High frequency cage rotor designs

Abstract

It is shown that two-dimensional finite-element (FE) analysis in combination with geometrical considerations and interface with a detailed model can be a valuable tool in the analysis of nested loop rotor structures which are characteristic of brushless doubly fed machines. Two-dimensional FE analysis is used to investigate basic rotor bar characteristics. Interface with a detailed simulation program permits the investigation of assembled rotors, otherwise a 3D analysis problem. Rotor bar geometries for a high-speed alternator are investigated. Bar shapes are kept simple to allow manufacturing of the rotor in the absence of die-casting equipment. Rotor prototypes are constructed using custom, laser-cut laminations, and experimental results for the alternator are investigated. Bar shapes are kept simple to allow manufacturing of the rotor in the absence of die-casting equipment. Rotor prototypes are constructed using custom, laser-cut laminations, and experimental results for the alternator verify improved line-to-shaft efficiencies over conventional rotor geometries as well as off-the-shelf alternators. >