Inductive Power Transfer Through Saltwater

TL;DR

This study explores inductive power transfer through saltwater using resonant loop-gap resonators, demonstrating efficiency dependence on conductivity and frequency, and proposing methods to enhance transfer efficiency.

Contribution

It introduces a novel approach to IPT through conductive saltwater with a detailed circuit model and strategies for efficiency improvement.

Findings

Efficiency decreases with higher conductivity

Resonant frequency affects power transfer performance

Partitioning saltwater improves efficiency

Abstract

We investigated inductive power transfer (IPT) through a rectangular slab of saltwater. Our inductively-coupled transmitters and receivers were made from loop-gap resonators (LGRs) having resonant frequencies near 100 MHz. Electric fields are confined within the narrow gaps of the LGRs making it possible to strongly suppress the power dissipation associated with electric fields in a conductive medium. Therefore, the power transfer efficiency in our system was limited by magnetic field dissipation in the conducting medium. We measured the power transfer efficiency as a function of both the conductivity of the water and the resonant frequency of the LGRs. We also present an equivalent circuit model that can be used to model IPT through a conductive medium. Finally, we show that using dividers to partition the saltwater volume provides another means of enhancing power transfer efficiency.