A magnetic coupled piezoelectric energy harvester for ultra-low frequency vibrations

Harvesting human motion energy to power intelligent wearable devices is a research hotspot in the field of energy harvesting. Due to the characteristics of ultra-low frequency of the vibration generated by human motion, the conventional piezoelectric energy harvester cannot work efficiently. This paper proposes a magnetic coupled piezoelectric energy harvester which is composed of two piezoelectric cantilever beams, two endmost magnets, a center magnet, and a tube. The ultra-low frequency vibration of human motion is sensed by the center magnet in the tube and coupled to the piezoelectric cantilever beams by the repulsive force between the endmost magnet and the center magnet. The mathematical model of the harvester is established, and the influence of various parameters on energy harvesting efficiency is analyzed in detail. Through simulation analysis, the proposed harvester can effectively harvest ultra-low frequency vibration energy of human motion.