Application Notes C-9
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.
Vector Control can operate in one of two configurations:
1. Encoderless
Not to be confused with Sensorless Vector above, Encoderless Vector
based on Allen-Bradley’s patented Field Oriented Control
technology means that a feedback device is not
required. Torque
control can be achieved across a significant speed range without
feedback.
2. Closed Loop (with Encoder)
Vector Control with encoder feedback utilizes Allen-Bradley’s Force
Technology™. This industry leading technology allows the drive to
control torque over the entire speed range, including zero speed. For
those applications that require smooth torque regulation at very low
speeds or full torque at zero speed, Closed Loop Vector Control is
the answer.
Speed Regulators
Any of the PowerFlex drives, regardless of their motor control
technology (Volts/Hz, Sensorless Vector or Vector) can be set up to
regulate speed. Speed regulation and torque regulation must be separated
to understand drive operation.
The PowerFlex 70 and PowerFlex 700 with Standard Control can be
programmed to regulate speed using the slip compensation feature. Slip
compensation reacts to load changes by adjusting the drive output
frequency to maintain motor speed
. Torque production operates
independently. This feature produces speed regulation of about 0.5% of
base speed over a specified speed range (40:1 for V/Hz and 80:1 for
Sensorless Vector). These two drives do not have the capability to extend
the speed range or tighten the speed regulation below 0.5% because they
do not have connections for a feedback device.
The PowerFlex 700 with the Vector Control option can offer better speed
regulation by adding speed feedback. Using a speed feedback device
(encoder) tightens speed regulation to 0.001% of base speed and extends
the speed range to zero speed.
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