Abstract
Vibration energy harvesting is to transform the ambient mechanical energy to electricity. How to reduce the resonance frequency and improve the conversion efficiency is very important. In this paper, a layer-separated piezoelectric cantilever beam is proposed for the vibration energy harvester (VEH) for low-frequency and wide-bandwidth operation, which can transform the mechanical impact energy to electric energy. First, the electromechanical coupling equation is obtained by the Euler-Bernoulli beam theory. Based on the average method, the approximate analytical solution is derived and the voltage response is obtained. Furthermore, the physical prototype is fabricated, and the vibration experiment is conducted to validate the theoretical principle. The experimental results show that the maximum power of 0.445 □W of the layer-separated VEH is about 3.11 times higher than that of the non-impact harvester when the excitation acceleration is 0.2 g. The operating frequency bandwidth can be widened by increasing the stiffness of the fundamental layer and decreasing the gap distance of the system. But the increasing of operating frequency bandwidth comes at the cost of reducing peak voltage. The theoretical simulation and the experimental results demonstrate good agreement which indicates that the proposed impact-driving VEH device has advantages for low-frequency and wide-bandwidth. The high performance provides great prospect to scavenge the vibration energy in environment.
Highlights
Energy harvesting technology refers to transform the ambient energy, such as solar, heat, sound, wind, and vibration, into electrical energy and store in capacitor or battery in a variety of ways
The red dotted curve shows the theoretical result and the blue triangular curve is the experimental result of the proposed harvester with k2 = 388.8 N/m and d = 0.5 mm while the pink solid curve shows the theoretical result and the black dot curve is the experimental result of the original harvester
Some errors occurred in the experimental results, the waveform curve of the open circuit voltage and the performance of broadening the operating frequency bandwidth and improving the peak voltage agreed well with the theoretical results
Summary
Energy harvesting technology refers to transform the ambient energy, such as solar, heat, sound, wind, and vibration, into electrical energy and store in capacitor or battery in a variety of ways. It is found that the harvesting efficiency of the vibration energy in the environment is as high as 25%–50%. The piezoelectric vibration energy harvesting (PVEH) attracts broad attention because of its advantages of high conversion efficiency and easy integration for microelectromechanical systems. It becomes significant to broaden the response bandwidth and improve the conversion efficiency for the VEH. To achieve this goal, scientists developed many kinds of oscillators based on linear and nonlinear vibration theory, such as bistable models[11,12,13], multistable models[14,15,16], and multidegrees models[17,18]. There are stochastic excitation VEHs[19,20,21] and nonlinear internal resonance VEHs[7,13,22]
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