Research On Theory And Experiment Of Magnetic-assisted Piezoelectric Energy Harvester Actuated By The Compressed Air

With the development of industrial automation,more and more low-power sensors used in the pneumatic industrial production line.As the same time,there exists a lot of clear compressed-air energy in the pneumatic industrial production line.To address the problem of sensors power supply,the researchers propose that utilizing the piezoelectric material to convert the compressed-air energy into electric energy,which can be used to power the low-power sensor.Coupling magnetic force with the cantilever beam piezoelectric energy harvesters can improve the bandwidth and efficiency of the piezoelectric energy harvesters.However,there is little investigate about improving the efficiency of the piezoelectric circular diaphragm,which is used to harvest the compressed air pressure,by coupling the magnetic force with it.Therefore,the theory and experiment research on magnetic-assisted piezoelectric energy harvester impacted by the air pressure was carried in this paper.This paper established a theoretical model of the compressed air load,then analyzed the variation of the compressed air in the sealed chamber and the characteristics of the pressure distribution.The generation mechanism of the piezoelectric circular diaphragm stimulated by the compressed air is researched,then studied the characteristics of the stress and polarization charge distribution of the piezoelectric circular diaphragm.The energy conversion model is also established,and the effect of the magnetic effect on the piezoelectric circular diaphragm is researched.The characteristics of the pressure distribution in the sealed chamber are simulated by the Fluent a fluid simulation analysis software,the simulation provided a basement for structure design of the magnetic-assisted piezoelectric energy harvester.The characteristics of the stress and polarization charge distribution of the piezoelectric circular diaphragm are also simulated by the COMSOL Multiphysics.Moreover,it is investigated that the effects of the magnetic force and direction on the displacement and output voltage of the piezoelectric circular diaphragm in the compressed air.The structure of the magnetic-assisted piezoelectric energy harvester is designed on the research basement of theory and simulation,and the structure size of the magnetic-assisted piezoelectric energy harvester is determined according to the knowledge of mechanical design and mechanical principles.Considering the actual working environment,two types of magnetic-assisted piezoelectric energy harvesters are fabricated.One is the magnetic-assisted piezoelectric energy harvester stimulated by compressed air,and the other is the magnetic-assisted piezoelectric energy harvester stimulated by the alternating compressed air.The experimental testing system was established.The preliminary tests were carried out which investigated the effects of the magnetic force on the output power of the harvester.The relationship between the magnetic force and the distance of the two magnets was experimental researched,which is shown well agreement with the simulation results.It is systemically researched that the output characteristic of the magnetic-assisted piezoelectric energy harvester triggered by the compressed air and magnetic force.The research results indicate that the cancellation of charges on the same surface of the piezoelectric circular diaphragm is inhibited by adjusting the magnitude and direction of the magnetic force,so the efficiency of the harvester is promoted.When the magnetic force is only 0.6% of the air load,the maximum peak powers of the generators are promoted 13.5% and 12.6%,respectively.The experiment results show that the magnetic assisting technique is an effective method to improve the efficiency and generated power in this type of piezoelectric generator.The research results provide a further theoretical and experimental basis for the pneumatic system self-power sensing technology.