Underwater Communications based on Resonant Inductive Links

• Autor(a) principal: Ricardo Alexandre Coelho Magno
• Data de Publicação: 2018
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: https://hdl.handle.net/10216/114198
• topic: Engenharia electrotécnica, electrónica e informática; Electrical engineering, Electronic engineering, Information engineering

During more recent years there has been a considerable advancement in unmanned vehicles, more so in autonomous underwater vehicles, following the increasing interest in exploring unreachable parts of the ocean. Underwater autonomous work poses substantial obstacles when it comes to wirelessly charging the devices and most importantly to the monitoring of such operation, as well as the transfer of the data gathered. This thesis presents a solution for overseeing the parameters that come with the wireless charging of a system, repurposing the resonant inductive link to transmit bits of data in addition to the power transfer already in place. Furthermore, the work was developed on system designed with a high-voltage switching power driver, optimized for load resistance equal to 12.5 Ohm, having a resonance frequency of 240 kHz for a power transfer in the order of 80 W with a link efficiency up to 94%. The present work explores the substantial threshold of current available at the primary coil, from 0.5 A to 2.5 A with a variation of resistance from 1 Ohm to 11 Ohm seen at the secondary coil. This allows for a detection of different states which provide a wireless communication with a wide dynamic range. The overall efficiency of the link is not greatly affected by the different states necessary to transmit information. Knowing that the salinity value of the sea differs from region to region and in turn, both the levels of current and threshold are affected, it is possible to regulate the value of the resistance responsible for the load modulation to atone such difference, which makes for a system with a high level of modularity. This presents a simple and viable solution that is a clear alternative to the need of additional aftermarket circuits to monitor and assist the charging of devices underwater.