Re: domestic micro wind power

In message <3hh832pn9ilvnbb6l2gn22rhlc5gsbmq9h@xxxxxxx>, AJH <sylva@xxxxxxxxxxxxx> writes
On Tue, 4 Apr 2006 22:24:57 +0100, John Beardmore
<wookie@xxxxxxxxxxxxxxxxxx> wrote:


Hmmm... I've heard of 1.2kWt heat pumps with start up surges of over
90A at 240V. What battery current would that be ? 1800A at 100%
efficiency seems a lot to ask, not so much of the batteries but the FETs
in the inverter. I know they are tolerant devices, but if this happens
a few times a day, I wonder how long they'll last ?

There are other ways of skinning this cat, we have 3ph motors on our
dryer fans run from the single phase supply, the motors can be started
at slow speed and gradually brought up to full power. These variable
speed controllers are cheap now as they work at mains voltage and just
chop and rebuild the waveform,

Yes - got one in the garage.

But single phase input current might still bite you when running even if you survive the soft start.


mind see below it makes more sense to
run this pump at dc low Volts.

gland seal just like on a steam engine, though I rather like the
stirling engine idea as there is no worry about refrigerant escaping.

And that is a significant issue.

It is with non hermetically sealed units. I work in a lexan glazed cab
which demonstrates how good solar gain can be, as a result it can be
well over 40C inside whilst frost is on the ground, ac is essential in
a british summer.

OK.


The refrigerant seems to need refilling each season

Fuck ! So that's eating ozone if CFC, or more likely now, an HCFC which is a dreadful greenhouse gas !


yet my home freezer has worked with no attention for many years.

Yes.


I recall some talk of car air conditioning units (as well as power
steering like on the bmw mini lookalike) moving to electric just to
avoid sealing issues.

You beat me to it...


If these units become available they will be 36V

Why 36 ?

Well the talk is of 42V which I take to mean 18 lead acid cells in
series with a fully charged Voltage of 42V, just like your 12V car
battery reads 13V just after you switch off.

OK.


The thing is if these become cheaply available because they are mass
produced for cars then the logic becomes simpler, you just run them at
reduced speed by chopping the supply to them,

Maybe - if there's no electronics in board.


chances are the motors
will be permanent magnet jobbies so electronic commutation can control
the speed.

Maybe.


I think so could fit in very well with this concept of a wind turbine
running the household's electricity and heat demand in parallel.

Yes. Any controller off the shelf ?

Business opportunity?

Not rocket science. P/90 out of a skip. Could put a nice user interface on it, but would probably be lucky to sell more than a couple.

Maybe I should extend some of the Java virtual instruments I'm writing to include some smart control modules that can be plugged together virtually and configured in software.


Cheers, J/.
--
John Beardmore
.

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