Investigation on effects of non-active peripheral machine parts to the impedance of rotor end rings in induction machines

Determination of the end-ring impedance in induction machines can be done by means of finite element analysis (FEA) as well as analytical approaches. With both methods, the frequency-dependent skin effect as well as the magnetic influence of the iron core can be considered. So far, the effect of other surrounding elements as the machine shaft, the machine housing and the bearing shield is mostly neglected. Therefore an overview of the influence caused by different peripheral structures of the machine´s end-winding section is provided by extensive FEA, comprising the magnetic as well as the electric characteristics of the surrounding elements. As a result a guideline for setting up boundary conditions according to the peripheral structure is given and existing analytical models are extended for the applicability of further magnetic boundary conditions, showing good accordance with FEA results.