Influence of end-ring shape on induction motor performance

The objective of this paper is to examine the effect of end-ring shape on the rotor resistance of a cage motor. The procedure for choosing a particular ring shape is a significant feature of the paper. This could be achieved on a simple `trial-and-error´ basis covering a rather large number of possibilities. A more satisfactory and rigorous approach is to incorporate the calculation of the ring impedance into a formal constrained-optimisation algorithm. The problem is then reduced to specifying what is required from the new ring shape. The optimisation procedure attempts to determine the best ring shape to meet the user´s specification. The paper therefore describes the coupling of the circuit-based ring model to a formal optimisation procedure for choosing the most effective ring cross-section. The means of incorporating any ring shape into the conventional equivalent circuit is outlined