Induction motor with spiral sheet rotor

Improvements in torque at low currents using a rotor with spiral sheets are analyzed. Several rotors and stators have been built combining different constructive and mechanical characteristics of the related elements: inertias, constructive materials, geometrical shapes of the sheets and geometrical disposition of the sheets. These different types of motors have been simulated using computer aided tools and then tested in the laboratory. Finally, four stators (1000, 1500, 1500-type A, and 3000 rpm) with the same constructive parameters, have been simulated and tested with the following rotors types: solid rotor, solid rotor with diamagnetic rings, drag cup, and simple and double squirrel cage rotor; the results have been compared to those obtained with the seven variants of spiral sheet rotor presented in this paper.