Automatic Derating; Automatic Energy Optimization; Automatic Switching Frequency Modulation; Automatic Derating For High Carrier Frequency - Danfoss VLT AutomationDrive FC 301 Series Design Manual

Product Features

4.1.8 Automatic Derating

The adjustable frequency drive constantly checks for
critical levels:
•
Critical high temperature on the control card or
heatsink
•
High motor load
•
High DC link voltage
•
Low motor speed
As a response to a critical level, the adjustable frequency
drive adjusts the switching frequency. For critical high
internal temperatures and low motor speed, the adjustable
frequency drives can also force the PWM pattern to
SFAVM.
NOTICE!
The automatic derating is different when 14-55 Output
Filter is set to [2] Sine-Wave Filter Fixed.

4.1.9 Automatic Energy Optimization

Automatic energy optimization (AEO) directs the adjustable
frequency drive to continuously monitor the load on the
motor and adjust the output voltage to maximize
efficiency. Under light load, the voltage is reduced and the
motor current is minimized. The motor benefits from
increased efficiency, reduced heating, and quieter
operation. There is no need to select a V/Hz curve because
the adjustable frequency drive automatically adjusts motor
voltage.
4.1.10 Automatic Switching Frequency
Modulation
The adjustable frequency drive generates short electrical
pulses to form an AC wave pattern. The carrier frequency
is the rate of these pulses. A low carrier frequency (slow
pulsing rate) causes noise in the motor, making a higher
carrier frequency preferable. A high carrier frequency,
however, generates heat in the adjustable frequency drive
which can limit the amount of current available to the
motor. The use of insulated gate bi-polar transistors (IGBT)
means very high-speed switching.
MG33BF22
Design Guide
Automatic switching frequency modulation regulates these
conditions automatically to provide the highest carrier
frequency without overheating the adjustable frequency
drive. By providing a regulated high carrier frequency, it
quiets motor operating noise at slow speeds when audible
noise control is critical, and produces full output power to
the motor when the demand requires.
4.1.11 Automatic Derating for High Carrier
The adjustable frequency drive is designed for continuous,
full load operation at carrier frequencies between 3.0 and
4.5 kHz. A carrier frequency higher than 4.5 kHz generates
increased heat in the adjustable frequency drive and
requires the output current to be derated.
An automatic feature of the adjustable frequency drive is
load-dependent carrier frequency control. This feature
allows the motor to benefit from as high a carrier
frequency as the load permits.

4.1.12 Power Fluctuation Performance

The adjustable frequency drive withstands line power
fluctuations such as transients, momentary dropouts, short
voltage drops and surges. The adjustable frequency drive
automatically compensates for input voltages ±10% from
the nominal to provide full rated motor voltage and
torque. With auto restart selected, the adjustable frequency
drive automatically powers up after a voltage trip. And
with flying start, the adjustable frequency drive
synchronizes to motor rotation prior to start.

4.1.13 Resonance Damping

High frequency motor resonance noise can be eliminated
through the use of resonance damping. Automatic or
manually selected frequency damping is available.

4.1.14 Temperature-controlled Fans

The internal cooling fans are temperature controlled by
sensors in the adjustable frequency drive. The cooling fan
often is not running during low load operation or when in
sleep mode or standby. This reduces noise, increases
efficiency, and extends the operating life of the fan.
Rev. 2014-04-04 All rights reserved.
Frequency
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