Research On Multi-Directional Piezoelectric Wind Energy Harvester And Its Application

With the rapid development of the Internet of Things,wireless sensor networks have been widely used in many fields,such as forest fire monitoring,precision agriculture,and battlefield assessment.As a potential power source for wireless sensor network nodes,energy harvesters based on wind-induced vibration have attracted more and more attention.Most of the wind energy harvesters reported so far have a single working wind direction,and they are susceptible to performance degradation due to environmental influences.In addition,there is less research on self-powered wireless sensor nodes suitable for relative long distance transmissions.Therefore,it is of great significance to carry out research on multi-directional wind energy harvesters and self-powered wireless sensor nodes driven by them.To solve the problems of unstable output of existing wind-induced vibration wind energy harvesters when the wind direction changes and poor stability during long-term work in the field,this thesis proposes a multi-directional piezoelectric wind energy harvester with a protection device,and one self-powered wireless temperature and humidity sensor node with low energy consumption is designed based on the harvester.The performance of the multidirectional piezoelectric wind energy harvester and the self-powered wireless sensor node was tested.The main work includes:(1)The multi-directional piezoelectric wind energy harvester with protection is proposed to overcome the shortcomings of current wind energy harvesters and satisfy the needs of practical applications,it can not only harvest wind energy in multiple directions,but also has good stability in field work.(2)The work process of the multi-directional piezoelectric wind energy harvester was introduced,established a preliminary model of the harvester,and analyzed the vibration mode of the harvester.(3)The prototype of the harvester was fabricated,and the influence of the width of the beam and the height of the bluff body on the performance of the harvester was explored through experiments.Harvesters with square,octagonal and circular bluff body shells were tested on different wind directions,the results show that the harvester with circular bluff body shell can harvest wind energy in any direction in the plane.(4)The power management circuit of the multi-directional piezoelectric wind energy harvester was designed,the wireless temperature and humidity sensor node based on Zig Bee was also designed,which was deeply analyzed on power consumption of each part in the normal operation.Meanwhile,the method to reduce the energy consumption of the wireless sensor node was given.The final wireless sensor node consumes 9.347 m J of energy for one data transmission,and the communication distance can reach to 150 m.(5)Wireless sensor node circuit board was designed and the QT application development framework was used to build the upper monitor interface.The wireless sensor node driven by the multi-directional piezoelectric wind energy harvester was tested in the wind tunnel.The results show that the output power of the harvester is 131.6μW at a wind speed of 8m/s,and the temperature and humidity data was sent every 1376 s.