Date of Award

29-3-2024

Document Type

Thesis

School

School of Electrical & Electroncis Engineering

Programme

Ph.D.-Doctoral of Philosophy

First Advisor

Dr.M.Nandhini Gayathri

Keywords

Electric Vehicles, Wireless Charging, Capacitive Power Transfer, Static Charging Mode, Dynamic Charging Mode

Abstract

Wireless Power Transfer (WPT) technologies, including Inductive Power Transfer (IPT) and Capacitive Power Transfer (CPT), offer promising solutions for Electric Vehicle (EV) charging applications. Compared to conventional IPT, a CPT method has no eddy current losses, lower electromagnetic interference (EMI), low system cost and weight, less misalignment problems, which gives the motivation to start this research work. The Proposed CPT method uses aluminum plates that generate electric fields by applying voltage on the plates to transfer the power from the transmitter (ground side) to the receiver (vehicle side).

This research introduces novel advancements in CPT systems to enhance power transfer efficiency and reliability for EV charging. A key focus is the Static Capacitive Power Transfer (SCPT) system, where a novel vertical six-plate arrangement is proposed to improve mutual capacitance, power transfer level, and efficiency. The vertical configuration of this arrangement reduces the size and weight of the coupler, offering advantages over conventional horizontal arrangements.

The transmitter side comprises four aluminium plates, while the remaining two plates, featuring mica, are strategically placed on the receiver side. Finite Element Analysis (FEA) using ANSYS Maxwell simulation is employed to determine plate dimensions and coupling capacitances, followed by LTspice simulations to validate the circuit model. Experimental verification at a transmitter distance of 300 mm demonstrates impressive results, with an output power of 6.06 kW and an efficiency of 92.3% achieved at a 60 mm air gap, contributing significantly to SCPT system advancement.

Additionally, this research proposes a novel vertical Dynamic Capacitive Power Transfer (DCPT) system for rail transit and on-road charging, aiming to enhance power transfer efficiency and CPT performance. The system utilizes a unique four-plate arrangement with optimized coupling capacitances and dielectric materials to improve output power. Experimental validation shows promising results, with an output power of 2.76 kW and a maximum efficiency of 92.6% achieved at a frequency of 1 MHz, highlighting the potential of DCPT for practical implementation in dynamic charging scenarios.

The presence of foreign objects, such as metallic ones, liquids, and other conductive materials, can be dangerous and reduce the effectiveness of the CPT system. For the widescale adoption of CPT, it is essential to develop an accurate and trustworthy Foreign Object Detection (FOD) system. Therefore, in addition this research proposes a FOD system based on deep learning techniques, designed to accurately identify foreign objects in CPT systems. The implementation of such a system holds the promise of enhancing the safety and reliability of CPT systems, contributing to its broader adoption in the realm of EVs. Overall, this research contributes to the advancement of CPT systems for EV charging, offering improvements in performance, efficiency, and safety, and holding promise for practical implementation in real-world applications.

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