| With the continuous development and application of intelligent materials,the piezoelectric energy recovery technology,which uses the positive piezoelectric effect of piezoelectric materials to convert the mechanical energy of structural vibration into electrical energy,has become increasingly mature,with the advantages of energy conservation and environmental protection,easy miniaturization and wireless power supply.At present,piezoelectric vibration energy collection device mainly includes cantilever,disc,plate structure and stacking structure.The above various forms of piezoelectric vibration energy collection system can achieve the energy capture effect under the specific low-frequency environment,but for the high-frequency vibration in the real environment,the vibration energy in the structure is in a decentralized state,which will greatly increase the difficulty of piezoelectric energy collection and reduce the energy conversion efficiency.Extended from the concept of "black hole" in physics to the field of acoustics,the acoustic black hole structure formed has a good control performance for the incident wave.Based on the basic characteristics of acoustic black hole,a piezoelectric array energy collection system based on imperfect acoustic black hole structure is established in this paper,which is used to solve the problem of low energy recovery efficiency of piezoelectric vibrator under high frequency harmonic excitation.Firstly,the basic principle and characteristics of one-dimensional acoustic black hole structure are analyzed in theory,and the finite element model of not perfect acoustic black hole thin plate structure is established in combination with the limiting factors under the actual processing conditions;the energy accumulation characteristics in the truncated region of the model are analyzed,and the experimental model of the array piezoelectric energy capture system is designed,and the voltage characteristics such as phase difference of the output of a single piezoelectric vibrator in the system are analyzed,amplitude,etc.Finally,based on the superposition principle,the bridge rectifier is introduced into the interface circuit of the system,and the connection test of the multi piezoelectric vibrator is carried out through the experimental method,as well as the experimental analysis of the optimal load resistance of the system.The main work of this paper is as follows:(1)This paper introduces the current situation and progress of piezoelectric energy recovery and acoustic black hole research at home and abroad.Through comparative analysis of the current research and design of piezoelectric energy recovery system device,there are limitations such as limited frequency range and insufficient efficiency.Furthermore,the research status of energy recovery system based on acoustic black hole structure is introduced.The research of structure design and interface circuit optimization is analyzed.The application of piezoelectric energy recovery technology in high frequency excitation environment is extended.(2)Based on the theoretical derivation of the perfect acoustic black hole structure effect,this paper analyzes the imperfect acoustic black hole structure effect in the truncated region,and analyzes the characteristics of the amplitude and wave number of the bending wave by the reflection of the bending wave in the truncated region.The theoretical analysis of piezoelectric material’s positive piezoelectric effect,combined with the structural characteristics of imperfect acoustic black hole,can make up for the defects of traditional energy recovery technology in the frequency range,and improve the efficiency of energy recovery.(3)An accurate simulation model is established to compare the kinetic energy density and the output voltage of the structure.The energy nephogram in frequency domain and time domain is analyzed,and the propagation characteristics of bending wave in acoustic black hole structure are obtained.Based on the finite element simulation analysis,the piezoelectric vibrator on the center platform of the model is arranged,and the array piezoelectric vibrator energy capture system is designed to solve the problem of mutual cancellation between the energy accumulation points in the traditional imperfect acoustic black hole structure.(4)Set up the simulation platform,select multiple groups of high-frequency excitation sources,carry out the simulation experiment of piezoelectric energy capture,comprehensively compare the output voltage characteristics of single and multiple piezoelectric oscillators in the system,and analyze the influencing factors of the output power of piezoelectric energy capture.The output voltage and power characteristics of four circuits and multiple load resistances are compared and analyzed.In order to improve the output power of piezoelectric energy capture system,the optimal external load resistance of multiple interface circuits is determined. |
