hmm, I was thinking for field oriented control as something similiar to field weakining, where the controller is actively looking for (i.e. with a PID) the minimum amount of current needed before slipping occurs. Maybe I'm just still confused
I get the flux angle bit, sorta, no point pulling when you should be pushing, or doing nothing. But with fine grained speed control, I guess you could detect a slowdown more quickly is all I can think of. Perhaps FOC would feel jerky if you had a chunkier speed sensor (i.e. 3 hall sensors)?