Ac drives function by converting a constant ac frequency and voltage into a variable frequency and voltage. Parmenter, in energy management principles second edition, 2016. A vfd converts the 5060hz fixedfrequency and fixed. This includes that many of the possibilities of the vector variable frequency drive cannot be discovered without additional automation tools to deliver feedback to the vector variable frequency drive. A variablefrequency drive vfd is a system for controlling the rotational speed of. The preferred method of speed control for squirrelcage induction motors is to vary the frequency of the supply voltage and the system used for this purpose is known as variable frequency drives or vfd. Precharging speed torque characteristics of a drive. All acs320 drive end grounding screws are removed at the factory. Vfd working principle a variable frequency drive controls the speed, torque, and direction of an ac induction motor. Variable frequency drive basic principle of a vfd in theory the basic idea is simple, the process of transforming the line frequency to a variable frequency is basically made in two steps. It works by changing the frequency of the power supply to the motor, the motor speed being directly proportional to the supply frequency. Ac motor, main drive controller assembly, and drive operator interface. In this presentation, we will be covering variable frequency drives vfds and their theory, application, and troubleshooting.
In order to properly cover the subject, it will be broken into. Comply with all applicable national accident prevention regulations e. Drives section is in book 2 of current version of our catalog, or you can download pdf of section here. Static ac variable speed drives that were readily available were of the six step, variable voltage design. For lowvoltage lv drives, the most common method uses dctoac conversion with pulsewidth modulation pwm. Variable frequency drives ressources naturelles canada.
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. Pwm is a versatile technique because the frequency. Abb drives reference manual grounding and cabling of drive. Basic working principle behind vfds variable frequency drives components of a drive. A variable frequency drive will control the speed of doubling machine according to the load variation and thus reduces power consumption. The speed of an alternating current ac motor depends on three principle variables. According to the variable frequency drive working principle, its the electronic controller specifically designed to change the frequency of voltage supplied to the induction motor.
Saving money and developing a solid company reputation can be achieved by reducing energy costs. Variable frequency drive vfd usage has increased dramatically in hvac applications. Due to flexible control strategies, application is majorly involved in variable speed drives such as high speed and low speed hoist industrial drives etc. How a vfd or variable frequency drive works technical. This article shows the working principle of ac drive variable frequency drive, or vfd. While all variable frequency drives vfds control the speed of an ac induction motor by varying the motors supplied voltage and frequency of power, they all do not use the same designs in. Huge energy savings potential operating centrifugal fans, pumps and compressors vary frequency of electrical. Variable frequency drives vfd, aka variable speed drive vsd have been available for use with a wide range of applications for over 20 years. Vfd is a device which is used to vary the speed of a 3phase induction motor. Later, when phillipssignetics came out with a sine coded pwm chip set, sine coded pwm drives became the norm and six step variable frequency. Bgv a3 when working with energized variable frequency drives.
What are the working principles of a variable frequency drive vfd. In two positions, the voltage is zero, ie, when all the phases are connected to the same dc bus, either negative or positive. The width of the pulses is varied so that the average voltage seen by the motor is a sine wave of a given frequency. The vfds are now commonly applied to air handlers, pumps, chillers and tower fans. This is definition used in all topical discussion on this paper. Variable frequency drive operating principle whilst there are a number of variations in variable frequency drive design. Purpose of this manual the purpose of this manual is tell you the grounding and cabling principles of variable speed drive. In case of installing an centralised air conditioner in a building, one can use either vsd variable speed drive or vfd variable frequency drive. Variable speed drives vsds, also called variable frequency drives, are a valuable tool for the energy manager. The drive also regulates the output voltage in proportion to the output frequency to provide a relatively constant ratio of voltage to frequency. Other names for this are frequency converter, ac drive converter, etc. An embedded microprocessor governs the overall operation of the vfd. Other names for a vfd are variable speed drive, adjustable speed drive, adjustable frequency drive, ac drive, microdrive, and inverter. Ac and dc variable speed drives application considerations pdf.
Working principles of variable frequency drive vfd nisco. Variable speed drives an overview sciencedirect topics. The working principle of variable frequency drives the. Ac drive working principle variable frequency ac motor. This more generic term applies to devices that control the speed of either the motor or the equipment driven by the motor fan, pump. Variable frequency drives basic operating principles and core maintenance considerations by. Describes the functioning of vfd or variable frequency drive. Gs1 variable frequency drives tech specs gs1 drives manual faq. This manual is intended for people who are involved in variable speed drive system installations and assembly. Electronic speed controllers for ac motors usually convert the ac supply to dc using a rectifier, and then convert it back to a variable frequency, variable. Variable frequency drives vfds popular speed control devices used in industrial, commercial and residential applications.
Aka vfd, vsd, asd, drive, inverter, converter, etc. These applications include single motor driven pumps, fans and compressors, as well as highly sophisticated multi drive. Variable frequency drives basic operating principles and. Typically the vsd system consists of a threephase ac induction motor and a variable frequency. 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.
The 411 on variable frequency drives understanding the basic design and operation principles behind vfds will simplify selection, operation, and maintenance rajan battish, p. When installed in the appropriate application, variable frequency drives. An electronic converter which converts direct current dc to alternating current ac is known as an inverter. Powerxl dc1 e1 variable frequency drives installation manual. These applications include single motor driven pumps, fans and compressors, as well as highly sophisticated multi drive machines. A variable frequency drive controls the speed of an ac motor by varying the frequency supplied to the motor. Huge energy savings potential operating centrifugal fans, pumps and compressors vary frequency. A variablefrequency drive is a device used in a drive system consisting of the following three main subsystems. Pdf induction motors and variable frequency drives vfds are widely used in industry to drive. Other names for a vfd are variable speed drive, adjustable speed drive, adjustable frequency drive, ac drive. Vfds are used in applications where complete control over speed is essential.
Variable voltage variable frequency speed control of. A variable frequency drive vfd, also known as ac variable speed drive, ac variable frequency drive, vfd inverter or variable voltage variable frequency drive, is a type of motor controller that drives an electric motor by varying the frequency. A variablefrequency drive vfd or adjustablefrequency drive afd. If a drive whose emc filter is not disconnected is installed on a corner grounded tn system, the drive will be damaged. The variable frequency drive is developed to control induction motors in an automated environment.
890 1103 919 599 1008 967 783 256 1014 354 1292 1409 1404 1300 1243 920 1182 794 439 1316 28 482 1015 821 393 336 36 868 479 161 459 1166 1494 293 1429 1244 237