Ultra-low frequency and small-amplitude electromagnetic vibration energy harvester considering rotary multi-magnetic-electrical-mechanical coupling

The linear-to-rotary electromagnetic vibration energy harvester has garnered significant attention, especially in the context of small-amplitude, ultra-low frequency vibrations. However, the conventional mechanical structures feature unavoidable meshing gaps and substantial contact friction, thereby impacting transmission efficiency and energy harvesting performance. Therefore, this work presents a linear-to-rotary electromagnetic vibration energy harvester (REM-VEH) with magnetic lead screw (MLS) designed to mitigate performance degradation resulting from backlash and nonlinear friction and achieve speed amplification. Moreover, to examine the influence of multi-field coupling on the harvesting performance in the absence of a precise nonlinear rotational coupling model, a coupled dynamic model incorporating multi-magnetic, electrical, and mechanical couplings is developed. An experimental prototype is built and examined, confirming the validity of the coupled dynamic model. The findings indicate that an average output power of 32.90 mW is attainable at an excitation frequency of 3 Hz and an amplitude of 0.4 mm, with a matching resistance of 30 Omega. This paper introduces an innovative implementation strategy for achieving vibration amplification and enhancing energy harvesting performance under conditions of low frequencies and small amplitudes.