Rockwell Automation 20M LPM15 Liquid-Cooled Adjustable Frequency AC Drive FRN 2.xxx - Manual (Page 116)

D-6 Application Notes
Process PI The internal PI function of the LPM15 provides closed loop process control
with proportional and integral control action. The function is designed for
use in applications that require simple control of a process without external
control devices. The PI function allows the microprocessor of the drive to
follow a single process control loop.
The PI function reads a process variable input to the drive and compares it
to a desired setpoint stored in the drive. The algorithm will then adjust the
output of the PI regulator, changing drive output frequency to try and make
the process variable equal the setpoint.
It can operate as trim mode by summing the PI loop output with a master
speed reference.
Or, it can operate as control mode by supplying the entire speed reference.
This method is identified as “exclusive mode.”
PI Enable
The output of the PI loop can be turned on (enabled) or turned off
(disabled). This control allows the user to determine when the PI loop is
providing part or all of the commanded speed. The logic for enabling the PI
loop is shown below.
+
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
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
Drive
Running
Drive
Ramping
to Stop
Drive
Jogging
Bit 0 of
[PI Control] = 1
(enabled)
[PI Configuration]
Signal Loss
The Configured
Digital Input
is Closed
A Digital Input
is Configured
to PI Enable
"Enabled" Status
Digital Input
is Reflected
in [PI Status]
Bit 0 = 1
The PI Loop
is Enabled
Bit 0 Bit 6