A cascaded two-port network model for the analysis of harmonic chain-based energy harvesters

This paper analyzes a recently proposed energy harvester model, based on a harmonic chain of coupled oscillators connected to a piezoelectric transducer. We discuss first how random mechanical vibrations can be modelled as a superposition of sinusoidal signals with random amplitude and phase. Using a mechanical-electrical analogy, we derive equivalent circuits in the form of two-port networks, for both the single mass and the N-mass energy harvester. The transfer functions for both the single mass and the N-mass (valid for any number of masses in the harmonic chain) devices are then obtained cascading the two-port representations of the individual sections, and we give expressions for computing the output power and the power efficiency. Pros and cons of the harmonic chain model are also briefly discussed.