ROTOR OF AN ELECTRICAL MACHINE WITH MULTI-LAYER PERMANENT MAGNET ARRANGEMENT

Description

State of the art

[0001] The present invention relates to a rotor of an electrical machine.

[0002] The invention also relates to an electrical machine comprising such a rotor. The rotor has a multilayer arrangement of permanent magnets.

[0003] Electrical machines are known from the prior art. These often have a rotor in which permanent magnets are provided. These permanent magnets can be arranged in various configurations within the rotor. For example, a multilayer arrangement of permanent magnets in the form of a multi-C arrangement with four layers is known from FR 2 973 179 B1. Another similar arrangement is known from US 2013 / 307363 A1.

[0004] GB2551537A is considered to be the closest prior art and discloses the features of the preamble of independent main claim 1.

[0005] The object of the invention is to provide a rotor of an electrical machine which ensures high torque and high power for the electrical machine while maintaining high speed stability and low torque ripple.

[0006] The object of the invention is achieved by a rotor of an electrical machine according to the features of the independent main claim 1.

[0007] The subclaims show preferred developments of the invention. Disclosure of the invention

[0008] The rotor according to the invention, with the characterizing features of independent main claim 1, has a multilayer arrangement of permanent magnets, which enables an increase in the magnetic rotor flux compared to the prior art. At the same time, the rotor's speed stability is increased. Furthermore, the rotor enables the reduction of magnetic losses due to harmonics, thereby increasing the overall continuous performance of an electrical machine.

[0009] The multilayer arrangement of permanent magnets is not only achieved by using many small permanent magnets, but also allows the use of larger permanent magnets compared to the state of the art. This results in greater demagnetization resistance, allowing higher rotor temperatures to be tolerated without negatively impacting the performance of the electric machine.

[0010] The rotor has a rotor body rotatable about a rotor axis. The rotor body is formed, in particular, by a plurality of individual laminations stacked to form a lamination stack. The individual laminations are made, in particular, of electrical steel sheet, particularly preferably punched. The rotor body has an outer circumference and a plurality of rotor poles, each rotor pole having a pole center axis and an arrangement of permanent magnets arranged in inner pockets of the rotor body. The pockets are thus preferably formed in the stack of individual laminations.

[0011] The arrangement of permanent magnets comprises two layers of permanent magnets spaced apart in the radial direction, with the radially inner layer having two inner pockets arranged symmetrically to the pole center axis and an inner web provided between the two inner pockets. The radially outer layer has an outer pocket arranged symmetrically to the pole center axis. The radially outer layer thus particularly advantageously has such a pocket that is tangential to the pole center axis. Such an arrangement can significantly reduce, in particular, critical orders of torque ripple.

[0012] According to the invention, the inner web is a single web arranged symmetrically to the pole center axis. The inner web thus advantageously extends along the pole center axis and thus separates the two inner pockets from one another. Two additional pockets acting as flux barriers are provided between the outer circumference of the rotor body and the outer pocket. The additional pockets are also arranged symmetrically to the pole center axis. Each additional pocket forms a first outer web between the additional pocket and the outer pocket. Thus, two first outer webs are present, between which the outer pocket is located. Such an arrangement of pockets and webs is also referred to below as a C-minus arrangement. This follows in particular from the fact that the permanent magnets of the radially inner layer are arranged in a C-shape, while the radially outer layer has, in particular, the shape of a minus.

[0013] The rotor described is particularly suitable for use in electrical machines for hybrid vehicles or electric vehicles and is particularly suitable for use in permanent-magnet synchronous machines. If the rotor is used in such electrical machines, high torques and high power outputs can be achieved while simultaneously maintaining high speed stability. The arrangement also enables the permanent magnets used to have high demagnetization resistance, which increases the rotor limit temperature. This leads in particular to the aforementioned high continuous performance of the electrical machine. Furthermore, the arrangement of the permanent magnets, particularly the arrangement in the radially outer layer, enables low torque ripple. Further advantages of the aforementioned arrangement are low losses, in particular low iron losses and magnet losses, as well as low material and manufacturing costs.

[0014] Particularly preferably, each additional pocket additionally forms a second outer web between the outer circumference of the rotor body and the additional pocket. Thus, the additional pocket is bounded by the first outer web and the second outer web and thus has a closed cross-section, at least in the plane perpendicular to the axis of rotation. The additional pocket advantageously remains empty and is thus filled only with ambient air. In this way, the additional pocket acts as a flux barrier, while the second outer webs ensure high torque resistance of the rotor.

[0015] In an alternative embodiment (not shown), it is preferably provided that the additional pockets in the stack of laminations are open toward the outer circumference. Thus, the previously described second outer webs are not present. In this case, the additional pockets are advantageously filled with a magnetically non-conductive mass. The magnetically non-conductive mass, in particular, increases the mechanical stability of the rotor, whereby the corresponding additional pocket acts as a flux barrier on the one hand, and ensures the speed stability of the rotor on the other.

[0016] Advantageously, a plurality of permanent magnets are arranged one behind the other in the axial direction in each inner pocket and / or outer pocket. Thus, the axial dimension of each permanent magnet is not necessarily identical to the axial dimension of the rotor body. Rather, several permanent magnets can be arranged one behind the other in the axial direction to fill the inner pockets and / or outer pockets.

[0017] According to the invention, two permanent magnets of the radially inner layer are arranged symmetrically with respect to the pole center axis and each enclose an acute opening angle α i1 , α i2 with respect to one another. This means that the permanent magnets form an angle with respect to one another that is less than 180°. The two first outer webs of the radially outer layer enclose an acute web angle β sa with respect to one another. According to the invention, it is further provided that the opening angle α i1 , α i2 of each pair of symmetrically arranged permanent magnets of the radially inner layer is greater than the web angle β sa between the first outer webs. This leads in particular to an optimized magnetic flux within the rotor, whereby high performance of the electrical machine using the rotor can be achieved with simultaneous high torque strength.

[0018] Advantageously, it is also provided that the inner web of each rotor pole has a width b si measured in the circumferential direction of the rotor. The first outer webs of each rotor pole have a width b sa measured in the circumferential direction of the rotor. Advantageously, the width b si of the inner web is larger than the width b sa of the first outer webs. This allows for an optimal design of the respective webs depending on the forces to be supported and optimized for a maximum magnetic rotor flux point; in particular, stray fluxes can be minimized.

[0019] Preferably, a single permanent magnet is arranged between the first outer webs of each outer pocket. This applies particularly within the plane perpendicular to the rotation axis, so that it is still possible to stack multiple permanent magnets in the axial direction.

[0020] In each of the two inner pockets, at least two adjacent permanent magnets are preferably arranged between the inner web and the outer circumference of the rotor body. This again preferably applies in the plane perpendicular to the axis of rotation, thus further enabling the axial stacking of multiple permanent magnets. The two permanent magnets per inner pocket are arranged in particular such that they at least partially encompass the permanent magnet in the outer pocket. This, in particular, allows the previously described C-minus arrangement to be achieved in a simple manner.

[0021] The two inner pockets are preferably bent in such a way that the permanent magnets of each inner pocket are at different angles to the pole center axis. This, in particular, realizes the previously described C-shape. The arrangement of the permanent magnets and the assembly of the rotor are thus simplified.

[0022] Preferably, the magnets of each rotor pole, in particular the magnets of the entire rotor, have identical dimensions. This makes the provision of the permanent magnets simple and inexpensive. Furthermore, rotor assembly is simplified because an identical permanent magnet can be used in every position intended for magnet assembly.

[0023] The invention further relates to an electrical machine according to claim 9. The electrical machine has a rotor as described above. Furthermore, the electrical machine has a stator for driving the rotor. The use of the rotor as described above leads, in particular, to the aforementioned advantageous properties of the electrical machine. Short description of the drawing

[0024] Embodiments of the invention are described in detail below with reference to the accompanying drawings. In the drawing: Figure 1 schematic illustration of an electrical machine according to an embodiment of the invention

[0025] Figure 1 schematically shows an electric machine 10 according to an embodiment of the invention. The electric machine 10 has a stator 11 and a rotor 1. The stator 11 serves to drive the rotor 1. The illustration in Figure 1 is only for a single rotor pole 5 of the rotor 1, with the remaining arrangement of the rotor 1 and / or stator 11 preferably being symmetrical to the section shown.

[0026] The rotor 1 has a rotor body 2, which is designed to be rotatable about a rotation axis 100. The rotor body 2 is preferably formed from a plurality of stacked laminations. The laminations are, for example, stamped from electrical steel sheet.

[0027] The rotor body 2 has an outer circumference 8 and a plurality of magnetic pockets 6, 7. The rotor body 2 also forms a plurality of rotor poles 5, wherein, as previously described, only one of these rotor poles 5 is shown in Figure 1. Said rotor pole 5, in turn, has a pole center axis 101, wherein the rotor pole 5 is formed symmetrically to this pole center axis 101.

[0028] Each rotor pole 5 has a multi-layer arrangement of permanent magnets 4, with permanent magnets 4 of a radially inner layer 3i and permanent magnets 4 of a radially outer layer 3a being provided. The radially inner layer 3i is arranged at a radial distance from the radially outer layer 3a. The radially inner layer 3i has two inner pockets 6 arranged symmetrically to the pole center axis 101. An inner web 9i is provided between the two inner pockets 6. The inner web 9i is a single web arranged symmetrically to the pole center axis 101.

[0029] The radially outer layer 3a has an outer pocket 7 arranged symmetrically to the pole center axis 101. Furthermore, two additional pockets 12 acting as a flux barrier and arranged symmetrically to the pole center axis 101 are provided between the outer circumference 8 of the rotor body 2 and the outer pocket 7. A first outer web 9a is arranged between each additional pocket 12 and the outer pocket 7. A second outer web 9u is also provided between each additional pocket 12 and the outer circumference 8 of the rotor body 2. Thus, a cross-section of the additional pockets 12 is closed at least with respect to the plane perpendicular to the rotation axis 100. However, alternative embodiments (not shown) are also possible, such as, in particular, the design of the additional pockets 12 with an open cross-section, in which the additional pockets 12 are open towards the outer circumference 8.In this case, the additional pockets 12 are advantageously filled with a magnetically non-conductive material to increase mechanical strength. A corresponding filling other than air is not necessary in the embodiment shown in Figure 1; rather, the additional pocket 12 is left free and thus filled only with ambient air. In this case, the effect as a flow barrier is achieved simply and with little effort.

[0030] In the outer pocket 7, only one permanent magnet 4 is mounted between the two first outer webs 9a. This applies in particular to the plane perpendicular to the rotation axis 100, since several permanent magnets 4 can advantageously be stacked in the axial direction relative to the rotation axis 100.

[0031] In each inner pocket 6, preferably two permanent magnets 4 are arranged between the inner web 9i and the outer circumference 8 of the rotor body 2. This also applies in particular to the plane perpendicular to the rotation axis, since here, too, several permanent magnets 4 can be stacked in the axial direction relative to the rotation axis 100.

[0032] Each inner pocket 6 is preferably angled, so that each permanent magnet 4 of the inner pocket 6 has a different angle to the pole center axis 101. The symmetrical design of the two inner pockets 6 of a rotor pole 5 with respect to the pole center axis 101 thus ensures that two permanent magnets 4 of each inner pocket 6 are arranged symmetrically to one another. Each of these pairs of symmetrically arranged permanent magnets 4 forms an acute opening angle α i1 and α i2 . In Figure 1, the symmetrically arranged permanent magnets 4 located radially further inside form the acute opening angle α i2 while the two permanent magnets 4 of the inner pockets 6 located radially further out form the acute opening angle α i1. The two first outer webs 9a of the radially outer layer 3a also form an acute angle, the acute web angle β sa .

[0033] It is intended that each opening angle α i1 and α i2 is larger than the web angle β sa . In this way, the magnetic fluxes within the rotor 1 can be optimized to maximize the performance of the electric machine 10.

[0034] Furthermore, it is provided that the inner web 9i has a width b si measured in the circumferential direction of the rotor 1. The first outer webs 9a have a width b sa measured in the circumferential direction of the rotor 1. Here, it is provided that the width b si of the inner web 9i is larger than the width b sa of the first outer web 9a. Thus, the sizes of the corresponding webs 9i, 9a are optimized with regard to existing force conditions, while the formation of stray fluxes is minimized.

[0035] The previously described design of the radially inner layer 3i and the radially outer layer 3a enables the permanent magnets 4 to be provided in a C-minus arrangement, whereby this arrangement is simple and inexpensive to achieve. In particular, it is provided that all permanent magnets 4 provided in the rotor pole 5 have identical dimensions. This simplifies the assembly of the rotor 1, since no assignment of permanent magnets 4 to specific positions needs to be taken into account. At the same time, the C-minus arrangement enables an optimized rotor flux with increased torque resistance. This, on the one hand, enables high torque and high power. On the other hand, due to the possibility of using larger permanent magnets 4, the demagnetization resistance of the permanent magnets 4 and thus the rotor limit temperature are increased. This increases the continuous performance of the electric machine 10.The simple arrangement described above also allows manufacturing and material costs to be minimized.

Claims

1. Rotor (1) of an electric machine (10), comprising a rotor body (2) which can be rotated about a rotor axis (100), has an outer circumference (8) and a plurality of rotor poles (5) and is formed by a stack of laminations, wherein each rotor pole (5) has a pole central axis (101) and an arrangement of permanent magnets (4) arranged in pockets (6, 7) of the rotor body (2), in particular the stack of laminations, wherein the arrangement of permanent magnets (4) comprises two layers (3i, 3a) spaced apart from each other in the radial direction and having permanent magnets (4), wherein the radially inner layer (3i) has two inner pockets (6) arranged symmetrically with respect to the pole central axis (101) and an inner connecting portion (9i) situated between the two inner pockets (6), wherein the radially outer layer (3a) has an outer pocket (7) arranged symmetrically with respect to the pole central axis (101), wherein the inner connecting portion (9i) is a single connecting portion arranged symmetrically with respect to the pole central axis (101), wherein two additional pockets (12) acting as a flux barrier and arranged symmetrically with respect to the pole central axis (101) are provided between the outer circumference (8) of the rotor body (2) and the outer pocket (7), wherein each additional pocket (12) forms a first outer connecting portion (9a) between the additional pocket (12) and the outer pocket (7), wherein in each case two permanent magnets (4) of the radially inner layer (3i) are arranged symmetrically with respect to the pole central axis (101) and each include an acute opening angle αi1, αi2, wherein the two first outer connecting portions (9a) of the radially outer layer (3a) include an acute connecting portion angle βsa , characterized in that at least two permanent magnets (4) situated next to each other are arranged in each of the two inner pockets (6) in each case between the inner connecting portion (9i) and the outer circumference (8) of the rotor body (2), in that the opening angle αi1, αi2 of each pair of symmetrically arranged permanent magnets (4) of the radial inner layer (3i) is greater than the connecting portion angle βsa between the first outer connecting portions (9a), and in that the acute connecting portion angle βsa is open to the outer circumference (8) of the rotor body (2).

2. Rotor according to Claim 1, characterized in that each additional pocket (12) additionally forms a second outer connecting portion (9u) between the outer circumference (8) of the rotor body (2) and the additional pocket (12).

3. Rotor according to Claim 1, characterized in that the additional pockets (12) in the stack of laminations are designed to be open to the outer circumference (8) and filled with a magnetically non-permeable compound.

4. Rotor according to any of the preceding claims, characterized in that a plurality of permanent magnets (4) are arranged one behind the other in the axial direction with respect to the rotor axis in each inner pocket (6) and / or outer pocket (7).

5. Rotor (1) according to any of the preceding claims, characterized in that that the inner connecting portion (9i) of each rotor pole (5) has a width bsi measured in the circumferential direction of the rotor (1) and the first outer connecting portions (9a) of each rotor pole (5) have a width bsa measured in the circumferential direction of the rotor (1), wherein the width bsi of the inner connecting portion (9i) is greater than the width bsa of the first outer connecting portions (9a).

6. Rotor (1) according to any of the preceding claims, characterized in that a single permanent magnet (4) is arranged between the first outer connecting portions (9a) of each outer pocket (7).

7. Rotor (1) according to any of the preceding claims, characterized in that the two inner pockets (6) are each designed bent in such a way that the permanent magnets (4) of each inner pocket (6) are at different angles in relation to the pole central axis (101).

8. Rotor (1) according to any of the preceding claims, characterized in that the permanent magnets (4) of each rotor pole (5) have identical dimensions.

9. Electric machine (10) comprising a rotor (1) according to any of the preceding claims and a stator (11) for driving the rotor (1).