A two-dimensional electromagnetic vibration energy harvester with variable stiffness

This work investigates the performance of an electromagnetic vibration harvester for two-dimensional vibrations with variable magnetic stiffness and damping. The device consists a free-to-move cylindrical structure set bearings located on top bottom, couple coils bottom finally fixed system disk-shaped magnets placed inside ring holder. number in holder can be varied to change system. is characterized experimentally nine different configurations magnets, exploring both symmetric asymmetric designs. Using XY-shaker vibrate two dimensions frequencies from 1 Hz 10 motion amplitude 2 mm axes, maximum power 27 mW was harvested. occurs device, i.e. stiffnesses along its axis. For devices lower by factor two. Finally, varying damping, which controlled coil dimensions, further increase 42 mW.