Mitsubishi a2 Series Programming Manual page 115

α
2 Simple Application Controllers
Table 6.25: PID Equations
Filtered Process Value
Filtered Set Value
Deflection (Error Value)
Integration Value
Derivative Value
C o n t r o l Va l u e C h a n g e i n
Forward Operation
C o n t r o l Va l u e C h a n g e i n
Reverse Operation
Manipulation Value
Table 6.26: List of Additional Variables used in the PID equations
Variable
EV
Deflection for current sample
n
EV
Deflection of previous sample
n-1
I
Intergration Value for current sample
n
K
Derviative Gain
D
K
Proportional Gain
P
MV
Output Value for current sample (Manipulated Value)
n
PV
Measured Value (filtered) for current sample
fn
PV
Measured Value (filtered) for previous sample
fn-1
PV
Measured Value (filtered) for two samples ago
fn-2
PV
Measured Value for current sample
n
SV
Set Value (filtered) for current sample
fn
SV
Set Value (filtered) for previous sample
fn-1
SV
Set Value for current sample
n
SV
Set Value for previous sample
n-1
T
Dervative Time
D
=
PV
fn
(
1
=
SV T SV
+ β
fn S
T T
S I
EV
(
T
=
D
D
n +
T K T
S D D
∆ =
MV K
n
∆ = −
MV K
n
Description
(
+ −
á
PV PV PV
−1
n f fn
(
αβ
+ −
T SV SV
−
n I n n
= −
PV SV
n fn fn
T
I =
S
EV
n n
T
I
− +
PV 2 PV PV
−
fn fn 1 fn
( ( )
− + +
EV EV I
−1
P n n n
( ( )
− +
EV EV I
−1
P n n n
∑
= ∆
MV MV
n n
Function Blocks 6
)
n
)
)
β
+
T SV
−
1 I fn 1
)
+
K D
− −
2 D n 1
)
D
n
)
+
D
n
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