This paper describes the electrical, mechanical and metallurgical design, construction, and testing of a novel low-cost high-speed high-efficiency induction motor to drive a new type of small centrifugal compressor in industrial cooling applications. The 28-shaft-hp 50-kr/min motor features a unique laminated rotor with a multifunction high-strength copper-alloy cage brazed with a novel process. Relatively thin high-silicon steel laminations were used to achieve low losses and high mechanical strength at low cost, Different heat treatments for the stator and rotor laminations were used to optimize the mechanical and magnetic properties, The preprototype motors achieved about 94% (electromagnetic) efficiency at the rated point, including inverter harmonics, while meeting cost (less than one-tenth of aerospace practice) and produceability goals.
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