RE: [TCML] homebrew VFD?

[Yurtle Turtle <yurtle_t@xxxxxxxxx>]

Are your VFDs 440 single phase to 440 three phase? If not, it would take a typical hobbyist more than a simply step up transformer to use them.

--- On Mon, 5/10/10, William Noble <william_b_noble@xxxxxxx> wrote:

> From: William Noble <william_b_noble@xxxxxxx>
> Subject: RE: [TCML] homebrew VFD?
> To: "Tesla list" <tesla@xxxxxxxxxx>
> Date: Monday, May 10, 2010, 4:55 PM
> 
> a VFD putting out a square wave will do really nasty things
> to a motor or transformer - and you are working really hard
> to do what you can buy cheaper - for example, I have some
> small VFDs that are 440V input, so they are hard to sell to
> a home hobby person - I got them inadvertently - instead of
> making a VFD, you could just step your 110 up to 440 and use
> one of these things and get all the nice features of a VFD
> such as torque control and full RPM from near zero to >
> 60 hz (you can find the units on my web site,
> wbnoble.com).  Small 3 phase motors are cheap, when you
> get them used, and 440V ones are even cheaper so my
> recommendation would be to use a true 3 phase motor and a
> real VFD.
>  
> > Date: Mon, 10 May 2010 14:27:40 -0700
> > From: yurtle_t@xxxxxxxxx
> > Subject: Re: [TCML] homebrew VFD?
> > To: tesla@xxxxxxxxxx
> > 
> > I assume you're trying to make a single phase VFD. I
> ran a single phase motor from a 3 phase vfd by disabling
> it's phase imbalance monitoring. It worked OK up to a point.
> If I ran it too slow, the motor's internal centrifugal
> switch started disengaging. I considered adjusting the
> weights, so it would engage at a lower speed, but ended up
> buying a 3 phase motor. My smaller sync motor doesn't have
> this switch, so I'm sure it would have worked just fine.
> > 
> > Adam
> > 
> > --- On Mon, 5/10/10, Scott Bogard <sdbogard@xxxxxxxxx>
> wrote:
> > 
> > > From: Scott Bogard <sdbogard@xxxxxxxxx>
> > > Subject: [TCML] homebrew VFD?
> > > To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
> > > Date: Monday, May 10, 2010, 1:34 PM
> > > Greetings all,
> > >      While my intentions with this
> are
> > > completely off topic, the information could be
> extremely
> > > helpful for those running asynchronous rotaries,
> and I know
> > > of nobody else to ask this question, thus I fell
> no guilt
> > > putting it here.  I want to know if it is
> possible to
> > > essentially build a variable frequency drive,
> this is what I
> > > had in mind.  Get a mot, remove the windings
> then make
> > > your own to take 36V to 120V.  Drive the
> primary with a
> > > variable flyback type inverter, designed for
> 1-120 Hz. 
> > > So we have a DC square wave entering the
> primary.  On
> > > the secondary put a capacitor sized to take a
> square wave
> > > and make it nearly sinusoidal (so perhaps a cap
> resonate
> > > with about 90 Hz?).  And then feed your
> secondary into
> > > your induction motor winding.  It seems to
> make sense
> > > in my head but it seems a bit too simple, perhaps
> the square
> > > wave will not really drive the mot core correctly
> because of
> > > saturation in which case I don't know what to
> do.  Any
> > > thoughts or should I just abandon this.
> > > 
> > > Scott Bogard.
> > > _______________________________________________
> > > Tesla mailing list
> > > Tesla@xxxxxxxxxx
> > > http://www.pupman.com/mailman/listinfo/tesla
> > > 
> > 
> > 
> > 
> > _______________________________________________
> > Tesla mailing list
> > Tesla@xxxxxxxxxx
> > http://www.pupman.com/mailman/listinfo/tesla
>     
>         
>           
>   _______________________________________________
> Tesla mailing list
> Tesla@xxxxxxxxxx
> http://www.pupman.com/mailman/listinfo/tesla
> 



_______________________________________________
Tesla mailing list
Tesla@xxxxxxxxxx
http://www.pupman.com/mailman/listinfo/tesla