Phase control strategy for a wave energy hyperbaric converter

Oscillating bodies represent an important class of wave energy converters (WECs). In these systems, the steps of converting wave energy into electricity usually employ a floating body that is either connected to a hydraulic system and a turbine (or motor) coupled to an electric generator or connected directly to a linear electric generator. The improvement of the efficiency of the extracted energy from these systems is closely related to different control strategies. Currently, the reactive control and the phase control by latching are the most analyzed control strategies used for this purpose. This paper proposes a strategy based on phase control concepts for a hyperbaric wave energy converter-a WEC with an oscillating body linked to a hyperbaric chamber through a lever arm. A proportional-proportional integral (P-PI) cascade controller is adopted to regulate the position of a sliding mass, which is used to change the inertia of the floating body. The analysis of the body motion in regular waves is also presented. Simulation results that consider both the regular and irregular waves illustrate the performance of the proposed control scheme. (C) 2010 Elsevier Ltd. All rights reserved.