High performance piezoelectric energy harvester with dual-coupling beams and bistable configurations

Abstract

To enhance the broadband performance of the bistable energy harvester under low-level vibrations, this paper proposes a piezoelectric nonlinear energy harvester with dual-coupling beams. The proposed device is composed of a linear energy harvester and a bistable nonlinear energy harvester which are elastically connected by a linear spring. The electromechanical model of the proposed harvester is established while the nonlinear restoring force is measured in the experiment. Numerical simulations and experiments are performed for the proposed harvester with various coupling stiffness springs. Since the additional linear oscillator and the coupling spring not only could give the bistable oscillator disturbance at the beginning or during the vibrations, but also can lower the barrier height, numerical and experimental results both show that the proposed harvester can pass through potential wells easier under lower excitation. Compared with a traditional bistable energy harvester, the excitation level acquired for high-energy interwell oscillation is decreased by 56.4% (from 5.5 m/s2 to 2.4 m/s2). The best energy harvesting performance is achieved in the transition region of monostable-to-bistable when the stiffness of the coupling spring is 40 N/m, and the operating bandwidth is increased by 70%. The generated RMS power and the harvested power are increased by 17% and 29%, respectively (under the same excitation of 5.5 m/s2). In addition, the optimal coupling spring stiffness under different restoring forces (potential well depths) is also analyzed in the simulation.