Study on the asymmetric bistability of the vibration energy harvester based on diamagnetic levitation

To improve the output characteristics and enlarge the working bandwidth of the vibration energy harvester based diamagnetic levitation, the asymmetric bistability of the energy harvester is studied. The analysis model of the energy harvester is established in COMSOL ™ , and nonlinear vibration model of the energy harvester is established in MATLAB. Under different structural parameters and external excitations, the response of the floating magnet is obtained. The results show that the asymmetric bistable model has a wider response and lower energy barrier than symmetrical model. It is easier to achieve periodic motion with large amplitude, which is beneficial to improve the output voltage of the energy harvester. Simultaneously, three connection modes of the coils are compared, and it is found that the optimized coils connection pattern can significantly improve the output voltage of the energy harvester. Finally when the floating distance is 4.2mm, there are two stable equilibrium positions: Z+=0.86mm and Z-= −1.00mm respectively, and, the negative and positive displacements of the floating magnet are about −1.3mm and +1.25mm respectively. When the upper and lower coil layers both are one layer, the maximum output voltage of the energy harvester is about 3mV.