> -----Original Message-----
> From: piclist-bounces@mit.edu 
> [mailto:piclist-bounces@mit.edu] On Behalf Of Gmail Lists
> 
> Is it possible to design a single phase VFD to control speed 
> of motors - 220VAC, 1Ph, 50 Hz, 2kW?  The designs I've found 
> are controllers for 3 phase motors.
> 
I looked into this too, and concluded that the answer is "Yes, but..."
it's far better just to replace the motor. If you live near a large city
there will probably be industrial salvage yards nearby. Here in the
Seattle area, we have Pacific Industrial (maybe others, but that's the
one I'm familiar with). They have an *enormous* pile of used 3ph motors.
Everything from fractional HP up to monster motors, all of them
available for a fraction of the cost of a new motor. 

VFD's are available for < $150, the motor should be well under $50. I
doubt you could build a controller for that especially if you value your
time. And, you would have to modify your motors because the centrifugal
start switch must be disabled and replaced with an electronic starting
circuit.

I'm pretty sure this isn't the answer you were hoping to see, but it is
the practical answer. On the bright side, used single-phase motors
having a form factor suitable for home workshop equipment tend to bring
a decent price on eBay. Figure that into your calcuation when you're
deciding what a motor swap will cost.

Regards,
   Glenn Minch

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