Development of a novel non-contact piezoelectric wind energy harvester excited by vortex-induced vibration

Abstract

Wind energy harvesting using piezoelectric transduction is becoming a promising alternative for battery-free portable and wireless electronics. A novel non-contact vortex-induced vibration-based piezoelectric wind energy harvester using an indirectly excited composite piezoelectric transducer is investigated to enhance the reliability and environmental adaptability in this paper. It is very different from the most existing vortex-induced vibration-based piezoelectric wind energy harvesters where piezoelectric cantilever beams interacted directly with the airflow. Herein, wind energy harvesting from vortex-induced vibration of a composite piezoelectric transducer embedded in a cylindrical shell was explored theoretically and experimentally. Furthermore, a pre-bending vibrator subjected only to unidirectional compressive stress was employed to further enhance the reliability of the piezoelectric transducer. To verify the feasibility of the proposed principle and design, a prototype of the non-contact piezoelectric wind energy harvester was fabricated and tested in terms of vibration characteristics, wind speed bandwidth and output power. The results showed that the wind speed bandwidth, vibration displacement and output voltage were increased with the enhancing transducer mass and the decreasing shell mass as the wind speed increased. There was an optimal load resistance of 300 kΩ to maximize the output power. At the wind speed of 40.0 m·s−1 and transducer mass of 65 g, the maximum power of 1.438 mW was recorded in terms of a single piezoelectric pre-bending beam. Meanwhile, the non-contact piezoelectric wind energy harvester could be effectively operated within a wide wind speed range from 5.5 m·s−1 to 40.0 m·s−1 (namely wind speed bandwidth of 34.5 m·s−1) when an output voltage of 5 V was used as the reference value.