Software for system for controlling a magnetically levitated rotor

• US 6,809,450 B1
• Filed: 12/04/2003
• Issued: 10/26/2004
• Est. Priority Date: 03/14/2002
• Status: Expired due to Fees

• Current Assignee: United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration
• Original Assignee: United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration
• Inventors: Morrison, Carlos R.
• Primary Examiner(s): Le, Dang
• Assistant Examiner(s): Mohandesi, Iraj A.
• Application Number:
  US10/729,580
• Time in Patent Office: 327 Days
• Field of Search: 310/90.5, 310/95.5, 310/90, 310/91, 700/174, 700/42, 700/45, 700/44, 318/806, 318/574, 318/575
• 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. Software stored in or on a computer-readable medium for causing a software-controlled processing device coupled to first and second magnetic bearings supporting a rotor to control positioning of the rotor in the first and second magnetic bearings, the rotor having a longitudinal axis and the first and second magnetic bearings defining a principal axis therebetween, each of the first and second magnetic bearings having at least four magnetic poles with respective magnet coils associated therewith, the voltage and/or current flow through the magnet coils generating magnetic field force vectors to support the rotor for rotation relative to the first and second magnetic bearings, the force vectors under the control of the processor to selectively position the longitudinal axis relative to the principal axis, the software causing the processing device to perform the function of:

controlling the force vectors to align the rotor in the first and second magnetic bearings so that the longitudinal axis thereof and the principal axis defined between the first and second magnetic bearings are not axially coincident with one another; and

providing a selected waveform to be impressed on the magnetic field of the first and second magnetic bearings to excite the rotor in response to the selected 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.

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

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

4. The software 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 software 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 software 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. Software stored in or on a computer-readable medium for causing a software-controlled processing device coupled to first and second magnetic bearings supporting a rotor to control positioning of the rotor in the first and second magnetic bearings, the rotor having a longitudinal axis and the first and second magnetic bearings defining a principal axis therebetween, each of the first and second magnetic bearings having at least four magnetic poles with respective magnet coils associated therewith, a voltage and/or current flow through the magnet coils generating magnetic field force vectors to support the rotor for rotation relative to the first and second magnetic bearings, the force vectors under the control of the processing device to selectively position the longitudinal axis relative to the principal axis, the software causing the processing device to perform the function of:

controlling the force vectors to align the rotor in the first and second magnetic bearings so that the longitudinal axis thereof and the principal axis defined between the first and second magnetic bearings are not axially coincident with one another; and

providing a selected waveform to be impressed on the magnetic field of the first and second magnetic bearings to excite the rotor in response to the selected waveform, the waveform impressed on the rotor at a selected angle relative to a fixed reference coordinate and rotating with the rotor when the rotor is in motion.

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

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

10. The software 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.

11. The software of claim 10, 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.

12. The software of claim 7, wherein the waveform rotates in synchronism with the rotor when the rotor is in motion.

13. The software 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. Software stored in or on a computer-readable medium for causing a software-controlled processing device coupled to first and second magnetic bearings supporting a rotor to control positioning of the rotor in the first and second magnetic bearings, the rotor having a longitudinal axis and the first and second magnetic bearings defining a principal axis therebetween, each of the first and second magnetic bearings having at least four magnetic poles with respective magnet coils associated therewith, a voltage and/or current flow through the magnet coils generating magnetic field force vectors to support the rotor for rotation relative to the first and second magnetic bearings, the force vectors under the control of the processing device to selectively position the longitudinal axis relative to the principal axis, the software causing the processing device to perform the function of:

controlling the force vectors to align the rotor in the first and second magnetic bearings so that the longitudinal axis thereof and the principal axis defined between the first and second magnetic bearings are not axially coincident with one another; and

providing a selected waveform to be impressed on the magnetic field of the first and second magnetic bearings to excite the rotor in response to the selected waveform, the waveform 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 software of claim 14, wherein the longitudinal axis is off-set from the principal axis.

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

17. The software 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 software of claim 17, 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 bearing and the second bearing.