Rockwell Automation 20G PowerFlex 750-Series AC Drives - Manual (Page 262)

262 Rockwell Automation Publication 750-RM002B-EN-P - September 2013
Chapter 4 Motor Control
Torque Reference The Torque Reference is a reference value in percent that represents the rated
torque development capability of the motor. During the autotune process,
measurements are made to determine the motor equivalent circuit including
connected impedance from drive terminals to the motor. Based on entered motor
nameplate information and autotune results, the Torque Reference is established
as 100% or 1 PU equal to the rated N•m (lb•ft) torque development capability
of the motor at Full Load ampere rating within ±5% without encoder feedback,
possibly within ±2% with encoder feedback.
True Torque control at the motor shaft can only occur when P35 [Motor Ctrl
Mode] is configured for one of the Flux Vector control mode choices. Likewise,
Torque Reference parameters are only active when Flux Vector control modes in
P35 [Motor Ctrl Mode], options 3 “Induction FV,” 6 “PM FV,” and 10 “IPM FV.”
Internal Torque Reference Source
The inherent Torque Reference source (default setting in any of the applicable
FV Control modes only) is the output from the Speed Regulator parameter,
P660 [SReg Output] in percent. As it passes through trimming and limiting
functions, it ultimately becomes a commanding torque reference, P690 [Limited
Trq Ref ], and an input to and for the inverter Current control to output voltage
and frequency to the motor and regulate torque producing vector of current
accordingly. Consequently, the motor develops torque as necessary to aid the
Speed Regulator to maintain minimal speed error between commanded speed
and speed feedback.