Modeling and Simulation of a Piezoelectric Stack Energy Harvester Based on Human Motion

Abstract

This paper presents modeling and simulation of a piezoelectric energy harvesting system optimized for human walking motion. Unlike conventional energy harvesters designed for high-frequency mechanical oscillations, this system is specifically tuned to operate within the low-frequency range of human gait <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(\sim 2 ~\text{Hz})$</tex>. The proposed piezoelectric materials (Lead Zirconate Titanate PZT-5H) stack within a dynamic spring-mass-damper system to efficiently convert the footstep impact forces into maximum output voltage. A mechanical amplification mechanism enhances strain on the piezoelectric material, maximizing output voltage. The generated AC voltage is rectified using a full-wave bridge rectifier and regulated through a DC-DC converter, ensuring optimal power delivery to battery for continuous energy storage. The simulation results, implemented in MATLAB/Simulink, validate the effectiveness of the proposed system, demonstrating the effectiveness of the proposed piezoelectric stack in converting mechanical stress into output voltage. The key novelty of this work lies in optimizing the resonance frequency of the piezoelectric stack PZT-5H to match human walking motion while incorporating a mechanical amplification mechanism to enhance strain and maximize power output. This research contributes to optimizing the system by a piezoelectric stack, a layered mechanical amplification structure to enhance strain distribution and voltage output.