Design and control of 2kW class power takeoff unit for rotating body type wave energy converter

The hydraulic power takeoff converter has been commonly applied to the rotating body type wave energy converters. It is because the hydraulic converter is more suited for dealing with periodic oscillating property of the body in a cost effective way. In order to extract wave energy effectively, the pressure and flow rate of the working fluid in the hydraulic converter should be kept adequately reflecting the period and height of given ocean wave. The pressure and the flow rate of the working fluid have effects on providing desired phase between incident wave and rotating body, and achieving optimum amplitude for the rotating body, respectively. To accomplish these objects together, a flexible controller is required reflecting the large variety of real ocean wave conditions. If the desired flexibility is limited, this may seriously affect the energy absorbing efficiency. The controller is designed to maintain the pressure and the flow rate of the working fluid at an optimum condition according to the given incident waves.