System-Level DC-to-DC Analysis and Experiments of Ultrasonic Power Transfer Through Metallic Barriers

Ultrasonic waves can be used to transfer power through sealed metallic enclosures when feedthrough wires are not a viable or desirable option. In this work, we present a complete system-level investigation of ultrasonic power transfer through metallic barriers via detailed experiments, analytical modeling, and numerical simulations for analyzing and predicting the dc-to-dc performance. A Class E amplifier design is tightly integrated with the ultrasonic system to excite it efficiently, and a full-bridge rectifier converts its output to dc. A 1-D transfer matrix model was used to model the ultrasonic system, and a harmonic balance analysis simulated the coupled response, including the driving and rectifying electronics. The analytical results are compared to numerical simulations using the finite element method and experimental measurements. The developed system achieves an 83% ac-to-ac efficiency through a 3 mm aluminum barrier while operating at 1 MHz. The system's overall dc-to-dc efficiency peaked at 68% while delivering 17.5 W to a dc load.