Resonance provocation of improved energy orbit in bi-stable vibration energy harvesters for power enhancement

Bi-stable vibration energy harvesters are advantageous for a wide bandwidth in low frequency ranges, but are confronted with the issue of limited output power. Bi-stability traditionally contains two low- and high-energy orbits; however, this paper reports resonance provocation of the improved energy orbit, which is much higher than the traditional two energy orbits and can be utilized for power enhancement. Theoretically, the enhanced energy orbit is provoked due to an increase in the system’s kinetic energy, achieved by modifying the bi-stable potential energy function from quartic function to quadratic function to utilize the linear resonant restoring force. Experimental results demonstrate that the provocation of the improved energy orbit is frequency selective, and the root mean square voltage is increased by 63.6% in the upward sweep and 188.5% in the downward sweep. For optimal load, the improved energy orbit increases the maximal root mean square voltage by 2.10 times and the maximal average output power by 4.37 times. Meanwhile, the device’s bi-stable bandwidth remains almost unchanged. These results prove that the resonance provocation of the improved energy orbit can refine the power while not sacrificing bandwidth, which is a promising solution to the overall performance improvement for vibration energy harvesters.