A Generalized Fault-Tolerant Control Strategy for Five-Phase PM Motor Drives Considering Star, Pentagon, and Pentacle Connections of Stator Windings

In this paper, a generalized optimal fault-tolerant control (FTC) technique is proposed for open-circuit faults in five-phase permanent-magnet (PM) machine drives. The proposed FTC technique considers pentagon and pentacle connections of stator windings in addition to conventional star connection. Open-circuit faults in stator windings of the machine as well as switches of the inverter are analyzed. The optimization objective is to produce ripple-free electromagnetic torque with minimum ohmic losses under open-circuit fault conditions. This is achieved by a simple closed-form equation to calculate reference optimal currents in all cases where a lookup table is utilized to represent the effect of fault type. The proposed FTC technique is easily extended to PM machines with higher number of phases. Experimental results for a five-phase PM machine drive are provided to demonstrate the proposed FTC strategy. In addition to single and double faults, which are analyzed for five-phase machine with star connection, triple-phase faults are also considered in pentagon and pentacle connections.