Nonlinear arbitrary-directional broadband piezoelectric vibration energy harvester using 3-DOF parallel mechanism

Abstract

Overcoming the disadvantages of direction selectivity and narrow bandwidth are two key problems to improve the efficiency of energy harvesting from ambient vibration, and also the premises of the practical application of the piezoelectric vibration energy harvester. In this paper, utilizing a 3-DOF parallel mechanism and nonlinear magnetic forces generated by polar opposing magnets, a nonlinear piezoelectric vibration energy harvester is proposed and explored. The kinematic equation, the governing equation of motion, and the piezoelectric coupling equation of the vibration energy harvester are established. On this basis, through numerical simulation, the normal modes of the vibration energy harvester in linear case are explored, the effect of the polar opposing magnets and the nonlinear characteristics are analyzed, the 8 potential wells in three-dimensional space of the vibration energy harvester are investigated, and the motion trajectories of the octuplet stable system are estimated. Then, the developed vibration energy harvester is tested with vibration excitation along different directions and sweep excitations. The results show that the developed vibration energy harvester can harvest vibration energy along any directions, and its bandwidth is extended by introducing magnets. The maximum average power of the developed vibration energy harvester is 22.3 mw for 1 g excitation, and the bandwidth is about 5.5 Hz with its center frequency around 11 Hz. This work proves that using parallel mechanism with nonlinearity is a promising solution to realize arbitrary-directional vibration energy harvester with wide bandwidth.