Characteristics and comparative analysis of piezoelectric-electromagnetic energy harvesters from vortex-induced oscillations

The vortex-induced vibrations of a circular cylinder attached as a tip mass at the end of a cantilever beam are investigated for hybrid energy harvesting using two different transduction mechanisms, namely piezoelectric and electromagnetic. The high aeroelastic oscillations generated for a range of wind speeds are translated into electrical energy by both transducers. The aerodynamic force is modeled by a modified van der Pol wake oscillator model. The Euler–Lagrange principle and Galerkin procedure are utilized to develop a nonlinear distributed-parameter model to evaluate performance of the hybrid energy harvester. The effects of the external load resistances, placement and mass of the magnet on coupled damping, frequency, and performance of the hybrid energy harvester are deeply studied. It is shown that performance of the hybrid energy harvester is highly dependent on both the external load resistances. It is demonstrated that, in the synchronous region, placement of the magnet has a huge effect on tip displacement of the harvester, generated current in the electromagnetic circuit, and generated voltage in the piezoelectric circuit. On the contrary, mass of the magnet has a negligible effect on behavior of the considered hybrid system. A comparative study between the hybrid energy harvester with the classical piezoelectric and electromagnetic counterparts is also carried out. It is indicated that, by carefully choosing the external load resistances and harvesters' properties, energy harvesting in a hybrid configuration is an effective replacement for two different classical harvesters working separately. It is concluded that hybrid energy harvesters come out to be an effective choice for powering multiple electronic devices.