Frequency tunable electromagnetic vibration energy harvester based on diamagnetic levitation

In order to solve the defect that the intrinsic frequency omega 0 of the diamagnetic levitation electromagnetic vibration energy harvester cannot be adjusted, a pulling magnet with downward attraction to the floating magnet is added below the floating magnet of the original structure. The simulation found multiple omega 0 exist in the structure with the pulling magnet, and the relationship between omega 0 and the vertical distance LL from the lifting magnet's lower surface to the floating magnet's upper surface is determined. It is found that omega 0 can be varied from 2.36 to 12.3 Hz by adjusting LL. The dynamic characteristics of the floating magnet is studied to obtain its amplitude-frequency curve. The output performance of the energy harvester at different omega 0 is calculated and the simulation results are well verified experimentally. The experiments show that the effective voltages can all reach their maximum after arranging the induction coil when the excitation frequency is from 2.2 to 6.1 Hz. The frequency band width for effective voltages greater than 400 mV is made up to 7.6 Hz. The maximum effective voltage of the structure with the pulling magnet is 749 mV, which is 1.98 times larger than the structure without a pulling magnet; the maximum power is 779 mu W, which is 7.9 times larger than the structure without a pulling magnet. Experiments show that the structure with the pulling magnet not only significantly broadens the effective bandwidth of the energy harvester, but also significantly improves the output performance of the energy harvester. In addition, the nonlinear characteristics of the system make it possible to obtain good output performance even when the vibration frequency is far from omega 0.