Design And Realization Of Low-frequency And Wideband Vibration Energy Hravester

Ambient vibration energy, as a common form of energy, extensively exists in large industrial and mining equipment, transportation equipment, large construction projects like bridges and highways, as well as life activities of organisms. The micro-nano monitoring device can be powered by the vibration energy in harvesting environment, which is of great research significance and practical value in addressing the stable supply of power for electronic monitoring device in particular environmental conditions(such as high noise and vibration, wilderness, and micro-bioenviroment). Meanwhile, a new idea on research is offered by the research of environmental energy harvesting system in order to solve the problems of traditional energy providing approach(for example, chemical batteries), such as big volume, a limited lifetime, and the polluted environment.The ambient vibration is of the characteristics of tiny acceleration amplitude,low frequency(<200Hz) and wide band, and generally behaves as the interaction of several vibration. However, the requirement of present vibration energy harvesting can not be satisfied by traditional energy harvester in virtue of high resonant frequency and narrow working band. For tackling above problems,the multi-degree-of-freedom vibration energy was proposed in this paper, which achieved energy harvesting of multi-model and wide-frequecy in low-frequency range(<100Hz).(1) The present self-powed problems for the micro-nano sensors in particular circumstances were summarized and the three kinds of traditional vibration energy harvesting including electrostatic type, piezoelectric type and electromagnetic type were introduced. Then the latest development trends of piezoelectric vibration energy harvesters, their advantages and disadvantages in the typical researches were analyzed emphatically. Based on those analyses, the demands for the low-frequency and wideband energy harvesting structure were proposed.(2) The theoretical basis of piezoelectric energy harvester was studied,including the basic conception of piezoelectric effect, piezoelectric materials and their performance parameters, as well as piezoelectric equations. And the electromechanical conversion features, spectrum properties and performance deficiencies of traditional cantilever vibration energy harvester were analyzed theoretically.(3) The kind of linear multi-degree-of-freedom piezoelectric energy harvester was designed, and the mathematical model was built to carry on theory analysis.And the finite elements software COMSOL was adopted for simulation. The results showed that each order resonant frequency was decreased significantly with the system’s vibration degree-of-freedom increasing. In the range of0-200 Hz, the linear multi-degree-of-freedom energy harvester could achievemultiple vibration modes which were close or connected, broadening the frequency band effectively.(4) The testing platform for energy harvesting system was set up. The open-circuit voltage and power of the fabricated linear energy harvester of single-degree-of-freedom, two-degree-of-freedom and three-degree-of-freedom were tested. The experimental results indicated that the proposed three-degree-of-freedom harvester could reach up to 15Hz(375% of single-degree-of-freedom structure). Meanwhile, its maximum output power could be 82.4μW at the first mode, and it can attain output power at other three vibration modes. These performances enable the multi-degree-of-freedom system to improve viability for scavenging energy from multi-source and wide-frequency vibration environment.