YOKOGAWA UT55A - Batch PID Control (Performing Control with Rapidly Settling Setpoints)

8-83
IM 05P01C31-01EN
Control Functions
8.2.7 BatchPIDControl(PerformingControlwithRapidlySettlingSetpoints)
Description
BatchPIDcontrolisusefulforcaseswherecontrolisperformedcausingthePVtosettle
to a target setpoint (SP) as quickly as possible without overshooting.
If a deviation (E) exceeding a batch PID deviation setpoint (BD) occurs, the controller
outputs
thecontrol
outputhighlimit(OH)toquicklybringthePVtotheSP(inthecaseof
reverse action).
If a deviation (E) falls within the batch PID deviation setpoint (BD), the controller
determines that the process is in a steady state and changes to PID control.
Upon changing to PID control, the controller starts to output from
OUT
=OH
−BB
toavoidanovershootinthePV.
where batch PID bias (BB): Amount of output pulled back
If the deviation (E) exceeds the batch PID deviation setpoint (BD) after the controller has
switched to PID control (steady state), no control output high limit (OH) will be output
unless the deviation exceeds the batch PID lock-up width (BL).
Moreover, in the case of direct action, the controller outputs the control output low limit (OL)
instead of the control output high limit (OH), making the batch PID bias (BB) act in the
positive direction.
The following shows the action in Batch PID control.
Batch PID control is started as MAN is changed into AUTO.
OH outputOH output PID control output
BDBLBD
SP
Time
PV
(M) (A)
Start of batch PID control
BB
OUT
OH
BB
Occurrence of disturbance
whereOUT:controloutput,OH:outputhighlimit,SP:targetsetpoint,andPV:measuredinput
8
8.2SettingControlType(CNT)