Rockwell Automation 8720MC Drives Integration Manual - Manual (Page 40)

Publication 8720MC-IN002A-EN-P — December 2002
2-8 Commissioning Your 8720MC Analog Drive
Setting the Servo Loop Parameters
Each group of servo loop parameters can have its own set of values
for mode of operation, velocity limits and torque limits. In the analog
version of the 8720MC drive, the mode of operation can be set for
either velocity or torque modes. The parameter for making this
selection for group 0 is parameter 32, “Primary Op Mode0”. The
parameter numbers are different for each of the 8 servo loop
parameter groups as (refer to Appendix C). The default mode for
parameter 32 and all 7 of the other primary operation mode
parameters is “Velocity”. If torque mode is required, use the
techniques described in Appendix B to modify this parameter. The
velocity limits should be modified to suit the application. Parameters
38 and 39, “+Velocity Limit 0” and “-Velocity Limit 0” are the velocity
limit parameters for servo loop parameter group 0.
The parameter numbers are different for each of the 8 servo loop
parameter groups as described in Appendix C. Locate these
parameters and change their values to the maximum motor speed in
rpm, as desired for the application.
The torque limits should also be modified to suit the application.
Parameters 82 and 83, “+Torque Limit 0” and “-Torque Limit 0” are the
torque limit parameters for servo loop parameter group 0. The
parameter numbers are different for each of the 8 servo loop
parameter groups as described in Appendix C. Locate these
parameters and change their values to the maximum allowable motor
torque for the application as a percentage of full-rated continuous
motor torque, as desired for the application. The drive is now ready to
auto tune the remaining servo loop parameters.
Understanding Acceleration/Deceleration Parameters
Each parameter set has an acceleration parameter and a deceleration
parameter. For parameter group 0 the acceleration parameter number
is 136 and the deceleration parameter is 137. These parameters are
used to select the maximum acceleration and deceleration rates in
radians per second squared for a given parameter set. The
acceleration and deceleration parameters are used to limit the rate of
change of velocity of the motor to a level that can be supported with
load connected. With high inertia loads it is often necessary to limit
the deceleration to prevent bus over voltage or over current trips
caused by over running loads. The values for acceleration and
deceleration are adjusted by trial and error to suit the application.