Bearingless switched reluctance motor

• US 6,727,618 B1
• Filed: 06/10/2002
• Issued: 04/27/2004
• Est. Priority Date: 06/10/2002
• Status: Expired due to Fees

• Current Assignee: US Government As Represented By The Director National Security Agency
• Original Assignee: The United States of America As Represented By The Secretary of Agriculture
• Inventors: Morrison, Carlos R.
• Primary Examiner(s): Mullins, Burton S.
• Assistant Examiner(s): Scheuermann, David W.
• Application Number:
  US10/164,754
• Time in Patent Office: 687 Days
• Field of Search: 310/166, 310/168, 310/90.5, 310/261, 310/267, 310/268
• US Class Current: 310/90.5
• CPC Class Codes: F16C 32/0493 integrated in an electrodynamic machine, e.g. self-bearing motor
• CPC Class Codes: H02K 19/103 Motors having windings on the stator and a variable reluctance soft-iron rotor without windings
• CPC Class Codes: H02K 7/09 with magnetic bearings

Abstract

A switched reluctance motor has a stator with a first set of poles directed toward levitating a rotor horizontally within the stator. A disc shaped portion of a hybrid rotor is affected by the change in flux relative to the current provided at these levitation poles. A processor senses the position of the rotor and changes the flux to move the rotor toward center of the stator. A second set of poles of the stator are utilized to impart torque upon a second portion of the rotor. These second set of poles are driven in a traditional switched reluctance manner by the processor.

Claims

1. A bearingless switched reluctance machine comprising:

a stator having a plurality of inwardly directed protruding poles, four of the plurality of poles being levitation poles dedicated for use as a magnetic bearing, the remaining poles utilized as torque generating poles; and

a rotor having a first portion with a plurality of outwardly directed poles.

2. The bearingless switched reluctance machine of claim 1 wherein the levitation poles are located at the twelve o'"'"'clock, three o'"'"'clock, six o'"'"'clock, and nine o'"'"'clock positions relative to one another about the stator.

3. The bearingless switched reluctance machine of claim 1 wherein the rotor is a hybrid rotor further comprising a second disc shaped portion.

4. The bearingless switched reluctance machine of claim 3 wherein the first portion of the rotor is scalloped shaped and the second disc shaped portion is stacked relative to the first portion to form the hybrid rotor.

5. The bearingless switched reluctance machine of claim 4 wherein the machine is a motor.

6. The bearingless switched reluctance machine of claim 4 wherein the stator has a length which is at least approximately as long as the stacked first and second portions of the hybrid rotor.

7. The bearingless switched reluctance machine of claim 1 further comprising at least two sensors detecting the position of the rotor within the stator.

8. A switched reluctance motor comprising:

a stator having a plurality of pairs of pole portions that extend substantially in the direction of an axis of the stator and project radially inward in such a manner that each pair of pole portions are located opposite each other and define a bore therein;

a rotor rotatably disposed within the bore of the stator, the rotor having a first portion with a plurality of pairs of projected poles that extend substantially in the direction of an axis of the rotor and that are projected radially outward so that the projected poles may face the pole portions of the stator while maintaining a clearance therefrom; and

a plurality of coils wound around the plurality of pairs of the pole portions of the stator, a first set of the plurality of coils utilized exclusively to control a horizontal position of the axis of the rotor relative to the axis of the stator, and a second set of the plurality of coils utilized to impart torque to rotate the stator, wherein the first and second set of the plurality of coils are not located on a single pole portion.

9. The switched reluctance motor of claim 8 wherein the first set of coils are oriented on two pairs of stator poles.

10. The switched reluctance motor of claim 9 wherein the two pairs of stator poles are ninety degrees apart.

11. The switched reluctance motor of claim 8 further comprising at least two sensors sensing the position of the rotor within the stator.

12. The switched reluctance motor of claim 11 further comprising a processor in communication with the at least two sensors receiving signals therefrom.

13. The switched reluctance motor of claim 12 wherein the processor is adapted to provide control signals to at least some of the first set of the plurality of coils to move the rotor axis towards the stator axis.

14. The switched reluctance motor of claim 13 wherein the control signal, the processor, and the signal from the at least two sensors comprise a closed loop.

15. The switched reluctance motor of claim 12 wherein the processor provides a bias current to the levitation poles.

16. The switched reluctance motor of claim 11 wherein at least one sensor further comprises a first and a second sensor oriented at ninety degrees relative to one another.

17. The switched reluctance motor of claim 11 wherein the at least one sensor is a magnetic sensor and located external to the stator.

18. The switched reluctance motor of claim 8 wherein the rotor further comprises a second disc shaped portion.

19. The switched reluctance motor of claim 17 wherein the disc substantially fills the bore while maintaining a clearance from the stator poles.

20. A switched reluctance motor comprising:

a stator having a plurality of poles portions that project inwardly toward a bore in a direction of an axis of the stator; and

a hybrid rotor located in the bore having a first portion with projected poles extending substantially in the direction of an axis of the rotor with spaces in between adjacent poles, the first portion maintaining a clearance from the stator poles, and a second portion having a disc shape connected to the first portion, the second portion having a circumference extending radially outwardly at least as far as a portion of the spaces.