Control Strategies for Point Absorbers Considering Linear Generator Copper Losses and Maximum Excursion Constraints

Among the different available wave energy extraction technologies, point absorber converters that use a linear direct-drive generator represent a promising alternative. Evidence of this can be found in the different prototypes that have been widely tested in recent years. As in other technologies, the control strategy that governs the power take-off system largely determines the overall-efficiency and the dynamic behavior of the oscillating system. It is advisable to consider the copper losses in the electric generator when assessing the overall performance of each strategy, as they could significantly affect the overall efficiency of the system. On the other hand, it is expedient to manage properly the energy dissipated in the end-stops that limit the maximum displacement of the oscillating system in high waves. This paper presents two reactive and latching control strategies whose novelty is to consider simultaneously the copper losses reduction in the electric generator and the limitation of the maximum excursion constraints of the oscillating system in order to extract more energy from waves. In addition, these control strategies are compared with conventional techniques. The results of the numerical simulations allow researchers to analyze the performance of the strategies from different perspectives.