Modeling and harmonic analysis of energy extracting performance of a piezoelectric nonlinear energy sink system with AC and DC interface circuits

Abstract

Nonlinear energy sink (NES) has been successfully integrated with vibration energy harvesters to enhance energy extracting performance in a broadband manner. This article intends to evaluate a piezoelectric energy harvester based on the NES technique and coupled to a pure resistive load (EHNES-AC) and a standard rectifying energy extracting circuit (EHNES-DC) under harmonic excitation. A new approach for the analysis of the EHNES-DC system is proposed by simplifying the DC circuit on the basis of the equivalent impedance method (EIM). The theoretical solutions and analyses of the EHNES-AC system, the EHNES-DC system with an original DC circuit based on Shockley diode model and the EHNES-DC system with a simplified DC circuit based on EIM are then derived by the harmonic balance method (HBM). On the other hand, the holistic circuit simulation is performed by employing the equivalent circuit model (ECM) to validate those approximate theoretical analyses. With the assistance of the proposed models and simulation tool, the effect of the load resistance on the efficiencies of the EHNES-AC and EHNES-DC systems is parametrically studied. Experiments are also conducted and verify the main conclusions given by theoretical and numerical studies.