Operating induction motor drives with turn-to-turn faults

This paper examines part functionality of a five phase vector controlled induction motor drive following a winding fault. The ability of vector controlled induction-motor drives to continue operating with different numbers of shorted turns in one coil of the stator winding is examined. A simple thermal model of the coil is used to examine the duration the fault that can be allowed to exist before there is further degradation of the insulation. Simulation results given by a dynamic mesh reluctance model of the machine incorporate saturation and slotting effects. Shorting small numbers of turns gives very little time before further failures could occur. Shorts of large numbers of turns change machine flux levels, saturation and effective torque constant. By reducing the magnetising current, the short circuit current decreases, the torque developed improves and temperature rise is limited. Part functionality following a winding fault might aid controlled, drive shutdown or provide an idling mode in multi-actuator, aircraft, flight-actuation-systems. This could be particularly helpful with electromechanical actuators.