Analysis of Fault-Tolerant Multiphase Power Converter for a Nine-Phase Permanent Magnet Synchronous Machine

The use of electrical drives and machines with very high number of phases is not a common topic of researchers, because of the control difficulties and the important number of switches needed to assure the operation in faulty conditions. The advantage of using a high number of legs/phases provides smooth mechanical performances (i.e., reduced torque ripples), without increasing the number of poles (this last approach, is usually applied for fractional-slot machines, increases frequency, and consequently the iron loss). The authors are proposing a nine-phase drive to supply a permanent magnet synchronous machine. A prototype of nine-phase drive machine is constructed. Its capability to operate in faulty conditions will be evaluated by numerical computation and tests. It will be proved that the proposed solution can operated even in the most severe faulted conditions (78% of the drive machine being faulted).