Mechanical effect of combined piezoelectric and electromagnetic energy harvesting

Abstract

The recent progress in microelectronics, combined with the increasing demand from numerous industrial fields in terms of autonomous sensor networks, has placed a particular attention on ways to power up such devices. In order to bypass the drawbacks of batteries, harvesting power from ambient sources has been proposed. Among all the available sources, particular attention has been placed on scavenging energy from vibrations, which are commonly available in many environments. In this case, converting mechanical energy into electrical energy is typically done using either piezoelectric or electromagnetic transduction. Recently, the combination of these two conversion mechanisms has been proposed, allowing benifits from the advantages of the two techniques and leading to the concept of hybrid energy harvesting. This paper proposes an investigation of the combination of the two conversion effects on the mechanical behavior of the host structure, both in terms of damping and stiffness changes. Particularly, for highly coupled, weakly damped systems, it is shown that combining the piezoelectric and electromagnetic effects does not lead to a power increase, but allows enhancing both the bandwidth and the load independency of the harvester.