Design And Research Of A Type Of Piezoelectric Vibration Energy Harvester With Rotary Movement

The piezoelectric vibration energy harvester has the characteristics of small volume,high integration degree,and high electro-mechanical coupling effect and energy density,so it is often used in the self-power supply of low power wireless electronic equipment.In practical applications,the frequency of vibration source not only shows the characteristics of wide frequency,but also the direction is random.The piezoelectric energy acquisition technology based on linear vibration,unidirectional or finite direction has limitations in many applications.Therefore,this paper designs a servo rotary piezoelectric vibration energy harvester and analyzes its energy acquisition characteristics.The main work is as follows:(1)By using Euler-Bernoulli beam theory and magnetic dipole model,magnetic potential energy,kinetic energy and external work of each part of the system were obtained.A distributed parameter model of the magnetically coupled piezoelectric cantilever beam vibration energy harvester was established.The dynamics equation was dimensionless and the state-space equation was obtained.Based on the method of multiple scales,the system stability of the energy harvester is analyzed,and the influence of the distance between magnets and the excitation amplitude on the resonance characteristics of the system is studied.(2)The structure of a rotating piezoelectric vibration energy harvester is designed,which can adjust the vibration direction of the piezoelectric plate according to the maximum vibration acceleration,so as to expand the energy conversion performance of the energy harvester.A method of multiple scales was used to analyze the frequency domain of a servo rotary piezoelectric vibration energy harvester.The resonance characteristics of the combined resonance of the system,such as the distance between magnets,the excitation amplitude,the length and thickness of the cantilever beam and piezoelectric plate,and the length of the pendulum,were studied.(3)Runge-Kutta method was used for numerical solution,and the time-domain response,phase diagram and spectrum of the energy harvester were obtained under different parameters,which corresponded to the solution in the frequency domain.The system showed periodic motion,quasi-periodic motion and chaotic motion,which further verified the inf luence of parameters on the resonance vibration characteristics of different combinations.The above research shows that the magnetic coupling structure can increase the energy acquisition frequency of the piezoelectric energy harvester,and the introduction of a pendulum can enable the system to adjust the cantilever beam according to the direction of excitation acceleration,so as to obtain a larger vibration energy.At the same time,under the combined action of swing frequency and excitation frequency,the system can efficiently output electric energy in a wider band.