Rockwell Automation 25B PowerFlex 520-Series Adjustable Frequency AC Drive User Manual - Manual (Page 221)

Rockwell Automation Publication 520-UM001G-EN-E - September 2014 221
PID Set Up Appendix F
2. Adjust the integral gain (leave the proportional gain set as in Step 1). After
a step change in the PID Feedback:
–
If the response is too slow (see Slow Response – Over Damped on
page 221 ), or the PID Feedback does not become equal to the PID
Reference, decrease A462 or A474 [PID x Integ Time].
– If there is a lot of oscillation in the PID Feedback before settling out
(see
Oscillation – Under Damped on page 221 ), increase A462 or
A474 [PID x Integ Time].
3. At this point, the differential gain may not be needed. However, if after
determining the values for A461 or A473 [PID x Prop Gain] and A462 or
A474 [PID x Integ Time]:
–
Response is still slow after a step change, increase A463 or A475 [PID x
Diff Rate].
– Response is still unstable, decrease A463 or A475 [PID x Diff Rate].
The following figures show some typical responses of the PID loop at different
points during adjustment of the PID Gains.
Unstable Response
Slow Response – Over Damped
Oscillation – Under Damped
PID Feedback
PID Reference
Time
PID Feedback
PID Reference
Time
PID Feedback
PID Reference
Time