Stochastic Thermodynamics of an Electromagnetic Energy Harvester

Abstract

We study the power extracted by an electromagnetic energy harvester driven by broadband vibrations. We describe the system with a linear model, featuring an underdamped stochastic differential equation for an effective mass in a harmonic potential, coupled electromechanically with the current in the circuit. We compare the characteristic curve (power vs. load resistance) obtained in experiments for several values of the vibration amplitude with the analytical results computed from the model. Then, we focus on a more refined analysis, taking into account the temporal correlations of the current signal and the fluctuations of the extracted power over finite times. We find a very good agreement between the analytical predictions and the experimental data, showing that the linear model with effective parameters can describe the real system, even at the fine level of fluctuations. Our results could be useful in the framework of stochastic thermodynamics applied to energy harvesting systems.

A Circuit Theory Perspective on the Modeling and Analysis of Vibration Energy Harvesting Systems: A Review

“…The typical energy harvester for ambient mechanical vibrations is composed of an oscillating structure, responsible for capturing vibrational kinetic energy, and a transducer that converts kinetic energy into usable electrical power. The oscillating structure can be a spring, a membrane or a cantilever beam, connected to an inertial mass to enhance the oscillation amplitude [12,[16][17][18][46][47][48][49]. Assuming that the mass of the structure is negligible with respect to the inertial mass, and that the motion occurs at least approximately in a straight line, the equation of motion for the mechanical part reads…”

Inference of Time-Reversal Asymmetry from Time Series in a Piezoelectric Energy Harvester

“…The piezoelectric energy harvester is a device featuring a cantilever structure with a tip mass, whose displacement in time x(t) induces a voltage v p (t) across the electrical load. As shown in [3,22], when driven by broadband vibrations, this system can be very well modeled as a generalized linear Langevin equation with an exponential memory kernel, taking into account the electromechanical coupling between the tip mass velocity and the voltage. Equivalently, the same system can be described by two coupled linear equations: an underdamped Langevin equation describing the dynamics of the tip mass position x(t) in a parabolic potential and a deterministic linear equation for the voltage v p (t).…”