Process PI Loop 2-139
When the PI is enabled, the output of the PI Controller is added to the
ramped speed reference.
Exclusive Control
Process Control takes the output of PI regulator as the speed command. No
master speed reference exists and the PI Output directly controls the drive
output.
In the pumping application example below, the reference or setpoint is the
required pressure in the system. The input from the transducer is the PI
feedback and changes as the pressure changes. The drive output frequency
is then increased or decreased as needed to maintain system pressure
+
Spd Cmd
Process PI
Controller
Linear Ramp
& S-Curve
+
+
+
PI Disabled
Speed Control
Spd Ref
PI Ref
PI Fbk
Slip Adder
Open
Loop
Slip
Comp
Process
PI
+
Spd Cmd
Process PI
Controller
Linear Ramp
& S-Curve
+
+
+
PI Enabled
Speed Control
Spd Ref
PI Ref
PI Fbk
Slip Adder
Open
Loop
Slip
Comp
Process
PI