Generating radial electromagnetic forces

• US 9,683,601 B2
• Filed: 03/14/2013
• Issued: 06/20/2017
• Est. Priority Date: 03/14/2013
• 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:
  US13/831,213
• Publication Number:
  US 20140265689A1
• Time in Patent Office: 1,559 Days
• Field of Search: 310 905, 310153, 310181, 310 49
• CPC Class Codes: F16C 32/0414 with facing axial projections
• CPC Class Codes: F16C 32/0463 with electromagnetic bias, e.g. by extra bias windings
• CPC Class Codes: F16C 32/0465 with permanent magnets provided in the magnetic circuit of the electromagnets
• CPC Class Codes: F16C 32/048 with active support of two degrees of freedom, e.g. radial magnetic bearings

Abstract

An electromagnetic actuator can exert a radial electromagnetic force on a body that is configured to rotate about a rotational axis. The actuator includes a radial control magnetic pole assembly that includes radial control poles adjacent to and spaced apart by air gaps from the body. The actuator includes a permanent magnet (PM) magnetized along the axis, having one pole in contact with an axial face of the assembly and located proximate to a lateral surface of the body. The PM is magnetically coupled to the body in a non-contact manner resulting in a bias magnetic flux in the air gaps. The actuator includes a control coil around the radial control poles located radially outwards from the PM. Electrical current in the coils generates control magnetic flux in air gaps. The non-uniform net magnetic flux distribution around the body results in a radial electromagnetic force exerted on the body.

Claims

1. An electromagnetic actuator comprising:

a body having a rotational axis;

a radial control magnetic pole assembly concentric with the rotational axis and comprising at least three radial control poles adjacent to and separated from a lateral surface of the body by radial control air gaps, the radial control poles configured to communicate magnetic flux with the lateral surface of the body, the radial control poles magnetically coupled to each other on an outer periphery of the radial control pole assembly, the radial control poles magnetically coupled to the body forming a plurality of radial control magnetic circuits configured to propagate radial control magnetic fluxes in planes orthogonal to the rotational axis;

a first permanent magnet magnetized along the rotational axis, the first permanent magnet having a first magnetic pole of the first permanent magnet residing on a first axially facing surface of the radial control magnetic pole assembly, located proximate of the lateral surface of the body and separated from the body by a first magnet air gap;

a second permanent magnet magnetized along the rotational axis, the second permanent magnet having a first magnetic pole of the second permanent magnet in contact with a second axial face of the radial control magnetic pole assembly which is opposite the first axially facing surface of the radial control magnetic pole assembly, the second permanent magnet located in a close proximity of the lateral surface of the body and separated from the body by a second magnet air gap, the first magnetic pole of the second permanent magnet in contact with the second axial face of the radial control magnetic pole assembly is of the same polarity as the first magnetic pole of the first permanent magnet;

a first magnet pole piece in contact with a second magnetic pole of the first permanent magnet, separated from the body by a first magnet pole piece radial air gap and configured to communicate magnetic flux with the lateral surface of the body, the body, the radial control magnetic pole assembly, the first permanent magnet and the first magnet pole piece defining a first bias magnetic circuit, wherein the first permanent magnet generates a bias flux in the first bias magnetic circuit, the bias magnetic flux emanates from the second magnetic pole of the first permanent magnet, enters the first magnet pole piece, propagates radially from the first magnet pole piece into the body across the first magnet pole piece radial air gap, radially exits the body across the radial control pole airgaps, and returns into the first magnetic pole of the first permanent magnet through the radial control magnetic pole assembly;

a second magnet pole piece in contact with a second magnetic pole of the second permanent magnet;

the body, the radial magnetic pole assembly, the second permanent magnet, and the second magnet pole piece defining a second bias magnetic circuit, wherein the second permanent magnet generates a second bias magnetic flux in the second bias magnetic circuit, the second bias flux emanates from the second magnetic pole of the second permanent magnet, enters the second magnet pole piece, propagates radially from the second magnet pole piece into the body across the second magnet pole piece radial air gap, radially exits the body across the radial control pole airgaps and returns into the first magnetic pole of the second permanent magnet thru the radial control magnetic pole assembly; and

a control coil wound around each of the radial control poles located radially outwards from the first permanent magnet and configured to produce control magnetic flux in the radial control magnetic control circuits.

2. The actuator of claim 1, wherein the bias magnetic flux and the control magnetic flux entering the lateral surface of the body exert radial forces on the body.

3. The actuator of claim 2, wherein the radial forces are proportional to the control magnetic flux in the radial magnetic control circuits.

4. The actuator of claim 1, wherein the control magnetic flux is produced by a control current in the excitation coil, the control current controllable to affect a total magnetic flux in the control magnetic circuit.

5. The actuator of claim 1, further comprising a third permanent magnet magnetized along the rotational axis and a fourth permanent magnet magnetized along the rotational axis, the third permanent magnet and the fourth permanent magnet integrated into the body, wherein a first magnetic pole of the first permanent magnet is axially aligned with a first magnetic pole of the third permanent magnet, wherein a polarity of the first magnetic pole of the first permanent magnet is opposite a polarity of the first magnetic pole of the third permanent magnet, wherein the third permanent magnet is added to the first bias magnetic circuit and the first bias magnetic flux is generated by both the first permanent magnet and the third permanent magnet in an additive manner,

wherein a first magnetic pole of the second permanent magnet is axially aligned with a first magnetic pole of the fourth permanent magnet, wherein a polarity of the first magnetic pole of the second permanent magnet is opposite a polarity of the first magnetic pole of the fourth permanent magnet, wherein the fourth permanent magnet is added to the second bias magnetic circuit and the second bias magnetic flux is generated by both the second permanent magnet and the fourth permanent magnet in an additive manner.

6. The actuator of claim 1, wherein a portion of the body aligned with the radial control magnetic pole assembly along the rotational axis of the body is continuous and has a circular cross-section.

7. An electromagnetic actuator comprising:

a body having a rotational axis;

a radial control magnetic pole assembly concentric with the rotational axis and comprising at least three radial control poles adjacent to and separated from a lateral surface of the body by radial control air gaps, the radial control poles configured to communicate magnetic flux with the lateral surface of the body, the radial control poles magnetically coupled to each other on an outer periphery of the radial control pole assembly, the radial control poles magnetically coupled to the body forming a plurality of radial control magnetic circuits configured to propagate radial control magnetic fluxes in planes orthogonal to the rotational axis;

a first permanent magnet magnetized along the rotational axis, the first permanent magnet having a first magnetic pole residing on an axially facing surface of the radial control magnetic pole assembly, located proximate of the lateral surface of the body and separated from the body by a magnet air gap;

a second permanent magnet magnetized along the rotational axis and integrated into the body, a first magnetic pole of the first permanent magnet is axially aligned with a first magnetic pole of the second permanent magnet, wherein a polarity of the first magnetic pole of the first permanent magnet is opposite a polarity of the first magnetic pole of the second permanent magnet, wherein the second permanent magnet is added to the bias magnetic circuit and the bias magnetic flux is generated by both the first permanent magnet and the second permanent magnet in an additive manner;

a magnet pole piece in contact with a second magnetic pole of the first permanent magnet, separated from the body by a magnet pole piece radial air gap and configured to communicate magnetic flux with the lateral surface of the body;

the body, the radial control magnetic pole assembly, the first permanent magnet and the magnet pole piece defining a bias magnetic circuit, wherein the first permanent magnet generates a bias flux in the bias magnetic circuit, the bias magnetic flux emanates from the second magnetic pole of the first permanent magnet, enters the magnet pole piece, propagates radially from the magnet pole piece into the body across the magnet pole piece radial air gap, radially exits the body across the radial control pole airgaps, and returns into the first magnetic pole of the first permanent magnet through the radial control magnetic pole assembly; and

a control coil wound around each of the radial control poles located radially outwards from the first permanent magnet and configured to produce control magnetic flux in the radial control magnetic control circuits.

8. The actuator of claim 7, wherein the bias magnetic flux and the control magnetic flux entering the lateral surface of the body exert radial forces on the body.

9. The actuator of claim 8, wherein the radial forces are proportional to the control magnetic flux in the radial magnetic control circuits.

10. The actuator of claim 7, wherein the control magnetic flux is produced by a control current in the excitation coil, the control current controllable to affect a total magnetic flux in the control magnetic circuit.

11. The actuator of claim 7, wherein a portion of the body aligned with the radial control magnetic pole assembly along the rotational axis of the body is continuous and has a circular cross-section.