Capacitive Resonant Single-Conductor System for Wireless Power Transfer to Devices with Metallic Embodiments

• Author / Creator

  Vital de Campos de Freitas, Susanna

• Although wireless power transfer (WPT) evolved drastically over the past decades, it still strives to be widely commercialized. The most two common methods of near-field contactless power transfer - inductive and capacitive power transfer - face significant obstacles regarding the misalignment and distance between receiver and transmitter devices. Moreover, these techniques are either not able to efficiently provide power while facing a conductive obstacle, or require multiple metallic plates to work.In order to power an electronic device with a metallic cover, a mixture of inductive, capacitive and single-conductor power transfers is proposed, being called as “Capacitive Resonant Single-Conductor”. The components of the system are described, designed, simulated and measured in the scope of this thesis. The proposed technology is designed to work according to the widely accepted AirFuel standard, at 6.78 MHz. Furthermore, variations to the final system are analyzed, while discussing its limitations.Finally, the structure’s impedances are affected by load variations, objects in its vicinity and relative position between transmitter and receiver devices. Therefore, adaptive matching circuits are of interest in WPT. The proposed circuit uses a transistor to control the amount of time that a capacitor is conducting, so that the resulting capacitance between this and other components creates a variable reactance related to the transistor’s base voltage. The final described adaptive matching is then applied to a regular 2-coil inductive link, to show its impact on this system’s self-resonance.

• Subjects / Keywords

  • Metallic Embodiment
  • Inductive Power Transfer
  • Capacitive Power Transfer
  • Wireless Power Transfer

• Graduation date

  Spring 2019

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/r3-e1g9-y667

• License

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