Synchronized Switch Harvesting on ElectroMagnetic System: a nonlinear technique for hybrid energy harvesting based on active inductance

Abstract

This paper proposes a hybrid nonlinear interface combining both piezoelectric and electromagnetic effects for energy harvesting purposes. Based on the previously developed Synchronized Switch Harvesting on Inductor (SSHI) scheme, this technique aims at including as much as electroactive parts as possible, thus advantageously replacing the passive inductance in the SSHI approach by an electromagnetic transducer. The proposed scheme, called Synchronized Switch Harvesting on ElectroMagnetic system (SSH-EM) results in a significant increase of the output voltage, thus leading to a consequential increase of the harvested power, especially in the case of low-coupled systems, when compared to the classical SSHI approach and the standard approach (i.e., directly connecting the piezoelectric element to the load through a diode bridge rectifier and a smoothing capacitor). The working principle, along with theoretical developments, and supporting experimental results, are presented, both considering structures featuring constant displacement magnitude or structures driven at their resonance frequency with a constant excitation magnitude.