Affiliations: [a] School of Manufacturing Science and Engineering,
Sichuan University, Chengdu, Sichuan, China | [b] School of Mechanical Engineering, Nanjing University
of Science and Technology, Nanjing, Jiangsu, China
Abstract: This paper presents a novel piezoelectric harvester to convert
ambient vibrations into usable electrical energy. Unlike the normal cantilever
beam structure, the piezoelectric harvester developed in this paper is based on
the wafer-stack configuration, which is appropriated for large force
vibrations. Firstly, two electromechanical models (without and with a rectifier
circuit), considering both the mechanical and electrical factors of the
harvester, were built to characterize the harvested electrical power across the
external load. Exact closed-form expressions of the electromechanical models
have been given to analyze the maximum harvested power and the optimal
resistance. It was shown that the harvested electrical power depends on the
external vibration characteristics, the natural frequency, the mechanical
damping factor, the normalized electrical load, the stiffness of the harvester
and the overall electromechanical coupling coefficient of the harvester.
Finally, a shake table experimental testing was conducted to evaluate the
feasibility of the proposed piezoelectric wafer-stack harvester under standard
sinusoidal loadings. Experimental results show that the harvester can generate
a maximum 16 mW DC electrical power for sinusoidal loading with 3040 N
amplitude and 2 Hz frequency, and the harvested electrical power is
proportional to the strength of the exciting vibration.
Keywords: Energy harvesting, piezoelectric, wafer-stack, electromechanical model
