Influence of Design Parameters on Cogging Torque in Directly Driven Permanent Magnet Synchronous Wind Generators

In order to reduce the cogging torque, this paper investigates the influence of some parameters on the cogging torque developed by directly driven permanent magnet synchronous wind generators. Based on the remanent magnetic flux densities, the cogging torque is computed by using finite element method. It is shown that many parameters have influence on cogging torque and the slot and pole number combination has a significant effect on cogging torque. A simple factor has been introduced to indicate the effect of the slot and pole number combination. Some practical experience to reduce the cogging torque was applied to 2 MW three phase permanent magnet synchronous generator at rated speed of 37.5 rpm for wind energy conversion. The simulation and experiment results verify the effect of the proposed method.

混凝土牛腿加固在工业厂房中的应用

在工业厂房的改建、扩建设计当中,由于结构使用功能的改变,经常会遇到对原有混凝土结构牛腿加固问题;在加固空间有限、业主对设计有特殊要求的情况下,利用柱侧牛腿和齿槽的联合设计方法能有效地提高原混凝土结构牛腿的抗剪设计承载力;在设计和施工构造措施的保证下,牛腿加固取得了成功,对以后同类问题的设计起到借鉴作用。