双定子直驱无刷双馈风力发电机设计原则与反电势分析

Design Principle and Back EMF Anslysis of Direct-drive Dual-stator Brushless Doubly-fed Generator

无刷双馈电机具有固有极数高、无刷可靠、变流器功率小的优点,而且可实现变速恒频发电,特别适合大型直驱风力发电系统。针对直驱风力发电机的大径长比,转子内腔空间不能被充分利用,导致电机功率密度低的问题,本文提出了一种具有双定子结构的无刷双馈风力发电机。首先设计了一台3 MW,25 r/min的单定子无刷双馈发电机,并在此电机的转子内腔中增加了一个定子,形成双定子的电机结构。通过改变槽数、绕组匝数、槽宽等进行了多方案对比,最终确定电机的相关参数,并利用有限元法,分析了电机的空载反电势波形。结果表明,所设计的双定子直驱无刷双馈风力发电机具有良好的空载特性。

Brushless doubly fed generator （BDFG） is suitable for large variable speed constantfrequency （VSCF） wind power generation system which has the advantages such as the more naturalpoles, brushless, and smaller power of the converter. But the power density of the generator is nothigh because of the large ratio of diameter to length, which hinders its application in the field ofwind power generation. Aiming at the inherent advantages of the brushless doubly fed machine andthe existing problems, a double stator brushless doubly-fed generator （DSBDFG） is put forward tomake full use of the cavity of the inner rotor. Firstly, a 3MW, 25r/min single stator BDFG （SSBDFG）has been designed using fractional slot winding structure. Secondly, a DSBDFG has been ensured toadd a stator in the inner cavity of the rotor based on the SSBDFG through comparison of differentslot number, winding turn number and slot width. Finally, the parameters of DSBDFG aredetermined, and the no-load characteristics are simulated and analyzed by finite element method.The results show that the designed DSBDFG has good no-load characteristics.