Magnetically coupled dual-beam energy harvester: Benefit and trade-off

This article investigates a dual-beam vibration energy harvester in which two piezoelectric cantilever beams are coupled by magnets. The analytical solution of such a vibration energy harvester system is derived. The dynamic responses and energy harvesting performances in quasi-linear, monostable and bistable regions are evaluated. With the analytical model validated by numerical simulation, a comprehensive parametric analysis is conducted to evaluate the effects of base excitation, ratio of natural frequencies and electromechanical coupling, revealing the benefits and limitations of the dual-beam vibration energy harvester, which was not possible before without the analytical tool. The magnetic interaction provides the nonlinearity and can achieve high-energy oscillations for both beams at the same time for power enhancement. However, the analysis also ascertains that the trade-off between the dual beams should be made given the change of base excitation, ratio of natural frequencies and electromechanical coupling. For a certain range of excitation, the increased output of one beam is always accompanied by the decreased output of the other for the high-energy oscillations in both monostable and bistable configurations. By and large, the operational bandwidth is enlarged for both beams owing to the co-occurrence of high-energy oscillations of the dual beams, while the performance of the system as a whole is somewhat restricted by the trade-off.