Other names for a vfd are variable speed drive, adjustable speed drive, adjustable frequency drive, ac drive, microdrive, and inverter. This paper covers what a variable frequency drive vfd is, the different types of vfds, their functions, and their benefits. Variable frequency drives vfds popular speed control devices used in industrial, commercial and residential applications. Firstly threephase induction motor drive system is simulated in various modes using matlabxilinx, then. What time did this occur, has it previously tripped at this time or process point. Oct 03, 2016 the variable frequency drive converts this line power into a pulsed output voltage that duplicates varying alternating current to a desired frequency speed. Understanding variable frequency drives learn about the various types of vfds, and what their purpose and advantages are. Eu council directives and adjustable speed electrical. Each part of a variable frequency drive has the following function.
Frequency drive vfd technology to assist in the effective. A converter is a device to create the dc from the ac power supply. Ac drive operating, frequency attained, non zero speed, base block, fault. The variable frequency drive industry is growing rapidly, and it is now more important than ever for technicians and maintenance personnel to keep vfd installations running smoothly. Power ratings up to 90kw variable torque see section 3. These applications include single motor driven pumps, fans and compressors, as well as highly sophisticated multi drive machines. Siemens standard drives application handbook martin brown. Part of the electricians technical reference series, this field guide is ideal for gaining access to information about variable frequency drives, including how. Hitachis sj300 series variable frequency drive delivers full feature performance across a wider range of demanding applications requiring high starting torque and functional versatility.
An inverter, in general, is a device that converts dc power to ac power. Variable speed and flow capability with standard induction motor. Variable frequency drives troubleshooting larry stanley, regional sales engineer, january 2014. The figure below shows how the variablefrequency drive. Variable frequency operation hence the speed of the motor depends on the applied frequency, as well as the winding arrangement, and a little on the load. This paper will present the theory to calculate such effects. Therefore in order to control the motor speed it is necessary to control the frequency of the supply. Also covered are issues related to vfds, some solutions to vfd issues, and how vfds can. The most popular type is the 3phase, squirrelcage ac induction motor. Voltshertz control is a basic control method, providing a variable frequency drive for applications like fan and pump. With this electric drive tutorial youll learn how does a variable speed drive work vfd drive working principle, and other. To understand the answer to this question we have to understand that the basic function of a variable speed drive vsd is to control the flow of energy from the mains to the process. Variable speed drives an overview sciencedirect topics. Ac drives are used to drive the ac motor especially three phase induction motors because these are predominant over other motors in most of the industries.
They all operate on the same basic variable frequency drive theory. The vfds are now commonly applied to air handlers, pumps, chillers and tower fans. Book 2 of current version of our catalog, or you can download pdf of section here. A variable frequency drives used in a drivesystem consisting of the following three mainsubsystems. The ac electric motor used in a vfd system is usually a threephase induction motor. In standard handbook of petroleum and natural gas engineering third edition, 2016. Pdf power electronics and variable frequency drives. There are a lot of tradeoffs in the different designs and depending on the goals and preferences of the. The term inverter and variablefrequency drive are related and somewhat interchangeable. Vfd 101 intro lesson variable frequency drives vfd fundamentals april 04. This program will help enhance customers product competency, troubleshooting skills, and safe operations through self. Power electronics and variable frequency drives technology and.
See the basic principle with the singlephase ac as the simplest example. One component defines the magnetic flux of the motor, the other the torque. Ac motor, main drive controller assembly, and drive operator interface. Huge energy savings potential operating centrifugal fans, pumps and compressors vary frequency of electrical. Vector control, also called fieldoriented control foc, is a variable frequency drive vfd control method in which the stator currents of a threephase ac electric motor are identified as two orthogonal components that can be visualized with a vector. This variable frequency drive basics, is a vfd basics industrial drive training online certificate course. The variablefrequency drive training system is a stateoftheart training system specifically designed to introduce students to the basic principles of variablefrequency drives vfds. Guide to variable speed drives describes basics of different. Protection from overload currents safe acceleration 5. If the frequency is reduced, the voltage must be reduced or the magnetic flux will. Vfd is shorted for variable frequency drive also known as ac drives and inverters thats used to make an ac motor working in variable speed among other parameters.
Control method there are three basic methods to control a variable frequency drive. These machines had limited functions, providing the basics of speed control and soft start and stop. Abstract variable speed drive technology has advanced dramatically in the last 10 years with the advent of new power devices and magnetic materials. What is the drive reporting in the form of fault messages. Variable voltage variable frequency speed control of. Variable frequency drives ressources naturelles canada. This has given rise to substantial confusion by users and specifiers of variable speed drive equipment. Vfd drives were first introduced in 1983, and the insulated gate bipolar transistor has in the past 20 years become the standard for vfd drives as an inverter switching device.
Variable voltage variable frequency control of threephase induction motor in closed loop is the significant feature of the thesis work. This is definition used in all topical discussion on this paper. Some types of singlephase motors or synchronous motors can be advantageous. 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. Understanding the basic principles behind vfd operation requires understanding the three basic sections of the vfd. The basic configuration of a variable frequency drive is as follows. A better understanding of vfds will lead to improved application and selection of both equipment and hvac systems.
New current regulation principle for power convertors. There are four basic types of control for ac drives today. This program will help enhance customers product competency, troubleshooting skills, and safe operations through selfguided, elearning and instructor led training. Variable frequency vfd5 baseemitter signal input pins dc link positive terminal c 1 dc link negative terminal e 2 phase output terminal e 1c 2 module mounting holes heat sink on module back plane module schematic diagram variable frequency drive vfd output module shown below is a typical medium voltage vfd transistorized output module. A variable frequency drive is a device used in a drive system consisting of the following three main subsystems. Refer to the technical manual for the individual machine for. A basic vfd system generally consists of an ac motor, a controller, and an operator interface. Drive type and motor control algorithm will effect how a vfd trips on opl acs550 only trips in vector mode. Adaptive basic autotuning autotuning to perform sensorless vector control can now be easily done both online and offline. In industrial terms, ac drive is also called as variable frequency drive vfd, variable speed drive vsd, or adjustable speed drive asd. It provides a comprehensive, highquality, and costeffective solution to rapidly build student knowledge in vfds and their motor applications.
Variable speed drives vsds, also called variable frequency drives, are a valuable tool for. An electronic drive for an ac motor controls the motors speed by varying the frequency of the power sent to the motor. Variable frequency drives vfd, aka variable speed drive vsd have been available for use with a wide range of applications for over 20 years. Add to that the difficulty in evaluating efficiency and power factor and the. The basic principle of operation is for a rotating magnetic field to act upon a rotor winding in order to develop mechanical torque. Vfd fundamentals copyright 2003 kilowatt classroom, llc. These are volts per hertz, sensorless vector control, flux vector control, and field oriented control. Each variable frequency drive basics coursetraining student will receive a detailed vfd specification and check list to use to ensure that all their vfd issues are. Mechanical, electrical, and fluid power adjustable speed drives are available. Download it once and read it on your kindle device, pc, phones or tablets.
This is possible with using variable frequency drives. Vfds and motor control training the electricity forum. Aug 21, 2017 this elearning module provides a basic understanding of variable frequency drives. Variable frequency drive, operation and application of variable. A variable frequency drive, also called frequency inverter, adjustable speed drive, the basic working principle is adjusting the electrical supply to an ac motor with a corresponding frequency and voltage change in the motors speed and torque output. Each participant will receive a dvd with dozens of articles and papers on vfd and motor data as well as the full coloured slide presentation for printing as required. Variable frequency drive vfd usage has increased dramatically in hvac applications. Aug 11, 2015 understanding variable frequency drives, part i erik arfalk aug 11, 2015 the following is an excerpt from understanding variable frequency drives and appropriate applications, a whitepaper by steve bruno, product marketing manager, oilinjected screw compressors 30kw 90kw. Thirty years ago when we were first seeing 30 hp variable frequency drive vfd the size of a refrigerator and now the size of a brief case, and there was no such thing as a severe duty motor, and it was an absolute taboo to use a variable frequency drive vfd for variable speed.
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