Research On Spiral Piezoelectric Energy Harvester

The traditional piezoelectric energy harvesting technology has the problems of single harvesting direction,high resonant frequency,low conversion efficiency,low output voltage and output power.Therefore,aiming at the problems above,this paper proposes a right-angle spiral piezoelectric energy harvester and an arc spiral piezoelectric energy harvester.Numerical calculation,model simulation and test analysis of these two spiral piezoelectric energy harvesters are carried out.Compared with conventional energy harvesters,its conversion efficiency,output voltage and power can be significantly improved.The main research contents of this paper are as follows:(1)It is introduced that the piezoelectric energy harvester is based on the piezoelectric energy harvesting theory,and the piezoelectric equation is used to combine the mechanical,piezoelectric and electrical circuits,which lays the foundation for the subsequent theoretical derivation.Finally,the simulation of the most common cantilever beam energy harvester in the energy harvester is carried out,so as to explain that the resonance frequency of this traditional piezoelectric energy harvester is too high,and it is not suitable for use in the low frequency environment.In addition,the piezoelectric energy harvester has a single harvestion direction,which will cause the output efficiency and conversion efficiency of the harvester to be too low.(2)A right-angle helical piezoelectric energy harvester is designed.This harvester not only reduces the resonant frequency but also saves space.By establishing the theoretical model of the right-angle spiral piezoelectric energy harvester,the vibration mode of the right-angle spiral piezoelectric energy harvester is analyzed.The expressions of output voltage and output power are obtained,and the relationship between output voltage and thickness of cantilever beam and piezoelectric layer is found.Through the vibration displacement analysis and stress simulation of the harvester,it is concluded that the right-angle helical piezoelectric energy harvester cannot perform multi-directional energy harvestion.The output voltage of the right-angle spiral piezoelectric energy harvester with an arc of 2π is measured to be 1.8V,and the output power is5.79μW.The harvester with radian 3 π has an output voltage of 0.38 V and an output power of0.12μW.The harvester with radian 4 π has an output voltage of 1V and an output power of0.42μW.(3)A circular arc helical piezoelectric energy harvester is designed.The arc spiral piezoelectric energy harvester can not only reduce the resonance frequency,but also reduce the use of space,and can also harvest energy in multiple directions.The relationship between the output voltage and the length of the cantilever beam is analyzed and compared with the right-angle spiral piezoelectric energy harvester,and the influence of the radian on the multi-directional energy harvesting is analyzed.Experiments show that when the arc spiral piezoelectric energy harvester is 2π,the output voltage is 3.9V and the output power is 35μW.When the radian is 3 π,the output voltage is2.8V and the output power is 28μW.When the radian is 4 π,the output voltage is 10 V and the output power is 75μW.The experimental results show that the output power of the arc helical piezoelectric energy harvester is much larger than that of the right-angle helical piezoelectric energy harvester,and the resonant frequency of the arc helical harvester is smaller than that of the right-angle helical harvester.(4)Finally,combining the advantages of the right-angle helical piezoelectric energy harvester and the arc helical piezoelectric energy harvester,the two helical piezoelectric energy harvesters are combined together.Through simulation,it is found that when the combined angle is 180 degrees,the output voltage and maximum output power.Through this combined structure,the output power of the helical piezoelectric energy harvester can be increased to the m W level,which greatly improves the conversion efficiency and output of the piezoelectric energy harvester.