Research on frequency bandwidth and phase difference of piezoelectric resonant cantilever based on mass

The quality of collected electric power is directly affected by the mechanical properties of piezoelectric cantilever, which is an important part of vibration energy collection system. A piezoelectric energy harvester is employed to study the electromechanical conversion performance of piezoelectric cantilever under different counterweights by adding mass blocks. An experimental platform is built to test the piezoelectric energy harvester based on numerical analysis. The effects of different mass attached to the cantilever on frequency bandwidth and phase angle difference are studied. The numerical analysis indicates that the output voltage of the two piezoelectric bimorphs in series is higher than that of the single piezoelectric plate, and the natural frequency of the structure changes little. The mass is the main factor affecting the resonant frequency and output voltage of the energy harvester based on the expression of natural frequency. The experimental results show that the maximum output voltage increases by 39.42% and the natural frequency decreases by 13.83% when the mass ratio is 11.75%, which is consistent with the numerical results. The increasing of counterweight causes the decrease of third-order natural frequency of piezoelectric cantilever and the increase of frequency bandwidth. It is demonstrated that the phase difference decreases rapidly and finally approaches to − 180° when the external excitation frequency is near the resonant frequency. The phase difference at the peak is close to zero when the mass ratio is 11.75%, corresponding to the highest voltage output. The results have reference significance for the system adaptive tuning of vibration energy harvester.