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oai:figshare.com:article/32641500 2026-10-01T16:22:51Z portal_1172 item_type_8 month_year_10_2026

Wireless power transfer system for electric vehicle charging Iman Okasili (24170022) PUREID: 648248608 Wireless Power Electronics WPT Converters DC-DC Converter CUK Class E Resonant Resonant Converter Resonance Inductive Charging Electric Electric Vehicle Charging EV In order to satisfy the demand for the ergonomic charging of batteries in response to the unprecedented increase in battery-powered device use, wireless power transfer has seen a major resurgence in interest and development. Wireless power transfer offers a fast and easy connection method for supplying power to charge portable devices. The most prominent medium for conveying power in this manner is through the use of inductive coupling. Inductive coupling is primarily used due to its comparatively safe operation and high energy density. The most common application of wireless power transfer is for small portable devices for which systems operate with relatively high and stable inductive coupling. However, in recent years, particularly with the increased uptake of electric vehicles, wireless power transfer systems have been applied to larger loads with lower and more volatile inductive coupling. Implementing inductive WPT for EV charging faces several challenges which stem from the variable nature of the power transfer medium, these issues are as follows: •Low power transfer rates as systems rely on fine tuning of passive components to specific coupling factors. This lowers the power transfer rates by causing poor conductive efficiency or deformation in waveforms. •High passive component stress caused by large voltage/current spikes when passive components are not tuned to the operating coupling factor. A change in coupling factor can cause shifts in the system reactance meaning severe imbalance between inductive and capacitive parts. The switched waveforms can then show drastic spikes which ultimately result in heavily reduced passive component lifespan. •Low switching efficiency is caused by operation at nonoptimal coupling factors causing power dissipation on each switching cycle. This increases the needed size of auxiliary components such as heat sinks and affects component life span. •Large space consuming and complicated systems with many converter stages needed to control waveforms for effective power transfer. This PhD project sets out to investigate and acquire a new solution based on resonant converters to create a new sleek system providing crucial space savings for portability and robustness that can also deal with the volatile nature of the power transfer medium. The basis of which this new resonant converter is built upon is that of introducing WPT operation to an isolated Buck-Boost converter. Such that the Buck-Boost converter characteristic can be maintained to allow for control of the output power and voltage for effective battery charging. However, upon investigation the ability of a Buck-Boost converter to operate with duty cycle control was heavily impacted by the introduction of the loosely coupled coils in substitute of a high frequency transformer as seen in contemporary isolated Buck-Boost topologies. This prompted the addition of incorporating Class E2 converter design methodology to overcome poor functionality to hopefully regain duty cycle control. The merging of these design principles and unique contributions has culminated in a new and novel system that is able to transfer significant levels of power across loosely coupled inductors with exceptional efficiency. However, duty cycle control was still shown to be significantly impacted due to the restriction of Class E2 converter design relying on a fixed switching duty cycle. A design methodology has been constructed to detail the process and to ensure repeatability and reliable design of the system. When comparing the original investigation of modified isolated converters seen in Chapter 4. Investigation of Isolated Buck-Boost and Class E2 Converters for Wireless Power Transfer to the most recent design method in Chapter 5. New Design of Buck-Boost Resonant Converter for Wireless Power Transfer New Design of Buck-Boost Resonant Converter for Wireless Power Transfer. The modified isolated converter showed a lowly sub 10% operation efficiency with drastic voltage and currents spikes across crucial components. Whereas the final design method showcases efficiencies at over 90% in some scenarios with consistent ZVS/ZDS and smooth, spike-free waveforms which improves component lifespan. However, the design currently relies on limited by inspection tuning to yield desirable operation. This thesis comprehensively showcases the parameters needed for tuning and the process in which proper tuning is achieved. This means the design process is not yet fully optimised and can be improved upon. The thesis closes with a summary of the work conducted and a review of the success of the design methodology and newly created converter. Thesis is embargoed until 31 December 2027. 2026-10-01T16:22:51Z Text Thesis 10.17034/32641500.v1 https://figshare.com/articles/thesis/Wireless_power_transfer_system_for_electric_vehicle_charging/32641500 All Rights Reserved Open Access after 2027-12-31