NOVEL SYNCHRONOUS MACHINES - LINEAR AND DISK

The paper considers some of the developments that have taken place over the last few years in the field of synchronous machines of unusual geometry. The advances, in common with improvements in conventional drives, have only been possible because of developments in power electronics and materials. In the field of industrial drives, the linear induction motor with its simple variable voltage controller is established as a worthwhile product. Several manufacturers enjoy steady sales. Linear synchronous motors are a comparatively new development in this field; they have the virtue of considerably higher force production but require a variable frequency supply. However, in small sizes, power integrated circuits have become available that can be used to power the machines as brushless DC drives. A tubular version using permanent magnet excitation is described. In the area of transportation it is evident that, in the schemes under investigation, the linear synchronous motor is beginning to dominate the position. The most developed high speed systems use long-stator synchronous machines. However, short-stator versions are also under investigation, and the paper describes some recent studies. The development of disc brushless alternators is also described. In these machines the excitation winding is located on the same side of the airgap as the AC winding. A demonstration of the use of the new ‘high’-temperature superconductors, which uses a double disc form of these machines, is outlined. © 1990, The Institution of Electrical Engineers. All rights reserved.