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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.


Papers
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Journal ArticleDOI
TL;DR: Electromagnetic interference (EMI) modeling techniques for different function units in a VFD system, including induction motors, motor bearings, and rectifier-inverters, are reviewed and evaluated in terms of applied frequency range, model parameterization, and model accuracy.
Abstract: Electromagnetic interference (EMI) causes electromechanical damage to the motors and degrades the reliability of variable-frequency drive (VFD) systems. Unlike fundamental frequency components in motor drive systems, high-frequency EMI noise, coupled with the parasitic parameters of the trough system, are difficult to analyze and reduce. In this article, EMI modeling techniques for different function units in a VFD system, including induction motors, motor bearings, and rectifier-inverters, are reviewed and evaluated in terms of applied frequency range, model parameterization, and model accuracy. The EMI models for the motors are categorized based on modeling techniques and model topologies. Motor bearing and shaft models are also reviewed, and techniques that are used to eliminate bearing current are evaluated. Modeling techniques for conventional rectifier-inverter systems are also summarized. EMI noise suppression techniques, including passive filter, Wheatstone bridge balance, active filter, and optimized modulation, are reviewed and compared based on the VFD system models.

13 citations

Patent
31 May 2002
TL;DR: In this article, the main controller is attached to the variable frequency drive, which controls the speed of the motor based upon various environmental changes, such as passenger load and safety conditions.
Abstract: The present invention provides a control system designed for use in either new or existing escalators or moving walkways. The control system is comprised of a main controller and a variable frequency drive. The main controller is attached to the variable frequency drive which controls the speed of the motor based upon various environmental changes, such as passenger load and safety conditions. The control system of the present invention utilizes motions sensors, time relay switches, proximity switches and other electromechanical detectors as intelligence to detect faults and to control and vary the speed of the motor through the variable frequency drive.

13 citations

Patent
30 Apr 2008
TL;DR: In this article, a dynamic braking load analyzer that determines the proper resistance value for a braking load resistor to be used in combination with a variable frequency drive or servo-drive to accommodate the power dissipated from an induction motor when it is being reduced in speed is presented.
Abstract: A dynamic braking load analyzer that determines the proper resistance value for a dynamic braking load resistor to be used in combination with a variable frequency drive or servo-drive to accommodate the power dissipated from an induction motor when it is being reduced in speed. The analyzer includes a resistor bank having a plurality of resistors electrically coupled in parallel. Switches are provided between the resistors, and a resistor selector switch determines which resistors are switched into the resistor bank circuit. A heat sensing resistor in the resistor bank measures the heat generated by the resistors and provides a signal that is read by a heat meter. The combination of the temperature measurement and the resistance of the resistors in the circuit gives the proper braking resistance value for the deceleration of the induction motor.

13 citations

Patent
13 Jul 2012
TL;DR: In this article, a system includes a pump that is operative to move liquid out of a reservoir, and a controller that is operatively connected to the pump and the depth level sensor.
Abstract: A system includes a pump that is operative to move liquid out of a reservoir. The system also includes a depth level sensor that is operative to determine a depth level of the liquid in the reservoir, and a controller operatively connected to the depth level sensor. The system further includes a variable frequency drive operatively connected to the motor and the controller. Responsive to the determined depth level of the liquid increasing to a first level, the controller is operative to start operation of the motor. The variable frequency drive is operative to control the speed of the motor. The controller is operative to cause the variable frequency drive to output an optimum frequency that causes the motor to operate at substantially the lowest usage of energy to lower the depth level of the liquid in the reservoir from the first level to a second level.

13 citations

Journal ArticleDOI
TL;DR: In this article, a line start permanent magnet synchronous motor (LSPMSM) employing a consequent pole rotor is presented. But the rotor structure is not considered in this paper.
Abstract: This paper presents the development of line start permanent magnet synchronous motor (LSPMSM) employing a special consequent pole rotor. The proposed rotor structure uses both circumferentially magnetized spoke shape and radially magnetized arc shape magnets. The combination of spoke and arc shape is arranged to provide consequent magnetic poles. This new rotor structure improves the motor performance and consumes less magnet volume. The time-stepping finite element analysis (FEA) is used to evaluate transient and steady state performances. Extensive simulation studies are performed to establish the supremacy of proposed rotor structure over benchmarked spoke and some other known rotor structures. For experimental validation, prototypes of machine are built using (a) proposed magnet configuration, and (b) spoke type configuration having circumferentially magnetized magnets which is used as baseline motor. Rigorous experimental studies are carried out and it is observed that the proposed structure offers 4% improvement in the full load efficiency over the benchmarked spoke rotor LSPMSM yet by saving 10% magnet volume. Further, it is observed that the performance of the proposed machine is enhanced for direct online (DOL) as well as variable frequency drive (VFD) fed supply operation.

12 citations


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