| With the development of society and technological progress,micro smart devices are widely used in various fields,but the problem of power supply has become a major bottleneck that restricts their development.To solve this problem,researchers have started to explore how to obtain energy from the environment,such as solar energy,wind energy,vibration energy and thermal energy.However,compared with other energy sources,vibration energy has the advantages of wide range of existence and is not affected by the environment and is widely concerned.On the one hand,among the three common vibration energy harvesting methods,piezoelectric,electromagnetic and electrostatic,piezoelectric vibration energy harvesting devices are simple in structure,easy to operate and have high energy density.On the other hand,the vibration energy harvesting device designed based on piezoelectric cantilever beam has the problems of restricted excitation direction and narrow operating frequency band.In this context,this paper designs a vibration energy harvesting device with multi-directional and wide frequency domain operating characteristics,which works as follows:(1)A piezoelectric vibration energy harvesting basic module is designed,which has two different forms and will be subsequently arranged in pairs to improve the problems of restricted excitation direction and narrow operating band of the conventional piezoelectric cantilever beam.According to the designed energy harvesting basic module,a detailed finite element model is established,and the optimization analysis of parameters such as structure size,substrate tilt angle and piezoelectric material attachment point is completed to determine the final parameters of the energy harvesting module,and the output characteristics of the optimized energy harvesting module are further analyzed.(2)Based on the vibration energy harvesting module,a spatial layout scheme with central circumferential symmetry is proposed.In addition,to further improve the response dimension and efficiency of the vibration energy harvesting device,a spring support structure that can form multi-directional excitation for the basic module is designed,thus establishing a preliminary model of the vibration energy harvesting device.Through the theoretical analysis of the piezoelectric vibration energy harvesting device,the output characteristics of each piezoelectric module on the vibration energy harvesting device are clarified,and the spring support structure is ensured to meet the working requirements.On this basis,a finite element model of the piezoelectric vibration energy harvesting device is established,and the effects of chassis stiffness and spring member parameters on the output characteristics of the device are analyzed,and the piezoelectric vibration energy harvesting model is determined based on the analysis results.Finally,the output characteristics of the energy harvesting device are studied,and the results show that the device has good output characteristics with multiple large response peaks when it is excited by different directions.(3)The processing and fabrication of the vibration energy harvesting device model and the vibration test platform were completed.Firstly,the output characteristics of the piezoelectric vibration energy harvesting device were tested,and the test data of the piezoelectric vibration energy harvesting device were compared with the simulation results,and the two were in good agreement.Secondly,the output characteristics of the piezoelectric energy harvesting module were tested under different excitations,and the test data were in high agreement with the theory.Finally,comparing the test data of the vibration energy harvesting device under different directions,the results show that the vibration energy harvesting device designed in this paper has multi-directional and wide frequency domain vibration energy harvesting characteristics,which further verifies the effectiveness and feasibility of the design scheme in this paper. |
