Optimal Design of High-speed Solid Rotor Cage Induction Motors Considering Ferromagnetic Materials Behavior and Manufacturing Process

Abstract

Numerous high-performance industries (i.e., natural gas compression) require high-speed motors. Solid-rotor cage induction motors (SRCIMs) are perfect nominees to such applications, owing to their high reliability and relatively low cost among their rivals. However, the restrictions over ferromagnetic materials and manufacturing processes overwhelm the SRCIM's design process. The motor is required to have low power losses in stator core and the solid rotor. Furthermore, a small number of rotor slots are demanded industrially in order to facilitate the welding process in rotor's side. Those two objectives are contradicting in the design stage. This study investigates the loss characteristics of high-speed SRCIM, considering the behavior of different ferromagnetic materials and the complexity of the welding process of solid rotors. With 160-kW and 3000-kW SRCIMs, the influences of slot combination, air-gap length, stator ferromagnetic material, and rotor conductivity on the power loss characteristics are comprehensively analyzed. Based on the aforementioned analysis, an optimal design criterion for SRCIM is proposed to decline the eddy current losses in the solid rotor and to decrease the complexity of the welding process. To verify this criterion, a 160-kW SRCIM prototype is designed and manufactured. Experimental validation is performed, and the effectiveness of the proposed design procedure is verified.