Performance evaluation of a dual-piezoelectric-beam vibration energy harvester with a lever and repulsive magnets

This study proposes a novel dual-piezoelectric-beam vibration energy harvester with a lever and repulsive magnets (DPBLM-VEH) for performance improvement. The DPBLM-VEH integrates the benefits of the dual-beam configuration, the leverage effect and the magnetic nonlinear behavior. First, a theoretical model of the DPBLM-VEH is developed. It is found that the energy harvester exhibits two resonances in the low-frequency band, where the high-efficiency energy harvesting can be realized. A parametric study is then performed to understand the effects of various system parameters on the energy harvesting performance. Detailed design strategies in terms of tuning the lever length ratio, lever mass ratio, tip mass ratio and internal resistor towards system optimization have been proposed. Subsequently, an experimental study is conducted for validating the theoretical predictions. Experimental results show that compared to the conventional dual-piezoelectric-beam vibration energy harvester (DPB-VEH), introducing a lever (i.e. DPBL-VEH) can amplify the peak powers of the 1st and 2nd beams, respectively, by 225.8% and 134.1% around the second resonance. Similarly, the DPBLM-VEH with a further introduction of the magnetic nonlinearity can realize an amplification by 204.8% and 119.8% for the two beams. In addition, compared to the DPBL-VEH, the DPBLM-VEH can further broaden the effective bandwidths of the two beams by 98.0% and 50.6%, respectively. Therefore, we can conclude that due to the leverage effect and magnet-induced nonlinearity, the DPBLM-VEH can significantly enhance the energy conversion efficiency and broaden the operation bandwidth.