Siemens SINAMICS S120, Function Manual

Page: 514 / 1094

Function modules
8.8 Basic positioner
Drive functions
514
Function Manual, 11/2017, 6SL3097-4AB00-0BP5
Jerk limitation
Acceleration and deceleration can change suddenly if jerk limiting has not been activated.
The diagram below shows the traversing profile when jerk limitation has not been activated.
The maximum acceleration (a
max
) and deceleration (d
max
) are effective immediately. The
drive accelerates until the target speed (v
target
) is reached and then switches to the constant
velocity phase.
Figure 8-15 Without jerk limitation
Jerk limitation can be used to achieve a ramp-like change of both variables, which ensures
"smooth" acceleration and braking as shown in the diagram below. Ideally, acceleration and
deceleration should be linear.
Figure 8-16 Activated jerk limitation
The maximum gradient (r
k
) can be set in parameter p2574 (jerk limitation) in the unit LU/s
3
for both acceleration and braking. The resolution is 1000 LU/s
3
. To activate the limitation
permanently, set parameter p2575 (Activate jerk limitation) to 1. In this case, limitation
cannot be activated or deactivated in traversing block mode by means of the command
"JERK". Switching the limitation on/off in the traversing block mode requires parameter
p2575 (Activate jerk limitation) to be set to zero. The status signal r2684.6 (Jerk limitation
active) indicates whether or not jerk limitation is active.