Siemens SINAMICS S120 Function Manual page 84

Operating Modes
Servo control
General low-pass with reduction
Table 3-6 Example of general low-pass with reduction
STARTER filter parameters
Characteristic frequency f
500 Hz
Damping D = 0.7
Reduction Abs = --10 dB
Conversion to parameters for general order filters
S Numerator frequency f
S Numerator damping f
S Denominator frequency f
S Denominator damping D
Transfer function general 2nd-order filter

s
2πf Z
H
=
(s)

s
2πf N
s = jω = j ⋅ 2πf
S Numerator frequency f
S Numerator damping D
S Denominator frequency f
S Denominator damping D
Table 3-7 Example of general 2nd-order filter
STARTER filter parameters
Numerator frequency f = 500 Hz
Z
Numerator damping D = 0.02 dB
Z
Denominator frequency f
900 Hz
Denominator damping D
N
0.15 dB
3-84
Amplitude log frequency curve
=
Abs
= f
Z Abs
f
Abs
=
Z
Abs
10
40
N
N
2

2D Z
⋅ s + 1
+
2πf Z
2

2D N
⋅ s + 1
+
2πf N
Z
Z
N
N
Amplitude log frequency curve
=
N
=
Phase frequency curve
(start of reduction)
Phase frequency curve
© Siemens AG, 2005. All rights reserved
SINAMICS S120 Function Manual, 06/05 Edition