Electrical optimization of power delivery through thick steel barriers using piezoelectric transducers

Abstract

In many commercial, industrial, and military applications, supplying power to electronics through a thick metallic barrier without compromising its structural integrity would provide tremendous advantages over many existing barrier-penetrating techniques. The Faraday shielding presented by thick metallic barriers prevents the use of electromagnetic power-transmission techniques. This work describes the electrical optimization of continuouswave power delivery through thick steel barriers using ultrasound. Ultrasonic channels are formed by attaching pairs of coaxially-aligned piezoelectric transducers to opposite sides of thick steel blocks. The thickness of the steel considered is on the order of, or greater than, one quarter wavelength of the acoustic power signal inside of steel, requiring the use of wave propagation theory to properly analyze the system. A characterization and optimization methodology is presented which measures the linear two-port electrical scattering parameters of the transducersteel-transducer channel. Using these measurements, the simultaneous conjugate impedance-matching conditions at both transducers are calculated, and electrical matching-networks are designed to optimize the power transfer from a 50Ω power amplifier on one side of the steel block to a 50Ω load on the opposite side. In addition, the impacts of, and interactions between, transducer and steel geometries are discussed, and some general guidelines for selecting their relationships are presented. Measurements of optimized systems using transducers designed to resonate at 1 MHz with diameters from 12.7 mm to 66.7 mm, and steel block thicknesses from 9.5 mm to 63.5 mm, reveal power transfer efficiencies as high as 55%, and linear delivery of 81 watts through an optimized channel.

A Review of Electric Impedance Matching Techniques for Piezoelectric Sensors, Actuators and Transducers

“…Piezoelectric ultrasound transducer being an electro-mechanical component is modeled as an equivalent circuit for the purpose of the EIMN design. The Mason [43], Redwood [44], KLM [45,46], network [32,47], and Butterworth-Van Dyke (BVD) [48] models are popularly used as equivalent circuits for a piezoelectric ultrasound transducer. The model is selected according to the application and system type like pulsed or continuous.…”

Analytical modeling of a sandwiched plate piezoelectric transformer-based acoustic-electric transmission channel

“…2. The optimal transmitting and receiving electrical port impedances, which minimize electrical power reflection at each frequency, were calculated across the entire characterized frequency range using the simultaneous conjugate matching technique presented in [1]. realizing an electrical network that could guarantee perfect impedance matching over this entire range would require a network of overwhelming complexity, so the statistical mean of the magnitude of the optimal port impedance data was selected as a static port impedance, because it was found to provide a reasonably strong match over the entire range.…”

“…The use of piezoelectric transducers can be very advantageous in many applications because the sPPT's formfactor can be kept small and energy conversion can be kept very efficient with careful material selection. many ultrasonic sPPT-based systems have been presented recently for power transmission [1]- [4], for data transmission [5]- [8], and for simultaneous power and data transmission [9]- [18].…”

“…To help mitigate this risk, many research groups have proposed wireless acoustic-electric transmission systems, recognizing that ultrasound propagates readily through elastic materials, including most metals. a variety of theoretical, analytical, and experimental ultrasound-based systems have been presented in the literature, using pairs of ultrasonic transducers to convert energy back and forth between the electrical and the mechanical domains [1]- [18].…”

Study on energy transmission through metal wall based on piezoelectric material

“…Using signal generator can generate electric signal, which can be converted into ultrasonic vibrations by the transducer because of the inverse piezoelectric effect and then the ultrasonic waves penetrate the solid metal wall [5]. Simultaneously, the acoustic mechanical vibration energy of the metal wall can be received and converted into electric energy by the piezoelectric transducers [6] because of the piezoelectric effect, which provides a means for wireless energy transformation.…”