A high performance system for wireless transmission of power and data through solid metal enclosures

Traditionally, when electrical signals need to be transmitted through sealed metal enclosures, penetrations are introduced to enable wire feed-throughs. These penetrations can compromise the structural integrity of, and environmental isolation provided by, the enclosure. This thesis presents a high-performance wireless system capable of transmitting both power and data through a metal barrier simultaneously, using only ultrasound, thereby eliminating the need for barrier penetrations. First, the underlying principles and phenomena governing the behavior of a wireless, piezoelectric transducer-based acoustic-electric transmission channel, and general channel design considerations are discussed. Second, a design methodology is presented for optimizing the power transfer efficiency of an acoustic-electric power transmission channel using simultaneous two-port conjugate impedance matching, a hardware architecture is proposed for continuous-wave power delivery, and the measured power transmission capabilities of two separate power links are reported. Third, a data transmission link architecture is presented which utilizes orthogonal frequencydivision multiplexing (OFDM) in order to achieve a high spectral efficiency in the presence of a very frequency-selective acoustic-electric channel. The data link is optimized using a bit-loading scheme with phase-shift keying (PSK), and the adoption of quadrature amplitude modulation (QAM) and a power-loading scheme are considered as methods for improving the link's overall throughput. Fourth, a system is presented which uses a power and data transmission link in close proximity on a single metal barrier, and utilizes sharp filtering and a power-data link synchronization technique to completely eliminate interference in the data link caused by power-to-data channel signal leakage. Measurements of this system show that it can simultaneously transfer 32.5 W of AC power and transmit data at 12.4 Mbps through a 63.5 mm thick block of submarine steel. Finally, an accurate enhanced one-dimensional mathematical model of the acoustic-electric channel is presented which allows a designer to quickly and easily predict the performance capabilities of a power or data transmission link and explore the impacts of many design parameters on a channel's response without needing to physically build or test the channel. This work illustrates that ultrasonic through-metal transmission systems can achieve much higher power transfer efficiencies and data throughputs than previously thought possible, and also that both power and data links can be implemented on a metal enclosure simultaneously, without significantly impacting each others' performance.