Permanently Split motors are quite prevalent.
Where they fall down however, is with constant stopping and starting.
They can't be used on a variable frequency drive, because, by design, it will burn the bearings out over time, with circulating currents.
This is why the Induction motor (Cage-type) has become the work-horse of industry.
With a VFD, you can have any speed you like, you can ramp up to speed and ramp down again.
