Design of MW Grade Direct-Driven Permanent-Magnet Synchronous Generators for Wind Turbines

　　Design of MW Grade Direct-Driven Permanent-Magnet Synchronous Generators for Wind Turbines
　　Without the typical gearbox in wind-generating system and the disadvantages caused by gearbox, the PMSG (permanent magnetic Synchronous generator) is directly driven by the wind turbine at low speed, which makes the operation of the generator more liable. PMSG is different with salient pole Synchronous generator and its poles are made of the rare earth material with Neodymium Magnets high BH product, which avoids the excitation losses, makes the generator structure simpler with high efficiency.Direct-driven PMSG works at low speed and its size is generally big. In this paper, the inner-rotor structure is selected for the convenient transportation and good cooling. Firstly the design goal is proposed and it is to improve the generator liability and lower the cost on the precondition that match with the basic generator parameter requirements. Then a program is developed http://www.999magnet.com on the theory of EMCM (equivalent magnetic circuit method) and it is used in the pre-design of the PMSG. Thirdly generator characterizes are analyzed on different working condition with FEA (finite element analyze). Finally, the air-cooling system is designed and air rate is calculated.