Re: Synchronous Induction Motor

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: Jim Lux <jimlux-at-earthlink-dot-net> 

At 08:19 AM 4/16/2004 -0600, Tesla list wrote:
>Original poster: "Stephen Mathieson" <s.mathieson-at-charter-dot-net>
>That is exactly what I have though I was not aware of this resynch. problem.
>I chose not to use this motor as I have taken another approach which I feel
>may be of interest to others.
>
>I purchased a 3 phase 1 1/2 HP 3450 RPM induction motor and am driving it
>with a variable speed AC drive. (These are usually available on e-bay for
>reasonable prices.) Most drives will take a single phase input and create 3
>phase output at up to 120Hz. I am planning on using feedback from my rotor
>to close a PLL driving the speed control input. Ideally I will be able to
>run the gap in synchronous mode and control the firing angle or open the
>loop and run it async. up to 6900 RPM.
>
>It is still under construction and I will post my results. I also welcome
>comments from any others who may have tried this.
>
>Stephen A. Mathieson
This is a way cool way to do it.. And, as you say, I'll bet you can find 
old style low switching frequency motor drives cheap.  We used to have a 
bunch of them using conventional transistors (low kHz switching rates), and 
you could run them with single phase input, with a reduction in power (and 
some ripple in the torque).

ALmost all of them have some way to sync them (although it might require 
getting the service manual out to figure out how.. it's usually some sort 
of option board).