Control Principle; Aeo - Automatic Energy Optimization - Danfoss VLT 8000 AQUA series Operating Instructions Manual

Control principle

A frequency converter rectifies AC voltage from
mains into DC voltage, after which this DC
voltage is converted into a AC current with a
variable amplitude and frequency.
1. Mains voltage
3 x 200 - 240 V AC, 50 / 60 Hz.
3 x 380 - 480 V AC, 50 / 60 Hz.
3 x 525 - 600 V AC, 50 / 60 Hz.
3 x 525 - 690 V AC, 50 / 60 Hz.
2. Rectifier
A three-phase rectifier bridge that rectifies AC
current into DC current.
3. Intermediate circuit
DC voltage = 1.35 x mains voltage [V].
4. Intermediate circuit coils
Even out the intermediate circuit voltage and reduce
the harmonic current feedback to the mains supply.

AEO - Automatic Energy Optimization

Normally, the U/f characteristics have to be set on the
basis of the expected load at different frequencies.
However, knowing the load at a given frequency in an
installation is often a problem. This problem can be
solved by using a VLT 8000 AQUA with its integral
Automatic Energy Optimization (AEO), which ensures
optimum energy utilization. All VLT 8000 AQUA units
feature this function as a factory setting, i.e. it is
not necessary to adjust the frequency converter U/f
ratio in order to obtain maximum energy savings.
In other frequency converters, the given load and
voltage/frequency ratio (U/f) must be assessed to carry
out correct setting of the frequency converter.
Using Automatic Energy Optimization (AEO), you
no longer need to calculate or assess the system
characteristics of the installation, since Danfoss VLT
8000 AQUA units guarantee optimum, load-dependent
energy consumption by the motor at all times.
The figure on the right illustrates the working
range of the AEO function, within which energy
optimization is enabled.
10
®
VLT 8000 AQUA
The motor is thus supplied with variable voltage and
frequency, which enables infinitely variable speed
control of three-phased, standard AC motors.
5. Intermediate circuit capacitors
Even out the intermediate circuit voltage.
6. Inverter
Converts DC voltage into variable AC voltage
with a variable frequency.
7. Motor voltage
Variable AC voltage, 0-100% of mains supply voltage.
8. Control card
This is where to find the computer that controls
the inverter which generates the pulse pattern by
which the DC voltage is converted into variable
AC voltage with a variable frequency.
If the AEO function has been selected in parameter 101,
Torque characteristics, this function will be constantly
active. If there is a major deviation from the optimum U/f
ratio, the frequency converter will quickly adjust itself.
Advantages of the AEO function
• Automatic energy optimization
• Compensation if an oversize motor is used
• AEO matches operations to daily or
seasonal fluctuations
MG.83.A2.02 - VLT is a registered Danfoss trademark