Study On Equivalent Circuit Model And Energy Recovery And Conversion Circuit Of Piezoelectric Power Generation System

With the rapid development of Artificial Intelligence(AI)and The Internet of Things(IOT),various wireless sensors have been applied to all aspects of human life.People's requirements for batteries are getting higher and higher.The usage of traditional batteries has such disadvantages as short cycles,large pollution and difficulty in replacing in many cases.Therefore,there is an urgent need for a sustainable and environmentally friendly new mode of energy supply.Mechanical vibration energy exists widely in nature,and due to its few constraints,piezoelectric vibration energy collection has become a hot topic of experts and scholars.At present,for the research of piezoelectric vibration energy harvesters,collectors on the mechanical side are often reduced to a current source,and electrical terminal is simplified into the load.Although this greatly simplifies the analysis of energy harvester,this kind of treatment of cantilever piezoelectric ceramics with circuit between the electrical and mechanical nonlinear coupling resulting in large errors of experimental analysis results and the theoretical results.In addition,the research on the energy recovery performance of the cantilever piezoelectric energy collector is also based on equating the interface circuit to a load,which is bound to bring a large analysis error.This paper starts with the equivalent circuits of piezoelectric side,first establishes the equivalent circuit of the collector terminal through the lumped parameter model and piezoelectric equations of motion,and then studies and analyzes the specific interface circuit,and then analyzes the energy flow from the input to themechanical energy acquisition system of the end,the electric terminal,until the output terminal of the energy flow analysis,and establishes the acquisition system energy flow diagram,analyzing system under different interface circuit of energy flow,different circuit parameters are analyzed by simulation and experiment system to energy,energy dissipation and extract.The main contents of this thesis are introduced as follows:(1)The research status at home and abroad is introduced to understand the theoretical knowledge related to the content of piezoelectric vibration energy collector in this thesis,including piezoelectric equation,piezoelectric effect,etc.,so as to lay a theoretical foundation for the subsequent research and analysis in this thesis.(2)The structure and working principle of linear piezoelectric vibration energy collector are introduced.The lumped parameter model and motion equation of piezoelectric vibration energy collector are established based on the principle of force-electric balance.On this basis,electromechanical equivalent parameters are introduced,and the lumped parameter model is transformed into the equivalent circuit model of the piezoelectric energy collector.The parameters of the equivalent circuit model are identified by Rayleigh-Ritz modal analysis method,and the correctness of the equivalent circuit and its identified parameters is verified by experiments(3)According to the energy collector output signal characteristics and design standards for energy recovery(Standard),respectively self-energized SSSHI(SP-SSSHI),self-energized PSSHI(SP-PSSHI)three conversion interface circuit,analyzes the three kinds of structure and working principle of the circuit and process,under the condition of constant displacement amplitude at the end,using Pspice simulation study and analysis of different recycling power conversion circuit,and the research and analysis on the output waveform,and the circuit parameter optimization;Finally,the experimental platform is built,and the free load recovery power of different conversion circuits is studied and analyzed by using the platform,and the applicable scope of three conversion circuits is determined.(4)Considering energy collector of the mechanical structure and the coupling action between conversion circuit,from the point of view of energy flow analysis ofthe environmental vibration from the mechanical energy to the interface circuit and the output energy transport mechanism,and established the system respectively on the mechanical and electrical energy flow diagram,analyses the energy of each part and the influence of circuit parameters on each part of the energy law;Finally,the simulation results are verified by experiments.The results of this thesis provide theoretical and experimental basis for improving the output efficiency of piezoelectric vibration energy harvester and designing efficient energy conversion interface circuit.