Mechanical Energy Harvester With Ultralow Threshold Rectification Based on SSHI Nonlinear Technique

Harvesting energy from ambient sources has become of great importance these last few years. This can be explained not only by advances in microlectronics and energy harvesting technologies, but also by a growing industrial demand in wireless autonomous devices. In this field, piezoelectric elements offer outstanding performances, thanks to their high power density that makes them suitable for integrated microgenerators. However, such a domain still offers challenges to the research community. Particularly, embedding piezoelectric inserts as MEMS components raises the issue of low voltage output. Classical energy harvesting interfaces that feature bridge rectifier suffer from threshold voltage introduced by such discrete components, therefore compromising their use in real-life applications. In this paper is presented a new energy harvesting circuit that operates with ultralow voltage output, by the use of a magnetic voltage rectifier that does not present significant voltage gap. Experimental measurements performed on a simple transducer confirm theoretical predictions, and show that the proposed architecture operates well even for low-level vibrations, outperforming all known energy interfaces. Particularly, it is theoretically and experimentally shown that such an interface provides a gain greater than 50 compared to classical energy harvesting structures.