Rockwell Automation 20D PowerFlex 700S with Phase I Control Reference Manual User Manual
Page 58
58
Rockwell Automation Publication PFLEX-RM002D-EN-E - August 2013
Chapter 1
Detail Drive Configuration and Operation
The lead term (Wld) is used to display the lead of the filter. The lag term (Wlg) is
used to show the lag of the filter.
shows the bode plot of the lead function. The lead term is used to
counteract lags in the system. The speed loop bandwidth appears to the position
loop as a low pass filter or a lag. The lead filter can be used to cancel the speed
loop lag and replace it with a faster lag.
Figure 17 - Kn > 1 “Lead Filter”
In the following example:
•
The system appears as a lag with a 5 rad/sec response.
•
The lead filter was set to compensate for the 5 rad/sec response (Wld=5)
•
The lag filter was set to 50 rad/sec response (Wlg=50)
•
Kn is set to Wlg/Wld (50/5) = 10
•
Wn is set to Wlg = 50
Kn
s
wn
+
×
s
wn
+
------------------------------
Kn
s
wn
1
+
(
)
⁄
×
s
wn
1
+
(
)
⁄
---------------------------------------------
s
Wld
1
+
(
)
⁄
s
Wlg
1
+
(
)
⁄
----------------------------------
wn
Wlg
=
Kn
Wlg
Wld
----------
=