The Development of an Indexing Method for the Comparison of Unbalanced Magnetic Pull in Electrical Machines

© 1972-2012 IEEE. Unbalanced magnetic pull in cylindrical electrical machines has been studied by several authors but it can be hard to quantify and measure. This paper reviews some of the work related to UMP calculation and measurement and develops the concept of a UMP index in order to allow comparative studies. This is because the UMP can vary greatly in terms of magnitude depending on the type and topology of the machine and also the loading. Methods for measurement of UMP are also discussed and results put forward from a UMP measurement rig

High-speed synchronous generators. A critical assessment

Considering that there are electromagnetic, mechanical and thermal constraints that determine the design of high-speed electrical machines, the criteria that lead to adequate selection of the machine are established in this work. Moreover, taking into account the current state of technology, the critical values in the ratio (output power)/(rotation speed), are presented. The paper focuses on the high-speed synchronous generators, especially in permanent magnet generators, inductor alternators and flux switching alternators, emphasizing their constructive fundamentals and their advantages and disadvantages. The analysis is completed with a critical assessment that classifies them according to previously defined requirements. Although the decision of the final choice is largely determined by the application of interest, it can be said that, in general, synchronous generators with permanent magnets in the rotor are the best option.Postprint (published version