Enhanced low-velocity wind energy harvesting from transverse galloping with super capacitor

Abstract

To improve the low-velocity wind energy extracting performance, a galloping piezoelectric energy harvester with an external super capacitor in addition to the small internal piezoelectric capacitor is designed. The electromechanical extension of the Hamilton's principle is adopted to establish the fluid-structure-electricity coupled distributed-parameter model with the Euler-Bernoulli beam assumption and quasi-steady hypothesis. Using the harmonic balance method, the approximate analytical solutions of the onset galloping speed, dynamic response and electric output of the nonlinear energy harvester are derived. Simulink simulations validate the nonlinear multiple solutions of the proposed model. The interface circuit is optimized via the electrical damping dependent of the external capacitance, inductance and resistance. The external super capacitor is chosen to satisfy the optimal electrical damping with the acceptable inductance for the power maximization. Wind tunnel experiments demonstrate that the harvested power is enhanced 450% by incorporating the super capacitor in the galloping system for low-velocity wind energy harvesting. The proposed energy harvester is able to be extended to meter scale or shrunk to millimeter scale for the field application needs.