Economizer (Auto-Economizer) 2-91
Economizer
(Auto-Economizer)
Refer to Torque Performance Modes on page 2-205.
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.
Efficiency The following chart shows typical efficiency for PWM variable frequency
drives, regardless of size. Drives are most efficient at full load and full
speed.
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
10 20 30 40 50 60 70 80 90 100
% Speed/% Load
% Efficiency
vs. Speed
vs. Load
75
80
85
90
95
100
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