Date of Publication :23rd February 2018

Abstract: The use of piezoelectric materials to transform mechanical energy into electrical energy is not a recent idea. In action, however, piezoelectric electrical generators remain limited to a very low power domain, typically within or below the mill watt range. This is mainly due to the mechanical properties of piezoelectric materials: they accept very high stresses but their strains are very small, making it difficult to use large quantities of material. Another argument concerns the high mechanical frequencies required for the efficient use of these materials: ambient mechanical vibrations usually remain within the range of 0.1–1 kHz, while piezoelectric materials that operate up to hundreds of kilohertz. A dramatic reduction in the consumption of integrated circuits linked to the development of mobile electronic devices has been achieved in recent years, enabling the use of ambient energy instead of batteries. The emphasis here is on the transformation of ambient mechanical vibrations into electrical energy. This paper compares the output of a vibration-powered electrical generator using PZT piezoelectric ceramics connected with two different electrical circuits. A new approach to piezoelectric power conversion based on nonlinear voltage processing is proposed and implemented using a different circuit. Theoretical predictions and experimental results show that the new technique can increase the power harvested by a factor of up to 4 compared to the standard technique. In particular, the problem of power optimization is examined in the case of broadband, random vibrations.

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