I. Introduction
Vibration energy harvesters [1]–[7] are widely used in order to feed Wireless Sensor Nodes (WSNs) [8]–[9]. This paper is focused in particular on Resonant Electromagnetic Vibration Energy Harvesters (REVEHs) [5]–[7]. In Fig. 1, a typical REVEH system is shown. The REVEH has been represented by means of its equivalent electric circuit [8]. is the coil inductance, is the coil resistance, is the base acceleration with an angular frequency . The values of and are: , is the viscous damping coefficient, Θ is the electromechanical coupling coefficient, is the stiffness coefficient, m is the vibrating mass).
REVEH system.