Comparative investigation and nonlinear characterization of multi-stable electromagnetic vibration energy harvesters

The nonlinear characterization of the response of a multi-stable electromagnetic vibration energy harvester is performed. By applying an initial compression to the harvester’s supporting springs, a geometrical nonlinearity develops and can transition the system through mono-stable, bi-stable, and tri-stable configurations based on the geometrical parameters. Considering a low frequency design criterion for the multi-stable energy harvester, the dynamics and effectiveness of the mono-, bi-, and tri-stable harvester is studied individually for up- and down-swept excitations considering the influence of the damping ratio and excitation amplitude on the system’s dynamics. Furthermore, this study introduces a novel methodology for configuring the harvester to specifically capture a predetermined range of frequencies, determined by the selection of the linearized frequency of the nonlinear system. A comparative study is carried out among the three harvesters’ configurations as well. It is demonstrated that the effectiveness and dynamics of bi-stable and tri-stable energy harvesting systems are strongly dependent on the input excitation and damping. This is due to the existence of intra-well and inter-well motions and hence the overall system’s dynamics change. The results of the comparisons demonstrate that the tri-stable harvester has great advantage in ultra-low frequencies due to the chaotic inter-well motion of the system. However, this tri-stable design is strongly dependent on several factors that may result in low performance due to the intra-well motion.