Research On Piezoelectric Energy Collector Based On Coupled Oscillator Model

Piezoelectric energy collector can replace the battery and provide energy for most kinds of micro devices.And due to its advantages of considerable output power and high output voltage,it has bright prospects.This paper intends to collect the vibration energy of the vehicle with the frequency band from 5 Hz to 25 Hz.However,the traditional cantilever beam piezoelectric energy collector has a narrow operating frequency band,which makes it difficult to cope with random changes in external excitation.In response to this problem,this paper proposed a novel structure of piezoelectric energy collector with a wide frequency band.The performance of the energy collector was analyzed by theoretical analysis,finite element simulation and experimental research.The main work of the full text is summarized as follows:Firstly,this paper analyzed the traditional single-cantilever-beam piezoelectric energy collector by mechanical vibration theory.On this basis,two single-cantilever-beam piezoelectric energy collectors are connected by soft spring to form the coupled oscillator.Each single-cantilever-beam piezoelectric energy collector can be regarded as a oscillator.The analysis of the coupled oscillator showed that each oscillator in the coupled oscillator model has a wider operating frequency band.Based on the coupled oscillator model,a piezoelectric energy collector structure consisting of two oscillators(Oscillator 1 and Oscillator 2)was designed,and the selection of materials and the geometric parameters of each component were determined according to the work requirements.Secondly,the finite element analysis of the designed piezoelectric energy collector was carried out by running ANSYS simulation software,including static structural analysis,modal analysis,transient response analysis and harmonic response analysis.Static structural analysis calculated the strain and stress of the energy collector under stationary state.Modal analysis studied the natural frequencies and corresponding modes of each oscillator of the piezoelectric energy collector.Transient response analysis compared the output performance of the designed energy collector under different external excitations.Harmonic response analysis obtained the frequency response of the energy collector's output performance.Based on this,the variation of the operating frequency band of the energy collector under coupling was further discussed,which provided guidance for the subsequent experimental analysis.Finally,an experimental prototype of the piezoelectric energy collector based on coupled oscillator model was fabricated and related experiments are carried out.Under the sinusoidal external excitation of a frequency range from 5 Hz to 25 Hz and an acceleration of 3 m/s~2,Oscillator 1 and Oscillator 2 could respectively generate a maximum open circuit output voltage of 2.2 V while operating independently.And when they are coupled,Oscillator 1could generate a 2.4 V maximum open output voltage and Oscillator 2 could generate a 2.2V maximum open output voltage.By analyzing the experimental results,the natural frequency of Oscillator 1 is about 17.1 Hz,and the natural frequency of Oscillator 2 is about21.1 Hz,which satisfies the need to collect vibration energy of 5 Hz to 25 Hz.In addition,by comparing the frequency response curves of the open circuit output voltage of the energy collectors working independently and under coupling,the results show that the operating frequency band of the energy collector was broadened under coupling.