Large Frequency Range Electrodynamic Harvester Based on Frequency-Up Resonant Converter for Rotational Movements

The aim of this paper is to investigate experimentally the feasibility and power performance of a contactless rotational energy harvesting system, designed to operate across a wide range of rotational frequencies, from a few tens of RPM to several hundred RPM, commonly encountered in various industrial environments. The harvester, based on a repurposed commercialized batteryless switch, consists of a driving magnet attached to the rotating component and a generator comprising a diametrically-magnetized magnet, ferromagnetic elements, and a coil. In this paper, we present numerical simulations to determine optimal operating conditions and resisting torques acting on the driving magnet. Then, experiments demonstrate a two-state behavior: a frequency-up effect at low frequencies and a more unpredictable, yet powerful, response at higher frequencies $(\gt7 \mathrm{~Hz})$. The harvester produces 3.5 mW at 3 Hz and up to 17.9 mW at 20 Hz for a Tx-Rx distance of $D_{x}=7 \mathrm{~mm}$. The maximum harvested power under optimal load is 28.5 mW at 20 Hz for $D_{x}=$ 2 mm. Power outputs range from $1.3 \mathrm{~mW}(3 \mathrm{~Hz})$ to $9.4 \mathrm{~mW}(20 \mathrm{~Hz})$ at $D_{x}=7 \mathrm{~mm}$ using a rectifier and capacitor circuit. Future work will consist in working on both analytical and finite element modeling to further optimize the system for enhanced performance.