Rockwell Automation 20G PowerFlex 750-Series AC Drives - Manual (Page 232)

232 Rockwell Automation Publication 750-RM002B-EN-P - September 2013
Chapter 4 Motor Control
Flux Vector Control
In Flux Vector mode, the flux and torque producing currents are independently
controlled and speed is indirectly controlled by a torque reference. Alternatively,
the drive can control torque instead of speed in flux vector mode. In either case,
this mode can be operated either with or without feedback and will provide the
fastest response to load changes.
Flux Vector control is used with AC squirrel cage induction motors for high
performance. Motor data and an autotune is required for correct operation in this
mode (refer to
Autotune on page 35 for details). In Flux Vector control, the drive
takes the speed reference that is specified by the Speed Reference Selection block
and compares it to the speed feedback. The speed regulator uses Proportional
and Integral gains to adjust the torque reference for the motor. This torque
reference attempts to operate the motor at the specified speed. The torque
reference is then converted to the torque producing component of the motor
current.
This type of speed regulator produces a high bandwidth response to speed
command and load changes. Because Flux Vector controls the flux and torque
producing currents independently, a torque reference can be sent directly instead
of being generated from a speed reference via the Speed Regulator. The
independent flux control also enables flux to be reduced in order to run above
base motor speed.
Flux Vector
Torque Ref.
V mag
Voltage
Control
Inverter Motor
Speed
Reg.
Speed Freq.
Current Feedback
High Bandwidth Current Regulator
Adaptive
Controller
Slip
V ang
Speed Feedback
Autotune Parameters
Torque Ref.
Flux Reg.
Current
Reg.
Encoder