Optimisation of Electromechanical Drivetrain for Wave Energy Converter at CorPower Ocean AB

Abstract: The potential of wave energy has been constantly explored in past couple of years. The contribution from the CorPower Ocean AB towards the development of wave energy is important. This thesis involves the detailed study of current ½ scale (1:2) model of a Wave Energy converter (WEC) and computing the results to find the optimised component ratings. The primary goal of the thesis is to optimise each component of the electro-mechanical drivetrain with the assistance of modelling software Simulink and Matlab. In the initial stage of this thesis the generator and drive component are analysed without changing the drivetrain configuration of the WEC. A method is established to find suitable ratings of generator and drive system for the WEC which provides high system efficiency and power output. The method is developed in such a way that it can be implemented for any scale model whether it is full-scale or half-scale. Once finding the optimised ratings of generator and drive combination, different configuration of the drivetrain is explored for the WEC. The influence of drivetrain mechanism with and without flywheel is also considered and compared with the ½ scale model. The drivetrain configurations comprise of single generator, double generator and quadruple generator alignment with the WEC.  All configurations of the generator are compared with and without a flywheel in the drivetrain. The benefit of including a flywheel involves power smoothing, control simplification and reducing component volume, whereas the benefit of not including flywheel includes better hydrodynamic damping and control. The outcome of the results showcase that the existing ½ scale WEC model can provide better performance when the generator ratings are reduced because of low speed at small sea state. The speed-ratio of the gearbox can either be increased or a new system can be introduced which chooses the generator rating depending on the sea state and motion profile. Based on the analysis result of an optimised ½ scale model, the full scale drivetrain component ratings are introduced with a different drivetrain topology. Results from the Full scale WEC model showcase that a double generator WEC configuration without a flywheel is a reliable and efficient solution for CorPower Ocean AB.