Bistable vibration energy harvester and SECE circuit: exploring their mutual influence

The present work focuses on vibration energy harvesting to replace chemical batteries as power supplies in wireless autonomous sensors. More particularly, this article deals with nonlinear inertial oscillators and more precisely bistable harvesters, which offer a wide bandwidth compared to linear structures. These harvesters require AC–DC electronic interface to be able to supply wireless sensors or small intermediate storage elements (used to smooth the power demand). However, few studies have investigated the influence of AC–DC circuits on bistable harvesters. This work therefore focuses on developing the first analytical model able to predict the frequency response of a bistable harvester coupled to one of these interfaces: the SECE (synchronized electric charge extraction) circuit. This mathematical model includes subharmonic behaviors, stability analyses to small disturbances and the analyses of the stability robustness of high orbits characterizing their capability to handle external disturbances in real conditions without falling on a low orbit. The model is then validated experimentally with a buckled beam bistable harvester with piezoelectric conversion. The latter shows that the use of SECE circuit leads to multiply the mean extracted power from 1.3 to 2.2 compared to a direct connection to the load. The reachable frequency range is nevertheless divided by 1.55.