Arrangement Free Wireless Power Transfer for Mid-range Applications via Electrically Strong Resonance

Abstract

Wireless Power Transfer (WPT) is a cutting-edge technology that enables energy transfer without the need for physical connectors, offering significant potential for various applications. This thesis provides an in-depth examination of the challenges, benefits, and trade-offs associated with different WPT technologies, with a particular focus on enhancing the degree of freedom between power transmitters and receivers. Achieving greater freedom in positioning and mounting of these components is critical for mitigating issues related to wear, damage, and maintenance costs, thereby improving the overall reliability and usability of WPT systems. The realm of WPT can be divided into near-field and far-field methodologies, each characterized by distinct degrees of freedom and efficiency considerations. Near-field WPT includes technologies such as Inductive Power Transfer (IPT) and Magnetic Resonant Wireless Power Transfer (MRWPT). IPT is limited by its requirement for close proximity between the transmitter and receiver, typically in the millimeter to centimeter range, resulting in minimal spatial freedom. MRWPT, developed by MIT researchers in 2007, offers greater flexibility but its efficiency is highly dependent on the relative orientations of the transmitter and receiver. Despite advancements in these technologies, the quest for an optimal balance between system complexity and freedom remains ongoing. Far-field WPT, particularly microwave WPT, provides another approach, achieving high efficiency through focused energy transmission. However, this method restricts freedom to a quasi-one- dimensional domain, and while three-dimensional freedom can be attained through omni-directional energy dispersion, it comes at the cost of significant efficiency loss. This thesis underscores the necessity of balancing efficiency with the degree of freedom to drive broader adoption of WPT technologies. Central to this research is the introduction of a novel two-dimensional WPT paradigm utilizing Spoof Surface Plasmon Polaritons (SSPP) and surface waves. This approach offers a middle ground, providing greater flexibility than one-dimensional systems while maintaining reasonable efficiency. The use of plasmonic metamaterial structures, such as lattice-type SSPP unit-cells, allows for fine-tuning of propagation characteristics, optimizing the system for microwave applications. Additionally, the implementation of surface wave receivers and the incorporation of non-reciprocal ferrite components enhance the specificity and effectiveness of power transfer. Beyond two-dimensional WPT, this thesis proposes Electrical Resonant Wireless Power Transfer (ERWPT) as a significant advancement over traditional MRWPT. ERWPT leverages the monopole capabilities of electric fields to overcome the spatial limitations imposed by magnetic dipole configurations. This new approach facilitates consistent PTE despite variations in receiver arrangement, demonstrating non-radiative power transfer of up to 50 watts with a PTE of 46% over a distance of 2 meters. The theoretical foundation of ERWPT is rooted in Maxwell's equations and the fundamental equivalence of electric and magnetic forces, providing a robust framework for exploring electric field- based WPT. The findings of this research highlight the potential of ERWPT to address longstanding challenges in WPT, offering a more versatile and efficient solution compared to magnetic field-based approaches. By revisiting the principles of electromagnetism and examining the intrinsic properties of electric and magnetic fields, this thesis lays the groundwork for future advancements in WPT technologies. The practical implementation of ERWPT at midrange distances represents a significant step forward, with implications for a wide range of applications, from consumer electronics to industrial automation. In conclusion, this thesis contributes to the WPT field by presenting innovative solutions that enhance the flexibility and efficiency of power transmission systems. The introduction of the development of ERWPT demonstrate the potential for overcoming current limitations and driving the next generation of wireless power technologies. This research not only advances our understanding of WPT mechanisms but also paves the way for practical and versatile wireless power solutions capable of meeting the diverse needs of modern technology.