Theoretical Modeling And Experimental Study Of Nonlinear Electromagnetic Energy Harvester Based On Double-clamped Beam

In recent years,with the rapid development of wireless sensor networks and their wide application in the areas of environmental monitoring,smart city,internet of things,national security and so on,the problem of power supply has become the bottleneck restricting their further development.The environmental kinetic energy harvester is an effective way to solve the problem of the power supply of wireless sensor network nodes.Aiming at the shortcomings of narrow working frequency band and poor environmental adaptability of the environmental kinetic energy harvester,this paper carried out the corresponding theoretical and experimental research,which has important scientific significance and application value.Aiming at the key problem that the frequency bandwidth of linear vibration energy harvester cannot meet the practical application demands,the paper proposed a structure of nonlinear electromagnetic vibration energy harvester based on double-clamped beam.To solve the problem that the difference of dynamic deformation and static deformation is neglected in the lumped parameter model,a distributed parameter model had been established.It is proved that the geometric nonlinearity of double-clamped beam is a cubic nonlinearity,it is also found that the strong nonlinearity can broaden the frequency bandwidth of the electromagnetic vibration energy harvester without affecting its maximum voltage.Moreover,a asymmetric structure had been proposed,the experimental results show that the structure can improve the maximum open-circuit voltage and the maximum average power of the nonlinear electromagnetic energy harvester by 52%and 133%respectively.Based on the distributed parameter model,a theoretical exploration was carried out for a nonlinear electromagnetic wind-induced vibration energy harvester based on double-clamped beam.A flutter dynamical equation with full modes participation was established combined with the Theodorsen’s plate aerodynamics.It is found that the flutter of the nonlinear electromagnetic wind-induced vibration energy harvester based on double-clamped beam is a bending-torsional coupled flutter and the flutter critical wind speed was calculated.Furthermore,the structural optimum design was completed,a prototype was fabricated and a test platform was built,the output performance test of the prototype was completed.The experimental results show that the maximum open-circuit voltage and average power of the prototype of vibration energy harvester under 1g acceleration were 3.61 V and 1.78m W,the frequency bandwidth was 11 Hz,the flutter critical wind speed of the wind-induced vibration energy harvester was 6.5 m/s,the output power increased with the increase of the wind speed,the prototype of wind-induced vibration energy harvester can output an average power of 971μW at the wind speed of 11.2 m/s.The main contributions of this paper are listed as follows:（1）The research background and current status of this paper were introduced,the key scientific and technical problems of the environmental kinetic energy harvester were analyzed and the research objectives and main contents of this paper were determined.（2）The structure of the nonlinear broadband electromagnetic vibration energy harvester based on double-clamped beam was proposed and the corresponding theoretical research of electromechanical coupling was carried out.The shortcoming of the lumped parameter model was pointed out and a distributed parameter model was established.The main performance indicators of the energy harvester were analyzed and the effects of the nonlinear coefficient,the acceleration and the damping ratio on the resonant frequency,the maximum open-circuit voltage and the frequency bandwidth of the energy harvester were investigated.（3）The structural optimum design of the nonlinear electromagnetic vibration energy harvester based on double-clamped beam was carried out.A protype was fabricated and a vibration test platform was built.The output performance test of the prototype were completed and the distributed parameter model modal had been experimentally verified.Besides,an asymmetric structure was proposed,which can effectively improve the maximum voltage and the maximum average power of the nonlinear electromagnetic vibration energy harvester,however,it reduces the frequency bandwidth.（4）The possible flutter modality of the nonlinear electromagnetic wind-induced vibration energy harvester based on double-clamped beam were analyzed.A flutter dynamical equation with full modes participation was established based on the distributed parameter model and the Theodorsen’s plate aerodynamics.It is found that the flutter of the nonlinear electromagnetic wind-induced vibration energy harvester based on double-clamped beam is a bending-torsional coupled flutter.（5）The structure optimum design of the nonlinear electromagnetic wind-induced vibration energy harvester based on double-clamped beam was carried out based on the flutter dynamic equation.A protype was fabricated and a wind tunnel test platform was built,the output performance test and analysis of the prototype was completed,the result shows that the critical wind speed of the prototype with central magnets dropped by about 32%compared with the prototype when l₁=25 mm.