Rockwell Automation 20G PowerFlex 750-Series AC Drives - Manual (Page 230)

230 Rockwell Automation Publication 750-RM002B-EN-P - September 2013
Chapter 4 Motor Control
PM and SyncRel Sensorless Vector
The algorithms operate on the knowledge that motor current is the vector sum of
the torque and flux producing components of current. Values can be entered to
identify the motor values or an autotune routine can be run to identify the motor
values (see
Autotune on page 35 ). Sensorless vector offers better torque
production and a wider speed range than V/Hz. However, it is not appropriate to
use when more than one motor is connected to the same drive.
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 P26 [Motor NP Amps]. The flux
current is not allowed to be less than 50% of the motor flux current as
programmed in P75 [Flux Current Ref ]. During acceleration and deceleration,
Elec. Freq. V Ref.
Gate
Signals
V/Hz
Voltage
Control
Inverter Motor
Current
Limit
Freq. Ref. Speed Freq.
Current
Resolver
Current Feedback
Current Feedback - Total
Torque 1 Est.
Vector
Control
V Vector
Torque 1 Est.
V/Hz Control
Maximum Voltage
Base Voltage
(Nameplate)
Ir Voltage
Break Frequency
(Nameplate)
Maximum
Frequency
Appr
oxim
ate F
ull L
oad
Curv
e
Appr
oxima
te No
Load
Curv
e