An Ultrasonic Through-Metal-Wall Power Transfer System with Regulated DC Output

Portable through-metal ultrasonic power transfer using a dry-coupled detachable transmitter

Ultrasonic waves can be used to transfer power and data efficiently through metallic enclosures when feedthroughs are not practical due to structural or electromagnetic shielding considerations. Previous implementations of ultrasonic power transfer (UPT) used a piezoelectric transducer permanently bonded to the metal for efficient ultrasonic coupling. For portable operation, it is essential to have a detachable transmitter (charger) that is only attached to the enclosure while transferring power. This requirement presents several design challenges; notably, detachable ultrasonic coupling typically relies on liquid or gel couplant, which may become inconvenient or less robust during repeated attachment and detachment. Thus, this work develops a dry-coupled detachable UPT system to transfer power efficiently through a metallic enclosure without the need for a liquid couplant. Low attenuation soft elastomers are experimentally tested with a magnetic setup to evaluate their dry-coupled efficiency. Samples with different materials and thicknesses are experimentally tested to select the best configuration for dry ultrasonic coupling. The softest elastomer tested yielded the best ultrasonic efficiency (AC-to-AC) of 68% at 1 MHz. A full DC-to-DC portable (battery-operated) UPT system was then developed and experimentally characterized. The system was capable of delivering up to 3 W of DC power to a resistive load with a total efficiency of 50%.

An Optimal Design Method for Improving the Efficiency of Ultrasonic Wireless Power Transmission during Communication

Due to the excellent directivity, strong penetrability, and no electromagnetic shielding effect, ultrasonic waves have good potential for wireless energy transmission and information transfer inside and outside of sealed metal devices. However, traditional ultrasonic based energy transmission methods usually result in considerable energy consumption because of the impedance mismatch during the impedance modulation of the communication. This paper presents an optimal design method for efficient energy transfer during ultrasonic communication. The channel equivalent circuit model is established by only using the acoustic-electric channel scattering parameters. According to the equivalent circuit model, the channel impedance matches with a weak mismatch state is performed during the communication. In this way, the impedance modulation effect is ensured with a lower decrease in the energy transmission efficiency. Finally, the simultaneous energy transmission and impedance modulation are carried out through the 11 mm thick 304 stainless steel plate. The transmission power is 37.86 W with a transmission efficiency of 45.75%, and the modulation rate is 10 Kbps. Compared with the traditional methods, our proposed energy transmission efficiency is increased by 17.62%. The results verify the proposed method's effectiveness and the high accuracy of the model. The proposed method has great engineering applications and broad prospects in condition monitoring of metallic environments.

State-Space Model of an Electro-Mechanical-Acoustic Contactless Energy Transfer System Based on Multiphysics Networks

Contactless energy transfer systems are mainly divided into acoustic, inductive, capacitive, and optical, in which main applications are related to biomedical, wireless chargers, and sensors in metal enclosures. When solids are used as transfer media, ultrasound transducers based on piezoelectricity can be used for through-wall power transfer, which can be named as an electro-mechanical-acoustic contactless energy transfer system. This work presents a state-space model derived from a multiphysics network that includes all the multiphysical power conversion without separating the stages and including the real physical elements, like as the piezoelectric parameters and the geometry of the transfer media. The model is compared to the experimental response of the system and evaluated for different scenarios regarding transducers types and solid transfer media. An error analysis has shown that the maximum quadratic error between theoretical and experimental responses is 3.7%.