Torque Performance Modes - Allen-Bradley PowerFlex 70 Reference Manual

Torque Performance
Modes
[Torque Perf Mode] or [Motor Cntl Sel] (Vector) selects the output mode of
the drive. The choices are:
• Custom Volts/Hertz
Used in multi-motor or synchronous motor applications.
• Fan/Pump Volts/Hertz
Used for centrifugal fan/pump (variable torque) installations for
additional energy savings.
• Sensorless Vector
Used for most general constant torque applications. Provides excellent
starting, acceleration and running torque.
• Sensorless Vector w/Economizer
Used in constant torque applications that have significant "idle" time
(time spent at greatly reduced load) to offer additional energy
conservation.
The following table shows the performance differences between V/Hz and
Sensorless Vector.
Fan/Pump and
Custom V/Hz
Torque Mode with Slip Comp
Speed Regulation 0.5%
(% of base speed)
Operating Speed Range 40:1
Speed Bandwidth 10 rad/sec
Volts/Hertz
Volts/Hertz operation creates a fixed relationship between output voltage
and output frequency. The relationship can be defined in two ways.
1. Fan/Pump
When this option is chosen, the relationship is 1/X
for full frequency, full voltage is supplied and for ½1/2 rated frequency,
1/4 voltage is applied, etc. This pattern closely matches the torque
requirement of a variable torque load (centrifugal fan or pump – load
increases as speed increases) and offers the best energy savings for these
applications.
Maximum Voltage
Base Voltage
(Nameplate)
Run Boost
2. Custom
Custom Volts/Hertz allows a wide variety of patterns using linear
segments. The default configuration is a straight line from zero to rated
voltage and frequency. This is the same volts/hertz ratio that the motor

Torque Performance Modes

Flux Vector
SVC with SVC with without
Slip Comp Feedback Feedback
0.5% 0.1% 0.1%
80:1 80:1 120:1
20 rad/sec 20 rad/sec 50 rad/sec
2
. Therefore;
Base Frequency
Maximum
(Nameplate) Frequency
2-205
Flux Vector
with Feedback
0.001%
1000:1
250 rad/sec