Experimental study of vibration modes switching based triple frequency-up converting energy harvesting with pre-biased displacement

In this study, a novel piezoelectric energy harvesting (PEH) system featuring triple frequency-up converting is proposed. The system comprises a piezoelectric cantilever and two stoppers. When in contact with the stoppers, the cantilever transitions into a high-order vibration mode, leading to the reversal of voltage outputs. The frequency-up converting effect is achieved by multiple mode switches occurring during a single cycle of motion. Experimental results demonstrated the significant ability of the proposed system to achieve triple frequency-up converting across a broad frequency range. Furthermore, three pre-bias displacements were introduced to assess the frequency-up converting characteristics of the PEH. The system exhibited a maximum ratio of triple and essential frequency components reaching up to 8.86. A maximum root-mean-square power output of 3.03 mW was achieved.