amberwolf said:
I don't know if it helps, but there's some info here
https://endless-sphere.com/forums/viewtopic.php?f=28&t=15344#p254773
about overlapping poles not working in delta very well; perhaps this is part of that "optimization" for wye?
Good link
If nothing else it high-lights the variable of how some motors use overlapping winds and shared poles and others do not.
A quick google for "delta circulating currents" also brings up some illuminating information on why this occurs and the significance of the 3rd order harmonic.
Regarding some of the other points, I've not seen (or heard of) an industrial 3 phase induction motor with hall sensors (or similar feedback) but doesn't mean they don't exist. Uncommon/non-standard usually indicates something is an exception to rules of good practice. Same with caps on a 3 phase motor. Start & run caps on a single phase machine make sense as the phase difference produces a rotating magnetic field - something you get automatically on a poly-phase machine.
Basic theory, rules of thumb and standard practice are usually suitable to provide a first-order indication of whether an idea is good or not. Then delve deeper into the technical details if it looks promising, or the potential rewards are so great it's worth chasing even though it's unlikely to subsequently turn out to be good.
In this case, the starting claim is "significant performance gains between wye & delta"
First order assessment: Basic theory says same motor/windings/iron = same performance for both
Second order assessment: Actually, there are circulating currents in delta, so potentially there is a difference
Third order assessment: Actually, this depends on the specific motor construction and ranges from a small difference in efficiency to unusuable
Fourth order(?): Check out specific motor designs to see what difference there is.
Each steps takes more time/money/effort and narrows the potential benefit and my personal preference is to filter out a lot of ideas at the first step. There is a chance of missing one that's actually good, but it saves a lot of time (which can be spent productively developing other ideas).
