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Variable-frequency drive<br><br>A variable-frequency drive (VFD) (also termed adjustable-frequency drive, variable-speed drive, AC drive, micro drive orinverter drive) is a type of adjustable-speed drive used in electro-mechanical drive systems to control AC motor speed andtorque by varying motor input frequency and voltage.<br>VFDs are used in applications ranging from small appliances to the largest of mine mill drives and compressors. However, around 25% of the world's electrical energy is consumed by electric motors in industrial applications, which are especially conducive for energy savings using VFDs in centrifugal load service,and VFDs' global market penetration for all applications is still relatively small. That lack of penetration highlights significant energy efficiency improvement opportunities for retrofitted and new VFD installations.<br>Over the last four decades, power electronics technology has reduced VFD cost and size and has improved performance through advances in semiconductor switching devices, drive topologies, simulation and control techniques, and control hardware and software.<br>VFDs are available in a number of different low- and medium-voltage AC-AC and DC-AC topologies.<br><br><br><br>**System description and operation : <br>A variable-frequency drive is a device used in a drive system consisting of the following three main sub-systems : <br>- AC motor,<br>- main drive controller assembly and <br>- drive/operator interface. <br>
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Variable-Frequency Drive TECHPORT SOLUTIONS provide VFD industrial training And Certification. A Variable Frequency Drive (VFD) is a type of motor controller that drives an electric motor by varying the frequency and voltage supplied to the electric motor. Other names for a VFD are variable speed drive, adjustable speed drive, adjustable frequency drive, AC drive, micro drive, and inverter. http://www.techportsolutions.in
System description and operation A variable-frequency drive is a device used in a drive system consisting of the following three main sub-systems : 1.AC motor, 2.Controller 3.Drive/Operator Interface. http://www.techportsolutions.in
Benefits of VFD Energy savings : Many fixed-speed motor load applications that are supplied direct from AC line power can save energy when they are operated at variable speed by means of VFD. Such energy cost savings are especially pronounced in variable-torque centrifugal fan and pump applications, where the load's torque and power vary with the square and cube, respectively, of the speed. Control performance : AC drives are used to bring about process and quality improvements in industrial and commercial applications' acceleration,flow, monitoring, pressure, speed, temperature, tension, and torque. http://www.techportsolutions.in
Application considerations VFD AC line harmonics : While harmonics in the PWM output can easily be filtered by carrier-frequency-related filter inductance to supply near-sinusoidal currents to the motor load,theVFD's diode-bridge rectifier converts AC line voltage to DC voltage output by super-imposing non-linear half-phase current pulses thus creating harmonic current distortion, and hence voltage distortion, of the AC line input. When the VFD loads are relatively small in comparison to the large, stiff power system available from the electric power company, the effects of VFD harmonic distortion of the AC grid can often be within acceptable limits. http://www.techportsolutions.in
Switching frequency Switching frequency foldback Noise Smoothing Long-lead effects Motor bearing currents Dynamic braking Regenerative drives http://www.techportsolutions.in
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