On Mon, 8 Jul 2002, Mike Singer wrote:

>Olin Lathrop wrote:
>.
>.
>.
>> I wouldn't tackle a 1.2KW inverter with sine wave output as a "first"
>> amplifier project!  There is a reason these things are expensive,
>> and that there are people who specialize in such circuits.  Don't try
>> this at home. Mistakes at these voltages and powers can be
>> seriously dangerous.  Things go BANG and you can end up
>> dead and your house a pile of smoldering cinders.
>.
>   Agree.
>   Much more safe way is to get UPS (uninterruptable power supply)
>to the project. The one with cool start ability (may be started on
>accumulator batteries without 220v). The best way is, as for me,
>to emulate an accumulator battery by system consisting of sun
>battery, accumulator battery and PIC-based controller.
>Will work under clouds, will stand overload.

Does it not make a lot of sense to use a high voltage DC storage battery
and a sine former (using magic sine etc) and to charge it with a dc/dc
upconverter from the solar panels and/or a wind generator and/or mains
grid and/or generator for such power levels ? Because I think that it
*significantly* reduces switching and I^2R losses at high load time. With
~8-10 24V batteries in series and charge equalization control this could
supply significantly more than 5kW for a short time. The lower current per
battery would mean that inexpensive smaller batteries could be bought in
bulk. At 5kW the current would be somewhere near 60A (120V system,
including something for efficiency). This is permissible even for small
tractor starting batteries. The upconverting solar charger could be of the
optimal energy transfer type (easy with this config). A failed battery can
be removed from the system and its place shorted over with very little
change in output parameters (though not without a short power break).

Peter

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