Wind energy harvesting from a magnetically coupled piezoelectric bimorph cantilever array based on a dynamic magneto-piezo-elastic structure

This paper presents a novel wind energy harvester based on a magneto-piezo-elastic structure using a magnetically coupled piezoelectric bimorph cantilever. The harvester consists of a power-generating stator for the piezoelectrics and a wind-powered rotor and Savonius blades. A permanent magnet on the free-end-tip mass of the vertically aligned piezoelectric bimorph cantilever interacts with a rotating counterpart permanent magnet affixed onto the top disk plate of the Savonius rotor. Its operating principle provides a better understanding of the magneto-piezo-elastic energy conversion. A good arrangement of permanent magnets was demonstrated to be effective for a reduction of the resistance torque to approximately 94.6 mN center dot m. The dynamic behavior of the magnetically coupled piezoelectric bimorph cantilever was also investigated according to the output voltage signal pattern in relation to the deflection dependent on the wind speed. As the wind speed was increased from 2.5 m/s to 6.5 m/s, the deflection and output power of the single piezoelectric bimorph cantilever tended to increase linearly. The highest output power of 24.95 mW, which corresponds to 2.10 mW/cm(3), was obtained at a wind speed of 6.5 m/s for the parallel-connected piezoelectric bimorph cantilever array, implying better performance compared to those reported previously.