Werbung
Verfügbare Sprachen
Verfügbare Sprachen
Optimization according to the step response method
Initially, a configurable standby output is produced until the actual value „settles" to a constant. This is automatically
followed by a configurable output level step (step size) to the control process.
E
Main applications of the step response method:
•
Optimization immediately after „power on" during startup (considerable time saving, standby output setting = 0 %)
•
Control process does not oscillate easily (for example, extremely well insulated furnace with low losses, long oscilla-
tion period)
•
Actual value must not exceed the setpoint value
If the output level is known for the corrected setpoint value, overshooting is prevented with the fol lowing setting:
Standby output + step size ≤ output level in corrected state
The progression of the output level and actual value depends on the status of the process at the point
when autotuning starts:
Autotuning during the startup phase
y
S
w
y = output level
y
= standby output
S
x = actual value
w = setpoint value
Optimized controller parameters
With both autotuning methods, the parameters for PI or PID controller structure are optimized according to the configu-
red controller type and the configured „Control structure" parameter:
proportional band Xp (P component), derivative time Tv (D component), and reset time Tn (I component).
The cycle time Cy and the filter time constant dF are also optimized.
Configured controller type Configured parameter
Two-state controller
y
}
Dy
x
t1 t2
t3
Control structure 1 = PI
All other settings
Product:
Temperature controller XT-T1
Autotuning during operation
y
y
S
t
x
w
t
t1
Dy = step size
t1 = start of autotuning
t2 = time of output level step
t3 = end of autotuning
Optimized parameters
Xp1, Tn1, Cy1, dF
Xp1, Tv1, Tn1, Cy1, dF
Revision 2.0 – Issue September 2018
{
Dy
t2
t3
Optimized con trol
structure
PI
PID
t
t
124/166
Werbung
