LSIS Master-K K200S - Reference Value

Chapter 15 The PID function of K200S MASTER-K
15-9
15.2.6 Reference value
In general feedback control system shown as the figure 15.11, the deviation value is
obtained by the difference of PV and SV. P, I, and D operations are performed based on
this deviation value. However, each of P, I, and D operations use different deviation
values according to the characteristics of each control actions. The expression of PID
control is as following;






++=
∫
t
dt
dEd
TddssEi
Ti
EpKMV
0
)(
1
MV : Manipulate value
K : Proportional gain
Ti : Integral time
Td : Derivative time
Ep : Deviation value for proportional action
Ei : Deviation value for integral action
Ed : Deviation value for derivative action
The deviation values of P, I, and D action is described as following equations;
PVEd
PVSVEi
PVSVbEp
−=
−=
−
×
=
The b if the first equation is called as reference value. It can be varied according to the
load disturbance of measurement noise.
Fig. 15.11 Diagram of simple feedback control system
Process
-1
+
SV PV MV
PID
controller