Modeling And Experimental Study On Piezoelectric Energy Harvesting With Magnetic Nonlinear Coupling Vibration

At present,the new wireless sensor network has been widely used in military and civilian industry,environmental monitoring,clinical medicine and intelligent agricultural industry.The traditional chemical battery is easy to cause environmental pollution because of its small storage capacity and need to be replaced regularly,especially in some extreme environments where the staff can not arrive at will.In order to maintain the long-term reliability of these devices,researchers turn to piezoelectric generators to convert other easily available clean energy into electricity.Because of its own advantages,environmental energy harvesting has great potential in realizing self-powered operation of wireless sensor networks,so it has attracted great attention of the academic community.In this paper,aiming at the problems of narrow frequency band and low output of linear piezoelectric vibration energy harvester.based on the study of the power generation characteristics of single I-type and L-type piezoelectric energy harvester,a new energy harvester system of I-L composite piezoelectric beam is proposed.According to the energy method,Euler Bernoulli beam theory,Lagrange equation and material mechanics knowledge,the dynamic analysis of the piezoelectric energy harvester of the I-type,L-type and I-L composite beam structure and the vibration modal analysis of the piezoelectric vibrator are carried out,and the electromechanical coupling mathematical model of the I-type,L-type and I-L composite energy harvester system is established.The model is solved by MATLAB.The dynamic characteristics and power generation performance of I-type,L-type and I-L composite piezoelectric energy harvesters are analyzed from many aspects by changing the external excitation frequency,load resistance and structural parameters of the energy harvester system,which provides a theoretical basis for improving the output performance of nonlinear composite piezoelectric energy harvesters.Especially in the I-L combined piezoelectric energy harvester,different nonlinear magnetic coupling effects are obtained by adjusting the horizontal distance between two permanent magnets.The experimental results show that:when the external excitation frequency changes,there is always an optimal resistance value to make the output power of the piezoelectric energy harvester system reach the maximum value.Compared with the non-magnetic piezoelectric energy harvester system,the resonant frequency of the magnetically coupled I-L composite piezoelectric beam energy harvester has a significant shift: the I-shaped piezoelectric beam is shifted to the left,and the L-shaped piezoelectric beam is shifted to the right,which broadens the frequency band of the piezoelectric energy harvester.When the excitation acceleration is 0.2g,the horizontal distance is 20 mm and the excitation frequency is 18.4 Hz,the maximum output power of the PEH is1.2 m W.