Rockwell Automation 284E ArmorStart with EtherNet/IP - User Manual - Manual (Page 327)

Rockwell Automation Publication 280E-UM001B-EN-P – July 2012 327
Appendix
D
PID Setup
PID Loop The Bulletin 284E ArmorStart® Distributed Motor with sensorless vector control
has a built-in PID (proportional, integral, differential) control loop. The PID
loop is used to maintain a process feedback (such as pressure, flow, or tension) at a
desired set point. The PID loop works by subtracting the PID feedback from a
reference and generating an error value. The PID loop reacts to the error, based
on the PID Gains, and outputs a frequency to try to reduce the error value to 0.
To enable the PID loop, Parameter 232 (PID Ref Sel) must be set to an option
other than Option 0 (PID Disabled).
Exclusive Control and Trim Control are two basic configurations where the PID
loop may be used.
Exclusive Control
In Exclusive Control, the Speed Reference becomes 0, and the PID Output
becomes the entire Freq Command. Exclusive Control is used when
Parameter 232 (PID Ref Sel) is set to Option 1, 2, 3, or 4. This configuration
does not require a master reference, only a desired set point, such as a flow rate for
a pump.
Example
• In a pumping application, the PID Reference equals the Desired System
Pressure set point.
• The Pressure Transducer signal provides PID Feedback to the drive.
Fluctuations in actual system pressure, due to changes in flow, result in a
PID Error value.
• The drive output frequency increases or decreases to vary motor shaft
speed to correct for the PID Error value.
–
+
PID Prop Gain
PID Loop
PID Integ Time
PID Diff Rate
PID Enabled
PID Fdbk
PID Ref
PID
Error
+
+
+
PID
Output
Accel/Decel
Ramp
Freq
Command