Mitsubishi Electric MELSEC iQ-R Series Programming Manual page 291

• BPI operations are conducted as follows.
Item Direct action
Deviation (DVn) DVn = PVn - SVn
Output variation (MV)
ΔMV=Kp×ΔT×{DV
Kp: Gain
Ti: Integral time
T: Execution cycle
CT: Control cycle
DVi: DVn cumulative value
DVn: Deviation
PVn: Process variable
SVn: Engineering value conversion processing result
The integral term and derivative term are as follows under the following conditions.
Condition
Ti = 0
When MLA is TRUE
When MHA is TRUE
Ti  0
Ti: Integral time
CT: Control cycle
DVi: DVn cumulative value
DVn: Deviation
MLA: Output low limit alarm
MHA: Output high limit alarm
Set an integral multiple of the execution cycle (T) as a control cycle (CT).
Set 0.0 or a value equal to or larger than the control cycle (CT) as an integral constant.
PID operations of this tag access FB are performed every control cycle (CT) (MV output).
In other execution cycles (T), the last value is held (MV = 0).
■Engineering value conversion
This function block converts the setting value (%) from the primary loop in the CAS or CSV mode into an engineering value.
RH-RL
×
SV= Setting value (%) from the primary loop + RL
100
RH: Engineering value high limit, RL: Engineering value low limit, SV: Setting value
■Inverse engineering value conversion
This function block converts the setting value (SV) of an engineering value into a setting value (SV) in percentage (%).
100
SV(%)= ×(SV-RL)
RH-RL
RH: Engineering value high limit, RL: Engineering value low limit, SV: Setting value
CT
+ ×ΣDV }
n i
Ti
Processing
CT
×ΣDV
Ti
CT
×ΣDV
Ti
10.18 Blend PI Control (Disable Tracking for primary loop) (M+P_BPI)
Reverse action
DVn = SVn - PVn
= Hold the previous value
i
CT
= ×(ΣDV +DV )
i i n
Ti
10 LOOP CONTROL OPERATION
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