Re: Magnetic Rectifier??

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "davep by way of Terry Fritz <twftesla-at-qwest-dot-net>" <davep-at-quik-dot-com>

Tesla list wrote:
> 
> Original poster: "Antonio Carlos M. de Queiroz by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <acmq-at-compuland-dot-com.br>
> 
> Tesla list wrote:
> >
> > Original poster: "Ed Phillips by way of Terry Fritz <twftesla-at-qwest-dot-net>"
> <evp-at-pacbell-dot-net>
> 
> >         Are you saying that a reactor, with the core saturated in one
> direction
> > by a DC magnetizing force or a permanent magnet will have a steady-state
> > DC component in the current which can flow through it when an AC voltage
> > is impressed?  Gotta think that through some more, but don't see how
> > that could happen.  Don't have a simulation program which includes a
> > model for saturation, and am trying to figure out an EASY experiment.
> > Gave plenty of magamp cores of all sizes, so might be able to rig it.
> > More discussion please.
> 
> The idea is to insert an inductor in the AC path, that has an extra
> winding where a DC current is applied (a magnetized core would work too,
> but a DC current adds easy control). A transformer with AC in one coil
> and DC in the other. The inductor would normally
> present a high impedance to the AC circuit, with little current flowing
> through it. When the sum of the magnetic fields produced by the DC
> and AC currents causes the inductor core to saturate, the inductance
> falls to a low value, and the AC current flows more intensely.
> Since the bias is DC, the "inductive switch" will operate at just one
> side of the AC cycle. The resulting current will look as a small AC
> waveform (sinusoid) with high current pulses at the centers of the
> swings of one polarity. The width of the pulses can be controlled by
> the DC current. These devices are very robust, although not very
> efficient. I have seen they used in (rather old) high-power battery
> chargers, with a diode connecting the AC+pulses current to the
> batteries.

	The ones i saw (worked on (fixed....)) Had a diode to do the
	rectification WITH AN AC (only) magamp for the control, ie:
	before the power rectifier.

	(this dates back to the days before solid state power
	devices.  Controlling large currents at low voltages was
	tricky... )

	While i guess a magamp-like could be used as a rectifier of sorts,
	it would (as noted) be a lot less desirable than many other
	approaches.

	best
	dwp