Modeling a Wave Energy Harvester for Supplying Data Buoys

An energy harvester scavenging the kinetic energy of fluctuating waves for supplying small sea monitoring buoys is studied and tested. The harvester exploits a magnetic cylinder that rolls on a track due to the pitching motion of the buoy. The electromagnetic coupling between the rolling magnet and pairs of coils placed along the track generates an electromotive force used to supply a DC load through a bridge rectifier. The considered harvester is characterized by low-cost, simplicity, lightness and efficiency. An analytical model of the harvester is presented to investigate its operating conditions and to predict its nonlinear dynamic behavior. The operating mode of the energy harvester named bang-bang is studied in depth as it allows maximizing the extracted power, and analytical equations that characterize the behavior of the harvester in this operating mode are deduced. A prototype of the energy harvester was built and tested in order to identify the model parameters and to validate the theoretical results.