Rockwell Automation 20D PowerFlex 700S with Phase I Control Reference Manual - Manual (Page 82)

82 Rockwell Automation Publication PFLEX-RM002D-EN-E - August 2013
Chapter 1 Detail Drive Configuration and Operation
Position Loop - Follower
(Electronic Gearing) Technical Information
General facts about using the Position Loop for follower applications:
• Parameter 768 [PositReg P Gain] is used for tuning.
• Parameter 770 [Posit Reg Integ] is normally not needed for position
following applications and is disabled by factory default.
• The number of position counts per revolution depends on the type of
feedback device used:
• When using an encoder for positioning, the drive uses quadrature
counts. 1024 encoder = 4096 counts per motor revolution.
• When using a Stegmann absolute hi-resolution encoder, the drive
counts 1048576 counts per revolution.
• When using a Resolver, the drive counts 65536 counts per revolution.
• Speed regulator tuning directly affects the position loop performance. The
speed regulator should be tuned before the position loop.
• For best performance, positioning should be used with a dynamic brake or
regenerative system.
Overview
The position follower feature gives the user the ability to follow the position of a
master motor without an external position controller. The position loop adds to
or subtracts from the speed reference (using parameter 22 [Speed Trim 2]) to
correct for the following error and keep the positions of both encoders locked.
The resulting motor speed reference enters the speed regulator loop. Gear ratios
can be set up to follow at different rates of speed and position. Typical
applications for a geared follower would be for a roller following another part of a
machine, and a filler and capper machine for bottling.