An optimized energy harvester for moving mass induced vibration

Abstract

This paper presents a piezoelectric energy harvester by which the vibration energy induced by a moving mass is converted to electrical energy through the piezoelectric effect. An electromechanically coupled finite element model (FEM) based on the Euler-Bernoulli beam theory is employed to estimate the electrical energy that can be generated by the energy harvester. The effects of mass ratio, beam length, travel time and load resistance on the energy output are examined. Experiments are conducted to verify the numerical model. The experimental results are in good agreement with the numerical prediction. In the design stage, the nonlinear conjugate gradient (CG) algorithm is applied for the calculation to maximize the energy throughput from the energy harvester. Results have shown that the harvested energy depends heavily upon the optimal choice of load resistance and travel time of the moving mass. In addition, the longer the beam or the higher the mass ratio, the higher the energy throughput that can be achieved.