Design of a disk-swing driven piezoelectric energy harvester for slow rotary system application

This paper presents mathematical modelling of an energy harvester that converts slow mechanical rotation into piezoelectric vibration using a small disk and a pair of magnets, for large-scale machinery monitoring applications such as wind turbine blades. The harvester consists of a piezoelectric cantilevered beam, a gravity-induced disk, and magnets attached to both the beam and the disk. The energy method is used to derive the three coupled equations that describe the motion of the disk, the vibration of the beam, and the harvester voltage output. The equations are solved using ODE45 in MATLAB software and verified by the corresponding experimental study. The result shows varied energy harvesting performance by blade rotational speed. At low blade speed, the harvester generates power by regularized magnetic excitation per blade revolution. At high blade speed, however, the disk behavior becomes chaotic to increase excitation force and power generation. The results show that the model can quantify power as a function of blade speed, and the proposed harvester can generate a considerable amount of power for self-sustainable sensing and monitoring of wind turbine blades.