Design and analysis of a broadband three-beam impact piezoelectric energy harvester for low-frequency rotational motion

Abstract

This paper proposes a three-beam impact energy harvester (TIEH) to enhance the energy harveting efficiency for low-frequency rotational motion. The design includes three beams, including the excitation beam, the harvesting beam and the protection beam. The excitation is generated by the impact of the excitation beam and the harvesting beam, and the harvesting beam breaks through the resonance state limitation to obtain more excellent performance in the low-frequency band. Through the design of centrifugal force, the soften or harden effect can be obtained to adapt to different application scenarios. In this paper, the TIEH electromechanical coupling model is established, and the concept of design factor is proposed for the centrifugal force scheme to simplify the design and analysis. The tested TIEH can obtain 52.1 μW at 4.2 Hz with 1.9 Hz bandwidth over 2 V. The Soften TIEH has a 23.0% power increase and 15.8% bandwidth reduction and the Harden TIEH has a 11.9% power reduction and 52.6% bandwidth increase. The results show that the TIEH has the characteristics of low frequency band, wide frequency band, and parameter insensitivity, and has the potential to be applied to a low-frequency rotational structure with limited volume.