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Karthikeyan J.,Velammal College of Engineering and Technology | Dhana Sekaran R.,Syed Ammal Engineering College
International Journal of Electrical Power and Energy Systems | Year: 2011

The objective of the paper is to build a simple current controlled modulation technique for brushless dc motors. In electric traction and most other applications, a wide range of speed and torque control of the electric motor is required. The dc machine fulfills these requirements, but it requires constant maintenance. In the brushless permanent magnet motors, they do not have brushes and so there will be lesser maintenance. Brushless dc motors are widely used in applications which require wide range of speed and torque control because of its low inertia, fast response, high reliability and less maintenance. This current controlled technique is based on the generation of quasi-square wave currents using only one controller for the three phases. The current control strategy uses a triangular carrier for the power transistors which is simpler and more accurate than any other options. The advantages of this technique are: (a) The stator currents are completely characterized by their maximum amplitude. (b) The three phases are controlled with the same dc component, and then the phase currents are kept at exactly the same magnitude Imax. (c) The dc link current measurement is not required. (d) Phase currents are kept balanced and phase over currents are eliminated. © 2011 Elsevier Ltd. All rights reserved.

Karpagam N.,Velammal College of Engineering and Technology
International Journal of Applied Engineering Research | Year: 2015

Power quality is of major concern in the power distribution systems. The increase in use of sensitive and susceptive electronic and computing equipments and other non linear loads affects the quality of power delivered which leads to severe economical impacts on both utilities and customers in distribution system. The application of custom power devices offers fast response and reliability to the electric utilities. The Distribution Static synchronous compensator (D-STATCOM) which has been emerging as a promising custom power device is selected in this work for the mitigation of voltage sag. The D-STATCOM with a suitable control strategy is capable of mitigating the voltage sag in a very fast manner and this feature of phase shift controlled D-STATCOM can be exploited to improve the power quality. Three different control strategies namely PI Controller, Fuzzy Logic Controller, Fuzzy-PI Controller have been developed for phase shift controlled D-STATCOM to mitigate the voltage sag. Proposed controllers of D-STATCOM are implemented under MATLAB/SIMULNK environment. The effectiveness of the control schemes with immediate voltage generation to mitigate the voltage sag in three phase system due to the system faults is proved with the comparative assessment of the graphical results using MATLAB/SIMULINK software. © Research India Publications.

Narendrakumar A.,Velammal College of Engineering and Technology | Thygarajah K.,Anna University
International Review on Computers and Software | Year: 2012

The proposed system utilizes the concept of multi hop communication in wireless Sensor Networks(WSNs). On the other hand, the single hop communication leads to more power dissipation in the nodes at the time of transmitting sensed data. The proposed system rectifies the above mentioned problem with the multi hop communication among the finite number of nodes to determine the distance for transferring information from source node to base station using the Fuzzy logical method. In this paper the proposed scheme a Fuzzy based High Quality Link Set Routing (FHQLSR) which selects the high quality level of relay node and evaluates the quality of link in each node by using RNP and ETX parameters. Our proposed method shows that FHQLSR improves the overall reliability, scalability and stability of the network. In a nutshell, the multi hop communication leads the better solution for saving the transmission energy in the wireless environment. © 2012 Praise Worthy Prize S.r.l. - All rights reserved.

Sundaramoorthy S.,Velammal College of Engineering and Technology | Shantharajah S.P.,Anna University
Journal of Web Engineering | Year: 2014

Data Mining involves discovery of required potentially qualified content from a heavy collection of heterogeneous data sources. Two decades passed, still it remains the interested area for researchers. It has become a flexible platform for mining engineers to analyse and visualize the hidden relationships among the data sources. Association rules have a strong place in representing those relationships by framing suitable rules. It has two powerful parameters namely support and confidence which helps to carry out framing of such rules. Frequent itemset mining is also termed to be frequent pattern mining. When the combination of items increases rapidly, we term it to be a pattern. The ultimate goal is to design rules over such frequent patterns in an effective manner i.e in terms of time co mplexity and space complexity. The count of evolutionary algorithms to achieve this goal is increasing day by day. Bio Inspired algorithms holds a strong place in machine learning, mining, evolutionary computing and so on. Ant Colony Algorithm is one such algorithm which is designed based on behaviour of biological inspired ants. This algorithm is adopted for its characteristic of parallel search and dynamic memory allocation. It works comparatively faster than basic Apriori algorithm, AIS, FP Growth algorithm. The two major parameters of this algorithm are pheromone updating rule and transition probability. The basic ant colony algorithm is improved by modifying the pheromone updating rule in such way to reduce multiple scan over data storage and reduced count of candidate sets. The proposed approach was tested using MATLAB along with WEKA toolkit. The experimental results prove that the stigmeric communication of improved ant colony algorithm helps in mining the frequent items faster and effectively than the above stated existing algorithms. © Rinton Press.

Gavara M.,Indian Institute of Science | Kanna P.R.,Velammal College of Engineering and Technology
International Communications in Heat and Mass Transfer | Year: 2012

Laminar natural convection between two coaxial vertical rectangular cylinders is numerically studied in this work. The outer cylinder is connected with vertical rectangular inlet and outlet pipes. The inner cylinder dissipates volumetric heat. The fluid flow and heat transfer characteristics between the cylinders are analyzed in detail for various Grashof numbers. The heat transfer rates on the individual faces of the inner cylinder are reported. The bottom face of the inner cylinder is found to associate with much higher heat rates than those of the other faces. The average Nusselt number on bottom face is more than 2.5 times of the Nusselt number averaged on all the faces. At a given elevation, local Nusselt number on the inner cylinder faces increases towards cylinder edges. The effect of thermal condition of the walls of outer cylinder, inlet and outlet on the natural convection is analyzed. The thermal condition shows strong qualitative and quantitative impact on the fluid flow and heat transfer. The variation of induced flow rate, dimensionless maximum temperature and average Nusselt numbers with Grashof number is studied. Correlations for dimensionless buoyancy-induced mass flow rate and temperature maximum are presented. © 2012 Elsevier Ltd.

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