Siemens SINAMICS S120 Function Manual page 175

Channel p1155 for speed setpoint 1 and channel r1119 for the extended setpoint are
disconnected when DSC is active. p1160 for speed setpoint 2 and p1430 for the speed
precontrol are added to the speed setpoint from the DSC (see function diagram 3090).
Deactivating the DSC
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 precontrol.
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.
External encoder systems (except motor encoder)
If, with DSC active, an external encoder is to be used, this requires the selection of a telegram
with additional actual encoder values: Telegrams 6,106,116,118, 126, 136, 138, 146, 148, 166
or free telegrams.
For optimum control in the DSC mode, the same encoder(s) (encoder 2 and/or encoder 3) must
be selected for the control (master) and the drive via parameter p1192 "DSC encoder
selection".
If the encoder for the position actual value generation in the control and the encoder selected
for DSC differ regarding their pulse numbers and/or fine resolution, then this must be taken into
account in p1193. The factor represents the ratio of the pulse difference between the encoders
used for the same distance reference. Further, it should be noted that for different encoders
there are no dead times regarding their position actual value sensing (for example as is the
case for EnDat encoders and SSI encoders), as this will otherwise lead to undesirable behavior.
The effect of the parameters p1192 and p1193 is illustrated in function diagram 3090.
Wind-up effect
If the drive reaches its torque limits when in the DSC mode, e.g. because of excessively fast
setpoint inputs, then positioning motion can be overshot. With this so-called wind-up effect, the
drive overshoots the specified target, the controller enters a specific correction, the drive
reverses, overshoots the target again, etc. In order to avoid this behavior, the drive limits the
position controller to values that the drive can always reliably maintain depending on the
acceleration capability. Set p1400.17 = 1 to activate dynamic setpoint limiting in the DSC mode.
In this case, the total weight (m
p0341, p0342 and p1498 possibly using the mot ID). If the limiting responds, then this is
indicated in r1407.19. On this topic, also observe the description of parameter p1400.17 and
function diagram 3090.
Drive functions
Function Manual, 06/2019, 6SL3097-5AB00-0BP2
) must be precisely parameterized (determine the weight
tot
Servo control
5.18 Dynamic Servo Control (DSC)
173