Research On Wind-induced Piezoelectric Vibration Energy Harvesting And Storage Technology

Wireless sensor networks have been widely used in environment monitoring, and to replace batteries for the sensors may be difficult. Applying self-powered technology in wireless sensor networks in forests has drawn many concerns, including several kinds of environmental energy, such as solar energy, wind energy, thermal energy and so on. Although the way of electromagnetic generator technology is mature, piezoelectric way has been investigated worldwide due to its good capability of generating electricity, simple structure and easy matching characteristic. In this paper, piezoelectric energy harvesting based on wind-cup structure was used, which can lay foundations for wind-induced multi-direction piezoelectric energy harvesting technology.The main research contents and related results are as follows:1. The characteristic of forest wind was analyzed, which was based on the wind speed and wind direction datas in the entrance of the Jiufeng forest. The distributions of wind speed and direction of every month in a year can be seen from wind rose plots. By data fitting, the Weibull probability density function of wind speed and Gaussian probability density function of wind speed were given. The results showed that the fitting degree of Gaussian probability density function of wind speed was higher. After certain tests, the Gaussian probability density function of wind speed was used to evaluate the wind energy. It’s feasible to collect the wind energy in low wind speed and piezoelectric vibration energy harvesting structure shoud be designed in multi-directions.2. The wind-induced piezoelectric energy harvesting structure based on cantilever beam was analyzed using ANSYS. Experiments of two modes of vibration were carried out to find the performance of each mode. Electrical energy collection experiment was made using the mode which had good performance in low frequency conditions. The results showed that the performance of collecting electrical energy was good using 3588-1 energy harvesting chip and film cell CBC3112, and the output voltage of CBC3112 can be from 2.06 V to 3.90 V in about 5 minites.3. Parametric analyse of standard interface circuit, series synchronized switch harvesting interface circuit, parallel synchronized swtich harvesting interface circuit and synchronized charge extraction interface circuit were carried out. The harvesting performance of the 4 different circuits under different load resistances was analyzed. The results showed that the parallel synchronized switch harvesting interface had better performance. An optimization simulation analysis was introduced, which could save time to optimize the parameters of the components in the circuit. Considering the randomness of the wind, the electrical energy collecting performance of four interface circuits was analyzed under random signals instead of sinusoidal signals. The results showed that the synchronized swtich harvesting interface circuit had better performance. An improved self-powered parallel synchronized swtich harvesting interface circuit was proposed and detailed analysis was made to analyze its working principles, and experiments were carried out.4. The system experiment was made. The results showed that the wind-cup piezoelectric energy harvesting device can be started when the wind speed is above 3.5 m/s, and the randomness of wind resulted in the large fluctuations. The available wind energy from the wind cup structure can make the piezoelectric patch produce deformation, and by using the improved parallel synchronous switch harvesting interface circuit and super capacitor to collect and store the energy, the energy conversion rate reached 14.5%.This research results can provide a new insight for developing the self-powered wireless sensor networks, different from the traditional electromagnetic way, which will provide technical foundations for the wind-induced multi-direction piezoelectric vibration energy harvesting.