Design and investigation of an enhanced magneto-mechanical nonlinear energy harvester

In this work, a unique magneto-mechanical energy harvester is fabricated, modeled, and investigated. The magneto-mechanical energy harvester consists of a levitated magnet, forming a magnetic spring, connected to oblique, mechanical springs. Upon base-excitation, the levitated magnet experiences nonlinear forces in the direction of motion due to the mechanical and magnetic spring. Voltage is induced in a coil placed around the body of the energy harvester. Results confirm the oblique, mechanical springs and magnetic springs introduce geometric negative and hardening stiffnesses. This behavior allows for the use of disc magnets instead of ring magnets, reducing energy dissipation due to Coulomb damping. Forward and reverse sinusoidal frequency sweep measurements at a constant acceleration of 0.75g shows the characteristic backbone curve exhibited by Duffing-type nonlinear oscillators. The frequency response of the proposed device demonstrates the broadband capabilities with a measured peak power of approximately 7-mW at 15Hz. Results from the model are in good agreement with data obtained from the experiment.