Combination Radial/Axial Electromagnetic Actuator

• US 20110163622A1
• Filed: 01/06/2011
• Published: 07/07/2011
• Est. Priority Date: 01/06/2010
• Status: Active Grant

• Current Assignee: Calnetix Technologies, LLC (General Electric Company)
• Original Assignee: Calnetix Technologies, LLC (General Electric Company)
• Inventors: Filatov, Alexei V., Hawkins, Lawrence A.
• Granted Patent: US 8,796,894 B2
• Time in Patent Office: Days
• US Class Current: 310/90.5
• CPC Class Codes: F16C 2360/44 Centrifugal pumps in general F04D
• CPC Class Codes: F16C 2380/26 Dynamo-electric machines or combinations therewith, e.g. electro-motors and generators in general H02K
• CPC Class Codes: F16C 32/0465 with permanent magnets provided in the magnetic circuit of the electromagnets
• CPC Class Codes: F16C 32/0485 with active support of three degrees of freedom
• CPC Class Codes: H02K 7/09 with magnetic bearings

Abstract

An electromagnetic actuator includes a body and first and second poles residing apart from the body. The first and second poles communicate magnetic flux across a gap with opposing end facing surfaces of the body. The body, the first pole, and the second pole are magnetically coupled and define an axial magnetic control circuit. A plurality of radial poles reside apart from the body, adjacent a lateral facing surface of the body, and communicate magnetic fluxes with the lateral facing surface. The body and the plurality of radial poles define a plurality of radial magnetic control circuits. The plurality of radial poles communicate magnetic fluxes with the lateral facing surface and at least one of the first pole or the second pole, and the body, the plurality of radial poles, and at least one of the first pole or the second pole define a magnetic bias circuit.

Claims

1. An electromagnetic actuator comprising:

a body having a rotational axis;

a first pole residing apart from the body, the first pole adjacent a first end facing surface of the body and adapted to communicate magnetic flux across a gap with the first end facing surface of the body;

a second pole residing apart from the body, the second pole adjacent a second end facing surface of the body and adapted to communicate magnetic flux with the second end facing surface of the body, the body, the first pole, and the second pole magnetically coupled and defining an axial magnetic control circuit;

a plurality of radial poles residing apart from the body, the plurality of radial poles adjacent a lateral facing surface of the body and adapted to communicate magnetic fluxes with the lateral facing surface of the body, the body and the plurality of radial poles defining a plurality of radial magnetic control circuits, the plurality of radial poles adapted to communicate magnetic fluxes with the lateral facing surface of the body and at least one of the first pole or the second pole, and the body, the plurality of radial poles, and at least one of the first pole or the second pole defining a magnetic bias circuit.

2. The actuator of claim 1 wherein the end facing surface of the body is orthogonal to the rotational axis.

3. The actuator of claim 1 wherein the body incorporates a magnetically permeable actuator target, the actuator target adapted to communicate a magnetic flux.

4. The electromagnetic actuator of claim 1, further comprising a magnetic element configured to produce magnetic bias flux in the magnetic bias circuit.

5. The electromagnetic actuator of claim 1, further comprising an axial coil adapted to produce a magnetic flux in the axial magnetic control circuit and a plurality of radial coils adapted to produce magnetic fluxes in the plurality of radial magnetic control circuits.

6. The actuator of claim 5 wherein the magnetic flux entering the end facing surface of the body exerts an axial force on the body and the magnetic fluxes entering the lateral surface of the body exert radial forces on the body.

7. The actuator of claim 6 wherein the axial force is proportional to the magnetic flux in the axial magnetic control circuit and the radial forces are proportional to the magnetic fluxes in the radial magnetic control circuits.

8. The electromagnetic actuator of claim 1 wherein the plurality of radial poles is defined by a first annular lamination and a second annular lamination, the first and second annular laminations defining an annular lamination stack coaxial to the rotational axis.

9. The electromagnetic actuator of claim 8 wherein the first and the second annular laminations comprise a magnetically permeable material.

10. The electromagnetic actuator of claim 8 wherein the first and the second annular laminations are electrically isolated from each other.

11. The electromagnetic actuator of claim 7, wherein the first annular lamination is a first disjointed annular element defining a first air gap between disjoined segments of the annular element and the second annular lamination is a second disjointed annular element defining a second air gap between disjoined segments of the second annular element.

12. The electromagnetic actuator of claim 11, wherein the first air gap resides misaligned from the second air gap in the annular lamination stack.

13. An electric machine system comprising:

a stator;

a rotor having a rotational axis configured to move relative to the stator;

an electromagnetic actuator subassembly comprising;

a cylindrical actuator target rigidly mounted on the rotor;

a first axial pole residing apart from the actuator target, the first axial pole adjacent a first end facing surface of the actuator target and adapted to communicate magnetic flux across a gap with the first end facing surface of the actuator target;

a second axial pole residing apart from the actuator target, the second axial pole adjacent a second end facing surface of the actuator target and adapted to communicate magnetic flux with the second end facing surface of the actuator target;

an axial back-iron magnetically linking the first axial pole and the second axial pole;

the actuator target, the first axial pole, the second axial pole and the axial back-iron are magnetically coupled and defining an axial magnetic control circuit;

an axial control conductive coil adapted to produce a magnetic flux in the axial magnetic control circuit;

a magnetically permeable annual element located concentric to the rotational axis and including a plurality of radial poles and an electrically isolating radial gap interrupting a conductive path around the rotational axis, the magnetically permeable annual element including a plurality of radial poles residing apart from the actuator target, the plurality of radial poles adjacent a lateral facing surface of the actuator target and adapted to communicate magnetic fluxes with the lateral facing surface of the actuator target, the actuator target and the plurality of radial poles defining a plurality of radial magnetic control circuits, the plurality of radial poles adapted to communicate magnetic fluxes with the lateral facing surface of the actuator target and at least one of the first axial pole or the second axial pole, the actuator target, the plurality of radial poles and at least one of the first axial pole or the second axial pole defining a magnetic bias circuit;

radial control conductive coils wound around the radial poles and adapted to produce a magnetic flux in the radial magnetic control circuit;

one or more position sensors configured to sense a position of the actuator target; and

at least one control electronics package configured to control the electric currents in the axial control conductive coil and radial control conductive coils.

14. The system of claim 13 wherein the rotor is coupled to a driven load, the driven load comprising at least one of a flywheel, a generator, or an expander.

15. The system of claim 13 wherein the rotor is coupled to a driver, the driver comprising at least one of a motor, an engine, or a turbine.

16. The system of claim 13 wherein the magnetic fluxes exert electromagnetic forces on the actuator target.

17. The system of claim 16 wherein the electronic control package is further configured to energize the control coils around each of the plurality of radial poles with control currents in response to changes of signals from the position sensors so that the rotor is supported by electromagnetic forces without a mechanical contact with the stator.

18. A method for exerting axial and radial forces on a cylindrical body having a symmetry axis, the method comprising:

communicating a first bias magnetic flux through a first axial facing surface of the body;

communicating a second bias magnetic flux through a second axial facing surface of the body;

communicating combined the first and the second bias magnetic fluxes through a lateral surface of the cylindrical body;

communicating an axial control magnetic flux through the first and the second axial facing surfaces of the body;

communicating a radial control magnetic flux diagonally across the body by means of a stationary radial pole assembly located around the body and separated from it;

suppressing electrical currents in the stationary radial pole assembly by introducing isolating interrupts of the conductive paths.

19. The method of claim 18 in which the stationary radial pole assembly is composed of magnetically-permeable laminations made of electrical steel stacked together along the body symmetry axis.

20. The method of claim 19 in which the isolating interrupts are introduced in each lamination.

21. The method of claim 20 in which circumferential locations of the insolating interrupts vary from lamination to lamination across the lamination stack.