Nonlinear multi-frequency converter array for energy harvesting from broadband low-frequency vibrations

This work proposes and experimentally validates a vibration energy harvester which combines the multi-frequency and nonlinear approaches into a converter array. The converter array consists of four piezoelectric cantilevers composed of ferromagnetic substrates with screen-printed lead zirconate titanate (PZT) layers coupled with a single permanent magnet spring suspended on the array base in order to create a nonlinear behavior. The presence of the moving magnet and the possibility to fabricate cantilevers with different potential curves can be useful to obtain a collective nonlinear behavior due to strong coupling irrespective of the amplitude of the mechanical excitation, therefore increasing the overall effectiveness of the converter array. The experimental results confirm that combining cantilevers with different potential curves can be useful to obtain a collective bistable behavior, therefore increasing the overall effectiveness of the converter array.