Analysis and design of a fault-tolerant six-phase permanent-magnet synchronous machine for electric vehicles

The six-phase permanent-magnet synchronous machines (PMSMs), which use open winding concept and possess six degrees of freedom, is suitable for electric vehicle (EV) driving system for their high torque density, high efficiency and high fault-tolerant capability. Considering machine design, the possible slot and pole combinations are given and compared; a 24-slot/22-pole all-teeth-wound scheme is proposed and designed; the winding factor for all-teeth-wound winding is derived in detail, which is different from conventional double-layer winding; the eddy-current loss of permanent magnets is reduced by using segmentation technique. The fault-tolerant control for one and two-phase open faults are introduced through reconstructing a circular rotating magnetic field. In order to find the causes of torque ripple and excessive iron losses in the unbalanced phase-deficiency operation. The air-gap MMF harmonics in healthy, faulty and fault-tolerant controlled modes are analyzed.