Pid Auto-Tuning - Panasonic KT2 Instruction Manual

9. PID auto-tuning

In order to set each value of P, I, D and ARW automatically, the auto-tuning process should be made to
fluctuate to obtain an optimal value.
Notice
• Perform auto-tuning during trial run.
• During auto-tuning, none of the setting items can be set.
• If auto-tuning starts during program control run, auto-tuning performs with SV at which auto-tuning
starts. The step time does not progress until auto-tuning ends.
• If power failure occurs during auto-tuning, auto-tuning stops.
• For DC input, the AT process will fluctuate around the SV for conditions of (A), (B) and (C) below.
• Sometimes the auto-tuning process will not fluctuate if auto-tuning is performed at or near room
temperature. Therefore auto-tuning might not finish normally.
(A) In the case of a large difference between the SV and processing temperature as the
temperature is rising
When AT bias is set to 20 , the AT process will fluctuate at the temperature 20
Temperature 20
the SV
SV
Temperature
AT starting point
(B) In the case of a stable control
The AT process will fluctuate around the SV.
SV
Temperature
(C) In the case of a large difference between the SV and processing temperature as the
temperature is falling
When AT bias is set to 20 , the
the SV.
Temperature
SV
lower than
(4)
(1)
(2)
AT starting point
(1)
(2)
AT process will fluctuate
Temperature 20
the SV
(4)
AT starting point
(1)
Time
(Fig. 9-1)
(3)
Time
(Fig. 9-2)
(3)
at the temperature 20
higher than
Time
(Fig. 9-3)
(3)
(2)
22
lower than the SV.
(1) Calculating PID constant
(2) PID constant calculated
(3) Controlled by the PID constant
set by auto-tuning.
(4) AT bias value
(1) Calculating PID constant
(2) PID constant calculated
(3) Controlled by the PID constant
set by auto-tuning.
(1) Calculating PID constant
(2) PID constant calculated
(3) Controlled by the PID constant
set by auto-tuning.
(4) AT bias value
higher than