Dynamic and steady-state operation of a five phase induction machine with an open stator phase

The analysis of an open phase fault for a five phase induction motor is presented. A circuit based model is developed which can help to predict not only the steady-state performance but also the dynamics including the pulsating torque and to evaluate the small-signal stability of the faulted machine. This is made possible by the utility of the harmonic balance technique on the model of the machine in the stationary reference frame. The resulting model is used in determining the small-signal stability of the five-phase induction motor under open-phase fault. At low speeds the machine exhibits instability on the rotor flux linkages but it is stable at higher speeds. Simulation results and steady state results are presented which also predict the speed harmonic components as well as the torque pulsations.