Method for Operating an Electric Motor

Abstract

The invention relates to a method for operating an electric motor (I), the electric motor (I) comprising at least one first stator (2) with at least three coils (3, 4, 5) and a rotor (6) with at least two magnets (7, 8), the first stator (2) and the rotor (6) being adjacently arranged in an axial direction (9), and the coils (3, 4, 5) being adjacently arranged in a peripheral direction (IO). The electric motor (I) is operated at least in the following two states: a) in a first state, the coils (3, 4, 5) are operated by respectively different phases of a three-phase current, and the rotor (6) is rotated about an axis of rotation (11); and b) in a second state, the coils (3, 4, 5) are operated by an equal-phase alternating current.

Claims

1. A method for operating an electric motor, wherein the electric motor has at least one first stator with at least three coils and a rotor with at least two magnets; wherein the first stator and the rotor are arranged one next to the other along an axial direction, wherein the coils are arranged one next to the other along a circumferential direction, wherein the electric motor is operated at least in the following two states: a) in a first state, the coils are operated with respective different phases of a three-phase current and the rotor is made to rotate about a rotational axis; b) in a second state, the coils are operated with an alternating current with the same phase.

2. The method as claimed in claim 1, wherein the electric motor is operated in both states, so that the rotor is driven by the operation of the electric motor in the first state and chronologically in parallel a body is heated by the operation of the electric motor in the second state.

3. The method as claimed in claim 1, wherein the electric motor has a second stator with at least three coils; wherein the rotor is arranged along the axial direction between the first stator and the second stator.

4. The method as claimed in claim 1, wherein an electrically conductive body, which is heated by induction at least during operation of the electric motor in the second state, is arranged in a radial direction at least within or outside at least one stator.

5. The method as claimed in claim 4, wherein a specific electrical first resistance of the body is lower than a specific electrical second resistance of a core of a coil.

6. The method as claimed in claim 4, wherein each coil has a core which extends starting from a first end to a second end of the at least one stator, wherein the rotor is arranged adjacent to the at least one second end; wherein the body extends along a circumferential direction completely and along an axial direction up to the at least one first end.

7. The method as claimed in claim 6, wherein the body is in contact, at the at least one first end, with the cores of the coils.

8. The method as claimed in claim 1, wherein in the second state a first portion of electrical power, which is applied to the electric motor, in the at least one stator and a second portion in the body are converted into heat, wherein the first portion is at most 80% of the second portion.

9. The method as claimed in claim 1, wherein a pump for feeding a fluid can be driven by the electric motor, wherein in the first state the pump is operated and in the second state at least the fluid which can be fed by the pump is heated.

10. The method as claimed in claim 1, wherein the electrical power which is used in the second state is at least 1% of a rated power of the electric motor.

11. A motor assembly, at least comprising an electric motor which has at least one first stator with at least three coils and a rotor with at least two magnets; wherein the first stator and the rotor are arranged one next to the other along an axial direction, wherein the coils are arranged one next to the other along a circumferential direction; wherein an electrically conductive body is arranged in a radial direction at least within or outside the first stator; wherein a specific electrical first resistance of the body is lower than a specific electrical second resistance of a core of a coil; wherein the electric motor is operable with a method as claimed in claim 1.

12. A pump assembly, at least comprising a motor assembly as claimed in claim 11 and additionally comprising a pump which can be driven by the electric motor in order to feed a fluid; wherein the body is arranged in such a way that the fluid which can be fed by the pump can be heated via the body.

Description

[0069] The invention and the technical field are explained in more detail below with reference to the figures. It is to be noted that the invention is not intended to be limited by the exemplary embodiments which are shown. In particular, it is, unless explicitly stated otherwise, also possible to extract partial aspects of the contents which are explained in the figures and combine them with other constituent parts and realizations from the present description and/or figures. Identical reference signs denote identical subject matters, so that if appropriate explanations from other figures can be additionally used. In the drawings, in each case schematically:

[0070] FIG. 1: shows an electric motor in a perspective view;

[0071] FIG. 2: shows a part of the electric motor according to FIG. 1 in a perspective view;

[0072] FIG. 3: shows the electric motor according to FIG. 1 in a motor assembly in a first perspective view;

[0073] FIG. 4: shows the motor assembly according to FIG. 3 in a second perspective view;

[0074] FIG. 5: shows the motor assembly according to FIGS. 3 and 4 in a perspective view in a second state;

[0075] FIG. 6: shows the motor assembly according to FIGS. 3 and 4 in a perspective view in a first state;

[0076] FIG. 7: shows a further embodiment variant of a motor assembly in a perspective view in an exploded illustration;

[0077] FIG. 8: shows a motor assembly according to FIG. 7 in a perspective view in section in a second state;

[0078] FIG. 9: shows the motor assembly according to FIG. 7 in a perspective view in section in an (other) second state; and

[0079] FIG. 10: shows a pump assembly in a perspective view.

[0080] FIG. 1 shows an electric motor 1 in a perspective view. The electric motor 1 comprises at least one first stator 2 and a rotor 6. The electric motor 1 is an axial flux motor, wherein the stator 2 and rotor 6 are arranged coaxially with respect to one another and one next to the other along an axial direction 9. The rotor 6 has alternately first magnets 7 (first pole) and second magnets 8 (second pole) along the circumferential direction 10. Here, six magnets 7, 8 (in each case three) are provided. The stator 2 has cores 15 which extend along the axial direction 9 through coils 3, 4, 5. Each coil 3, 4, 5 is connected to a phase of a three-phase current generator. The coils 3, 4, 5 are arranged along the circumferential direction 10 in the following sequence: first coil 3, second coil 4, third coil 5, first coil 3, etc. Here, nine coils 3, 4, 5 (in each case three) are provided.

[0081] Each core 15 extends starting from a first end 16 of the stator 2 up to a second end 17 of the stator 2, wherein the rotor 6 is arranged adjacent to the second end 17.

[0082] FIG. 2 shows a part of the electric motor 1 according to FIG. 1 in a perspective view. Reference is made to the statements relating to FIG. 1.

[0083] Here, the coils 3, 4, 5 are not illustrated.

[0084] FIG. 3 shows the electric motor 1 according to FIG. 1 in a motor assembly 20 in a first perspective view. FIG. 4 shows the motor assembly 20 according to FIG. 3 in a second perspective view. Reference is made to the statements relating to FIG. 1.

[0085] The motor assembly 20 comprises the electric motor 1 and an electrically conductive body 14 which is arranged in a radial direction 13 outside the first stator 2. A specific electrical first resistance of the body 14 is higher than a specific electrical second resistance of a core 15 of a coil 3, 4, 5. The electric motor 1 can be operated with the described method.

[0086] The body 14 extends along a circumferential direction 10 completely (in a radial direction 13 outside the cores 15 or the coils 3, 4, 5) and along an axial direction 9 (and the rotational axis 11 running parallel thereto) starting from the second end 17 of the stator 2 up to the first end 16 of the stator 2. The body 14 is in contact, at the first end 16 of the first stator 2, with the cores 15 of the coils 3, 4, 5. The body 14 extends at the first end 16 along the radial direction 13 to over the extent of the cores 15 (FIG. 4). The body 14 forms here a pot with a cylindrical section (starting from the second end 17 up to the first end 16) and a base (at the first end 16).

[0087] FIG. 5 shows the motor assembly 20 according to FIGS. 3 and 4 in a perspective view in a second state. Reference is made to the statements relating to FIGS. 3 and 4.

[0088] In the second state, the coils 3, 4, 5 are operated with an alternating current with the same phase. There is then no multi-phase current (that is to say no phase offset between the individual electric currents) present so that driving of the rotor 6 specifically does not occur. The alternating current causes an alternating magnetic field to be generated which can generate heat in the body 14 by means of the magnetic flux 22 which is generated and transmitting via induction.

[0089] The magnetic flux 22 is directed via the body 14 in such a way that the highest possible portion of the electrical (drive) power of the electric motor 1 can be converted into heat by the body 14. The body 14 directs the magnetic flux 22 starting from the second end 17 along the axial direction 9 up to the first end 16 and back again into the cores 15.

[0090] The illustrated arrows show the magnetic flux 22 which is generated with a common phase and is always of the same strength at a point in time.

[0091] FIG. 6 shows the motor assembly 20 according to FIGS. 3 and 4 in a perspective view in a first state. Reference is made to the statements relating to FIGS. 3 and 4.

[0092] In the first state, the coils 3, 4, 5 are operated with respective different phases of a three-phase current generator and the rotor 6 is made to rotate about the rotational axis 11 (rotational speed higher than zero revolutions per minute). The illustrated arrows show the magnetic flux 22 which differs in strength depending on the phase at a point in time. The magnetic flux 22 is directed here in particular via the rotor 6 and back to the cores 15 (of the coil 3, 4, 5 which is respectively operated with the same phase). A magnetic flux 22 in the body 15 is generated in particular with a negligible magnitude.

[0093] FIG. 7 shows a further embodiment variant of a motor assembly 20 in a perspective view in an exploded illustration.

[0094] The electric motor 1 here has a first stator 2 and a second stator 12, with nine coils 3, 4, 5 per stator 2, 12 (that is to say three first coils 3, three second coils 4 and three third coils 5 per stator 2, 12). The rotor 6 is arranged along the axial direction 9 between the first stator 2 and the second stator 12.

[0095] The motor assembly 20 has two bodies 14. Each body 14 extends starting from the second end 17 of a stator 2, 12 along the axial direction 9 and in a radial direction 13 outside the coils 3, 4, 5 up to the first end 16 of the respective stator 2, 12. Each body 14 extends at the first end 16 along the radial direction 13 to over the extent of the cores 15. Each body 14 forms a pot with a cylindrical section (starting from the second end 17 up to the first end 16) and a base (at the first end 16). The bodies 14 are in contact with one another via the end faces of the bodies 14 at the second ends 17 (see FIGS. 8 and 9).

[0096] FIG. 8 shows the motor assembly 1 according to FIG. 7 in a perspective view in section in a second state. Reference is made to the statements relating to FIG. 7.

[0097] In the second state, the coils 3, 4, 5 are operated with an alternating current with the same phase. There is then no multi-phase current (that is to say no phase offset between the individual electric currents) present so that driving of the rotor 6 specifically does not occur. The alternating current causes an alternating magnetic field to be generated which can generate heat in the (multi-part) body 14 by means of the magnetic flux 22 which is generated and transmitting via induction.

[0098] The magnetic flux 22 is directed via the body 14 in such a way that the highest possible portion of the electrical (drive) power of the electric motor 1 can be converted into heat by the body 14. The body 14 directs the magnetic flux 22 starting e.g. from a first end 16 of the second stator 12 firstly along the radial direction 13 and then along the axial direction 9 up to the first end 16 of the first stator 2 and there via the cores 15 of the first stator 2 along the axial direction 9 via the rotor 6 to the cores 15 of the second stator 12 and back again to the first end 16 of the second stator 12.

[0099] FIG. 9 shows the motor assembly according to FIG. 7 in a perspective view in section in an (other) second state. Reference is made to the statements relating to FIG. 8.

[0100] In contrast to FIG. 8, the magnetic flux 22 is directed here via just one stator 2, 12 in each case. The (multi-part) body 14 directs the magnetic flux 22 starting e.g. from a first end 16 of the second stator 12 firstly along the radial direction 13 and then along the axial direction 9 up to the second end 17 of the second stator 12 and there via the cores 15 of the second stator 12 along the axial direction 9 back again to the first end 16 of the second stator 12. The same applies to the first stator 2. The magnetic flux 22 is therefore directed starting e.g. from the first end 16 of the first stator 2 along the axial direction 9 via the cores 15 of the first stator 2 up to the second end 17 of the first stator 2 and subsequently via the body 14 along the axial direction 9 back again to the first end 16 of the first stator 2.

[0101] FIG. 10 shows a pump assembly 21 in a perspective view. The pump assembly 21 comprises an electric motor 1 with a first stator 2 (with coils 3, 4, 5) and a rotor 6 (with magnets 7, 8) as well as additionally a pump 18 which can be driven by the electric motor 1 in order to feed a fluid 19. The body 14 is formed here by the carrier material of the rotor 6 which bears the magnets 7, 8. This assembly is particularly advantageous if the body 14 is heated by means of high-frequency excitation.

[0102] However, it is preferred that the body 14 is arranged as illustrated in FIGS. 3 to 9, wherein the fluid 19 is connected to the body via a connection which is as thermally conductive as possible.

LIST OF REFERENCE SIGNS

[0103] 1 Motor [0104] 2 First stator [0105] 3 First coil [0106] 4 Second coil [0107] 5 Third coil [0108] 6 Rotor [0109] 7 First magnet [0110] 8 Second magnet [0111] 9 Axial direction [0112] 10 Circumferential direction [0113] 11 Rotational axis [0114] 12 Second stator [0115] 13 Radial direction [0116] 14 Body [0117] 15 Core [0118] 16 First end [0119] 17 Second end [0120] 18 Pump [0121] 19 Fluid [0122] 20 Motor assembly [0123] 21 Pump assembly [0124] 22 Magnetic flux