This paper is on the modulation of offshore wind energy conversion systems with full-power converter and permanent magnet synchronous generator with an AC link. The drive train considered in this paper is a three-mass model which incorporates the resistant stiffness torque, structure and tower, in the deep water, due to the moving surface elevation. This moving surface influences the current from the converters. A four-level converter is considered with control strategies based on proportional integral controllers. Although more complex, this modulation is justified for more accurate results.