Discontinuous Dynamics of a Frequency Up-Conversion Piezoelectric Harvester With an Impact Controlling Mechanism

In this study, an impact based frequency up-conversion mechanism is studied using discontinuous dynamics theory. The mechanism consists of a sinusoidal vibrating plastic beam as a driving element and a piezoelectric bimorph as a generator. In order to remove the unfavorable stick motion and enhance the performance of the energy harvester, two pairs of racks and pinion gears and a slider-crank have been added to the system, which makes us able to control the impact occurring time between the driving beam and the generator. In this work, the Rayleigh-Ritz method was applied to obtain the distributed-parameter models of the driving beam and the piezoelectric generator. Both the forward and the backward mechanical-electrical coupling effects were considered during the modeling of the generator. The electrical and mechanical dynamic behaviors of the proposed piezoelectric energy harvester were analytically studied to better understand the effect of system parameters on the performance of piezoelectric energy harvester. Discontinuous dynamics theory was applied to obtain the generated power and voltage. The stability of the periodic solutions was obtained, and the bifurcation diagrams of displacements, impact velocities, generated power, and voltage were obtained analytically as the excitation frequency varying.