Siemens SINAMICS S120 Function Manual page 174

Servo control
5.18 Dynamic Servo Control (DSC)
Operating states
The following operating states are possible for DSC (for details, see function diagram 3090 in
the SINAMICS S120/S150 List Manual):
Operating state for DSC
Speed/torque precontrol with linear
interpolation
Speed precontrol with splines
Speed/torque precontrol with splines
The following improvements are achieved as a result of spline interpolation:
1)
● A finer interpolation of the torque in the speed controller cycle and therefore softer motion; torque surges are
also avoided
● An extremely high path accuracy (i.e. lower following error in the control behavior) for torque-speed
feedforward control
● High-frequency path motions
For active balancing (T_SYMM > 0), using p1427 you can set an additive symmetrizing time constant
2)
T_SYMM_ADD to symmetrize the speed precontrol value when torque precontrol is active. In this case, the
speed precontrol value is symmetrized with the sum of the following time constants: T_SYMM
(p1195) + T_SYMM_ADD (p1427) + 0.5 · T_speed controller cycle (p0115[1]). In this case, speed generation
is automatically taken into account using position differences with half a speed controller cycle.
Activate DSC
If the preconditions for DSC 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.
Note
Position controller gain 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.
172
Meaning
As a result of the step-like torque precontrol in the position con‐
troller cycle, a pulsed torque characteristic is obtained with the
excitation cycle.
● The position setpoint is made symmetrical.
1)
● The speed precontrol value is not made symmetrical.
● The position setpoint is made symmetrical.
1)
● The speed precontrol value is made symmetrical.
● The torque precontrol value is not made symmetrical.
Function Manual, 06/2019, 6SL3097-5AB00-0BP2
2)
Drive functions