| With the development of wireless sensor networks(WSN),wireless sensor nodes are widely used in the monitoring of important facilities such as buildings and bridges,and sensor electronics are used in remote or inconvenient areas.This requires higher reliability and longer service life.But traditional batteries cannot meet these requirements.Therefore,it is necessary to study a kind of battery with zero maintenance and sustainability.There are several kinds of inexhaustible energy in the environment.How to use the energies in the environment and convert them into continuous electric energy is a difficult point that needs to be broken.An energy harvester is the device that converts energy in the environment into a steady stream of electricity.The energy harvester collects energy such as light energy,vibration energy,heat energy,and wind energy in the environment,and the captured energy is converted into electricity by physical or chemical means.Because of its advantages of zero maintenance and miniaturization,energy harvesters have great application prospects in wireless sensor network,environmental monitoring,monitoring,civil infrastructure and industrial control.A levitated airflow energy harvester based on diamagnetic levitation technology is studied in this paper.The levitated airflow energy harvester is mainly composed of a lifting magnet,an upper pyrolytic graphite plate,a levitated rotor,a pinhole nozzle and a lower pyrolytic graphite plate.The diamagnetic levitation technology is used to make the levitation rotor levitated stably between the upper pyrolytic graphite plate and the lower pyrolytic graphite plate,so as to reduce the energy loss caused by the contact between moving parts.The levitated airflow energy harvester studied in this project has the advantages of low starting conditions,high stability and high energy conversion.Firstly,the working principle of the levitated airflow energy harvester is explained and analyzed in detail by combining its structural model.The theoretical analysis of the mechanical and response characteristics of the levitated airflow energy harvester is performed.The magnetic and diamagnetic forces of the levitated rotor are analyzed theoretically.The stable levitation characteristic is studied.The levitated rotor is driven by the airflow to rotate and generate electricity.Furthermore,the driving force of the levitated rotor and the air friction force in the rotating process are analyzed and deduced theoretically.Secondly,the overall magnetic field of the levitated airflow energy harvester is simulated and analyzed by the simulation software COMSOL and MATLAB.The magnetic force and the diamagnetic force received by the rotor are calculated,and the resultant force is analyzed to study the levitation characteristics of the rotor.Further,using the simulation software COMSOL to simulate and analyze the overall flow field of the levitated airflow energy harvester,an airflow driving force of the levitated rotor can be obtained.Then,the simulation software MAXWELL is used to simulate and analyze the output voltage of the levitated airflow energy harvester.Finally,an experimental scheme was developed and an experimental platform was set up.The experimental data of the motion characteristic and output characteristic of the levitated airflow energy harvester were measured experimentally under a series of air flow rates.The experimental results verify the correctness of the theoretical and simulation analysis.An improved diamagnetic-airflow hybrid levitation structure was found in the experiment,compared with the single air or diamagnetic levitation method,it has higher output characteristics and levitation space advantages.Experiments show that the levitated airflow energy harvester based on diamagnetic levitation technology has higher output power and lower starting conditions,and is expected to be applied to sensors after rectification. |
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