Mitsubishi Electric a2 Series - Page 109

α 2 Simple Application Controllers
Function Blocks 6
6 - 55
Table 6.25: PID Equations
Filtered Process Value
Filtered Set Value
Deflection (Error Value)
Integration Value
Derivative Value
Control Value Change in
Forward Operation
Control Value Change in
Reverse Operation
Manipulation Value
Table 6.26: List of Additional Variables used in the PID equations
Variable Description
EV
n
Deflection for current sample
EV
n-1
Deflection of previous sample
I
n
Intergration Value for current sample
K
D
Derviative Gain
K
P
Proportional Gain
MV
n
Output Value for current sample (Manipulated Value)
PV
fn
Measured Value (filtered) for current sample
PV
fn-1
Measured Value (filtered) for previous sample
PV
fn-2
Measured Value (filtered) for two samples ago
PV
n
Measured Value for current sample
SV
fn
Set Value (filtered) for current sample
SV
fn-1
Set Value (filtered) for previous sample
SV
n
Set Value for current sample
SV
n-1
Set Value for previous sample
T
D
Dervative Time
()
nfnfnfn
PVPVPVPV
−+=
−
1
á
()
()
11
1
−−
+−+
+
=
fnInnInS
IS
fn
SVTSVSVTSVT
TT
SV
βαβ
β
fnfnn
SVPVEV
−=
n
I
S
n
EV
T
T
I
=
()
121
2
−−−
++−
+
=
nDfnfnfn
DDS
D
n
DKPVPVPV
TKT
T
D
()()
nnnnPn
DIEVEVKMV
++−=∆
−
1
()()
nnnnPn
DIEVEVKMV
++−−=∆
−
1
∑
∆=
nn
MVMV