A Novel Magnetic-Coupling Non-Contact Piezoelectric Wind Energy Harvester With a Compound-Embedded Structure

Herein, we propose a magnetic-coupling non-contact piezoelectric wind energy harvester with a compound-embedded structure to improve the power generation performance, environmental adaptability, and reliability. It is mainly composed of a cylinder, a fixed square plate, and a generator which is embedded inside a square shell and indirectly excited by the magnetic force. Unlike most existing harvesters where the performance improvement was achieved by changing cylinder geometry, this harvester realized the enhancement and suppression of the power generation performance via the interference effect of the square plate on the cylinder. The feasibility of the structure and principle of the harvester was proved through simulations and experiments. At the distance-diameter ratio of 2 and the width-diameter ratio of 3, the corresponding Strouhal number of the cylinder varied from 0.223 to 0.113, realizing the conversion from vortex-induced vibration to galloping vibration with larger amplitude. Thus, the maximum voltage of the proposed harvester increased from 7.5 V to 14.8 V, and the corresponding excitation wind speed was reduced by 10.5 m/s. Besides, according to two evaluation indicators proposed in this paper, the performance improvements on the proposed harvester could be characterized as 201.57% and 97.33%, respectively. As a result, the proposed harvester could output a maximum power density of 2.139 mW/cm(3), which was 289.62 % higher than the 0.549 mW/cm(3)of the harvester with a single cylinder.