Research On Energy Harvester Used In Roads Based On Piezoelectric Effect

There is enormous mechanical energy in roads. Harvesting and storing energy from roads is consistent with the concept of low carbon environmental protection, which can also reduce the structural damage caused by the energy accumulation in roads. In this paper, the structure of the piezoelectric energy harvester and the harvesting circuit are designed via the theoretical analysis and simulation analysis methods. An experimental platform of energy harvesting system is set up and the experimental study on the harvesting performance is carried out.To design an energy harvester coupling well with roads, kinds of commonly used structures of energy harvesters are analyzed and it is found that Cymbal type energy harvester has a high load carrying capacity, but its resonant frequency is quite high. Thus, the structure of Cymbal harvester is improved to form a novel arch structure which has a lower resonant frequency and has a relatively high stiffness.In order to obtain the influence of structural parameters on the generating performance of the arch energy harvester, the impacts of geometrical parameters on the output voltage and its resonant frequency are exploited through finite element method. The relationships between output voltage, current, power and load impedance and vibration frequency are also analyzed. Considering the analysis results the optimum structural parameters of the energy harvester are determined.To transform the alternating output voltage of energy havester into direct votalge, an energy harvesting circuit is designed. The working process of the energy harvesting circuit is analyzed. The output voltage, output power and input resistance are deduced theoretically. The simulation analysis of the energy harvesting circuit is carried out by using the Simulink module in Matlab. The influence of duty ratio, switching frequency and inductance value on output voltage is obtained. Using the analysis results, the energy harvesting circuit is designed and manufactured.Based on the simulation results and the characteristics of the road loads, prototypes of the arch piezoelectric energy harvester with different structure parameters are manufactrued. The influences of external force, load impedance and geometric parameters on the output voltage are analyzed. It is found that the maximum output power of 61 m W of for one arch energy harvester occurs at an external force of 10 N, with a frequency of 15 Hz and across an optimum matched impedance of 100 k?.