Enhancing misalignment tolerance in inductive power transfer systems: design and real-world applications for electric mobility

Amr Azab Mostafa

doi:10.17918/00001923

Inductive Power Transfer (IPT) systems have been increasingly recognized for their potential in electric mobility applications, primarily for their capability to transmit power wirelessly. However, the efficiency and robustness of these systems are often compromised due to misalignments between the transmitter and receiver coils. This dissertation presents a rigorous investigation into the challenges presented by misalignment in IPT systems and introduces novel designs and control strategies to address these challenges, with implementations in real-world applications for electric vehicles (EVs) and autonomous underwater vehicles (AUVs). First, a detailed analysis of the implications of coupler misalignment on system performance is introduced. A hybrid tuning strategy, combining voltage and frequency tuning mechanisms, is systematically proposed. This approach facilitates output power regulation, adapting to varying misalignment scenarios and EV battery voltages, eliminating the necessity for supplementary converters. This approach effectively mitigates power fluctuations caused by misalignment. However, it emphasizes the need to address the foundational issue of misalignment tolerance directly at its source: the design of the coupler structure. Next, the dissertation shifts to magnetic coupler design. The rationale for integrating compensation inductors within the coupler structure is followed by the introduction of a proposed cross-coupled LCC-P system. This design seeks to enhance misalignment tolerance while reducing overall system volume. The chapter substantiates the design's merits through a prototype that demonstrates power transfer capabilities, and misalignment tolerance. Cylindrical coupler structures are analyzed, with a specific emphasis on their potential integration within Autonomous Underwater Vehicles (AUVs). Three core challenges are methodically addressed: Electromagnetic Interference (EMI), losses attributed to the transfer medium, and most critically, misalignment. The 360° folded spatial unipolar coupler, when analyzed, showcases its capability to confine the electromagnetic field in a manner that mitigates EMI. However, this confinement, while beneficial in reducing interference, introduces complexities related to rotational misalignment that necessitate further investigation. Finally, the split solenoid structure and its derivative compact receiver design are proposed. These designs inherently exhibit resistance to rotational misalignment, making them ideal candidates for challenging marine environments. The primary research focus transitions to axial misalignment and efficiency optimization. A comprehensive study of these coupler structures is presented, delineating the trade-offs in terms of physical dimensions, tolerance to misalignment, and efficiency under optimal alignment conditions. The research culminates with the development and validation of experimental prototypes capable of transmitting up to 15.4 kW of power in both air and saltwater environments. These establish them as the highest-powered hull-compatible systems documented in literature for autonomous underwater vehicles. In conclusion, this dissertation provides a systematic exploration into the challenges of misalignment within IPT systems, presenting a range of solutions substantiated through rigorous analysis, simulations, and empirical testing. As the domain of WPT continues to evolve and expand, so does the potential for innovative advancements. Anticipated future work will build upon the foundation established in this research, seeking to integrate the derived insights into emerging applications, notably including unmanned aerial systems (UAS).

Enhancing misalignment tolerance in inductive power transfer systems: design and real-world applications for electric mobility

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Enhancing misalignment tolerance in inductive power transfer systems: design and real-world applications for electric mobility

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