C-8 Application Notes
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.
Motor Control Technology
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