Construction and Characterization of a Self-Triggered Piezoelectric Energy Harvester Using Rotation-Induced Swing of a Dangling Composite Beam

To offer an alternative solution for suffering from the inconvenience caused by centrifugal force or plucking mechanism in most existing piezoelectric rotational energy harvesters (PREHs), a self-triggered PREH using rotation-induced swing of a dangling composite beam is presented in this article. The unique characteristic of the novel PREH is the readily self-triggered working mode, neither requiring an extra trigger nor considering the effect of centrifugal force. To verify the proposed principle and find out the influences of relevant structural parameters on the dynamic behavior and power generation performance of the harvester, theoretical analysis, simulation, fabrication, and experimental validation are conducted. The results show that the inclination angle, proof mass, thickness, and length of the swinging beam exert significant influences on the output voltage of the harvester. First, the maximum output voltage is roughly increased with the rising inclination angle and decreasing length of the swinging beam, whereas the proof mass has a little effect on the maximum voltage. And there is an optimal beam thickness of 0.4 mm to maximize the generated voltage. Second, the optimal rotational speed corresponding to the maximum voltage is reduced with the decreasing beam thickness, increasing beam length and proof mass, but kindly immune to the varying inclination angle. Finally, a maximum output power of 3.6 mW is achieved with the optimal load resistance of 20
$\text{k}\Omega $
at 720 r/min as well as 18 blue light-emitting diodes (LEDs) could be lit by the self-triggered PREH.