Re: [CAD_CAM_EDM_DRO] High freq. motor

rekmac wrote:

> I was wondering if anyone would know how to power a high frequency
> motor? I I obtained one that is for a PCB routing machine and thought
> if I can get it running, that it would be perfect for a router table
> I would like to build. It's a 1hp motor, I believe 400Hz.

I have run a Westwind air bearing drilling spindle off a standard VFD.
Many of the newer ones will go to 400 Hz. I have a Magnetek GPD-333
(made by Yaskawa) that runs it fine. This will only get you 24,000 RPM,
but that may be enough for you. You will have to hook up the braking
resistor, as these motors store a lot of energy, that has to be dissipated
when they stop. Toshiba and many other VFDs also go to 400 Hz on
the fancier models. Note that you have to work harder to make these
motors run on a standard VFD. One thing you need to do is add external
series inductors to prevent saturating the motor's stator core. I used
1600 uH bobbin-style inductors that I had handy for my spindle motor,
one inductor for each phase. (This trick was suggested by Magnetek,
and worked like a charm.) The other thing is you have to dope out
what the proper voltage-to-frequency ratio is, mostly by trial and
error. I found that my Westwind worked real well at 80 V @ 400 Hz.
On any VFD you buy, make sure you can get the full programming
manual and the full programming panel, as you will need these.

AC Tech has a VFD model that can be configured for up to 1000 Hz.
I have no idea what the premium on this model is, though.

I got my Magnetek VFD on eBay, and there are many being sold now.

Jon