Siemens SIMATIC S5-115U, User Manual

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Integral Blocks S5-115U Manual
Correction Rate Algorithm
The relevant correction increment dY
k
is computed at instant t= k
•
TA according to the following
formula:
• Without feedforward control (D11.5=1); XW is forwarded to the differentiator (D11.1=0)
dY
k
= K[(XW
k
- XW
k-1
) R+TI
•
XW
k
+ (TD (XW
k
- 2XW
k-1
+ XW
k-2
) + dD
k-1
)]
= K (dPW
k
+ dI
k
+ dD
k
)
• With feedforward control (D11.5=0); XW is forwarded to the differentiator (D11.1=0)
dY
k
= K[(XW
k
- XW
k-1
) R+TI
•
XW
k
+ (TD (XW
k
- 2XW
k-1
+ XW
k-2
) + dD
k-1
)]+(Z
k
-Z
k-1
)
= K (dPW
k
+ dI
k
+ dD
k
)+dZ
k
• Without feedforward control (D11.5=1); XZ is forwarded to the differentiator (D11.1=1)
dY
k
= K[(XW
k
- XW
k-1
) R+TI
•
XW
k
+ (TD (XZ
k
- 2XZ
k-1
+ XZ
k-2
) + dD
k-1
)]
= K (dPW
k
+ dI
k
+ dD
k
)
• With feedforward control (D11.5=0); XZ is forwarded to the differentiator (D11.1=1)
dY
k
= K[(XW
k
- XW
k-1
) R+TI
•
XW
k
+ (TD (XZ
k
- 2XZ
k-1
+ XZ
k-2
) + dD
k-1
)]+(Z
k
-Z
k-1
)
= K (dPW
k
+ dI
k
+ dD
k
)+dZ
k
Z component P component I component D component k: k th sample
When XW
k
is applied: XW
k
= W
k
- X
k
PW
k
= XW
k
- XW
k-1
QW
k
= PW
k
- PW
k-1
= XW
k
-2XW
k-1
+XW
k-2
When XZ is applied: PZ
k
= XZ
k
- XZ
k-1
QZ
k
= PZ
k
- PZ
k-1
= XZ
k
-2XZ
k-1
+XZ
k-2
The result is: dPW
k
= (XW
k
- XW
k-1
)R
dI
k
= TI
•
XW
k
dD
k
= (TD
•
QW
k
+dD
k-1
) when XW is applied
= (TD
•
QZ
k
+dD
k-1
) when XZ is applied
dZ
k
= Z
k
- Z
k-1
Correction Algorithm
The formula used to compute the correction rate algorithm is also used to compute the correction
algorithm.
In contrast to the correction rate algorithm, however, the sum of all correction increments
computed (in DW 48), rather than the correction increment dY
k
is output at sampling instant t
k
.
11-36
EWA 4NEB 811 6130-02b