Electromagnetic Non-Resonant Vibration Energy Harvesters with Linear Magnetic Gear

This paper presents a non-resonant vibration energy harvester (VEH) with an external magnet array to enhance the output voltage through a linear magnetic gear (MG) effect. A magnet array with an optimal number of smaller-sized magnets is fixed above the VEH (2.5 cc and 5.5 g) and is shown to increase the relative velocity between the internal magnet array (suspended by ferrofluid bearings) and the coil array (mounted on the VEH chamber), increasing the time portion of non-zero relative velocity per cycle. The electromagnetic VEH, with a coil array of 2000 turns and 525 Ω, is measured to produce an open-circuit voltage of 26.3–61.6 mVrms over 0.8–4.0 Hz under 0.3 g acceleration.