Rockwell Automation 8720MC Drives Integration Manual - Manual (Page 38)

Publication 8720MC-IN002A-EN-P — December 2002
2-6 Commissioning Your 8720MC Analog Drive
Understanding Servo Loop
Parameters This section provides the information you will need to select and
adjust servo loop parameters.
One of the most important tasks to be performed during startup is the
adjustment of the servo loop parameters. Adjustment of these
parameters is essential to get the maximum performance from a drive
application. The 8720MC is supplied with a set of default parameters
which are intended to provide a good starting point. In addition all
the motor-specific parameters are stored in the motor encoder.
As a consequence, only a few key servo loop parameters require
tuning to the specific load and application.
The traditional method of tuning the servo loop parameters is
performed by a process of trial and error adjustment. The 8720MC
drive provides an auto tuning procedure which greatly simplifies this
task. Eight sets of servo loop parameters (selectable via digital inputs
on P5-16 through P5-18) are shown in Parameter Files, Groups, and
Elements (Group Listing) in Appendix C. Each group has 16 servo loop
parameters or “elements” of which 4 are set by the auto tuning
procedure. The 8 groups of servo loop parameters are provided to
support multiple gear ranges, high /low winding motors and multiple
operating modes. Each unique gear range, winding or operating mode
requires a separates set of servo loop parameters and each should be
separately auto tuned. Auto tuning compensates for the changes in the
reflected inertia and changes in the motor operating characteristics
caused by gear changes or switching the high/low winding.
Selecting a Servo Loop Parameter Group
Before you begin auto tuning it is necessary to select the servo loop
parameter group that you wish to auto tune. This may be done from
the HIM, DriveExplorer or the digital I/O. Assuming you wish to select
parameter group 4, the HIM procedure for changing the active
parameter group is explained below:
1. At the HIM, press ENTER. A message similar to the following
appears:
2. Press either the up or down arrow key until the following appears:
Choose Mode
Display
Choose Mode
Program