Design And Performance Research Of Piezoelectric Energy Harvester Based On New Trapezoidal Beam Structure

In recent years,wireless sensor networks have put forward a greater demand for small-scale,portable and renewable energy.Researchers expect to use piezoelectric energy harvesting technology to replace traditional electrochemical cells that are increasingly exposed to more problems to prolong the service life of wireless sensors.In order to further improve the electrical output of piezoelectric energy harvester,this thesis studies the piezoelectric energy harvester based on trapezoidal beam,which has certain scientific value and practical significance.On the basis of summarizing the relevant research on piezoelectric energy harvesting technology in recent years,this thesis puts forward a new type of notched trapezoidal beam structure which can further improve the electrical output characteristics of piezoelectric energy harvester.The theoretical model of lumped parameters based on piezoelectric energy harvester of vibrating trapezoidal beam is established,and six kinds of free end notch schemes with equal area and different shapes are designed,and the vibration characteristics of the above-mentioned new notched trapezoidal beams are obtained through mathematical modeling and analysis.The influence of different notch schemes on the electrical output characteristics of piezoelectric energy harvester is analyzed by COMSOL Multiphysics finite element simulation software.In order to make the piezoelectric energy harvester supply power to the load more conveniently and efficiently,an energy collection interface circuit based on LTC3588-1 power management chip is designed,and its feasibility is verified by an application case of a low-power Internet of Things temperature and humidity sensor system.A prototype of a new type of notched trapezoidal beam piezoelectric energy harvester is developed and its electrical output characteristics are studied through experiments.The experimental results show that the prototype with the best electrical output characteristics has a maximum open circuit voltage of 7.99 V and a maximum output power of 6.76 W under the sinusoidal excitation of 0.5g acceleration and 44 Hz,which is 56.1% and 51.9% higher than that of the traditional trapezoidal beam prototype without notches.The main works of this thesis are as follows:(1)This thesis analyzes the research progress of piezoelectric energy harvesting technology by experts and scholars at home and abroad in recent years,points out the main problems in the existing research,and then determines the innovation,organizational structure and main research contents of this thesis;(2)The mathematical model of a new notched trapezoidal beam is established,and the inertia moment equation and strain equation used to describe its vibration characteristics are derived,and then the expressions of output voltage and output power used to describe the electrical output characteristics of piezoelectric energy harvester are calculated;(3)The finite element simulation model based on COMSOL Multiphysics is constructed,and modal analysis,deflection analysis,output voltage frequency response analysis,acceleration correlation analysis and load correlation analysis are carried out for each model from multiple angles,and the optimal notch scheme is determined by synthesizing the analysis results from various aspects;(4)In order to enable the piezoelectric energy harvester to supply power to the load more conveniently and efficiently,an energy collection interface circuit based on LTC3588-1 power management chip is designed and its feasibility is verified by an application case of a low-power Internet of Things temperature and humidity sensor system;(5)The materials and processing technology used in each part of the principle prototype are determined,and a total of seven principle prototypes(one traditional trapezoidal beam without notch and six new trapezoidal beams with notch)are developed and assembled into piezoelectric energy harvesters.According to the established experimental method,the electrical output characteristics of each principle prototype are tested and analyzed on the experimental platform.