Rockwell Automation 20G PowerFlex 750-Series AC Drives - Manual (Page 77)

Rockwell Automation Publication 750-RM002B-EN-P - September 2013 77
Drive Configuration Chapter 1
When the PID is disabled the commanded speed is the ramped speed reference.
When the PID is enabled the output of the PID Controller is added to the
ramped speed reference.
Exclusive Mode
In this mode, the output of PID regulator is the speed reference, and does not
“trim” a master speed reference. This mode is appropriate when speed is
unimportant and the only thing that matters is satisfying the control loop. In the
pumping application example below, the reference or setpoint is the required
pressure in the system. The input from the transducer is the PID feedback and
changes as the pressure changes. The drive output frequency is then increased or
decreased as needed to maintain system pressure regardless of flow changes. With
+
+
+
+
Slip Adder
Spd Ref
PID Ref
PID Fbk
Process PID
Controller
PID Disabled Speed Control
Linear Ramp
and S Curve Spd Cmd
Slip
Comp
Open
Loop
Process
PID
+
+
+
+
Slip Adder
Spd Ref
PID Ref
PID Fbk
Process PID
Controller
PID Enabled Speed Control
Linear Ramp
and S Curve Spd Cmd
Slip
Comp
Open
Loop
Process
PID