Rockwell Automation 20A PowerFlex 70EC/700VC - Manual (Page 86)

82 Process PID Loop
•
Stop Mode - When Stop Mode is set to “1” and a Stop command is issued to the
drive, the PID loop will continue to operate during the decel ramp until the PID
output becomes more than the master reference. When set to “0,” the drive will
disable PID and perform a normal stop. This bit is active in Trim mode only.
•
Anti-Wind Up - When Anti-Windup is set to “1” the PID loop will
automatically prevent the integrator from creating an excessive error that could
cause loop instability. The integrator will be automatically controlled without
the need for PID Reset or PID Hold inputs.
•
Torque Trim - When Torque Trim is set to “1” the output of the process PID
loop will be added to Torque Reference A and B, instead of being added to the
speed reference. Torque Trim is only active in Flux Vector mode.
•
% of Ref - When using Process PID control the output can be selected as
percent of the Speed Reference. This works in Speed trim mode only, not in
Torque Trim or Exclusive Mode.
Examples
% of Ref selected, Speed Reference = 43 Hz, PID Output = 10%, Maximum Frequency = 130 Hz.
4.3 Hz will be added to the final speed reference.
% of Ref not selected, Speed Reference = 43 Hz, PID Output = 10%, Maximum Frequency = 130
Hz. 13.0 Hz will be added to the final speed reference.
PID Control
[PI Control] is a set of bits to dynamically enable and disable the operation of the
process PID controller. When this parameter is interactively written to from a
network it must be done through a data link so the values are not written to
EEprom.
•
PI Enable - The PID loop can be enabled/disabled. The Enabled status of the
PID loop determines when the PID regulator output is part or all of the
commanded speed. The logic evaluated for the PID Enabled status is shown in
the following ladder diagram.
The drive must be in Run before the PID Enabled status can turn on. The PID
will remain disabled when the drive is jogged. The PID is disabled when the
drive begins a ramp to stop, except when it is in Trim mode and the Stop mode
bit in [PI Configuration] is On.
-100.0 -75.0 -50.0 -25.0 0.0 25.0 50.0 75.0 100.0
Normalized Feedback
Nor
maliz
ed SQR
T(F
eedbac
k)
-100.0
-75.0
-50.0
-25.0
0.0
25.0
50.0
75.0
100.0