Rockwell Automation 20B PowerFlex 700 AC Drives Vector Control (v4.001 and up) - Manual (Page 120)

120 Rockwell Automation Publication 20B-UM002G-EN-P - July 2014
Appendix C Application Notes
Motor Control Technology Within the PowerFlex family there are several motor control technologies:
• Torque Producers
• Torque Controllers
• Speed Regulators
Torque Producers
Volts/Hertz
This technology follows a specific pattern of voltage and frequency output to the
motor, regardless of the motor being used. The shape of the V/Hz curve can be
controlled a limited amount, but once the shape is determined, the drive output
is fixed to those values. Given the fixed values, each motor will react based on its
own speed/torque characteristics.
This technology is good for basic centrifugal fan/pump operation and for most
multi-motor applications. Torque production is generally good.
Sensorless Vector
This technology combines the basic Volts/Hertz concept with known motor
parameters such as Rated FLA, Hp, Voltage, stator resistance and flux producing
current. Knowledge of the individual motor attached to the drive allows the drive
to adjust the output pattern to the motor and load conditions. By identifying
motor parameters, the drive can maximize the torque produced in the motor and
extend the speed range at which that torque can be produced.
This technology is excellent for applications that require a wider speed range and
applications that need maximum possible torque for breakaway, acceleration or
overload. Centrifuges, extruders, conveyors and others are candidates.
Torque Controllers
Vector
This technology differs from the two above, because it actually controls or
regulates torque. Rather than allowing the motor and load to actually determine
the amount of torque produced, Vector technology allows the drive to regulate
the torque to a defined value. By independently identifying and controlling both
flux and torque currents in the motor, true control of torque is achieved. High
bandwidth current regulators remain active with or without encoder feedback to
produce outstanding results.
This technology is excellent for those applications where torque control, rather
than mere torque production, is key to the success of the process. These include
web handling, demanding extruders and lifting applications such as hoists or
material handling.