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Abstract

The invention provides optimal control of a three-degree-of-freedom wave energy converter using a pseudo-spectral control method. The three modes are the heave, pitch and surge. A dynamic model is characterized by a coupling between the pitch and surge modes, while the heave is decoupled. The heave, however, excites the pitch motion through nonlinear parametric excitation in the pitch mode. The invention can use a Fourier series as basis functions to approximate the states and the control. For the parametric excited case, a sequential quadratic programming approach can be implemented to numerically solve for the optimal control. The numerical results show that the harvested energy from three modes is greater than three times the harvested energy from the heave mode alone. Moreover, the harvested energy using a control that accounts for the parametric excitation is significantly higher than the energy harvested when neglecting this nonlinear parametric excitation term.

Patent Number

10,344,736

Assignee

National Technology & Engineering Solution of Sandia, LLC; National Technology & Engineering Solution of Sandia, LLC (Albuquerque, NC) Michigan Technological University

Application Number

15/837,853

Date Filed

12-11-2017

Certificate of Correction

No

Issue Date

7-9-2019

City

Albuquerque, NC; Houghton, MI

Disciplines

Engineering Mechanics | Mechanical Engineering

Pseudo-spectral method to control three-degree-of-freedom wave energy converters

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