TREND NX Variable Speed Drives - Manual (Page 33)

16 • vacon TECHNICAL DATA
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4
4. TECHNICAL DATA
4.1 Introduction
Figure 4-1 presents the block diagram of the Vacon NX frequency converter. The frequency converter
mechanically consists of two units, the Power Unit and the Control Unit. Pictures of the mechanical
assemblage on pages 51 to 58.
The three-phase AC-choke (1) at the mains end together with the DC-link capacitor (2) form an LC-filter,
which, again, together with the diode bridge produce the DC-voltage supply to the IGBT Inverter Bridge (3)
block. The AC-choke also functions as a filter against High Frequency disturbances from the mains as well
as against those caused by the frequency converter to the mains. It, in addition, enhances the waveform of
the input current to the frequency converter. The entire power drawn by the frequency converter from the
mains is active power.
The IGBT Inverter Bridge produces a symmetrical, 3-phase PWM-modulated AC-voltage to the motor.
The Motor and Application Control Block is based on microprocessor software. The microprocessor
controls the motor basing on the information it receives through measurements, parameter settings,
control I/O and control keypad. The motor and application control block controls the motor control ASIC
which, in turn, calculates the IGBT positions. Gate drivers amplify these signals for driving the IGBT
inverter bridge.
Figure 4-1. Vacon NX block diagram
=
= L1
L2
L3
PE
U
V
W
3~
3~
RS 232
NK4_1
Mains Motor
Brake
Chopper*
Measure-
ments
Gate
Drivers
Motor
Control
ASIC
Motor and
Application
Control
Control
Keypad
Fan
Current
Sensors
Rectifier
IGBT
Inverter
Brake resistor*
Output
filter
Power
Supply
Control
I/O
Control
I/O
Control
I/O
Control
I/O
Control
I/O
1)
2)
3)
Integrated input module
*The brake resistor can be installed internally in sizes FR4 to FR6 (NX_2 and NX_5). In all other
frames of voltage classes NX_2 and NX_5, as well as in all frames of all other voltage classes, the
brake resistor is available as option and installed externally.
Brake chopper belongs to the standard equipment in sizes FR4 to FR6, while in greater sizes
(FR7 to FR9) it is optional.
Control
module
Power
module
Charg.res.