Experimental Characterization and Prediction of Radial and Thickness Mode Power Transfer Capability in Through-Metal Acoustic Power Transfer
Through metal acoustic power transfer is an emerging wireless solution for battery charging in hazardous and sensitive environments where electronics are enclosed within sealed metal structures without electrical feed through. Power transfer is achieved utilizing reverse and direct piezoelectric effects via acoustic wave propagation through the metal barrier. The achievable power, often targeting hundreds of watts, is strongly influenced by different factors, such as, material properties, geometry, dimensions of the metal and piezo, and their bonding, making maximization of power transfer capability critical. This work experimentally investigates the terminal electrical characteristics of multiple prototypes, representing realistic scenarios. It compares power transfer capability in thickness and radial resonance modes for piezo metal assemblies, enabling appropriate mode selection and power electronics interface design. A figure of merit (FOM) is proposed for rapid screening and ranking of configurations as far as the power transfer capability is concerned.