Mitsubishi Electric MELSEC iQ-R Series User Manual page 120

Feed forward control
When an external factor that disturbs the control occurs, this control executes a corrective action to eliminate the effect to
temperatures in advance.
The temperature fall (bottom) caused by the disturbance is suppressed by adding the feed forward value to an output.
The adjustment of the feed forward value can be selected from manually and automatically in 'CH1 Feed forward value tuning
selection' (Un\G561).
FF value is added.
Set value
(SV)
PID control
PID control after the bottom control
After the bottom has been suppressed by the feed forward control, the control is shifted to the PID control.
In this case, overshoots may occur. Thus, the overshoot value and the recovery time need to be adjusted for the recovery
operation to the set value (SV).
Select the set value (SV) restoration adjustment level from 0 to 10 and adjust the overshoot value and the recovery time.
31.0
30.5
Set value
30.0
(SV)
29.5
29.0
28.5
28.0
0
(1) PID control (no return adjustment)
(2) Return adjustment value: Small
(3) Return adjustment value: Large
1 FUNCTIONS
118
1.35 Disturbance Suppression Function
FF control
20
FF control
Process value (PV)
Manipulated value (MV)
PID control
(1)
(2)
(3)
40 60
Time [s]
PID control
80 100