1.5 Internal Controller Functions
is a block diagram of the adjustable frequency
drive's internal components. See
for their
functions.
Figure 1.4 Adjustable Frequency Drive Block Diagram
Area
Title
Functions
1
Mains input
•
Three-phase AC line power
supply to the adjustable
frequency drive
2
Rectifier
•
The rectifier bridge converts
the AC input to DC current to
supply inverter power
3
DC bus
•
Intermediate DC bus circuit
handles the DC current
4
DC reactors
•
Filter the intermediate DC
circuit voltage
•
Prove line transient protection
•
Reduce RMS current
•
Raise the power factor
reflected back to the line
•
Reduce harmonics on the AC
input
5
Capacitor bank
•
Stores the DC power
•
Provides ride-through
protection for short power
losses
6
Inverter
•
Converts the DC into a
controlled PWM AC waveform
for a controlled variable
output to the motor
7
Output to motor
•
Regulated three-phase output
power to the motor
8
Control circuitry
•
Input power, internal
processing, output, and motor
current are monitored to
provide efficient operation
and control
•
User interface and external
commands are monitored and
performed
•
Status output and control can
be provided
Table 1.3 Adjustable Frequency Drive Internal Components
Introduction
VLT
®
HVAC Drive D-Frame
Instruction Manual
1-4
MG16D222 - VLT
®
is a registered Danfoss trademark
1
1
