1.2 Additional Resources
Other resources are available to understand advanced
frequency converter functions and programming.
•
The Programming Guide provides greater detail
in how to work with parameters and many
application examples.
•
The Design Guide is intended to provide detailed
capabilities and functionality to design motor
control systems.
•
Supplemental publications and manuals are
available from Danfoss.
See http://www.danfoss.com/Products/Literature/
TeDocumentation.htm for listings.
•
Optional equipment is available that may change
some of the procedures described. Be sure to see
the instructions supplied with those options for
specific requirements.
Contact the local Danfoss supplier or go to
http://www.danfoss.com/Products/Literature/Technical
+Documentation.htm
for downloads or additional
information.
1.3 Product Overview
A frequency converter is an electronic motor controller
that converts AC mains input into a variable AC waveform
output. The frequency and voltage of the output are
regulated to control the motor speed or torque. The
frequency converter can vary the speed of the motor in
response to system feedback, such as changing
temperature or pressure for controlling fan, compressor, or
pump motors. The frequency converter can also regulate
the motor by responding to remote commands from
external controllers.
In addition, the frequency converter monitors the system
and motor status, issues warnings or alarms for fault
conditions, starts and stops the motor, optimizes energy
efficiency, and offers many more control, monitoring, and
efficiency functions. Operation and monitoring functions
are available as status indications to an outside control
system or serial communication network.
1.4 Internal Frequency Converter Controller
Functions
Below is a block diagram of the frequency converter's
internal components. See
for their functions.
Illustration 1.3 Frequency Converter Block Diagram
Area
Title
Functions
1
Mains input
•
Three-phase AC mains power
supply to the frequency
converter
2
Rectifier
•
The rectifier bridge converts
the AC input to DC current to
supply inverter power
3
DC bus
•
The frequency converter's
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 Frequency Converter Internal Components
Introduction
VLT
®
AQUA Drive
Operating Instructions
6
MG.20.M8.02 - VLT
®
is a registered Danfoss trademark
1
1
