Multi-slice finite element modelling of induction motors considering broken bars and inter-bar currents

This paper deals with the finite element (FE) modelling of squirrel-cage induction motors having one or more broken bars. A two-dimensional (2D) multi-slice FE model allows to consider the position of the bar breakage (at one of the endrings rather than in the middle), the skew of the rotor bars and the inter- bar (IB) currents. The latter are effected by resistances distributed in the electrical circuit that connects the different slices of the cage. The multi-slice model is applied to a 3kW induction motor. An order-of- magnitude estimate of the IB resistance follows from a short-circuit test (with healthy rotor). Next, the effect of a broken bar and of the IB currents on the stator current spectrum is studied.

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