Modeling and analysis of magnetically coupled piezoelectric dual beam with an annular potential energy function for broadband vibration energy harvesting

Conventional piezoelectric cantilever-based vibration energy harvesters have narrow bandwidth. In this article, we develop a dual-beam piezoelectric energy harvester featuring an annular potential energy function that can harvest vibration energy over a wide spectrum under small amplitude excitations. The proposed harvester contains two conventional piezoelectric cantilevers placed orthogonal to each other which are coupled by repulsive magnetic force. We demonstrate analytically and numerically that a new annular potential energy function can be built with proper configuration. In the new annular stable state, the harvester can detour around the potential barrier rather than jump over it, yielding large amplitude voltage outputs throughout a wide spectrum. Case studies were carried out, and it is proved that the proposed annular stable harvester has a bandwidth of 3.9 Hz and a voltage output performance 3.01 times better than that of a conventional bistable one under excitations of 3 m/s². The nonlinear dynamics of the proposed harvester are analyzed in detail.