Research on a rotary piezoelectric energy harvester based on movable magnets

A hybrid energy harvester (HEH) is designed using a movable magnet to harvest the mechanical energy for rotational motion. One movement of the movable magnet can generate electricity from piezoelectric nanogenerators (PENG) and electromagnetic generators (EMG), improving the energy conversion efficiency of HEH. The main factors affecting the motion characteristics of active magnets (number of magnets and magnet diameter) are illustrated through theoretical modeling and simulation, and the voltage characteristics of EMG and vibration characteristics of PENG are analyzed. According to the main factors affecting the motion characteristics, the experimental testing system was set up. The results show that the voltage of PENG and EMG can be up to 6.55 V and 1.37 V, respectively as the magnet diameter is 10 mm and the number of magnets is 5. The maximum power of PENG is 2.4 mW at 30 kΩ, and the power of EMG is 0.49 mW at 4 kΩ. The application experiment also proves the feasibility of the practical application of R-PEH, which provides a new solution for the research of hybrid energy harvesting systems.