Arrangement of axial and radial electromagnetic actuators

• US 9,531,236 B2
• Filed: 06/01/2012
• Issued: 12/27/2016
• Est. Priority Date: 06/02/2011
• Status: Active Grant

• Current Assignee: Calnetix Technologies, LLC (General Electric Company)
• Original Assignee: Calnetix Technologies, LLC (General Electric Company)
• Inventors: Filatov, Alexei
• Primary Examiner(s): Kim, John K
• Application Number:
  US13/486,194
• Publication Number:
  US 20120306305A1
• Time in Patent Office: 1,670 Days
• Field of Search: 310/12.14, 310/90.5
• US Class Current: 1/1
• CPC Class Codes: F16C 32/0463 with electromagnetic bias, e.g. by extra bias windings
• CPC Class Codes: H02K 7/09 with magnetic bearings

Abstract

Systems, methods, and devices for generating electromagnetic forces may involve generating an axial control magnetic flux in an axial control magnetic circuit comprising a first axial pole, a second axial pole, and an axial actuator target, the axial actuator target coupled to a body having a rotational axis. A radial control flux can be generated in a radial control magnetic circuit comprising a first radial pole, a second radial pole, and a radial actuator target. An electrical compensation current can be applied to an electrical bias flux leveling coil to cancel or nearly cancel any changes of the magnetic flux leaking from either the first or the second axial poles into the radial poles, electrical bias flux leveling coil wound around the rotational axis and located axially between the radial poles and the closest of the first or the second axial poles.

Claims

1. An electromagnetic actuator system comprising:

an axial actuator system and a radial actuator system separated by an axial gap along a rotational axis;

the axial actuator system comprising;

a stationary first axial pole and a stationary second axial pole, the first and the second axial poles magnetically coupled to each other;

a body configured to rotate about the rotational axis, the first axial pole adjacent to and separated from a first end-facing surface of the body and the second axial pole adjacent to and separated from a second end-facing surface of the body, the first and second axial poles and the body configured to communicate magnetic flux;

an electrical axial control coil configured, when energized with a first current, to induce axial control magnetic flux flowing between the first axial pole and the first end-facing surface of the body as well as the second axial pole and the second end-facing surface of the body, the axial gap to cause a portion of the axial control magnetic flux to leak from the axial actuator system to the radial actuator system;

the radial actuator system comprising a plurality of radial poles positioned around a radial facing surface of the body, separated from the radial facing surface of the body and configured to communicate magnetic flux with the body;

an electrical bias flux leveling coil wound around the rotational axis, the electrical bias flux leveling coil being located axially between the plurality of radial poles and the closest of either the first or the second axial poles, the electrical bias flux leveling coil separate and electrically independent from the electrical axial control coil, and configured to produce magnetic flux in the plurality of radial poles, the body, and the first and second axial poles, the magnetic flux produced by the electrical bias flux leveling coil configured, when energized with a second current, to counteract the portion of the axial control magnetic flux leaking from the axial actuator system to the radial actuator system.

2. The electromagnetic actuator system of claim 1, wherein the plurality of radial poles are arranged radially outside of the body.

3. The electromagnetic actuator system of claim 1, wherein the radial actuator system comprises:

a stationary dead pole placed axially between the electrical bias flux leveling coil and the plurality of radial poles, the dead pole circumferentially surrounding the radial facing surface of the body, the dead pole separated from the radial facing surface of the body, the dead pole configured to communicate magnetic flux with the body; and

an axially magnetized bias permanent magnet placed between the dead pole and the plurality of radial poles, the bias permanent magnet magnetically connected to the dead pole and the plurality of radial poles, wherein the bias permanent magnet generates a bias magnetic flux flowing through the dead pole into the body and from the body into the plurality of radial poles,

wherein the magnetic flux produced by the electrical bias flux leveling coil is configured to maintain the bias magnetic flux constant by counteracting the portion of the axial control magnetic flux leaking from the axial actuator system to the radial actuator system.

4. The electric machine system of claim 2, wherein the radial actuator system further comprises:

a stationary dead pole placed axially between the electrical bias flux leveling coil and the plurality of radial poles, the dead pole circumferentially surrounding the radial facing surface of the body, the dead pole separated from the radial facing surface of the body, the dead pole configured to communicate magnetic flux with the body; and

an axially magnetized bias permanent magnet placed between the dead pole and the plurality of radial poles, the bias permanent magnet magnetically connected to the dead pole and the plurality of radial poles, wherein the bias permanent magnet generates a bias magnetic flux flowing through the dead pole into the body and from the body into the plurality of radial poles,

wherein the magnetic flux produced by the electrical bias flux leveling coil is configured to maintain the bias magnetic flux constant by counteracting the portion of the axial control magnetic flux leaking from the axial actuator system to the radial actuator system.

5. The electromagnetic actuator system of claim 1, further comprising:

an axial control current source configured to provide the first current to induce the axial control magnetic flux in the electrical axial control coil, wherein the portion of the axial control magnetic flux leaking from the axial actuator system to the radial actuator system is affected by an axial position of the body; and

a compensation current source configured to provide the second current to induce the magnetic flux configured to counteract the portion of the axial control magnetic flux leaking from the axial actuator system to the radial actuator system, wherein the second current is a function of the first current and the axial position, and wherein the axial control current source is separate and electrically independent from the compensation current source.

6. The electromagnetic actuator system of claim 5, wherein the compensation current source comprises an amplifier.

7. A method of generating axial and radial electromagnetic forces, the method comprising:

generating, with an axial control current, an axial control magnetic flux in an axial control magnetic circuit comprising a first axial pole, a second axial pole, and an axial actuator target, the axial actuator target coupled to a body having a rotational axis and having a first end-facing surface and a second end-facing surface, the first and second end-facing surfaces orthogonal or substantially orthogonal to the rotational axis, the first axial pole and the second axial pole adjacent to and separated from the first and second end-facing surfaces, the first axial pole and the second axial pole magnetically coupled to each other;

generating a radial control flux in a radial control magnetic circuit comprising a first radial pole, a second radial pole and a radial actuator target, the radial actuator target having a cylindrical surface concentric or substantially concentric with the rotational axis, the first radial pole and the second radial pole positioned around the cylindrical surface of the radial actuator target and separated from the cylindrical surface of the radial actuator target, the first and the second radial poles magnetically coupled to each other, wherein the axial control magnetic circuit and the radial control magnetic circuit are separated by an axial gap along the rotational axis, the axial gap to cause a portion of the axial control magnetic flux to leak from the axial control magnetic circuit to the radial control magnetic circuit, wherein the portion of the axial control magnetic flux to leak from the axial control magnetic circuit to the radial control magnetic circuit being affected by the axial control current and an axial position of the body, wherein an electrical bias flux leveling coil is located axially between the radial poles and the closest of the first or the second axial poles and wound around the rotational axis, wherein the electrical bias flux leveling coil is located separately and electrically independently from an electrical axial control coil configured to induce the axial control magnetic flux; and

generating a magnetic flux by energizing the electrical bias flux leveling coil with an electrical compensation current that is separate and electrically independent of the axial control current, the magnetic flux to cancel or nearly cancel the portion of the axial control magnetic flux leaking from the axial control magnetic circuit to the radial control magnetic circuit, wherein the electrical compensation current is a function of the axial control current and the axial position.

8. The method of claim 7, further comprising:

placing a dead pole axially between the electrical bias flux leveling coil and the plurality of radial poles, the dead pole circumferentially surrounding the cylindrical surface concentric or substantially concentric with the rotational axis, the dead pole separated from the cylindrical surface, the dead pole configured to communicate magnetic flux with the body; and

placing an axially magnetized bias permanent magnet between the dead pole and the plurality of radial poles, the bias permanent magnet magnetically connected to the dead pole and the plurality of radial poles, wherein the bias permanent magnet generates a bias magnetic flux flowing through the dead pole into the body and from the body into the plurality of radial poles,

wherein the magnetic flux produced by the electrical bias flux leveling coil is configured to maintain the bias magnetic flux constant by canceling or nearly canceling the portion of the axial control magnetic flux leaking from the axial actuator system to the radial actuator system.

9. The electric machine system of claim 7, wherein the compensation current source comprises an amplifier.

10. The method of claim 7, wherein generating the magnetic flux by energizing the electrical bias flux leveling coil with the electrical compensation current comprises generating the compensation current using a separate amplifier.

11. An electric machine system comprising:

a stator;

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

an axial actuator system and a radial actuator system separated by an axial gap along the rotational axis;

the axial actuator system comprising;

a stationary first axial pole and a stationary second axial pole, the first and the second axial poles are magnetically coupled to each other,

an axial actuator target firmly attached to the rotor, the first axial pole adjacent to and separated from a first end-facing surface of the axial actuator target and the second axial pole adjacent to and separated from a second end-facing surface of the axial actuator target, the first and second axial poles and the axial actuator target configured to communicate magnetic flux;

an electrical axial control coil configured to induce axial control magnetic flux flowing between the first axial pole and the first end-facing surface of the axial actuator target as well as the second axial pole and the second end-facing surface of the axial actuator target; and

an axial control current source configured to provide an axial control current to induce the axial control magnetic flux in the electrical axial control coil;

the radial actuator system comprising;

a plurality of radial poles,

a radial actuator target firmly attached to the rotor, the radial poles positioned around a radial facing surface of the radial actuator target, separated from the radial facing surface of the radial actuator target, the radial poles are further configured to communicate magnetic flux with the radial actuator target;

an electrical radial control coil configured to induce radial control magnetic flux flowing between the radial poles and the peripheral surface of the radial actuator target,

wherein the axial gap causes a portion of the axial control magnetic flux to leak from the axial actuator system to the radial actuator system;

an electrical bias flux leveling coil wound around the rotational axis, the electrical bias flux leveling coil separate and electrically independent from the electrical axial control coil, the electrical bias flux leveling coil located axially between the radial poles and the closest of either the first or the second axial poles and configured to produce magnetic flux in the one or more radial poles, a body, and the first and second axial poles, the magnetic flux produced by the electrical bias flux leveling coil configured to counteract the portion of the axial control magnetic flux leaking from the axial actuator system to the radial actuator system, wherein the portion of the axial control magnetic flux that leaks from the axial actuator system to the radial actuator system is a function of the axial control current and an axial position of the body; and

a compensation current source configured to provide an electrical compensation current to induce the magnetic flux configured to counteract the portion of the axial control magnetic flux leaking from the axial actuator system to the radial actuator system, wherein the electrical compensation current is a function of the axial control current and the axial position of the body, and wherein the axial control current source is separate and electrically independent from the compensation current source.

12. The electric machine system of claim 11, wherein the rotor is coupled to an impeller.

13. The electric machine system of claim 11, wherein the rotor is coupled to a driver, the driver comprising at least one of a motor, an engine, or a turbine.

14. The electric machine system of claim 11, wherein an electronic control package is configured to control the axial and radial control magnetic fluxes by energizing electrical axial and radial control coil with control currents.

15. The electric machine system of claim 14, wherein the magnetic fluxes exert electromagnetic forces on the actuator target.

16. The electric machine system of claim 15, wherein an electronic control package is further configured to energize the electrical axial control coil and the electrical radial control coil with control currents in response to changes of signals from position sensors so that the rotor is supported by electromagnetic forces without a mechanical contact with the stator.