The Energy Harvesting Performance Of D₁₅ Model Laminated Structure Cantilever In The Environment With Low Frequency

With the rapid development of super large scale integrated circuit design technology and MEMS technology, the power consumption of microelectronic device becomes increasingly low for the characteristic size continuously reducing, the power consumption of some microelectronics devices such as wireless sensor has reached ?W level. Capturing the energy from the natural environment and converting into electricity,The mechanical vibration energy is ubiquity in the environment. According to the polarization direction, deformation direction and electric field direction of piezoelectric material, the piezoelectric energy harvester?PEH? have three kinds of modes, d₃₃, d₃₁ and d₁₅ respectively. Generally speaking, the piezoelectric coefficient of piezoelectric materials is higher, the output power and voltage of the PEH is greater. The d₁₅ coefficient is greater than d₃₃ and d₃₁ coefficients of some typical piezoelectric materials. Therefore, the d₁₅ model PEH is expected to improve the performance of the PEH. Vibration frequency of vibration source in natural environment is distributed in the range of 20 to 200 Hz, Capturing the vibration energy with low frequency from the environment is considered to be the key of devices design. In this paper, the performance of the d₁₅ model cantilevered PEH in parallel connection was studied by finite element model?FEM?, theoretical model and experiment. The main works is as follows:?1? We selected PZT-51 material with large shear piezoelectric coefficient d₁₅ as Piezoelectric element,then determine all parameters of the material. Based on the single degree of freedom model, the d₁₅ model of series laminated structure and parallel laminated structure is established. The energy harvesting performance of d₁₅ cantilever beam with laminated series and parallel piezoelectric layer structure under the same conditions were studied by the finite element software ANSYS. The results of theoretical calculation was good agreement with the results of finite element analysis method?FEM?, It means that the proposed model and finite element analysis method can provide guidelines for the energy harvesting performance analysis of d₁₅ model laminated structure cantilever beam.?2? The laminated series and parallel structure experimental facility of d₁₅ mode PZT-51 piezoelectric cantilever was established. The curves of output peak voltage and power varies with frequency were measured. The instantaneous output voltage with different load resistances was investigated at resonant frequency. In addition to we measured output voltage of series parallel bimorph structure cantilever beam with different vibration excitation voltage at the resonant frequency.The results are in good agreement with the finite element simulation results and theoretical analysis result, It shows series structure cantilever beam has higher output voltage in greater resistance load and parallel cantilever beam structure in low resistance load has higher output current. We hope those works can provide useful guidelines for the design of d₁₅ mode piezoelectric energy harvesters.?3? To research for the effects of piezoelectric layer thickness on energy harvesting performance of laminated structure cantilever beam, thed₁₅ model series laminated structure piezoelectric cantilever experimental devices, which of piezoelectric layer thickness were 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm respectively, were designed and fabricated. The curves of output peak voltage and power varies with frequency were measured at a given resistance, and the dependence of output voltage and power on different resistance at resonant frequency. And also, the curves of instantaneous output voltage versus time and the curves of output voltage versus the vibration table driving voltage were tested at load resistance of 1 M?. We can explore the impact of inherent frequency and energy harvesting performance of the devices by changing the thickness of the piezoelectric layer.