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

["Jon \"Sheer\" Pullen" <sheer@brassrat.net>]

> David Dymaxion wrote:
> > Car without regen burns up brakes down a hill = big lawsuit.
> > Solution: AC.
>
> Except that normal cars don't have regen; they get along just fine. And
> regen can be done with any motor, AC or DC. It is exceptionally easy
> with sepex DC, for example.

Sure they do. Take your foot off the throttle in any normal car and the
engine will turn into a compressor, slowing the car down and heating up the
coolant.  Often on big hills with heavy loads this type of braking is the
only thing that gets you to the bottom with your brake pads intact.

> > 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.

On the other hand, 336 volts is a lot more likely to do permanant damage to
you than 120.

> The auto companies don't have any problem building even the simplest
> things so they are impossible to fix!

[laughs] true, true.

> > 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.
>
> As we've discussed before, the wide power band is not intrinsic to AC;
> it's a consequence of a purpose-built drive system. Trains and buses
> have used DC traction motors and direct drive for many decades -- they
> work, too.

But AC has certain attributes which lend themselves to a wide power band.

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

This is why we need to mass produce EVs.