Mitsubishi Electric MELSEC iQ-R Series Programming Manual page 2059

Overview of step response method
This section describes the step response method that is used to determine the optimum value of three PID constants
(proportional gain (K ), integral time (T
P
■Step response method
This method determines the three PID constants according to the operation characteristics (maximum ramp (R), dead time
(L)) that can be determined from input changes by providing the control system with stepwise output of 0100%
*1 Stepwise output can also be determined by 075% or 050%.
■Operation characteristics
100%
MV
0%
Rate of change
in input value
L
MV: Manipulated value
L: Dead time
R: Maximum ramp
t: Time
■Operation characteristics and three constants
Control method Proportional gain (K
Proportional control (P action)
only
PI control (PI action)
PID control (PID action)
), and derivative time (T
I
MV
t
R
t (s)
1 (s)
) [%]
P
1
× MV × 100
RL
0.9
× MV × 100
RL
1.2
× MV × 100
RL
)).
D
Integral time (T ) [100ms]
I

33L
20L
Appendix 3 Determining Three PID Constants
*1
.
Derivative time (T ) [10ms]
D


50L
APPX
2057
A