Fault tolerant and minimum loss control of double-star synchronous machines under open phase conditions

In this paper, a new method for filtering the torque pulsations is proposed for double-star permanent magnet synchronous machines under fault conditions. The machine is supplied by two independent electric sources via two voltage source inverters. The proposed method deals with the case where an open-circuit fault occurs. To reduce the torque pulsations, the usual solution consists in supplying only the healthy star winding. Here, we propose to supply not only the healthy winding, but also the two remaining phases of the other star winding by the healthy legs of the faulty inverter. The stator current waveforms can be easily determined to minimize the copper losses while reducing the torque pulsations. Simulation and experimental results confirm the efficiency of the proposed method.