Dynamics of Vibration Energy Harvester Governed by Gravity and Magnetic Force in a Rotating Wind Turbine Blade

This paper presents mathematical modeling of an energy harvester (EH) for a wireless structure health monitoring (SHM) system in wind turbine blades. The harvester consists of a piezoelectric energy harvester (PEH) beam, a gravity-induced disk, and magnets attached to both the beam and the disk. An electromechanical model of the proposed EH is developed using the energy method with repelling magnetic force considered. The three coupled equations — the motion of the disk, the vibration of the beam, and the voltage output — are derived and solved using ODE45 in MATLAB software. The result showed the blade rotation speed affects the output angular velocity of disk and the output PEH voltage. That is, as the blade speed increases, the disk angular velocity becomes nonlinear and chaotic which is more beneficial to generate larger power.