A Dual-reed-coupled Piezoelectric Energy Harvester Using Transverse Vibrations Induced By Longitudinal Excitation

In view of the problems such as low reliability,poor environmental adaptability,unadjustable the natural frequency and unsuitable for low or even ultra-low frequency environments exist in vibration piezoelectric energy harvesters,a dual-reed-coupled piezoelectric energy harvester using transverse vibrations induced by longitudinal excitation is proposed in this paper.The magnetic coupling between the exciting magnet at the longitudinal reed end of the coupler and the excited magnet at the transverse reed end of the combined transducer is used to realize the vibration direction conversion between the two reeds.The piezoelectric oscillator on both sides of the transverse reed is forced to produce transverse bending deformation,and then the longitudinal vibration energy in the environment is converted into the electrical energy.In this paper,theoretical modeling simulation and experimental testing are studied,and the main researches include:1.The piezoelectric oscillator,combined transducer and the dual-reed-coupled piezoelectric energy harvester using transverse vibrations induced by longitudinal excitation finite element model are established and simulated by COMSOL software.The influence of the piezoelectric oscillator structure parameters(length ratio and thickness ratio)on its static characteristics and output characteristics(the output voltage and power),and the combination transducer structure parameters(clamping ratio and the thickness of transverse reed)on its static characteristics are studied.2.A two-degree-of-freedom system dynamics model of the dual-reed-coupled piezoelectric energy harvester using transverse vibrations induced by longitudinal excitation was established and simulated.The influence of structural parameters of the coupler(longitudinal reed length and longitudinal added mass)and the combined transducer(clamping ratio,transverse reed length and added mass of transverse)on the dynamic response characteristics of the harvester are studied.The results show that there are two resonant frequencies make the amplitude amplification ratio peak.Two resonant frequencies peak can be adjusted by adjusting the structural parameters of the coupler and the combined transducer.There are optimal structural parameters which can make the harvester obtain a large amplitude amplification ratio and a wide frequency band at the same time.The closer the two natural frequencies are to the amplitude amplification ratio,the larger the amplitude and the narrower the corresponding bandwidth are.3.In order to verify the correctness of the theoretical simulation results,an experimental prototype was made and tested.The influence of longitudinal reed length,distance between magnets,added mass and excitation force on the output voltage of the harvester and the influence of load resistance on the output power of the harvester with different excitation frequency and added mass are studied.The structure principle's feasibility of the dual-reed-coupled piezoelectric energy harvester using transverse vibrations induced by longitudinal excitation is proved by tests.The experimental results show that the amplitude-frequency characteristics of the harvester are determined by the coupler and the combined transducer.When the exciting frequency is less than 20 Hz,there are two optimal frequencies to maximize the output voltage,the two resonant frequencies are the natural frequencies of the coupler and the combined transducer,respectively,and the peak position and value of the two resonant frequencies can be adjusted by adjusting the above parameters.When the load resistance is 540 k?,the maximum output power is 0.2 mW.