Analysis of broadband characteristics of two degree of freedom bistable piezoelectric energy harvester

Abstract

In order to broaden the working frequency band of the piezoelectric energy harvester and improve the energy harvesting efficiency, a new two degree of freedom bistable piezoelectric vibration energy harvester is designed in this paper. It consists of a basic cantilever beam, a mass, a piezoelectric cantilever beam and magnets. The equivalent model of the system is established using lumped parameter method, and the two degree of freedom bistable motion equation is established considering the influence of electromechanical coupling. Using Matlab, the motion equation is calculated, and the curve of the system voltage with time and frequency is obtained. The voltage output characteristics of the system under bistable vibration and the influence of the stiffness and the mass of the basic cantilever beam on the output performance of the system are analyzed. Under the excitation of 0.3 g simple harmonics, the two degree of freedom bistable piezoelectric energy harvester is experimented using one-way frequency-increasing sweep. The results show that the maximum output voltage of the two resonance band of the energy harvester is 26 V and 13 V. Compared with the single degree of freedom bistable structure, the frequency band is widened by 10 Hz. In addition, reducing the stiffness of the basic cantilever beam and increasing the mass of mass block are all beneficial to broadening the working band of the harvester.