Shielded axially slitted solid rotor design for high-speed solid rotor induction motors

With its simple construction, excellent mechanical and thermal capabilities to withstand stress, solid rotor induction motors (SRIMs) have become widely used in the areas of high-speed and high-pressure application fields. In this study, a novel solid rotor structure with slits in axial directions, of which the top of the rotor iron teeth is coated with copper, is presented. The design of the novel construction is discussed in detail and all rotor geometrical design parameters are optimised. The performance of the novel rotor design is compared with that of equivalent axial-slit and copper-coated solid rotors. To determine the performances, the systems were simulated by two-dimensional time stepping finite-element analysis. In the novel structure, the fundamental flux can penetrate much deeper than that of a smooth-type induction motor because of the presence of slits. In addition, because of the existence of coating on the top of the teeth, the rotor creates decreased torque ripple resulting in less vibration. The novel rotor design provides a better efficiency with less rotor loss together with a disadvantage of decreased power factor.