A bistable electromagnetic energy harvester for low-frequency, low-amplitude excitation

In this work, we propose a bistable vibration energy harvester that can be used for non-resonant low-frequency, low-amplitude excitation. The design exploits magnetic bistability created between a pair of repelling magnets. Unlike base-excited beams, our design relies on placing one magnet on the tip of a cantilever beam having a fixed base, while transversely moving an opposite magnet thereby displacing the beam across its two stable positions with an amplified motion to harvest greater amounts of power by electromagnetic induction. A theoretical model is developed to simulate the dynamic behavior of the system at different excitation frequencies, amplitudes and magnetic gaps in order to assess the effect of the design parameters on the performance. It was found that the proposed design is beneficial and outperforms conventional linear oscillators for a broad range of frequencies, except at the linear resonance frequency. The results are supported experimentally over a range of load resistance.