A hybrid energy harvester with bistable mechanism based on flapping-wing structure

Abstract

The utilization of low-frequency vibrations distributed in nature to provide energy supply for microelectronic devices has drawn greater attention. Based on the principle of flapping wings of insects, a bionic flapping wing bistable energy harvester (BFBEH) for low-frequency vibration is proposed by using a symmetrical flexible cantilever beam mounted with piezoelectric fibers to simulate the wings of insects, and the lifting and lowering motions of the center unit constructed by a magnetic inductor coil and a levitating magnet to simulate the muscle motions of insects. In consideration of broadening the energy harvesting frequency band, nonlinear magnetic force is introduced to realize bistability. When excited by vibration, the magnetic induction coil and the suspended magnet generate relative motion to realize electromagnetic energy harvesting, while the cantilever beam unit connected to the induction coil frame realizes piezoelectric energy harvesting. In particular, the coupling of a permanent magnet as a mass block at the end of the cantilever beam with a fixed steady state magnet can construct the bistable characteristics of the flapping wing. Theoretical modeling of the bionic energy harvester is established. The focus is on the theoretical modeling of the bistable mechanism and the numerical simulation of its potential energy. The electromagnetic simulation results show that the structure has an effective energy harvesting capability in a low frequency environment. An experimental system is set up to analyze the effects of excitation frequency, limit height, and the number of permanent magnet groups at the end of the flexible cantilever beam on the output performance of the bistable energy harvesting device. The experimental results show that the excitation frequency, limit height, and magnetically coupled bistable mechanism have a large influence on the output power of the collector, and the output power of the BFBEH under low-frequency vibration is greater than 0 .2W.