> I'm pretty sure this isn't the answer you were hoping to
> see
Yes, it isn't. :-)

I am looking to make a sort of supply unit that puts out
variable frequency at 220VAC. So when I need to grind
welds on corners of a MS box, I run the wheel at high
speeds. When I need to polish SS run the buff at
a much lower speed. When I drill a hole in wood, the drill
is run at high speed and for metals at low speed... Not 
individual controllers for each tool but a variable 
frequency 'power supply' rated for the biggest and can be 
used for the smaller ones.

Mohit.


>> -----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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