A Triple Piezoelectric-Electromagnetic-Piezoelectric Energy Harvester with Cam Contact Driven and Cylindrical Magnet Noncontact Driven

For the traditional energy harvester converting other energy forms into electrical power, lots of energy is wasted as heat or other forms due to the single energy transduction mechanism. To further improve the energy conversion efficiency, the study presented here provides an idea and realization of a triple piezoelectric-electromagnetic-piezoelectric energy harvester with cam contact driven and cylindrical magnet noncontact driven for improving the conversion efficiency of energy. The proposed energy harvester is composed of a rectangular piezoelectric energy harvester (RPEH), a circular piezoelectric energy harvester (CPEH), and an electromagnetic energy harvester (EMEH) for harvesting mechanical energy. The design concepts and working principle are evaluated and explained with the structural and Simulink models. The output performance is experimentally tested under different rotating speeds, cam geometries, lengths of magnets, and load resistances. The results reveal that the output power can achieve a milliwatt level (1.34 mW) with 3 cam protrusions, 15 mm magnet length, and 200 r min⁻¹ rotating speed. Finally, we successfully demonstrate the harvester has great potential in powering low-power electronics such as light-emitting diodes and digital clocks.