Dual-boost-NPC converter for a dual three-phase PMSG wind energy conversion system

The development of wind energy conversion systems (WECS) is currently focused in reaching higher power ratings (≈10MW). Medium voltage operation is at this power level, particularly at grid side, a desirable feature. Therefore, great attention has been given to high-power medium-voltage multilevel converters for WECS. Nevertheless, most modern multi-megawatt turbines use low-voltage multiphase permanent magnet synchronous generators (PMSG) operating at 690V, which requires the use of several converters connected in parallel to reach the multi-megawatt level. This paper presents a low- to medium-voltage converter interface for a dual three-phase PMSG based WECS. Two full bridge diode rectifiers followed by boost converters are used to control each set of three-phase windings of the dual PMSG. The boost converters elevate the voltage to feed each one of the capacitors of the dc-link of the medium voltage NPC grid-tied inverter. The generator side converter has high power density and is a cost effective solution compared to traditional back-to-back solutions. Simulation results are presented to provide a preliminary overview of the performance of the system.