Rockwell Automation FlexPak 3000 Digital DC Drive Version 4.3 - Manual (Page 103)

Configuring the Outer Control Loop 9-9
9.3 Configuring the Outer Control Loop Feedback Path
The OCL lead and lag options allow you to limit ratio errors when the primary ratio
variable changes quickly. Lead/lag adjustments compensate for backlash or coupling
issues with the feedback device.
To enable lead/lag or lag/lead, set OCL LEADLAG SELECT to LEAD / LAG or LAG / LEAD ,
respectively. To disable lead/lag or lag/lead, set OCL LEADLAG SELECT to BYPASS .
When lead/lag or lag/lead is selected, the OCL accepts a feedback signal from the
source selected by OCL FEEDBACK SELECT (P.804). You can check the value of this
signal through OCL FEEDBACK (P.847).
OCL FEEDBACK is fed into the lead/lag block. In this block, the OCL LEADLAG LOW FREQ
(P.806) and OCL LEADLAG RATIO (P.807) values are applied to the signal and the drive
calculates the high break frequency. OCL LEADLAG LOW FREQ sets where the signal will
break. The OCL LEADLAG RATIO is the ratio maintained between the low break and high
break frequency. The low frequency and ratio settings are multiplied to determine the
high break frequency. For example, if the low break frequency is 0.50 rad/s and the
ratio is 10, the high break frequency is 5.00 rad/s.
The transfer functions for lead/lag and lag/lead are:
!
ATTENTION: Lead/lag parameters must be adjusted by a qualified
control engineer. Failure to observe this precaution can result in severe
bodily injury or loss of life.
Lead/Lag: Lag/Lead: Where:
• ω
low
= OCL LEADLAG LOW FREQ (P.806)
• ω
high
= OCL LEADLAG LOW FREQ (P.806)
*
OCL LEADLAG RATIO (P.807)
1
s
ω
low
---------- +
1
s
ω
high
------------ +
----------------------
1
s
ω
high
------------ +
1
s
ω
low
---------- +
----------------------
OCL FEEDBACK
(P.847)
The feedback value
of the outer control
loop. It is displayed in
OCL user-defined
units.
Parameter Range: n/a
Default Setting: n/a
Parameter Type: Output
OIM Menu Path(s): Outer Control Loop ( OCL ) - OCL Test Points