Performance Comparison of Stator Winding Connections in Multiphase Drives Under Open Converter Leg

Multiphase machines provide various significant benefits when compared to three-phase ones. In particular, their inherent fault tolerance is often considered their most attractive advantage. Among the possible types of faults, the case of an open converter leg is especially common. On the other hand, multiphase machines with symmetrical winding arrangement offer multiple possibilities for stator winding configurations (SWCs). It has been recently proved that, in five-phase machines under open converter leg, the pentagon SWC attains smaller copper loss (SCL) and larger maximum achievable torque (MAT) than the conventional star SWC. However, it is currently unknown if such conclusion also holds true regarding machines of greater phase numbers and other SWCs, and if so, to which extent. This paper compares for different SWCs and phase numbers the performance of multiphase machines under open converter leg in terms of MAT (derating factor) and SCL. It is shown that the most convenient SWC for all phase numbers is to connect each phase in series with the neighboring ones. In particular, with such SWC the enhancement in MAT with respect to star SWC increases drastically for phase numbers greater than five, becoming very close to the healthy MAT. Simulation results support the theoretical study.