Active Front End (AFE)
vacon • 21
Local contacts: http://drives.danfoss.com/danfoss-drives/local-contacts/
4
4.
A
CTIVE
F
RONT
E
ND
(AFE)
4.1
Introduction
The VACON
®
NX Active Front End is used to transfer power between the AC input and intermediate
DC circuit. The VACON
®
NX Active Front End has a two-way function. This means that when power
is transferred from the AC input to the intermediate DC circuit, the VACON
®
NX Active Front End
rectifies the alternating current and voltage. When power is transferred from the intermediate DC
circuit to the AC input, the VACON
®
NX Active Front End inverts the direct current and voltage.
The difference between VACON
®
NX Active Front End and other Front Ends is that the unit creates
low current distortion (THDI). In a typical VACON
®
NX Active Front End configuration, the desired
number of Inverters, Figure 5, are connected to the intermediate DC circuit.
The Active Front End configuration consists of the unit itself, LCL filter, pre-charging circuit, control
unit, AC fuses, main contactor (or circuit-breaker) and DC fuses, Figure 6.
Figure 5. Typical Active Front End configuration
NFE*
3
FFE*
3
2
3
INU
2
3
INU
2
3
INU
2
2
BCU
AFE*
*
alternati ve
2
2
2
11168.emf
Common DC bus
