Parameter Identification And Response Characteristics Analysis Of Piezoelectric Energy Harvester Based On Composed Beam

With the rapid development of wireless sensor network technology,wireless sensors have been used more and more widely in the condition monitoring of underground mining equipment in coal mines.However,traditional wireless sensors are mostly powered by batteries,and repeated battery replacement will cause a huge workload for later maintenance of the sensors,and the power supply problem needs to be solved urgently.Vibration of large-scale mechanical equipment in coal mines is widespread,and the use of vibration energy harvesting technology is expected to solve the problem of online monitoring and power supply of underground equipment in coal mines.In view of the low frequency,wide frequency band,and multi-directional characteristics of the vibration source in the underground mining part of the coal mine,the research team proposed a piezoelectric energy harvesting based on composed beam(PEH-C).Due to the introduction of structural nonlinearity and magnetic field nonlinearity to broaden the system’s large response bandwidth,the establishment of system dynamics models becomes more complicated.Therefore,it is necessary to establish an accurate dynamic model to reveal the amplitude-frequency response law of the PEH-C under force-electricity-magnetic multi-field coupling,and to optimize the structure parameters of the energy trap to improve its energy trapping performance.This is of great significance to the industrial application of the PEH-C.Aiming at the PEH-C in the article,the paper first uses finite element analysis to verify its multi-directional sensitivity.Subsequently,the magnetizing current method is used to model the nonlinear magnetic force of the system,and the corresponding magnetic force model is obtained.The experimental test data and the simulation results are compared and analyzed,and the magnetic field potential energy characteristics of the system are explored.Finally,combined with Euler-Bernoulli beam theory,piezoelectric constitutive equation,Rayleigh-Ritz method,and based on the Lagrange equation,a dynamic model of the energy trap system is established.In view of the deviation between the model parameters of the system dynamics equation and the actual parameters,the paper uses the voltage output response characteristics of the PEH-C under short-circuit and open-circuit conditions,the mechanical parameters and the identification of electrical parameters was carried out based on the logarithmic decay method and the ridge theory.The analytic expressions of mechanical parameters such as system damping and stiffness,as well as electrical parameters such as electromechanical coupling coefficient and equivalent capacitance coefficient,were obtained,and the accuracy of the model was verified numerically by Runge-Kutta method.Aiming at the problem that the experimental data signal is mixed with external interference signals in the process of energy trap parameter identification,the experimental data is processed through VMD data filtering to filter out the external interference signal,and the actual mechanical parameters and electrical parameter values of the energy trap are identified.Aiming at the problem of solving the dynamic equation of the PEH-C,the paper uses the harmonic balance method to analyze the system response characteristics,discussing the system amplitude-frequency response and power output characteristics of different magnet spacing,excitation amplitude,excitation frequency,load impedance and other parameters.The research results show that the system amplitude-frequency characteristic curve has hard characteristics,and there are multiple solutions and jumping phenomena;the magnet spacing and excitation size are the key factors that affect whether the system can cross the barrier and enter the large-scale inter-well motion;adjusting the magnet spacing,increasing the excitation amplitude method can make the system obtain a higher response output;the magnet spacing,excitation frequency,and excitation amplitude all affect the system output power,and the optimal impedance of the system is mainly determined by the external excitation frequency.Finally,an experimental test platform for the PEH-C is built to verify the voltage output and power output response characteristics of the energy capture device under different external conditions such as magnet spacing,excitation amplitude,excitation frequency,and load impedance under simple harmonic excitation.The experimental results verify the correctness of the theoretical analysis results in this paper,and lay the foundation for the structural optimization design and industrial application of the combined beam piezoelectric energy harvester.