Siemens SINAMICS S120 Function Manual page 130

Servo control
4.8 Autotuning
Limitations:
● Because of the operating principle, the base adaptation algorithm can work reliably with
systems that have only one mechanical resonance frequency. Undesirable movements of
the adapted filter between the resonances can occur for systems with several mechanical
resonance frequencies.
● Because of the operating principle, inaccuracies can occur during the adaptation of the
blocking frequency. In such cases, the resonance frequency is only partly suppressed.
This is particularly the case for encoders with poor resolution (e.g. resolvers). These
inaccuracies can be reduced by increasing the actual speed value smoothing time
constant in parameter p1441.
● Stepped setpoint changes of the speed or velocity can cause unwanted movements of
the adaptive current setpoint filter.
● If in addition to a variable mechanical resonance frequency, the system also contains
non-variable mechanical resonance frequencies, the non-variable frequencies must be
suppressed with fixed current setpoint filters. The adapted bandstop filter should be the
last filter in the filter cascade of the bandstop filters. Otherwise the adaptation may be
subject to interference from non-variable resonance frequencies, which may cause
unwanted movements of the blocking frequency.
Figure 4-12 Example: Current setpoint filter 5 is the last filter used in the cascade
Internal activation threshold
The internal activation threshold can be weighted via parameter p5284:
● If the adaptation reacts too sensitively to other disturbances such as jumps in the speed
or load torque, the activation threshold should be set high.
● If the adaptation is too insensitive and resonance frequencies do not occur despite strong
excitation, the activation threshold can be reduced.
Range of movement of the adapted filter
The range of movement of the adapted filter can be limited with parameter p5282 or p5283.
130
Function Manual, 11/2017, 6SL3097-4AB00-0BP5
Drive functions