Research On Resonant Cavity Piezoelectric Energy Harvester Driving Wind Pressure

With the development of new energy vehicles and smart cars,the number of onboard sensors are increasing.Currently,on-board sensors are powered by traditional chemical batteries.The performance of chemical batteries is greatly reduced in harsh environments.Based on the problem of traditional energy supply for sensors,this paper designs a resonant cavity piezoelectric energy harvester for application in “shared car” Geely Zhidou D2 to achieve the self-supplied energy of the sensor.The research content is as follows.First of all,according to the characteristics of driving wind pressure energy,three piezoelectric energy harvester structures are designed: resonant cavity piezoelectric energy harvester with spoiler cylinder,resonant cavity piezoelectric energy harvester with Helmholtz resonator and resonant cavity piezoelectric with both turbulent cylinder and Helmholtz resonator.Three structures of the energy harvester are simulated by Fluent.The results show that the energy harvester with the turbulent cylinder and Helmholtz resonator can generate greater pressure in the main cavity,so it is selected as the energy harvester based on driving wind pressure.Secondly,resonant cavity piezoelectric energy harvester has a range of effective working wind speed.The starting wind speed is solved by law of conservation of energy.The relationship between the wind speed and the maximum stress of the cantilever beam is researched to solve the cutoff speed.The results show that the starting wind speed is 5.29m/s and the cutoff speed is 25m/s.The energy harvester can work normally due to the range of working wind speed greater than travel speed of the shared car.And then,the mathematical model of resonant cavity piezoelectric energy harvester is established and optimizing its structural parameters by analytical method.Based on the Bernoulli equation and the continuity equation,the pressure equation in the main cavity is derived.Based on the basic principle of piezoelectric,the electromechanical coupling equation of piezoelectric cantilever beam is derived.The pressure equation and the electromechanical coupling equation are combined to derive the output voltage equation of the energy harvester.The pressure equation and the output voltage equation are analyzed by Mathematics to study the influence of the structural parameters of the piezoelectric energy harvester on the output voltage.The results show that the turbulent cylinder,the Helmholtz resonator,and the piezoelectric ceramic piece have the best parameters to optimize the piezoelectric performance of the harvester.And the structure parameters of the piezoelectric energy harvester are obtained.Next,the effects of piezoelectric cantilever beam,the gap between the substrate and the main cavity,the spoiler cylinder and the Helmholtz resonator structure parameters on the power generation performance of the piezoelectric energy harvester are studied by flow-solid-electric simulation.And the structural parameters of the harvester are obtained.Comparing and analyzing the structural parameters obtained by the simulation method and the analytical method,and then the optimized structural parameters of the harvester are obtained.Finally,The piezoelectric energy harvester experimental test platform was built and tested.Through the relationship between the wind speed and the open circuit voltage,it obtains the starting wind speed 5m/s and the cutoff speed 25m/s.By studying the influence of load resistance on the output power,the optimal external load resistance is 60k?.As the wind speed is 22m/s,the peak output voltage is 9.6V and the peak output power is 1.536 mW.