Adaptation Of The Control Parameters - Siemens SINAMICS S120 Function Manual

Servo control
5.9 Autotuning
Application examples
Online tuning is applied in the following cases:
● Positioning axes
A positioning axis application can always be used when an axis performs a point-to-point
motion independently of other axes. p5302.7 = 0 must be set. The axis is thus optimized for
positioning without overshoot.
● Interpolating axes (EPOS position controller with higher-level control)
Interpolating axis applications are required when several axes jointly perform a path motion,
for example, in which the deviation to the contour should be as small as possible. Parameter
p5302.7 = 1 must be set. The precontrol must not be switched off subsequently.
The controlled dynamic response is set with parameter p5275. All interpolating axes must
have the same value.
With values that are too small, the axis can overshoot during positioning. If this has a
negative effect on the application, the value in p5275 must be increased in all axes. The axis
with the largest estimated time constant (r5274) in the settled state is the determining axis.
5.9.2.2

Adaptation of the control 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.
118
Function Manual, 06/2019, 6SL3097-5AB00-0BP2
Drive functions