Rockwell Automation 9329 Drive Application Software Tension Control Gen. Units - Manual (Page 43)

FM – Tension Control
Drive Application Software – page 43 of 52
6.3.2 Trim_KP
The Trim_KP is the proportional term of the PI. The PI Regulator Error is multiplied
by tis value. It is scaled such that a value of one, would produce 100% output of the
regulator when there is 100% error. If the reference was 100% and the feedback
was 0%, than the error would be 100%.
Notice that the step response does not reach its final value. This is known as steady
state error.
Typically this value is increased until the trim regulator appears to be unstable and
then is backed off 30%.
6.3.3 Trim_wld
The Trim_wld term is the lead frequency for the PI regulator. The term wld is
(integral Gain/proportional gain). This term affects the steady state error of the
regulator. The above plot only has KP, therefore there is a steady state error.
Typically after the KP term is set, than the wld term is increased untill the desired
steady state response is achieved.
0 10 20 30 40 50 60 70 80 90 100
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
effects of KP
amlitude
time in seconds
KP=10
KP=1
KP=0.1