Analytical modeling of balanced and unbalanced short-circuits of SMPM motors — Analyses of currents, torque and PM eddy-current losses

In this paper, the authors present an analytical modeling of short-circuit currents, corresponding electromagnetic torque and permanent-magnet (PM) eddy-current losses to resistance-limited (i.e., without eddy-current reaction field) during fault operations. Three short-circuits types are considered: on the one hand balanced three-phase short-circuit, and on the other hand unbalanced two-phase and asymmetrical short-circuits. The main results of this work are the time evolution of short-circuit currents and corresponding torque reinforced by numerical and experimental validation. Moreover, using Fortescue transformation the permanent-magnet losses are calculated during unbalanced short circuit.