Performance enhancement of a rotational energy harvester utilizing wind-induced vibration of an inclined stay cable

Abstract

In this paper, an innovative strategy for improving the performance of a recently developed rotational energy harvester is proposed. Its performance can be considerably enhanced by replacing the electromagnetic induction part, consisting of moving permanent magnets and a fixed solenoid coil, with a moving mass and a rotational generator (i.e., an electric motor). The proposed system is easily tuned to the natural frequency of a target structure using the position change of a proof mass. Owing to the high efficiency of the rotational generator, the device can more effectively harness electrical energy from the wind-induced vibration of a stay cable. Also, this new configuration makes the device more compact and geometrically tunable. In order to validate the effectiveness of the new configuration, a series of laboratory and field tests are carried out with the prototype of the proposed device, which is designed and fabricated based on the dynamic characteristics of the vibration of a stay cable installed in an in-service cable-stayed bridge. From the field test, it is observed that the normalized output power of the proposed system is 35.67 mW (m s(-2))(-2), while that of the original device is just 5.47 mW (m s(-2))(-2). These results show that the proposed device generates much more electrical energy than the original device. Moreover, it is verified that the proposed device can generate sufficient electricity to power a wireless sensor node placed on a cable under gentle-moderate wind conditions.