Re: what is the max bus voltage, 300V?

[Victor Tikhonov <vtikhono@lsil.com>]

ethorpe@gric.com wrote:
> 
> > -----Original Message-----
> > From: Lee Hart
> >
> > That's not really the case. There are lots of examples. I have some 15
> > HP 240vdc separately excited DC motors in my garage right
> > now, in fact.
> >
> > There are AC forklift drives that run on low voltages. For
> > example, API Elmo AB (in Sweden) makes them up to 21 HP for 24-80vdc
> > battery packs.
> > --
> 
> Yes, but how heavy and large are these motors. Size and weight are major
> concerns for on-road EVs. DC motors for reasonable conversions weigh 100-150
> lbs and take 80-200vdc (like 8" and 9" ADC motors). What size are the 15HP
> 250vdc sepex? What size is an Elmo 21HP 80vdc AC forklift motor?

I'll speak for what I know, for on-road EV motors. Not ADC motors
people USE for on-road vehicles just because there is nothing better
exist. ADC was never ment to serve in a vehicle.

(BTW can anyone tell me what exactly is "advanced" in ADC motor?)

18 kW Siemens motor which will give you the same max power as 9" ADC (if
not more)
is 108 lb, 7.5 x 7.5 inches square in crossection and less than 15
inches long.

30 kW motor is 150 lb and even shorter - 13.5 inches long.

Either will sustain 80 kW of power between 4000 and 10000 RPM (as long
as you run cold water through). That means you run on first or second
gear all the time and have giant torque at the wheels.

These motors meant to be in a vehicle from very beginning, as a bolt in
replacement (EV option of ICE vehicle). Not adopted from some other 
purpose. For example the shaft splines are often made to take and mesh 
with transmission shaft directly. Motor rear mounts and brackets are 
made for bolting to the same engine supports as the target vehicle
already has. Example - VW Golf many of you probably have seen: check 
out this photo of bolt in replacement (OEM case): Siemens 1PV5105WS12 
motor being installed - http://www.metricmind.com/images/vw.jpg

I experience the difference every day. It press me against the seat
when accelerate 20 to 30 mph the same way as going 50 to 60 mph.

Try it with 9" ADC. Mathematically you can get the same torque at the
wheels (on higher gear) but practically you twist shafts and stress
gear box and the clutch beyond reliable operation.

I had 8" before in the same vehicle, so can compare first hand. 

> The main problem has been a lack of suitable motors. Almost all
> on-the-road EV motors are borrowed from some other application, so they
> are not really an optimal choice.

Precisely. Fits ADC description.

In the beginning SepEx DC could be chosen as well as AC. Why
then there are more AC OEM passenger cars while inverters still
more expensive than controllers for SepEx?

I bet Lee will find good reason. What is it Lee?

I don't believe AC is there because it's a fashion today.
I'm not defending AC because I use it. I use it because
what I have (purposely built system) is simply better than 
generic 8"ADC. If I had purposely built SepEx DC system vs
heavy 60 Hz industrial AC motor choice, I'd pick SepEx DC system
for my car (provided I could afford it). I'm glad I had other
choices, it's as simple as that.

Victor