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

[David Dymaxion <david_dymaxion@yahoo.com>]

I find this a very interesting question, and think you bring up a
good point, Victor. My guess is it is ultimately economic reasons,
believe it or not!

Car without regen burns up brakes down a hill = big lawsuit.
Solution: AC.

DC system is easy to modify, customers start adding things like
bypass contactors, raising the voltage. Could lead to an expensive
lawsuit. AC is much harder to tinker with.

DC has full on failure modes. Remember all the grief Audi got over
the sudden aceleration thing? It is harder (though not entirely
impossible) for AC to fail full on.

Foreseeably silicon will be cheaper than the copper and iron motor,
so eventually it could be cheaper to put more into the controller,
and use a cheaper common AC motor.

Gearboxes are only cheaper for converters because it is already there
-- try pricing a new transmission for fun sometimes! Wide AC
powerband helps save on tranny cost when designing from scratch.

Advertising: Do you want to say you are using 100 year old technology
or the latest and greatest?

What has surprised me is sepex hasn't been more popular, it seems
like a good compromise between AC and DC.

--- Victor Tikhonov <vtikhono@lsil.com> wrote:
> Lee Hart wrote:
> > 
> > Victor Tikhonov wrote:
> > > There are practical advantage of working with smaller wire...
> > 
> > Yes, this is certainly true. There are many little reasons for
> picking
> > high voltage or low voltage. But the key point is that there is
> no
> > fundamental reason why one is better than the other.
> 
> Lee, if that would be so, OEM would built 50% low voltage cars (DC)
> vehicles and 50% hi voltage (AC) ones. This is not the case
> however.
> 
> Granted, in your "fundamental reasons" you don't include non
> technical
> issues like prices, liability if system fails, serviceability, etc.
> 
> Still, it's like >80% hi voltage OEM systems and <20% low voltage.
> For buses it's like 100% to none. You won't find decent 120VDC bus 
> anywhere.
> 
> I'm not steering opinion, just observing the trends.
> 
> Victor
> 


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