Applied Energy, Vol.239, 735-746, 2019
A water-proof magnetically coupled piezoelectric-electromagnetic hybrid wind energy harvester
Small-scale wind energy harvesting can be a potential way to yield endless electrical energy for small and micro mechanical systems, which has gained extensive interest from both the academia and industry. The environmental adaptability and reliability of the harvester are key issues that cannot be ignored in practical applications. To overcome these challenges, we propose a novel water-proof hybrid wind energy harvester (WP-HWH) using magnetic coupling and force amplification mechanisms. Using a symmetrical opposite magnetic arrangement, the resistance torque is reduced as much as possible and the effective magnetic force is enhanced, which is beneficial to harvest energy at low wind speeds. The magnetic force can be further amplified and applied to the piezoelectric layer more evenly, thereby achieving higher power density and better reliability. The key components of the energy harvester can be packaged easily owing to the non-contact magnetic coupling mechanism. Thus, it can operate effectively in a harsh environment, such as rainfall. A theoretical model is developed to characterize the WP-HWH. Both simulations and experiments are performed to validate the design and analysis of the WP-HWH. The experimental results indicate that combining the advantages of piezoelectric energy harvester and electromagnetic energy harvester, the WP-HWH has enhanced flexibility for practical applications as well as an outpower. Additionally, under rainfall, the WP-HWH can operate continuously for more than 100,000 cycles and saturates at 3157.7 mu W at a wind speed of 7.0 m/s, implying good mechanical durability.