Venugopal Prasanth

Distributed IPT Systems for Dynamic Powering: Misalignment Analysis

This paper looks into the problem of misalignment in distributed inductive power transfer systems. The idea of varying mutual inductance longitudinally referred to as longitudinal misalignment is introduced here. The analytical expressions for both lateral and longitudinal misalignment are derived. Experimental validation of the theory developed is also performed. In case of conventional rectangular coils, the vertical sections are not symmetrical. This was observed in the mutual inductance profile experimentally, and the concept of “Edge Effect” was introduced to explain the same. An inductor with symmetrical ends was constructed to tackle this problem.

A contactless power transfer — Supercapacitor based system for EV application

Design of a contactless power transfer system with supercapacitor based primary energy storage for electric vehicle application is described in this paper. The contactless power transfer system which uses inductively coupled coils to transfer power over a large air gap has been developed. Compensation topologies and the operational frequency of power transfer system have been studied in order to obtain maximum efficiency and high power transfer capability. An experimental setup is built using the design considerations so derived and design parameters for such a system is laid out. Finally, a microcontroller charge control mechanism is implemented to operate the system in a safe region and avoid over charging of supercapacitors.

Study of misalignment for On Road Charging

A major problem concerning On Road Charging of Electric Vehicles via Inductive Power Transfer (IPT) links is the large variation in power transfer and efficiency due to displacement of the secondary from the primary. This paper looks into this problem referred to as misalignment, both laterally and longitudinally. For lateral misalignment, experimental results were obtained by considering horizontal and vertical coils separately. The technique of combining the quadrature coils to form the quadrature pickup so as to obtain a flatter mutual inductance profile is suggested by directly combining the individual secondary coils. Longitudinal misalignment is particularly of interest when sectional primaries are to be constructed. In case of longitudinal misalignment, unsymmetrical mutual inductance profile at the extremes of the primary was observed experimentally. The concept of “Edge Effect” was introduced to explain the same. A solution to this problem is suggested and the concept of Best Efficiency Point (BEP) introduced. Theoretical efficiencies were obtained to select the best configuration of the primary for power transfer.

Generic methodology for driving range estimation of electric vehicle with on-road charging

An analytical estimation of driving range of electric vehicles (EVs) with contactless on-road charging system is presented in this paper. Inductive power transfer (IPT) systems with different configurations (static, dynamic), power levels and road coverage have different (and non-linear) impact on the driving range. A generic methodology has been developed to estimate the driving range of any EV by defining a set of formulae linearly dependant on vehicle mass, frontal area, IPT system configuration, power level and road coverage area. Driving cycle constants are defined to take into account the variation in the consumption pattern of the EV with the velocity profile.

Economic and CO2 Emission Benefits of a Solar Powered Electric Vehicle Charging Station for Workplaces in the Netherlands

The paper analyses the economic and environmental benefits of charging electric vehicles (EV) at workplaces in the Netherlands using photovoltaic panels (PV). A 10kW EV-PV charging system is used to charge the electric cars directly from photovoltaic panels. The cost of using a gasoline vehicle is compared with that of an electric vehicle that is charged from the grid or from solar panels. It is found that charging EV from PV results in huge savings in fuel cost, taxes and lower CO2 emissions. A comparison is made for solar panels installed on rooftops and as a solar carport and the impact of feed-in tariffs on PV generation revenues is evaluated.

Multi-objective optimisation of a 1-kW wireless IPT systems for charging of electric vehicles

Inductive power transfer (IPT) systems for on-road dynamic charging of electric vehicles (EVs) must employ tracks with minimal copper and ferrite core material for improving coupling and field shaping without sacrificing on power transfer efficiency across the air gap. This paper details the multi-objective optimisation of IPT coil systems with respect to efficiency of power transfer (η), material weight or cost (w), and area-power density (α) as required in EV applications. A combination of detailed analytical calculations and experimentally verified 3D finite element models is used to analyse performance of IPT systems with polarized coupler topology [referred to as double D(DD) coils], I-shaped ferrite cores for field shaping and aluminium plates to reduce stray or leakage magnetic fields. An multi-objective pareto optimisation using Particle Swarm algorithm of a scaled 1kW prototype system with a 15 cm airgap is presented.

Loss model and control stability of bidirectional LCL-IPT system

This paper aims to present a loss model and investigate the stability of a LCL-IPT system for EVs. For the experimental set-up and loss model, Silicon Carbide MOSFETs have been used as the converter switches. The zero-voltage-switch contour area of the converter over the entire operation range is presented and the optimum dc-link voltages for efficiency maximization are also shown. The stability of the system consisting of a single pickup, is investigated to highlight potential issues. Voltage-cancellation technique is utilized to control both the primary and secondary side currents.

Drivetrain of electric car: Development of virtual laboratory for E-learning

Virtual 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.

A sectional matrix method for IPT coil shape optimization

In this paper, Neumanns integral is evaluated for computing self-inductance using a multi-turn sectional matrix method. Analytical equations are derived considering the increase in dimensions of the coil due to an impinging air-gap between the turns. The resulting sectional self-inductance matrix is computed and the concepts of sectional partial self-inductance and sectional partial mutual inductance are introduced. The effects of the various partial inductances are considered as a function of the air-gap, dimensions and turns. Further, the mutual inductance of a pair of coils is considered and the coupling is obtained analytically. The coils considered are to be used for shape optimization of IPT coils. Finally, the results are compared with experimentation. This technique being generic can be applied to a number of different polygonal shapes and can be further simplified by the theory of vector decomposition of current elements. A case study with self-inductance and perimeter as optimization objective is considered.

Comparative analysis of on-load tap changing (OLTC) transformer topologies

On-load tap changing (OLTC) transformers are widely used for voltage control in the distribution network. The paper provides a comparative analysis of different OLTC topologies for the design of a power electronic (assisted) tap changer. Eleven different topologies are compared on the basis of voltage and current rating of the transformer windings and tap switches, using a p.u. methodology. The topologies are designed in such a way that they can provide both positive and negative compensation of the grid voltage. The p.u. comparison is a beneficial tool for OLTC designers to suitably choose the right topology based on the voltage and power levels of the network, type of solid-state switch used and the voltage regulation application.