Combined passive bearing element/generator motor

• US 6,111,332 A
• Filed: 02/03/1998
• Issued: 08/29/2000
• Est. Priority Date: 02/03/1998
• Status: Expired due to Term

• Current Assignee: Lawrence Livermore National Security LLC (Government of the United States of America)
• Original Assignee: Regents of the University of California (University of California)
• Inventors: Post, Richard F.
• Primary Examiner(s): LABALLE, CLAYTON E
• Application Number:
  US09/017,930
• Time in Patent Office: 938 Days
• Field of Search: 310/90.5, 310/113, 310/156, 310/112, 310/74
• US Class Current: 310/90.5
• CPC Class Codes: F16C 2300/32 Horizontal, e.g. bearings for supporting a horizontal shaft
• 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 32/0412 for radial load mainly
• CPC Class Codes: H02K 7/09 with magnetic bearings

Abstract

An electric machine includes a cylindrical rotor made up of an array of permanent magnets that provide a N-pole magnetic field of even order (where N=4, 6, 8, etc.). This array of permanent magnets has bars of identical permanent magnets made of dipole elements where the bars are assembled in a circle. A stator inserted down the axis of the dipole field is made of two sets of windings that are electrically orthogonal to each other, where one set of windings provides stabilization of the stator and the other set of windings couples to the array of permanent magnets and acts as the windings of a generator/motor. The rotor and the stator are horizontally disposed, and the rotor is on the outside of said stator. The electric machine may also include two rings of ferromagnetic material. One of these rings would be located at each end of the rotor. Two levitator pole assemblies are attached to a support member that is external to the electric machine. These levitator pole assemblies interact attractively with the rings of ferromagnetic material to produce a levitating force upon the rotor.

Claims

1. An electric machine, comprising:

a cylindrical rotor comprising an array of permanent magnets that provide an N-pole magnetic field of even order, wherein N=4, 6, 8, etc., wherein said array of permanent magnets comprise bars of identical permanent magnets assembled in a circle, wherein said bars are dipole elements, wherein each bar of said bars has a vector direction of magnetization that rotates at N times the rate as that of a vector rotating about said circle pointing from the center of said N-pole field to the center of said elements; and

a stator inserted down the axis of said N-pole field, wherein said stator comprises first set of windings and second set of windings, wherein said first set of windings and said second set of windings are electrically orthogonal in action to each other, wherein said first set of windings provides radial stabilization of said stator and said second set of windings couples to said array of permanent magnets and acts as the windings of a generator/motor, wherein said rotor and said stator are horizontally disposed, wherein said rotor is on the outside of said stator.

2. The electric machine of claim 1, further comprising two rings of ferromagnetic material, wherein a first ring of said two rings is located at a first end of said rotor, wherein a second ring of said two rings is located at a second end of said rotor;

and

two levitator pole assemblies fixedly attached to a support member external to said electric machine, wherein a first levitator pole assembly of said two levitator pole assemblies magnetically interacts attractively with said first ring to produce a levitating force upon said rotor, wherein a second levitator pole assembly of said two levitator pole assemblies magnetically interacts attractively with said second ring to produce a levitating force upon said rotor.

3. The electric machine of claim 1, wherein a voltage induced in a first half of said first set of windings to exactly cancels another voltage induced in a second half of said first set of windings so that no current flows when the axis of said array of permanent magnets coincides with the axis of symmetry of said first set of windings, wherein voltage cancellation no longer occurs when the axes are displaced from each other and current flows, resulting in a centering action.

4. The electric machine of claim 1, wherein said, second set of windings are interconnected so that their voltages add in phase at an output lead, so that power can be drawn from them, or they can be used as motor windings to spin up said cylindrical rotor to which they are attached.

5. The electric machine of claim 4, wherein said second set of windings are configured to produce a single-phase output.

6. The electric machine of claim 4, wherein said second set of windings are configured to produce a multiple-phase output.

7. The electric machine of claim 1, wherein said cylindrical rotor further comprises a cylindrical ring of high-strength material comprising said array of permanent magnets on its inner surface.

8. The electric machine of claim 7, further comprising a thin-walled stationary vacuum barrier comprising insulating material disposed between the inner surface of said array of permanent magnets and the outer surface of the stator windings.

9. The electric machine of claim 2, wherein said two rings of ferromagnetic material comprise laminated ferromagnetic material.

10. The electric machine of claim 2, wherein said two rings of ferromagnetic material comprise bonded ferromagnetic powder (to minimize losses from eddy-currents).

11. The electric machine of claim 1, wherein said rotor comprises a first tapered portion at a first end and a second tapered portion at a second end, wherein said array comprises a first Halbach array on said first tapered portion, wherein said array comprises a second Halbach array on second tapered portion, wherein the azimuthal phase of said first Halbach array is displaced by 180 degrees with respect to said second Halbach array, wherein said stator comprises a third set of windings incorporated onto said stator to provide additional axial centering forces, wherein said third set of windings is configured to link no net flux either in the centered position or for translations of the axis of rotation perpendicular to that axis but to link flux upon axial displacements to provide restoring forces that re-center the rotating system axially.

12. The electric machine of claim 1, wherein said rotor comprises a first tapered portion at a first end and a second tapered portion at a second end, wherein said array comprises a first Halbach array on said first tapered portion, wherein said array comprises a second Halbach array on second tapered portion, wherein the azimuthal phase of said first Halbach array is not displaced with respect to said second Halbach array, wherein said stator comprises a third set of windings incorporated onto said stator to provide additional axial centering forces, wherein said third set of windings is configured to link no net flux either in the centered position or for translations of the axis of rotation perpendicular to that axis but to link flux upon axial displacements to provide restoring forces that re-center the rotating system axially.

13. The electric machine of claim 1, wherein said first set of windings comprise rectangular "window frames" and lie transversely across said stator.

14. The electric machine of claim 1, wherein said stator comprises a stator support structure, wherein said first set of windings are lap-wound and lie on the surface of said stator support structure.

15. An electric machine, comprising:

a cylindrical rotor comprising an array of permanent magnets that provide an N-pole magnetic field of even order, wherein N=4, 6, 8, etc., wherein said array of permanent magnets comprises bars of identical permanent magnets assembled in a circle, wherein said bars are dipole elements, wherein each bar of said bars has a vector direction of magnetization that rotates at N times the rate as that of a vector rotating about said circle pointing from the center of said N-pole field to the center of said elements, wherein the direction of rotation of the dipole elements relative to the vector rotating about said circle is such that said N-pole field is maximized outside of said array; and

a stator surrounding said N-pole field, wherein said stator comprises a first set of windings and a second set of windings, wherein said first set of windings and said second set of windings are electrically orthogonal to each other, wherein said first set of windings provides stabilization of said stator and said second set of windings couples to said array of permanent magnets and acts as the windings of a generator/motor, wherein said rotor and said stator are horizontally disposed, wherein said stator is on the outside of said rotor.