Vibration energy harvesting by hybrid electromagnetic-piezoelectric structure with dynamic buckling bistability

A hybrid vibration energy harvesting structure integrating electromagnetic and piezoelectric mechanisms is proposed. A buckling beam with magnets and two side magnets with springs are introduced. The harvester is small in size and simple in structure. It can efficiently harness vibration energy by exciting inter-well jumping over a broad frequency range. The harvester is composed of a buckling beam with a middle magnet, a set of coils, two symmetrical magnets with springs and a piezoelectric sheet. Under external excitations, the repulsive forces between the middle and side magnets drive the beam to undergo an inter-well motion, thereby generating electrical outputs through electromagnetic and piezoelectric effects. The dynamic coupling equations are derived, and the potential energy is obtained. Corresponding simulations are carried out for harmonic and random excitations. Finally, the validation experiments are conducted. The experimental results prove that the presented harvester can harness vibration energy efficiently, even under weak excitations and broadband excitations. At a random excitation of power spectral density of 0.06 g2/Hz, or the root mean square acceleration of 1.225 g, the generated electrical RMS power could exceed 27.09 mW.