Aerodynamic Fluid Bearings for Capacitive Power Transfer and Rotating Machinery

Wireless power transfer (WPT) and electromechanical power conversion are traditionally accomplished with magnetic (inductive) techniques for a wide range of applications. Electrostatic (capacitive) approaches to WPT for electric machinery have had limited success over the history of power conversion due to the low power density, low mechanical robustness and cost that could not compete with magnetic steel. Recently, high frequency (kHz-MHz) power electronics have reintroduced capacitive techniques as a viable option for WPT over short distances (< 2mm) and in niche rotating machinery designs. To further the practicality of capacitive techniques, capacitive coupling must be maximized. This paper proposes the use of aerodynamic fluid bearings to maximize capacitive coupling between stationary and rotating surfaces by minimizing their separation distance. This technique also allows for the estimation of mechanical system parameters such as speed. Operational characteristics and design techniques are presented and corroborated with experimental results.