Systematic study of dual resonant rectilinear-to-rotary motion converter for low frequency vibrational energy harvesting

Vibrational energy harvesting of environment has been an intensive research field in recent years, but there are still some challenges regarding low frequency applications. Building off our previous invention of a non-contact electromagnetic harvester which converts rectilinear motions into rotary oscillations, this paper establishes the theoretical model of the dual resonator and systematically analyzes the model through numerical simulations and experiments, and further understands the relationship of key design parameters and to optimize the harvester's performance. Nine different repulsive magnet configurations are studied to verify that the electromechanical model can precisely describe the dynamic mechanism of the broadband multi-stable energy harvester. Numerical simulations and experiments are performed at different harmonic excitation levels ranging from 2 to 14 Hz and show a good agreement. Research shows that the output energy flow relies on the three dynamic oscillation patterns of the rotor, corresponding to the potential energy, which change due to different repulsive magnetic configurations, preset angles, and excitation levels. Frequency up-conversion is achieved when the rotor is plucked by the driving arc magnets at a low frequency (5 Hz) and transformed to a higher frequency (30 Hz). The optimized dual resonator's main advantage over the original dual resonator is a widened the bandwidth (20% increase) and a larger power output (69% increase) in comparison with our previously reported prototype. (C) 2018 Elsevier B.V. All rights reserved.