ROTOR FOR AN ELECTRIC MACHINE, ELECTRIC MACHINE, AND METHOD FOR OPERATING AN ELECTRIC MACHINE

Abstract

A rotor for an electric machine, wherein the electric machine includes a stator and the rotor, which is rotatable relative to the stator. The rotor includes a plurality of permanent magnets and a first rotor portion, which is formed from a first material having a first magnetic permeability. The first rotor portion includes at least one sub-portion of the rotor facing the stator in an operationally ready state of the electric machine. The permanent magnets are arranged at least in part in the first rotor portion. The rotor also includes a second rotor portion, which is formed from a second material having a second magnetic permeability which is lower than the first magnetic permeability. The second rotor portion includes a sub-portion of the rotor facing away from the stator in the operationally ready state of the electric machine.

Claims

1. A rotor for an electric machine, having a stator and the rotor, which is rotatable relative to the stator, comprising: a plurality of permanent magnets; a first rotor portion, which is formed from a first material having a first magnetic permeability, wherein the first rotor portion includes at least one sub-portion of the rotor facing the stator in an operationally ready state of the electric machine, wherein the permanent magnets are arranged at least in part in the first rotor portion; and a second rotor portion, which is formed from a second material having a second magnetic permeability which is lower than the first magnetic permeability, wherein the second rotor portion includes a sub-portion of the rotor facing away from the stator in the operationally ready state of the electric machine.

2. The rotor of claim 1, wherein the second rotor portion is formed from a diamagnetic and/or paramagnetic material.

3. The rotor of claim 1, wherein the first rotor portion is formed from steel and/or iron.

4. The rotor of claim 1, wherein the first rotor portion extends between the permanent magnets.

5. The rotor of claim 1, wherein the permanent magnets are arranged in a spoke configuration, and wherein axes of longitudinal extent of the permanent magnets are oriented radially in relation to the rotor.

6. The rotor of claim 1, wherein the rotor is configured to be surrounded rotatably, at least in part, by the stator, wherein the first rotor portion includes a radially outer sub-portion of the rotor, and wherein the second rotor portion includes a radially inner sub-portion of the rotor.

7. An electric machine, comprising: a stator; and a rotor, which is rotatable relative to the stator; wherein the rotor includes: a plurality of permanent magnets; a first rotor portion, which is formed from a first material having a first magnetic permeability, wherein the first rotor portion includes at least one sub-portion of the rotor facing the stator in an operationally ready state of the electric machine, wherein the permanent magnets are arranged at least in part in the first rotor portion; and a second rotor portion, which is formed from a second material having a second magnetic permeability which is lower than the first magnetic permeability, wherein the second rotor portion includes a sub-portion of the rotor facing away from the stator in the operationally ready state of the electric machine.

8. A method for operating an electric machine, the method comprising: supplying an electric current into at least one electric coil of a stator to bring about a rotary motion of a rotor relative to the stator; wherein the electric machine includes: the stator; and the rotor, which is rotatable relative to the stator; wherein the rotor includes: a plurality of permanent magnets; a first rotor portion, which is formed from a first material having a first magnetic permeability, wherein the first rotor portion includes at least one sub-portion of the rotor facing the stator in an operationally ready state of the electric machine, wherein the permanent magnets are arranged at least in part in the first rotor portion; and a second rotor portion, which is formed from a second material having a second magnetic permeability which is lower than the first magnetic permeability, wherein the second rotor portion includes a sub-portion of the rotor facing away from the stator in the operationally ready state of the electric machine.

9. The rotor of claim 1, wherein the second rotor portion is formed from a diamagnetic and/or paramagnetic material, which includes aluminum.

Description

BRIEF DESCRIPTIONS OF THE DRAWINGS

[0026] FIG. 1 shows a schematic depiction of a magnetic field of an electric machine on the basis of a sectional depiction of the electric machine.

[0027] FIG. 2 shows a schematic depiction of an exemplary embodiment of an electric machine.

[0028] FIG. 3 shows a schematic depiction of a magnetic field of an exemplary embodiment of an electric machine on the basis of a sectional depiction of the electric machine.

[0029] FIG. 4 shows a schematic torque-angular position chart for an exemplary embodiment of an electric machine.

[0030] FIG. 5 shows a flow diagram of an exemplary embodiment of a method for operating an electric machine.

DETAILED DESCRIPTION

[0031] FIG. 1 shows a schematic depiction of a magnetic field of an electric machine 100 on the basis of a sectional depiction of the electric machine 100. The electric machine 100 comprises a stator 110 and a rotor 120. Only a sub-portion of the electric machine 100 is shown in the depiction of FIG. 1.

[0032] FIG. 2 shows a schematic depiction of an exemplary embodiment of an electric machine 200. Here, the electric machine 200 is shown in particular in a schematic cross-sectional depiction. The electric machine 200 comprises a stator 210 and a rotor 220. The rotor 220 is rotatable, more specifically arranged or mounted rotatably, relative to the stator. The rotor 220 comprises a plurality of permanent magnets 222, a first rotor portion 224 and a second rotor portion 226. Furthermore, a rotor shaft 228 of the rotor 220 is shown. There is a gap or air gap located between the stator 210 and the rotor 220.

[0033] The rotor 220 is divided into the first rotor portion 224 and the second rotor portion 226. The first rotor portion 224 is formed from a first material having a first magnetic permeability. Here, the first rotor portion 224 comprises at least one sub-portion of the rotor 220 facing the stator 210. The permanent magnets 222 are arranged or embedded at least in part in the first rotor portion 224. The second rotor portion 226 is formed from a second material having a second magnetic permeability which is lower than the first magnetic permeability of the first material of the first rotor portion 224. Here, the second rotor portion 226 comprises a sub-portion of the rotor 220 facing away from the stator 210.

[0034] According to the exemplary embodiment shown in FIG. 2, the electric machine 200 is embodied as an internal-rotor electric motor. Here, the rotor 220 is configured to be surrounded rotatably, at least in part, by the stator 210. The first rotor portion 224 comprises a radially outer sub-portion of the rotor 220, wherein the second rotor portion 226 comprises a radially inner sub-portion of the rotor 220. Furthermore, in accordance with the exemplary embodiment shown in FIG. 2, the permanent magnets 222 are arranged in a spoke configuration. Here, axes of longitudinal extent of the permanent magnets 222 are oriented radially in relation to the rotor 220. In particular, the first rotor portion 224 extends between the permanent magnets 222. The second rotor portion 226 is formed for example from a diamagnetic and/or paramagnetic material, in particular aluminum. The first rotor portion 224 is formed in particular from steel and/or from iron.

[0035] In other words, FIG. 2 thus shows a schematic cross-section of an electric machine comprising a rotor 220 having permanent magnets 222 in a spoke orientation. The first rotor portion 224 for example comprises iron laminations and the second rotor portion 226 comprises aluminum, for example, as diamagnetic and/or paramagnetic material of lower magnetic permeability.

[0036] FIG. 3 shows a schematic depiction of a magnetic field of an exemplary embodiment of an electric machine 200 on the basis of a sectional depiction of the electric machine 200. Here, a sub-portion of the electric machine 200 is shown in the depiction of FIG. 3. The electric machine corresponds to or assimilates here the electric machine from one of the previously described figures, more specifically one of FIGS. 2 to 3. In the depiction of FIG. 3, only the stator 210 and the rotor 220 of the electric machine 200 are explicitly denoted.

[0037] In other words, FIG. 3 shows a magnetic field of a configuration of an electric machine 200 or of an electric motor according to an exemplary embodiment. Here too, the electric motor is embodied as an internal rotor. The radially inner part of the rotor 220 is constructed for example using aluminum. In particular, compared with FIG. 1, it can be seen that a reduced or minimized number of magnetic field lines enter the radially inner regions and an increased or maximized amount of magnetic flux passes into the air gap and into the stator 210.

[0038] FIG. 4 shows a schematic torque-angular position chart 400 for an exemplary embodiment of an electric machine. The electric machine corresponds to or assimilates here the electric machine from one of the previously described figures, more specifically one of FIGS. 2 to 3. An angular position or a rotary angle φ of the rotor of the electric machine in degrees [°] is plotted on the x-axis, and a torque M of the electric machine in Newton-meters [Nm] is plotted on the y-axis. The torque M is, for example, the mean output torque of an electric machine embodied as an electric motor. In the chart 400, a first graph 401 is shown as a comparison graph for a conventional electric machine and a second graph 402 is shown for the exemplary embodiment of the electric machine.

[0039] More specifically, FIG. 4 shows a comparison of torques M of a conventional electric machine, for example such as that from FIG. 1, and of an electric machine according to an exemplary embodiment, for example such as that from FIG. 2 and/or FIG. 3. It can be seen that the torque M or mean output torque of the exemplary embodiment of the electric machine is higher than a torque generated by a conventional electric machine. Thus, the first graph 401 is located between the second graph 402 and the x-axis. The mean output torque of the exemplary embodiment of the electric machine may be, for example, approximately 7.5% higher than a torque generated by a conventional electric machine.

[0040] FIG. 5 shows a flow diagram of an exemplary embodiment of a method 500 for operating an electric machine. The electric machine corresponds to or assimilates here the electric machine from one of the previously described figures, more specifically one of FIGS. 2 to 3. The electric machine thus comprises a stator and a rotor, wherein the rotor is rotatable relative to the stator. The rotor is constructed here in accordance with an exemplary embodiment described herein. The operating method 500 comprises a step 510 of supplying an electric current into at least one electric coil of the stator in order to bring about a rotary motion of the rotor relative to the stator. The electric machine is operable here by electric motor control methods in the art.

THE LIST OF REFERENCE SIGNS IS AS FOLLOWS

[0041] 100 electric machine [0042] 110 stator [0043] 120 rotor [0044] 200 electric machine [0045] 210 stator [0046] 220 rotor [0047] 222 permanent magnet [0048] 224 first rotor portion [0049] 226 second rotor portion [0050] 228 rotor shaft [0051] 400 torque-angular position chart [0052] 401 first graph [0053] 402 second graph [0054] M torque [0055] φ angular position or rotary angle [0056] 500 method for operating an electric machine [0057] 510 supply step