Abstract: A drive train comprising an electric machine including a rotor and a stator, the stator being connected to an alternating grid and having a stator frequency, and a bidirectional system for converting an alternating current into another alternating current. The conversion system is connected between the grid and the rotor, and comprises an AC-DC converter connected to the grid, an inverter connected between the AC-DC converter and the rotor, and a device for controlling switches of the inverter according to a control law. The control law is such that the active power exchanged by the inverter with the rotor is essentially always lower than 0.3 times the nominal power of the direct current specifically circulating between the AC-DC converter and the inverter, for the frequencies of a target interval of between 0.6 times the stator frequency and 1.4 times the stator frequency.

Abstract: The present invention provides an improved architecture for integrating an inertial navigation system (INS) into a dynamic positioning (DP) system for a vessel. The architecture includes an INS unit and a DP system having a Kalman filter or other algorithm for combining data supplied by a plurality of position measuring equipment (PME) and the INS unit to derive an estimate of the position or speed of the vessel. A switch array and a switch array controller are also provided. These may optionally form a part of the DP system. The switch array is operable under the control of the switch array controller to supply data supplied by one or more of the plurality of position measuring equipment to the INS unit for the purposes of correcting drift. The selection of which of the one or more PME is/are to be combined with the INS unit is made automatically, in real time, to dynamically optimise the DP system.

Abstract: In an oscillating water column (OWC) assembly power may be generated based on a power reference that is derived from an estimate of the available mechanical power in the air turbine 2 or a measured pressure drop across the turbine. The power reference is used to derive a power control torque reference within a power controller 14. A speed controller 16 uses a comparison of a measured speed of the generator 8 and a maximum speed limit to derive a speed control torque reference. A selector function 22 selects whichever of the power control and speed control torque references is the maximum at any time instant. The selected torque reference is input to an anti stall torque function 24 where it is selectively modified by applying a speed dependent gain that decreases with decreasing turbine speed, preferably so that the main torque reference is zero for a minimum speed limit.