Circuit Modeling of Mechanical Motion Rectifiers in Wave Energy Applications

Abstract

This work presents a novel circuit analogy for modeling and controlling mechanical motion rectifier (MMR)-based power take-off (PTO) systems in wave energy applications. Each component of the MMR is individually modeled, with particular emphasis on their velocity and torque constraints to derive their electrical analogies. The overall MMR circuit is synthesized using basic kinematic constraints, and a comprehensive friction model is integrated to address the limitations of existing approaches. The proposed circuit model facilitates the derivation of explicit expressions characterizing the MMR's nonlinear dynamics. A specific identification procedure is employed to determine the circuit parameters of an MMR prototype, which is subsequently validated through experimental testing. The developed electrical analogy offers a generalized modeling approach for MMR-based devices, allowing seamless adaptability to various MMR wave energy converters (WECs) and rectification mechanisms. This, along with the integrated friction model, explicit expressions for nonlinearities, and proven experimental accuracy, establishes a robust framework for developing comprehensive wave-to-wire models of different MMR-based WECs. Additionally, the inherited electrical simulation environment is particularly well suited for designing control techniques on the generation side aimed at maximizing wave energy absorption.