Raymond Alan White

Novel high speed induction motor for a commercial centrifugal compressor

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 krpm motor features a unique laminated rotor with a multi-function, 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 pre-prototype 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.