2.3 Technology
2.3.1 Control Principle
A frequency converter rectifies AC voltage from the mains 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.
Mains 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
DC voltage
≅ √
2 x mains voltage [V].
4.
Intermediate circuit coils
Evens out the intermediate circuit current and limits the load on mains and components (mains 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 the DC voltage is converted into variable AC voltage
with a variable frequency.
2.3.2 The Decentral Concept
The FCD 300 Adjustable speed drive is designed for decentral mounting, e.g. in the food and beverage industry, in the automotive industry, or for other
material handling applications.
With the FCD 300 it is possible to utilize the cost saving potential by placing the power electronics decentrally, and thus make the central panels obsolete
saving cost, space and effort for installation and wiring.
The unit is flexible in its mounting options for as well stand alone mounting and motor mounting. It is also possible to have the unit pre-mounted on a
Danfoss Bauer geared motor (3 in one solution). The basic design with a plugable electronic part and a flexible and “spacious” wiring box is extremely
servicefriendly and easy to change electronics without the need for unwiring.
The FCD 300 is a part of the VLT frequency converter family, which means similar funcionality, programming, and operating as the other family members.
2.3.3 FCD 300 Control Principle
A frequency converter is an electronic unit which is able to infinitely variably control the rpm of an AC motor. The frequency converter governs the motor
speed by converting the regular voltage and frequency from mains, e.g. 400 V / 50 Hz, into variable magnitudes. Today the frequency converter controlled
AC motor is a natural part of all types of automated plants.
VLT
®
Decentral FCD 300 Design Guide
2 Introduction to FCD 300
MG.90.S1.02 - VLT
®
is a registered Danfoss trademark
33
2
