双定子笼障转子无刷双馈发电机冷却空气流变特性数值分析

Numerical Analysis of Cooling Air Flow Characteristic for Double Stator Cage-Barrier Rotor Brushless Doubly-Fed Generator

双定子笼障转子无刷双馈发电机(DSCBR-BDFG)采用了背靠背笼障转子以及双定子结构,因此其具有磁场耦合能力强、功率密度高、容错性能好等优势。针对该发电机结构复杂、散热困难、额定运行时局部温升较高的问题,研究通风结构内部冷却空气的流变特性对发电机冷却系统优化设计具有重要意义。以一台50kWDSCBR-BDFG样机为研究对象,阐述了该发电机的机械结构、绕组联结方式以及励磁控制系统,分别建立内外流体区域的三维物理模型和数学模型,给出边界条件和基本假设,根据流体力学理论,采用有限体积法对其湍流控制方程进行数值求解,得到了发电机内部空间不同位置的空气流速、流量以及迹线等空间分布特点,并对其进行详细分析。通过研究揭示了DSCBR-BDFG内部冷却介质流变特性的分布规律,为后续对该发电机通风冷却结构的优化设计提供依据。

Double stator cage-barrier rotor brushless doubly-fed generator(DSCBR-BDFG)has unique advantages of strong magnetic coupling ability,high power density and good fault-tolerant performance because of using back-to-back cage-barrier rotor and double stator structure.The local temperature rise of this type of generator is higher at the rated operation due to poor heat dissipation and complicated structure.Therefore,it is significant to research the cooling air flow characteristics in the ventilating structure for cooling system optimization design.The mechanical structure,winding connection mode and excitation control system of a 50 kW DSCBR-BDFG prototype are expatiated.3-D physical model including the internal and external fluid regions and mathematical model are established respectively.Then a few basic assumptions and boundary conditions are given and the turbulence control equations are solved numerically by finite volume method based on the fluid mechanics theory.The spatial distribution characteristics about the air velocity,fluid flow and path line are analyzed in detail.The research shows the distribution rules of internal cooling medium rheological properties of DSCBR-BDFG.It provides the basis to optimize the ventilated cooling structure subsequently.