Siemens SINAMICS S120 Function Manual page 86

Operating Modes
Servo control
Low-pass 2nd order (PT2 filter)
Transfer function:
+
H
(s)
s
2pf
Denominator natural frequency f
Denominator damping D
Table 3-2 Example of a PT2 filter
STARTER filter parameters
Characteristic frequency f
500 Hz
Damping D 0.7 dB
N
Band-stop with infinite notch depth
Table 3-3 Example of band-stop with infinite notch depth
STARTER filter parameters
f
Blocking frequency = 500 Hz
Sp
(–3dB) f
Bandwidth = 500 Hz
BB
K
Notch depth = –R dB
Abs
Reduction = 0 dB
Simplified conversion to parameters for general order filters:
Reduction or increase after the blocking frequency (Abs)
Infinite notch depth at the blocking frequency
S Numerator frequency f
S Numerator damping D
S Denominator natural frequency f
S Denominator damping D
3-86
1
2
2D N
) @ s ) 1
2pf
N N
N
N
Amplitude log frequency curve
N
Amplitude log frequency curve
= f
Z Sp
= 0
Z
+
2 @ f
N
Phase frequency curve
Phase frequency curve
= f
N Sp
f
BB
Sp
© Siemens AG 2006 All Rights Reserved
SINAMICS S120 Function Manual, 03/2006 Edition