1 Abstract— Ocean currents contain potentially abundant source of energy that can be captured and converted to a usable form. In this paper the dynamics of a small marine current energy conversion system has been modeled and simulated. This proposed power generation system consists of a next generation horizontal axis turbine, a low rpm generator, a controlled DC-DC converter and batteries for energy storage. The next generation rotor has blades facing forward into the flow and ensures high starting torque even in low currents as the blade is not perpendicular to the flow direction. The control strategy is aimed at following the water turbine’s maximal power coefficient by adjusting the duty cycle of the DC/DC converter. Simulation results exhibits that the proposed system can continuously harness a significant amount of power from the sea current and can be an attractive source of power for small isolated loads. Keywords—Permanent magnet generator, maximum peak power tracking, sliding mode, dc/dc converter. I. INTRODUCTION Power generation in harsh seafloor conditions is the major challenge. Batteries cannot store power for a long time. Closed cycle engines need storage of fuel and oxygen for a long time that is not possible in seafloor conditions. Light often does not reach that area, therefore photovoltaic are not an option. Temperature differential is nominal therefore; ocean thermal energy cannot be exploited. Only remaining options are wire linked floating wave energy converter and ocean current converter. A fundamental requirement for the success of the power system is the presence of ocean currents of sufficient velocity near the seafloor to permit self-contained energy generation [1,2]. This paper deals with the development of a Matlab model of a marine current turbine system through the modeling of a suitable rotor. The simulation model has two purposes: performance and dynamic responses at different operating conditions and robust control system development for turbine operation based on optimum speed control. Maximum power algorithm based control scheme will ensure that the system is always extracting the maximum power from the water current[3]. It should be noted that when scanning the literature, one will find very few papers on this topic. II. MARINE CURRENT ENERGY Energy conversion from marine currents is quite similar to that of wind energy conversion but there are also several differences between them. The underwater placement of a marine current energy converter (MCEC) gives some advantage such as no noise disturbance for the public, low visual exposure and little use of land space but also adds some challenges like the need for water and salt proof technology, difficult and costly maintenance etc. Ocean current speeds are generally lower than wind speeds. This is important because the kinetic energy contained in flowing bodies is proportional to the cube of their velocity. However, another more important factor in the power available for extraction from a flowing body is proportional to the density of the material [4]. Thus, ocean currents represent a potentially significant, currently untapped, reservoir of energy. The total worldwide power in ocean currents has been estimated to be about 5,000 GW, with power densities of up to 15 kW/m 2 . Ocean-current generated energy technologies have many favourable characteristics, including the following: Water currents have a relatively high energy density. Some ocean currents are relatively constant in location and velocity, leading to a large capacity factor (fraction of time a system is actively generating power) for the turbines. Because they are installed beneath the water’s surface, water turbines have minimal visual impact. A high utilization factor is important to achieve an economically viable power production. A drawback with marine currents as an energy source is that the water currents usually have a low velocity that rarely exceed 5m/s . Lower current velocities results in low turbine speeds, thus, if a conventional generator were used to produce electricity, a gearbox becomes essential to achieve higher rotor speeds. It is important to note that gearboxes contribute to mechanical losses and require maintenance regularly to avoid power generation failures. Nahidul Khan, Michael Hinchey, Sheikh Rabbi, Vlastimil Masek, Tariq Iqbal DYNAMIC MODELING, SIMULATION AND CONTROL OF A SMALL MARINE CURRENT ENERGY CONVERSION SYSTEM