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Downloree foil bearings, 4-pole composite wound permanent magnet otor, thermal management capabilities and a state of the art entrifugal compressor. NTRODUCTION As power-density and efficiency demands for oil-free air ompressors increase, centrifugal machines with high perating speeds and direct electric drives become ncreasingly appealing as replacements for existing echnologies. The direct drive machines offer higher fficiencies, are generally smaller and quieter, and require less aintenance when using oil-free compliant foil bearings. The uccessful implementation of an oil-free, motor driven entrifugal compressor relies essentially on the availability of ive major elements: (1) an efficient, high-speed motor; (2) he necessary complimentary power electronics; (3) state-of