Performance investigation and parameter identification of inverse variable cross-section energy harvester

Abstract

An important issue in traditional energy harvesters is that the best performance of the device is limited to the uneven longitudinal strain and electric displacement distributions. One solution to this challenge is to incorporate of variable cross-section design and rotational motion. In this study, we propose a new rotational inverse complex piezoelectric energy harvester featuring two beams for ultra-low-frequency rotation applications. A comprehensive electromechanical model is developed based on the extended Hamilton's principle, and the analytical models are extracted for vibration response and electric performance under ultra-low-frequency excitations. Closed-form analytical expressions of the rotational frequency, electrical load resistance, and centrifugal coefficient are derived to give in-depth insights into the influence mechanism of the centrifugal softening effect for the extreme conditions of RL→0 and RL→∞. Moreover, we propose a parameter identification method to recognize optimal electrical load resistance for ultra-low-frequency rotational scenarios in the absence case of experimental equipment. Based on the validated theoretical model, parametric studies are conducted to investigate the effects of the structural parameters on the dynamic behaviors and output electric performance, it can be concluded that the appropriation selection of the structural parameters can change the dynamic behaviors of the harvester and enhance the energy harvesting performance. Besides, the prototype of the proposed harvester was designed and fabricated and experiments were carried out. Both analytical simulation and experimental results show that the proposed inverse energy harvester has an excellent harvesting performance at the ultra-low-frequency rotational excitations, and the output voltage of the proposed inverse energy harvester is 12% larger than that of a traditional inverse energy harvester.