Single phase variable control motors?

Hi, I am trying to find an electrical hoist, which has variable speed, single phase motors. I am unable to find any. Is there a technical
reason why? Or would it be a business reason? Any insight?
Thanks.
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Dear P-GPS:

Single phase motors are fractional to small integer horsepower. You will need VFD-rated motor windings, and make sure that you do not overspeed the winding mechanism (so don't run the mechanism over 60 Hz, for example).

Small market, you are going damned slow anyway so why worry about slower, the single phase inverter is at least 2x more expensive than the three-phase version for the same motor power, control logic for reversing the motor is orders of magnitude more complex, stuff like that.
I suggest you find a vendor that offers hoists with less than 5 hp drive motors, and single phase power is probably an expensive option.
David A. Smith
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Hi, I did not get you in some of your statements

What does this mean?

Doesn't a speed controller limit the frequency to 60Hz, when connected to a 60Hz main?
Even if the cost of a single phase motor is 2x that of a 3-phase motor, we would like to get it. Are there any vendors who sell single phase variable motors?
Thanks.

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Dear P-GPS:

They are small motors. < 5hp.

No. You can obtain VFDs that will overspeed by 20% or more, with modifications they even run ozone generators at thousands of hertz.

For < 5hp, or over 4000 volts, you can get them. If you wanted to pay 100x, you could get someone to make you one.

The motors are not variable, the drive is. And switching it from "raise" to "lower" is much more complex than with a three phase motor, and requires a whole 'nother control system.
David A. Smith
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