A class of piezoelectric-based rotary electrical-energy generator is presented in which a polygon-shaped gear is used to effectively couple the rotating shaft with multiple piezoelectric cantilevers. The relation between the input rotational speed and the output power production for a laboratory-scale device with an octagonal gear is systematically characterized both by experiments with DC-motor controlled rotation inputs and by finite-element analyses (FEA) with prescribed gear rotational speeds. The electric signals generated by each piezoelectric bimorph are shown in phase with each other as well as the total power output scales with the number of piezoelectric bimorphs. The generator outputs higher electric power over a significantly wider range of rotational frequencies than similar devices do using the piezoelectric transduction mechanism. The generated power increases almost linearly with the input rotational speed for input frequencies up to at least 300 RPM. The broadband feature of the present generator makes it ideal for power generation systems that operate with low frequent, broadband excitations like those that harvest energy from wind and tidal flows.
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