Problem Handling - Siemens SINAMICS S120 Function Manual

Position controller
Two cases can be selected for the position control via bit p5271.0:
● p5271.0 = 0 (not active)
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.
● p5271.0 = 1 (active)
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.
The precontrol balancing is also adapted. The balancing of the speed controller precontrol
depends on parameters p5271 and p5275.
Determining the maximum acceleration limits
Prerequisite is that the pulses have been disabled in the drive and the maximum moment of
inertia has been determined.
The maximum target acceleration for the basic positioner (EPOS) is determined with the aid of
the inertia estimator. This is performed only once after the activation of bit p5271.5. The load
torques and a control reserve of 20% are taken into account.
The user must decide to what extent this maximum acceleration is permissible for the
mechanical system of the machine (elastomechanical system) or for the thermal load capability
of the motor (depending on the load cycle). The calculated acceleration (p2572) or deceleration
(p2573) may have to be reduced by the commissioning engineer.
5.9.2.3

Problem handling

Possible problems and remedies are described in the following.
Drive vibrates
If the drive vibrates audibly, then the speed controller may have become instable at a
mechanical resonance.
Remedy
● The instability in the control loop through resonance can be avoided by parameterizing
band-stop filters in the current setpoint.
● Activate the adaptive resonance filter (see Section "Current setpoint filter adaptation
(Page 120)") and, if required, traverse forward and backward and wait a few seconds to see
whether the oscillation stops. If the whistling stops and also can no longer be heard during
operation, then the axis is ready.
● If required, the dynamic response of the axis can be decreased. To do this, the value of
parameter p5272 can be decreased.
Drive functions
Function Manual, 06/2019, 6SL3097-5AB00-0BP2
Servo control
5.9 Autotuning
119