![](bg6.png)
compensation. For y
1,
the standard deviations of the
air-gap with compensation and without
compensation were calculated to be
m
53.14=
and
m
43.1
, respectively. For y
2,
the standard deviations
of the air-gap with compensation and without
compensation were calculated to be
m
13.13=
and
m
08.1
, respectively. The control voltages were
slightly reduced after employing compensation.
Figure 10 shows the spectra of the air-gap responses
in Fig. 9. The disturbance attenuation ratio is
approximately–20db within the frequency band of
the base motion.
Figure 8: Measured and fitted FRF of
11
ˆ
W
Figure 9: Air-gap responses w/ and w/o compensation
20 40 60 80 100
10
-3
10
-2
Compensated
Uncompensated
Spectrum of y
1
Frequency [Hz]
20 40 60 80 100
10
-3
10
-2
Uncompensated
Compensated
Spectrum of y
2
Frequency [Hz]
Figure 10: Spectra of air-gap with and without
compensation
5 CONCLUSION
In this work, an experimental feedforward
compensator design technique, developed from an
adaptive estimation by means of the Multiple
Filtered-x least mean square (MFXLMS) algorithm
has been proposed. The feasibility of the proposed
technique has been verified by an experimental
study, by using a 2-DOF active magnetic bearing
system subject to base motion. The experimental
results showed that the standard deviation of the
compensated response was reduced to less than 10%
of that by feedback control alone.
ACKNOWLEDGEMENT
This work was supported by grant no.( R01-2003-
000-10857-0) from the Basic Research Program of
the Korea Science & Engineering Foundation.
10 15 20 25 30 35 40 45 50 55
-160
-150
-140
measured
fitted
Phase angle [degree]
Frequency [Hz]
10 15 20 25 30 35 40 45 50 55
0.45
0.50
0.55
0.60
0.65
0.70
0.75
measured
fitted
Magnitude
Frequency [Hz]
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A DISTURBANCE COMPENSATION CONTROL FOR AN ACTIVE MAGNETIC BEARING SYSTEM BY A
MULTIPLE FXLMS ALGORITHM
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