A Filter Theory Approach to the Synthesis of Capacitive Power Transfer Systems

Resonant-coupled wireless power transfer (WPT) systems are typically modeled as circuits with inductively or capacitively coupled resonators. In a two-resonator system, the transmit and receive resonators are linked by a coupling coefficient, and the coupling can be adjusted for critical coupling, overcoupling, and undercoupling. In this work, we show that the coupled-resonator structure is equivalent to a filter structure and provide a demonstration of how filter theory can be used to design a capacitive WPT system. An advantage of this approach is that it provides access to a wide range of canonical structures and methods of impedance scaling to realize matched links. We show a maximally flat filter has a critically coupled response and an equiripple Chebychev filter has an overcoupled response. There is a relationship between frequency bandwidth in a filter design and spatial bandwidth in a WPT link. Therefore, the filter context can be used to synthesize wideband filters that are more robust to spatial variation than narrowband filters.

Automated summary

In this study, we demonstrate how a coupled-resonator structure, which is equivalent to a filter structure, can be used to design a capacitive wireless power transfer (WPT) system. This approach provides access to a wide range of standard structures and impedance scaling methods to achieve matched links.