Rockwell Automation Allen-Bradley PowerFlex 700S - Page 85

Rockwell Automation Publication PFLEX-RM003E-EN-E - January 2011 85
Detailed Drive Operation Chapter 1
Note: making parameter 727 [PLL VirtEncdrRPM] = 1200 will scale PLL speed
to a pu system based on rated line speed. This makes sense because there is no
common base RPM of the motors given their different ratios.
Further analysis shows that a 2048 line encoder provides adequate resolution for
unit to folder registration and it is easy to install. The line encoder will be wired
to encoder 1.
• Set parameter 725 [PLL EPR Input] = 8192
• Link parameter 721 [PLL Position Ref ] to parameter 240 [Encdr1
Position]
All motors will be equipped with 2048 count per revolution encoders. The PLL
is set up for the equivalent edges per revolution:
• Set parameter 726 [PLL EPR Output] = 2048 x 4 = 8192
Setup the folder’s encoder speed reference as the feed forward because it is
disturbance free:
• Link parameter 728 [PLL Ext Spd Ref ] to parameter 241 [Encdr1 Spd
Fdbk]
• Set parameter 720 [PLL Control], bit 0 “Vel FdFwd En” = 1 to enable the
speed feed forward
• Set parameter 720 [PLL Control], bit 1 “Ext Vel In” = 1 to enable the
external feed forward
• Adjust parameter 729 [PLL Ext SpdScale] until you get zero at parameter
733 [PLL FiltPositOut]
• Set parameter 730 [PLL LPFilter BW] to the equivalent bandwidth of the
folder’s DC drive
In the local drive (the drive implementing the PLL), set up the speed and position
loops to follow the PLL output:
• Link parameter 12 [Speed Ref 2] to parameter 734 [PLL Speed Out]
• Set parameter 13 [Spd Ref2 Mutli] = 1
• Set parameter 27 [Speed Ref A Sel] = 2 “Speed Ref 2"
• Set parameter 147 [FW Function En], bit 16 “PositionCtrl” = 1
• Set parameter 151 [Logic Command], bit 1 “SpdRamp Dsbl” = 1
• Set parameter 151 [Logic Command], bit 13 “Position En” = 1
• Set parameter 742 [Position Ref Sel] = 1 “AuxPosit Ref ”
• Link parameter 743 [Aux Posit Ref ] to parameter 731 [PLL Posit Out]
• Set parameter 745 [PositRef EGR Mul] = 1
• Set parameter 746 [PositRef EGR Div] = 1
Broadcast parameter 735 [PLL SpeedOut Adv] and parameter 732 [PLL Posit
OutAdv] over SynchLink. Setup the speed reference in the follower drives to
follow [PLL SpeedOut Adv] received over Synchlink. Setup the position
reference in the follower drives to follow [PLL Posit OutAdv] received over