Mechanistic And Experimental Study Of A Piezoelectric-electromagnetic Composite Energy Harvester For Rotating Environments

With the accelerated industrialization,the demand for energy is increasing,and the energy supply mainly comes from fossil fuels,which also brings serious air pollution problems.The development of renewable energy sources,such as mechanical energy,solar energy,wind energy,etc.,has become particularly important.In addition to this,portable devices and wireless sensor networks have also developed very rapidly in recent years.Currently,most of the sensors and portable devices are still powered by dry batteries.Dry cell batteries can cause environmental pollution and self-discharge problems,so many researchers are working to develop renewable energy technologies that can replace dry cell batteries,such as piezoelectric power generation technology,electromagnetic induction technology,triboelectric technology,etc.The use of renewable energy technologies to harvest and convert clean energy from the environment into electrical energy has been a hot topic of research in recent years.In this paper,the piezoelectric-electromagnetic combination is used to effectively collect the rotating energy in the environment,and the structural design and parameters of the harvester are studied to maximize the output power and improve the harvesting capability of the prototype,which largely solves the problem of limited output power of a single harvesting mechanism.Firstly,we summarize the current status of domestic and international research on piezoelectricity,electromagnetism and piezoelectricity-electromagnetism composite,understand the research dynamics of the current directions,and provide ideas for the structural design of piezoelectricity-electromagnetism composite energy harvester for rotating environment.Two types of piezoelectric-electromagnetic energy capturers oriented to the rotating environment are designed for the idea of harvesting in the rotating environment,and the hybrid piezoelectric-electromagnetic energy harvester with cam-increased frequency type and the hybrid piezoelectric-electromagnetic energy harvester with magnetically coupled suction-repulsion structure are proposed.The dimensional parameters between the components are determined according to the fit and the movement between each structure.In addition to this,this paper also presents the parameter variables that affect the strong correlation of the output performance of the prototype,and provides a preliminary theoretical verification of them through theoretical and simulation analysis,laying the foundation for the subsequent experimental development.Based on the two designed piezoelectric-electromagnetic energy harvesters for rotating environment,an experimental platform was built to investigate the output voltage and power generated by different parameter variables,and the application performance of the cam-frequency incremental hybrid piezoelectric-electromagnetic harvester and the magnetically coupled suction-repulsion hybrid piezoelectric-electromagnetic harvester were demonstrated respectively.In the case of the hybrid piezoelectric-electromagnetic harvester of the cam frequency increment type,the voltage generated by the piezoelectric and electromagnetic generating units is 53.74 V and 3.16 V,respectively,at a speed of 500r/min when the number of cam projections is 3 and the length of the magnet mounted at the end of the piezoelectric cantilever beam is 10 mm.With an external impedance of 10 KΩ,the hybrid piezoelectric-electromagnetic generation unit can generate 1.49 m W of output power,which can successfully power scientific computers and light-emitting diodes.For the hybrid piezoelectric-electromagnetic capturer with magnetically coupled suction-repulsion structure,the voltages generated by the piezoelectric and electromagnetic generation units are 42.87 V and 2.94 V,respectively,when the magnet mass at the end of the piezoelectric cantilever beam is 3.2 g and the mounting angle of the piezoelectric cantilever beam is 60° and the rotational speed is 300 r/min.With a maximum output power of 13.32 m W,it can successfully power low-power electronic devices such as light-emitting diodes,providing a practical application and meaningful solution for rotational energy harvesting.