3. Instruction Set
G(s)
S
1/S K
I
K
P
K
D
+
+
+
PID
operation is within dotted area
+
The equation above illustrates that this operation is different from a general PID operation
on the application of the derivative value. To avoid the fault that the transient derivative
value could be too big when a general PID instruction is first executed, our PID instruction
monitors the derivative value of the PV. When the variation of PV is excessive, the
instruction will reduce the output of MV/.
2. When control mode (S
3
+4) is selected as K3 and K4:
The equation is exclusively for temperature control will be modified as:
( )
( ) ( )
+
+= StEK
S
tE
K
tE
K
MV
D
IP
*
111
,
where
Control diagram:
In diagram below, 1/K
I
and 1/K
P
refer to “divided by K
I
” and “divided by K
P
”. Because this
mode is exclusively for temperature control, users have to use PID instruction together
with GPWM instruction. See Application 3 for more details
G(s)
S
1/S
1/K
I
K
D
+
+
+
PID operation is within dotted area
P
+
1/K
This equation is exclusively designed for temperature control. Therefore, when the
sampling time (T
S
) is set as 4 seconds (K400), the range of output value (MV) will be K0 ~
K4,000 and the cycle time of GPWM instruction used together has to be set as 4 seconds
(K4000) as well.
To Next Page
Loading...
Need help?
General
