A novel method for transient rotor/active magnetic bearing control using sampled wavelet coefficients is proposed. Control currents are formulated in the wavelet transform domain, prior to signal reconstruction. The wavelet based controller is designed from target transient responses due to step changes in wavelet coefficients of applied forces. Transient system dynamics are embedded in the controller and evaluated from on-line system identification. Experimental validation is undertaken using a flexible rotor/active magnetic bearing system. Mass loss tests were performed at two critical speeds corresponding to near sudden changes in unbalance that are capable of exciting rotor dynamic modes in a transient manner. The controller is shown to suppress the transient responses within a finite settling time.

Issue Section:
Gas Turbines: Structures and Dynamics
Keywords:
rotors, machine control, vibration control, magnetic bearings, wavelet transforms, transient response, control system synthesis, signal reconstruction, machine bearings
Topics:
Magnetic bearings, Rotors, Transients (Dynamics), Wavelets, Control equipment
1.
Keogh
,
P. S.
,
Mu
,
C.
, and
Burrows
,
C. R.
, 1995, “
Optimised Design of Vibration Controllers for Steady State and Transient Excitation of Flexible Rotors
,”
Proc. Inst. Mech. Eng., Part C: J. Mech. Eng. Sci.
0954-4062
209
(
3
), pp.
155
–
168
.
Crossref
Search ADS
 
2.
Nonami
,
K.
, and
Ito
,
T.
, 1994, “
μ-Synthesis of Flexible Rotor Magnetic Bearing Systems
,”
Proc. of 4th International Symposium on Magnetic Bearings
, p.
73
–
78
.
3.
Burrows
,
C. R.
, and
Sahinkaya
,
M. N.
, 1983, “
Vibration Control of Multi-Mode Rotor-Bearing Systems
,”
Proceedings of the Royal Society, London
,
386
(
1790
), pp.
77
–
94
.
4.
Burrows
,
C. R.
,
Sahinkaya
,
M. N.
, and
Clements
,
S.
, 1989, “
Active Vibration Control of Flexible Rotors: An Experimental and Theoretical Study
,”
Proceedings of the Royal Society, London
,
422
(
1862
), pp.
123
–
146
.
5.
Knospe
,
C. R.
,
Hope
,
R. W.
,
Fedigan
,
S. J.
, and
Williams
,
R. D.
, 1995, “
Experiments in the Control of Unbalance Response Using Magnetic Bearings
,”
Mechatronics
0957-4158,
5
(
4
), pp.
385
–
400
.
Crossref
Search ADS
 
6.
Knospe
,
C. R.
,
Fedigan
,
S. J.
,
Hope
,
R. W.
, and
Williams
,
R. D.
, 1997, “
A Multitasking DSP Implementation of Adaptive Magnetic Bearing Control
,”
IEEE Trans. Control Syst. Technol.
1063-6536,
5
(
2
), pp.
230
–
238
.
Crossref
Search ADS
 
7.
Knospe
,
C. R.
,
Tamer
,
S. M.
, and
Lindlau
,
J.
, 1997, “
New Results in Adaptive Vibration Control
,”
Proc., 1997 Industrial Conference and Exhibition on Magnetic Bearings
, pp.
209
–
219
.
8.
Shafai
,
B.
,
Beale
,
S.
,
LaRocca
,
P.
, and
Cussons
,
E.
, 1994, “
Magnetic Bearing Control Systems and Adaptive Forced Balancing
,”
IEEE Control Syst. Mag.
0272-1708,
14
(
2
), pp.
4
–
13
.
9.
Zimmerman
,
D. C.
,
Inman
,
D. J.
, and
Juang
,
J. N.
, 1991, “
Vibration Suppression Using a Constrained Rate-Feedback-Threshold Strategy
,”
ASME J. Vibr. Acoust.
0739-3717,
113
(
3
), pp.
345
–
353
.
Crossref
Search ADS
 
10.
Cole
,
M. O. T.
,
Keogh
,
P. S.
, and
Burrows
,
C. R.
, 2002, “
Control of Multifrequency Rotor Vibration Components
,”
Proc. Inst. Mech. Eng., Part C: J. Mech. Eng. Sci.
0954-4062,
216
(
2
), pp.
165
–
177
.
Crossref
Search ADS
 
11.
Keogh
,
P. S.
,
Cole
,
M. O. T.
, and
Burrows
,
C. R.
, 2002, “
Multi-State Transient Rotor Vibration Control Using Sampled Harmonics
,”
ASME J. Vibr. Acoust.
0739-3717,
124
(
2
), pp.
186
–
197
.
Crossref
Search ADS
 
12.
Chancey
,
V. C.
, and
Flowers
,
G. T.
, 2001, “
Identification of Transient Vibration Characteristics Using Absolute Harmonic Wavelet Coefficients
,”
J. Vib. Control
1077-5463,
7
(
8
), pp.
1175
–
1193
.
Crossref
Search ADS
 
13.
Newland
,
D. E.
, 1994, “
Wavelet Analysis of Vibration, Part 1: Theory
,”
ASME J. Vibr. Acoust.
0739-3717,
116
(
4
), pp.
409
–
416
.
Crossref
Search ADS
 
14.
Newland
,
D. E.
, 1994, “
Wavelet Analysis of Vibration, Part 2: Wavelet Maps
,”
ASME J. Vibr. Acoust.
0739-3717,
116
(
4
), pp.
417
–
425
.
Crossref
Search ADS
 
15.
Strang
,
G.
, and
Nguyen
,
T.
, 1996,
Wavelets and Filter Banks
,
Wellsey-Cambridge Press
.
16.
Vetterli
,
M.
, and
Kovačević
, 1995,
Wavelets and Subband Coding
,
Prentice-Hall
,
Englewood Cliffs, NJ
.
Copyright © 2007
 by American Society of Mechanical Engineers
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