Characteristics of a nonlinear rotating piezoelectric energy harvester under variable rotating speeds

Abstract

This paper presents a nonlinear rotating vibration energy harvester by employing a piezoelectric cantilever beam and a nonlinear magnetic force due to a pair of magnets. A mathematical model is derived for the nonlinear rotating harvester based on the Lagrange's equation and the assumed-mode method, where piezoelectric coupling behavior is also included. From the model, the potential function of the nonlinear rotating harvester is firstly studied. Then its output characteristics under rotating speeds varying linearly and nonlinearly with time are carefully examined, respectively. The effects of the distance between the two magnets, the sweep rate, the sweep direction and the growth rate of the rotating speed on the output characteristics are investigated numerically. The simulation results reveal that all these parameters have strong influences on characteristics of the rotating harvester. When an optimal distance is achieved, a nonlinear rotating energy harvester is fit for low frequency and variable rotating motion more than a linear one. All conclusions will provide guidelines for designing nonlinear rotating vibration energy harvesters.