Theoretical and experimental studies on the characteristics of a tri-stable piezoelectric harvester

In this paper, we study the characteristics of a tri-stable energy harvester (TEH) that is realized by the effect of magnetic attractive forces. The electromechanical model is established, and the corresponding coupling equations are derived by Euler-Lagrange equation. The potential energy indicates that the TEH's potential well depths are the determinant factors for performance and can be designed such that the snap-through is easy to be elicited. We find that the TEH exhibits the best performance when the three potential well's depths are nearly identical. To highlight the advantage of the TEH in harvesting energy, the comparisons between the tri-stable energy harvester and the bi-stable energy harvester (BEH) are carried out in simulations and experiments. The results prove that the TEH is preferable to the BEH in energy harvesting. The validation experiments show that the TEH owns a wide range of frequency of snap-through and high output voltage.