Optimization of the output power of a frequency-up conversion piezoelectric energy harvester

摘要

A mechanical stopper-based frequency up-conversion, FUC, piezoelectric energy harvester is designed for low frequency wideband vibrations. The primary low frequency beam is designed to have a resonance frequency as low as 15.6 Hz. Frequency up-conversion is achieved by a harvesting stopper beam which has a higher resonance frequency around 200 Hz. The effect of changing the impact point between the two beams is investigated by FEM simulations for further output power optimization. In case of using PVDF beams, the tip displacement of the stopper beam is increased from 13 μm to 32 μm when the length of the lateral overlap between the two beams is decreased from 50% to 3% of the stopper beam length for an input acceleration of 0.1g. This corresponds to a theoretical output open circuit voltage increase from 0.8V to 1.9V and a corresponding 6 times increase in the output power of the stopper beam. This proves the intuitive relationship between the effective stiffness of the two beams in the coupled vibrations phase and the position of the point of impact along the stopper.