Materials, structures and power interfaces for efficient piezoelectric energy harvesting

The possibility of recycling ambient energies with miniature electrical generators instead of using batteries with limited lifespan has stimulated important research efforts over the past years. Integration of such miniature generators is mainly envisioned into low power autonomous systems, for various industrial or domestic applications. This paper focuses on the use of piezoelectric materials for generating electrical energy from ambient mechanical vibrations. A review of the piezoelectric materials and the electromechanical structures which have been proposed in this field is first presented. Electrical circuits with one-stage, two-stage and three-stage interfaces which have been developed for optimizing the electrical power flow from piezoelectric devices to energy storage elements are then compared to a novel technique for controlling the energy converted by piezoelectric materials. This novel approach is derived from Ericsson thermodynamic cycle. A solution for practical implementation is proposed, theoretical predictions and experimental results are compared and discussed.