Rotor of an electric high-speed machine

Abstract

Rotor of an electrical high-speed machine (2), in particular a permanent magnet synchronous machine, with a rotor body (4) rotatable about a rotor axis (3), which has rotor poles (5) each comprising a radially outer magnetic layer (6), at least two magnets (7), in particular permanent magnets, per radially outer magnetic layer (6), and each comprising a pole center axis (5d), wherein the magnets (7) are designed to be rare earth-free, wherein at least one magnetic pocket (10) is provided for each outer magnetic layer (6) for receiving the magnets (7), which pocket, viewed in the radial direction with respect to the rotor axis (3), each has an outer pocket side (10a) and an inner pocket side (10i), characterized in that the rotor (1) has at least twelve, in particular at least sixteen rotor poles (5).

Description

State of the art

[0001] The invention is based on a rotor of an electric high-speed machine according to the preamble of the main claim.

[0002] A rotor of an electric machine is already known from DE102014102411 A1, which comprises a rotor body with rotor poles that can rotate about a rotor axis. The rotor poles each comprise a radially outer magnetic layer, at least two magnets, in particular permanent magnets, per radially outer magnetic layer, and a pole center axis. Some of the magnets are rare-earth-free. At least one magnetic pocket is provided per outer magnetic layer to accommodate the magnets. The magnetic pockets each have an outer pocket side and an inner pocket side, viewed in the radial direction relative to the rotor axis. Advantages of the invention

[0003] The rotor according to the invention of an electric high-speed machine with the characterizing features of the main claim has the advantage that the demagnetization resistance of the rare-earth-free magnets arranged in the rotor is increased by the rotor having at least twelve, in particular at least sixteen rotor poles.

[0004] The measures listed in the subclaims enable advantageous further developments and improvements of the rotor of an electric high-speed machine specified in the main claim.

[0005] It is particularly advantageous if two lugs are formed on the outer sides of the pockets of the radially outer magnetic layers, each of which engages behind an outer magnetic corner of an outer magnet with respect to the pole center axis, said corner facing the respective pocket outer side and facing away from the respective pole center axis, in order to prevent demagnetization of the respective magnet. The demagnetization load of the magnets is not uniformly distributed across the individual magnets, since the individual magnets are not subjected to a homogeneous field. Without the lugs according to the invention, the highest demagnetization loads occur at the outer magnetic corners of the magnets. The lugs according to the invention can reduce the demagnetization load at the outer magnetic corners of the magnets, since the field in the individual magnets becomes more uniform.

[0006] It is further advantageous if the noses each have a nose flank that rests against a magnet side of the respective magnet facing away from the pole center axis, with the nose flanks each having a flank height that is in particular greater than 0.2 times the magnet thickness of the respective magnet. In this way, the demagnetization load at the outer corners of the magnets can be reduced.

[0007] It is very advantageous if the outer side of the respective magnetic pocket has a support surface intended for supporting one of the magnets. According to a second embodiment, a groove-shaped recess can be formed in the support surface at the transition to the nose flank of the respective nose. The strong demagnetization fields occurring at the outer corner of the magnets can be locally reduced in this way.

[0008] Rare-earth-free magnets, in particular, have a coercive field strength of less than 500 kA / m. Rare-earth-free magnets are made from materials such as iron nitride or iron nickel.

[0009] Furthermore, it is advantageous if the ratio of the magnet width to the pole pitch is in the range of 0.4*1 / k to 0.6*1 / k, where k corresponds to the number of magnets spanning the respective rotor pole in the circumferential direction. This can further increase the demagnetization resistance of the magnets arranged in the rotor.

[0010] Furthermore, it is advantageous if the ratio of the magnet thickness to the pole pitch is in the range of 0.25 to 0.4. This can further increase the demagnetization resistance of the magnets arranged in the rotor.

[0011] It is advantageous if the ratio of the magnet thickness to the magnet width is greater than 0.55*k, where k corresponds to the number of magnets spanning the respective rotor pole in the circumferential direction. This allows the demagnetization resistance of the magnets arranged in the rotor to be further increased.

[0012] According to an advantageous embodiment, the radially outer magnetic layers are V-shaped, C-shaped, curved, I-shaped or straight.

[0013] According to an advantageous further embodiment, the radially outer magnetic layers can be arranged symmetrically to the respective pole center axis.

[0014] The invention further relates to an electric high-speed machine with a rotor according to the invention. drawing

[0015] Two embodiments of the invention are shown in simplified form in the drawing and explained in more detail in the following description.

[0016] They show: Fig. 1 an electric high-speed machine with a rotor according to the invention, Fig. 2 a partial view of the machine according to Fig. 1 with a rotor according to a first embodiment and Fig. 3 a partial view of the machine according to Fig. 1 with a rotor according to a second embodiment. Description of the embodiments

[0017] Fig. 1 shows an electric high-speed machine with a rotor according to the invention.

[0018] A high-speed machine is an electrical machine designed for maximum speeds greater than 12,000 rpm.

[0019] The rotor 1 according to the invention of the high-speed electric machine 2, in particular a permanent magnet synchronous machine, has a rotor body 4 rotatable about a rotor axis 3, which has rotor poles 5, each comprising a radially outer magnetic layer 6 with respect to the rotor axis 3, at least two magnets 7, in particular permanent magnets, per radially outer magnetic layer 6, and each comprising a pole center axis 5d (d-axis). The radially outer magnetic layers 6 can be V-shaped, C-shaped, arcuate, I-shaped, or rectilinear, for example, and arranged, for example, symmetrically to the respective pole center axis 5d.

[0020] The rotor 1 has a pole pitch which results from the circumference of the rotor divided by the number of poles of the rotor.

[0021] A stator 8 is assigned to the rotor 1. For example, the rotor 1 is enclosed by the stator 8. An annular air gap 9 is provided between the rotor 1 and the stator 8. The machine 2 is intended for driving vehicles, i.e., as a traction machine.

[0022] The magnets 7 of the radially outer magnetic layer 6 are rare earth-free, i.e., free of rare earths, and have a coercive field strength that is in particular less than 500 kA / m. The rare earth-free magnets 7 are made, for example, from iron nitride or iron nickel. The magnets 7 have a magnet thickness d and a magnet width b, with the magnet thickness d and the magnet width b being measured according to the dimension lines in the figures.

[0023] For each outer magnetic layer 6, at least one magnetic pocket 10 is provided for receiving the magnets 7, which pocket has an outer pocket side 10a and an inner pocket side 10i as seen in the radial direction with respect to the rotor axis 3.

[0024] On the one hand, the magnets 7 of the rotor 1 should be arranged as close as possible to the air gap 9 in order to achieve high electrical performance of the machine 2. On the other hand, the magnets 7 or sections of the magnets 7 located close to the air gap 9 are easier to demagnetize in the event of a short circuit.

[0025] In order to increase the demagnetization resistance of the magnets 7, the invention provides that the rotor 1 has at least twelve, in particular at least sixteen rotor poles 5.

[0026] Fig. 2 shows a partial view of the machine after Fig. 1 with a rotor according to a first embodiment.

[0027] On the pocket outer sides 10a of the radially outer magnetic layers 6, two lugs 11 are formed for each rotor pole 5, each of which engages behind an outer magnet corner 7c of an outer magnet 7 with respect to the pole center axis 5d, said outer magnet corner facing the respective pocket outer side 10a and facing away from the respective pole center axis 5d, in order to prevent demagnetization of the respective magnet 7.

[0028] The noses 11 each rest with a nose flank 11f on a magnet side 7a of the respective magnet 7 facing away from the pole center axis 5d. The nose flanks 11f each have a flank height 11h that is in particular greater than 0.2 times the magnet thickness d of the respective magnet 7.

[0029] The ratio of a magnet width b of the magnets 7 to the pole pitch is in the range from 0.4*1 / k to 0.6*1 / k, where k corresponds to the number of magnets 7 that span the respective rotor pole 5 in the circumferential direction.

[0030] The ratio of a magnet thickness d of the magnets 7 to the pole pitch is in the range of 0.25 to 0.4.

[0031] The ratio of the magnet thickness d to the magnet width b of the magnets 7 is greater than 0.55*k, where k corresponds to the number of magnets 7 that span the respective rotor pole 5 in the circumferential direction.

[0032] Fig. 3 shows a partial view of the machine after Fig. 1 with a rotor according to a second embodiment.

[0033] According to the second embodiment, the pocket outer side 10a of the respective magnetic pocket 10 can have a support surface 12 which is provided for supporting one of the magnets 7 and in which a groove-shaped depression 12n is formed at the transition to the nose flank 11f of the respective nose 11. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 102014102411 A1

[0002]

Claims

[1] Rotor of an electrical high-speed machine (2), in particular a permanent magnet synchronous machine, with a rotor body (4) rotatable about a rotor axis (3), which has rotor poles (5) each comprising a radially outer magnetic layer (6), at least two magnets (7), in particular permanent magnets, per radially outer magnetic layer (6), and each comprising a pole center axis (5d), wherein the magnets (7) are designed to be rare earth-free, wherein at least one magnetic pocket (10) is provided for each outer magnetic layer (6) for receiving the magnets (7), which pocket has an outer pocket side (10a) and an inner pocket side (10i) as seen in the radial direction with respect to the rotor axis (3), characterized by that the rotor (1) has at least twelve, in particular at least sixteen rotor poles (5). [2] Rotor according to claim 1, characterized byin that two lugs (11) are formed on the pocket outer sides (10a) of the radially outer magnetic layers (6), each of which engages behind an outer magnet corner (7c) of an outer magnet (7) with respect to the pole center axis (5d), said outer magnet corner facing the respective pocket outer side (10a) and facing away from the respective pole center axis (5d), in order to avoid demagnetization of the respective magnet (7). [3] Rotor according to claim 2, characterized by that the noses (11) each rest with a nose flank (11f) on a magnet side (7a) of the respective magnet (7) facing away from the pole center axis (5d), wherein the nose flanks (11f) each have a flank height (11h) which is in particular greater than 0.2 times a magnet thickness (d) of the respective magnet (7). [4] Rotor according to claim 3, characterized bythat the pocket outer side (10a) of the respective magnetic pocket (10) has a support surface (12) which is provided for supporting one of the magnets (7) and in which a groove-shaped depression (12n) is formed at the transition to the nose flank (11f) of the respective nose (11). [5] Rotor according to one of the preceding claims, characterized by that the rare earth-free magnets (7) have a coercive field strength of less than 500kA / m. [6] Rotor according to one of the preceding claims, characterized by that the magnets (7) are made on the basis of iron nitride or iron nickel. [7] Rotor according to one of the preceding claims, characterized by that the ratio of a magnet width (b) of the magnets (7) to the pole pitch is in the range from 0.4*1 / k to 0.6*1 / k, where k corresponds to the number of magnets (7) spanning the respective rotor pole (5) in the circumferential direction. [8] Rotor according to one of the preceding claims, characterized bythat the ratio of a magnet thickness (d) of the magnets (7) to the pole pitch is in the range of 0.25 to 0.

4. [9] Rotor according to one of the preceding claims, characterized by that the ratio of a magnet thickness (d) to a magnet width (b) of the magnets (7) is greater than 0.55*k, where k corresponds to the number of magnets (7) spanning the respective rotor pole (5) in the circumferential direction. [10] Rotor according to one of the preceding claims, characterized by that the radially outer magnetic layers (6) are V-shaped, C-shaped, curved, I-shaped or straight. [11] Rotor according to one of the preceding claims, characterized by that the radially outer magnetic layers (6) are arranged symmetrically to the respective pole center axis (5d). [12] High-speed electric machine with a rotor (1) according to one of the preceding claims.

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