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28,451 Article Results

Constant Frequency Torque Controller for DTC with Multilevel Inverter of Induction Machines

10.11591/ijpeds.v7.i1.pp28-44
Norjulia Mohamad Nordin , Naziha Ahmad Azli , Nik Rumzi Nik Idris , Nur Huda Ramlan , Tole Sutikno
Direct Torque Control using multilevel inverter (DTC-MLI) with hysteresis controller suffers from high torque and flux ripple and variable switching frequency. In this paper, a constant frequency torque controller is proposed to enhance the DTC-MLI performance. The operational concepts of the constant switching frequency torque controller of a DTC-MLI system followed by the simulation results and analysis are presented. The proposed system significantly improves the DTC drive in terms of dynamic performance, smaller torque and flux ripple, and retain a constant switching frequency.
Volume: 7
Issue: 1
Page: 28-44
Publish at: 2016-03-01

Design of Three-Phase Three-Switch Buck-Type Rectifier for Pre-Charging Application

10.11591/ijpeds.v7.i1.pp124-133
Anandh S , Vijayan S , Paramasivam Paramasivam
The main objective of a pre-charging circuit in variable frequency drives is to pre-charge the DC-bus capacitor without any voltage and current overshoot within the specified time. In exisiting variable frequency drives seperte pre-charging circuits (or) thyristor bridges were used due to this drives power density, cost becomes high and control technique becomes complex.  This paper presents about the design of three-phase three-switch buck-type rectifier for pre-charging application used in variable frequency drives which elimates the disadvantages of existing techniques. In this paper we will discuss about design procedure of pre-charging circuit of an 800KW converter with dc-link output voltage of 775V at an input ac voltage of 550V, 60Hz, selection of power and passive components, voltage and current stress of power transistors. In the final this paper discusses about loss distribution of the components and comparison of new converter technique with existing pre-charging techniques.
Volume: 7
Issue: 1
Page: 124-133
Publish at: 2016-03-01

A Shunt Active Power Filter for 12 Pulse Converter Using Source Current Detection Approach

10.11591/ijpeds.v7.i1.pp225-234
Rajesh T , Nirmalkumar A
A shunt Active Power Filter (APF) with current detection at the source side is considered as a closed-loop system from the view of the whole power distribution system, which is expected with better harmonics filtering performance compared with conventional current detection methods such as load current detection and open loop control.  This paper introduces an efficient source current detection method (direct) control scheme to mitigate the grid current harmonics generated by the twelve pulse converter.  The proposed system uses Control Rectifier (12 –pulse converter) which efficiently regulates the DC voltage by varying the angle of each 6 pulse converter. Moreover, the proposed system uses three winding transformer which eliminates the harmonics during equal angles switching at each six pulse converter which in turn simplifies the operation of the SAPF. The proposed system is simulated in MATLAB SIMULINK to evaluate the performance of the proposed system.
Volume: 7
Issue: 1
Page: 225-234
Publish at: 2016-03-01

Enhanced Derivative-Free Conjugate Gradient Method for Solving Symmetric Nonlinear Equations

10.11591/ijaas.v5.i1.pp50-57
Jamilu Sabi'u
In this article, an enhanced conjugate gradient approach for solving symmetric nonlinear equations is propose without computing the Jacobian matrix. This approach is completely derivative and matrix free. Using classical assumptions the proposed method has global convergence with nonmonotone line search. Some reported numerical results shows the approach is promising. 
Volume: 5
Issue: 1
Page: 50-57
Publish at: 2016-03-01

Effect of Novel Nanocomposite Materials for Enhancing Performance of Thin Film Transistor TFT Model

10.11591/ijaas.v5.i1.pp1-12
Youssef Ahmed Mobarak , Moamen Atef
The potential impact of high permittivity gate dielectrics on thin film transistors short channel and circuit performance has been studied using highly accurate analytical models. In addition, the gate-to-channel capacitance and parasitic fringe capacitances have been extracted. The suggested model in this paper has been increased the surface potential and decreased the threshold voltage, whenever the conventional silicon dioxide gate dielectric is replaced by high-K gate dielectric novel nanocomposite PVP/La2O3Kox=25. Also, it has been investigated that a decrease in parasitic outer fringe capacitance and gate-to-channel capacitance, whenever the conventional silicon nitride is replaced by low-K gate sidewall spacer dielectric novel nanocomposite PTFE/SiO2Ksp=2.9. Finally, it has been demonstrated that using low-K gate sidewalls with high-K gate insulators can be decreased the gate fringing field and threshold voltage. In addition, fabrication of nanocomposites from polymers and nano-oxide particles found to have potential candidates for using it in a wide range of applications in low cost due to low process temperature of these nanocomposites materials.
Volume: 5
Issue: 1
Page: 1-12
Publish at: 2016-03-01

Methods of Assess the Impact of Technological Variables Complex Spatial-Distributed Systems on Costs

10.11591/ijaas.v5.i1.pp45-49
Korneev A.M. , Shmyrin A.M. , Lavrukhina T.V. , Abdullakh L.S.
The paper considers the method of calculating costs, taking into account the effect of technological parameters; the model of forecasting of costs of production resources based on the matrix of costs are described; the methods of assess the impact of parameters of complex spatial-distributed systems on costs are presented.
Volume: 5
Issue: 1
Page: 45-49
Publish at: 2016-03-01

Experimental Investigations of the Self-Controlled Synchronous Motor Connected to a Three-Phase Line Commutated SCR Inverter

10.11591/ijpeds.v7.i1.pp1-6
Tapan Kumar Chakraborty
This paper concerns the experimental investigations of the three-phase line commutated SCR inverter fed synchronous motor.  The fabricated system consists of a line-commuted inverter, a three-phase synchronous motor with the excitation winding connected in series to the inverter input, a terminal voltage sensor and a gate-pulse generating circuit. The firing pulses for SCRs of the inverter are generated by the microprocessor in proper sequence with the help of synchronizing signal derived from the terminal voltages of the synchronous machine. The steady state performance characteristics are obtained experimentally using the fabricated system. The experimental results show that a three-phase synchronous motor supplied by a line commutated inverter with the excitation winding connected in series to the dc link provide  excellent characteristics of the conventional dc series motor. 
Volume: 7
Issue: 1
Page: 1-6
Publish at: 2016-03-01

Performance Analysis of (Bi2Te3-PbTe) Hybrid Thermoelectric Generator

10.11591/ijaas.v5.i1.pp32-44
Anitha Angeline A , Jayakumar J
The performance of (Bi2Te3-PbTe) hybrid thermoelectric generator (TEG) composed of n-type Bismuth Telluride and p-type Lead Telluride semiconductor materials is presented in this paper.  The effect of different performance parameters such as output voltage, output current, output power, maximum power output, open circuit voltage, Seebeck co-efficient, electrical resistance, thermal conductance, figure of merit, efficiency, heat absorbed and heat removed based on maximum conversion and power efficiency have been theoretically analyzed by varying the hot side temperature of the hybrid thermoelectric generator up to 350oC and by varying the cold side temperature from 30oC to 150oC. The results showed that a maximum power output of 21.7 W has been obtained with the use of one hybrid thermoelectric module for a temperature difference of 320oC between the hot and cold side of the thermoelectric generator at matched load resistance. The figure of merit was found to be around 1.28 which makes its usage possible in the intermediate temperature (250oC to 350oC) applications such as heating of Biomass waste, heat from Biomass cook stoves or waste heat recovery etc. It is also observed that the hybrid thermoelectric generator offers superior performance over 250oC of the hot side temperature, compared to standard Bi2Te3 modules.
Volume: 5
Issue: 1
Page: 32-44
Publish at: 2016-03-01

VHDL Implementation of Capacitor Voltage Balancing Control with Level-Shifted PWM for Modular Multilevel Converter

10.11591/ijpeds.v7.i1.pp94-106
Chuen Ling Toh , Lars Einar Norum
Power electronics converters are a key component in high voltage direct current (HVDC) power transmission. The modular multilevel converter (MMC) is one of the latest topologies to be proposed for this application. An MMC generates multilevel output voltage waveforms which reduces the harmonics contents significantly. This paper presents a VHDL implementation of the capacitor voltage balancing control and level-shifted pulse width modulation (LSPWM) for MMC. The objective is to minimize the processing time with minimum gate counts. The design details are fully described and validated experimentally. An experiment is conducted on a small scale MMC prototype with two units of power cells on each arm. The test results are enclosed and discussed.
Volume: 7
Issue: 1
Page: 94-106
Publish at: 2016-03-01

Comparison of Various Levels of Parallel Multilevel Active Filter Using NPC Multilevel Inverter

10.11591/ijaas.v5.i1.pp21-31
Farouk Hadj Benali , Fouad Azzouz
This paper puts forward the technique of reference signal generation of the reactive instantaneous power and the technique of the SPWM control signal generation of the multilevel active filter.  A comparison between the source currents before and after filtering is made. Then a comparison between the different source currents of different multilevel active filters. The subjects of comparison are the total harmonic distortions (THD) of the source current. The obtained simulation results have proved that the filtering quality is improved when increasing the active filter levels. Simulations are carried out by PSIM program.
Volume: 5
Issue: 1
Page: 21-31
Publish at: 2016-03-01

Novel Single Phase Full Bridge Inverter Formed by Floating Capacitors

10.11591/ijpeds.v7.i1.pp193-201
Prathap Reddy Bhimireddy , Sreekanth Reddy Kondreddy , Samba Siva Reddy Beduduri
In this paper, a new single-phase bridge inverter is described which can generate a more steps of voltage levels with reduced number of switches, gate driver circuits and diodes as compare to normal multilevel inverter. Another feature of this inverter is its ability to prodeuce the voltages from a single dc-link power supply which enables back-to-back operation of converter. The proposed method with more number of levels can improve power quality, lower switching losses and produce high quality voltage waveforms. Moreover at all load power factors the proposed method can be operated.The research of the model is done by means of computer simulation with the software MATLAB/SIMULINK. This topology has very low common mode voltage variation and dv/dt stress. Also this inverter is help full for reactive power compensation.
Volume: 7
Issue: 1
Page: 193-201
Publish at: 2016-03-01

An Optimal Replenishment Policy for the EPQ Model with Permissible Delay in Payments

10.11591/ijaas.v5.i1.pp13-20
Shih-Ming Ou , Kuo-Kuang Chang
Most of the past researches on economic replenishment quantity did not consider the trade credit period. In practice, however, companies in Taiwan have shown that taking the trade credit period into account when they are making inventory decisions decreases costs substantially. The aim of this paper is to develop an inventory model that incorporates a delay in payments to minimize the total inventory-relevant cost. The optimal replenishment policy of the proposed model is identified by utilizing the global optimum conditions and non-constrained quadratic nonlinear programming. The results show that the existence of global optimal inventory cycle under the condition of total cost function is convex. Accordingly, the proposed model can assist managers in effectively addressing EPQ issue under competitive market.
Volume: 5
Issue: 1
Page: 13-20
Publish at: 2016-03-01

The Retention of Women in Science, Technology, Engineering, and Mathematics: A Framework for Persistence

10.11591/ijere.v5i1.4515
Jeffry L. White , G.H. Massiha
Women make up 47% of the total U.S. workforce, but are less represented in engineering, computer sciences, and the physical sciences. In addition, race and ethnicity are salient factors and minority women comprise fewer than 1 in 10 scientist or engineer. In this paper, a review of the literature is under taken that explores the many challenges women encounter when pursing a career in the sciences. It includes a review of the national landscape and discussion of the guiding general retention theories. Finally it proposes a conceptual framework for persistence and proffers a number of research questions designed to delve deeper into the under representation phenomenon.
Volume: 5
Issue: 1
Page: 1-8
Publish at: 2016-03-01

The Roles of Teachers’ Work Motivation and Teachers’ Job Satisfaction in the Organizational Commitment in Extraordinary Schools

10.11591/ijere.v5i1.4520
Fatwa Tentama , Dessy Pranungsari
Teachers’ work motivation and teachers’ job satisfaction are the factors influencing the organizational commitment. This research is aimed to empirically examine the roles of teachers’ work motivation and teachers’ job satisfaction in the commitment of the organization in extraordinary schools. The subjects of the research are the teachers in Extraordinary School 1 Bantul Yogyakarta. The sample was taken by employing non-randomized technique. The scales of work motivation, job satisfaction and organizational commitment are used in collecting the data. The data were analyzed by using multiple linear regression technique. The results of the research show that 1) simultaneously, teachers’ work motivation and teachers’ job satisfaction are highly significant positive correlated with organizational commitment, by reaching the score of Rx1x2v=0,621 with the probability p=0,002 (p<0,01); 2) teachers’ work motivation are highly significant correlated with the organizational commitment, by reaching the score of (rx1v))=0,614 and the probability p=0,000 (p<0,01); 3) teachers’ job satisfaction is highly significant positive correlated with organizational commitment, by reaching the score of (rx2v))=0,570 and probability p=0,001 (p<0,01). Teachers’ job motivation more dominantly influence organizational commitment compared to teachers’ job satisfaction
Volume: 5
Issue: 1
Page: 39-45
Publish at: 2016-03-01

An Experimental Study of the Unbalance Compensation by Voltage Source Inverter Based STATCOM

10.11591/ijpeds.v7.i1.pp45-55
Anas Benslimane , Jamal Bouchnaif , Mohamed Azizi , Khalid Grari
This work presents an experimental study of the unbalance compensation caused by the high speed railway substations in the high-voltage power grid with a shunt voltage source inverter based STATCOM. This experimental study is realized on a reduced scale prototype. The Control of inverter is implemented in a DSP card. The practical results presented in this paper are shown the performance of unbalance compensation by VSI_STATCOM in static and dynamic regime.
Volume: 7
Issue: 1
Page: 45-55
Publish at: 2016-03-01
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