Design, modeling and experimental investigation of a magnetically modulated rotational energy harvester for low frequency and irregular vibration

Vibration energy harvesting is a promising approach for sustainable energy generation from ambience to meet the development of self-powered systems. Here, we propose a novel compact non-resonant magnetically modulated rotational energy harvester (MMR-EH) for low frequency and irregular vibration. Through the rational arrangement of multiple magnetic fields in space, a ring route with low potential energy is established. A movable magnet can be non-contact modulated by the magnetic force to move along the ring route under irregular vibration, which is instrumental in electromechanical energy conversion. A dynamic model of the MMR-EH is developed based on the energy method and verified experimentally. The effects of key parameters on the magnetically modulated route are analysed. The simulation and experimental results demonstrate that the MMR-EH can effectively harvest the energy from ultra-low frequency (3 Hz) and irregular vibration. At a reciprocating vibration frequency of 10 Hz and an amplitude of 20 mm, the harvester can produce an average power of 0.29 mW.