Rockwell Automation 20A PowerFlex 70EC/700VC - Manual (Page 57)

Motor Control Modes 53
In sensorless vector control, the drive commands a specific amount of voltage to
develop flux.
Sensorless Vector w/Economizer
Economizer mode consists of the sensorless vector control with an additional
energy savings function.
When steady state speed is achieved, the economizer becomes active and
automatically adjusts the drive output voltage based on applied load. By matching
output voltage to applied load, the motor efficiency is optimized. Reduced load
commands a reduction in motor flux current. The flux current is reduced as long as
the total drive output current does not exceed 75% of motor rated current as
programmed in [Motor NP FLA], parameter 42. The flux current is not allowed to
be less than 50% of the motor flux current as programmed in [Flux Current Ref],
parameter 63. During acceleration and deceleration, the economizer is inactive and
sensorless vector motor control performs normally.
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.
Apppro
ximate Full Load Cur
ve
Apppro
ximate No Load Cur
ve
Maximum Voltage
Maximum
Frequency
Base Voltage
(Nameplate)
Base Frequency
(Nameplate)
Ir Voltage
Maximum Voltage
Maximum
Frequency Frequency
V
total
Motor Nameplate Voltage
Motor Nameplate
Frequency
Ir Voltage
0
0
Rated Flux Current
Reduced Flux Current,
minimum of 50% of Rated Flux Current
Increasing
Load