System for Wireless Charging of Battery-Powered Underwater Sensor Networks

Abstract

AHLUWALIA, URVI. System for Wireless Charging of Battery-Powered Underwater Sensor Networks. (Under the direction of Dr. Zeljko Pantic).Wireless Power Transfer (WPT) systems have recently gained popularity in delivering energy underwater. Existing solutions that employ conductive charging by wet-mate connectors are costly, with complicated mating and maintenance requirements. WPT systems overcome these challenges by avoiding expensive material and complex mating mechanisms, thus making them viable alternatives.This thesis proposes an energy delivery system for wireless charging of battery-powered underwater sensor networks. Using ROVs and AUVs for periodic wireless recharging of deployed batteries, this system can increase the lifetime of such a sensor network. This thesis provides a background establishing the importance of recharging underwater sensor networks and the various challenges associated with this task. FEM-based procedures are used to design and optimize a wireless charging system and magnetic coupler, and system losses are calculated using an analytical model. The proposed system was evaluated using a prototype and provided experimental results for coils submerged in water at salinity levels similar to fresh and sea waters. These results were also compared with coils in air.The developed prototype, when operated at 50 W, worked at a maximum efficiency of 90% with coils submerged in seawater medium, with minimum possible gap, and an output voltage of 15.6 V. The experiments also show that the prototype can nominally deliver 50 W of power at 85% efficiency for a coil gap of 4 mm, 12.9 V output voltage in seawater salinity.Under similar conditions, the system has the worst-case efficiency of 77% when the coils are 12 mm apart.

Wireless Power Transfer for Unmanned Underwater Vehicles: Technologies, Challenges and Applications

“…For instance, in [118], the authors were able to conduct laboratory tests with a power transfer of approximately 1 MW for a ship charging application, with its subsequent installation on the Norwegian ferry MS Folgefonn. In the marine environment, many inductive charger prototypes have been tested for underwater recharging of AUVs [119][120][121][122][123][124][125][126][127][128][129] and underwater sensors [130][131][132][133][134][135][136][137]. These charging devices are generally installed in sub-sea docking stations.…”