Rockwell Automation 1395 Digital DC Drive FRN 5-10.10/9.30 - Manual (Page 113)

Chapter 5
Functional Description
5-27
Velocity Pl Control (Circle 5)
Compares the speed reference value from the Velocity Reference Control
to the actual motor speed, from the Velocity Feedback Control. The Final
Velocity Reference (Parameter 104), is modified by KF Velocity
(Parameter 661). This parameter controls the amount of velocity reference
that will be summed with velocity feedback. This is filtered and modified
through a Proportional/Integral (PI) Control function. The proportional
gain of the PI Control is determined by the value of KP Velocity Loop
(Parameter 660). A value of 8 in Parameter 660 will provide a gain of 1.
The integral gain of the PI Control is determined by the value of KI
Velocity Loop (Parameter 659). The output of the velocity control
firmware is a torque reference, which is limited before being applied to the
torque selection block.
Process Trim (Circle 7)
Process Trim Reference (Parameter 161), and Process Trim Feedback
(Parameter 162), are summed to provide the error signal into the filter
block. Process Trim Filter Constant (Parameter 713), determines the gain
of a single pole filter used in the process trim. The output of the filter is
used as the input to the process trim P/I regulator. Process Trim KI Gain
(Parameter 715) controls the integral gain, and Process Trim KP
(Parameter 716), controls the proportional gain. The output of the PI
Control is limited by adjustable high and low limits. Process Trim Low
Limit (Parameter 717), specifies the low limit of the process trim trim
output value. Process Trim High Limit (Parameter 718), specifies the high
limit. Immediately prior to the the limit test, the output of the process trim
regulator is scaled by a gain factor. Process Trim Trim Output Gain
(Parameter 719), specifies the gain value to use. Process Trim Preload
(Parameter 714), is used to preset the integral term prior to enabling of the
process trim function. Logic Command bit 15, activates the process trim
function. Process Trim Select, (Parameter 628), contains one of three
selections for determining where the output of the process trim regulator
will be applied. Possible selections include trim velocity reference, trim
torque reference, or no use of the process trim output. If used to trim the
velocity reference, the output is summed with the velocity reference, to
produce Final Velocity Reference (Parameter 104). The sum will be
limited by Parameter 721 Proc Trim Lo Sum and Parameter 722 Proc Trim
Hi Sum. If used to trim the torque reference, the output is summed with
External Torque Command (Parameter 157), to produce an input to the
Torque Select block.