Broad spectrum and wide amplitude range vibration energy harvester: bistable piezoelectric transduction, synchronized extraction, self-actuated adaptation

Abstract

The invention relates to a bistable piezoelectric cantilever-based vibration energy harvester that increases the energy harvested over a broad frequency of vibrations by introducing bistability to the cantilever through use of two repelling magnets, one mounted on the cantilever and one at a location facing the first. This increases the amplitude and velocity of cantilever vibration, hence harvested power, while nonlinearity makes the system efficient over almost the entire range of frequencies, lower than the natural resonant frequency of the linear version without the magnets. Such improved performance is seen while the cantilever remains in the bistable mode. To broaden the range of vibration amplitudes over which the harvester continues to operate in bistable mode, the harvester includes a mechanical way of tuning the magnetic force, by spring-loading the magnet facing the mounted one, enabling self-adjustment of the distance between the magnets automatically that favors bistable operation over a larger range of excitations, and that too without needing any extra energy.