Siemens SINAMICS G120 Operating Instructions Manual page 277

Autotuning of the PID controller
Autotuning is an inverter function for the automatic optimization of the PID controller.
For active autotuning, the inverter interrupts the connection between the PID controller and
the speed controller. Rather than the PID controller output, the autotuning function provides
the speed setpoint.
Figure 6-32
The speed setpoint results from the technology setpoint and a superimposed rectangular signal
with amplitude p2355. If actual value = technology setpoint ± p2355, the autotuning function
switches the polarity of the superimposed signal. This causes the inverter to excite the process
variable for an oscillation.
Figure 6-33
The inverter calculates the parameters of the PID controller from the determined oscillation
frequency.
Converter with the CU230P-2 Control Units
Operating Instructions, 09/2017, FW V4.7 SP9, A5E34257946B AE
Autotuning of the PID controller using the example of a filling-level control
Example for speed setpoint and actual process value for autotuning
Advanced commissioning
6.18 PID technology controller
277