening associated with the bridge portion of the first cross-sectional profile has a smaller arc angle than an annular segmental opening associated with the bridge portion of the second cross-sectional profile. The specific design of the annular segmental openings with different arc angles, depending on their association with the bridge portion of the first or second cross-sectional profile, provides the possibility of further optimizing magnetic efficiency. By adjusting the arc angle, the leakage flux distribution in the rotor can be precisely affected, thereby achieving optimal utilization of the magnetic material. Furthermore, this implementation variant also enables fine adjustment of the mechanical unloading of the rotor body.

[0034] Furthermore, it is advantageous to further develop the invention so that the first cross-sectional profile and / or the second cross-sectional profile extend along a convex function, which achieves the advantage of optimized magnetic circuit length of magnetic flux.

[0035] According to another preferred design of the present invention, at least three magnet receiving slots may be arranged along a first cross-sectional profile and / or at least three magnet receiving slots may be arranged along a second cross-sectional profile. This configuration achieves uniform magnetization of the rotor, thereby resulting in more uniform torque development and improved overall motor performance.

[0036] Finally, the objective of this invention can also be achieved by an electric motor, particularly for a powertrain system of an electric vehicle, comprising a permanent magnet driven rotor as claimed in claim 1. Applying the permanent magnet driven rotor as claimed in claim 1 to an electric motor, particularly to the powertrain system of an electric vehicle, offers the key advantages of high energy efficiency and high power density. Through specific design of the rotor, especially by optimizing magnetic and mechanical properties, higher efficiency, power density, and motor reliability are achieved. This results in improved performance, reduced energy consumption, and extended drive system lifespan. From an economic perspective, this is particularly attractive because it leads to lower operating and maintenance costs and increases the attractiveness of the vehicle to end users. Attached Figure Description

[0037] The present invention will be further described in detail below with reference to the accompanying drawings, without limiting the general inventive concept.

[0038] The diagram shows: Figure 1 The cross-sectional view of the motor is known in the prior art. Figure 2 A partial cross-sectional view of one rotor pole of a permanent magnet-excited rotor is known from existing technology. Figure 3 A partial cross-sectional view of one rotor pole in a first embodiment of a permanent magnet excited rotor. Figure 4 A partial cross-sectional view of one rotor pole in a second embodiment of a permanent magnet driven rotor. Figure 5 A partial cross-sectional view of a rotor pole with a vector potential line in a second embodiment of a permanent magnet excited rotor. Figure 6 A partial cross-sectional view of a rotor pole with a magnetic flux path in a second embodiment of a permanent magnet excited rotor. Figure 7 A partial cross-sectional view of the annular segmental opening. Figure 8 Cross-sectional view and partial view of the third embodiment of the permanent magnet excited rotor. Figure 9 Cross-sectional view and partial view of the fourth embodiment of the permanent magnet excited rotor. Figure 10 A schematic diagram of a motor vehicle with an electrically driven power transmission system. Detailed Implementation

[0039] Figure 1 A cross-sectional view of a prior art motor 2 is shown. The motor 2 is configured as a radial flux motor with an inner rotor 1. An energized stator winding 14 is embedded in stator slots 13 arranged circumferentially in the stator body 12.

[0040] The rotor 1 is configured as a permanent magnet driven rotor 1, including a rotor body 3. The rotor body 3 has a plurality of magnet receiving slots 4 for accommodating permanent magnets 5. The magnet receiving slots are configured to form rotor poles 6 that are circumferentially distributed along the rotor body 3 and alternately magnetized in opposite directions. Figure 1 The center is schematically represented by a circle and its north / south pole magnetization.

[0041] like Figure 2 As shown, adjacent magnet receiving slots 4 in the circumferential direction of a rotor pole 6 are separated from each other by a radially extending bridge portion 7.

[0042] Figure 1-2 A configuration of a permanent magnet driven rotor 1 known in the prior art is shown. An embodiment of the rotor 1 of the present invention is shown in... Figure 3 In this embodiment, the magnet receiving groove 4 of a rotor pole 6 is arranged along a first radially inner cross-sectional profile 9 and a second radially outer cross-sectional profile 10. The first cross-sectional profile 9 and the second cross-sectional profile 10 each extend along a convex function. Figure 3 It can also be seen that three magnet receiving slots 4a are arranged along the first cross-sectional profile 9, and three magnet receiving slots 4b are arranged along the second cross-sectional profile 10.

[0043] Between the magnet receiving grooves 4a of the first cross-sectional profile 9, an annular segmental opening 8a is formed in the rotor body 3, which is radially aligned with and radially spaced outward from the bridge portion 7a. Figure 4 One embodiment is shown in which, in addition to the magnet receiving grooves 4b of the second cross-sectional profile 10, an annular segmental opening 8b is also formed in the rotor body 3, which is radially aligned with and radially spaced outward from the bridge portion 7b.

[0044] Figure 4 It is also shown that the width of the bridge portion 7a between the magnet receiving grooves 4a of the first cross-sectional profile 9 is smaller than the width of the bridge portion 7b between the magnet receiving grooves 4b of the second cross-sectional profile 10.

[0045] from Figure 4 It can also be seen that an annular segmental opening 8a associated with the bridge portion 7a of the first cross-sectional profile 9 has a smaller arc angle 11 than an annular segmental opening 8b associated with the bridge portion 7b of the second cross-sectional profile 10. The arc angle 11 is also shown in... Figure 6 middle.

[0046] from Figure 3-4It can also be clearly seen that the annular segmental opening 8 extends substantially parallel to the cross-sectional profile 10. Therefore, the openings 8 point with their respective ends toward the outer peripheral surface of the rotor 1.

[0047] like Figure 5 Furthermore, an annular opening 8 extends around it along a vector potential line 15 that targets the pure q current and the unmagnetized permanent magnet 5. With this arrangement, leakage is significantly reduced because the opening 8 extends along the vector potential line 15, thus preventing narrowing of the magnetic flux path. This contributes to improved efficiency and performance of the motor 2. Figure 6 This illustrates how the relevant flux path extends to correspond to the torque generated by the permanent magnets in the rotor 1 of motor 2. This is achieved through... Figure 6 The slanted areas and arrows in the diagram illustrate this. It is clear that the arc length or radius 11 of the opening 8 arranged in the rotor body 3 is configured so that the magnetic flux path does not narrow significantly. This ensures optimal magnetic flux distribution and minimizes losses caused by magnetic field leakage. By precisely configuring the opening 8, the high-efficiency output of the motor 2 is guaranteed.

[0048] With the help of Figure 7 Further details regarding the geometric structure of the rotor body 3 can be provided. The magnet receiving groove 4 has a generally rectangular basic outline, wherein a flux guiding profile can be formed on the short side to deviate from the rectangular shape, for example, in... Figure 2-5 As seen in the implementation, the annular segmental opening 8 is centered relative to the radial axis 16 and spans an arc angle 11, with its center point located on the radial axis 16.

[0049] The bridge section 7 is also centered relative to the radial axis 16.

[0050] The arc angle 11 divides the cross-sectional area of ​​the permanent magnet 5 arranged in the magnet receiving groove 4 into a region 18 located within the corner of the arc angle 11 and a region 17 located outside the corner. Here, the sum of the regions 18 located within the corner of the arc angle 11 is greater than the sum of the regions 17 located outside the corner of the arc angle 11. In this context, it is particularly preferred that the sum of the regions 18 located within the corner of the arc angle 11 is at least twice the sum of the regions 17 located outside the corner of the arc angle 11.

[0051] Figure 8 and Figure 9 A further embodiment of the rotor 1 of the present invention is shown. Here, the rotor 1 has a magnet receiving groove 4 configuration different from the previous embodiment, which can also be called a V-shaped magnet receiving groove configuration, wherein the V-shaped magnet receiving groove is arranged to form one rotor pole 6 of the rotor 1. From Figure 8-9It can also be clearly seen that the annular segmental opening 8 can also be defined as a broken line composed of multiple straight lines. Furthermore, regarding the functions of the opening 8 and the bridge portion 7, please refer to the foregoing embodiments.

[0052] at last, Figure 10 The motor 2 is shown to be applicable to the powertrain system 20 of an electric vehicle 21.

[0053] This invention is not limited to the embodiments shown in the figures. Therefore, the above description should not be construed as restrictive, but rather as illustrative. The following patent claims should be understood as meaning that the described features are present in at least one embodiment of the invention. This does not exclude the presence of other features. If the patent claims and the above description define "first" and "second" features, this designation is used to distinguish between two similar features, without establishing a hierarchical order.

[0054] List of reference numerals 1. Rotor 2 motors 3 Rotor body 4 Magnet receiving slot 5 permanent magnets 6 rotor poles 7. Bridge section 8 Opening 9. Cross-sectional profile 10. Cross-sectional profile 11. Rounded corners 12 Stator body 13 stator slots 14 Stator windings 15 Vector Potential Lines 16 Radial axis 17 Area Segment 18 Sections 20 Powertrain System 21. Motor vehicles.

Claims

1. A permanent magnet driven rotor (1) for an electric motor (2), comprising: A rotor body (3) having a plurality of magnet receiving slots (4) for accommodating permanent magnets (5), the magnet receiving slots being configured to form rotor poles (6), the rotor poles being arranged circumferentially along the rotor body (3) and alternately magnetized in opposite directions, wherein every two magnet receiving slots in circumferentially adjacent magnet receiving slots (4) of a rotor pole (6) are separated from each other by a radially extending bridge portion (7), characterized in that an annular segmental opening (8) is formed in the rotor body (3) and is radially spaced outward from at least one magnet receiving slot (4).

2. The rotor (1) according to claim 1, characterized in that, Each pair of magnet receiving slots in the circumferentially adjacent magnet receiving slots (4) of a rotor pole (6) is separated from each other by a radially extending bridge portion (7), and an annular segmental opening (8) is formed in the rotor body (3) that is radially aligned with and radially spaced from at least one bridge portion (7).

3. The rotor (1) according to claim 2, characterized in that, The annular segmental opening (8) is formed at multiple bridge portions (7) between magnet receiving slots (4) of a rotor pole (6), preferably at all bridge portions (7).

4. The rotor (1) according to any one of the preceding claims, characterized in that, An annular opening (8) extends around it along a vector potential line that extends for a pure q current.

5. The rotor (1) according to any one of the preceding claims, characterized in that, A magnet receiving slot (4) of a rotor pole (6) is arranged along a first radial inner cross-sectional profile (9) and / or a second radial outer cross-sectional profile (10).

6. The rotor (1) according to any one of claims 2 to 5, characterized in that, Between the magnet receiving grooves (4a) of the first cross-sectional profile (9), an annular segment opening (8a) is formed in the rotor body (3) that is radially aligned with and radially spaced apart from the bridge portion (7a), and / or between the magnet receiving grooves (4b) of the second cross-sectional profile (10), an annular segment opening (8b) is formed in the rotor body (3) that is radially aligned with and radially spaced apart from the bridge portion (7b).

7. The rotor (1) according to claim 5 or 6, characterized in that, The width of the bridge (7a) between the magnet receiving grooves (4a) of the first cross-sectional profile (9) is smaller than the width of the bridge (7b) between the magnet receiving grooves (4b) of the second cross-sectional profile (10).

8. The rotor (1) according to any one of claims 5 to 7, characterized in that, An annular segmental opening (8a) associated with the bridge portion (7a) of the first cross-sectional profile (9) has a smaller arc angle (11) than an annular segmental opening (8b) associated with the bridge portion (7b) of the second cross-sectional profile (10).

9. The rotor (1) according to any one of claims 5 to 8, characterized in that, The first cross-sectional profile (9) and / or the second cross-sectional profile (10) extend along a convex function.

10. The rotor (1) according to any one of claims 5 to 9, characterized in that, At least three magnet receiving slots (4a) are arranged along the first cross-sectional profile (9) and / or at least three magnet receiving slots (4b) are arranged along the second cross-sectional profile (10).

11. An electric motor (2), particularly an electric motor for a power transmission system (20) of an electric vehicle (21), comprising a permanent magnet excitation rotor (1) according to claim 1.

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