Research And Test Of Environmental Vibration Energy Harvesting Using Hydro-electric Approach

Sometimes, however, the vibration has negative effects on human bodies, machines and equipments. For this reason, most of people regard the vibration as a harmful energy. To control unwanted vibration, different vibration suppression devices have been developed to transform the vibration energy as acoustic or thermal energy for dissipation to the environment. In this way, the vibration energy is wasted. In addition, the energy transformation results in noise or thermal pollutions to the environment. If the dissipated vibration energy can be harvested effectively, one can not only save the energy, but reduce the environmental pollution as well. Moreover, the vibration energy exhibits high density without any pollution. All the above characteristics show that the vibration energy harvesting is a promising research field.Based on both the energy saving and the environmental protection ideas, this thesis proposes a hydro-electric energy harvesting approach for the environmental vibration. Through theoretical analysis, mechanism modeling, prototyping, and test rig building, a three-phase multi-signal excitation method is suggested to identify the model parameters. With the energy harvesting experiments, the harvesting capability and the influences of frequency and load are investigated. To further improve the energy harvesting performance, a rectified hydro-electric approach is presented. The prototype device based on the improved approach is fabricated. Vibration energy harvesting experiments are carried to compare with the original energy harvester. The contents of the thesis are as follows.(1) Through hydraulic cylinder-controlled motor for electricity generator, the vibration energy is harvested as electrical one. From the researches including mechanism analysis, theoretical modeling, prototyping, model parameter identification, and experimental testing, one may observe that the energy harvesting capability increases in response to the improvement of the vibration frequency. However, the harvesting capability will be dropped in the higher frequency band. The harvesting voltage increases in response to the enlarged load. When the load approaches the internal resistance of the generator(i.e., resistance matching), the generator produces the maximum power. During the experiments, the maximal instantaneous power 5.12 W is obtained at a sinusoidal vibration excitation 2Hz and 10 mm, with a load 2?.(2) The original prototype exhibits low energy harvesting voltage, small generation power and effectiveness, and unstable response resulting from the reverse of the generator. Hence this work introduces a hydraulic rectifier for the hydro-electric transmission to change bidirectional rotation as unidirectional one and to eliminate backlash of the reverse. In addition, the DC generator of the original prototype device is replaced by an AC one. An improved prototype device with the rectifier is accordingly fabricated.(3) Through the energy harvesting experiments on the improved prototype, one may observe that the harvesting capability is enhanced with the increased vibration amplitude. When fixing the load and the amplitude, the harvesting capability increased in response to the enlarged frequency. Afterwards a descending trend can be observed. The harvesting power is correlated to the load, whose optimal version is 15? measured in the experiments. Comparing to the original prototype, the optimal harvesting efficiency of the improved prototype is 20.57% occurring at the frequency 0.5Hz and the amplitude 25 mm. This efficiency is 1.65 times of the original prototype under the same excitation condition. The results show that the improved structure is effective for the vibration energy harvesting. The voltage that the improved prototype produced can light the bulb, which proves that hydro-electric approach has practical value.