A magnetic excitation enhanced energy harvester with combined beam for rotational motion

Rotational energy harvester is considered as one of the most attractive harvesters which can directly convert rotational energy into electric energy to achieve self-power supply of rotational wireless monitoring system. In this paper, a novel combined beam bistable rotational piezoelectric energy harvester is proposed to improve the dynamic and electric characteristics. Based on the extended Hamilton's principle, the electromechanical coupling dynamic model of the system is derived. The form mechanism of the bistable rotational energy harvester is elaborated under the guidance of the system's bifurcation and the gravitation effect of tip magnet is investigated. The influence of the key parameters on the dynamic characteristics and electric performance of the system are performed. The prototype is fabricated and the experiments are carried out at different rotational speeds. Nu-merical results are in good agreement with the experimental results, which verifies the effectiveness of the developed model. Numerical and experimental results demonstrate that the proposed harvester has more excellent characteristics in a wide speed range of 300-550 rpm, and the maximum root-mean-square voltage is 9.44 V at 540 rpm, and the corresponding maximum improvement percentage of the RMS voltage is 13.8 %. This study provides a new fundamental theoretical for improving the comprehensive performance of the rotational energy harvesting system.