Mark E. Skeels wrote:
> I suppose you will now tell me.....

I'm not Dave, but:

>     * It's really simple

At your power levels (150W if I remember right), it's a bit more than
"simple".  That's 1.4A back to a 110V power line.

For low powers and simple, you can dump your power onto a cap, which you
then discharge thru a diode during the falling half of the positive half of
the power sine until it goes below some threshold voltage.  The cap is big
enough to that it doesn't build up too much voltage during the time it's no=
t
being discharged to the power line.  The dumping the power onto the cap par=
t
is just a boost converter, except that its feedback regulates the input
current or voltage instead of the output current or voltage.  The cap just
builds up voltage according to Volts =3D Sqrt(2 * Joules/Farads) until the
next dump to the power line.

At 150W however, you probably need to wake up and do it right, even if powe=
r
factor regulations don't force it.  You still dump power to a cap the same
as before, but now you've got a reverse PFC circuit maintaining the cap wit=
h
about 200V and dumping current onto the power line in little pulses
proportional to the instantaneous power line voltage.  This is simpler than
a real inverter, since the power line is there and you can consider it a
voltage source.  This is basically a "electronic load" circuit meant to
handle more than trivial amounts of power.

>     * any real/qualified EE should be able to do this

Well, um, actually yes.

>     * I am morally obligated to do this

Not really.  The decision whether to do this or just dissipate the power
depends on a lot of things, mostly economic considerations you haven't told
us about.  However, heat sinks, fans, and the extra space to put them
someplace, weight to ship them, etc, aren't cheap.  I don't know the detail=
s
of your sitation (and don't care, you're problem, you figure it out), but i=
t
may well be cheaper to handle the power by dumping it back onto the power
line than to deal with 150W of heat.  Compare the cost of a few FETs, caps,
inductors, and a dsPIC to that of a heat sink and fan, not to mention
reliability costs which inevitably happen when things get hot.


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