Electrical & Electronics Engineering

Modernization of Indian railways has always been a question in focus for the development of the basic infrastructure of our country. Since the railways represent one of the best modes of transport available to the common people, it would be impossible to just keep increasing the fares to meet costs incurred due to maintenance, the large workforce and the expansion activities. The railways should consider upgrading itself to cutting-edge technologies for better efficiency and cost reduction. One such up gradation is the role of information technology and e-ticketing which is achieved with the help of RFID technology. This RFID technology has been extensively used in the identification process these days with the help of a card and a reader. The idea has evolved from a systematic study of the computerization of railways and the loopholes in the present day system. A simple theoretical model is proposed which when implemented could result in an easier and better management of the tedious ticketing process.

irtual laboratories that animate scientific phenomena are becoming an increasingly popular method to teach students. Electrical engineering is considered difficult to understand as it demands a high level of imagination. This difficulty can be dealt with to a large extent by developing visual aids in the form of animations. Animations can help students to grasp the idea quickly and therefore can serve as an effective aid for the learning process. This paper deals with the development of such a teaching aid to tackle a particular problem in Electrical Drives and Power Electronics (ED&PE). The problem is that of the electrical drive train of a hybrid electric vehicle (HEV) that can regenerate power during braking or whenever required (Plug-in HEV, PHEV). This paper attempts to give a step-by-step insight into the various design choices, the operation of the converters and their controls, the learning objectives and finally the development of the graphic multimedia for this drive train.

This paper presents a generalised analysis of
a multi-frequency system with two transmitter coils, each
carrying a current of a different frequency and deals with
the frequency decoupling of multi-coil IPT systems. Frequency
decoupling as an alternative to spatial decoupling is suggested
and a design procedure considering the mutual coupling
between all the coils in the IPT system, is elucidated. Simulation
results of a 100 kHz and 30 kHz system are presented and
experimental results that validate this theory are provided.

This paper presents a comparative analysis of Multi-Coil Inductive Power Transfer (MCIPT) systems. A multi-coil magnetic system can be decomposed into a single system of coils using matrix manipulation when the system is linear. A comparitive analytical study of air-cored coils to estimate the magnetic parameters-L, M, k of several coil shapes-circular, rectangular, square, segmented circular and segmented rectangular (DD) is then carried out. A misalignment shape characteristic is obtained and comparisons brought out. Important criteria to be considered for misalignment tolerant MCIPT is also described. A boundary for performance limits of misaligned multi-coil IPT systems is presented.

This paper deals with a generic methodology to evaluate the magnetic parameters 1 of contactless power transfer systems. Neumann's integral has been used to create a matrix 2 method that can model the magnetics of single coils (circle, square, rectangle). The principle 3 of superposition has been utilised to extend the theory to multi-coil geometries such as double 4 circular, double rectangle and double rectangle quadrature. Numerical and experimental validation 5 has been performed to validate the analytical models developed. A rigorous application of the 6 analysis has been carried out to study misalignment and hence the efficacy of various geometries to 7 misalignment tolerance. Comparison of single-coil and multi-coil IPT systems (MCIPT) considering 8 coupling variation with misalignment, power transferred and maximum efficiency is carried out.

This thesis deals with the modelling and application of magnetic fields in roads. The backbone technology being inductive power transfer (IPT) for electric vehicles. The magnetics for energy transfer in vehicles, can be adapted for heating steel fibres in roads, referred to as self-healing and modelling this is a second aspect of this thesis. The first sections of this thesis is dedicated to an overview of modelling techniques for coil design of IPT systems using both analytical and semi-analytical tools. A detailed literature review of techniques is followed by a comparison highlighting the strengths and weakness of techniques in terms of ease of use, computational efficiency, application to material interfaces etc. Analytical modelling of single and multi-coil configurations of IPT systems is carried out subsequently. The theory of partial inductance is used to model these geometries, to assess the impact of system parameters such as coupling, power transferred and magnetic efficiency with shapes of couplers and misalignment. Next, the problem of misalignment is highlighted by considering a distributed IPT system. The analytical modelling and experimental analysis of misalignment - lateral and longitudinal is performed. Edge effect is observed and experimentally validated. The second part of this thesis is dedicated to a multi-objective optimization based on the results of the developed analytical model. The goal being the development of a prototype IPT system for powering light EVs. The double rectangular (DR) coupler is chosen as the geometry for power transfer. Several geometry parameters - turns, ferrites (number, dimensions), gap between ferrites etc. are considered as design variables. Efficiency, area related power density and weight are considered as the optimization targets. Pareto fronts are developed and a particle is chosen for the development of a prototype. An experimental set-up is built consisting of a 85 kHz inverter, compensated charge-pads, rectifier and resistive load. The inverter is based on SiC MOSFETS and SiC Schottky anti-parallel diodes, the rectifier made from the same diodes. Phase shift control of the inverter legs is used to control power flow. An experimental analysis to validate the magnetic models is also developed. The third part of this thesis deals with system level economic analysis of IPT technology. A case study of bus fleet is considered and a generic methodology is developed to determine driving range as a function of mass and frontal area of the EV. The economic analysis is performed also identifying the trade-offs between road coverage of IPT, efficiency and battery size. Finally, the thesis culminates with a vision toward a future highway. Such a highway is expected to undergo a functional upgrade to handle electrification of transportation. This evolves around the integration of IPT systems, with low maintenance inductive healing asphalt roadways and renewable energy generation. The modelling challenges to such an integration is studied both using simulations and experiments. A case study for sizing renewable energy in a highway (A12) in the Netherlands using IPT is detailed.

The grid integrated renewable energy sources are becoming a common area of interest for power generation in the recent times. The design and development of efficient interfacing technologies to interconnect renewable energy sources with grid is catching a lot of attention among the researchers these days. The interfacing unit becomes crucial as renewable energy sources when directly connected to grid, can inject harmonic components that may deteriorate the quality of power. This paper proposes a mechanism to use shunt active filter as an interface between renewable energy sources and grid with a modified and efficient control scheme. The shunt active filter with this modified controller controls the real power supplied by the grid (source) in addition to its usual functions such as reactive power compensation, power factor correction and harmonic elimination. The non-linear load is diode bridge rectifier feeding resistive load and the unbalanced load also introduced to verify the controller performance. The simulation of the proposed system under both balanced and unbalanced load conditions have been done and the obtained results prove the effectiveness of using a shunt active filter as the interfacing unit for grid integrated renewable energy system.

The long established battery chargers are having many drawbacks such as prominent ripple charging current, less efficiency and bulky in size. To overcome these drawbacks of conventional battery charger, several charging circuits have been proposed and inevitability force to design a high-performance battery charger with small in size and improved efficiency. In this paper solar photovoltaic system based half-bridge series–parallel resonant converter (HBSPRC) charger is proposed for battery interface. The converter is designed to abolish low and high-frequency ripple currents and thus take full advantage of the life of secondary battery circuit. This is achieved by designing converter switches turn on at zero current and zero voltage with switching frequency greater than that of resonance frequency which leads to freewheeling diodes need not have very fast reverse-recovery characteristics. The performance of the power converters depends upon the control method adopted; in this work f...

Power systems are steadily growing to meet the power demand. Increase in demand is a challenging concern in developing countries. To meet this ever-increasing demand, enhancement of power generation is required in conventional as well as non-conventional form. Conventional power generation has its own limitations such as land requirement and environmental concern for future enhancement. Conventional power generation has its own limitations such as land requirement, environmental associated pollution and exploitation of fossil fuel. At the same time, worldwide, distributed generations (DGs) are contributing more due to sustainability, pollution free environmnet, ease of energy, and load management. It is expected that the renewable energy capacity will reach 30 GW over the next two decades, merely 10% new capacity addition of DG during this period [1]. Integration of DG into grid is in practice for the past few decades in many countries. Conventional power system consists of thermal, hydro, and nuclear power plants interconnected with grid, transmission system, and distribution system. The purpose of controlling generation is to track load change by adjusting the generation automatically to restore the frequency and tie-line power flow within the prescribed limit using automatic generation control (AGC) in a conventional power system. Under normal conditions, generators are operated at a scheduled output, and system frequency is maintained constant [2]. The primary objective of AGC is to minimize

This paper proposed a method to reduce the switching losses in a direct-current-direct-current boost converter. The proposed method uses a capacitor switched regenerative snubber circuit to reduce the turn-off losses of the IGBT in the boost converter, and thus it improves the overall efficiency of the converter. The circuit uses no additional magnetic components and enjoys a simple control strategy. Two 500W prototypes, that is one with and the other without the regenerative snubber have been tested to evaluate and demonstrate the impact of the proposed regenerative snubber circuit.