A novel elastic strip suspension-based bi-directional electromagnetic wind energy harvester designed specifically for wind energy factories

Abstract

In this study, we propose a novel parallel elastic strips suspended electromagnetic wind energy harvester (ESWEH) based on wind-induced vibration. Profiting galloping phenomena caused by wind flow, the hollow square tube is conceived to generate a significant transverse vibration, and two magnets are equipped on the hollow square tube to generate electrical energy utilizing the electromagnetic induction principle. The symmetrical design of the ESWEH enables it to harvest bi-directional wind energy, while this structure is easy to be assembled into an integrated energy harvesting factory to meet various power supply requirement. A theoretical model is developed to explain the operational mechanism of the proposed electromechanical coupling system. Further, a series of experiments are conducted in a wind tunnel to examine its power generation characteristics (including power-resistance, voltage-resistance) under a closed-circuit condition. The results of the experiments indicate that, when the wind velocity exceeds 2 m/s, the ESWEH equipped with both front and back attached fins produces a continuous and stable current output, with a voltage value exceeding 2.0 V and power exceeding 2.0 mW. Moreover, at an incoming wind velocity of 4 m/s, anaverage power of 7.8 mW is obtained, accompanied by a Root Mean Square (RMS) voltage of 3.2 V when connected to a resistance of 1.2 kΩ. In conclusion, the proposed ESWEH shows good performances in various aspects such as a simplified structure, efficiency-cost, low critical wind velocity and a high-power capacity. The experimental results further indicate that the proposed structure has potential application in construction of a stable power supplying system and wind energy factory for wireless sensors.