Analysis of electromagnetic processes in high-speed electrical machines with foil gas-dynamic bearings

Currently, one of the directions of electromechanical systems progress is the development of on the base of electric machines with ultra-high rotational speed (100000 and more rpm). The operating parts of these aggregates are turbine and/or compressor impellers, located on the same shaft (ie, without mechanical gear) with the inductor of the electric machine, so that these devices can be called "electrical turbo machines" (ETM). Such machines are the basis of prospective power stations with power from 1 to 400 kW for efficient low-pressure oil-free centrifugal compressors and blowers, vacuum pumps, refrigeration units, turbine generators and other devices. In this paper a number of specific problems of ultra-high speed ETM creation are described. Selection of the bearings type and selection of the electric machine type are provided. Influence of rectifier connection scheme on power losses in the machine is evaluated.