Harvesting performance of quad-stable piezoelectric energy harvester: Modeling and experiment

To overcome the defects of bi-stable energy harvester (BEH) and improve the energy conversion ability under weak stochastic excitation, we developed a novel quad-stable energy harvester (QEH). This configuration is composed of a piezoelectric cantilever beam with a tip magnet and three external fixed magnets. By adjusting positions of the fixed magnets and altering the distances between the tip and the fixed magnets, four stable equilibrium positions (SEPs) can be realized in the static state of QEH. The diagram of potential energy illustrates that QEH has shallower and wider potential wells than BEH at the same separation distance, implying that it can execute jumping across the potential barrier easily. Validation experiment was carried out and the experimental results showed that QEH could create larger deflection and generate higher output voltage than BEH nearly over the whole range of excitation intensity. Furthermore, by controlling the gap and separation distances, the QEH can be optimized to reach the maximum output power for a certain excitation intensity.