From what I understand Field Oriented Control is meant to be used with PMSM as PMSM has sinusoidal back EMF due to distributed stator windings.
On the other hand BLDC's have concentrated stator windings resulting in a trapezoidal back EMF.
Six Step commutation uses strictly two activated stator windings, 1 deactivated winding (lets assume 3 stator 1 pole pair motor). Whereas FOC uses variable current through all the coils to create a stator magnetic field that is always orthogonal to the rotor.
Does the concentrated structure of the BLDC stator windings make FOC performance worse, and if so why and how does it make it worse?