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Magnetoelectric turbo-generators with direct drive from a turbine which rotor speed reaches several hundreds thousands rpm are widely used in microturbine power plants. Due to the action of centrifugal forces, the permanent magnets of the rotors endure considerable mechanical stresses. In most cases, brittle rare-earth permanent magnets are used in microturbines. To ensure the mechanical stress of high-speed rotors a bandage of high-strength non-magnetic materials is installed on permanent magnets with tension. This reduces the magnetic flux in the gap of the electrical machines. The paper presents the results of the development of high-speed rotors with permanent magnets using a welded combined bandage having nonmagnetic and ferromagnetic regions.

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.