High-Efficiency Piezoelectric Energy Harvester Design And Performance Analysis For Intelligent Pavement

In order to accelerate the implementation of a strong transport nation,develop smart roads and advocate green transport.Converting the huge amount of road vibration energy into electrical energy by using the force-electric coupling characteristics of piezoelectric ceramics.This is consistent with the development demands of the new age for low carbon,environmental protection and energy saving.However,pavement power generation technology still faces challenges such as low energy conversion efficiency and complex traffic load variations,which limit the application of piezoelectric ceramics in pavement power generation.In this dissertation,piezoelectric ceramic materials and the structure of energy harvester were discussed.Firstly,piezoelectric ceramic materials with high energy conversion coefficient were prepared,and the power generation efficiency of energy harvester was studied based on theoretical analysis and finite element simulation.Finally,the energy harvesting characteristics of the designed pavement energy harvester were experimented under the influence of vehicle speed,load and electrical circuit.This will help to provide a potentially new type of renewable energy source along the road.（Ba1-x Cax）（Zry Ti1-y）O3 lead-free piezoelectric ceramics were prepared by traditional solid-state method at 1400℃.The effects of composition on the microstructure and electrical properties of the ceramics were analyzed by changing the content of Ca and Zr,respectively.The best performance of the BCZT system was obtained when the composition ratio of the ceramics was（Ba0.85Ca0.15）（Zr0.1Ti0.9）O3.Based on this,Cu O was added as a dopant and sintering aid to(Ba_0.85Ca_0.15)(Zr_0.1Ti_0.9)O₃,and the traditional solid-state method was used for sintering at 1250℃.The dielectric and piezoelectric properties increased with increasing Cu O content under a small amount of Cu O doping.BCZT-x Cu has the best performance when x=1 wt%:d₃₃=315 p C/N,k_p=34%,ε_r=3213,tanδ=2.71%.A new quaternary lead-based piezoelectric ceramic x Pb（Fe0.5Nb0.5）O3-（0.57-x）Pb（Ni1/3Nb2/3）O3-0.43Pb（Zr0.3Ti0.7）O3 was prepared.The variation regulation between microstructure and electrical properties was investigated.In order to obtain piezoelectric ceramic materials with high electrical constants,the phase structure of the ceramics was induced near the MPB by component modulation.It was demonstrated that with the PFN content of 0.045,the phase structure was observed near the MPB where the R-T phases coexist.Also,the best electrical properties were obtained:d33=961 p C/N,kp=0.716,ε_r=6298 and tanδ=3.1%.The d₃₃×g₃₃ values of(Ba_1-xCa_x)(Zr_yTi_1-y)O₃,BCZT-x Cu and xPFN-PNN-PZT piezoelectric ceramics were compared.The conversion coefficient of lead-based PFN-PNN-PZT piezoelectric ceramics is much higher than lead-free BCZT system ceramics,and xPFN-PNN-PZT is more suitable for energy harvester applications.Furthermore,the finite element software is used for numerical modeling to explore the influence of structural parameters on the dynamic characteristics and electromechanical characteristics of the cantilever piezoelectric energy harvester,including the bonding position of the piezoelectric ceramic,the length-width ratio and thickness of the cantilever beam.Based on the simulation results,the xPFN-PNN-PZT piezoelectric ceramic cantilever energy harvester was fabricated and tested by building a vibration energy harvesting platform.The results show that the open-circuit voltage increases with the increase of the excitation acceleration.The 0.045PFN-PNN-PZT ceramic obtains a maximum voltage of 28.4V at 5g acceleration.The measured energy density of0.045PFN-PNN-PZT piezoelectric ceramic is up to 3.95μW/mm³.A new road piezoelectric energy harvester is designed to avoid the damage of piezoelectric ceramics by magnetic force.Based on the research results of road vehicle power generation theory,the new road piezoelectric energy harvester is tested by different speeds,different loads and different interface circuits.The experimental results show that with the increase of vehicle speed,the peak voltage before and after rectification also increases,but the voltage interference becomes more and the stability decreases.With the increase of load,the collected energy increases first and then decreases,and the maximum energy of 2.73 m J is obtained under the optimal load of 10 km/h speed in SEH circuit.With a speed of 10 km/h and a resistance of 20 kΩ,the output energy of the SSHC can be increased up to 66.3%compared to the SEH circuit.At the optimum load of 40 kΩ,the peak energy output SSHC is 11.3%higher than SEH.