Rockwell Automation 20D PowerFlex 700S AC Drives with Phase II Control Reference Manual - Manual (Page 90)

90 Rockwell Automation Publication PFLEX-RM003E-EN-E - January 2011
Chapter 1 Detailed Drive Operation
Position Loop - Follower
(Electronic Gearing) General facts about using the Position Loop for follower applications:
• Parameter 768 [PositReg P Gain] is used for tuning.
• Parameter 770 [PositReg 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, i.e., 1024 encoder = 4096 counts per motor revolution.
– When using a Stegmann 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 in the PowerFlex 700S 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.