Superconducting rotating machines with stationary field coils

1. A machine comprising:

a shaft adapted to rotate about a longitudinal axis of the shaft, the shaft comprising a magnetic material;

a rotor assembly rotationally engaged with the shaft, the rotor assembly comprising a pair of rotor disks comprising a magnetic material, each of the rotor disks comprising a plurality of magnetic poles, the magnetic poles being spaced apart circumferentially, the rotor disks being coupled to the shaft for rotation about the shaft and generation of a rotating permeance wave; and

a stator assembly comprising a plurality of armature windings disposed between the rotor disks and defining an air core stator, and a stationary superconducting field coil disposed between the air core stator and the shaft,

wherein the stationary superconducting field coil is configured as a stationary magneto-motive force (MMF) source for the rotating permeance wave produced by the rotor assembly to produce a rotating magnetic field.

2. The machine of claim 1 , wherein the rotating magnetic field is characterized by a flux loop that extends along the shaft, along the rotor disks and across the air core stator to supply a time varying magnetic flux to the armature windings.

3. The machine of claim 2 , wherein the magnetic poles are separated by air spaces.

4. The machine of claim 2 , wherein each of the rotor disks further comprises a non-magnetic material forming a plurality of non-magnetic regions separating the magnetic poles.

5. The machine of claim 2 , wherein the magnetic material employed in the shaft is characterized by a saturation value of at least about 1.8 Tesla.

6. The machine of claim 5 , wherein the magnetic material employed in the shaft comprises an iron-cobalt alloy, and wherein the magnetic material employed in the rotor disks is selected from the group consisting of iron-cobalt alloys, magnetic steel, silicon iron and combinations thereof.

7. The machine of claim 2 , wherein each of the rotor disks has the same number of magnetic poles, and wherein the magnetic poles on a first one of the rotor disks are aligned with the magnetic poles on a second one of the rotor disks.

8. The machine of claim 1 , wherein the stationary superconducting field coil is configured to generate a peak field value in the machine of at least about 1.5 Tesla.

9. The machine of claim 1 , wherein the armature windings comprise superconducting armature windings.

10. The machine of claim 1 , further comprising a plurality of rotor and stator assemblies arranged along the shaft.

11. A machine comprising:

a shaft adapted to rotate about a longitudinal axis of the shaft, the shaft comprising a magnetic material;

a rotor assembly rotationally engaged with the shaft, the rotor assembly comprising a pair of rotor disks comprising a magnetic material, each of the rotor disks comprising a plurality of magnetic poles, the magnetic poles being spaced apart circumferentially, the rotor disks being coupled to the shaft for rotation about the shaft and generation of a rotating permeance wave; and

a stator assembly comprising a magnetic core stator disposed between the rotor disks, a plurality of armature windings supported on the magnetic core stator, and a stationary superconducting field coil disposed between the magnetic core stator and the shaft,

wherein the stationary superconducting field coil is configured as a stationary magneto-motive force (MMF) source for the rotating permeance wave produced by the rotor assembly to produce a rotating magnetic field.

12. The machine of claim 11 , wherein the rotating magnetic field is characterized by a flux loop that extends along the shaft, along the rotor disks and across the magnetic stator to supply a time varying magnetic flux to the armature windings.

13. The machine of claim 12 , wherein the magnetic poles are separated by air spaces.

14. The machine of claim 12 , wherein each of the rotor disks further comprises a non-magnetic material forming a plurality of non-magnetic regions separating the magnetic poles.

15. The machine of claim 11 , wherein the magnetic material employed in the shaft comprises an iron-cobalt alloy characterized by a saturation value of at least about 1.8 Tesla.

16. The machine of claim 11 , wherein the armature windings comprise superconducting armature windings.

17. The machine of claim 11 , wherein the armature windings are arranged to form a set of multiple phase windings.

18. The machine of claim 17 , wherein the magnetic stator defines a plurality of slots, and wherein the armature windings are arranged in the slots to form the multiple phase windings.

19. The machine of claim 11 , wherein the magnetic stator core comprises a plurality of laminations.

20. The machine of claim 11 , further comprising a plurality of rotor and stator assemblies arranged along the shaft.

21. A machine comprising:

a shaft adapted to rotate about a longitudinal axis of the shaft, the shaft comprising a non-magnetic material;

a rotor assembly rotationally engaged with the shaft, the rotor assembly comprising a pair of rotor disks comprising a magnetic material, each of the rotor disks comprising a plurality of magnetic poles, the magnetic poles being spaced apart circumferentially, the rotor disks being coupled to the shaft for rotation about the shaft and generation of a rotating permeance wave; and

a stator assembly comprising a plurality of armature windings disposed between the rotor disks and defining an air core stator, a stator yoke comprising a magnetic material, and a stationary superconducting field coil disposed between the air core stator and the stator yoke,

wherein the stationary superconducting field coil is configured as a stationary magneto-motive force (MMF) source for the rotating permeance wave produced by the rotor assembly to produce a rotating magnetic field.

22. The machine of claim 21 , wherein the rotating magnetic field is characterized by a flux loop that extends along the stator yoke, along the rotor disks and across the air core stator to supply a time varying magnetic flux to the armature windings.

23. The machine of claim 21 , further comprising a plurality of rotor and stator assemblies arranged along the shaft.

24. A machine comprising:

a shaft adapted to rotate about a longitudinal axis of the shaft, the shaft comprising a non-magnetic material;

a rotor assembly rotationally engaged with the shaft, the rotor assembly comprising a pair of rotor disks comprising a magnetic material, each of the rotor disks comprising a plurality of magnetic poles, the magnetic poles being spaced apart circumferentially, the rotor disks being coupled to the shaft for rotation about the shaft and generation of a rotating permeance wave; and

a stator assembly comprising a magnetic core stator disposed between the rotor disks, a plurality of armature windings supported on the magnetic core stator, a stator yoke comprising a magnetic material, and a stationary superconducting field coil disposed between the magnetic core stator and the stator yoke,

wherein the stationary superconducting field coil is configured as a stationary magneto-motive force (MMF) source for the rotating permeance wave produced by the rotor assembly to produce a rotating magnetic field.

25. The machine of claim 24 , wherein the rotating magnetic field is characterized by a flux loop that extends along the stator yoke, along the rotor disks and across the magnetic core stator to supply a time varying magnetic flux to the armature windings.

26. The machine of claim 24 , further comprising a plurality of rotor and stator assemblies arranged along the shaft.