Estimation of additional losses due to random contacts at the edges of stator of an electrical machine

Abstract

Purpose

Punching of the electrical sheets impair the insulation and make random galvanic contacts between the edges of the sheets. The purpose of this paper is to model the random galvanic contacts at the stator edges of 37 kW induction machine and estimate the additional losses due to these contacts.

Design/methodology/approach

The presence of the surface current at the edges of sheets causes the discontinuity in the tangential component of the magnetic field. The surface boundary layer model which is based on this concept is implemented to model the galvanic contacts at the edges of the sheets. Finite element analysis based on magnetic vector potential was done and theoretical statistical study of the random conductivity at the stator edge was performed using brute force method.

Findings

Finite element analysis validates the interlaminar current when galvanic contacts are present at the edges of electrical sheets. The case studies show that the rotor and stator losses increases with the thickness of the contacts. Statistical studies show that the mean value of total electromagnetic loss was increased by 7.7 percent due to random contacts at the edges of sheets.

Originality/value

The novel approach for modeling the galvanic contacts at the stator edges of induction machine is discussed in this paper. The hypothesis of interlaminar current due to galvanic contacts is also validated using finite element simulation.

Citation

Shah, S.B., Rasilo, P., Belahcen, A. and Arkkio, A. (2015), "Estimation of additional losses due to random contacts at the edges of stator of an electrical machine", COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, Vol. 34 No. 5, pp. 1501-1510. https://doi.org/10.1108/COMPEL-02-2015-0083