Research On Design And Performance Of A Direction Self-Tuning Two-Dimensional Piezoelectric Vibration Energy Harvester

Energy supply has always been a key issue in determining the development of modern society.People are always looking for clean and sustainable energy to replace traditional burning fossil resources.In recent years,energy harvesters that directly obtain energy from the environment have been widely used.Including applications in a variety of civilian and military devices.Among them,the most prominent role of the energy harvester is to power various wireless sensor nodes.Because these wireless sensors are usually widely distributed,many in number,and are mostly used in various unmanned areas,they are remotely located.If wiring or battery replacement is used to maintain the working life of the device,the maintenance costs caused are too high,and the operation is difficult.Therefore,how to supply power to high-density nodes in the Internet of Things has become a key issue limiting its development.Traditional energy harvesting technologies include solar,wind,thermal,and vibration mechanical energy harvesting technologies.Among them,piezoelectric vibration energy harvesters designed using the positive piezoelectric effect of piezoelectric materials have been widely used in recent years.It has many advantages such as simple structure,high energy density,and easy miniaturization.However,due to the diversity of vibration sources,the direction of excitation vibration is often random and changeable,and most traditional cantilever beam vibration energy harvester which has a good effect of collecting vibration energy only in a specific excitation direction.Once the excitation vibration direction deviates from the direction of the bending strain of the cantilever beam,the energy output decreases significantly.To solve the problem of single collection direction of the traditional fixed cantilever piezoelectric harvester,this work proposes a rotatable cantilever piezoelectric energy harvester,which applies the elastic force generated by the vibration deformation of the spring to drive the cantilever with bearings to rotate.The plane of the piezoelectric unit is always perpendicular to the vibration direction,and the vibration mechanical energy is converted into electrical energy in the piezoelectric effect d-33 working mode.Compared with the traditional fixed cantilever beam harvester,it can effectively collect the vibration excitation energy in any direction in the two-dimensional plane by adjusting the working plane of the piezoelectric unit,and the output voltage is higher.The specific research work of this article is as follows:1.A directional self-adjusting two-dimensional piezoelectric vibration energy collector is proposed,which mainly includes a stainless steel cantilever beam,a lightweight spring-mass system,and acrylic rotating arm,and other supporting frames.A theoretical model was established for this type of self-adjusting cantilever beam structure and vibration dynamics analysis was performed.The results show that the cantilever beam can achieve self-adjusting direction under the action of the elastic moment,and the harvester is modularized by ANSYS simulation software.Analyze the harmonious response analysis and study the vibration characteristics of the collection system.2.A comparative experiment was designed for the two structures of traditional fixed cantilever vibration energy harvester(C-PVEH)and directional self-adjusting two-dimensional piezoelectric vibration energy harvester(DST-PVEH).The output voltage under directional excitation,according to the experimental test results: Without the introduction of a rotating arm,the open-circuit voltage output of C-PVEH gradually decreases with the increase of the deflection angle ?,but DST-PVEH can be used at any ? keeping the same high voltage output,the average output voltage is about 12 V.Therefore,by using the rotating mass generated by the vibration deformation of the spring-mass system to drive the rotating arm to adjust the working plane of the piezoelectric unit,a possible solution for multi-directional vibration energy collection is provided.3.The effects of vibration excitation acceleration and deflection angle ? on adjustment time were further explored in detail.The experimental results show that the greater the acceleration of the vibration excitation,the faster the adjustment process,and the shorter the adjustment time required.By connecting the PVDF piezoelectric film with a 22?F constant capacitor,and observing and comparing the charging curve under different deflection angles and excitation accelerations,it can be seen that the required adjustment time is 130 s when = 0 ° and = 85 ° The adjustment time is 179.6s.The larger the initial offset angle,the longer the adjustment time is required.The final power test shows that under the output of a single PVDF piezoelectric unit,the optimal power output can reach 180?W,and the load at this time is 5.2M?.