Finite Element Modeling of Losses due to Inter-laminar Short-circuit Currents in Electrical Machines

Identification and accurate prediction of losses in electrical machines is very essential in design stage to minimize the cost and optimize the efficiency. The losses introduced in electrical machines due to manufacturing effects are significant. Burr formed due to punching on the edges of laminated sheets impairs the insulation of adjacent sheets and makes random galvanic contacts during the pressing of stacked sheets. The existence of a surface current on the boundary between two insulated regions causes discontinuity of the tangential component of the magnetic field strength. Hence, based on this principle, a boundary layer model was developed to study the additional losses on the burred edges of electrical sheets. The boundary layer model was then coupled with 2-D finite element analysis and incorporated into an inhouse FEM software to study the additional losses in a 37 kW induction machine