switching power supplies w/o harmonic currents

Are there any good designs for switching power supplies that can pull current
through the entire AC full wave cycle (1 phase or 3 phase)?

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| Phil Howard KA9WGN | http://linuxhomepage.com/ http://ham.org/ |
| (first name) at ipal.net | http://phil.ipal.org/ http://ka9wgn.ham.org/ |
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[John Popelish]

phil-news-nospam@ipal.net wrote:

Are there any good designs for switching power supplies that can pull current
through the entire AC full wave cycle (1 phase or 3 phase)?

A flyback (boost) converter run at a fixed duty cycle draws current
that is just about proportional to applied voltage, so it can produce
a very high power factor if the single phase line is filtered with a
low value of capacitance. The effect is not as good for 3 phase
sources, but three stages (one per phase) can do as well. If the
converter is run in current mode, and the current setpoint is
modulated with a factor proportional to the absolute line voltage the
effect is even better. Gaining a high power factor this way
necessitates ripple voltage on the output of the converter. I have
seen designs that subsequently buck regulate the output a second time
to eliminate the ripple.

--
John Popelish