Elaboration and characterization of a low frequency and wideband piezoceramic generator for energy harvesting

The aim of this work was to efficiently convert the mechanical vibrations into electrical energy by using direct piezoelectric effect. Most mechanical vibrations occur at low frequencies varying from 50 to 120 Hz. As piezoelectric converters provide maximum energy conversion when their natural frequencies are close to the frequency of the mechanical source, it would be interesting to design piezoelectric converters operating at low resonance frequencies. For those reasons, a piezoelectric generator has been developed with multi-cantilever piezoceramics operating at low frequencies. The device was shaped using the tape casting technique followed by a laser cutting process. It was made of six piezoelectric cantilevers with different lengths and various masses at their free-ends. Its piezoelectric response was characterized and analysed. It was shown that it can operate at low and many resonant frequencies. Moreover the frequency bandwidth was widened up to 200% compared to the one obtained from a single cantilever beam. It allowed efficiently exploiting mechanical vibrations of sources exhibiting wide frequency spectrum.