Re: Some thoughts about AC (was: For you, AC drive fans)

[Rich Rudman <rmanzan@tscnet.com>]

Victor Tikhonov wrote:
> 
> David Dymaxion wrote:
> >
> > Victor is being too modest about AC (he sells AC drives).
> 
> Well, I'd rather have others say about their AC systems. Personally,
> I'm thrilled with their performance and advantages, but anything
> positive I say will likely be taken as pushing the product sale.

OK then I will. Victor's Ac drives haul ass. 30Kw??? more like 100 Kw
stuffed into a 30Kw motor.
55 in first?? OK, Shift??? Why?. Yes we were doing more than the posted
limit. Yes I would have bagged a Rice burner with a Punk driving, If
only Victor had a better clutch!!
> 
> > Of course, regen can add about 10% to your range. AC has regen, few
> > DC drives do.
> >
Regen at %10. Up to %50 if you do a lot of start and stop  or BIG hills.
I got more than that increase when I was using a 2CM77 and 48 volts. It
takes practice to really get the most from a good regen system.

> > Also, AC is slightly more efficient, but just a little, certainly not
> > enough to pay many more $$ just for another 5% or so.
The motor can be the controller is not. But the difference in 99.875 and
99.50 is not really apparent.
The motor under duress can be dozzens of % more EFF in a AC than in a
DC. AC will stay on the sweet spot, all the time. 
> 

> 
> AC is boring like a Mac - you plug it and if designed right,
> it works forever, period. Nothing to do, no fireballs, copper snots,
> welded contactors and other fun stuff. Well, not significant
> disadvantage for me :-)
Well when we were all happy with 400 amp Curtii, things were a lot less
exciting. Just wait until some crazy fool comes up with a racing 250 to
500 Kw AC drive. Then we will have the fireworks again. 
I can see it now , Slagged  down rotors, Lots of steel where'd the Alum
go??? Open single phase lines, Umm lots of current on phase 1 and 3 by
why no Current ON, OH sh__! Don't kid your self, Racing AC drives will
be very exciting. Just different things to Swear at. Ducking while rotor
magnets buzz by your ears is a little unnerving. 
> 
> I also found that AC system for many is scary because unfamiliar and
> generally poorly understood. Therefore can't be fixed easily.
> 
This is why Dennis Berube is Scarred of AC. He can't tweak the motors. 

I have a lot more confidence in his abilities than that. He will tweak
what ever he's driving. But to get his attention, you have to get close.
So while he's messing with brush timing, The AC guys will be messing
with the max Slip numbers and just how far into field weakening we want
to go. Same effect, but different ways to impliment it. Too much of any
of these will result in Copper snot.


Oh Well it's fun to dream about Big AC drives... and summer is coming...
but it's 
back to  PFC20 chargers, and Ho Humm, 8.3 Kw drives....
Gotta work Like heck to play.

Rich Rudman
Manzanita Micro