A bistable vibration energy harvester with spherical moving magnets: Theoretical modeling and experimental validation

In recent years, battery-free self-powered sensing has attracted much attention. However, effective energy harvesting over wide frequency bandwidth is still a great challenge. This paper explores a bistable vibration energy harvester. The harvester uses a spherical magnet as a moving magnet, combining the restoring force of limit spring, attractive magnetic force and gravity to achieve bistability to increase power output and bandwidth. A prototype of the harvester is constructed and characterized experimentally. The nonlinear dynamic model of the harvester is formulated and validated using the experimental data. The impedance matching experiment is carried out at a fixed frequency. The working frequency range is 12–43 Hz at 4.5 g. The maximum peak to peak output voltage is 18.9 V. At 40 Hz and with a 900 Ω load, the output power reaches 11.5 mW.