Piezoelectric stacks to increase the transmitted power of acoustic power transfer through metal walls

Abstract

Acoustic power transfer is a wireless power transfer technology that enables to supply sensors placed behind metal walls by using acoustic waves generated by piezoelectric transducers positioned on both sides of the wall. The state of the art reports that high levels of powers, up to hundreds of watts, can be transmitted but at the cost of high input voltage levels, making the control electronics complicated, low-efficient and even hazardous. In this paper, we study and validate experimentally the use a piezoelectric stack to generate the acoustic waves to transmit high power levels with low actuation voltages. By using a stack of four piezoelectric disks, the transmitted power is multiplied by 5 compared to a single disk for the same excitation voltage, and the power density is multiplied by 2, reaching 8.2 mW/V2/cm3.