Comparison of 5 different squirrel cage rotor designs for large high speed induction motors

Increase in efficiency, reliability, lifetime and related cost are key subjects when selecting a direct drive high speed electric motor compared to more conventional solutions. This paper disserts about how choosing the best rotor design for high speed and high voltage inductions motors for applications from 6000rpm to 18000rpm and 20MW to 4MW. High speed induction motors that we are going to refer to in this paper were firstly conceived on the 80s as an integrated set (induction motor + compressor) to be used in gas transportation, in particular for pipelines stations. The rotor is done with a laminated magnetic core and a squirrel cage. In 2012, after having manufactured more than 80 Motors, it was decided to challenge again the design of the laminated rotor and to compare it with various designs of solid rotors. Complete electromagnetic, mechanical and reliability studies were completed for , manufacturing 5 rotors designs which will be presented, analyzed and compared in this paper. The pros and cons of each design are presented in a comparative table. Extensive testing was performed on the laminated rotor and the results of this test are analyzed. The reliability in operation and, behavior of the rotor and its squirrel cage are presented.