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

[Lee Hart <leeahart@earthlink.net>]

Lee Hart wrote [not intending to incite another AC vs. DC war]:
>> 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.

Victor Tikhonov replied:
> Lee, if that would be so, OEMs would built 50% low voltage cars (DC)
> vehicles and 50% hi voltage (AC) ones. This is not the case however.

In fact, it *is* the case. Almost all of the golf carts, NEVs,
industrial vehicles like fork lifts, etc. are low voltage DC systems.
The ones using AC are primarily in the high-end cost-is-no-object
prototype EVs built by the major auto companies.

GM uses AC in the EV1, but DC in the Club Car NEVs they are planning.
Daimler-Chrysler uses AC and Sepex DC in their EV minivans. Ford used AC
in their Ranger pickup EV, and I'm not sure which in the Think City.

> 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 a decent 120VDC bus
> anywhere.

The bigger the vehicle, the more power you need. There are sound design
reasons to keep both the voltage and current reasonably close to each
other. Thus we see 36v in golf carts, because they can cruise at 25
amps; 96v in a VW Rabbit EV that cruises at 50 amps; 144v in EV pickups
that cruise at 100 amps, etc. By the time you get to something as big as
a bus, it's going to use 300-600v and similar currents.

> I'm not steering opinion, just observing the trends.

Understood. 300v EVs are fashionable at present. It's an expedient
solution; the engineers can borrow their designs from industrial AC
motors and controllers.
--
Lee A. Hart                Ring the bells that still can ring
814 8th Ave. N.            Forget your perfect offering
Sartell, MN 56377 USA      There is a crack in everything
leeahart_at_earthlink.net  That's how the light gets in - Leonard Cohen