Simulation And Experiments Of Broadband Piezoelectric Energy Harvesting Devices

The critical orientation of researching is how to transmit the remote terminal signals without wiring, owing to the emergence of wireless sensor networks which based on wireless transmission mode have brought a new life for this technology. However, one of the important factors to limit the wireless transducer network application is the power supply for the remote terminal nodes, this is caused by the limited battery power supply, replacement challenge and poor environmental adaptability. In recent years, with the development of sensor technology, it becomes much more practical question of how to absorb the energy from ambient sources, especially the ambient vibration energy.There are many kinds of vibration energy existed in natural environment which can be one of most important energy source for wireless sensor networks power supply system. This job was financially supported by the National Science Foundation of China general projects and the projects researched by China Natural Science Foundation of the Anhui Province Higher Education Institutions. In this paper, we further researched on the key technology of piezoelectric vibration energy acquisition, then we presented the development of the narrow bandwidth and poor efficiency of conversion and storage circuit. After those work we used the theoretical calculation, simulation and experiments to verify the feasibility of improved measurements.The main research contents of this paper are as follows:(1) We have analyzed the working principle of energy acquisition device, which was made from a piezoelectric bimorph cantilever beam with multiple mass at the top of the beam, then we establish the mathematical model of this beam and analyses the influence of the number and location of mass to the piezoelectric cantilever’s resonant frequency and power performance. The result shows that:the resonance frequency of piezoelectric cantilever can be effectively reduced and the output voltage and power is increased with the increasing number of mass at the top of the beam, with closer distance to the free end of the cantilever cantilever beam, the frequency will be better reduced.(2) The analytical model of cantilever beam is built in ANSYS. We use the post-processing module in ANSYS to research the influence regulation of piezoelectric oscillator’s parameters and the number of mass to the generated voltage by static analysis, model analysis and harmonic response analysis. The simulation results show that:the output voltage of cantilever is increased with its length increment; decreased with the width increment; with the increased thickness of PZT, the output voltage is increased first and then decreased, the maximum value appeared in0.6-0.8times of the substrate. Thinner central inner copper layer will create higher voltage. With the increasing numbers of mass, the resonant frequency is reduced and bandwidth is expanded. The finite element analysis results are coincided with the theoretical analysis results.(3)We presented the development of bridge rectifier circuit to optimize the traditional one, which combines diodes and inductors into the circuit to improve the efficiency and output power of acquisition device.(4) An experimental system is setup to measure the output voltage and power of the PZT cantilever under a vibration excitation. The experiments results are consistent with the theoretical analysis and finite element analysis results.