Broadband spring-connected bi-stable piezoelectric vibration energy harvester with variable potential barrier

To improve the harvesting performance of bi-stable energy harvesters, this paper proposes a novel bi-stable piezoelectric energy harvester which consists of a piezoelectric cantilever beam with a tip magnet and a movable magnet. The movable magnet connects to the base through a spring and is allowed to move along the spring compression direction. The nonlinear distributed parameters dimensionless mathematic model of the harvester is derived based on Hamilton’s principle. The effects of excitation amplitude, excitation frequency, spring stiffness and Gaussian white noise on harvesting performance are analyzed by applying bifurcation diagram, phase trajectory, Poincare map and power output. The numerical simulations show that the proposed energy harvesting system reduces the potential barrier and makes the snap-through motion easier. It is demonstrated that the proposed energy harvester provides wider bandwidth and higher efficiency than the typical bi-stable energy harvester when subjected to low excitation amplitudes or low excitation frequencies.