Analysis Of The Electromechanical Coupling Characteristics Of Piezoelectric Energy Harvester Based On Wind Energy Harvesting

Wind energy is a common form of natural resources,because of its large reserves,wide distribution and renewable,so it is also one of the key development and utilization of clean energy sources.At present,the most common engineering technical condition for wind energy utilization is to use large turbine blades to convert wind energy into electrical energy,so as to provide convenience for people's production and life.In recent years,with the rapid development of wireless network sensing technology,wireless electronic equipment and micro-electronic products,how to convert wind energy into electric energy to provide continuous electrical energy for micro-electromechanical systems has become a research hotspot.Because of piezoelectric effect,piezoelectric materials can convert mechanical energy into electrical energy when structures vibrate,so the piezoelectric energy harvesters have been widely studied and applied in this field.At present,most literatures have studied the wind energy harvesting and conversion characteristics of rectangular piezoelectric cantilever beam under the hypothesis of small deformation theory.However,in practical environment,when the external wind speed is large,the cantilever beam structure is prone to large deformation.Moreover,considering the non-linearlity of wind load parameters and other factors,the nonlinear vibration of the cantilever beam will also be induced.Therefore,this paper extends the research object from the traditional rectangular cantilever beam to the variable cross-section cantilever beam,and carries out a series of theoretical calculation and research on the nonlinear vibration characteristics and energy capture characteristics of the energy harvester under wind excitation.Based on the large deformation theory,the nonlinear partial differential governing equations of piezoelectric cantilever beam harvester are derived by using the Hamiltonian principle in this paper.Then the dynamic equations of electromechanical coupling are discretized by Galerkin method,and the reduced order model of the nonlinear ordinary differential governing equations is obtained.Subsequently,the theoretical model is numerically calculated,and the effects of wind speed,load resistance,width ratio,square cylinder mass and geometry on the vibration characteristics and power output response of the piezoelectric energy harvester are analyzed.The results show that the electrical response of the system is the result of the interaction of different factors,in order to maximize the capture of wind energy and improve the power output,the influence of different factors should be fully balanced so as to make the most reasonable choice and design under specific conditions.In order to further study the response characteristics of piezoelectric cantilever energy harvester,a magnet and a coil are added to the trapezoidal piezoelectric cantilever to form a piezoelectric-electromagnetic hybrid energy harvester.By studying the influence of magnet position,load resistance of hybrid circuits and wind speed on the vibration and energy harvesting characteristics of hybrid system,it can be found that although the hybrid energy harvesting device can restrain the power output of piezoelectric circuit to a certain extent,it also reduces the displacement amplitude of the vibration system,so it can reduce the risk of structural cracking damage.In addition,the overall output power of the hybrid energy harvester can be maximized by adjusting the position of the magnet,the load resistances of the piezoelectric circuit and the electromagnetic circuit under certain external wind speed.The results of this paper can provide some references and suggestions for the application of piezoelectric energy harvesting devices in practical engineering and further design optimization.