A tunable frequency up-conversion wideband piezoelectric vibration energy harvester for low-frequency variable environment using a novel impact- and rope-driven hybrid mechanism

This paper presents a tunable frequency up-conversion wideband piezoelectric vibration energy harvester using a novel impact- and rope-driven hybrid mechanism, in which a high frequency generating beam is triggered by the rope or impacted directly by the low frequency driving beam. A mass-spring-damper equivalent model was built to understand the operation mechanism of the proposed piezoelectric vibration energy harvester. Based on the theoretical model, the effect of the rope-margin on the performance of the proposed piezoelectric vibration energy harvester was numerically analyzed. Both the simulation and experimental results showed that the central working frequency of the proposed piezoelectric vibration energy harvester can be changed easily from 74.75 Hz to 106 Hz by adjusting the rope-margin from 0.5 mm to 2 mm without any structure re-fabrication. Moreover, a bandwidth 4.2 times wider than the conventional frequency up-conversion piezoelectric vibration energy harvester based on impact-driven mechanism can be achieved. The tunable performance of the proposed piezoelectric vibration energy harvester system make it promising for vibration energy harvesting in wideband environments with low frequency.