Research On Vibration Energy Harvesting Of Vehicles Based On Piezoelectric Effect

The development of energy conservation in vehicles is attracting increasing attention due to the consumption of fossil fuels.Energy harvesting during operation has become an important strategy to increase the endurance mileage and reduce the emission.One of the energy sources that can be recovered is the vibration energy of the vehicles.In this dissertation,we focus on vibration energy harvesting and solving key technologies in vehicles by using the piezoelectric effect.The vibration energy harvesting system is modeled and optimized.Average power is calculated based on proposing virtual displacement filtering algorithm.Key factors are studied in order to maximize the recovery power.An efficient and stable recovering method is proposed.The main research contents and achievements are as follows:Aiming at the key technology of modeling the vibration energy harvesting system using piezoelectric effect in vehicles,a recovery way to excite the layered piezoelectric cantilever beams by gear is proposed,and an overall design of energy harvesting system is carried out.The reasonable parameters of a single piezoelectric bending element are discussed by using the mathematical model.The first-order and third-order modes,the eigenfrequency,and the resonance frequency of a single piezoelectric element are obtained by simulation.A reasonable topology is also obtained by analyzing the models of series and parallel topology.The mechanism is decomposed into parts,modeled and designed separately.Upon the above,the overall model of energy harvesting system is built,which proves the accuracy by simulation.A virtual displacement filtering(VDF)algorithm for calibrating the average power of piezoelectric harvesting is proposed by analyzing the excitation of the first-order and third-order modes,which improves the calculation accuracy of average power comparing to the limiting filtering and five-point smoothing filtering algorithms.The algorithm is used to filtering the parts of displacement which can not excite the piezoelectric bending elements and cause the deviation of average power.On the basis of filtering,the average power calculation method is derived.A simulation is carried out to test the influence of different excitation modes,filtering methods and gear pitches.In order to gain the maximum power and good robustness of the energy harvesting system,road surface is constructed and vibration displacements under various tolerance levels are simulated through the simulation platform.The influence of road tolerance grade,vehicle speed and the value of gear pitch are studied individually.The method of determining the gear pitched and the switching principle based on double-gear exciting mechanism are proposed.On the basis of theoretical research,the recovery power simulations are carried out to study the effectiveness of the double-gear excitation.Additionally,the experiments of average power measurement,recovering power test and double-gear switching verification are designed with building a test bench of piezoelectric energy harvesting.The effectiveness of the theoretical method is verified through the analysis of the experimental results.