A multidirectional broadband pendulum piezoelectric vibration energy harvester utilizing magnetic potential well

Harvesting energy from environmental vibrations using piezoelectric mechanism had attracted much attention for powering wireless sensors over the past decades. To enhance the environmental adaptability of energy harvesters, a multidirectional broadband pendulum piezoelectric vibration energy harvester utilizing magnetic potential well (MPW-PVEH) is proposed in this paper. The MPW-PVEH consists of piezoelectric cantilever beams and a multi-directional pendulum which can oscillate in any direction and pluck the piezoelectric cantilever beam to only yield unidirectional compressive stress. Theoretical analyses and experimental tests were carried out to verify the feasibility of the harvester. The results showed that MPW-PVEH was capable of harvesting horizontal omnidirectional vibration energy between 7 Hz and 10.5 Hz by adjusting the proof mass and torsion radius. Moreover, the operating band of the harvester could be broadened from 4 Hz to 14 Hz by adjusting the magnet distance. The maximum power fluctuation of MPW-PVEH was only 12 % at any horizontal excitation angle, which indicated that MPW-PVEH had good multidirectional consistency. Additionally, the optimum output power of MPW-PVEH could reach 15.6 mW with the load resistance of 90 kΩ at 8 Hz. Furthermore, MPW-PVEH could light 250 LEDs as well as power a temperature sensor and a transmitter module continuously.