ABSTRACT
The main advantage of an SF-PMSM is that it retains the torque density of regular PMSMs (in some conditions), while the placement of magnets on the stator leads to their easy cooling and to a passive salient pole rotor, so the machine may be considered thermally and mechanically rugged. However, only at best are half of all coils throw is “visited” at a moment by maximum PM flux (positive or negative); PM flux concentration is inherent to obtain the same torque in the same stator volume as for regular PMSMs. Still, “PM flux fringing” is so high with identically placed, tangentially magnetized PMs that the mass of PMs per Nm is almost twice as large with respect to regular PMSMs with the same stator volume and same copper losses.
