Analysis of influence of nonlinearities and noise correlation time in a single-DOF energy-harvesting system via power balance description

We discuss the role played by the time correlation properties of stochastic sources and by model nonlinearities in single-degree of freedom energy harvesting systems. After transforming the state equations into energy-angle coordinates, we apply a stochastic projection operator technique to obtain the system power balance equation. The latter allows to evaluate both the magnitude of the power injected by noise into the system and the harvested power, thus providing a tool instrumental for designers to optimize the harvester. We show that for systems with modulated (multiplicative) noise, nonlinear energy harvesters can outperform their linear counterparts, highlighting the physical mechanism that explains their better performance.