Electrical machine rotors

1. A rotor for an electrical machine, the rotor comprising:

a hollow non-magnetic shaft extending along an axis and having an exterior surface, wherein the exterior surface of the shaft defines a shaft space extending along the axis;

an active region, wherein at least a portion of the active region is disposed within the shaft space, wherein the active region is an electromagnetically active region comprising a plurality of permanent magnets; and

a plurality of coolant passages extending within the active region.

2. The rotor of claim 1 , wherein the hollow non-magnetic shaft comprises a fiber-reinforced composite material.

3. The rotor of claim 1 , wherein the active region is substantially completely radially disposed within the shaft space.

4. The rotor of claim 1 , wherein at least some of the coolant passages extend substantially adjacent to at least a portion of at least one of the permanent magnets.

5. The rotor of claim 1 , wherein the active region is a substantially annular structure arranged around the axis and having a central opening extending therethrough along the axis.

6. The rotor of claim 1 , wherein the active region is configured to permit substantially axial coolant flow within the shaft space.

7. A rotor for an electrical machine, the rotor comprising:

a hollow non-magnetic shaft extending along an axis and having an exterior surface, wherein the exterior surface of the shaft defines a shaft space extending along-the axis;

an active region, wherein at least a portion of the active region is disposed within the shaft space; and

a plurality of coolant passages extending within the active region, wherein the active region is configured to permit substantially axial coolant flow within the shaft space and at least some of the coolant passages are configured to permit substantially radial coolant flow within the active region within the shaft space.

8. The rotor of claim 6 , wherein at least some of the coolant passages are configured to permit substantially axial coolant flow within the active region within the shaft space.

9. A rotor for an electrical machine, the rotor comprising:

a hollow non-magnetic shaft extending along an axis and having an exterior surface, wherein the exterior surface of the shaft defines a shaft space extending along the axis;

an active region, wherein at least a portion of the active region is disposed within the shaft space; and

a plurality of coolant passages extending within the active region, wherein the active region includes higher flux density portions and reduced flux density portions, the reduced flux density portions have a lower magnetic flux density than the higher flux density portions, and at least some of the passages extend through reduced flux density portions of the active region.

10. The rotor of claim 9 , wherein at least some of the passages extend through interpole portions of the active region.

11. A rotor for an electrical machine, the rotor comprising:

a hollow non-magnetic shaft extending along an axis and having an exterior surface, wherein the exterior surface of the shaft defines a shaft space extending along the axis;

an active region, wherein at least a portion of the active region is disposed within the shaft space; and

a plurality of coolant passages extending within the active region, wherein at least some of the passages extend parallel to the axis and have an elongated cross-section transverse to the axis, and the elongated cross-section is arranged approximately parallel to local magnetic flux lines.

12. A rotor for an electrical machine, the rotor comprising:

a hollow non-magnetic shaft extending along an axis and having an exterior surface, wherein the exterior surface of the shaft defines a shaft space extending along the axis;

an active region, wherein at least a portion of the active region is disposed within the shat space; and

a plurality of coolant passages extending within the active region, wherein the shaft includes a wall having an interior surface and the exterior surface with at least one opening extending through the wall from the interior surface to the exterior surface.

13. A rotor for an electrical machine the rotor comprising:

a hollow non-magnetic shaft extending along an axis and having an exterior surface, wherein the exterior surface of the shaft defines a shaft space extending along the axis;

an active region, wherein at least a portion of the active region is disposed within the shaft space; and

a plurality of coolant passages extending within the active region, further comprising a connection region disposed between the shaft and the active region, wherein the connection region is configured to secure the shaft relative to the active region and includes a plurality of openings extending radially therethrough.

14. The rotor of claim 13 , wherein the active region comprises a steel structure extending along the axis to an end, and the connection region is cast onto the active region and extends along the axis from the end.

15. The rotor of claim 1 incorporated into an electrical machine, the electrical machine comprising; the rotor; and

a stator.

16. The electrical machine of claim 15 , comprising a magnetic bearing configured to magnetically levitate the rotor relative to the stator.

17. The electrical machine of claim 15 , wherein the electrical machine is an inner rotor electrical machine.

18. The electrical machine of claim 15 , wherein the electrical machine is an outer rotor electrical machine.

19. An electrical machine, the electrical machine comprising:

a stator;

a rotor, the rotor comprising:

hollow non-magnetic shaft extending along an axis and having an exterior surface, wherein the exterior surface of the shaft defines a shaft space extending along the axis;

an active region, wherein at least a portion of the active region is disposed within the shaft space; and

a plurality of coolant passages extending within the active region, wherein the hollow non-magnetic shaft extends along the axis to an end; and

a bearing disposed proximate the end of the hollow non-magnetic shaft and configured to support the rotor for rotation relative to the stator.

20. The electrical machine of claim 16 , wherein the hollow non-magnetic shaft extends along the axis to an end, and the magnetic hearing is disposed proximate the end of the hollow non-magnetic shaft.

21. The electrical machine of claim 19 , wherein the hearing is magnetic and configured to magnetically levitate the rotor relative to the stator.