Technology - Danfoss VLT DMS 300 Manual

Technology

Control principle
A variable frequency drive rectifies AC voltage
from the AC line supply into DC voltage, following
which it changes this voltage to an AC voltage
with variable amplitude and frequency.
The motor thus receives a variable voltage and
frequency, which enables infinitely variable speed
control of three-phase, standard AC motors.
1. AC line voltage
3 x 380 - 480 V AC, 50 / 60 Hz.
2. Rectifier
Three-phase rectifier bridge which rectifies AC
voltage into DC voltage.
3. Intermediate circuit
√2 x mains voltage [V].
DC voltage
4. Intermediate circuit coils
Evens out the intermediate circuit current and limits
the load on AC lines and components (electrical
transformer, cables, fuses and contactors).
5. Intermediate circuit capacitor
Evens out the intermediate circuit voltage.
6. Inverter
Converts DC voltage into a variable AC voltage
with a variable frequency.
7. Motor voltage
Variable AC voltage depending on supply voltage.
Variable frequency: 0.2 - 132 / 1 - 1000 Hz.
8. Control card
Here is the computer that controls the inverter
which generates the pulse pattern by which
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the DC voltage is converted into variable AC
voltage with a variable frequency.
MG.90.F2.22 - VLT is a registered Danfoss trademark