Comparison of Different Fault-Tolerant Control Strategies for Seven-Phase Induction Motor Drives

In this paper some different control strategies, suitable for open-phase fault operation of seven-phase current regulated induction motor drives, are presented. These strategies, which are valid in steady-state as well as in transient operating conditions, are compared in terms of stator and rotor copper losses and torque pulsations. The comparison is carried out by means of an opportune mathematical model of the machine that, exploiting the properties of the multiple space vector representation of multi-phase systems, takes into account the first five spatial harmonics of the air-gap magneto motive force. Some experimental tests carried out on a seven-phase asynchronous motor drive prototype confirm the characteristics of the proposed control strategies and the results of the theoretical comparison.