Parametric design for a piezoelectric cantilever carrying oscillators to harvest multi-frequency vibration energy

Abstract

Vibration-based piezoelectric energy harvesters usually work at their resonant frequencies. The resonant frequencies can match, at most, one or two ambient exciting frequencies. In order to freely design multiple operating frequencies to match the given exciting frequencies, several oscillators were attached on a piezoelectric cantilever in this paper, which is named as a multi-mode piezoelectric energy harvester (MPEHer). A distributed-parameter model of the MPEHer was established to predict its output power, and then a lumped-parameter model was derived to determine its operating frequencies. With the lumped-parameter model, the oscillator parameters can be searched for given exciting frequencies. Considering the volume and weight limitation in engineering application, optimizing procedures for the MPEHer were further proposed. Following these procedures, an MPEHer limitedby the oscillator-to-cantilever mass ratio of 2.7 was designed for two given exciting frequencies. Experiments show that, under the same input excitation, the average output power of the designed MPEHer is increased by 82% compared with that of a classical configuration, i.e. a piezoelectric cantilever with a tip mass.