Study On Wind Energy Harvesters For Self-Powered Wireless Monitoring Network

With the development of MEMS and low-powered embedded technologies,wireless monitoring networks are increasingly applied in environmental monitoring,disaster prevention,military surveillance and many other fields.However,how to continuously supply energy to many monitoring nodes in the field has become a key issue restricting the development of wireless monitoring networks.The widespread wind energy in the wild environment is a renewable energy with great potential.Converting wind energy into electricity to power wireless monitoring nodes is an effective solution.For the self-powered wireless monitoring nodes from wind energy in the field errvironment,the efficient vertical-axis drag-type electromagnetic wind energy harvesters are designed in this paper.Both of the wind energy harvesters are equipped with vertical-axis drag-type turbines.By optimizing the design of the airflow channel structure and turbine blade parameters,the output power and wind energy conversion efficiency are improved.In addition,by moving the rotor magnets down to the bottom of the turbine and transferring the stator coils to the base,the adaptive directional wind energy harvester reduces the starting torque of the turbine and the moment of inertia of the wind chamber,so that it can harvest the wind energy in any direction with the help of the rudder.At the same time,the switch control circuit and low-powered wireless monitoring nodes are designed in this paper.The self-powered wireless monitoring network with star topology is also built in this paper,and the environmental status values of each monitoring area will be displayed on the computer display interface.The main research contents of this paper are as follows:(1)In order to adapt to the distribution characteristics of wind energy in the natural environment,a fixed directional and an adaptive directional wind energy harvesters are designed in this paper.For the fixed directional wind energy harvester,the finite element simulation and experimental test are compared with each other to optimize the wind tunnel structure and electromagnetic module parameters.For the adaptive directional wind energy harvester,the parameters of the turbines and the electromagnetic power generation module are optimized by combining the fluid simulation with the experimental tests.The output power and power density of the two harvesters at a wind speed of 15 m/s are 468.4 mW,3.9 mW/cm3 and 183.3 mW,1.73 mW/cm3,respectively.In addition,the demonstration experiment in the laboratory and the verification test of output performance in the outdoor environment are carried out for the adaptive directional wind energy harvester.(2)According to the output characteristics of the two wind energy harvesters,the matched energy storage circuit and the switch control circuit are designed,respectively,and the electric energy converted by the wind energy harvester is stored and intermittently energized for the wireless monitoring nodes.At the same time,the wireless angle monitoring node and the low-powered wireless temperature and humidity node are designed,respectively.The computer display interface is compiled according to the serial data structure.After the experiments,the computer can receive the complete serial data sent by the two wireless monitoring nodes within the line of sight of 50 meters and 120 meters.(3)In this paper,the fixed directional wind energy harvester is designed to power the wireless angle monitoring node and the adaptive directional wind energy harvester is used to power the wireless temperature and humidity monitoring node.They are respectively integrated with the switch control circuits,and two sets of self-powered wireless monitoring networks with star topology are constructed.The experimental tests and analysis are carried out for the two sets of monitoring systems.After testing,the self-powered angle monitoring system can realize the angle monitoring and damage alarm at intervals of 5 minutes at a wind speed of 15 m/s,while the self-powered temperature and humidity monitoring system can achieve interval monitoring of 3-4 minutes at an external wind speed of 10 m/s.