Parametrically excited nonlinear magnetic rolling pendulum for broadband energy harvesting

Abstract

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 1.2𝑓0 and 4.5𝑓0 with 𝑓0 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 to by varying the magnet dimensions and positions.