Tooth-flux distribution in slotted solid iron rotors

Abstract

The paper presents a detailed set of experimental results for the flux distribution inside slotted solid iron rotors with and without end rings when subjected to alternating and rotating magnetic fields over a range of frequencies from 5 to 50Hz. The experimental results reveal that the flux distribution inside the tooth and inside the slot are radically different, and that, in the rotors with end rings, for all practical purposes, the flux confines itself to a small depth close to the tooth and slot profile, even at a frequency of 5 Hz. The experimental results for the flux distribution are compared with the results obtained by two methods of analysis available, namely: method 1, based on the concept that the tooth and slot profile in a flux line, and method 2 based on the assumption that the slotted region can be replaced by an equivalent homogeneous medium. From this comparison, an important conclusion is drawn that for machines with end rings the field model on which method 1 is based is a realistic one conforms closely to that observed experimentally.