Siemens SINAMICS S120 Function Manual page 119

Adapted controller parameters
As soon as the "Online tuning" is active, the controller parameters are adapted to the
estimated moment of inertia. However, the controller parameters are only recalculated when
the moment of inertia has changed more than 5% compared to the last calculation.
Otherwise the controller settings are not changed.
All adaptive controller settings also depend on the moment of inertia, e.g. determined by the
estimator. If p5271.2 = 1 is set, the Kp factor depends directly on this moment of inertia.
All other variables are only indirectly dependent on the moment of inertia.
Kp (speed controller gain)
The speed controller gain is set proportional to the motor moment of inertia. The gains are
proportional to the dynamic response factor p5272. An adaptation of the Kp factor depending
on the estimated moment of inertia is only performed when p5271.2 is set.
Parameter p5273 is used to set how many percent of the estimated load moment of inertia is
to be taken into account as effective moment of inertia for the calculation of the Kp factor.
With 0%, only the motor moment of inertia is effective, with 100%, the total moment of inertia
is used for the calculation of the Kp factor.
When calculating the speed controller gain, the time constants of the parameterized current
setpoint or actual speed value filter are also taken into account.
Tn (integral time, speed controller)
The integral time results from the estimated dynamic response of the speed control loop
(r5274).
Reference model
The reference model adapts the speed setpoint for the integrator input of the speed
controller to the dynamic response of the speed controller. This reduces speed overshoots
during setpoint changes.
Position controller
Two cases can be selected for the position control via bit p5271.0.
● p5271.0 = 0 (not active)
● p5271.0 = 1 (active)
The precontrol balancing is also adapted.
The balancing of the speed controller precontrol depends on parameters p5271 and p5275.
Drive functions
Function Manual, (FH1), 04/2014, 6SL3097-4AB00-0BP4
In this case, the position controller acts like a normal closed-loop P controller. The
position controller gain (servo gain factor) is adapted depending on the estimated
dynamic response of the speed control loop and the sample times.
If this bit is set and the estimated dynamic response (r5274) is greater than 16 ms, then
the first speed setpoint filter is parameterized as D filter. With the parameterization, the
gain for higher frequencies is greater and the filter has a more differentiated effect in the
bandwidth of the speed controller (larger phase reserve). This corresponds to a PD
controller. The servo gain factor may then be increased significantly.
Servo control
4.8 Autotuning
119