Electric vehicles (EVs) offer significant advantages over conventional internal combustion engine vehicles, including zero emissions and convenient overnight charging. However, there are still several challenges that need to be addressed. These challenges include limited driving ranges, slow refueling options while on-the-go, concerns related to the supply of lithium for batteries, and emissions associated with certain sources of electricity generation, such as coal. Adding on-board solar generation and/or fuel cell range extenders to EVs can help to mitigate some of these challenges, but also adds the need for optimal power electronic converters to manage the power flow of these multiple on-board energy sources, which is the focus of this thesis. This thesis first performs a comprehensive review of EV onboard chargers (OBCs) including charger system requirements by different standards and codes and different DC/DC power converters in the current infrastructures. Various power levels are compared and evaluated based on their component ratings, efficiency, cost, and power density. Secondly, there has been recent interest in harnessing solar power within electric vehicles, leading to the emergence of solar-charged electric vehicles (SEVs), which can offer extended driving ranges and less need for grid charging. These vehicles also offer a new opportunity for distributed generation when their traction batteries are fully charged, and the plugged-in vehicle is still generating solar energy. However, this also presents a unique power electronic dilemma. The OBC must exhibit high efficiency in two scenarios: firstly, during normal charging from the grid at power levels around 6.6 kW, and secondly, during vehicle-to-grid operation at significantly lower solar power levels, typically below 800 W. Unfortunately, conventional OBC designs tend to have low efficiency when operating at light loads. To tackle this challenge, this thesis proposes a novel bidirectional LLC-based converter, for use within the OBC, that achieves higher vehicle-to-grid efficiency at light loads than a traditional dual bridge converter. Detailed PLECS simulation results and experimental results are presented to verify the circuit. Thirdly, the presence of manufacturing variations can introduce parameter mismatches, resulting in voltage imbalances across capacitors in the proposed converter, or in other resonant converters with multiple transformer windings and two series-connected capacitors with a center connection. Such voltage imbalances pose significant concerns regarding safety and reliability. However, the existing capacitor balancing strategies developed for other converter topologies are not directly applicable to these new resonant multi-winding topologies. To address this issue, this thesis presents a novel method for achieving capacitor voltage balancing in a resonant multi-winding converter. The proposed method employs a straightforward approach to determine the appropriate balancing switching states. Time domain analysis is conducted to quantify the number of control cycles required, and an adaptive control strategy is introduced to enhance the balancing performance. The effectiveness of the proposed method and the beneficial effects on the converter's efficiency and bus capacitor sizes are validated through experimental investigations involving multiple bus capacitor sizes. Finally, though SEVs offer advantages over non-solar EVs, some challenges remain such as lithium supply concerns for large batteries, slow recharging, and driving range that is still limited compared to conventional vehicles. Fuel cell range-extended vehicles (FCREVs) can add a small fuel cell and hydrogen tank to allow quick refueling for long trips, and still use a reduced-size plug-in battery for the majority of short trips. This allows the driver to use efficient and convenient overnight charging for most daily commutes, and refuel with hydrogen on long-distance driving days if hydrogen stations are available. The smaller battery means that lithium requirements are reduced. Further, by adding on-board solar generation to a FCREV (S-FCREV), range can be further extended and grid charging requirements can be reduced. However, using conventional separate converters for a S-FCREV would be complex and costly, having a high number of semiconductor devices. To overcome this, the thesis proposes a practical multi-port converter that fulfills S-FCREV requirements with reduced components. A novel triple PWM and triple phase shift (TPTPS) control is proposed. Simulation and experimental results validate the proposed topology's operation and efficiency, offering a promising solution for integrating power electronics in S-FCREV applications. / Thesis / Doctor of Philosophy (PhD) / In the pursuit of sustainable transportation, recent scholarly investigations have placed significant emphasis on the advancement of electric vehicles (EVs) with a particular focus on solar-charged EVs and fuel cell range-extended vehicles (FCREVs) in order to help mitigate some of the drawbacks of battery EVs such as limited driving range, long refueling times, and charging impacts on the grid. Power electronic converters play a crucial role in managing the transfer of power between multiple energy sources, such as on-board solar panels, fuel cells, batteries, and connection to the grid. The objective of this thesis is to propose novel topologies and control for power electronic converters in solar-charged EVs and solar-charged FCREVs. Firstly, a novel bidirectional DC/DC topology is proposed for solar-charged EVs that allows a high-efficiency transfer of excess solar energy to the grid when the EV battery is full. Additionally, a novel control methodology for balancing the DC bus capacitors is introduced, aiming to reduce capacitor size and mitigate circulating unbalanced currents. Lastly, this thesis presents the pioneering practical implementation of a multi-port converter for a solar-charged FCREV, along with its adaptable control approach, enabling efficient power flow management among the grid, on-board battery, solar panels, and fuel cell.

In this work, a steady-state, one-dimensional model was developed for the cathode side of the PEM fuel cell. The model results compared well with available literature results. The effects of operating temperature, cathode gas pressure, cathode gas porosity, and membrane thickness were studied. Carbon materials used for the gas diffusion layer (GDL) were characterized. The materials were: untreated and Teflon-treated carbon paper and untreated and Teflon-treated carbon cloth. Physisorption data were analyzed using the BET and the BJH methods to determine surface area and pore size distribution. Capillary flow porometry measurements provided the bubble point, mean flow, and smallest pore diameters and pore size distribution. Gas permeability measurements were performed. Mercury/non-mercury intrusion porosimetry measurements were performed to obtain pore size distribution and cumulative pore volume. The microstructure structure of the materials was examined using Scanning Electron Microscopy. The elemental composition of the samples was measured using Energy Dispersive X-ray Spectroscopy.

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