A Novel T-Connected Autotransformer-Based 18-Pulse AC–DC Converter for Harmonic Mitigation in Adjustable-Speed Induction-Motor Drives

This paper presents the design, analysis, and development of a novel autotransformer-based 18-pulse AC-DC converter with reduced kilovoltampere rating, feeding vector-controlled induction-motor drives (VCIMDs) for power-quality improvement at the point of common coupling (PCC). The proposed autotransformer consists of only two single-phase transformers for its realization against three single-phase transformers required in other configurations. The proposed 18-pulse AC-DC converter is suitable for retrofit applications, where, presently, a six-pulse diode bridge rectifier is being used. A set of power-quality parameters, such as total harmonic distortion (THD) and crest factor of AC mains current, power factor, displacement factor, and distortion factor at AC mains, THD of supply voltage at PCC, and DC-bus-voltage ripple factor for a VCIMD fed from an 18-pulse AC-DC converter, are computed to observe its performance. The presented design technique provides flexibility to give an average DC output from the proposed converter, which is the same as that of a conventional three-phase diode bridge rectifier. However, it is also possible to step-up or step-down the output voltage as required. The effect of load variation on VCIMD is also studied to observe the effectiveness of the proposed harmonic mitigator. A laboratory prototype of the proposed autotransformer-based 18-pulse AC-DC converter is developed to validate the design and simulation model.     

Polygon-Connected Autotransformer-Based 24-Pulse AC–DC Converter for Vector-Controlled Induction-Motor Drives

This paper presents a novel autotransformer-based 24-pulse AC-DC converter feeding vector-controlled induction motor drives (VCIMDs) for improving power quality at the point of common coupling. The DC-ripple-reinjection technique is used in achieving the pulse multiplication in a 12-pulse AC-DC converter. The design of the proposed autotransformer is given, and necessary modifications are made in it to provide the same output DC voltage as a 6-pulse diode-bridge AC-DC converter to make it suitable for retrofit applications. The proposed 24-pulse AC-DC converter is found capable of suppressing up to the 21st harmonics in the supply current along with the power-factor improvement close to unity in the wide operating range of the drive. A set of power-quality indexes at input AC mains and on DC bus for a VCIMD fed from various AC-DC converters are also given to compare their performance. A prototype of the proposed autotransformer-based 24-pulse AC-DC converter is developed, and test results are presented to validate the developed design procedure and the simulation models of this AC-DC converter under varying loads.     

Identification and Determination of Bio-Diesel in Diesel

Bio-diesels play an important role in meeting future fuel requirements in view of their nature (less toxic), and have an edge over conventional diesel as they are obtained from renewable sources. Bio-diesel blends up to 20% in diesel are being used at present. In this article, the determination of bio-diesel in diesel both by conventional and spectroscopic methods is described. These methods are simple, fast and reliable and can be used to determine bio-diesel in a wide range of concentrations of up to 25% blends.     

Analysis of charge density and Fermi level of AlInSb/InSb single-gate high electron mobility transistor

A compact model is proposed to derive the charge density of the AlInSb/InSb HEMT devices by considering the variation of Fermi level, the first subband, the second subband and sheet carrier charge density with applied gate voltage. The proposed model considers the Fermi level dependence of charge density and vice versa. The analytical results generated by the proposed model are compared and they agree well with the experimental results. The developed model can be used to implement a physics based compact model for an InSb HEMT device in SPICE applications.     

Validation and quantification of neonicotinoid insecticide residues in rice whole grain and rice straw using LC-MS/MS

An efficient analytical method was developed and validated using a modified QuEChERS method and LC-MS/MS for the detection and quantification of neonicotinoid insecticide residues in rice whole grain and rice straw. The samples were extracted using acetonitrile and cleaned up by dispersive solid-phase extraction. Validation based on five fortification levels showed good recoveries of neonicotinoids ranging from 75% to 116 % and 60% to 105 % for rice whole grain and straw, respectively. The precision ranged between 3% and 17 %, and 2% and 10 % for grain and straw, respectively. The limit of detection was from 0.007 to 0.0084 mg kg^?1 and 0.005 to 0.15 mg kg^?1 and the limit of quantification was in the range of 0.024–0.028 mg kg^?1 and 0.016–0.051 mg kg^?1 for rice whole grain and rice straw, respectively. Monitoring of farm gate samples indicated that, out of 24 samples, 1 rice whole grain sample was contaminated with thiamethoxam residues (0.07 mg kg^?1).     

Performance Analysis of Reversed Binary Decision Diagram Pass Transistor Logic Synthesis

Binary decision diagrams (BDDs) are the most frequently used data structure for the representation and handling of Boolean functions because of their excellent time and space efficiencies. In this article, a reversed BDD‐based pass transistor logic (PTL) logic synthesis is presented for low‐power and high‐performance circuits without exploiting the canonical property of BDDs. The procedure of the reversed BDD transformation into PTL is achieved by a one‐to‐one correspondence with the BDD node and PTL cell. Layouts are generated for the benchmark circuits and simulated in terms of power dissipation, propagation delay and area. The reversed BDD technique performs better in terms of area, delay and power dissipation due to the regularity, a reduced critical path, less interconnection wires, a multiplexer‐based construction of PTL circuits, and less switching activities. Copyright © 2011 John Wiley & Sons, Ltd.     

Intelligent power management in micro grids with EV penetration

Large deployment of Electric Vehicles (EVs) adds new challenges in the operation of a microgrid. Assuming that a number of EV owners allow their batteries to charge when their cars are parked, this paper proposes an approach that aims to find suitable individual active power set-points corresponding to the hourly charging rate of each EV battery connected to the microgrid. A multi agent system based controller is designed to find these active power set points for optimal power management of EVs, distributed energy resources in the microgrid, and the loads.     

Effect of aspect ratio on convection in a porous enclosure with partially active thermal walls

The aim of the present numerical investigation is to understand the effect of aspect ratio and partially thermally active zones on convective flow and heat transfer in a rectangular porous enclosure. Five different heating and cooling zones are considered along the vertical walls while the remaining portions of the sidewalls and top and bottom of the enclosure are adiabatic. The Brinkman-Forchheimer extended Darcy model is used in the study. The governing equations are solved by the finite volume method with the SIMPLE algorithm. The computations are carried out for a wide range of parameters and the results are presented graphically. The results reveal that the location of heating and cooling zones has a significant influence on the flow pattern and the corresponding heat transfer in the enclosure. The rate of heat transfer approaches to a constant value for very low values of the Darcy number. The heat transfer rate is decreased on increasing the aspect ratio.     

Multi-objective parameter estimation of induction motor using particle swarm optimization

In order to simplify the offline parameter estimation of induction motor, a method based on optimization using a particle swarm optimization (PSO) technique is presented. Three different induction motor models such as approximate, exact and deep bar circuit models are considered. The parameter estimation methodology describes a method for estimating the steady-state equivalent circuit parameters from the motor performance characteristics, which is normally available from the manufacturer data or from tests. The optimization problem is formulated as multi-objective function to minimize the error between the estimated and the manufacturer data. The sensitivity analysis is also performed to identify parameters, which have the most impact on motor performance. The feasibility of the proposed method is demonstrated for two different motors and it is compared with the genetic algorithm and the classical parameter estimation method. Simulation results show that the proposed PSO method was indeed capable of estimating the parameters over a wide operating range of the motor.     

A new class of Sol–gel derived LiM1xM2yMn2?x?yO3.8F0.2 (M1?=?Cr, M2?=?V; x?=?y?=?0.2) cathodes for lithium batteries

A series of LiM_1xM_2yMn_2−x−yO_3.8F_0.2 (M₁ = Cr, M₂ = V; x = y = 0.2) cathodes, viz., LiMn₂O_3.8F_0.2, LiCr_0.2Mn_1.8O_3.8F_0.2 and LiCr_0.2V_0.2Mn_1.6O_3.8F_0.2 along with native LiMn₂O₄ have been synthesized by Citric Acid assisted Modified (CAM) sol–gel method, with a view to understand the effect of synthesis methodology and the effect of dual category dopants, viz., anion and/or cation upon spinel cathodes individually. An acceptable capacity retention (94%) observed up to 50 cycles for native LiMn₂O₄ cathodes is attributed to the significance of CAM sol–gel method. Similarly, the encouraging charge–discharge results of LiMn₂O_3.8F_0.2 (130 mAh g⁻¹) and LiCr_0.2Mn_1.8O_3.8F_0.2 (142 mAh g⁻¹) cathodes revealed a possible augmentation in the reversible capacity behavior of the spinels upon F⁻ substitution at 32e site and the simultaneous substitution of Cr³⁺ and F⁻ at 16d and 32e sites respectively.