Shinko FCD-13A - 10.3 AT (auto-tuning) of this controller

50
10.3 AT (auto-tuning) of this controller
In order to set each value of P, I and D automatically, AT process should be made to
fluctuate to obtain an optimal value.
Sometimes the AT process will not fluctuate if AT is performed at or near room
temperature. Therefore AT might not finish normally.
(A) In the case of a large difference between the SV and PV as the temperature is
rising
The AT process will fluctuate at the temperature 1.5% of input span lower than the SV.
(DC input: 1.5% of scaling span)
(1) Calculating PID
constant
(2) PID constant
calculated
(3) Controlled by the
PID constant set
by AT.
(4) 1.5% of input span
(Fig. 10.3-1)
(B) When the control is stable or when PV is within SV (1.5% of input span).
The AT process will fluctuate around the SV. (DC input: 1.5% of scaling span)
(1) Calculating PID
constant
(2) PID constant
calculated
(3) Controlled by the
PID constant set
by AT.
(Fig. 10.3-2)
(C) When the PV is 1.5% of input span higher than the SV
The AT process will fluctuate at the temperature 1.5% of input span higher than the SV.
(DC input: 1.5% of scaling span)
(1) Calculating PID
constant
(2) PID constant
calculated
(3) Controlled by the
PID constant set
by AT.
(4) 1.5% of input span
(Fig. 10.3-3)
(1)
(2) (3)
(4)
AT starting point
SV
Temperature
Time
1.5% of input span lower than the SV
AT starting point
(1)
(2)
(3)
Temperature
SV
Time
1.5% of input span higher than the SV
AT starting point
(1)
(2) (3)
(4)
Temperature
SV
Time