Selection Of The Controller Structure For Specified Controlled Systems - Siemens SIMATIC S7-1200 Function Manual

Principles for control

2.7 Selection of the controller structure for specified controlled systems

2.7 Selection of the controller structure for specified controlled systems
Selection of the Suitable Controller Structures
To achieve optimum control results, select a controller structure that is suitable for the
controlled system and that you can adapt to the controlled system within specific limits.
The table below provides an overview of suitable combinations of a controller structure and
controlled system.
Controlled system
With dead time only
PT1 with dead time
PT2 with dead time
Higher order
Not self-regulating
The table below provides an overview of suitable combinations of a controller structure and
physical quantity.
Physical quantity
Temperature
Pressure
Flow rate
36
P
Unsuitable Unsuitable
Unsuitable Unsuitable
Unsuitable Suited conditionally Well suited
Unsuitable Unsuitable
Well suited Well suited
P
Sustained control deviation
For low perfor- Well suited
mance require-
ments and
proportional action
controlled systems
with T /Tg < 0,1
u
Suitable, if the Unsuitable
delay time is in-
considerable
Unsuitable, be- Unsuitable
cause required
GAIN range is
usually too large
Controller structure
PD PI
Suitable
Well suited
Suited conditionally Well suited
Well suited
Controller structure
PD PI
No sustained control deviation
The most suitable controller structures
for high performance requirements
(except for specially adapted special
controllers)
The most suitable controller structures
for high performance requirements
(except for specially adapted special
controllers)
Suitable, but inte-
gral action control-
ler alone often
better
Function Manual, 03/2017, A5E35300227-AC
PID
Unsuitable
Well suited
Well suited
Well suited
PID
Hardly required
PID control