Analytical model of multiphase permanent magnet synchronous machines for energy and transportation applications

Multiphase (more than three) electric machines and drives were used first to limit current amplitude and later reduce torque ripple with early, six-step converters. More recently, the potential benefits of multiphase drives for electric ship propulsion include improved fault tolerance, improved torque density by harmonic injecting, reduced per-phase power rating, reduced ripple torque, reduced rotor loss, and reduced noise. Since the mid 1990s, R&D effort in the area of multiphase machines and drives has accelerated for new aerospace, electric vehicles, and renewable energy applications, especially off-shore wind because of reliability and size. Among the many multiphase options, N×3-phase systems can be split from existing 3-phase windings and still use conventional 3-phase inverters. This paper provides the analytical synchronous-frame d-q model of the 2×3-phase permanent magnet synchronous machine (PMSM), similar to the conventional three phase d-q model, for the purpose of control development. The developed model is verified with FEA simulation results. This paper also presents how to calculate and scale the parameters of the 2×3-phase PMSM from the baseline 3-phase PMSM. Motor drive engineers seeking the same level of 2×3-phase and 3×3-phase PMSM model as the conventional 3-phase PMSM for control research and development can benefit from this study.