Circuit nonlinearity effect on the performance of an electromagnetic energy harvester-structure system

Scavenging energy from structural vibration requires an efficient energy harvesting circuit which could introduce nonlinearity into the harvester-structure system. This study examines the performance of a linear structure equipped with an Electromagnetic (EM) energy harvester connected to a nonlinear standard energy harvesting circuit (SEHC) consisting of a full-wave bridge rectifier and a capacitor in parallel with a resistor. To facilitate the understanding of the nonlinear circuit effect on the behavior of the coupled harvester-structure system under sinusoidal excitation, a first-order harmonic balance approximation method is employed. Numerical simulation and experimental study are conducted to validate the accuracy of the proposed approximation method. Results suggest that the blockage effect of diodes in the bridge rectifier in the SEHC should be reduced by using diodes with small voltage drop value or by designing an EM energy harvester with large electromechanical coupling coefficient to improve the vibration mitigation performance and to enhance the optimal energy harvesting capability of the EM energy harvester. Results also show that circuit nonlinearity should be considered in order to estimate the response of the system accurately.