Experimental analysis of optimized impact interval/vibration period ratio on piezoelectric energy harvesting

This paper proposes and tests an impact-excited piezoelectric energy harvester, which converts human kinetic energy into electrical energy. While the impulses between the ridges and the proof mass lead the piezoelectric bimorph vibrating at its resonant frequency with decaying amplitude, sequent and reasonable impulses provide higher generating electrical energy. The research described herein highlights the effect of the impact interval/vibration period ratio on the energy conversion of the aforementioned harvester. The interval between consecutive impulses, Δt_i, with respect to the space distance between the two ridges, Δd, and the vibration period, T, are analyzed. The fabricated prototypes provide various Δt_i/T that can be investigated for their effect on output performance. A series of experiments demonstrate that output power is reduced by 48% with a longer interval and by 27% with a shorter interval compared to the optimized design.