Comparative Design of Ferrite- and NdFeB-PMSMs using the (x,b) Design Plane

In this paper, two permanent magnet synchronous motors for traction application are designed and compared using the open-source design platform SyR-e, the first one using NdFeB magnets and the second ferrite magnets, as a rare-earth free alternative. The core of the adopted design method is the (x, b) plane, where a number of performance indicators are shown function of the two geometric parameters x and b of the machine cross-section. Performance figures are calculated using approximated design equations, corrected with the fast finite element analysis FEAfix approach, to obtain FEA-like accuracy with a limited computational effort. New figures of merit have been added to the plane to visually match the output figures and the design constraints. Special attention is devoted in this paper to the ferrite-magnet motor and its demagnetization limit. Because of the low energy density and coercivity of ferrite magnets, this motor will need an increased stack length and inverter current rating. Besides the direct comparison of the two motors throughout the design and FEA identification steps, the paper also gives a complete overview of how SyR-e is used for fast preliminary motor design starting from design specs and target figures.