Harvesting Weak Ocean Current Energy for Resident Unmanned Underwater Vehicles

A weak ocean current energy harvester is designed to power resident unmanned underwater vehicles and in-situ instruments for adaptive seafloor observation. The seawater kinetic energy is harvested by current turbines and converted into rotating mechanical energy, which is transmitted to a direct-drive disk-type permanent magnet synchronous electric power generator by noncontact magnetic couplings and converted into electrical energy by the electrical power generator. Parameters of the weak ocean current energy harvester are simulated and optimized to guarantee the optimal energy efficiency. The torque transmission performances of the magnetic couplings are verified on an experiment platform. Characteristics of the electric power generator are simulated by three dimensional finite element method (3D FEM) and tested in laboratory experiment. Underwater experiment results prove that the proposed weak ocean current energy harvester can operate and output 2.8W electricity steadily at an ocean current velocity as low as 0.4m/s.