Self-Detachable Through-Metal Acoustic Wireless Power Transfer

Abstract

Unlike electromagnetic waves, acoustic vibrations waves can be used to transfer power directly through metal structures without being shielded. In this paper, a novel design of a self-detachable acoustic wireless power transfer system that can be used to transfer power through the thickness of a steel plate is presented, which does not require the use of any couplant. Electro-permanent-magnets (EPM's) were used to provide magnetic clamping force along the perimeter of the receiver transducer disc to enhance the coupling to the steel plate, while the transmitter transducer was bonded to the other side of the plate. The EPM clamping force can be switched on/off electronically with low power consumption. Unlike past work reliant on additional bonding materials or liquid/gel couplant, this approach enables the receiver to be attached and detached at will, opening up the possibility of a simple charging pad for unmanned aerial vehicles (UAVs) or other consumer devices for harsh environment applications. Power transfer efficiency up to 63% was achieved, and the effect of varying steel plate thickness and clamping force was also investigated. A finite element model was also constructed to understand the vibration mode shape.