Research On Piecewise Linear Piezoelectric-Electromagnetic Hybrid Energy Harvester

With the continuous development of integrated circuits,micro-electro-mechanical systems(MEMS)are widely used in wireless sensor networks,medical and health,environmental monitoring,information and communication and other fields.Traditional MEMS products use battery for energy,but the short battery life and the high cost of replacement are restricting the further development of MEMS products.In recent years,scholars have begun to study environmental vibration capture device instead of batteries for MEMS products.The energy conversion forms are mainly piezoelectric,electromagnetic and electrostatic.Compared to electrostaticenergy harvester,piezoelectric and electromagnetic energy harvester efficiency is higher and does not require external power supply,and thus get more attention.However,in the current study of piezoelectric and electromagnetic energy harvester,there are many disadvantages such as narrow working band and low efficiency.Therefore,it is of great theoretical and practical significance to study a kind of wide-band,high-efficiency energy harvester.This paper reviewed the research status of the piezoelectric,the electromagnetic and hybrid piezoelectric-electromagnetic energy harvester,In view of the low efficiency of energy harvesting and the narrow band problems,a piecewise linear piezoelectric-electromagnetic hybrid energy harvester was designed.On this basis,the power performance and movement characteristic of energy harvester can has carried on the theoretical analysis and experimental research.The main work of the paper focuses on the following aspects:Firstly,we design a piecewise linear piezoelectric-electromagnetic hybrid energy harvester,and established energy harvester’s 3 d model.Considering the influence of the piezoelectric force and electromagnetic force on the power generation performance of the system,the mechanical equations of the piezoelectric part and the electromagnetic part are established by using the electromechanical coupling coefficient and the equivalent circuit model.At the same time,based on the spring mass damping model of energy harvester,the mathematical model of piecewise linear piezoelectric-electromagnetic hybrid energy harvester is obtained.Secondly,in view of the mathematical model of piecewise linear hybrid energy harvester,the average method was used to solve the model.The expressions of amplitude,voltage,current and output power are obtained.The influence of parameter variation on output performance is analyzed,and the conclusion can be drawn that the power performance of the captive can be improved by choosing the optimal load,the appropriate acceleration and adjusting the piecewise linear structure.Then,based on the basic theory of stability,the motion differential equation is solved and the stability and unstable regions of the motion are determined.The influence of the bifurcation parameters on the amplitude stability of the motion is analyzed.The results show that the piecewise linear hybrid energy harvester can not occurs bifurcation that used in the experimental process or in the normal environment.Finally,the experimental system of piecewise linear piezoelectric-electromagnetic hybrid energy harvester is established,and the experimental research on its performance is carried out.The experimental tests are carried out from the aspects of the existence of piecewise linear energy harvesting system,single piezoelectric energy harvesting system,single electromagnetic energy harvesting system and hybrid energy harvesting system.The experimental results show that At 0.3g acceleration,the piecewise linear hybrid energy harvester broaden the 8Hz frequency band compared to it without the piecewise linear characteristic.And the output power of the hybrid energy harvester is higher than the single energy harvester.The maximum output power of the composite combiner in the first resonance interval is 7.3 times and 1.45 times higher than that of the single piezoelectric trap and the single electromagneticenergy harvester,The second resonance interval increased by 1.25 times and 11.59 times.The experimental results are in good agreement with the theoretical results,which proves the feasibility of the averaging method to solve the power performance of piecewise linear hybrid energy harvester.In this paper,the piecewise linear piezoelectric-electromagnetic hybrid energy harvester has the characteristics of broadband,high efficiency,for the research of microelectronic system self-energized provides design idea.In addition,the formula based on the averaging method is suitable for the further miniaturization design and optimization of the piecewise linear piezoelectric-electromagnetic hybrid energy harvester.