Speed contol of AC motors

Robin,

Life is will be much more complicated, or at least expensive. Much has been written about single-phase motors & variable-frequency drives: check google groups for VFD & single-phase motor, there're far too many points to repeat in full here.

It boils down to not being worth the hassle: having to start at full speed then reduce because of high start current, significant lack of torque at low speeds (the worst feature), increased motor hum, minimum speed limited by the presence of a centrifugal starter switch, and burning-out the starter winding by using it too much. Additionally, I've never seen a 1ph VFD - they generally have 3ph outputs, so getting one to use just 1ph of these is crazy.

If you want variable speed, get VFD's and 3-phase motors. If this is too expensive & you don't care about going deaf, use reclaimed commutator motors from washing machines, with a phase-control speed regulator circuit (search

HTH Guy

Try Newton tesla

Can't be done with AC single phase motors. You need to switch to 3 phase to be able to fit an invertor.

-- Regards,

John Stevenson Nottingham, England.

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