Research On Piezoelectric And Electromagnetic Compound Vibration Energy Harvesting Based On PVDF

Vibration energy harvesting technology aims to convert the mechanical energy into electrical energy through piezoelectric effect or electromagnetic induction to supply energy for wireless sensors.In this paper,based on PVDF,a vibration energy collector who coupled piezoelectric effect and electromagnetic induction was designed,and it was studied from the aspects of multi-physical field and energy collection circuit.The static model of fixed beam was established,the basic principles of piezoelectric effect and electromagnetic induction were analyzed,and the process of making PVDF film by flow extension method was introduced.The spring-mass-damping model was established from the dynamic point of view,and the expression of the permanent magnet's amplitude was derived.The equivalent circuit models of piezoelectric unit and electromagnetic unit were established from the electrical point of view,the output power expression was derived,and the coupling effect between them was analyzed.The finite element model of the piezoelectric unit was established,and the frequency domain response analysis and impedance matching analysis were carried out with the COMSOL simulation software.The influence of the base thickness,the piezoelectric element's thickness and other parameters were explored.For the electromagnetic unit model,the influences of single or double coils,coil size,coil and permanent magnet spacing on the induced voltage were analyzed.Piezoelectric and electromagnetic compound system was analyzed in frequency domain response,the output power was 3.24 m W under 1g acceleration load and 500k?.The characteristics of nonlinear system were studied,and the electrical output of piezoelectric and electromagnetic units under different magnetic fields were investigated.The temperature field was introduced to study the working conditions of piezoelectric units to ensure their environmental adaptability.The working state of the piezoelectric unit was studied from the micro scale,and the changes of its resonant frequency and output power density were analyzed.The piezoelectric energy harvesting circuit based on voltage comparison chip MAX6433 and voltage regulation chip MAX666 was designed.It could periodically output a voltage of 3.25 V.The LTC3588-1 chip was introduced to design an energy harvesting circuit with voltage rectifier and voltage regulator function for the electromagnetic unit,which achieved a stable output of 3.3V.Combined with two sub-circuits,the piezoelectric electromagnetic composite energy harvesting circuit was designed,with the open circuit output voltage up to 6.55 V and the output power up to 2.21 m W.In this paper,PVDF flexible film was used to overcome the weakness of traditional piezoelectric materials,piezoelectric electromagnetic composite power generation was used to improve the electromechanical conversion efficiency,and nonlinear system was used to broaden the energy collection frequency band,which has certain reference value for the research in the field of vibration energy harvesting.