Parametrically excited nonlinear magnetic rolling pendulum for broadband energy harvesting

Parametrically excited energy harvesters provide a valuable alternative to directly excited ones. However, linear energy harvesters subjected to parametric excitation usually suffer from narrow bandwidths. This letter proposes a parametrically excited magnetic rolling pendulum (MRP) with intentionally introduced nonlinearity for broadband energy harvesting. The MRP exhibited a first-order parametric resonance with a broadened bandwidth as the excitation acceleration is ≥0.2 g (g = 9.8 m/s²). When excited at 0.5 g in experiment, the parametric resonance was observed in the frequency range between 1.2 $f_0$ and 4.5 $f_0$ , with $f_0$ being the natural frequency of 4 Hz. With a peak power output of 3.6 mW, the MRP achieved a half-power bandwidth of 4.8 Hz, which is 120% of its natural frequency. Simulation results suggest that the power output, the bandwidth, and the resonance frequency can be manipulated by varying the magnet dimensions and positions.