A single-magnet nonlinear piezoelectric converter for enhanced energy harvesting from random vibrations

AbstractPower harvesters from mechanical vibrations are commonly linear mechanical resonators that are most efficient when excited at resonance. Differently, under wideband vibrations, linear converters are suboptimal. A nonlinear converter is here proposed that implements nonlinearity and bistability by employing one external magnet, in order to improve conversion effectiveness while simplifying device fabrication. The converter is composed of a piezoelectric bimorph on a ferromagnetic cantilever which, under proper coupling with the external magnet, bounces between two stable states when excited by random vibrations. According to theoretical predictions, experimental results demonstrate a remarkable improvement of the rms voltage generated by the converter when bistable behaviour is present