Changing motors is not an easy option, especially since there will be complex 
mechanical changes.  What does "bridge switcher" mean?

I also just mentioned a thought about vehicle power inverters on another email 
a minute ago.

But from this and other sources, I see that it's not such an easy task, so 
what if I scale back a bit...  Rather than running multiple motors off a 
single boost converter, if I simplified it as one boost converter for each 
motor, I'd need 18V-20V at 10A-12A.  We're still up around the 200W mark, so 
my next thought would be to parallel 2 or more boost converters, if that's 
allowed.  I guess that may be dependent on the specific regulators.

Cheers,
-Neil.


On Sunday 24 September 2006 11:34, Harold Hallikainen wrote:
> I think the most efficient approach would be to use motors that are rated
> for the battery voltage. Failing that, I suspect a bridge switcher driving
> a transformer is the most efficient way to get a relatively high power to
> a higher voltage. A typical boost converter (which I consider a form of a
> "flyback converter") becomes impractical above 100 or 200 watts.
>
> Harold
>
> > On Sunday 24 September 2006 10:46, Xiaofan Chen wrote:
> >> What is the requirement for the boost converter? For example,
> >> the input and output voltage, the efficiency requirement. Depending on
> >> the requirement, the design will be totally different.
> >
> > Input is automotive voltage -- say 10V to 14V.  Output is approx 20V, and
> > the
> > higher current will be used to power some motors.  Efficiency is "as
> > efficient as possible, within reasonable cost".  It's not a portable
> > battery-powered device, so it does not have to be 99% efficient, yet,
> > given
> > the current requirement, I'd like it to be as efficient as possible so
> > that
> > there's less heat to be dissipated.  I know that's very shady, but I'm
> > not familiar with the high-current design, so I would evaluate various
> > efficiencies vs. cost ... that is, IF I have choices.
> >
> >> 50A is not small current. 50A @3V will be 150W. 50A@24V will be
> >> 1.2kW and the design approach will be very different.
> >>
> >> The design which fits 1A@3V will not fit for the design of 50A@3V
> >> since the loss on the diode will be too much and you may have to use a
> >> synchronous boost design.
> >
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