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.

Comparison of Shunt Active Power Filter Control Strategies for Harmonic Compensation in a Paper Industrial Factory

Abstract: This paper presents the analysis and evaluates different control strategies of shunt active power filters which are used to reduce harmonic distortion created by an industrial paper factory. The model of the whole system has been carried out by Matlab/Simulink. In order to investigate the accuracy of the simulated model, harmonic analysis of simulation results has been compared with measurements from the electrical networks of a Paper Industrial Factory using harmonic analyzer. The consistency of simulation and measured results proves the accuracy of the system modeling. It also proves the validity of using Shunt Active Power Filters to reduce the harmonic distortion in the factory network. Four different control techniques, namely Unit Vector Template Generation, Instantaneous Active and Reactive theory, Synchronous Reference Frame theory and a proposed control strategy that combines the Synchronous Reference Frame and the Unit Vector Template Generation theories, have been studied. Results of each technique were satisfactory and meet the IEEE-519 Standard, However, when the source voltage is distorted the compensation capability for some control strategies is not equal.

Screw rod machine central air conditioning synchronous machine variable frequency drive system

Abstract: The utility model discloses a screw rod machine central air conditioning synchronous machine variable frequency drive system, including control system, rectifier unit, inverter unit and synchronous machine, control system is connected with rectifier unit, inverter unit respectively, and rectifier unit passes through inverter unit and is connected with synchronous machine, and control system control rectifier unit insert rectifier unit 2 and convert the direct current into, after inverter unit converts rectifier unit 4 into, offers synchronous machine with the rectifier unit 6 rectifier unit 7 machine. The utility model has the advantages of simple structure, system's weight and small, operating stability and operating efficiency are high.

Controlling Flow Rate and Fluid Level by Variable Frequency Drive Unit

Abstract: The Variable Frequency Drive (VFD) is used to control the speed of the pumpmotor to attain the desired flow rate and fluid level in a fluid system. An AC drive provides efficient flow control by varying the pump-motor speed. The comparison of energy requirements and costs in a system where a throttling device is used for flow control on a centrifugal pump with the power used when an variable frequency drive (VFD) is used to control the same flow, evidently shows potential savings. In this system, AC Motor Frequency drive and static pressure transmitter, turbine type flowmeter and Analog/Digital cards, micro-control unit and computer connection are designed specially to control flow rate, fluid flow type (turbulence or laminar) and water level at the different conditions with different PID parameters.

Using Programmable Logic Controllers to Simulate Common Motor Load Curves in Industry

Abstract: This paper addresses the need to simulate in laboratory, realistic load torque-speed curve profiles encountered in industry. Such an objective matches certain training requirements for students attending technology diploma and/or undergraduate engineering programs. The versatility of the lab equipment allowed the inscription of the motor load curves into the memory of a variable frequency drive converter (VFD, particularly of Allen-Bradley Power Flex70 type) and of a four quadrant drive (4QD, particularly of Allen-Bradley Power Flex DC type) through a Programmable Logical Controller (PLC, of Allen-Bradley type). Both converters, VFD, respectively 4QD communicated with the PLC through an Ethernet switch, and operated an induction motor (IM) and a DC generator, the last one playing the character of load emulator. Real time information about the IM and DC machine came into the PLC inputs. The system was able to simulate the "Linear", "Quadratic", and "Cubic" load models, with results verified through the "Trending" function in PLC software Studio5000. On top of successful experiments, resulted one installation manual, one user manual for the experimental stand, and several lab procedures, projected to guide future students attending engineering technology/undergraduate engineering on how to operate this experimental stand.

Efficiency of Introduction of Variable Frequency Drive

Abstract: The problem of energy conservation is currently very relevant. Analysis of the structure of electricity losses shows that 90% is consumed by electricity, the main consumer of electricity is an electric drive (about 70%), it has a great potential for energy saving. The most common in the industry is an asynchronous electric drive, most of them are unregulated. Replacing an unregulated electric drive with an adjustable one in these units can significantly save electricity, increase the life of the mechanical part of the drive and improve the quality of the adjustable process parameter. The paper provides the rationale for the introduction of a frequency-controlled electric drive to optimize technological processes in electrical complexes and systems, in particular, a complete analysis of the energy efficiency of the use of a frequency-controlled drive in pumping water supply systems is presented.