Single phase switched reluctance machine with short flux path

1. A reluctance machine, comprising:

a stator having N stator poles, each stator pole having a stator winding; and

a rotor having N rotor poles and configured to rotate about an axis of rotation;

wherein the windings of the N stator poles are configured for excitation in a single phase; and

wherein current in the windings for two circumferentially adjacent stator poles is controlled such that axial current flow in the windings through a gap between the two circumferentially adjacent stator poles during single phase excitation flows in a same axial direction.

2. The machine of claim 1 , wherein the stator and rotor support a flux path traveling in a plane perpendicular to the axis of rotation that crosses two air gaps provided at corresponding pairs of rotor-stator poles that are circumferentially adjacent to each other.

3. The machine of claim 1 , wherein the stator is formed of a plurality of laminations extending in a direction perpendicular to the axis of rotation and wherein the rotor is formed of a plurality of laminations extending in a direction perpendicular to the axis of rotation.

4. The machine of claim 1 , wherein the stator is formed of a plurality of laminations extending in a direction perpendicular to the axis of rotation and wherein each pair of rotor poles for each circumferentially adjacent pair of rotor-stator poles is formed of a separate plurality of laminations extending in a direction perpendicular to the axis of rotation.

5. The machine of claim 1 , wherein N is an even integer greater than or equal to 4.

6. The machine of claim 1 , wherein the controlled current flow in the windings through the gap in the same axial direction is enforced by orientation of the windings on the adjacent stator poles carrying current during single phase excitation.

7. The machine of claim 1 , wherein the controlled current flow in the windings through the gap in the same axial direction is enforced by controlling a switched direction of current applied to the windings on the adjacent stator poles during single phase excitation.

8. The machine of claim 2 , wherein the rotor is configured to constrain the flux path to preclude radial flux propagation across the rotor to a diagonally opposite rotor pole.

9. The machine of claim 2 , wherein rotor is configured to constrain the flux path solely to the two adjacent rotor poles corresponding to the two air gaps.

10. The machine of claim 1 , wherein the rotor comprises a rotor ring and the plurality of rotor poles extend from said rotor ring.

11. The machine of claim 1 , wherein the rotor is configured inside of the stator.

12. The machine of claim 1 , wherein the stator is configured inside of the rotor.

13. The machine of claim 1 , wherein the stator and rotor support N/2 separate flux paths, each of said separate flux paths traveling in a plane perpendicular to the axis of rotation and crossing only two air gaps provided at corresponding pairs of rotor-stator poles that are circumferentially adjacent to each other.

14. The machine of claim 13 , wherein the rotor is configured to support separate flux path propagation only between circumferentially adjacent rotor poles.

15. The machine of claim 13 , wherein each separate flux path travels radially along a first stator pole, crosses a first air gap to a first rotor pole, travels radially along that first rotor pole, then travels circumferentially in the rotor to a second rotor pole circumferentially adjacent the first rotor pole, travels radially along the second rotor pole, crosses a second air gap to a second stator pole circumferentially adjacent the first stator pole, travels radially along the second stator pole, and then travels circumferentially in the stator back to said first stator pole.

16. A reluctance machine, comprising:

a first single phase reluctance machine;

a second single phase reluctance machine stacked on said first single phase reluctance machine but angularly offset from said first single phase reluctance machine;

wherein each of the first and second single phase reluctance machines comprises:

a stator having N stator poles, each stator pole having a stator winding; and

a rotor having N rotor poles and configured to rotate about an axis of rotation;

wherein the windings of the N stator poles are configured for excitation in a single phase; and

wherein current in windings for two circumferentially adjacent stator poles is controlled such that axial current flow in the windings through a gap between the two circumferentially adjacent stator poles during single phase excitation flows in a same axial direction; and

wherein the stator and rotor support N/2 separate flux paths, each of said separate flux paths traveling in a plane perpendicular to the axis of rotation and crossing only two air gaps provided at corresponding pairs of rotor-stator poles that are circumferentially adjacent to each other.

17. A reluctance machine, comprising:

a stator including a first stator pole and a circumferentially adjacent second stator pole;

a first stator winding for the first stator pole;

a second stator winding for the second stator pole;

wherein the first and second stator windings are electrically connected to be activated in a single phase;

a rotor including a first rotor pole and a circumferentially adjacent second rotor pole;

said stator and rotor supporting an isolated flux path that travels radially along the first stator pole, crosses a first air gap to the first rotor pole, travels radially along that first rotor pole, then travels circumferentially in the rotor to the second rotor pole, then travels radially along the second rotor pole, crosses a second air gap to the second stator pole, then travels radially along the second stator pole, and then travels circumferentially in the stator back to the first stator pole.