Analysis of converter topological structure for direct-drive wind power system with PMSG

Wind energy has drawn worldwide attention. Because of simple structure, high efficiency, stable operation and other inherent advantages, variable speed constant frequency (VSCF) direct-drive wind power generation system using permanent magnetic synchronous generator(PMSG) is the development trend and one of the focuses of wind power generation system, on which this paper researches through its converter´s topological. To be the interface between PMSG and the grid, typical converter topology structure of direct-driven wind power system with PMSG are analyzed, including the diode rectifier + DC to DC converter + inverter, and the back to back double PWM converter. The topological characteristics and applications of some high-voltage, high-power converters are introduced in detail, including Diode-clamped multi-level converter, Cascaded H-bridge multilevel converter and Flyingcapacitor multilevel converter. Their implementations, working principles, advantages and disadvantages are discussed and compared. Judging from the current situation, for the advantages of low-cost and simple control strategy, diodeclamped three-level PWM converter is the hot spot of current converting technique study for direct-driven wind power system.