Siemens Sinamics S120 Function Manual page 122

Servo control
3.15 Dynamic Servo Control (DSC)
Activation
If the preconditions for dynamic servo control are fulfilled, then the DSC structure is activated
using a logical interconnection of the following parameters via a selected PROFIdrive
telegram:
● p1190 "DSC position deviation XERR"
● p1191 "DSC position controller gain KPC"
● p1194 "CI: DSC control word DSC_STW"
● p1195 "CI: DSC Symmetrizing time constant T_SYMM"
● p1430 "CI: Speed precontrol"
If KPC = 0 is transferred, only speed control with the speed precontrol values can be used
(p1430, PROFIdrive N_SOLL_B and p1160 n_set_2). Position controlled operation requires a
transfer of KPC > 0.
When dynamic servo control is activated, you check the position controller gain KPC in the
master. It may be necessary to correct the setting.
Note
KPC when DSC is activated
After activating dynamic servo control, check the position controller gain KPC in the master.
It may be necessary to correct the setting.
Channel p1155 for speed setpoint 1, as well as channel r1119 for the extended setpoint, are
disconnected when DSC is active.
When DSC is activated, p1160 for speed setpoint 2 and p1430 for the speed precontrol are
added to the speed setpoint from the DSC, see function diagram 5030.
Deactivation
If the interconnection is removed at the connector input for KPC or XERR (p1191 = 0 or
p1190 = 0), the DSC structure is dissolved and the "DSC" function" deactivated. The sum
from r1119 and p1155 is then added to the values from p1160 and p1430 from the speed
pre-control.
Since it is possible to set higher gain factors using DSC, the control loop can become
unstable when DSC is disabled. For this reason, before deselecting DSC, the value for KPC
in the master must be reduced.
Speed setpoint filter
A speed setpoint filter for smoothing the speed setpoint steps is not required when DSC is
active.
When using the "DSC" function, it only makes sense to use speed setpoint filter 1 to support
the position controller, e.g. to suppress resonance effects.
120
Function Manual, (FH1), 01/2012, 6SL3097-4AB00-0BP2
Drive functions