Comparisons of three-phase and five-phase permanent magnet assisted synchronous reluctance motors

This paper presents the comparison of three-phase and five-phase permanent magnet assisted synchronous reluctance motors (PMa-SynRM) in terms of their design and performance characteristics. With higher fault tolerant capability, efficiency, and reliability, the five-phase PMa-SynRM can be a better substitute when compared with the three-phase PMa-SynRM in critical applications where safety is top priority. In this study, for a fair comparison, same design procedure using in lumped parameter modelling is followed in developing the three-phase and five-phase PMa-SynRMs. The models are optimised to minimise cost and maximise efficiency. For further detailed comparison of the three-phase and five-phase PMa-SynRMs, two-dimensional finite element analysis (FEA) is utilised. Performance characteristics such as torque pulsation, back electromotive force, flux linkage, d- and q-axis inductances versus their respective currents, cogging torque, efficiency plot, and torque-speed characteristics are intensively simulated through FEA. The optimised three-phase and five-phase PMa-SynRMs are fabricated with the same power rating (3 kW) and same volume. Experimental tests are conducted on the prototypes to validate the simulation results.