| In order to meet the requirement of real-time power supplies for rotating machinery monitoring system,and solve the problems of low reliability and narrow effective bandwidth of existing piezoelectric generators,a rotary magnet exciting piezoelectric generator with amplitude limiting by moving cam was proposed.A theoretical model for performance evaluation was established based on Fourier series,and the influence of system parameters on its response performance was obtained by simulation and experimentally.The main contents are summarized as follows:1.Based on the theory of piezoelectric and material mechanics,a single cantilever piezoelectric beam and a piezoelectric-cam excitation system were established by using the Comsol software.The statics and dynamics characteristics of the single cantilever piezoelectric beam and the kinematics characteristics of the piezoelectric-cam excitation system were carried out.The influence of the structural parameters of the single cantilever piezoelectric beam on its structural stress,natural frequency and power generation performance,the structural parameters of the cam and excitation parameters(excitation amplitude and frequency)on the deformation of the cantilever piezoelectric beam and the contact pressure between the contacts were obtained.By then,the structural parameters suitable for the piezoelectric generator were determined,which can provide reference for determining reasonable structure parameters of the cantilever piezoelectric beam and cam.2.The working principle of the rotary magnet exciting piezoelectric generator with amplitude limiting was explained,and a finite element model of the magnetic coupling excitation force between the excitation magnets and the excited magnet was established,and the waveform and amplitude of the excitation force are obtained,the key factors that affecting the excitation force waveform and amplitude are magnet number ratio and excitation distance.According to the vibration analysis theory and excitation force,a dynamic model of the generator system was established and simulated analysis was performed.The influence of the magnet number ratio,excitation distance,cam system stiffness,excitation force,cam lift and lift angle on the output performance of piezoelectric generator was studied.3.In order to verify the correctness of theoretical and simulation results,a test prototype was made and tested.The effects of the excitation magnet ratio,excitation distance,spring stiffness of the rebound spring and buffer spring,cam lift and lift angle on the output voltage and amplitude-frequency characteristics of the generator were obtained.And the best structural parameters were selected for the test of output power.The test results were consistent with the theoretical analysis.It proves the feasibility of the designed piezoelectric generator. |
