Exploring the advantages of acoustic power transfer using 1-3 composite transducers

Konferenz: MikroSystemTechnik Kongress 2021 - Kongress
08.11.2021 - 10.11.2021 in Stuttgart-Ludwigsburg, Deutschland

Tagungsband: MikroSystemTechnik Kongress 2021

Seiten: 4Sprache: EnglischTyp: PDF

Kar, Bibhu; Wallrabe, Ulrike (Laboratory for Microactuators, IMTEK – Department of Microsystems Engineering, University of Freiburg, Germany)

In this paper, we present an efficient system capable of transmitting electrical energy wirelessly through a metal wall using acoustic waves. We investigated the suitability of 1-3 composite piezoelectric transducers and compared the results to commonly used hard PZT disc transducers. Our power transfer system used a 20 mm thick Aluminium wall as a transmitting medium and a pair of transducers glued coaxially to either side for generating and receiving acoustic waves. We quantified the transferred electric power in terms of the electric load attached to the receiver. We present resistive and resistive-inductive loading conditions for maximum power transfer. The predictions based on a KLM model agreed well with the measurement and showed a significant enhancement in the power transfer efficiency with optimal resistive-reactive loading. We further find that the 1-3 composite piezoelectric transducers give higher efficiency due to their lower acoustic impedance mismatch with Aluminium, compensating for higher material losses.