I. Introduction
The increasing diffusion of vibration energy harvesting systems in wireless sensor networks and IoT applications has recently steered many research efforts to improve the performance of these low-power supplies [1]–[3]. The power electronic interface between the energy harvester, which is an AC source, and the DC load plays a key role in the maximization of the delivered power. Indeed, the power extracted from the harvester depends not only on the mechanical characteristics of the vibration, but also on the electronic interface directly connected to the output terminals of the energy harvester [4].