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Variable-frequency drive

About: Variable-frequency drive is a research topic. Over the lifetime, 837 publications have been published within this topic receiving 5691 citations. The topic is also known as: VFD.


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Book ChapterDOI
28 Nov 2018
TL;DR: In this paper, the authors investigate the behavior of scalar controlled AC Variable Frequency Drives for induction motors when coupled with different types of loads and show that the efficiency is lowest for square and cubic torques loads compared to linear and constant torque loads.
Abstract: In this paper, we investigate the behaviour of scalar controlled AC Variable Frequency Drives for induction motors when coupled with different types of loads. It is well known that slip is more pronounced at high speeds rather than low speeds in loads such as in pumps and fans operation because the torque load varies as the square or cube of the speed. Slip compensation in Voltage/Frequency controlled Variable Frequency Drives may work only up to a certain limit since the problem can be exacerbated by overcompensation causing low magnetisation flux of the stator and the Variable Frequency Drive becomes uncontrollable. In this research work, we investigate the behaviour of the motor and Variable Frequency Drive assembly with regards to slowly changing loads from low to high speeds. Results show that at reduced speeds for the Variable Frequency Drive and motor assembly, the efficiency is lowest for square and cubic torques loads compared to linear and constant torque loads. Highest efficiency and torque are achieved only in a restricted interval of speed. This problem therefore compels us to avoid using the Variable Frequency Drives in the Voltage/Frequency mode at low speeds for pumps and fans.

1 citations

Dissertation
03 Jun 2009
TL;DR: In this paper, the performance of double-fed induction generator (DFIG) variable speed wind turbine under network fault or under dynamic loading is studied, and the significant result of the analysis is also shown and being compared with the existing literature to validate the approach.
Abstract: The global electrical energy consumption is rising and there is a steady increase in the demand of power generation So, in addition to conventional power generation units a large no of renewable energy units are being integrated into the power system A wind electrical generation system is the most cost competitive, environmentally clean and safe out of all the renewable energy sources The recent evolution of power semiconductors and variable frequency drive technology has aided the acceptance of variable speed generation systems Slip ring induction motor in the variable speed double fed induction generator mode is largely used in wind turbine generation technology Therefore, a detailed model of induction generator is presented in the thesis Then the induction generator is operated at different operating conditions and the results are presented in the thesis A hardware set up is build up to estimate the different circuit parameter under different operating conditions Speed, torque, Active and reactive power estimation are proposed in the thesis with the help of hardware set-up Because these are the controllable parameter and they determine the machine performance So, by estimating these parameter our future aim is to manipulate those parameter and to design a closed loop controller for DFIG This study is relevant as DFIG-wind turbines are an integrated part of Distributed generation system Any abnormalities associated with grid are going to affect the system performance considerably Taking this into account, the performance of double fed induction generator (DFIG) variable speed wind turbine under network fault or under dynamic loading is studied The significant result of the analysis is also shown and being compared with the existing literature to validate the approach

1 citations

Patent
09 Mar 1999
TL;DR: In this article, a variable frequency drive (VFD) is controlled during a milking phase by a plc programmable controller and a proportional/integral (PI) controller which respond to a vacuum feedback sensor connected to the milking system.
Abstract: A vacuum control for milking systems includes a vacuum pump driven by an electric motor which is activated by a variable frequency drive (VFD). The VFD is controlled during a milking phase by plc programmable controller and a proportional/integral (PI) controller which respond to a vacuum feedback sensor connected to the milking system. The plc controller differentiates between milk and wash phases and also provides a fixed preset speed control for a washing phase for the milking system. The integrator interfaces between a milk/wash controller and the plc.

1 citations

01 Sep 1994
TL;DR: In this article, a case of EMI from a digital climate-control system of a building housing a data-processing facility was considered. And integrated barrier, filter and ground techniques were used to reduce the conducted and radiated EMI to harmless levels.
Abstract: : In recent years a significant number of digital devices and systems have been added to receiving and data-processing sites. These additions have enhanced the ability of the sites to accomplish their mission. They have also introduced new kinds of electromagnetic interference (EMI) into these sites along with accompanying performance degradation problems. In this thesis one specific case of EMI is considered. It is EMI from a digital climate-control system of a building housing a data-processing facility. The digital system generated excessive amounts of EMI. The EMI was conducted throughout the site over power and control conductors. Electromagnetic fields from EMI current flowing in these conductors coupled the EMI into other nearby conductors. Integrated barrier, filter, and ground techniques were used to reduce the conducted and radiated EMI to harmless levels. Electromagnetic interference, Electromagnetic compatibility, Barriers filters, Grounds, Variable-Frequency drive controller, Variable speed motors, EMI standards.

1 citations

OtherDOI
01 Jan 2019
TL;DR: In this article, the use of IGBT switches that are turned on and off, creating a pulse width modulated output with regulated frequency is discussed, which can achieve high propeller power a with full range of speed controls.
Abstract: The variable frequency drive (VFD) motor controller has been proven to be suitable for shipboard low voltage and medium voltage application. The variable speed electric propulsion is very popular due to the full range of speed and torque controls. The medium voltage variable speed electric propulsion can achieve high propeller power a with full range of speed controls. There are types of power switching devices used with VFDs. This chapter discusses the use of IGBT which are semiconductor switches that are turned on and off, creating a pulse width modulated output with regulated frequency. The smart ship system design concept can be embodied in “digital twin” in view of low cost computing, powerful analytical platforms of data mining, machine learning, and data networking technology. Any complex ship design and development fidelity can be achieved by using “digital twin”, so that there is no need for arbitrary simulation, costly hardware in the loop prototyping.

1 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20239
202220
202143
202084
201956
201887