Variable-frequency drive - Wikipedia, the free encyclopedia
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http://en.wikipedia.org/wiki/Variable-frequency_drive
Variable-frequency drive
From Wikipedia, the free encyclopedia
A variable-frequency drive (VFD) (also termed
adjustable-frequency drive, variable-speed drive, AC
drive, micro drive or inverter drive) is a type of
adjustable-speed drive used in electro-mechanical drive
systems to control AC motor speed and torque by
varying motor input frequency and voltage.[1][2][3][4]
VFDs are used in applications ranging from small
appliances to the largest of mine mill drives and
compressors. However, about a third of the world's
electrical energy is consumed by electric motors in
fixed-speed centrifugal pump, fan and compressor
applications and VFDs' global market penetration for all
applications is still relatively small. This highlights
especially significant energy efficiency improvement
opportunities for retrofitted and new VFD installations.
Over the last four decades, power electronics technology
has reduced VFD cost and size and improved
performance through advances in semiconductor
switching devices, drive topologies, simulation and
control techniques, and control hardware and software.
Small variable-frequency drive
VFDs are available in a number of different low and
medium voltage AC-AC and DC-AC topologies.
Contents
1 System description and operation
1.1 AC Motor
1.2 Controller
1.3 Operator interface
1.4 Drive operation
2 Benefits
2.1 Energy savings
2.2 Control performance
3 VFD types and ratings
3.1 Generic topologies
3.2 Control platforms
3.3 Load torque and power characteristics
3.4 Available power ratings
3.5 Drives by machines & detailed topologies
4 Application considerations
4.1 AC line harmonics
4.2 Long lead effects
4.3 Motor bearing currents
4.4 Dynamic braking
4.5 Regenerative drives
5 See also
6 Notes
7 References
Chassis of above VFD (cover removed)
7.11.2013 10:41