System for controlling a magnetically levitated rotor

• US 7,023,118 B1
• Filed: 03/12/2003
• Issued: 04/04/2006
• Est. Priority Date: 03/14/2002
• Status: Active Grant

• Current Assignee: National Aeronautics and Space Administration US Government As Represented By The Administrator of The
• Original Assignee: United States Administrator of National Aeronautics and Space Administration
• Inventors: Morrison, Carlos R.
• Primary Examiner(s): Schuberg, Darren
• Assistant Examiner(s): MOHANDESI, IRAJ A
• Application Number:
  US10/390,256
• Time in Patent Office: 1,119 Days
• Field of Search: 310/90.05, 310/90.5, 310/74
• US Class Current: 310/90.5
• CPC Class Codes: F16C 32/0442 with devices affected by abnormal, undesired or non-standard conditions such as shock-load, power outage, start-up or touchdown
• CPC Class Codes: F16C 32/0455 including digital signal processing [DSP] and analog/digital conversion [A/D, D/A]
• CPC Class Codes: F16C 32/0489 with active support of five degrees of freedom, e.g. two radial magnetic bearings combined with an axial bearing

Abstract

In a rotor assembly having a rotor supported for rotation by magnetic bearings, a processor controlled by software or firmware controls the generation of force vectors that position the rotor relative to its bearings in a “bounce” mode in which the rotor axis is displaced from the principal axis defined between the bearings and a “tilt” mode in which the rotor axis is tilted or inclined relative to the principal axis. Waveform driven perturbations are introduced to generate force vectors that excite the rotor in either the “bounce” or “tilt” modes.

Claims

1. A system for controlling the alignment of a rotor magnetically supportable in magnetic bearings, comprising:

a rotor assembly having a rotor supportable for rotation by at least first and second magnetic bearings, the rotor having a longitudinal axis and said first and second magnetic bearings defining a principal axis therebetweeen, each of said first and second magnetic bearings having magnetic poles with respective magnet coils associated therewith, a voltage and/or current flow through the respective magnet coils magnetically supporting the rotor for rotation relative to said first and second magnetic bearings and selectively applying force vectors to the rotor to selectively position the longitudinal axis relative to the principal axis;

a processor means connected to the respective magnet coils for executing instructions to control the voltage and/or current to the respective magnet coils to apply force vectors to the rotor, said processor means providing a selected waveform to be impressed on the magnetic field of said first and second magnetic bearings to excite the rotor in response to the waveform, the waveform impressed on the rotor at a selected angle relative to a fixed reference coordinate system and remaining stationary in that coordinate system during periods of time when the rotor is in motion; and

instructions stored in or on a processor-readable media executable by the processor means for positioning the rotor such that the longitudinal axis thereof is not axially coincident with the principal axis.

2. The system of claim 1, wherein the longitudinal axis is off-set from the principal axis.

3. The system of claim 1, wherein the longitudinal axis is aligned non-parallel to the principal axis.

4. The system of claim 1, wherein the longitudinal axis is aligned non-parallel to the principal axis and defines a pivot point intermediate the ends of the rotor.

5. The system of claim 4, wherein the position of the pivot point along the longitudinal axis is determined as a function of the ratio of the force vectors applied by the first magnetic bearing and the second magnetic bearing.

6. The system of claim 1, wherein the waveform is selected from the group comprising sine waveform, sine squared waveform, cosine waveform, cosine squared waveform, random waveform, square waveform, squared pulse waveform, triangular waveform, single square waveform, single triangular waveform, sawtooth waveform.

7. A system for controlling the alignment of a rotor magnetically supportable in magnetic bearings, comprising:

a rotor assembly having a rotor supportable for rotation by at least first and second magnetic bearings, the rotor having a longitudinal axis and said first and second magnetic bearings defining a principal axis therebetweeen, each of said first and second magnetic bearings having magnetic poles with respective magnet coils associated therewith, a voltage and/or current flow through the respective magnet coils magnetically supporting the rotor for rotation relative to said first and second magnetic bearings and selectively applying force vectors to the rotor to selectively position the longitudinal axis relative to the principal axis;

a processor means connected to the respective magnet coils for executing instructions to control the voltage and/or current to the respective magnet coils to apply force vectors to the rotor, said processor means providing a selected waveform to be impressed on the magnetic field of said first and second magnetic bearings to excite the rotor in response to the waveform, the waveform impressed on the rotor at a selected angle relative to a fixed reference coordinate system and rotating with the rotor when the rotor is in motion; and

instructions stored in or on a processor-readable media executable by the processor means for positioning the rotor such that the longitudinal axis thereof is not axially coincident with the principal axis.

8. The system of claim 7, wherein the waveform perturbation rotates in synchronism with the rotor when the rotor is in motion.

9. The system of claim 7, wherein the longitudinal axis is off-set from the principal axis.

10. The system of claim 7, wherein the longitudinal axis is aligned non-parallel to the principal axis.

11. The system of claim 7, wherein the longitudinal axis is aligned non-parallel to the principal axis and defines a pivot point intermediate the ends of the rotor.

12. The system of claim 7, wherein the position of the pivot point along the longitudinal axis is determined as a function of the ratio of the force vectors applied by the first magnetic bearing and the second magnetic bearing.

13. The system of claim 7, wherein the waveform is selected from the group comprising sine waveform, sine squared waveform, cosine waveform, cosine squared waveform, random waveform, square waveform, squared pulse waveform, triangular waveform, single square waveform, single triangular waveform, sawtooth waveform.

14. A system for controlling the alignment of a rotor magnetically supportable in magnetic bearings, comprising:

a rotor assembly having a rotor supportable for rotation by at least first and second magnetic bearings, the rotor having a longitudinal axis and said first and second magnetic bearings defining a principal axis therebetweeen, each of said first and second magnetic bearings having magnetic poles with respective magnet coils associated therewith, a voltage and/or current flow through the respective magnet coils magnetically supporting the rotor for rotation relative to said first and second magnetic bearings and selectively applying force vectors to the rotor to selectively position the longitudinal axis relative to the principal axis;

a processor means connected to the respective magnet coils for executing instructions to control the voltage and/or current to the respective magnet coils to apply force vectors to the rotor, said processor means providing a selected waveform to be impressed on the magnetic field of said first and second magnetic bearings to excite the rotor in response to the waveform; and

instructions stored in or on a processor-readable media executable by the processor means for positioning the rotor such that the longitudinal axis thereof is not axially coincident with the principal axis;

wherein the waveform is selected from the group comprising sine waveform, sine squared waveform, cosine waveform, cosine squared waveform, random waveform, square waveform, squared pulse waveform, triangular waveform, single square waveform, single triangular waveform, sawtooth waveform.

15. The system of claim 14, wherein the longitudinal axis is off-set from the principal axis.

16. The system of claim 14, wherein the longitudinal axis is aligned non-parallel to the principal axis.

17. The system of claim 14, wherein the longitudinal axis is aligned non-parallel to the principal axis and defines a pivot point intermediate the ends of the rotor.

18. The system of claim 15, wherein the position of the pivot point along the longitudinal axis is determined as a function of the ratio of the force vectors applied by the first magnetic bearing and the second magnetic bearing.