[Oeva-list] vfd's and ac

Nev Okyay nevokyay at yahoo.com
Tue Oct 21 21:03:55 PDT 2008


Hi Larry-

thanks for the info below.  when I was looking
for inverters I remember that Curtis made only
DC motor controllers.  At least that's what I
saw from the evalbum web site.  I guess you are
right that they do make AC motor controllers as
well.

Again, when I was looking for AC motor controllers
I saw two 3 phase AC controllers: Siemens controller
which required a Siemens motor, and azure controller
from Italy.  There was hardly any documentation
on the azure.

On the Hitachi drives I still haven't figured out
how to wire for the regenerative power.  There are
two terminals to connect a load resistor and that's
where the controller is supposed to dump the
regenerative power.  The second possibility is 
that the regenerative power appears on the DC 
bus and if the voltage is greater then the battery
voltage, it automatically charges the battery.
Does anybody know how this is supposed to work?

thanks


--- larry <larry at energyventuresllc.com> wrote:

> 
> For those interested in using VFD's on straight DC
> it's really not a big 
> deal to bypass the rectifiers by going directly to
> either the brake buss 
> or go to the capacitor buss
> They are both on the DC side of the rectifiers
> That eliminates the derating problem
> Hitachi is real open and easy hookup
> Allen Bradley on small units is bit of a pain
> Yaskawa is another good one that's easy to work with
> Just remember that if you are running a 240 or 480
> VAC you need 240 or 
> 480 times 1.414 to get proper peak to peak voltages
> 
> I have several VFD's in the field running large AC
> irrigation pumps 
> directly off of the PV
> My largest is on a tree farm in Borrego California
> It uses a 250 HP Allen Bradley and works fine if you
> program it correctly
> It's 480 volts so I had to violate code a bit in
> going over 600vac open 
> circuit but big deal.
> 
> As for AC motors I don't know why you would want to
> build your own with 
> a VFD since Curtis makes a great inverter up to
> about 500 amps at 130 
> volts such as the 1238
> I buy my motors in lower voltage 180 frame from
> HiPerformanceGolfCars.com
> Bill and Bryan custom wind a great motor and at
> $3200 for motor and 
> inverter and instrumentation it's a bargain compared
> to using a VFD
> The algorithims are not the same as a dedicated
> traction inverter
> VFD's in an auto application are pretty funky
> I did use them when building Air Conditioning units
> on my EV's but as a 
> driver it's pretty bad
> 
> I now have a 1999 RAV4 PHEV with the AC drive just
> about ready to roll 
> out the door
> Just waiting on my LiFe batteries to arrive
> Still has the gas motor and tranny but also will
> drive up to 20 miles on 
> pure sunshine electrons
> 
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