Design and analysis of power electronic converter to harvest ocean-current energy

Abstract

An ocean current is a continuous, directed movement of ocean water generated by the forces acting upon this mean flow, such as breaking waves, wind, Cariole’s force, temperature and salinity differences and tides caused by the gravitational pull of the Moon and the Sun. Depth contours, shoreline configurations and interaction with other currents influence a current's direction and strength. However, one of ocean current characteristic is varying-speed which will also vary the output of an energy converter. This project presents the comparison of two power electronic converter designs for hydrokinetic turbine system equipped with a permanent magnet synchronous generator (PMSG), to harvest ocean current energy by injecting ocean current speed data as input of overall system. An AC-DC uncontrolled rectifier is used as first stage of power conversion while two DC-DC converters (Buck-boost and SEPIC) are being compared for second stage. The proposed power conversion system model is designed to maintain constant DC output voltage with almost zero ripples for battery charging by using PI-control method. MATLAB/Simulink is used to simulate the proposed systems. The obtained result shows that the averaged output voltage is at 25.85V. With PI-control method, the output voltage maintains at small ripple.